斜桥变电所铁磁谐振过电压的仿真研究

为提高嘉兴电力局配电网面对铁磁谐振过电压的安全性,以斜桥变电所10kV配电网为模型,利用EMTP程序仿真分析了在TV高压侧中性点接非线性电阻、串单相TV(4TV方式)及TV开口三角绕组接阻尼电阻或分频消谐装置等多种消谐措施。结果表明非线性电阻能保持相电压稳定及抑制涌流,正温度系数热敏电阻和3次谐波滤波器可较好解决零序电压的偏高;4TV方式一次侧电流和零序电流过大等问题。还分析了分频消谐装置在实际运行中不能很好消谐的原因。仿真分析结果对提高配电网的供电安全可靠性具有很好的实用价值。

Simulation Study of Measures for Ferroresonance Elimination in Xieqiao Substation

In the neutral ungrounded power distribution system of Jiaxing power system,ferroresonance has taken place several times in the past few years.This phenomenon may cause dangerous over currents and over voltages,resulting in unwanted tripping of the protection relays and automatic devices,which has been impacting the safe operation of power system severely.This paper models on Xieqiao substation 10kV power distribution system in Jiaxing.Simulations on several prevention measures are performed with Electromagnetic Transients Program(EMTP),including connecting a nonlinear resistance to the neutral point of high voltage side of three-phase TV,connecting single-phase TV to the neutral point of high voltage side of three-phase TV which is always called 4TV mode,connecting a damping resistance or subharmonic ferroresonance eliminator to the broken delta connection of the secondary assistant windings of three-phase TV,et al.Results show that ferroresonance is effectively eliminated when the neutral point of high voltage side of three-phase TV is grounded through a nonlinear resistance,which not only keep the phase voltages steady but also restrain the inrush currents flowing in the high voltage windings of three-phase TV in the period of earth faults and then at the instant of disappearance.Positive temperature coefficient(PTC) thermistor and triple frequency harmonic filter can reduce zero sequence voltage when a nonlinear resistance is used to prevent ferroresonance.Unfortunately,disadvantages exist in the 4TV mode.The transient currents circulating in the high voltage windings of three-phase TV at the instant of disappearance of earth faults are still too large.So the current is flowing in the closed delta connection of the secondary assistant windings of three-phase TV.In addition,reasons why the subharmonic ferroresonance eliminator can't prevent ferroresonance effectively are analyzed.The results of this paper are proved to be of great use in improving the reliability of power distribution system.