Electrical Power Engineering

Permanent URI for this collection

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

Browse

Now showing 1 - 20 of 26

A HYBRID FIREFLY-GENETIC ALGORITHM FOR THE OPTIMAL COORDINATION OF DIRECTIONAL OVERCURRENT RELAYS
(2023-02-19) Tareq Husam Foqh
Theoretical background: Directional overcurrent relays are applied for power system protection to ensure safe, reliable, and efficient operation. The coordination of directional overcurrent relays is non-linear and highly constrained optimization problem. The main goal of the optimization is to minimize the summation of operating times of primary relays, by setting optimal values for decision variables as time multiplier setting (TMS) and plug setting (PS). Aims: The main objective of this research is to develop a hybrid optimization algorithm which consists of modified firefly algorithm and genetic algorithm to find better solutions. Methodology: First, this study modified the original firefly to obtain a global solution by updating the firefly's brightness and to avoid the distance between individual fireflies from being too far. Additionally, the randomized movements were controlled to produce a high convergence rate. Second, the optimization problem is solved using standard genetic algorithm. Finally, the solution obtained from the modified firefly algorithm is used as the initial population for the standard genetic algorithm. The modified firefly algorithm, genetic algorithm and hybrid firefly-genetic algorithm have been tested on IEEE 3-bus, 8-bus, 9-bus and 15-bus networks. Main Results: The results indicate the effectiveness and superiority of the proposed algorithms in minimizing the overall operating time of primary relays compared to other algorithms mentioned in the literature for directional overcurrent relays coordination. Conclusion: Compared to modified firefly algorithm and standard genetic algorithm, the proposed hybrid algorithm has minimized coordination interval time between primary and backup relay pairs. Keywords: Directional overcurrent relays optimization, Hybrid algorithms, Firefly algorithm, Genetic Algorithm.
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.
ANALYSISAND IMPROVEMENT OF NABLUS ELECTRICAL DISTRIBUTION NETWORK BY ADDING A NEW CONNECTION POINT IN SARRA VILLAGE AND TWO TRANSFER SUB-STATIONS TO FEED THE NETWORK
(جامعة النجاح الوطنية, 2022-01-18) Qassab, Mohammad
Lack of electric power sources is one of main problems in Palestine since the population increased dramatically and the required electric power exceeded the permissible limit. In fact, since the Israeli-Electric Company is almost the primary source of electricity, therefore the electric power are limited. The Palestinians suffer from a shortage of electric power due to increasing of electrical power demand, but Israel Electric Corporation does not keeping up with the increasing demand. Nablus also suffers from a shortage of electric power due to the existence of new buildings and the sharp increase of population. In addition, the total electric power supplied to Nablus from connection points has the capacity of 65 MW, but electrical loads reached their peak especially in winter. Consequently, North Electrical Distribution company (NEDCO) cuts off some loads from certain areas in Nablus network for periods of time that exceed an hour per day in order to reduce the pressure on the other connection points in the same electrical network because loads exceed the permissible limit. This leads to failure in electrical transformers as well as in transmission lines and devices. At SARRA connection point, which is one of the connection points of Nablus, the capacity of the substation is 80 MW, and the used capacity is 40 MW. In this study, the researcher aims to examine the analysis and improvement of Nablus electrical distribution network by adding a new connection point in SARRA village and two distribution sub-stations to feed the network. There, a distribution substation was added in two areas with a capacity for 20 MW to each substation, named: Nablus Al-Jadida and An-Najah National Hospital. In fact, the electric power capacity has been raised to 105 MW for the city of Nablus. In this study, the problem was solved considerably by providing new areas with electric power and redistributing the loads from other connection points located in the Nablus city, especially in the eastern industrial area, and new overhead and underground electric transmission lines have been established. The value of the electric capacity supplied from the connection points to the city of Nablus has decreased, and there is a possibility of future expansion and supplying areas in the future due to the presence of electric energy capacity at the new connection points, according to the results found in this study. Also, economic feasibility of the project was prepared and the initial cost value has been calculated.
DESIGN A FUZZY LOGIC CONTROLLER TO CONTROL ACTIVE POWER FILTER FED BY MULTILEVEL INVERTER AND PHOTOVOLTAIC
(2023-09-11) Ghadeer Ahmad Abduh
New electrical systems commonly use nonlinear loads, which increase harmonic pollution in the primary power system. When power electronic equipment with semi-conductors is utilized, harmonic currents occur, affecting quality of power and generating non-sinusoidal currents taken from the AC sources. This result in a current discontinuity and an increase in the system's harmonics. Harmony in the power network generates a variety of issues, including voltage deformities at the Point of Common Coupling (PCC), altering peak and RMS values of line used, and a variety of other issues. In addition to the challenges caused by harmonic current, reactive power is another problem with the quality of the electricity in the power system. To improve the quality of the power delivered to the network, electrical filters must be employed to cancel harmonics and reactive power. The power quality is developed using a variety of filter topologies, including passive, active, and hybrid. A shunt active filter is employed in this project to increase the quality of the electric power. This active filter can perform a variety of tasks, including reducing harmonics, adjusting reactive energy, improving Power Factor (PF), inserting real power source. The primary goal of this project is to apply a fuzzy logic controller to optimize the performance of the Shunt Active Power Filter in order to lower harmonic distortion. To decrease the harmonic current and raise the power factor to unity, the Fuzzy Logic Controller for the three-phase Shunt Active Power Filter is intended to replace the Proportional Integral controller. The results were confirmed from the calculated values of the THD of the source currents. The THD was reduced from 16.67% before using the APF to 2.62 % after using the APF for PI controller and 16.67% to 1.42% for FLC. These results of the THD for FLC is even better than the results obtain of PI controller. MATLAB/SIMULINK has been used in this study to combine various renewable energy sources with a 27-level H-Bridge multi-level inverter with a shunt active power filter. The system has been built to function in a variety of operational scenarios. Keywords: Fuzzy Logic Controller, Shunt Active Power Filter, Photovoltaic,Multilevel Inverter, Total Harmonic Distortion.
Design And Analysis A Solar System For A Villa
(2022) Mohammad Yasin; Ayham Osta
There are numerous energy sources available, but their proportional utilization in the globe and in Palestine is not equal. We rely largely on electricity supplied by Qatari electricity businesses operating within the occupied country, which is delivered throughout Palestine via multiple connecting points. Installing solar cells and relying on them, (at least in part ), for daily use to minimize network pressure and deliver long-term economic savings Solar cells are designed in two examples for a villa in the Tulkarm area, one connected to the grid and the other disconnected from it. From shadow analysis to estimating the vacant spaces and loads in the house, we examined all of the design criteria. Also, based on studies and values taken over 20 years, including changing temperatures, the region was analyzed in terms of the sun's path throughout the year and the amount of radiation emitted by it, and finally, the used categories of inverters, batteries, solar cells, and everything else the system requires were chosen.
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 .
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.
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.
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.
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.
Impact of Battery Charging Station on Electrical Distribution Network: Study of the Harmonic Currents Impact and Mitigation Possibilities
(جامعة النجاح الوطنية, 2021-01-28) Omar, Reem Talat
This thesis focuses on the impacts of electrical vehicle charging stations on electrical power networks. The generated harmonic currents have negative impacts on the power system components causing more losses and voltage profile modifications. This thesis represents the impacts of PHEV charging stations in different configurations of electrical networks. Each charging station consists a three phase full wave rectifier with DC/DC converter for charging regulation. A simulation model was programmed based on MATLAB Simulink to perform harmonic analysis in two different electrical configurations AC and DC electrical networks. In AC distribution systems the impact of charging stations in three different modes shows that the voltage is reduced from 400 V to 336V while the total harmonic distortion of current and voltage reduced to 20.4% and 6.73% respectively. On the other hand, in DC electrical networks the total harmonic distortion of current and voltage are 24% and 10.9% respectively. Moreover, ETAP software was used to analyze the impacts of charging stations on electrical network in two different cases to localize the charging station downstream and upstream. Finally, in order to mitigate the harmonics, passive filter was designed to mitigate the harmonic currents which resulting to reduce that the total harmonic distortion of current and voltage reduced to 9.2% and 5.3% respectively.
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
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.
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.
Municipal Solid Waste to Energy Alternatives in the Northern West Bank: A Comparative Study
(جامعة النجاح الوطنية, 2021-09-26) فريج, صابرين
هدف البحث إلى إيجاد الطريقة الأفضل فاعلية وتأثيرًا من بين طريقة ترميد النفايات أو طريقة غاز الطمر عند التخلص من النفايات الصلبة وذلك بالنظر إلى المؤشرات من الناحية الاقتصادية من خلال معادلات مالية مفصّلة. بالإضافة إلى ذلك، تم تحديد المعيقات المحتمل تواجدها في كل طريقة، وكما أجريت أيضًا مقارنة بيئية بين الطرق الحالية المستخدمة في التخلص من النفايات الصلبة في مكب زهرة الفنجان في جنين (كدراسة حالة) والطرق المستقبلية المقترحة. وقد تم اعتبار انبعاث مكافئ ثاني أكسيد الكربون كمؤشر رئيسي في هذه المقارنة، وتم النظر في المنهجية المتبعة بخطواتها المتتالية، كما تمت مراجعة ومقارنة جميع التقارير الوطنية الحكومية بالإضافة إلى البيانات التي تم جمعها والمتعلقة بقطاعي الطاقة والنفايات. وعلى الرغم من أن السلطات الفلسطينية بذلت جهودًا جمة وتعاونت مع مؤسساتها في القطاع مثل سلطة الطاقة والموارد الوطنية الفلسطينية، وسلطة جودة البيئة، ووزارة الحكم المحلي لإيجاد حلول للمعيقات الحالية ولتنفيذ خطط استراتيجية فعّالة لإدارة مكب النفايات البلدية الحالي، إلا أنها لا تزال بحاجة إلى إجراء دراسات استقصائية تتعلق بالأداء الاقتصادي والبيئي لوضع تشريعات جديدة وطرق أفضل، لذا ستساعد هذه الدراسة المسؤولين في اتخاذ القرار المناسب للعثور على بدائل مناسبة ومحتملة عند التخلص من النفايات الصلبة وكيفية إنتاج الطاقة منها. إضافة إلى ما سبق تم حساب وعرض النتائج المتعلقة بالسيناريوهين في جداول وأرقام الفصل السابع؛ حيث تم تقدير نتائج سيناريوهات النموذج المالي من خلال حساب المؤشرات الاقتصادية مثل PW و AW و ROR و SIR و SPP و LCoE. ومن ثم تم التحقق من القيم والمؤشرات وتحليل الحساسية والخطورة مع تباين بعض المدخلات. أيضًا، تم حساب الطاقة المنتجة من محطة الحرق المقترحة في عملية ترميد النفايات وتبين أنها ستصل إلى 1411.33 جيجا لكل ساعة سنويا، بينما سوف تنتج طريقة غاز الطمر 118.87 جيجا لكل ساعة سنويًا. يجدر الإشارة أيضًا إلى أن توليد الطاقة من خلال هذه الطرق سوف تساهم في توفير جزء من الكهرباء اللازمة والمطلوبة في مناطق الضفة الغربية. علاوة على ذلك، تبين أنه في حال استخدام طريقة غاز الطمر فإن هذه الطريقة ستكون مربحة أكثر من طريقة ترميد النفايات عند قياس المؤشرات الاقتصادية، لكن من جهة أخرى سيكون لها آثار أكثر على البيئة حسب المؤشرات البيئية المقدّرة. ذلك يعني أن طريقة ترميد النفايات تؤثر بشكل أقل على البيئة، حيث أن الحرق تجنب انتاج مكافئ ثاني أكسيد الكربون بمقدار 1.082.492.7 طن سنويًا. بينما وجد أن مصانع غاز الطمر تجنب انتاج مكافئ ثاني أكسيد الكربون، سواء بشكل مباشر أو غير مباشر، بمقدار92,320.96 طنًا سنويًا بما في ذلك 1,144.4 طن من مكافئ ثاني أكسيد الكربون سنويًا بالإضافة إلى انبعاثات الميثان. توصي الدراسة باختيار تنفيذ طريقة ترميد النفايات، بما أنها وفق الدراسة، أكثر الحلول فعالية وربحًا من الناحية البيئية ومن ناحية كمية الطاقة المنتجة. أما من الناحية الاقتصادية فتعتبر طريقة غاز الطمر هي الأفضل ماديًا واقتصاديًا. وتشجع هذه الدراسة السلطات على الاستثمار في طريقة ترميد النفايات باعتباره الحل الأنسب، كما توصي بتصميم مرجل أفقي لاستخدامه في الحرق في المكبات وذلك بسبب تواجد المكبات على أرض منحدرة.
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
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.
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.

Browse

Browsing Electrical Power Engineering by Title

Results Per Page

Sort Options