Study And Simulation Calculation Of Overvoltage And Overcurrent On Reactive Compensation Capacitors In Power Distribution Networks

Reactive compensation capacitors are applied at large in power distribution networks . They must be switched off or on frequent in order to accord with the changing reactive load. When capacitors are switching on overvoltage and overcurrent would emerge. Even higer overvoltage and overcurrent would occur in the process of switching off the capacitors if the arc reignited. Sometimes there are harmonics in system , the capacitors may magnify the harmonic current and finally the capacitors or the current-limiting reactors may be damaged by the overcurrent .So it is necessary to study how the overvoltage and overcurrent occur and how the influence factors work .In this paper, a systemic simulation using Aternative Transient Program (ATP) is presented to simulate the process of operation on capacitors. The conclusion is that: When switching on capacitors , the voltage on bus is higer, or the system short circuit capacity is greater,the overcurrent is higher; The inductance of current-limiting reactors is smaller, the overcurrent is higher. The capacity of capacitors is larger, the overcurrent is higher . If there are no current-limiting reactors, the overcurrent which is caused by switching the secondly capacitors will be much higher than that of switching the first one. The paper studies the overvoltage and overcurrent caused by reigniting and the factors.This paper presents some correlation curves connected system parameters with overvoltage and overcurrent, and some representative wave forms diagrams about overvoltage and overcurrent.Then some low voltage modle simulation tests are presented in this paper. The results of tests are consistent with the result of simulation.