四桥臂SVG改进电流检测方法及控制策略

目前,静止无功发生器广泛用于解决低压配电网中三相电流不平衡问题。本文对四桥臂静止无功发生器电流检测算法和控制策略进行了改进,在dq0检测算法基础上分离电流零序分量,通过dq变换得到负序分量,从而实现不平衡分量的快速检测。同时通过设计双dq变换锁相环精确锁定电网电压相位。采用该检测算法和自适应滞环电流控制方式设计出四桥臂静止无功发生器样机。通过仿真和实验验证,改进检测算法具有更加准确快速的特点,自适应滞环控制的引入也有效改善了传统滞环控制中频率不稳定的缺陷。

Improved Current Detection Method and Control Strategy for Four-leg SVG

At present,static var generator(SVG)is widely used to solve the problem of unbalanced three-phase current in low-voltage distribution network.In this paper,the current detection algorithm and control strategy for a four-leg SVG were improved.First,the zero-sequence component of unbalanced current was separated based on dq0 detection algorithm. Then,the negative-sequence component was obtained through dq transformation,and the fast detection of unbalanced components was realized accordingly.At the same time,the phase locked loop(PLL)based on the transfor. mation of double-dq frame was designed to precisely lock the phase of grid voltage.Using this detection algorithm and adaptive hysteresis current control mode,a prototype of improved four-leg SVG was designed.Both simulation and experimental results demonstrated that the improved detection algorithm was more accurate and faster;meanwhile,the introduction of adaptive hysteresis control effectively overcame the deficiency of unstable frequency in the traditional hysteresis control.