隔离开关开合母线充电电流方式3试验电压升高问题分析

Study of Voltage Increase in Test Duty 3 of Bus-charging Currents Switching by Disconnector

在隔离开关开合母线充电电流试验方式3电流开合能力试验中,由于试验变压器的阻抗高,会出现试验电压明显升高的现象,标准规定电压升高不应超过10%。为了使试验条件满足标准要求,理论分析了方式3试验电压升高的原因;采用EMTP-ATP软件对提出的并联电容和并联电感两种不同试验回路进行了仿真研究。研究结果表明:在并联电容试验回路中选取合适的并联电容,使负载电容接入前后回路工作在工频串联谐振点两侧合适位置,可使输出电压压升满足标准要求,但要求变压器额定输出电流较大;在并联电感试验回路中利用并联电感和负载电容发生工频并联谐振呈现出无限大阻抗的特性,可以限制输出电压升高,但必须满足关合同期性。

Because of the high impedance of test transformer, test voltage increase may occur in test duty 3 of bus-charging currents switching by disconnector, and a voltage increase limit of 10% is required by related standards. In order to meet the above test requirement, the reasons of vohage increase in test duty 3 are analysed, and both shunt capacitor test circuit and shunt inductor test circuit are studied by EMTP-ATP simulation in this paper. The simulation results show that： by selecting an appropriate shunt capacitor value and working on two suitable points on both sides of power frequency series resonance point before and after the connection of the load capacitor, shunt capacitor test circuit can meet the requirement of standards, but with a higher output current of test transformer. Take the advantage of the infinite impedance of power frequency parallel resonance occurring between shunt inductor and load capacitor, shunt inductor test circuit can limit voltage increasing, but close synchronism must be satisfied.