不平衡负载下三相四线制DSTATCOM无锁相环电流检测

Detection for Three-phase Four-wire DSTATCOM Without Phase-locked Loop Current Under Unbalanced Load

传统DSTATCOM电流检测采用的是dq变换法,在检测三相四线制负载电流的不平衡和无功分量会存在一些缺陷。本文提出了一种无锁相环及坐标变换电流检测方法。在αβ静止坐标系下,依据通用矢量定义及归一化方法,计算出有功电压和无功电压单位分量。将负载电流进行正负序分解和相位纠正来获取基波正序有功电流分量,从而获得所需补偿的不平衡和无功分量总和。该算法无需锁相环和坐标变换,算法简单,易于实现。通过控制DSTATCOM输出所需的补偿电流,实现对三相电网电流的补偿。仿真和实验结果表明了该方法具有可行性和有效性。

The dq transformation method is used in traditional DSTATCOM current detection,which has some defect in detecting the unbalanced and reactive power component of the three-phase four-wire load current.In this paper,a kind of current detection method without phase-lock loop and coordinate transformation is proposed.In the ap static coordinate,the active and reactive voltage unit vector is calculated in accordance with general vector definition and vector unitization.The load current is subject to positive and negative sequence separation and phase correction of load current are carried out to obtain the positive sequence active current component of base wave,thereby obtaining the sum of the unbalanced and reactive components of the required compensation.This algorithm does not require phase-locked loops and coordinate transformation,and the algorithm is simple and easy to implement.It can realize the compensation of three phase network current by controlling the DSTATCOM output required compensation current.Simulation and experiment results verify the feasibility and effectiveness of the proposed strategy.