Development of a large capacity static var compensator capable of high efficiency and quick response

近年来，采用GTO晶闸管的50-300MVA电压源逆变器组成的先进静态无功补偿器（ASVC）不仅可以提高功率因数，还可以稳定输电系统。asvc可以通过PWM或非PWM操作来调节逆变器输出电压的幅值，从而产生超前或滞后的无功功率。在大容量asvc在电力系统中的实际应用中，高效率和高可靠性是重中之重。在本研究中，作者开发并测试了一种由四串电压源非pwm逆变器组成的10kVA直流压控ASVC。通过分析和实验，阐明了以下几点。通过实验验证，通过增加反馈控制回路，实现了以往认为不可能实现的5ms时间常数的无功功率快速控制。实验结果与分析结果吻合较好。实验证明，作者提出的无损暂压电路工作良好，降低了开关损耗和电磁噪声。通过分析和实验指出，直流电容与线路电感之间可能发生串联或并联谐振，因此必须设计直流电容的容量以避免谐振。

In recent years, attention has been paid to advanced static var compensators (ASVC) of 50-300MVA consisting of voltage-source inverters using GTO thyristors not only for improving power factor but also for stabilizing transmission systems. The ASVCs can adjust the amplitude of output voltage of the inverters by means of PWM or non-PWM operation, thus producing either leading or lagging reactive power. In practical applications of large capacity ASVCs to power systems, high efficiency is the first priority as well as high reliability be.In this research, a dc voltage-controlled ASVC of 10kVA,consisting of quad-series voltage-source non-PWM inverters, was developed and tested by the authors. The following items are clarified by analysis and experiment.1.It was verified by experiment that quick control of reactive power with a time constant of 5ms, which had been considered to be impossible, was achieved by adding a feedback control loop. The experimental result agreed well with the analytical one.2.It was verified by experiment that a lossless snubbing circuit proposed by the authors works well, resulting in a reduction of switching losses and electromagnetic noises.3.It was pointed out by analysis and experiment that series or parallel resonance may occur between the dc capacitor and line inductance so that the capacity of the dc capacitor has to be designed to avoid the resonance.