一种新型动态无功补偿器的控制算法

Control strategy for dynamic var compensation

针对无功动态补偿问题,通过分析单相系统结构原理,提出一种新型的基于直流侧电容电压控制和系统无功电流反馈控制的算法,直接对装置输出的电流进行控制,避开监测有功和无功电流分量的繁琐过程,简化了监测谐波的过程。所提出算法的控制目标是使补偿装置发出的电流为系统的无功电流,该算法包括电流和电压2个反馈环。电流环采用滞环比较的方式,将计算得到的目标电流和补偿装置实际输出的电流进行闭环比较;电压环采用周期控制思想。通过说明直流侧电压和变流器两侧功率传输的关系,推导出损耗电流与直流侧电压的变化关系公式;提出损耗有功电流和负荷无功电流的计算方法,以及直流侧电压的控制策略;数值仿真计算和动态模拟实验结果表明该算法无功补偿效果良好。

By analyzing the principle of the single-phase system structure, a strategy based on DC voltage control and reactive current feedback control is presented for dynamic var compensation, which directly control the output current of equipment to avoid the detection of active and reactive components and harmonics. The control objective of algorithm is to make the output current of equipment the reactive current of system. The current feedback loop with hysteresis compares the calculated reference current the output current of equipment while the voltage feedback loop applies the periodic control concept. The relationship between the DC; voltage and the power transfer at both sides of converter are analyzed and the formula of loss current related to DC voltage is deduced. A method for calculating the loss active current and load reactive current as well as the DC voltage control strategy is presented. Both simulative and experimental results show its good performance.