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High efficiency and low-cost Static Frequency Changer (SFC) converters are widely used in electronic industry. SFC known as cycloconverter is installed to obtain variable output AC voltage or frequency. Fast dynamic response and slight size made these converters to occupy the potential space in switching world. Cycloconverter generates harmonics when connected to different types of loads. These harmonics pollute the purity of sinusoidal waveform and affect the quality of power system. Harmonic current is produced when an electrical device draws current in a non-sinusoidal manner. The harmonic voltage develops as harmonic current traverses the electrical system. Harmonic and current orders are inversely proportional to each other, respectively. These harmonics affect the execution of switching devices and causes breakdown of cable insulation, circuit breaker tripping, power transformer failures, limits on generator efficiency and UPS capacity. This paper comprises of odd harmonics that takes place in different load contiguous with cycloconverter. The 3rd, 5th, 7th and higher order harmonics are diagnosed by employing MATLAB platform. Simulation studies are depicted and proved the importance of single phase step down bridge - cycloconverter

The widespread use of single phase bidirectional converters in different applications is a real motivation to more and more interest to their monitoring and fault diagnosis. Generally, the conventional control loop of a single phase PWM converter uses both voltage and current sensors. Hence in case of sensor fault, the performances and the availability of the converter can be seriously compromised. This paper proposes a fast and robust sensor fault detection and isolation (FDI) and fault tolerant control (FTC) of a single phase PWM rectifier. The proposed FDI approach is based on residual generation. In order to improve the robustness of the proposed FDI algorithm and avoid false alarms, adaptive thresholds are used. Each residual remains under its threshold and crosses it if and only if the corresponding sensor is in fault state. Thus the faulty sensor can be easily distinguished and the uniqueness of signature of each faulty sensor is guaranteed. The control reconfiguration algorithm maintains the performances of the converter during post fault operating mode. The proposed method performances are analyzed by means of several simulations and experimental results.

The Directional Overcurrent Relays (DOCRs) coordination problem is of paramount importance for power system protection. This paper uses a new metaheuristic method called the Backtracking Search Algorithm (BSA) to solve the DOCRs coordination problem. The coordination problem has been formulated as an optimization problem to minimize the operating time of all the primary relays. The proposed algorithm has been implemented and applied to three test systems including the 6-bus, the 8-bus and the 15-bus test systems. Furthermore, a reliable approach has been developed to compare the results obtained using the proposed BSA with those obtained using other well-known metaheuristics. The results show the superiority of BSA over other methods in solving DOCRs coordination problems.

The increasing number of electronic power inverters connected to the electricity grid means that their synchronization with the electricity grid is becoming increasingly important. Typically, a phase locked loop (PLL) is an essential part of power inverters for achieving synchronization with the utility grid. Throughout the phase angle of the grid voltage, a reference signal is generated to synchronize the operating condition of the renewable energy production systems with the utility grid. This paper presents quantified analyses and comparisons of the main PLL techniques based on different structures for single-phase systems, and a comparative study of the enhancement for conventional phase-locked loop using four different methods, including, PLL with notch filter, PLL with notch filter based on fuzzy logic, PLL with a secondorder generalized integrator filter (SOGI-PLL), PLL with a second-order generalized integrator filter (SOGI-PLL) based on fuzzy logic. A comparison among these four studied improvements was conducted under normal operation condition. On the other hand, the performance of these filters was tested under three abnormal scenarios; Amplitude variations, amplitude and frequency variations, frequency and a phase jump variations. In addition, simulation results with PSIM software are developed to verify the performance and effectiveness of the strategy of each proposed method. Finally, experimental tests are used to extract the results and discuss the validity of the proposed quarter algorithms using the STM32F407 microcontroller board with phase angle and frequency estimation, which are visualized using a digital oscilloscope.

In this study, a novel method is presented for DC DC Cascaded boost converters design using PI controller block. This approach reinforces a same voltage source by using two or more cascade boost converter blocks simultaneously and is very effective in power transmission in renewable energy resources where they produce limited amount of power. In this converter, output voltage and current ripples are lower than 0.1%. One advantage of using this circuit compared to conventional boost converters is its long life because of input current division at the input blocks. A PI block controls voltage production confronting rapid load or input voltage changes by duty cycle changing and drive MOSFETs and restrict output voltage ripple. This circuit is simulated by MATLAB/SIMULINK and CADENCE for preparing to instruction and the results of the simulation confirmed the theoretical design. This design has implemented on a parallel structure with two blocks of cascaded boost converters at a laboratory scale.

Propagation of the magnetic field radiation in many residential areas within Riyadh City is high and sometimes exceed 300 mG. It has been found that the source of this radiation is underground cables that lies between the low voltage transformers and houses. The aim of this investigation is to find the sources of electromagnetic emissions and the reason for their emission and then develop solutions to avoid this problem. The outcomes of this survey indicated that the primary cause for the magnetic field radiation contamination results from the earthling of the neutral cable as that place for the earthling must be at one point before the low voltage transformer. This study has also provided solutions to avoid this problem through applying special earthling per dwelling unit availed by the client, where the company that provides the service of electricity test the efficiency of this earthling before opening the master breaker for the client . A complementary solution to this problem is to impose install breakers (MCCB) or (RCD) in the client box as a compulsory prerequisite for connecting electricity and electricity supplier install this breaker to prevent client overtakes. This study has concluded that many of the benefits can be achieved through applying these technical proposals to meet the aim of prevention of electromagnetic radiation resulting from technical faults in the electrical conductivity within the homes الانتشار الإشعاعي للمجال المغناطيسي في الأحياء السكنية داخل مدينة الرياض يعتبر مرتفعا و ذلك من خلال القراءات التي دونت حيث تتجاوز أحيانا 300 مل جاوس. لقد وجد أن مصدر هذه الإشعاعات هي كيابل التغذية الأرضية التي تقع بين محولات الجهد المنخفض و المنازل. و يهدف هذا البحث إلى تحديد مصادر الانبعاثات الكهرومغنطيسية و سبب انبعاثها و من ثم وضع حلول لتفادي هذه المشكلة. و قد أظهرت نتائج هذه الدراسة أن السبب الرئيسي للتلوث الإشعاعي بالمجال المغنطيسي ناتج من التأريض للكيبل المتعادل (Neutral) إذ أن مكان التأريض للكيبل المتعادل يجب أن يكون في نقطة واحدة عند محول الضغط المنخفض (Low voltage transformer). كما قدم هذا البحث حلولا لتفادي هذ المشكلة متمثلة في عمل تأريض خاص لكل وحدة سكنية من قبل العميل بحيث تكلف الشركة الموفرة للكهرباء بعمل اختبار لفعالية هذا التأريض قبل فتح قاطع التغذية الرئيسي للعميل. و كحل مكمل لهذه المشكلة يتم فرض تركيب قاطع (RCCB) أو (RCD) في صندوق العميل كمتطلب إلزامي لتوصيل الكهرباء و الشركة المزودة للكهرباء هي التي تقوم بتثبيت هذا القاطع لمنع تجاوزه بواسطة العميل. و قد خلصت هذه الدراسة إلى العديد من الفوائد التي يمكن أن تجني من خلال تطبيق هذه المقترحات التقنية للوصول إلى الهدف المنشود و هو الوقاية من الإشعاع الكهرمغناطيسي الناتج من الأخطاء التقنية في التوصيل الكهربائي داخل المنازل.

تم دراسة تغير تيار التفريغ عبر المجالات المغناطيسية المستعرضة (0 - 150 كاوس) في العمود الموجب للتفريغ ألتوهجي لغازي N 2 و CO 2 في مدى الضغوط من (0.75 إلى 7.5 تور). وقد وجد بان التيار يزداد بصورة تدريجية مع زيادة المجال المغناطيسي إلى أن يبلغ قيمة عظمى عند قيمة محددة من المجال المغناطيسي لكلا الغازين ولا تعتمد على قيمة الضغط لنفس التيار.

In sites with high soil resistivity such as deserts and mountainous terrains, designing and installing an effective grounding system is a challenging task. Therefore introduction of Bentonite into concrete mix of Ufer grounding at various proportions was done in a previous study and its steady state ground resistance performance was investigated. In that study, itwas found that 30% Bentonite-concrete mix is the optimum compound which yields the lowest average ground resistance with the least fluctuation as well. Subsequent study at site with high soil resistivity found that its performance is among the best compared with several conventional setups. In current work, such mix and the standard concrete mix were installed in five sites with varying soil resistivity to determine the correlation between ground resistance and localized soil resistivity. These correlations serve as a guide for future applications by engineers in designing grounding system using the best mix.