基于磁控开关的高压无功补偿新方法

A Novel High-voltage Reactive Power Compensation Method Based on Magnetic-controlled Switch

目前，在10～35kV电压等级下对光伏发电、风力发电等无功需求变化范围大的负荷尚未有满意的动态无功补偿方案。当前常见的解决方案是高压晶闸管串联投切电容（thyristor switched capacitors，TSC）、晶闸管相控电抗（thyristor controlled reactor，TCR）、磁阀式可调电抗（magnetic-valve controllable reactor，MCR）以及静止同步补偿器（static synchronous compensator，STATCOM）。高压TSC和TCR需要大量晶闸管串联，成本高、可靠性差；MCR在轻载时有功损耗及谐波非常严重；STATCOM在高压场合下需要多组级联，可靠性较差，成本高。该文提出一种新方法，将双向晶闸管并联于变压器副边作投切元件，使变压器在励磁电抗和短路电抗之间转换，相当于无触点的“磁控开关”，从而实现对补偿电容器的投切。理论分析、仿真和实验均证实该方案具有暂态涌流小、响应速度快、损耗低、可靠性高的优点。

Currently, under the voltage grade from 10 kV to 35 kV, there＇s no satisfactory solution to the problem of dynamic reactive power compensation for load whose need for reactive power varies in a large range. The common solutions are high-voltage thyristor switched capacitors （HVTSC）, thyristor controlled reactor （TCR）, magnetic-valve controllable reactor （MCR）, and static synchronous compensator （STATCOM）. However, both HVTSC and TCR use many thyristor valves connected in series, which requires not only a highly qualified trigger system but also a large amount of thyristors that leads to huge cost. Meanwhile, MCR inevitably generates harmonics and consumes considerable power when the load is light. STATCOM consists of many cascaded inverter blocks under high voltage condition, resulting in the decrease of reliability and increase of cost. Therefore, a novel high voltage reactive power compensation method based on magnetic-controlled switch （MCS） is proposed in this paper. Triacs are connected in parallel with the secondary winding of a transformer as switching components, and in this way the impedance of the transformer at primary side exhibits either a small leakage reactance or a large excitation reactance, during which the transformer behaves like a contactless switch to implement the dynamic switch of compensation capacitors. Simulation and experiments have verified the advantages such as small transient inrush, rapid response speed, low loss, and high reliability.