In this paper, we propose a very simple technique that offers an extra degree of freedom to optimize the design of a tire dustbased absorber with reduced height. Cladding is a technique that is used to enhance the surface properties of a part, and it has been used in many applications for many years. In this technique, a clad layer is created on the core material, and the composition of the clad layer is adjusted to enhance the performance of the core material. We use a rice husk-clad layer to enhance the impedance matching characteristics of the low-loss, tire-dust core, microwave absorber. The overall design is a two-layer, geometrically-tapered, pyramidal structure composed of two lossy waste materials. Our main goal was to make the front surface less reflective (impedance matched), hence the material of the outer layer (clad) of the absorber was selected on the basis of the analysis of the dielectric properties of the candidate materials. Optimum thickness of the clad was obtained by using CST simulation software and found to be 12 mm, for which a reflectivity performance of less than −20 dB was
In this paper, a modified variable step Incremental Conductance (VS-InCond) algorithm integrated with modified pq theory and double-band hysteresis current control (PQ-DBHCC) is proposed for the implementation on a single-stage single-phase grid-tied photovoltaic (PV) inverter system. As the single-phase inverter in a grid-tied PV system receives varying DC voltage from PV modules, the PQ-DBHCC strategy is deployed to regulate the ac output voltage along with its capability to deliver the maximum power during onload conditions. VS-InCond algorithm and DC-link capacitor are used as the interface between the PV modules and the inverter for tracking maximum power point. Furthermore, the PQ-DBHCC strategy also controls active and reactive power between inverter, load, and grid. The simulation results obtained from MATLAB Simulink software show that PQ-DBHCC strategy is capable of achieving the desired fixed DC voltage at inverter input and maintaining the maximum power point tracking, even under varying environmental conditions and load variations. The inverter ac output has a steady 230 Vrms at 50 Hz frequency. The total harmonic distortions (THDs) of output ac current and ac voltage are observed to be less than 5%, as recommended in IEEE 519 standard. Additionally, during full load conditions, the proposed system successfully delivers 95% of the theoretical maximum power from PV modules.
DC-DC converters are widely used in many applications such as power supplies, PV system, renewable energy systems and industrial applications. One of the main problems in dc-dc converters is the switching loss which affects efficiency and also the power density of the converter. To alleviate the switching loss problem this paper proposes novel soft switching PWM isolated dc-dc converters topology. The proposed full bridge dc-dc converter with active auxiliary circuit is designed and tested with full-bridge rectifier diode. The proposed converter is designed and evaluated in term of soft switching. In the proposed topology, the soft switching operations are achieved by charging and discharging process of the capacitor and additional switches. In the proposed topology, all the power switches operate under soft-switching conditions. Therefore, the overall switching loss of the power switches is greatly reduced. The output voltage of the converter is varied by PWM control. The effectiveness of the new converter topology is evaluated by experimental results of a laboratory scale down prototype. The obtained experimental results are found agreed with theoretical and soft switching is achieved.
Abstract-This project presents the development of Photovoltaic (PV) push-pull inverter for alternating current (AC) application. There are two main systems in this project which is the PV system and the inverter system. The photovoltaic system consists of the PV panel which is used to seep sunshine to recharge the battery and the solar charger controller circuit that prevent battery from surpluses voltage is connected between solar PV and battery. While the push-pull inverter play a pivotal role in switching from direct current (DC) voltage to AC voltage for the inverter system. Then the AC voltage rose to 230 V by using transformer. The push-pull inverter switching is controlled by a multi-vibrator driver circuit. This project used two light emitting diode (LED) light bulb as an AC load and Metal Oxide Semiconductor Field Effect Transistor (MOSFETs) as the power switches. This project had been analysed through software and hardware prototype for comparison purposed. The efficiency of ideal system that obtains from software simulation is 94.9% while for the hardware prototype is nearly to 95%. While the total harmonic distortion (THD) for both voltage and current is 48.32% from software simulation and 47.9% from hardware prototype analysis. The results have been found in good agreement with the analysis presented in this paper.
Electrical Power System protection is required to protectboth the user and the system equipment itself fromany fault, hence electrical power system is not allowed to operate without any protection devices installed. Power System fault is defined as the undesirable condition that occurs in the power system. Some of these undesirable conditions are short circuit, current leakage, ground faultand over-under voltage. With the increasing loads, voltages and short-circuit duty in power plant, over voltage protection has become more important today. Here, the component that had been used is PIC 16F877a microcontroller to control the whole system and especially on the circuit breakers as well as the LCT display unit is used to display the voltage level and type of generator that used to serve the load. Sensors are used to measure both thevoltage and the load. The controlled digital signal from PIC microcontroller is converted by using the digital analog converter to control the whole circuit. Thus a device called protective relay is created to meet this requirement. The protective relay is mostlyoften coupled with circuit breaker in a way that it can isolate the abnormal condition in the system.
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