الفهرس 
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Abstract
In this thesis a modified variable reactance compensation, by using a series controlled capacitor for load voltage stabilization is proposed. Series controlled capacitor is used to eliminate the load and supply inductance effect, without any discontinuity in the supply current. The proposed system operates for load voltage stabilization with static or dynamic loads. Differential equations describing the system operation in different modes of operation are given. A drive circuit that generates two groups of pulses to control the IGBT’s operation is designed and implemented. A closed-loop voltage control with a Proportional-Integral (PI)Controller, for stabilizing load voltage with static and with dynamic loads is developed. Simulation results of the system under open and closed-loop operation are obtained using the matlab/simulink software. Power circuits of the proposed system, PI controller and drive circuits are built and tested in the laboratory to obtain the experimental results. The proposed system improves the input power factor and can operate as a voltage controller to regulate the load voltage, without discontinuity in the current. The dynamic performance of the load in both transient and steady-state operation is studied. Also the proposed system, with insertion technique, is used for mitigation of voltage sag; the load voltage can be stabilized over a wide range, taking the supply impedance into account. The load voltage can be controlled by changing the injected voltage, or changing the transformer ratio of the inserted transformer to obtain any required voltage, which it can be controlled by controlling the duty ratio, so the load voltage can be conserved stabilized at constant value. Performance of a series ac motor (fed by the proposed system) is studied in both transient and steady-state operation.