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العنوان
REACTIVE POWER CONTROL FOR VOLTAGE FLUCTUATIONS MITIGATION AND POWER LOSS REDUCTION UNDER HIGH PHOTOVOLTAIC PENETRATION IN THE EGYPTIAN DISTRIBUTION NETWORKS\
المؤلف
Darwish,Elham Mohamed Moustafa
هيئة الاعداد
باحث / Elham Mohamed Moustafa Darwish
مشرف / Soliman Mohamed El-Debeiky
مشرف / Ahmed Mohamed Atallah
مشرف / Hany M.Hasanien
تاريخ النشر
2018.
عدد الصفحات
87p.:
اللغة
الإنجليزية
الدرجة
الدكتوراه
التخصص
الهندسة الكهربائية والالكترونية
تاريخ الإجازة
1/1/2018
مكان الإجازة
جامعة عين شمس - كلية الهندسة - القوى والآلات الكهربية
الفهرس
Only 14 pages are availabe for public view

from 105

from 105

Abstract

The increasing penetration levels of distributed photovoltaic (PV) generation in the Egyptian Electrical Distribution Networks presents many challenges and opportunities for the Distribution Utilities. In practice, it has been found that several problems arise, with the ever increasing PV penetration at a distribution system and connected with the low voltage (LV) grid.
One of the main troubles is the voltage fluctuations at the distribution network buses. Further the voltage DROP and the power losses increase. Therefore, the controlled PV systems that are connected to the grid can participate to enhance the voltage especially at the grid end, keeping the voltage at accepted value.
Thus, this thesis focuses on the optimal methods to controlling line voltage of distribution grids especially with the PV generation penetration, without need to infrastructure, also, this thesis illustrates the impacting of PVs spread on distribution transformer performance, and lifetime under these conditions Here, the system is simulated using the MATLAB/Simulink and the study is carried out using several methods.
By utilizing a controlled solar inverter, the reactive power (Q) control could be achieved as instituted by certain network codes. This method, which is based on the grid voltage profile for locations – dependent of power factor (PF), setting premium, could be allocated to the whole solar inverters. The main target is to mitigate unnecessary Q absorption. This method combines two droop functions the PF- active power (P) and the Q - V strategies. The performance for each inverter, is to compare with the output voltage and the injected reactive power that is controlled. Hence, the enhancement of the voltage profile at an appointed bus can decrease the total losses, saving the consumed power and thus augment the system capacity.
For the enhancement of the performance of the described PV system, the PV inverter is fully controlled by the proportional plus integral (PI) controller through a cascade control scheme. The salient feature of this study is the optimum design of the PI controller using the novel Whale Optimization Algorithm (WOA). The main objective is to get the optimal Maximum Percentage Under Shoot (MPUS) as compared with that obtained by using the Genetic Algorithm (GAs) and trial and error methods.
Further, the transformer is one of the most valuable components of the distribution systems. Therefore, this study focuses on the impact of the rooftop PV system that injects a maximum of 100 kW to the LV grid on the performance of the oil-immersed distribution transformer of 500 kVA, 22/0.4 kV Dyn 11 by using real data. The rest of the transformer capacity is assumed loaded by balanced normal loads. The results are then compared with the results of the simulated model values, with several scenarios for different loadings of the transformer up to the maximum power of the PV arrays, thus, about 20% of the transformer full load rating. Simulation is carried out by the MATLAB/Simulink program under various atmospheric conditions. The study supposed each PV inverter supplies the network with 10 kW reverse power flow. A thermal model is adopted using the measurements of the reactive power and the temperature over the twenty hours of days along eleven months, from 1 January to 30 November 2015, based on the 15 minutes interval and captures the impacting of the installed PV arrays variability at this time. The results for both real measurements and simulated results have been found very close. This denotes the precision of the simulation model.
Furthermore this thesis, proves that the PVs units are extending the useful life time for the distribution transformers. This can be ascribed to that the existence of the PVs relieve the load rating of the transformer. Hence the study shows improving effect on the transformer insulation. Also, PVs reduce the daily top oil temperature, hot spot temperature. Thus, extending the transformer life time. Thus, improvements depend on the load rating, the ambient temperature and the PV penetration level.