An-Najah National University Faculty of Graduate Studies Grid and Environmental Impact Assessment of 0.5 MWp Photovoltaic Power System Connected to Salfit Governorate Electricity Distribution Network By Osama Bani Nemrah Supervisors Dr. Tamer Khatib Prof. Amer EL-Hamouz This Thesis is Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Clean Energy and Conservation, Faculty of Graduate Studies, An-Najah National University, Nablus – Palestine. 2021 ii iii Dedication To my father and mother To my brother and sister To my wife Sondos To my grandfather and grand mother iv Acknowledgment I would like to thank my thesis supervisors; Dr Tamer Khatib and Prof. Dr. Amer EL-Hamouz, many thanks are also given to Clean Energy and Conservation Master program members at An-Najah National University, many thanks and appreciations also go to all the people who helped me conduct this study. v vi List of Contents No. Content Pages Dedication iii Acknowledgment iv Declaration v List of Tables ix List of Figures xi List of Acronyms and Abbreviations xiv Abstract xvi Chapter One: Introduction 1 1.1 Background 1 1.2 Problem Statement 5 1.3 Research Objectives 6 1.4 Research Methodology 7 1.5 Significance of the Work 9 1.6 Thesis Organization 10 Chapter Two: Literature Review 13 2.1 Introduction 13 2.2 Grid-Connected PV systems 15 2.2.1 Penetration Level and the Possible Impacts 18 2.3 Electricity Distribution Network 20 2.4 Power Flow Analysis 25 2.5 EIA Historical Background 29 2.6 Environmental Policies and Regulations in Palestine 31 2.6.1 Palestine environment law 31 2.6.2 Palestine EIA Procedure 33 2.7 World Bank EIA Procedures 35 2.8 Solar Radiation Data Collection for Palestine 39 Chapter Three: Modeling of Salfit Electricity Distribution Network 42 3.1 Introduction 42 3.2 Salfit Electrical Network 43 3.3 Modeling of the Electrical Grid 46 3.3.1 Generator 46 3.3.2 Transformer 48 vii 3.3.3 Transmission Line 51 3.3.4 PV systems 53 3.3.5 One-line Diagram 58 3.3.6 Load Flow Analysis 58 3.4 Electrical Grid Analysis and Consumptions 61 Chapter Four: Impact of PV Distributed Generation on Grid 65 4.1 Introduction 65 4.2 Design of the Proposed Photovoltaic System 66 4.2.1 Solar radiation 67 4.2.2 Location of the Proposed System 68 4.3 Grid Impact and Consequences for PVD 69 4.3.1 Voltage regulation 70 4.3.2 Real and Reactive power 71 4.3.3 Power losses 71 4.3.4 Power Factor 72 4.3.5 Power system stability 72 Chapter Five: Environmental Impact Assessment of The Proposed PV System 77 5.1 Introduction 77 5.2 Project Description 80 5.2.1 General Description 80 5.2.2 Expected Yield Energy and Technology 80 5.2.3 Project Work Intervals 81 5.3 Screening and Scoping and Terms of Reference Drafting of the Project 82 5.3.1 Screening 82 5.3.2 Environmental and Social Risk Assessment 89 5.3.3 Scoping and Terms of Reference: 93 Chapter Six: Environmental and Social Study 107 6.1 Introduction 107 6.2 Legislation Framework 107 6.3 Gap Analysis between Palestinian Laws and World Bank Safeguard Statements 108 6.4 Public Participation and Site Visits and Stakeholder‟s Engagement 117 6.5 Grievance Mechanism 119 viii 6.6 Environmental and Social Management Plan 121 6.7 Monitoring Plan 132 Chapter Seven: Prefeasibility of the Proposed System 138 7.1 Introduction 138 7.2 System Cost 139 7.3 Energy Yield 140 Chapter Eight : Result and analysis 142 8.1 Grid impact analysis 142 8.1.1 Voltage regulation 145 8.1.2 Power Factor and Bus Loading 149 8.1.3 Branch Loading and Branch Losses 153 8.1.4 Short Circuit Analysis 158 8.2 System Feasibility 162 Chapter Nine: Conclusions and Future Work 164 9.1 Conclusion 164 9.2 Future Work 165 References 166 ب الملخص ix List of Tables No. Title Pages 2.1 Comparison between the three types of the networks 24 3.1 Salfit city general information 42 3.2 Yearly consumption of Salfit city since 2016 62 3.3 Etap general results for the electrical network without PV systems 63 3.4 Monthly consumption for Salfit city for the past 4 years 63 3.5 Etap software general results for the electrical network with PV systems 64 4.1 The avrage monthly energy output for 0.5 MWp 67 5.1 Expected yield energy for 25 years from 0.5 MWp 81 5.2 Properties of the proposed project 86 5.3 List of the potentially affected elements 87 5.4 The possible impacts and the mitigation measures 88 5.5 Risk assessment criteria 90 5.6 Risk assessment for each element 91 5.7 Environmental elements simple matrix table 97 6.1 Stakeholders engagement procedures 118 6.2 Environment and social management plan 122 6.3 EIA monitoring plan 133 7.1 Bill of Quntity 139 7.2 Environmental assessment estimated cost 140 7.3 Estimated energy produced for 25 years lifetime from0.5 MWp 141 8.1 Cases classifications 142 8.2 Voltage, power factor, loading for bus 64,49 and bus 78 145 8.3 Voltage level for bus 46,49 and 78 in each case compared to the original 146 8.4 Bus 46,49 and bus 78 power factor level compared to the original case 150 8.5 Bus 46,49 and bus 78 loading levels compared to the original case 150 8.6 Total consumption and power factor 153 8.7 Real power and reactive power losses 154 x 8.8 Short circuit current 159 8.9 Revers power on bus 23 and bus 40 161 8.10 Voltage drop in lines 161 8.11 System viability using RETscreen software 163 xi List of Figures No. Title Pages 1.1 Schematic diagram of a grid-connected PV system 2 1.2 Flow chart of the EIA process 4 2.1 Typical component of domestic grid connected photovoltaic system 16 2.2 Typical PV plant connected to the grid 17 2.3 IEEE 69 bus system 21 2.4 Ring distribution network 22 2.5 Mesh network architecture 23 2.6 Flow chart for Palestine EIA procedure 35 2.7 Average hourly profile for 0.5 MWp PV system 40 2.8 Monthly average output power for 0.5 MWp 40 2.9 Annual yield factor for PV system on Palestine from 1 kWp 41 3.1 Salfit master plan map 43 3.2 Customers types and percentage in Salfit city 44 3.3 Phasor diagram for the generator 47 3.4 Equivalent circuit for the generator 48 3.5 Ideal transformer equivalent circuit 49 3.6 Practical transformer equivalent circuit 51 3.7. Equivalent circuit of medium length transmission line 51 3.8 Equivalent circuit of long transmission line 52 3.9 Equivalent circuit of short transmission line 52 3.10 Single diode model for solar cell 54 3.11 I-V curve of a pv module and the effect of Rs and Rp 56 3.12 The maximum power point (MPP) corresponds to the biggest rectangle that can fit beneath the I –V curve 56 3.13 Relation between temperature and power out put 57 3.14 Relation between solar radiation and power output 57 3.15 Part of One-line diagram for Salfit electrical network 58 3.16 Etap one-line diagram of the network with PV systems 64 4.1 Scheme diagram for PV station 66 4.2 Solar energy for one year of 0.5 MWp 67 4.3 PV layout for 0.5 MWp system 68 xii 4.4 PV station connection to the grid 69 4.5 Medium voltage with and without PV 70 4.6 Classification of power system stability based on the dynamics of the phenomenon 73 5.1 GIS picture for Salfit city 84 5.2 GIS picture for the project area 85 5.3 Leopoled matrix 98 8.1 One-line diagram for part of the electrical network 143 8.2 Power factor level for each bus before connecting the station. 144 8.3 Real power losses in each branch before connecting the station. 144 8.4 Reactive power losses in each branch before connecting the station 145 8.5 Voltage level for bus 46 ,49 and bus 78 compared to the original 146 8.6 Case1 voltage level compared to the original case. 147 8.7 Case 2 voltage level compared to the original case. 147 8.8 Case 3 voltage level compared to the original case. 148 8.9 Case 4 voltage level compared to the original case. 148 8.10 Power factor level for case 1 compared to the original. 151 8.11 Power factor level for case 2 compared to the original. 151 8.12 Power factor level for case 3 compared to the original. 152 8.13 Power factor level for case 4 compared to the original. 152 8.14 Bus loading in MW for all cases compared to the original case. 153 8.15 Real and reactive power losses for all cases compared to the original 154 8.16 The branch loading in each case compared to the original case. 155 8.17 Case 1 reverse power in near buss to the connection point to the grid. 156 8.18 Case 2 reverse power in near buss to the connection point to the grid. 156 8.19 Case 3 reverse power in near buss to the connection point to the grid. 157 8.20 Case 4 reverse power in near buss to the connection point to the grid. 157 8.21 Case 2 thermal figure for bus loading 158 xiii 8.22 Thermal representation for the short circuit analysis 160 8.23 Cash flow for installing 0.5 MWp 163 xiv List of Acronyms and Abbreviation PVDG Photovoltaic-based distributed generations PV Photovoltaic THDv voltage total harmonic distortion DG distributed generations EIA Environment impact assessment DFIG Doubly Fed Induction Generator CHP Combined Heat and Power CSP Concentrated solar power GCPVS Grid connected PV systems UFP Under frequency protection OFP Over frequency protection UVP Under voltage protection OVP Over voltage protection US United states OECD Organization for Economic Cooperation and Development EU European Union UNEP United Nations Environmental Program EQA Environmental Quality Authority PEL Palestine environment law OP Operation policies EA Environment assessment FI Financial Intermediaries ESS Environment and social standard PENRA Palestinian Energy and Natural Recourses GHI Global Horizontal Irradiation DNI Direct Normal Irradiation IEC Israel electricity company PERC the Palestinian Electricity Regularity Council MPP maximum power point kWh Kilo watt hour IEAR Initial environment assessment report TOR terms of references ESIAR Environment and Social impact assessment report xv GIS Geographic information system ESMP Environment social management plan WB World bank NPV Net present value IRR Investment rate of return PBP Pay bake period PF Power factor xvi Grid and Environmental Impact Assessment of 0.5 MWp Photovoltaic Power System Connected to Salfit Governorate Electricity Distribution Network By Osama Bani Nemrah Supervisors Dr. Tamer Khatib Prof. Amer EL-Hamouz Abstract The increasing demand for electrical energy associated with finding new distribution generation elaborate the choice to go toward renewable energy. With its low maintenance and operation, it is becoming more of a trend around the world. A type of renewable energy source and the photovoltaic systems installation connected to the grid are on the increase since the past decade. This increase is elaborated with changes in voltage profiles, power factor, short circuit currents, and loading in the buses and transmission lines affecting the power quality delivered to the customers. These technical changes must be considered in line with the environmental impact associated with the project area to the flora, funa, noise, waste, water, etc. Such factors must be studied to understand the impact of these projects on each element. This thesis studies the ability to establish 0.5 MW of PV connected to Salfit municipality to decide the maximum penetration level allowed to be installed. It also studies the environment and social impacts under the umbrella of the World Bank environmental and social standard- ESS compared to the original. The first case is that of full generation and full load; the second one is a full generation and half load; the third one is a half-generation and full load; and, the last one is a half-generation and half load. Half of the study considers the electrical part while the World Bank‟s xvii ESS standards are considered in studying the environmental impacts. This thesis shows changes in the voltage profiles up to 7 Volts certain line in medium voltage level and a drop in the power factor from 0.87 to 0.82 in best scenarios; with an increase in the losses associated with an increase in short circuit levels by using ETAP software for load flow analysis. Additionally, this thesis studies the feasibility of the system installed using RET screen software by establishing a net present value study and simple payback period. This, accordingly, shows that the project is financially feasible with a three-year payback period and positive net present value with a rate of return of 32.8 % and energy production cost of 44.13 $/MWh. This thesis depicts a temporally negative environmental impacts on the project area regarding the environmental elements, such as the polluted area from the dust, the noise increases during the work, implementation, transportation issues, water problems, and waste materials problems. It also establishes an environmental impact mitigation plan and monitoring plan to control and minimize the consequences associated with the system during the pre-construction stage, construction stage, and operation and maintenance stage, on the other hand the project shows a positive impact related to the employment, CO2 emission reduction by 2559.2 ton per year. 1 Chapter One Introduction 1.1 Background The growing power demand has increased electrical energy production almost to its capacity limit. However, power utilities must maintain reserve margins of existing power generation at an enough level. Currently, transmission systems are reaching their maximum capacity because of the huge amount of power to be transferred. Therefore, power utilities must invest a lot of money to expand their facilities to meet the growing power demand and to provide uninterrupted power supply to industrial and commercial customers. The introduction of photovoltaic-based distributed generations (PVDG) in the distribution system may lead to several benefits such as voltage support, improved power quality, loss reduction, deferment of new or upgraded transmission and distribution infrastructure, and improved utility system reliability. PVDG is a grid-connected generation power unit located near consumers regardless of its power capacity or type of unit. It is an alternative way to support power demand and overcome congested transmission lines. The integration of PVDG into a distribution system will have either positive or negative impacts depending on the distribution system operating features and the PVDG characteristics. PVDG can be valuable if it meets at least the basic requirements of the system operating perspective and feeder design. 2 Figure (1.1) below shows a schematic diagram of a grid-connected PV system which typically consists of a PV array, a DC link capacitor, an inverter with filter, a step-up transformer, and a power grid. The DC power generated from the PV array charges the DC link capacitor. The inverter converts the DC power into AC power, which has a sinusoidal voltage and frequency like the utility grid. The diode blocks the reverse current flow through the PV array. The transformer steps up the inverter voltage to the nominal value of the grid voltage and provides electrical isolation between the PV system and the grid. The harmonic filter eliminates the harmonic components other than the fundamental electrical frequency. PV Array DC Link Inverter Filter Transformer Grid Figure (1.1): Schematic diagram of the grid connected PV system. It is commonly known that PVDG needs to be installed at the distribution system level of the electric grid and located close to the load center. Studies are usually conducted to evaluate the impact of PVDG on power flow, power quality, and short-circuit analyses are very essential to assess the impact of PVDG on the grid before its installation (Khatib et. al., 2021). To reduce power losses, improve system voltage and minimize voltage total harmonic distortion (THDv), appropriate planning of power system with the presence of DG is required. Several considerations need to be considered, such as the number and the capacity of the PVDG units, the optimal PVDG location, and the type of network connection. The 3 installation of PVDG units at non-optimal locations and with non-optimal sizes may cause higher power loss, voltage fluctuation problems, system instability, and amplification of operational cost. In terms of the environmental impact of the project, an Environmental impact assessment (EIA) will be developed. It is a tool to minimize the negative impact of human activities on the environment. The purpose of the environmental impact assessment is to first assess the impact of a proposed activity on the environment before deciding on whether to go in more details in assuming its impacts. EIA can be defined as a process of collecting information about the environmental impacts of a proposed project and consequent relevant decision-making. EIAs also consider aspects and mitigation measures which should be applied if the project can minimize or avoid its Impacts. The process of EIA comprises several different stages such as screening, scoping, reviewing, and completion. These stages of EIA may be labeled differently in different parts of the world, but their goals are similar. In the EIA process, a range of organizations may be involved, including government agencies, developers, nongovernmental, and public organizations. The level of involvement may vary significantly depending on the type of project that is assessed. The World Bank strategy for implementation EIA will be taken since it‟s stricter than the Palestinian standards. Despite the variation of the EIA process in the world with respect to the funding agencies and decision makers, it‟s ended with an impact assessment report, which will inform the stake holders and the decision makers whether to approve or reject the project. Figure (1.2) 4 underneath shows a flow chart that illustrates the process of the EIA process. Figure (1.2): Flow chart of the EIA process. 5 1.2 Problem Statement 1. Technical impact of the proposed system. The integration of PVDG in power systems can alleviate overloading in transmission lines, provide peak shaving, and support the general grid requirement. However, improper coordination, location, and installation of PVDG may affect the power quality of power systems. Most conventional power systems are designed and operated such that generating stations are far from the load centers and use the transmission and distribution system as pathways. The normal operation of a typical power system does not include generation in the distribution network or the customer side of the system. However, the integration of PVDG in distribution systems changes the normal operation of power systems and poses several problems which include possible bi-directional power flow, voltage variation, breaker non- coordination, alteration in the short circuit levels, and islanding operation. Therefore, studies are required to address the technical challenges caused by DG integration in distribution systems. The interconnection device between the DG and the grid must be planned and coordinated before connecting any DG. 2. Environment impact of the proposed system It is important for decision-makers, funding agencies, and any stakeholder of any project to be fully aware of the environmental impact of the project. Firstly, it makes it easier to decide on this project. Thus, the second statement of the problem is described as the importance of assessing the 6 environmental and social impact of the system considering its impact on many aspects; such as land, air quality, water, and pollution impact on plants and animals. Thus, there is a need to conduct an environmental impact study considering all the procedures illustrated in Figure (1.2) above. This must be followed by consulting the stakeholders as well as the public in Salfit governorate to draft an environmental management plan which will be the environmental and social reference for the contractor when implementing the project. 1.3 Research Objectives In this thesis, five main objectives are aimed to be fulfilled as below: 1. To study the impact of a 0.5 MWp photovoltaic system on Salfit grid voltage profile and power flow. 2. To estimate the optimum penetration level of renewable energy and location to support Salfit distribution network. 3. To conduct an environmental impact assessment of the system. 4. To draft an environmental and social management plan for the project according to the World Bank procedure. 5. To conduct feasibility of the proposed system. 7 1.4 Research Methodology W.P 1 Data Collection T1.1 The load on the network and the network instruments T1.2 Define and locate the project area and start the screening process WP.2 Literature Review T2.1 Literature review on grid-connected PV systems and electricity distribution network T2.2 Literature review on power flow analysis and electricity distribution network loading and stability T2 .3 Literature review on the environmental impact assessment procedure. Of the World Bank and current environmental policies and regulations in Palestine. T2 .4 Data collection of solar radiation data for Palestine must be provided. WP.3 Modeling of Salfit Electricity Distribution Network T3.1 Construct a one-line diagram for the electrical network. T3 .2 Modeling the electricity network using Etab software T3 .3 Construct power flow analysis of the network 8 WP.4 Design of the Proposed Photovoltaic System and the Impact of a Proposed Photovoltaic System on the Electricity Distribution Grid T4.1 Studying the impact level after connecting the proposed system using: (a) 100% loading and 100% generation, (b)50% loading and 100% generation, (c) 50% loading and 50% generation, (d) 100% loading and 50 % generation T4 .2 Studying the Distribution grid power flow analysis, grid power factor, and Distribution grid transformers loading levels T4 .3 Estimating the maximum penetration level of renewable energy generation into the grid WP. 5 Environmental impact assessment of the proposed PV system. T5.1 Identifying and defining the project or activity T5 .2 Screening and scoping and terms of references drafting of the project WP. 6 Preparation of final environment and social study T 6.1 Public consultation and Administrative or Judicial Review T 6.2 Final EIA report and environmental and social management plan preparation T6 .3 Gap analysis between Palestinian Laws and World Bank Safeguard statements. 9 WP. 7 Conduct a prefeasibility of the proposed system T7.1 Estimating system costs including grid requirements as well as Estimating environmental management plan costs T7 .2 Estimating the saving, including power losses and penalties WP 8. Results analysis T8 .1 Results analysis and conclusion 1.5 Significance of the Work The grid impact studies of the PV systems connected to the grid are essential to understand the variation and the changes that occur in the network for future planning and expansion. This happens with the association of understanding the potential effect of the renewable energy systems on voltage levels, power losses, power quality, power factor, penalties, and the obstacles for delivering reliable power for the end-user. Not to mention that the environmental studies are essential to understand the effects and the changes that occurred on the proposed area for these projects. This takes place by defining the positive and negative impacts on the environment then identifying the mitigation measures to minimize the negative impacts to the lowest level as much as possible. 10 1.6 Thesis Organization The thesis consists of nine chapters, as follows: Chapter 1: Introduction Includes an introduction, background, problem statement objectives, methodology, and significance of work. Chapter 2: Literature Review Review of papers of literature using open literature materials, including scientific journals, papers and articles, published reports related to grid connected PV systems, power flow analysis, review of papers related to the environment impact assessment, the procedures of the world bank, the environmental regulation on Palestine, as well as sampling the data of the solar radiation on Slafit and the instrument of the electrical network. Chapter 3: Modeling of Salfit Electricity Distribution Network Conduct Salfit electricity distribution network by constructing the one-line diagram and running the load flow by ETAP software and modeling all the electrical components and define the consumption Salfit city. Chapter 4: Impact of PV Distributed Generation on Grid Design the proposed system by starting with the first phase of installing a 0.5 MWp PV system and study the impact level after connecting the proposed system using: (a) 100% loading and 100% generation, (b) 50% loading and 100% generation, (c) 50% loading and 50% generation, (d) 11 100% loading and 50 % generation study the impact with different scenarios of loading and generation, and study the power flow for the grid, then deciding the maximum penetration level. Chapter 5: Environmental Impact Assessment of the Proposed PV System This chapter introduce the process of the environmental impact assessment starting with defining the project and project area, then starts with the screening process. It then defines the terms of reference based on defining the positive and negative impact of the project through the project implementation phases. Chapter 6: Environmental and Social study Prepare an EIA study according to the World Bank requirements and environmental and social framework and conduct an environmental management plan and monitoring plane considering the World Bank frame work and define the legislation frame work and the grievance mechanism. Chapter 7: Prefeasibility of the Proposed System Prepare a feasibility study to estimate the implementation cost for all the electrical component and estimate the environmental procedure cost, then define the methods used to find if the project is feasible or not. 12 Chapter 8. Result and Analysis This chapter provides an analysis of the results obtained from conducting the electrical network under the four case and defines the impact on the power factor, voltage levels, power losses, short circuit currents and bus loading, then define the feasibility of the system. Chapter 9: Conclusion and Future Work This chapter represents the conclusion achieved by applying the four scenarios and introduces the future work recommendation for conducting PV station to grid. 13 Chapter Two Literature Review 2.1 Introduction The increasing demand for energy and electricity made the utilities reach almost their full capacity. However, the power utilities must have a reserve for future expansion. Therefore, power utilities must invest a lot of money to expand their facilities to meet the growing power demand, and to provide uninterrupted power supply to industrial and commercial customers (Peterson et. al., 1972). Power plants are typically located far from load centers, power losses and voltage drops are high. In this respect, installing distribution generation (DG) near load centers can contribute to solving these issues (Razavi et. al., 2019: 160). Different types of renewable and nonrenewable DG are available including wind turbines, thermal solar, solar photovoltaic (PV), hydro power, Desil generators, fuel cells, geothermal and micro turbines (Daly & Morrison, 2001). With many concerns related to climate change, and due to the increase in load demand and power losses, this encouraged the installation of the DG on the electrical networks. However, this increase in the installation has a significant impact on the electrical networks. DG is categorized according to the active and reactive power delivered to the distribution system into the following groups (Hung & Mithulananthan, 2010: 818): 14 1. DG with active power injection: only this type of DG is connected to the distribution system using an appropriate power electronic interface. This includes small-scale DG units which operate at a unity power factor, such as PV, fuel cells, micro turbines, and batteries. 2. DG with reactive power injection: only DG units of this type operate at a unity power factor, supplying the required reactive power of distribution systems. Synchronous compensators fall under this category. 3. DG with active power injection and reactive power absorption: this type of DG used in wind turbines. Different types of those induction generators with improved performance exist, such as fixed-speed, variable-speed, and Doubly Fed Induction Generator (DFIG). They inject active power into the grid while absorbing reactive power. 4. DG with active and reactive power injection: this type of DG is based on synchronous machines such as gas turbines and Combined Heat and Power (CHP) units, capable of injecting both active and reactive power into the grid. As one of the DG types; the solar photovoltaic (PV) became the most applicable choice for most of the countries around the world, regarding the amount of energy from the solar radiation the PV industry shows a decrease in the production prices for the PV systems. Growing of PV for electricity generation is one of the highest in the field for renewable 15 energies and this tendency is expected to continue in the coming years (IEA-PVPS T1-18:2009). 2.2 Grid-Connected PV Systems Solar power generation is divided into two types: photovoltaic power (PV) and concentrated solar power (CSP). The difference between the two types is that the CSP uses the heat of the sun to generate power while PV uses solar radiation. Additionally, the CSP with some certain technologies can store the heat while the PV systems can‟t do that on large scales. The PV system converts the solar radiation into DC then converts it to the AC connected to the grid. Grid-connected PV systems (GCPVS) are a type of DG connected to the electrical network working simultaneously with the utility distribution system with a certain percentage of penetration. The GCPVS is preferred over the conventional DG systems because of its low price, low operation cost, low maintenance cost, and it is considered environmentally clean. Parida et. al. (2011: 1627) reviewed solar photovoltaic technologies and concluded that the increased efficiency, lowering cost, and minimal pollution associated with it has led to its application in several energy projects, such as building-integrated systems, pumps, solar home systems, desalination plant, Photovoltaic, and thermal (PVT) collector technology. The energy created by the solar arrays powers the load directly with any excess being sent to the utility, resulting in net metering (WEC, 2020). Figure (2.1) below shows typical components of domestic grid-connected photovoltaic (PV) system, starting from the modules collecting the solar radiation, DC wiring, inverter, AC wiring, and 16 then the utility connection, while Figure (2.2) illustrates typical PV plant connected to the grid. Figure (2.1): Typical components of domestic grid-connected photovoltaic (PV) system (Jenkins, et. Al., 2018) 17 Figure (2.2): Typical PV plant connected to the grid (Hunter et. al., 2019: 244) Despite all parts of the GCPVS, the inverter is the most essential one since it is required to supply constant voltage and frequency, despite the load variation conditions and the need to supply or absorb reactive power in case of reactive load (Prakash et. al., 2016). The inverters are connected to the grid supplying electricity. Due to this interaction, the inverters are required to have protection technology like islanding protection. Islanding protection means that the inverter must be turned off when the electricity from the grid is interrupted. According to IEEE 1547 in section 4, PV system power must be de-energized from the grid within two seconds of the formation of the island; this means PV plants interconnection system shall detect the island and cease to energize the grid within two seconds of the formation of the island. Not to mention that the inverter must not connect within 60 seconds of the grid reestablishing power supply after power failure (Hoke et. al., 2016). Additionally, the inverters should have over-frequency protection and under frequency protection (UFP/OFP). The 18 inverters are required to have under-voltage protection and over-voltage protection (UVP/OVP). This means that the inverters must stop working and supplying power to the utility grid if the frequency or the amplitude of the voltage is beyond the prescribed limits. 2.2.1 Penetration Level and the Possible Impacts Generally, most common conventional power systems and DG are designed and operated such that the generation stations are far away from load centers, and they use the transmission and the distribution as pathways (Abdul Kadir et. al., 2014: 7). Due to the trend of using renewable energy as a backup generation source and the concentration on using PV systems, studies aim to find the potential impact whether it is electrical or environmental. Since the solar radiation is variable making the output power unpredictable, improper design and installation of the GCPVS may cause negative impacts on the grid. In any power system, the power that is generated from the station is transmitted through transmission lines to the loads (Khatib et. al., 2021), but with the improper coordination and installation of the GCPVS, the power may flow in both directions. For distribution areas, even a small amount of PV systems may impact the system parameters if the load and the generation are not closely matched (Hoke et. al., 2016). (Willis, 2004) and (NREL, 2011) states that if the renewable sources capacity penetration is 30 %, it is considered high and requires a smart grid integration to ensure reliable grid operation. The following points represent some of the common impacts associated with the PV system installation: 19 1. Reverse power flow: the excess energy generated from the high penetration of DG on the grid is called reverse power. The reverse power will flow through the transmission lines and the substations. Furthermore, reverse power flow at the substation transformer level may affect voltages and loading limits for some transformers (Cipcigan & Taylor, 2007: 160). 2. Voltage regulation: the penetration level of the PVDGS on the grid will affect the voltage profiles on the network especially the areas near the PV systems causing the voltage levels to rise, making the utility plans for expansion limited. On the other hand, complaints from customers will occur. Not to mention the loads which are far away from the plants will suffer from voltage variability. 3. Unbalanced voltage and current: if the penetration of the PV systems in one phase is higher than the others, this will make the voltage, or the current deference higher causing reverse power flow or overloaded for the transmission lines. 4. Feeder loading and Power losses: the appropriate installation and sizing for the PVDGS on the grid will reduce the line currents on the transmission lines. Additionally, the power losses will decrease. On the other hand, if the penetration level increases, the amount of the currents flowing in the line will also increase, causing overloading for the lines. Then, the power losses will increase, and a reverse power will occur as 20 well. This thing will happen on the transmission line several times during the day. 2.3 Electricity Distribution Network Appropriate installation and designing of the electrical network are the main reasons for a good service to the end-user. Power provision to individual customer‟s premises can be enhanced through an efficient and proper electrical power and distribution system. A typical distribution network consists of a substation of substations, primary feeders, transformers, distributers, and service main (Taher & Afsari, 2012). With the increasing demand and renewable energy trending in the world, appropriate design and technologies for the electrical networks are required. The most commonly used network architectures are radial network, ring network, and mesh network. The definition, advantages, and disadvantages are discussed below. 1. Radial network: the most commonly used type of electrical network in distribution systems, the architecture of the network can be represented with a tree with no closed loop in it. The topology of the network is made from the main connection bus then transmission lines to the other buss. Figure (2.3) below illustrates the architecture of the radial network. This type of electrical network is characterized by its simplicity of installation and expansion and it‟s also easy to determine the system requirements for protection and cable sizing. This type of electrical network is preferred when the station is located at the center 21 of the loads as it brings simplicity to analyze and operate the system. However, with this type of electrical network, interruption or faults happens that risk the system shutdown. Not to mention the system flexibility for more load addition is low since it may require a replacement for all the electrical components. Figure (2.3): IEEE 69 bus system 2. A ring network: the architecture of the network can be represented with a closed-loop starting from one source feeding the loads from different routes. In other words, all the nodes in the ring network are connected in such a way that they make a close loop structure making runs through or around an area, serving one or more distribution transformers or load center, and returns to the same substation (Reprint Edn et. al., 2006). In this type of network, the power can be transferred in more than one way making the system more reliable with a good performance. Thus, any interruption that occurs does not affect the system. On the other hand, it is more complex to detect the location of the fault. Additionally, the lines connected to the load should be able to cover all the demand in any 22 case. In terms of complexity, a loop feeder system is only slightly more complicated than a radial system and has a major drawback of catering to the capacity and cost of the loop system (WEC, 2020). The below Figure (2.4) illustrates the architecture of the ring network. Figure (2.4): Ring distribution network (Parida et. al., 2011: 1627) 3. Mesh network: A mesh network structure follows the radial structure but includes redundant lines in addition to the main lines. These are organized as backups to reroute power in the event of failures to the main line (Electrical Grid, 2020). Figure (2.5) shows the structure of the mesh network. The mesh network is more complicated and more complex from the radial and the ring network due to the connectivity options with the load, making the control configuration more difficult. It is still more reliable than the other networks. The advantages of the meshed network are the relatively balanced voltage profile and high reliability through redundancy (Ahmad & Dakyo, 2013). Table (2.1) 23 below shows a comparison between the three types of networks (Prakash et. al., 2016). Figure (2.5): Mesh network architecture (Parida et. al., 2011: 1627) 24 Table (2.1): Comparison between the three types of the networks Network Source Stability reliability Capital cost maintenance Voltage level protection Penetration Radial Single Low Low Low High Low Medium Problematic Ring Multiple High Medium High Low Low High Accepted Mesh Multiple High High Low High Medium Higher Moderate 25 2.4 Power Flow Analysis The continuous increase in the demand associated with different types of loads and penetration levels of the DG on the utility grids requires an expansion of the power system. This expansion requires a comprehensive study of the power system. Overall, the result courses from this expansion. For the past years, a lot of methods were written and implemented to solve the power system problems associated with voltage profile variability under transient and steady-state stability occurring from the load expansion with different types and requirements, since the loads themselves are categorized under residential, commercial, and industrial. Load flow is the procedure used for obtaining the steady-state voltage for an electric power system at fundamental frequency (Herraiz et. al. ,2003). The voltage stability for a power system is to have a constant voltage for all the busses on the network. The load flow study for the power system gives us the voltage levels on each bus, real and reactive power, phase angle, power factor, transmission lines loading, transformer loading, and the results which occur from the expected future expansion. Various types of methods were obtained to solve a nonlinear equation like the Gauss Seidel method, Newton Raphson, and Fast Decoupled but still, all these methods suffer from drawbacks. Peterson et. al. (1972) presented a fast-approximated method for solving the AC power flow problem for line and generator outages, which is applicable for system future planning and fast installation criteria. 26 There is a suggested method for the analysis of load flow in radially operated 3-phase distribution networks. This method does not fix the famous conventional load flow equations. Such a method applies to distribution systems with unbalanced loads. It is important to note that the size of the used matrix is noticeably small in comparison with the conventional methods. The used memory is little, whereas the speed is considerably high. Subsequently, the relative speed of calculation increases per the system‟s size (Golkar, 2007: 334). There is an algorithm for a fast continuation load flow to determine the critical load for a bus. This is by its voltage collapse limit of the inter- connected multi-bus power system. It uses the criterion of the singularity of load flow of the Jacobian Matrix. This method has been tested on IEEE 30 and IEEE 118 bus systems for validity. (Chakavorty & Gupta, 2012: 18) To solve unbalanced radial distribution systems, there has been a suggested simple and efficient algorithm. This algorithm has the property of a good convergence for any practical distribution network with a practical R\X ratio. Such a method is perceived to be very efficient (Cipcigan & Taylor, 2007: 160). There has also been a suggested methodology to solve the radial flow of analyzing the optimal capacitor sizing problem. Every network branch in this method is written in terms of the branch power flow and bus voltage. Subsequently, there has been a decrease in the number of equations by using terminal conditions connected to the main feeder and its laterals. The 27 Newton-Raphson method is applied to this reduced set. Not to mention that the computational efficiency is thus improved by simplifications made to the Jacobian method (Baran & Wu, 1989). Three various algorithms have been also suggested to solve radial distribution networks per the proposed method of Baran and Wu by Chiang (Chiang, 1991: 135). They had proposed decoupled, fast decoupled, and very fast decoupled distribution load-flow algorithms. The first two which were proposed by (Chiang, 1991:135), were akin to Baran and Wu‟s (Baran & Wu, 1989). there has also been a proposed direct method for solving radial and meshed distribution networks by Goswami and Basu (Goswami & Basu, 1991: 80) Their method, however, has the limitation of having no node in the network which functions as the junction of more than three branches; i.e. one incoming and two outgoing branches. Additionally, to fix radial distribution networks, (Das et. al., 1994: 292) also propose a load-flow technique that calculates the wholly real and reactive power which are fed through any node. This method functions by applying the power convergence with the assistance of the coding at the lateral and sub-lateral nodes of large systems; all of which heightens the complexity of the computation. However, such a method was only applicable to sequential branch and node numbering schemes. Forward sweep has been used to calculate the voltage of each receiving end node. They first attempted to solve radial distribution networks using zero initial power loss. It turned out that it can solve simple algebraic recursive 28 expressions of voltage magnitude. As such, all the data is easily stored in vector form. Hence, a huge amount of computer memory is saved. Another efficient method to solve both radial and meshed networks by using more than one feeding node has been suggested by Haque (Haque, 1996). Haque‟s method first converts the multiple-source mesh network into an equivalent single-source network. This is conducted by adding dummy nodes. This could be subsequently followed by the traditional ladder network method which applies to radial systems. Different from the previously introduced methods, this method incorporates the effect of shunt and load admittances; since it could be applied to solve special transmission networks. It is important to note that this method has an excellent convergence for the radial network. To fix the power flow problem in radial distribution systems, Eminoglu and Hocaoglu (Eminoglu & Hocaoglu, 2005) suggested a simple method that is based on the voltage dependency of static loads as well as line charging capacities. This method is built on the forward and backward voltage updating by making use of the polynomial voltage equation and backward ladder equation for every branch. The suggested algorithm has a solid convergence capacity in comparison with the improved module of the classical forward-backward ladder method. For a load-flow solution of radial distribution networks, Ghosh and Sherpa (Chosh & Sherpa, 2008: 2097) proposed a method with less data preparation. This method applies the simple equation to calculate the 29 voltage magnitude. This method also can manage composite load modeling. However, for this algorithm to be implemented, huge programming efforts must be made. Gurpreet Kauur (Kauur, 2012), on the other hand, suggests a new algorithm to solve the radial distribution networks by applying a method of load-flow and a sequential numbering scheme. His method, which aspires to decrease the data preparation, suggests a way to identify the nodes beyond each branch with minimal computational effort. 2.5 EIA Historical Background at the beginning, it was introduced in the United States (US) then it was followed by several countries and institutions. It was considered a severe procedure for the implementation of some projects. The first country that developed an EIA system was the US. The social awareness for the environmental impacts and the mitigation procedures reached a high proportion by the med of 1960. With this increase, the National Environmental Policy Act (1969), and for the first time, EIA requiring environmental consideration in large-scale projects were enforced as legislation. Following the US initiative, many countries started to provide EIA systems like Australia (1974), France (1976), Pakistan (1983), and many other countries. 30 From the cooperation of several international countries like the Organization for Economic Cooperation and Development (OECD) and the European Union (EU), the EIA took its first steps around the world in the 1980s. In 1982, United Nations Environmental Program (UNEP) began with the adoption of the world laws of nature. The law stated that EIA should be implemented to ensure the minimization of the impact of any suggested project on the environment. Then, UNEP 1987 established a committee for EIA discussion and implementation and established standards and regulatory models. On the other hand, the organization for economic cooperation and development (OECD) declared the environmental policy in 1974 which was to protect the environment. Article 9 stated the following to prevent future environmental deterioration, prior assessment of the environmental consequences of significant public and private activities should be an essential element of policies applied at the national, regional and local levels (OECD). In 1985, the European Union (EU) instruction towards the EIA was adopted. These instructions require a defined EIA to be implemented before the approvals for any project with potential environmental impact, so all the countries in the EU should perform an EIA by the end of 1988 (European Commission, 2021). World Bank (WB), a multi-faced institution that gives loans and finance to the developed countries and their developed projects, adopted the 31 environmental policy in 1984. In 1989, it stated the operational directive related to EIA, and in 1998, the final draft of the operational policies was completed (International Finance Cooperation, 1998). 2.6 Environmental Policies and Regulations in Palestine 2.6.1 Palestine environment law In Palestine, Enviroment Quality Authority (EQA) regulates and sets policies for the environmental sector. EQA was established in 1996 with the ambition to maintain and protect the environment in Palestine. It has two headquarters, one is in the city of Ramallah and one in Gaza. It also has offices distributed in major cities. Measures have been taken by the Palestinian Environmental Legal and Administrative Framework for the protection of environmental resources and organizing their management. PEL, an abbreviation for the Palestinian Environmental Law, comprehensively covers major issues of the environment, its protection, and the enforcement of the law. Some of its goals are as follows: 1. Trying to reduce pollution to protect the environment. 2. Maintaining social and public health. 3. Placing protection of environmental resources in future social and economic plans. 32 4. Focusing on the protection of significant ecological areas and the rehabilitation of ruined areas. 5. Placing regulations and various protective standards in many environmental areas. 6. Promoting environmental awareness through training. Additionally, PEL highlights diverse issues of the environment, such as: 1. It highlights the issues of land, air, water, and other natural and historical resources. 2. It conducts an Environmental Impact Assessment for environmental projects. 3. It sets penalties and punishments to whoever violates the law or its items. The legislation also addresses issues of environmental emergencies and the incorporation of the public in environmental research and training. In 1999, PEL has declared that “Ministry, in coordination with the competent agencies, shall set standards to determine which projects and fields shall be subject to the environmental impact assessment studies. It shall also prepare lists of these projects and set the rules and procedures of the environmental impact assessment”. 33 2.6.2 Palestine EIA Procedure Under the umbrella of the Palestinian National Authority, the Environmental Quality Authority (EQA) is the legislative institution for the environment acting laws, which is responsible for environmental quality and applying the environmental law and the EIA procedures written in the Palestinian law. The implementation of the EIA procedure aims to provide a sustainable economic and social in Palestine by achieving the following (EQA, 1997): 1. Setting a standard for an appropriate life that does not marginalize the basic needs of the people as well as their social values through any developmental activity. 2. Maintaining the capability of the environment to self-sustainment. 3. Protecting the biodiversity of the landscapes. 4. Minimizing and avoiding environmental damage from environmental projects. The Palestinian EIA procedure starts with applying for environmental approval containing a description for the proposed project with a screening for the proposed area. The screening criteria and output determine whether the project needs an EIA and determine whether the project is likely to (EQA, 1999): 34 1. Diversely use of a natural resource to promote other uses of the same resource. 2. Cause the displacement of people. 3. Take place near areas of high sensitivity, i.e. reserves, historical site, etc. 4. Cause high environmental impacts. 5. Be a source of public concern. 6. Need more developmental activities which subsequently will lead to further impacts on the environment. Then it must be provided with an initial environmental evaluation and then an environmental impact assessment report if the project contains significant effects on the environment. Figure (2.6) illustrate the EIA procedure according to the PEL. 35 Figure (2.6): Flow chart for Palestine EIA procedure (EQA, 1999) 2.7 World Bank EIA Procedures International finance corporation OP/BP 4.01 operational policies, 1998, an Environmental Assessment (EA) of environmental projects is required by the World Bank to follow certain criteria based on certain data. Such EA is supposed to provide a clear spectrum of the environmental outputs and impacts of any environmental project. EA, thus, is supposed to provide an assessment of potential risks, other proposed alternatives, the siting, the implementation strategy, the positive impacts, and ways to improve the project (International Finance Cooperation, 1998). 36 Therefore, EA must keep into consideration the natural resources of air, water, soil, and plants. Not to mention the safety aspects of human life, the physical cultural resources, and the life of the indigenous people. (International Finance Cooperation, 1998). Accordingly, the Bank assigns the Borrower country to be responsible for carrying out the EA. It is part of the Borrower‟s responsibility to retain highly professional experts to conduct the EA. Sometimes, if a project is risky or of high significance, then the Borrower may also employ an advisory panel of environmental specialists (International Finance Cooperation, 1998). Henceforth, the Bank advises the borrower based on the outputs retained by the EA on what further recommendations or/and measures to be undertaken (International Finance Cooperation, 1998). For the Bank to determine the highlights of EA, then an environmental screening of any environmental project must be conducted. A project is thus classified into one of the following categories (based on type, siting, the significance of the project, impacts, etc.) (International Finance Cooperation, 1998): 1. Category (A): This includes the projects of high environmental sensitivity and impacts. 2. Category (B): This includes projects whose environmental risks and impacts are of less significance than the Category (A) projects. 37 3. Category (C): This refers to projects of minimal environmental impacts. 4. Category FI: This refers to the projects that are funded by the bank through an intermediary. In the case of FI, the Bank requires to have a screen of the subprojects and appropriate EA. The Bank, additionally, investigates the compatibility of a country‟s environmental requirements with a certain project. (International Finance Cooperation, 1998). The Bank also suggests certain policies for projects of urgent need of assistance based on the institutional capacity, public consultation, disclosure, and implementation. For institutional capacity, the Bank requires that the project includes components that strengthen the borrower‟s capacity should it have a certain inadequate capacity. A consultation is also required to be conducted by the borrower by which it consults other affiliated groups and NGOs. Their perspectives on the project and its environmental impacts must be taken into consideration. Before the consultation, the borrower must disclose an appropriate and intelligible summary of the project, its aspects, and its prospected impacts. As for the implementation, the Bank requires a report from the borrower about the project, how it meets the measures stipulated by the Bank, and the mitigation measures (International Finance Cooperation, 1998). A Category (A) environmental assessment report should highlight the environmental issues of the project. Accordingly, it should include the following stipulated aspects: an executive summary that includes the 38 findings and recommendations, a description of the project based on geographical, ecological, and social levels, a baseline data which assesses the scope of the project and its dimensions, a prediction of the prospected environmental impacts, an assessment of the alternatives, an environmental management plan which looks into mitigation measures and monitoring, and a list of appendices. The new world bank environmental and social framework replaced all the Policy (OP) and Bank Procedures (BP), OP/BP4.00, Piloting the Use of Borrower Systems to address Environmental and Social Safeguard Issues in Bank Supported Projects, OP/BP4.01, Environmental Assessment, OP/BP4.04, Natural Habitats; OP4.09, Pest Management; OP/BP4.10, Indigenous Peoples; OP/BP4.11, Physical Cultural Resources; OP/BP4.12, Involuntary Resettlement; OP/BP4.36, Forests; and OP/BP4.37, Safety of Dams. This Framework does not replace OP/BP4.03, Performance Standards for Private Sector Activities; OP/BP7.50, Projects on International Waterways; and OP/BP7.60, Projects in Disputed (The World Bank, 2017). Also, the new world bank frame work classifies the project upon the risk associated with the project implementation: 1. High risk. 2. Substantial risk. 3. Moderate risk. 4. Low risk. 39 2.8 Solar Radiation Data Collection for Palestine The rate of deployment of solar PV systems is greatly influenced by the perception of the general public and utilities, national policies, as well as the availability of suitable standards and codes to govern it. According to the major drop in PV systems cost, the PV systems have become a very feasible source of energy with the addition of the decrease in its component, installation, and maintenance also with the availability of the source (the Sun). The geographical area and the climate for Palestine keep the generation level of the PV system at its maximum efficiency. Palestine is in the geographical region between the Mediterranean Sea and the Jordan River. At latitudes of 31 and 33 degrees and longitudes of 34 and 36 degrees. Its elevation ranges from 350 m below sea level in the Jordan Valley, to sea level along Gaza Strip shore, and exceeding 1,000 m above sea level in the hilly areas of the West Bank. According to the Atlas of Solar Resources for Palestine issued by PENRA in 2014, Palestine has high solar radiation potential; on an annual average, the Global Horizontal Irradiation (GHI) is higher than 1900 kWh/m 2 and the Direct Normal Irradiation (DNI) is higher than 2000 kWh/m 2 and the average solar radiation of 5.4 kWh/m 2 /day. According to the Atlas, the average energy production from a 1 kW PV system is between 1700 and 1775 kWh/kWp and it will reach 1800 kWh/kWp in Gaza (Atlas of Solar, 2014). The below Figure (2.7) illustrates the average hourly profile for 0.5 MWp system and, Figure (2.8) shows the monthly average output power for 0.5 MWp system. 40 Figure (2.7): Average hourly profile for 0.5 MWp system (Global Solar Atlas, 2008 Figure (2.8): Monthly average output power for 0.5 MWp (Global Solar Atlas, 2008) 41 Figure (2.9): Annual yield factor for PV system in Palestine from 1 kWp (Atlas of Solar, 2014) 42 Chapter Three Modeling of Salfit Electricity Distribution Network 3.1 Introduction Salfit governorate is in the northwest of Palestine resting on a group of mountains 520m above sea level. Salfit city has a population of 11602 people according to the Palestinian Bureau of Central Statics, with a total area of 23117 Dunm for the governorate. Despite the surrounding settlements, Salfit consists of an area of 5694 Dunm. Table (3.1) below represents general information for Salfit city and, Figure (3.1) represents Salfit master plan. Salfit area is divided into four main categories, residential area with 3527 Dunm, industrial area with 715.8 Dunm, commercial area with 230 Dunm, agricultural area with 77.7 Dunm, and 1374.3 Dunm located in area C and some of them are located outside the master plan. Table (3.1): Salfit city general information General Information Description Governorate Salfit City Salfit Population 11602 Coordination 32°06'11", 35°07'09 43 Figure (3.1): Salfit master plan (Shtayeh, 2021) 3.2 Salfit Electrical Network Salfit purchases electricity from Israel Electrical Company (IEC). While Salfit municipality manages the distribution of electricity between the city of Salfit and three other villages (Farkha, Skaka, Amorya), the electrical department at the municipality, which contains two electrical engineers and 44 four electricians, is responsible for the maintenance and the operation of the electrical network. Salfit electrical network is connected to the Israeli side from a one connection point with a total capacity of 120 Amp at a medium voltage rated at 33 kV. With a total medium voltage network of 21000 m and 120 km low voltage, Salfit‟s electrical network provides electricity for 5252 customers who are divided into four main categories: residential with a total number of 4289, industrial with a total of 192, governmental 117 and commercial with a total number of 654 and street lighting of 19. Beneath, Figure (3.2) shows the percentage for each type. Figure (3.2): Customers types and percentage in Salfit city Slafit Municipality approved connecting the photovoltaic systems on the grid in 2017 by taking into consideration the framework determined by the Palestinian Electricity Regularity Council (PERC) following the net metering for the connection. Since 2017 and until February 2020, the total number of customers is 66 with a total capacity of 601 kW in Salfit only. 81.60% 3.25% 12.56% 2.23% 0.36% 0.00% 20.00% 40.00% 60.00% 80.00% 100.00% 1 P er ce n ta g e custumer type Custumer percentage Residential Industrial Comercial Govermental Street lighting 45 However, in Farkha village, the total number of customers is 27 with a total capacity of 127 kW. Additionally, Farkha is connected to a PV station with a total capacity of 270 kW that is connected to the medium-voltage lines. Skaka and Amorya, on the other hand, still underway to get approvals from their council to permit the installation of the PV systems. The transmission lines in the electrical grid are mostly of overhead aluminum ACSR with a total number of transformers of 36 that convert the voltage from 33 KV to 0.4 KV in Salfit and the three other villages with 1,273 Km of underground cable. Additionally, the network has an ABC aluminum cable with a total length of 130km distribution network that consists of the following components:  ACSR overhead cables  Medium voltage Underground cable  38 transformers represented as [630 kVA (14 units), 400 kVA (12 units), 250 kVA (7units), 150 kVA (1 unit), 160 kVA (2 units)]  PV project systems  ABC aluminum cable  (6x25) mm  (4x50 +2x25) mm 46  (4x95+2x50) mm  Wooden poles  Steel poles  Steel M.V. towers  Steel ladders 3.3 Modeling of the electrical grid To understand the behavior of the electrical network and its elements, we need to understand its equivalent circuit and mathematical description. In other words, it‟s called the molding of power system elements. These models will give us a good description of how these elements work in all conditions starting from the generator, to the transmission line, to the transformer, and ending with the loads. 3.3.1 Generator A generator is an electrical machine that converts mechanical energy into electrical energy. The type of generator that we are interested in is the synchronous generator. The synchronous generator is made from two main parts; a stationary part which is called a stator and a rotating part called a rotor. The rotor rotates inside the stator producing what is called field winding; which is supplied by DC that produces magnetic force from its rotation. This force produces a flux between the air gap between the stator and the rotor and makes the current go throw the slots attached into the 47 stator. The speed of rotation of the generator depends on the number of the pole that‟s made off (Stevenson, 1975: 565) according to the following equation: (3.1) Where f is the frequency in hertz, P is the number of poles, N is number of rotations. To represent the equivalent circuit for the generator, Figure (3.3) represent a phasor diagram for the flux and the electromagnetic force were the: Øf : the rotor flux Ea0 : no load voltage which equals Ef Øf : total flux from Øf+ Øar and that gives us Ør Ear : the result of the armature current= Figure (3.3): Phasor diagram for the generator (Stevenson, 1975: 565) 48 From the phasor diagram (3.2) Due the armature leakage reactance ( ) and armature current the output voltage, Figure (3.4) represents the equivalent circuit for the generator. (3.3) , – (3.4) Figure (3.4): Equivalent circuit for the generator (Stevenson, 1975: 565) 3.3.2 Transformer A transformer is an electrical device that converts voltages from high voltage to lower voltage or vice versa. For us to understand the circuit model and mathematical formulas for our practical transformer, we will take the ideal transformer as a simple approach. The most important aspects of the ideal transformer are that the permeability of the core is finite and the resistance of the transformer is zero (Stevenson, 1975: 565). The following Figure (3.5) represents the ideal transformer equivalent circuit: 49 Figure (3.5): Ideal transformer equivalent circuit From Figure (3.5) “the voltage induced in each winding by the charging flux is also the terminal voltage since the winding resistance is zero” (Stevenson, 1975: 565). By applying Faraday law: (3.5) (3.6) Where: d ø : for constant flux. N : number of turns. And, if we assumed that the applied flux is sinusoidal: (3.7) To find the relation between the two winding currents, we apply Amperes law which relates the current to the field intensity around a closed bath: (3.8) 50 Where (i) is the current enclosed by the line integral and H represents the field intensity, and, for the currents in two windings, we obtain: (3.9) and, as we know, the integration over a closed-loop equals zero: (3.10) (3.11) Where: N: number of turns. i: the current in the primary and the secondary sides of the transformer As for the practical transformer, which has a few differences from the ideal like permeability, it is not finite. Winding resistance is present, and it has iron core losses. Not to mention that the practical transformer has two types of losses: first, eddy current losses due to the current induced in the iron = I 2 *R. Second, the hysteresis current and is dissipated as heat. Figure (3.6) shows the equivalent circuit of the practical transformer after neglecting the magnetization current since it is too small compared to the load current (Stevenson, 1975: 565). 51 Figure (3.6): Practical transformer equivalent circuit 3.3.3 Transmission line Whether it‟s a head or an underground cable, the main purpose of the transmission line is the connection between the elements of the power system starting from the generator and ending with the load. The transmission lines are classified into three main categories: first, less than 80 km is short; second, between 80 km to 240 km long; third, over 240 km needs an additional calculation (Stevenson, 1975: 565). Figures (3.7, 3.8, 3.9) represent the equivalent circuit for all types of transmission line (Manuel Reta-Hernavndez, 2006). Figure (3.7): Equivalent circuit of medium length transmission line 52 Figure (3.8): Equivalent circuit of long transmission line Figure (3.9): Equivalent circuit of short transmission line The resistance of the transmission line can be expressed by the following equation (Stevenson, 1975: 565): (3.12) Where : the resistivity of the material L : the length A : the cross-sectional area 53 While the inductance of the transmission line depends on the distance between the line and the length of the line, it can be expressed by the following equation: (3.13) Where GMR is the geometric mean radius and equals to (e -1/4 r =0.778 r) and the GMD represents the distance between three conductors, and it is expressed by this formula: √ (3.14) Where D1, D2 and D3 represents the distance between the three conductors. And as for the short model of the transmission line that we are mainly interested in, the following equation represents the resistance and the reactance of the model: (3.15) (3.16) Where rd is the series resistance and is the series reactance. 3.3.4 PV systems The PV (photovoltaic) systems mainly consist of a PV module that absorbs sunlight to produce electricity (dc), then connect it to the inverter to convert the dc power into ac power and then connect it to the grid. The PV system took its place in the electrical power system since the number of the systems and its rated power is increasing significantly. This increase made 54 the PV studies for the grid impact essential. Modeling the PV systems is used for power flow calculation, short circuit calculation, voltage stability studies, and harmonic interaction studies. The PV systems circuit can be modeled using a single diode model which is illustrated in Figure (3.10) (Cuk et al, 2011). Using the single diode model as it‟s shown in the following Figure, the current and the voltage characteristic can be represented by the following equation (Cuk et al, 2011): Figure (3.10): Single diode model for solar cell (Masters, 2004). (3.17) Where Vocstc is the open circuit voltage in STC and is the open-circuit voltage temperature coefficient (V/°K). ( ) (3.18) Where G is irradiation and GSTC is irradiation in STC(1000W/m2), Isc,stc is the short circuit current at STC, Tref is the reference temperature at STC (298°K) and is the short-circuit current temperature coefficient. The photovoltaic cell is combined with other cells to perform a group of 55 modules that represents a PV array. The output current of the PV array can be represented as follows: (3.19) And the output voltage of the cell: (3.20) Then, from the output voltage and current, we can find the power produced from the module Where: Vd : voltage junction Rs : series resistance Rp : parallel resistance The output power of the module depends on the parallel resistance and the series resistance to improve the output power the Rp should be high and Rs should be zero. Figure (3.11) below represents the I-V curve of the PV module and the effect of the parallel resistance and series: 56 Figure (3.11): I-V curve of a PV module and the effect of Rs and Rp (Masters, 2004). The inverter in the PV system works to produce the highest power of the PV. This is represented with the largest rectangle that can be drawn under the I-V curve. Also, to draw this rectangle, we need the MPP (maximum power point) to represent the highest voltage and the highest current. This can be done with a device called the tracker. Figure (3.12) shows the amount of the output power with different points in the IV curve: Figure (3.12): The maximum power point (MPP) corresponds to the biggest rectangle that can fit beneath the I –V curve (Masters, 2004). 57 Since the current produced is a function of temperature and radiation, the following figure shows their effect on the output power. The increasing temperature will reduce the output power as it‟s illustrated in Figure (3.13) the ambient tempreture higly influence the performance of PVS ((Aziz et. al., 2019). However, the increase in the radiation will increase the output power as it‟s illustrated Figure (3.14): Figure (3.13): Relation between temperature and power output (AlNozahy & Salama, 2013) Figure (3.14): Relation between solar radiation and power output (AlNozahy et.al, 2013:032702) 58 3.3.5 One-line diagram The One-line Diagram is a combination of all power system elements used in the grid which gives us consistent information about the electrical grid. The elements in the one-line Diagram are represented by simple symbols and not with their equivalent circuit. The amount of the elements represented in the diagram depends on the amount of information needed which is mainly used for the load flow analysis. The below Figure (3.15) represents the one-line diagram for Salfit electrical network. Figure (3.15): Part of the one-line diagram for Salfit electrical network. 3.3.6 Load flow analysis To study the performance of the electrical grid and its component, it is essential to do the power flow analysis; in other words, load flow analysis. The load flow analysis gives us a full indication of how the electrical grid works, which is also necessary for future planning for expansion and 59 control. It is additionally needed to understand the effects that might happen in the grid for the utility. The principle information obtained from load flow is the magnitude and the phase angle of the voltage at each bus and the real and reactive load flowing in each line (Ghiasi, 2018: 157). The following equation represents the formulation for the load flow starting with the following equation: (3.21) Where Ybus represents the matrix of the admittance of the power system. The nodal formula can be expressed as: ∑ (3.22) And the complex power can be expressed as: (3.23) Where P is the real power and Q is the reactive power on each bus, referring to I, ∑ ∑ (3.24) And according to Karim et. al. (2013), the complex injection power can be represented as: – (3.25) 60 Where is the complex generation power and is the load complex power, and the current injection can be represented as: (3.26) ∑ (3.27) ∑ (3.28) Where Gkj and Bkj as the real and imaginary parts of the admittance matrix element Ykj, respectively, so that Ykj=Gkj+jBkj, where is the admittance matrix then we can find the real and reactive power: ∑ (3.29) ∑ (3.30) Where: is the phase angle, P is real power, Q is reactive power, and |Vi| is voltage magnitude. The bus is the connection point between the transformer and the transmission line or the load. It is classified into three main categories: slack bus, generator bus, and load bus. In the past, the load flow analysis used to be done mathematically by three main methods; which are:  Newton Raphson Method: This method solves the following equation using the Jacobean matrix ( ) ( ) ( ) (3.31) 61 Where (J1to J4) represent the Jacobean matrix.  Fast-Decoupled Method: This method is derived from the newton Raphson method. It uses less iteration since its main principle is: any small change in the voltage will not affect the magnitude of the real power nor the complex power. The following equation represents the method: (3.32) (3.33)  Accelerated Gauss-Seidel method: This method uses the nodal voltage method to solve the following formula iteratively and it‟s the simplest iterative way to solve the power flow | | (3.34) Where in the equation P and Q are the specified bus real and reactive power , V is the bus voltage vector; Ybus is the system admittance matrix. and are the conjugates of Ybus and V, respectively; is defined as the transpose of V. 3.4 Electrical Grid Analysis and Consumptions As an engineer working in Salfit Municipality, I was able to access all the data needed for the analysis of the electrical network. To be able to fulfill this study, the analysis of the performance of the network started by 62 drawing the grid using AutoCAD software and the EATP software to fully understand the performance of the network, its applicability by adding the PV systems, and its impact on the grid. By referring to the financial department in the municipality, the average annual consumption of electricity for Salfit and the three other villages during 2016 to 2019 is 20008050 kWh (842739.7 NIS); with an annual increase in the demand of 1.2% as is depicted in the following Table (3.2): Table (3.2): Yearly consumption of Salfit city since 2016 Year Total bill (kWh) NIS 2016 18845000 7937514 2017 18721000 7885285 2018 19693000 8294692 2019 22773200 9592072 By returning to the monthly bills from IEC, the highest consumption of electricity is in summer. Hence, the stakeholders in Salfit Municipality decided to add and give permission for the installation of PV systems. Figure (3.16) below shows the one-line diagram of the grid without the PV systems per the customers from 2017 until the beginning of 2020. As we mentioned earlier, the total number of customers in Salfit is only 66 customers and 40 applications are pending for their confirmation to start installing their projects. 63 Table (3.3): ETAP software general results for the electrical network without PV systems Source MW MVAr MVA P.F Source (swing) 3.897 1.629 4.224 92.27 Source (non-swing) 0 0 0 0 Apparent loses 0.063 0.053 Table (3.4): Monthly consumption for Salfit city for the past 4 years Month 2016 2017 2018 2019 1 1600000 1900000 1850000 2220000 2 1500000 1550000 1520000 1830000 3 1450000 1500000 1350000 1650000 4 1400000 1200000 1250000 1778000 5 2020000 1290000 1575000 1530000 6 1000000 1576000 1590000 1752000 7 1740000 1970000 1950000 2340000 8 1800000 1850000 1880000 2250000 9 1500000 1575000 1778000 1980000 10 1600000 1430000 1500000 1753200 11 1620000 1230000 1450000 1650000 12 1615000 1650000 2000000 2040000 sum 18845000 18721000 19693000 22773200 From the above table, there is a slight increase in electrical consumption from the year 2017 to 2018. However, it increases in 2019 because of climate change which increases demand. Figure (3.16) shows the ETAP software analysis for the electrical grid with the PV systems. 64 Figure (3.16): ETAP one-line diagram of the network with PV systems. and after running the load flow analysis for the network, we get the following results: Table (3.5): ETAP software general results for the electrical network with PV systems Source MW MVAr MVA P.F Source (swing) 2.970 1.647 3.396 0.8745 Source (non swing) 0.917 0 .917 1 Apparent loses 0.045 -0.037 As depicted above, the power factor percentage is lower than the one specified from IEC which is 92%. By returning to the financial department, in 2019, there is a difference between the purchasing value and selling value of kWh due to the losses, which might be electrical losses or mechanical losses. 65 Chapter Four Impact of PV Distributed Generation on Grid 4.1 Introduction Distribution generation refers to any element in the power grid that produces electricity starting from the generators, wind turbine, PV stations, and municipal waste. The increasing energy demand made the utilities search for solutions to cover their peak demands. The distribution generation can be defined as small-scale, dispersed, decentralized, and on-site electric energy systems (Begovic, 2001). PV distribution generation (PVDS) was chosen to be implemented in Palestine since it is the only allowable generation source and because of the good irradiation in this country. With a variety of capacities ranging from kilowatts to megawatts, the installation of power plants is still going. The PVDG can be classified into four main categories: micro-scale, small-scale, medium-scale, and utility-scale. The PVDG integration in the electrical network may lead to severe consequences and might interfere with the system's capability to maintain the operation and the control of the system. The impact severity is a function of the penetration level (Begovic et. al., 2012).The impact of PVDG varies because of the instability of the out power of the PV plants since it depends on the weather (solar radiation and temperature). Therefore, the variety of the out power of the PV is quite wide due to shading issues and clouds. With the low capacity of the PV 66 systems, the impact of the PVDG is low. However, with a higher penetration level, the impact increases. 4.2 Design of the Proposed Photovoltaic System The commonly used PV model for each PV system consists of multiple steps, including finding solar irradiance in the sky projecting solar irradiance to the panel, determining the dc output from the panel, and converting the power output computable to the grid (Enslin, 2011). The inverter is used to convert the dc into ac and using the step-up transformer to make the voltage computable with the voltage grid as shown in figure (4.1) Figure (4.1): Scheme diagram for PV station Salfit municipality, which represents the electrical company for providing the electricity and maintenance for the electrical grid, is responsible for the network and any future planning. Nowadays, the municipality is following the trend by installing the PVDG on the electrical network aiming to achieve 5MW of PV connected starting from 0.5 MW as the first phase of the project. 4.2.1 Solar Radiation 67 Salfit is one of Palestine‟s governorates that is characterized by the solar radiation to which it is exposed during the year. Figure (4.2) and table (4.1) show average monthly output power for the 0.5 MWp station Figure (4.2): Solar energy for one year of 0.5 MWp (Global Solar Atlas, 2008). Table (4.1): The avrage monthly energy output for 0.5 MWp Month Output energy yield from 1kWp Output energy yield from 0.5 MWp Month kWh/kWp kWh Jan 110.5 55250.3 Feb 112.3 56146.9 Mar 148.1 74046.4 Apr 155.9 77957.8 May 174 86990 Jun 176.1 88032.6 Jul 181.7 90848.3 Aug 179.7 89848.1 Sep 164.7 82339.1 Oct 145.5 72771 Nov 120.7 60328 Dec 111.3 55668.3 Yearly 1780.5 890226.7 68 From figure (4.2) , it‟s clear that the output power of the station varies with the amount of solar radiation during the month with its highest values between May and September. 4.2.2 Location of the Proposed System With an optimum tilt angle of 28 degrees facing the south as it is illustrated in the figure (4.3) with 130 m away from the nearest connection point, while the longitude and the latitude for the proposed location is (35.18131, 32.07461) (Global Solar Atlas, 2008), while the physical location is between Salfit city and Amorya village and it‟s going to be connected to the bus (46) as it is shown in figure (4.4). Figure (4.3): PV layout for 0.5 MWp system 69 Figure (4.4): PV station connection to the grid 4.3 Grid Impact and Consequences for Grid Connected PV Systems The DG of conventional sources has a predicted impact on the grid since its output and input are controllable. However, the intermittent DG (e.g., photovoltaics, wind) poses specific challenges given the volatile and uncontrollable nature of its primary source (Begovic et. al., 2012). Regarding the increase in the percentage of power systems connected to the network, the impact of these DG may lead to severe consequences related to the voltage regulation, power factor, and power losses real and reactive power, reverse power flow; which may affect the system stability. 70 4.3.1 Voltage Regulation It can be defined as the difference between the actual voltage and the line voltage. The distribution networks are traditionally designed based on the downstream flow of power from the transmission network to the distribution network(Kharrazi et. al., 2020). Voltage regulation caused by the high penetration of the PVDG. The PVDG is connected to the electrical network since the output power of the PV depends on the climate. The out power which varies during the day causes the voltage change on the bus to which it is connected. However, the effects are particularly pronounced when a large amount of solar PV is installed near the less loaded feeders (Kumar & Selvan, 2017). This means that if the PVDG is at high levels, this will cause the voltage feeder to rise and may cause a reverse power. Figure (4.5) beneath shows the impact on voltage with and without PVDG with nominal load and light load: Figure (4.5): Medium voltage with and without PV (Demirok et. al., 2009). 71 4.3.2 Real and Reactive power The most important aspect of the PVGD for utilities is that it reduces the peak demand and lowers the cost for the infrastructure. The PVDG provides the utility with real power injected into the network which causes the reduction of the demand and reduces the losses of the real power if the station is near the center of loads. However, the reactive power losses will increase as the real power is reduced from the connection point while the reactive power is kept the same. Reactive power is not less important than real power since reactive power makes it possible to transfer real power through transmission and distribution lines to customers (Borges & Falcao, 2006: 415). 4.3.3 Power losses Reducing power losses is one of the advantages related to the PVDG. With low penetration of PVDG, the total current consumed by the feeder will reduce and cause a reduction in the power needed to be connected to the bus or through the lines. However, the large penetration level of PVDG may cause a reverse power flow and increase the magnitude of the line distribution current, line losses, and equipment loading (Begovic et. al., 2012). 72 4.3.4 Power Factor As we know, the power factor can be represented as a function of the real power and reactive power represented by the following equation: (4.2) Where: Q: reactive power. P: real power. Increasing the real power injected into the network will reduce the amount of power consumed from the connection point. As a result, the power factor will reduce and thus cause penalties to the utilities. This impact can be reduced by making the inverter of the PV not working in unity power factor. But, by allowing them to produce reactive power to compensate for the reduction in the power factor. 4.3.5 Power system stability An IEEE/CIGRE Joint Task Force on Stability Terms and Definitions has defined the power system stability as the ability of an electric power system for a given initial operating condition to regain a state of operating equilibrium after being subjected to a physical disturbance with most system variables bounded so that practically the entire system remains intact (Kundur, 1994). However, since the power system is considered with the wide variability of the components and the faults and the condition that 73 might occur on the power system or its components, a simple approach is considered to describe the system's stability. The following graph illustrates a summary for the classification of power system stability based on the dynamism of the phenomenon. Figure (4.6): Classification of power system stability based on the dynamics of the phenomenon (Kundur, 1994). For more understanding of the power system stability study and analysis, the fault can be represented with switching (on and off). Then, the behavior of the system depends on the type of fault that occurred whether it‟s a small or large fault. Afterward, a few points need to be checked to see if the system is stable or not, as well as the router angle, voltage stability, and frequency stability. 74 Rotor angle: its ability of the synchronous machine is to stay in synchronism after a fault or disturbance happens. Staying in synchronism means that the electromagnetic torque stays in synchronous rhythm with the output mechanical power of the prime mover. This rhythm might be broken with a large disturbance or a small one, such as; a low load disconnection of turning off a generator or it might be a large load. For more understanding of the rotor angle and the behavior of the synchronous machine, the swing equation will represent that as follows: 𝛿 (4.3) Where: 𝛿: angle between rotor field and reference angle (angular position of the rotor at any instant. : Angular displacement. Ws : synchronous speed. Differentiate both sides of the equation two times: (4.4) (4.5) 75 The result represents the angular acceleration 𝛼= elec.rad/s 2 (4.6) The accelerating torque in a synchronous generator equals the difference between the mechanical input shaft and the electromagnetic output torque (4.7) Where: Ta: accelerating torque Ts: shaft torque Te: electromagnetic torque While the angular momentum of the rotor is expressed by the following equation: (4.8) Where: M: angular momentum J: moment of inertia w: synchronous speed of the rotor 76 And we know that: (4.9) Can be expressed as the following: (4.10) Where: Pa: accelerating power input Ps: mechanical power output Pe : electrical power But, (4.11) (4.12) (4.13) (4.14) Equation (4.14) gives the relation between the accelerating power and the angular acceleration. 77 Chapter Five Environmental Impact Assessment of the Proposed PV System 5.1 Introduction In Palestine, Environment Quality Authority (EQA) represents the main institution for enacting laws of the environment, and it works to ensure sustainability in Palestine. The EQA aims to improve the environment quality, maintains its diversity, and encourages economic and social improvements in ways that do not affect the environment (EQA, 1999). According to EQA, the following projects are listed as the ones which need a full environmental impact assessment:  Power generation plants  Quarries and mines  Water treatment plants  Cement factories  Solid waste dumps  Facilities that store dangerous materials  Airport and runways  Ports and harbors 78  Oil refineries  Industrial cities  Reservoirs and dams  Main roads  Iron and steel Since our project is considered as part of the power generation plants, there is a need to have a “no objection” for the project from EQA. Hence, the following steps represent the executive procedures for the environmental assessment for any proposed project:  Environmental approval request (ERA).  Initial environment assessment report (IEAR)  Environment and social impact assessment report if needed.  Environmental approval request (EAR): The (EAR) is a document prepared by the proponent related to the project to ask related authorities, i.e., EQA, the Municipality, Palestinian Energy and Natural Recourses Authority (PENRA), etc., for no environmental objection. The EAR should contain a description of the project and a list of its activities and impacts on the environment. In our case, the municipality is the responsible authority to be contacted first. 79  Initial environment assessment report (IEAR): If the project is found to have a non-severe environmental impact, then EQA will ask the proponent to prepare an (IEAR). The IEAR includes a full description of the project with its environmental impacts. Hence, the EQA officer will make a site visit to the project site