Nonlinear Resonance Suppression as Distorting and Saturating Source in Voltage and Current of Power Transformer: UPFC and STATCOM Performance Evaluation

摘要

Non linear resonance usually resonates in a network which has ferromagnetic cores. The coupling capacitance is mainly from the circuit breaker and cable capacitance. After the opening of the circuit breaker, the network is somehow still connected through the coupling capacitor. This results in the magnetization current of the ferromagnetic core to jump to saturation. The duration of ferroresonance is deeply relying on the coupling capacitance. The ferroresonance is decaying by disembarking total stored energy. After switching the circuit breaker off, the protecting relay and other protecting schemes are no longer in operation, and therefore the last protection step for saving a device, which is the circuit breaker is no longer operable. There is no reported method to mitigate this disruptive phenomenon. While protecting devices are somewhat useless, the fault point topology mutated by FACTS to control and decrease this phenomenon promises possible solution. This work attempts to damp the ferroresonance and to reduce the devastation effect using such FACTS devices such as UPFC and STATCOM. Modeling and simulation of ferroresonance were carried out using real transformer parameters and other power system related devices provided by the utilities. FACTS devices are able to improve power quality if they are timely switched at appropriate instants such as at the initiating moment of ferroresonance. The efficiency of FACTS devices was considered. UPFC is found to be the effective device to mitigate ferroresonance better than STATCOM.