Published Paper Details:

Abstract Background And State Of Art With the widespread use of electronic equipment, loads are becoming more sensitive and less tolerant of short-term voltage disturbances in the form of voltage sag. Custom power is a technology-driven product and service solution which embraces a family of devices to provide power-quality enhancement functions. Among the several novel custom-power devices, the dynamic voltage restorer (DVR) is the most technically advanced and economical device for voltage-sag mitigation in distribution systems. The conventional DVR functions by injecting AC voltages in series with the incoming three-phase network, the purpose of which is to improve voltage quality by the way of adjustment in voltage magnitude, wave shape, and phase shift. These attributes of the load voltage are very important as they can affect the performance of the protected load. The voltage-sag compensation involves injection of real and reactive power to the distribution system and this determines the capacity of the energy storage device required in the restoration scheme. The reactive power requirement can be generated electronically within the voltage source inverter of the DVR. An external energy storage is necessary to meet the real-power requirement. Thus, the maximum amount of real power that can be supplied to the load during voltage-sag compensation is a deciding factor to analyze the capability of a DVR, especially for mitigating long-duration voltage sag. Voltage injection with an appropriate phase advance with respect to source side voltage can reduce the energy consumption. However, the energy requirement cannot be met by the application of such phase-advance technique alone for mitigating deep sag of long duration, as it is merely a way of optimizing existing energy storage. If the DC link of the DVR can be replenished dynamically by some means, the DVR will be capable of mitigating deep sag with long durations. Keywords: DVR, IDVR, FACTS, DSTATCOM, UPFC, DPFC, PWM