Electrical Power Engineering

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https://hdl.handle.net/20.500.11888/13968

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Smart Grid as a Potential Solution for Problems of Local Electric Network in Tulkarem City/ Palestine
(An-Najah National University, 2017-08-23) الجلاد, محمد يوسف مسعود; بعباع, معتصم
In the twenty-first century, the most critical and important issues relating to energy systems are smart grid technologies and renewable energy technologies. The development of the current centralized generation in the form of distributed generation and smart grids offers a great opportunity to eliminate many issues related to energy efficiency, energy security, energy quality and the defect of the outdated energy system infrastructure. The current electrical systems in Palestine are decades old and dependent upon equipment that is approaching the end of its usable life. Smart grid gives an opportunity to update power network infrastructure, ensuring that safety standards continue to be met, that power is delivered consistently, and that the system is managed efficiently. For the specific case of Tulkarem city, the power network suffers of major problems. These problems include peak load violation, high technical and non-technical losses, lack of control over loads and the new evolving distributed generation. Peak demand puts considerable stress on the grid, increasing the risk of blackouts in very hot or cold days. It also significantly raises the year-round price of power for consumers. Better information and decision-making during times of peak demand could significantly reduce generation costs and the risk of power outages. In this thesis, the researcher studied the possible strategies for converting the existing grid in Tulkarem to a smart grid. Some demonstrated technologies will have a part pretty in pushing ahead. This incorporates advanced digital meters (Smart meter), low-cost communication systems, distribution automation, and distributed energy resources. At the end, the researcher investigated the possibility to solve the chronic problems of existing power grid. Through data analysis and simulation, the researcher proves that it is possible to reduce peak loads and flatten the daily load curve by using an integral approach that includes smart metering, load control, distributed generation of PV systems and reasonable energy storage. This approach only possible with a smart grid with a suitable data communication network.
Improvement of Electrical Grid – Quality Parameters by LC-Filters, at Supplying of Power Electronics Converters
(An-Najah National University, 2018-03-22)
Recently, Power electronic devices are applied in many fields, mainly in the industry and domestic appliances. The major problem that faces the power system by these devices is the generation of current harmonics. These harmonic currents act as a source of pollution to the power system as they have the major following impacts: • Reduction of power quality parameter represented in power factor and system efficiency. • Increment of total harmonic distortion. This work investigates the mitigation of harmonic currents by different LC-filter configurations to improve the quality parameters of supplying electrical grid. Also it discusses the design and simulation of these LC passive filters within SCR rectifier. The performance parameters of the controlled rectifiers, with various LC-filter configurations, for RL–load and firing angles, investigated in this work are: input current THD, input power factor, efficiency and output voltage. This investigation was implemented by FFT analysis tool through MATLAB/SIMULINK. The simulation of a single phase full wave controlled rectifier with RL-load and a firing angle of α=30° has resulted in: THD=18.04%, PF=0.804 and rectification efficiency of η =73.53%. Inserting a series resonance LC-filter at the input of this rectifier, the simulation resulted in THD=2.52%, PF=0.745 and η=63.05% the corresponding reactive power to be installed in the LC-filter amounts to Q=39.053 kVAr. Investigating the insertion of a high pass T-LC filter, the simulation results in THD=4.27%, PF=0.842, η =77.87% and Q=14.96 kVAr. The results for the T-LC filter indicate a considerable improvement of the grid quality parameters (especially for THD) in comparison with the corresponding parameters of the rectifier without LC-filter. In addition, five LC-filter with different topologies were inserted at the input of the rectifier and investigated in the thesis. The simulation results of all seven filters show a significant reduction in the harmonic currents represented in THD for the different filters in the range of THD = 2.522%-5.15 %. Moreover, the rectification efficiency could be improved by a simple second order high pass LC-filter to achieve η =79.66% at an installed reactive power of Q=10.086 kVAr. The thesis compass investigating the mentioned main grid quality parameters beside other parameters for different firing angles of the above mentioned full wave controlled rectifier.
Optimal Sizing and Placement of Distributed Generation Using an Improved Particle Swarm Optimization (IPSO) Method for Power Loss Reduction and Voltage Stability Improvement
(ِAn-Najah National University, 2018-03-23) Hantash, Neda
The integration of distributed generation (DG) units in power distribution networks has become very important field in recent years. The aim of the optimal DG planning is to provide the best locations and sizes of DGs to optimize electrical distribution network operation taking into account DG capacity constraints. In this thesis an improved particle swarm optimization method (IPSO) is proposed to optimally choose suitable DG unit in accordance to DG size and location so as to improve voltage profile and reduce active power losses. IEEE 34 distribution bus system is used as a case study for this research. A new equation of weight inertia is proposed so as to improve the performance of conventional PSO algorithm. This development is done by controlling the inertia weight which affects the updating velocity of particles in the algorithm. Maltab codes are developed for electric power system, improved PSO algorithm and power flow analysis so as to conduct the research. Results show that the applied conventional PSO algorithm successfully finds the optimal size and location of the desired DG unit with a capacity of 1.6722 MW at bus number 10. This makes the voltage magnitude equals to 1.0055 pu and improves the status of the power system in general. The minimum value of fitness losses using the applied algorithm is 0.0406 while average elapse time is 78.6212 s. In addition to that, the applied PSO algorithm reduces the active power losses by 31.61%. As a comparison, conventional PSO algorithm that is based on linear inertia weight equations consumes 78.6212 s and 69.0836 s to provide the optimum solution. In the meanwhile, the proposed algorithm consumes 62.2325 s to provide the optimum solution
Analysis of Power Conversion Stages and Efficiency Improvement Possibilities for Grid Connected Pv System.
(Eman Omar Mahmoud Abu Hani, 2018-04-10) Abu Hani, Eman
In this thesis the improvement of large scale PV system conversion efficiency is presented. Mainly the inverter efficiency is considered to be improved by testing two different configurations of 100 kWp PV. The first configuration consists of one single centralized inverter and the second one of master-slave inverter. A Mathematical model is developed by MATLAB software to model the inverter efficiency as a function of input power then the power output is calculated by using hourly solar radiation and ambient temperature data over one year in Palestine. The simulation results show that the annual average energy production using the single centralized inverter is 181.26 MWh/year, while the annual production of master-slave inverter is 184.5MWh/year. In addition, by considering only the inverter efficiency the annual efficiency of DC/AC conversion stage for first system is 96.7% and for the second system is 98.4%. Economic analysis shows that the additional investment in master-Slave configuration instead of using single centralized inverter can be covered within six and a half years.
Design of A Fault-Tolerant Active Power Filter With Active and Reactive Power Injection Capability Using Multi-Level Inverter and Photovoltaic Array
(An-Najah National University, 2018-05-13)
The increasing use of nonlinear loads leads to increase the harmonic pollution in the main power system. Harmonics cause many power quality problems such as voltage distortions at Point of Common Coupling (PCC), changing peak-value and RMS-value of line current which will cause addition losses, overloading and overheating, failure of some electrical equipments as transformers, capacitors, and motors, circuit breakers will trip frequently, and damage fuses. Moreover, harmonics may cause interfering with telecommunication lines; therefore, the power quality will be affected. This thesis suggests a solution for this power quality problem through designing multitask active power filter which have the ability to mitigate harmonics, inject reactive power, improve power factor, inject real power and tolerate open circuit fault. The filter was designed and tested using MATLAB software and the results show improving in power quality. The Total Harmonic Distortion (THD) decreased from 13.9% to 3.9% after activating the APF and the power factor becomes nearly 1.0. The APF was tested during open circuit fault (one leg disconnected) and the result was acceptable because the THD decreased from 42% to 8.4% which mean that the filter has the ability to work under fault condition with minimum possible distortion.
Design of Active Power Filter with Active and Reactive Power Injection Capability, Using Multilevel Inverter and Photovoltaic Arrays
(An-Najah National University, 2018-05-20) حنتولي, نائل نجيب; صالح, كامل
The Hybrid Active Power filter (HAPF) consists of shunt active power filter connected with series active power filter at a common linking point. Itworked perfectly with total benefits of shunt APF and series APF. In other words, it can mitigate both the current and voltage harmonics. Subsequently, the HAPF can mitigate nearly all kinds of power purity troubles seen by distribution network. The shunt active power filter is controlled based on the “generalized theory of the instantaneous reactive power in three-phase circuits (p-q theory)", to compensate the load harmonics. The series active power filter is controlled based on the dual instantaneous reactive power theory to compensate the load harmonics. (HAPF) used 27-level asymmetrical inverters. Each phase of these inverters is composed of three ‘H’ bridges, supplied by three independent photovoltaic arrays Scaled in the power of three, delivering 12.5 kVA to each phase, 10kVA for shunt active filter and 2.5 kVA for series active filter, using multilevelinverters with more than 20 levels can deliver current waveforms with negligibletotal harmonic distortion. So they can implemented in active filter application without the need of filters. The outputs of inverters connected directly through a transmission line. In addition to the capability of harmonic elimination of both current and voltage drawn from the source, the combined system can produce real and reactive power to feed the loads during prolonged voltage outagesor source shortage. A battery pack used as dc link, which is charged from photovoltaic array connected to the battery through a maximum power point tracker and charge controller.The injection of real and reactive power depends on the state of charge (SOC) of batteries, the system frequency, type of the load, and power factor at the common linking point. The proposed Unified (HAPF) strategy is simulated in MATLAB SIMULINK and the results are shown.From simulation results, the system can mitigate all voltage and current harmonics and reduce the total harmonic distortion from 22% to 1%. In the other hand, it support the electrical network by injecting real power when it’s needed and maintain the stability of the electrical network. By using voltage reference generation control we will overcome the voltage matching problems, reduce the total harmonic distortion (THD) to minimum and eliminate the need of transformers.
Power System Harmonics Analysis Using Frequency-Domain Impedance Model of Network and Methods of Disposal
(An-Najah National University, 2018-05-23) مرداوي, علاء; خماش, ماهر
Power grids can be described as low power quality if they contain distorted currents which are known as harmonics. Harmonics mean that the alternating current (AC) wave contains multiple integers of the fundamental frequency. In the past, this distortion was caused by the elements of the network itself, such as transformers, when they enter the saturation area in periods of high demand for energy. The generators themselves produce waves with a slight degree of distortion because the distribution of the magnetic flux is not optimal. But nowadays, the main reason for the problem is the spread of nonlinear loads, especially power electronic devices, for domestic and commercial use. Several small devices spread through the whole network are participating in the distortion. Distortion due to harmonics has become very important in the field of power quality studies because of the negative effects of the distortion on equipment and what is accompanied by negative effects such as resonance. In order to understand the problem of harmonics, an accurate analysis of the network must be carried out in the presence of the sources of harmonics. The main goal of this analysis is to find different values of the distortion and to compare them with the standards set to the normal level. Also, such studies enable us to study the effectiveness of different procedures followed in eliminating harmonics and controlling their flow. In this thesis, a frequency-domain model of a distribution network was developed and an analysis was carried out to enable us to calculate the required values of distortion. All this was accompanied by a software simulation of the same network in order to compare the accuracy of the results. Problem statement The spread of nonlinear loads in the electric power systems will result in distortions in the current wave and thus distortion on the voltage, which is called the harmonics. These distorted currents will be injected back into the power supply to cause a negative effect on the power quality that is to increase the losses and reduce the power factor. The network equipment itself will also be subject to damage and downtime due to harmonics. This has necessitated worldwide interest in harmonics studies, including harmonics estimation, elimination and a variety of related areas. Objectives To learn how to form a frequency-dependent model for network elements depending on the nature of each element and how it behaves with harmonics frequencies. To develop a methodology for harmonics analysis of networks so that this method can be adopted by network operators as a guide to execute of various calculations related to harmonics. To study procedures used in harmonics mitigation and to ensure their effectiveness by simulation. To present all issues associated with harmonics such as general characteristics, sources, effects, harmonics indices and standards. Methodology A mathematical model for the whole electric network is developed in order to carry out harmonics power flow analysis by hand calculation. Later, the analysis is carried out to evaluate the developing method proposed by using a computer program ETAP12.6. Thesis layout The thesis is organized as follows: Chapter 1 provides a basic theory about harmonics and related topics such as distortion measurements, harmonics sequences and calculation of electrical quantities of distorted waves. Chapter 2 deals with the undesirable effects of harmonics as they pass through the various network equipment. It also looks at the effects on the entire network such as resonance. Chapter 3 covers the sources of harmonics in the electric network with a description of the nature of the harmonics injected during the operation of the device. Chapter 4 covers a brief discussion on standards for distortion limits. Chapter 5 models the network elements based on the nature of the interaction of the element with the passage of harmonics in it. Each element will be dealt with separately to get a frequency dependent impedance. Chapter 6 represents building a complete harmonics model for a distribution network and conduct an accurate analysis of harmonics frequencies, thus calculate the bus voltages and then calculate the distortion measurements. This is accompanied by simulations of the same network to determine the accuracy of the model and manual analysis. Chapter 7 covers several procedures that can be used for the mitigation of harmonics. A simulation was done to make sure that they are correct. Chapter 8 includes appropriate conclusions and suggestions for future work. Appendix A: includes MATLAB coding for harmonics voltages calculation. Appendix B: includes proof of phase shift (∆ to ∆/Y connection) method which is used for harmonics cancelation. Appendix C: includes filter harmonics currents calculation. Appendix D: includes selected examples of harmonics analyzer.
Techno-Economic Assessment of the Electric Grid –Connected PV Power Plant at Arab American University / Jenin
(Ahlam Hasan Abu Zahew, 2018-06-10) Abu Zahew, Ahlam
The performance of 70 kWp grid-connected PV system in Arab American University have been analyzed. The performance Parameters considered under this study are the final PV system yield, performance ratio and capacity factor. The economical assessment was also analyzed including cash flow, payback period, net present value and the unit energy cost. The annual system outputs were 100 MWh and 95 MWh in 2015 and 2016 respectively. May 2015 and 2016 had the highest output energy with approximately 12 MWh in both years. The PV final yield varies between 180 kWh/kWp in May and 47 kWh/kWp in January, with annual final yield of 1428 kWh/kWp and 1367 kWh/kWp for 2015 and 2016 respectively. With respect to performance ratio(PR) the system had an annual PR of 80% in 2015 and 76.8% in 2016. The monthly PR varied between 52% in Jan and 99% in March in 2015 and (34% in Sep and 99% in Nov) in 2016. On the other hand, from the economic perspective the system seems to be economically acceptable with a 7 years payback period, a positive net present value mounting to 31612.7$ and an internal rate of return of 13% which is greater than the 8% interest rate used in the economic evaluation.
Impact of Distributed Generation Model on Power Flow’s Parameters of Electrical Power System: A Case Study of Photovoltaic Based Distributed Generation Units
(Shahd Azzam Abed Allateef Sukkar, 2018-07-18) Sukkar, Shahd
In this thesis generalized regression neural network based model for photovoltaic based distributed generation units is proposed. The proposed model has two inputs which are solar radiation and ambient temperature, while, the output is the output current. Matlab environment is used to train, test and validate the proposed model. After that the developed model is applied to IEEE- 14 bus system so as to improve the voltage profile, decrease power losses and increase the reliability of the system. But the grid needs some modifications to make the addition is acceptable, the total power losses of the power system after these modifications are about 45.96 MW and 182.551 MVAr. The performance of the electrical power system with the proposed model of distributed generation unit is compared with the performance of the electrical power system considering a conventional model of the distributed generation unit that is talked about fixed power from the photovoltaic. Results show that Bus 4 is the suitable bus for an installation of distributed generation unit. Thus a photovoltaic system with capacity of 30 MWp is connected to the system by considering the proposed model and the conventional model (fixed power injection). It found that total real power losses of the system after adding the fixed distributed generation unit is about 37.288 MW. Meanwhile, the total reactive power losses are found to be 148.97 MVAr. On the other hand, by utilizing the proposed model (GRNN model), the total power losses of the system is found to be about 40.3 MW and 160 MVAr. Therefore, there is a difference of 3 MW between the two methods, Meanwhile using fixed output power for photovoltaic system will get an imaginary improvement because this method doesn’t take into account weather variations and absence of sun tonight , the utilization of conventional models for photovoltaic based distributed generation is not recommended as it exaggerates the improvement of the system and consequently affect negatively the reliability of the system
تحليل استهلاك الطاقة الكهربائية في مدينة نابلس "نحو استخدام تطبيقات المدن الذكية"
(جامعة النجاح الوطنية, 2019-01-23) مصطفى دعمي, صهيب وصفي; خليل, الدكتور شاكر
الملخص يعد توفر الطاقة الكهربائية من المحددات الرئيسية للتنمية الاقتصادية والازدهار بالمجتمع، ومع مرور الوقت والتطور السريع والابتكار التكنولوجي ازداد الطلب على الطاقة الكهربائية وتعددت أوجه إستخداماتها. تهتم هذه الدراسة بالتحليل الوصفي لإستهلاك الكهرباء في مدينة نابلس باستخدام برنامج نظم المعلومات الجغرافية GIS كأحد تطبيقات المدن الذكية، حيث تم تقسيم مدينة نابلس الى خمسة مناطق جغرافية تتزود كل منها بالطاقة الكهربائية من خلال نقطة ربط مستقلة وتم تحليل العوامل المؤثرة على استهلاك الكهرباء وهي مساحة منطقة نطاق الخدمة وعدد الافراد وعدد الاشتراكات الفعلية وتحليل النشاط الاقتصادي لهذه المناطق. واظهرت نتائج الدراسة أن نقطة ربط حوارة والتي تغطي المنطقة الشرقية من المدينة هي الاكثر استهلاكاً للكهرباء بحسب العوامل حيث بلغ معدل نصيب م² من الاستهلاك لنفس النقطة 7.7 ك.و/س وبالمقابل بلغ المعدل لكل المدينة 4.7 ك.و/س، بينما بلغ معدل نصيب الفرد السنوي 976 ك.و/س وبالمقابل بلغ معدل نصيب الفرد لكل المدينة 985ك.و/س، وتفسر معدلات الاستهلاك المرتفعة بوجود أحمال صناعية مرتفعة تغطي 26% من مساحة العناصر في منطقة نطاق الخدمة، اضافة لذلك وجود مناطق ذات كثافة السكانية مرتفعة مثل المخيمات بمساحة 8% من منطقة نطاق الخدمة، وتميز النشاط التجاري ايضا في المنطقة بنسبة 5% من منطقة نطاق الخدمة.
التأثير الفني والاقتصادي من استخدام أنظمة الخلايا الشمسية المربوطة على الشبكات الكهربائية في مراكز جهاز الدفاع المدني
(جامعة النجاح الوطنية, 2019-02-20) نبهان عبد الرزاق جلاد, تالة
فلسطين هي إحدى المناطق التي تعاني من عدم الاستقرار السياسي والاقتصادي واستمرار الاحتلال, وبسبب ظهور مشكلة الانقطاع المستمر للكهرباء في كافة محافظات الضفة ونظراً لزيادة الاحمال الكهربائية على الشبكات ونظراً للدور المهم والحيوي الذي تقوم به مراكز جهاز الدفاع المدني في تقديم الخدمات للمواطنين والاستهلاك العالي للتيار الكهربائي في المراكز كان لابد من البحث عن نظام طاقة بديل في توليد الكهرباء وهو استخدام الخلايا الشمسية الكهروضوئية نظرا لكفاءتها وباعتبارها مشاريع صديقة للبيئة وتحافظ عليها من التلوث. جاءت هذه الرسالة لتتناول موضوع استخدام انظمة الخلايا الشمسية في مراكز الدفاع المدني الفلسطيني وتحليل الاثر التقني والاقتصادي من استخدام الطاقة الشمسية في المراكز ومدى تأثيرها على خفض فواتير الكهرباء لمراكز الدفاع المدني الفلسطيني التي تتراوح قيمة فواتيرها ما بين IL (350-1100 ) شهرياً وتوضيح استهلاك مراكز الدفاع المدني الفلسطيني ووصف لمنحنيات الحمل الكهربائي لمعظم مراكز الدفاع المدني الفلسطيني. واختيار أفضل خيار للإمداد الكهربائي في كل من السيناريوهات وذلك من خلال توضيح إمكانات الطاقة الشمسية في فلسطين وشدة الاشعاع الشمسي وجميع البيانات الشمسية ذات الصلة في فلسطين وبعض المراكز المحددة اللازمة لدراستنا كحالات خاصة والتي تمثلت بمركز طوباس والرام وعنبتا وتحليل نتائج التوزيع الأمثل لموارد الطاقة في المراكز باستخدام برامج خاصة لتحسين تكلفة الطاقة في مراكز الضفة الغربية. كنتيجة للدارسة نظرا للتعريفة التجارية المرتفعة في الوقت الحاضر ونوعية الطاقة الشمسية في فلسطين، كذلك القوانين والتوجيهات الفلسطينية الأخيرة التي تحكم مشاريع الطاقة المتجددة، ترشدنا إلى التفكير أكثر في استخدام تعليمات صافي القياس لتغطية مراكز الدفاع المدني، حيث ان قيم القدرة القصوى المطلوبة من الأنظمة الكهروضوئية لمراكز الدفاع المدني في مدى يتراوح بين (19.2 – 38.4) kWp وبالتالي تحقق هذه الوفورات ما بين (22,100 – 43,000) IL في السنة للفواتير وخلال فترات زمنية لا تتجاوز 4 سنوات يمكن استرداد تكلفة المشاريع. اضافة الى الحد من مظاهر التلوث وفقا لمراكز الدفاع المدني الطاقة المولدة سنوياً من أنظمة الخلايا الشمسية (28.91 MWh/yr. – 57.82 MWh/yr.) والتي ستكون عادةً وفورات في ثاني أكسيد الكربون بما يتراوح (17.346 tons - 57.82 tons) سنوياً.
Utilization Landfill Gas from ZF Landfill for Electricity Generation
(جامعة النجاح الوطنية, 2019-12-24) Snouber, Ahlam Nwaeif
In this research, we have studied the feasibility of using anaerobic digestion technology of Municipality Solid Waste to produce biogas and generate electricity at Zahrat Al-Finjan Landfill in northern Palestine. Solid waste is one of the environmental problems in urban areas of Palestine. Municipal Solid Waste Reduction, Reuse and Recycling (MSW) are technologies for dealing with household solid waste but are not being used effectively in our country. Since MSW is very rich in energy, its use as a renewable energy source is one of the most important economic projects that the Palestinian Authority seeks to implement if its economic viability is proven and the financial resources will be available. The investigation results of energy efficiency and environmental impact of biogas utilization in ZF landfill are satisfactory enough both for electric energy production and for its contribution to greenhouse gas mitigation. This thesis has two main objectives. First, to determine whether active extraction of Zahrat Al- Finjan landfill gas would produce adequate electric power for utilization and grid connection. The second objective is to estimate the reduction of greenhouse gas emissions. However, to optimize the designing of a plant fed by biogas, it was very essential to quantify biogas production over several years. This research found that the average biogas production per year at Zahrat Al- Finjan landfill is more than 13 million cubic meters, enough to run 3.9 MW plants, and annual energy production of more than 34 GWh/year, and around 18 thousand tons of CO2 reduction per year.
Fault-Tolerant Unified Power Quality Conditioner with Active and Reactive Power Injection Capability using Multi-level Inverter and Photovoltaic Array
(جامعة النجاح الوطنية, 2020-07-22) العثمان, أحمد
إن وحدة التحكم بجودة القوى الكهربائية هي عبارة عن دمج بين وحدتي تحكم مختلفتين، الوحدتين هما عبارة عن وحدة موصلة على التوالي والأخرى على التوازي مع خطوط الضغط العالي من الشبكة. مما يجعلنا نستفيد من ميزة كل نظام على حدى. مما يساعد في تبديد الترددات غير المطلوبة من النظام الكهربائي وذلك عن طريق تنقية الإشارة الكهربائية لكل من الجهد والتيار مما يؤدي إلى تحسين جودة القدرة الكهربائية الخاصة بالشبكة. النظام المستدخدم في هذه الدراسة يتكون من 27 مرحلة مختلفة من عواكس القنطرة كيث أن هذا النظام ثلاثي الأطوار كل طور يتكون من قنطرة منفصلة وكل قنطرة يتم تغذيتها كهربائياً من مصفوفة من الخلايا الضوئية، حيث يقوم هذا النظام بضخ 12.5كيلو فولت أمبير من الطاقة الفعالة لخطوط الطاقة الكهربائية حيث يتم توفير 10 كيلو أمبير عن طريق العاكس الموصول على التوالي بينما 2.5 كيلو امبير عن طريق العاكس الموصول على التوازي. يتم توصي الخطوط الخارجة من العواكس إلى خطوط التوزيع بشكل مباشر بدون أي وسيط، بالإضافة إلى قدرة النظام إلى القضاء على الترددات الغير اساسية لكل من تيار وجهد المصدر الكهربائي فهذا النظام قادر على توليد قدرة فعالة وغير فعالة وحقنها في خطوط التوزيع الكهربائية. بالإضافة إلى ذلك يوجد نظام تخزين كهربائي عند نقطة ربط التيار المستمر حيث يتم شحنها من نظام الخلايا الضوئية ويتم التحكم بعملية الوصل بمتحكم شحن يعتمد على الوصول إلى نقطة القدرة العظمة في برمجته.
Development of an Expert System for Power Transformers Fault Diagnosis Using Random Forest Technique
(جامعة النجاح الوطنية, 2020-07-28) Arar, Ghazi
This research will contribute to the field of power system protection. As traditional protection has failed to overcome its limitations to classify and discriminate different statuses of transformer, a need has risen to find new techniques to solve the problem. In this thesis, ensemble techniques are used to solve this issue. Hence, the differential protection constructed by using ensemble techniques to provide protection element via a trip and no trip actions. And further, conditional monitoring functions are used to distinguish five different statuses of transformer including normal, inrush, over-excitation, current transformer-saturation and internal fault. By capturing practical transformer rating models for 20 different transformers with 5 different operating cases, 100 examples were provided as a data set to train and test models with 1600 observations. The 100 original and raw data were used to train random forest, then it has been validated with internal measures including out-of-bag error, margin, confusion matrix, and outliers. Afterward, an updated and weighted data set was generated to be used in training and testing random forest. OOB error and margin were captured for weighted examples to be compared with raw examples. Different train to test, which are 80-to-20 and 60-to-40, have been used to validate system strength and reliability. Moreover, a faster version of random forest models constructed with different sizes of data window included ¾, ½, and ¼ cycles, resulted in an accurate protection and high accurate conditional monitor. Besides, two different versions of random forest in terms of individual trees depth have been tested concerning the greedy and limited size. Boosting technique was also applied to both, original data set and weighted data set with different train to test ratio including 80-to-20 and 60-to-40 to validate the model. And yet, the model has been tested conditioned with optimum number of trees by using out-of-bag error and cross validation folds. Due to that, the variable importance was achieved by using the optimum number of trees. It is worth noting that the variable importance was captured by using ensemble techniques, and therefore conclusion for signal importance at different instances investigated. In conclusion, random forest and boosting have shown promising results and showed the ability to classify the suggested problem. Thus, it provides accurate, fast, and reliable results.
Electric Energy Consumption of West-Bank: Past, Present and Forecast until 2025 Considering a Partial Coverage by PV-Solar
(جامعة النجاح الوطنية, 2020-11-02) يوسف أحمد عنتري, علا
يعاني قطاع الطاقة الكهربائية في الضفة الغربية من مشاكل مختلفة، أكبرها سيطرة الاحتلال الإسرائيلي بشكل كامل على مصدر الكهرباء، مما يجعل قطاع الطاقة غير فعال لتلبية احتياجات المستهلكين. يهدف هذا البحث إلى دراسة نظام الطاقة بالكامل في الضفة الغربية من خلال الإضاءة على معوقات قطاع الطاقة، ثم التنبؤ بنسبة الزيادة في الطلب على الحمل إما ذروة الحمل أو استهلاك الطاقة، ويمكن استخدام هذه الأرقام في معرفة مقدار الطاقة التي نحتاجها في المستقبل. تمت الإشارة إلى الحمل المتوقع (ذروة الطلب واستهلاك الطاقة) بمتوسط معدل نمو قدره 4.67٪ و4.97٪ على التوالي حتى عام 2025. تعد الطاقة المتجددة من الحلول المهمة والتي تساعد على تغطية أجزاء من استهلاك الطاقة الكهربائية خاصة الطاقة الشمسية التي لها إمكانات حقيقية هنا في فلسطين، أدرجت في بحثي محطة طاقة كهروضوئية بقوة 30 ميجاوات كأحد التخطيطات المتوقعة للمستقبل القريب لتغطية الطاقة.
Design Unified Power Flow Compensator to Solve Power Quality for Maithaloon - Jenin's Medium Voltage Network
(An-Najah National University, 2020-12-10) دويكات, براء ايمن
The increasing of nonlinear loads leads to evaluate the harmonics generated from devices because they can harm the quality of power systems. In the distribution system, harmonics cause many problems such as voltage distortions, increasing of line current which will cause additional losses, overloading and overheating, failure of some electrical equipment as transformers, capacitors, and motors. Moreover, harmonics may cause interfering with telecommunication lines. This research will be done on real grid feed Maithaloon area which has a lot of nonlinear loads like water pumps, stone crushers, concrete factory and many other non-liner loads, also many of distributed generators interconnected with the grid. The Maithaloon electrical grid (Jenin-Palestine) grid fed from Israeli Electrical Company at the far end of long distribution transmission line operated at 33 kV and have rated capacity of about 5 MVA, the penetration due to the DG’s connected either on MV or LV side on the grid is very high (about 45-50%) compared to the standard recommendations. The field measurements of the current at medium voltage side show a high and un acceptable THD level varies between (26- 46%). The research based on FACTS devices specially the UPFC which designed and integrated to the real model of Maithaloon electrical grid and operated as adaptive device in MATLAB simulation model to eliminate the harmonics, improve the voltage levels and reduce the electrical losses. The design of UPFC built using the multilevel inverter technique and the controllers used the vector control theory (d-q method), and the DC source either renewable, capacitor banks or batteries. The results after the operating the UPFC show a huge improvement on the voltage levels (from 29kV to 34.5 kV) in addition to a good improvement on THD (8-9%). Moreover, the reduction on the losses in the network was considered and calculated in details.
PV multi-level based Grid
(2021) Shoubi Razan; Shashtare Zenat; Nofal Yasmeen
PHOTOVOLTAIC (PV) power supplied to the utility grid is gaining more and more visibility, while the world’s power demand is increasing. Solid state inverters have been shown to be the enabling technology for putting Photovoltic PV system into the grid. 2-level inverters are used to convert the DC voltage optained from the Photovoltic system to AC voltage fed to the utility. However, the use of 2-level inverters causes an increase in the Total Harmonic Distortion (THD) and other Power quality issues due to the harmonics injected by the such inverters. Increasing attention has been paid to multilevel dc/ac inverters in recent years to obtain output voltage of high quality. One of the more flexible topology is the asymmetric cascaded H-Bridge multilevel inverter, which will be employed in the project to improve the quality of the output voltage by reducing the harmonic contents. The project consists of two modules: power circuit and control circuit. The power circuit consists of two H_bridges forming an eight- level inverter. The ratio between DC voltage of the two H-Bridges will be 1:3. This will help to generate maximum number of levels and generate output near sinusoidal. The control circuit include the using of a microcontroller and current and voltage sensors to generate PWM signal to H-bridges and control the injection of real and reactive power inject to the grid. The whole structure of the project will be shown in Figure 1 ( Attached is a file showing the figure) . Experimental and simulation results using matlab /simulink will be presented to show the improving of the power quality using the multilevel inverter.
Optimal Sizing of a Standalone Photovoltaic Based Electrical Vehicle Charging Systems: A Case Study of Electrical Buses for Nablus-Ramallah Road
(جامعة النجاح الوطنية, 2021-01-19) عزام فخري سلامة, محمد
تبحث هذه الأطروحة في تصميم وتشغيل نظام شحن قائم على الطاقة الشمسية لسيارة كهربائية تعمل بالبطارية لتسير مسافة 50 كم. ويهدف الاقتراح إلى استبدال 110 مركبات ديزل قائمة بـ 39 حافلة كهربائية. يتم تقديم وتحليل العديد من سيناريوهات التشغيل لمحطات الشحن. وتشمل السيناريوهات منهجيتين مختلفتين لشحن البطاريات واحدة هجينة بين الحافلات الكهربائية ومركبات الديزل. تم في البداية تطوير نموذج طاقة للحافلات الكهربائية التي سوف يتم استخدامها. بعد ذلك، تم تحديد حمل الطاقة المطلوب والاحتياجات بما في ذلك عدد الرحلات اليومية، وعدد الركاب في الساعة واستهلاك الطاقة بالساعة على أساس النموذج المقدم والمعلومات التي تم الحصول عليها. تظهر النتائج أن 5.7 MWp من نظام الخلايا الشمسية مطلوب لتشغيل خط النقل هذا مع احتمال فقدان الحمل بنسبة 5٪ وتكلفة الرحلة لكل راكب 2.05 دولار أمريكي. تم التوصل الى فترة الاسترداد البسيطة لرأس مال النظام لتكون 10 سنوات، وتمثل هذه 40 ٪ من عمر النظام. ويقدر مقدار ثاني أكسيد الكربون من خلال النظام المقترح بـ 387 629 1 (كغم/سنة). وقد وجد أن الأثر الاجتماعي للمشروع المقترح مقبولاً في حين أن معظم الموظفين الحاليين سيحتفظون بوظائفهم برواتب أعلى بنحو 145% وساعات عمل أقل بنسبة 50%. وعلاوة على ذلك، من المتوقع أن يزيد المشروع المقترح في موثوقية عملية النقل واستدامتها. الكلمات المفتاحية: أجهزة الشحن الشمسية؛ الحافلات الكهربائية؛ نظام نظام فوتوفولتا الضوئي؛ النقل المحافظ على البيئة.
Improving Tubas Electrical Distribution Network Power Flow Parameters By Adding A Photovoltaic Based Distributed Generation Unit And A Medium Voltage Transmission Line
(جامعة النجاح الوطنية, 2021-01-20) الحاج, القسام
تقدم هذه الأطروحة مجموعة من الحلول المقترحة لحل مجموعة من المشاكل الموجودة في شبكة كهرباء طوباس, وقد تم اختيار هذه الحلول كأفضل حلول من حيث التطبيق العملي والتكلفة والمردود المادي لكل من هذه الحلول . كما تناولت هذه الأطروحة مجموعة من الحلول المقترحة من قبل شركة الكهرباء (شركة كهرباء طوباس) وتم وضع الحلول المقترحة في الأطروحة كحلول إضافية للحلول المقترحة من قبل الشركة وليست كبديل لها. وتجدر الإشارة إلى أن شبكة كهرباء طوباس يوجد بها عدة نقاط ربط بين الشبكة نفسها والشبكة القطرية وشركة كهرباء الشمال. وخلال هذه الأطروحة سيتم مناقشة كل هذه النقاط وتأثيرها على شبكة كهرباء طوباس. الأهداف المراد تحقيقها في هذه الرسالة, تحسين معايير الطاقة لشبكة كهرباء طوباس (خاصة منطقة الفارعة)، تصميم تقنية لتوزيع الطاقة المولدة من مولد مدينة الفارعة الجديد (مصدر جديد). باستخدام خط نقل جديد أو نظام PVs جديد، مما يوفر تيارًا كهربائيًا ثابتًا لبعض الأحمال في شبكة كهرباء طوباس، مما يقلل الضغط على بعض المحولات في شبكة كهرباء طوباس، ويحسن معامل القدرة (PF) لبعض أحمال معامل القدرة المنخفضة (PF)، توفير تيار كهربائي مستقر لبعض الأحمال الجديدة دون التأثير على الأحمال القديمة لبعض مناطق شبكة كهرباء طوباس، وتحسين وتطوير شبكة توزيع الكهرباء في طوباس من خلال تقليل استهلاك الكهرباء من IEC، وإنشاء وتصميم مولد جديد، مصدر جديد أو نظام كهروضوئي في الشبكة لدعم زيادة سعة الطاقة المستهلكة في الشبكة، مما يقلل النقص في ساعات الذروة لبعض مناطق شبكة طوباس وتغذية أماكن جديدة من شبكة شركة كهرباء الشمال.
Design and Assessment of Parabolic Trough Concentrated Solar System for Palestine: Case Study of Al-Arz Ice Cream Factory
(جامعة النجاح الوطنية, 2021-01-21) حسن عبد الفتاح خريشي, رند
في هذه الأطروحة ، تم اقتراح نظام جديد للطاقة المتجددة قائم على الطاقة الشمسية ومتكامل مع PTSCs (مجمعات الطاقة الشمسية ذات الأحواض المكافئة) ، وتحليله لمصنع البوظة الواقع في نابلس ، فلسطين. يشتمل النظام الحالي على نظام PTSC للتعاون مع غلاية التسخين في المصنع لتلبية الطلب على الطاقة الحرارية لتسخين خليط البوظة . تم إجراء تحليلات شاملة للطاقة في النظام لتحديد خصائص أداء العمليات الفعلية والمقترحة. بدلاً من موارد الطاقة التقليدية ، يفترض أن إنشاء هذا النوع من أنظمة الطاقة يوفر ظروف تشغيل أفضل من حيث الطاقة والاقتصاد والبيئة بشكل مستدام. أظهرت النتائج أن كمية الطاقة المنتجة من النظام الفعلي هي ) kW487.66( عند استهلاك (750.25 kW) ، بينما الطاقة التي يمكن ان يوفرها النظام المقترح 804 كيلوواط ساعة في اليوم , مع تقيده بمساحة معينة و هي 250 متر مربع ، و من ناحية أخرى يعمل النظام على توفير ما يقرب من 407.9 كجم من ثاني أكسيد الكربون يوميًا. الجدير بالذكر أنه تم إجراء تغييرات على بعض عوامل الحساسية مثل سعر الفائدة ، عمر المشروع ، الاستثمار الأولي للمشروع. حيث أن هذه التغييرات أثرت على نتائج المشروع بشكل عام ، بحيث أدت إلى جعل المشروع مجديًا اقتصاديًا في ظروف معينة ، بما في ذلك الوقت الذي يكون فيه عمر المشروع 30 عامًا ، قيمة الفائدة 8٪ ، وقيمة الاستثمار 2000 دولار لكل كيلو واط وفي سيناريو اخر عندما يكون عمر المشروع 25 سنه، قيمة الفائدة 8٪ والاستثمار الاولي لمشروع 2000 دولار لكل كيلو واط .

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