负载不平衡下D-STATCOM控制策略的仿真研究

通过分析建立配电网静止同步补偿器(D-STATCOM)在负载不平衡时各序等效电路中的数学模型，提出了将反馈线性化同时应用于正序、负序模型的控制策略。针对三相三线制下负载不平衡时电流可分解为正、负序分量的特点，分别在正、负序同步旋转坐标下进行补偿。其中，正序控制使装置发出负载需要的无功电流，提高功率因数；负序控制用于补偿由于负载不平衡出现的负序电流，从而使电网侧电流平衡达到国标要求。最后在PSCAD中搭建了10 Mvar/10 kV D-STATCOM系统进行仿真验证，证明了该控制策略补偿负载不平衡的同时能发出满足要求的无功功率，并且在电网侧出现超过国标的不平衡时仍能达到较理想的效果，显示出此控制策略的有效性。

Simulation study of the control strategy of D-STATCOM in compensating unbalance load

The mathematical model of distribution static synchronous compensator (D-STATCOM) in each sequence equivalent circuit of unbalanced load is established and the feedback linearization applied to both the positive and negative sequence mathematical model is proposed. The three-phase three-wire unbalanced load current can be decomposed into the positive and negative sequence component, so they can be compensated in the synchronous rotating coordinates system of positive and negative sequence respectively. The positive sequence control makes D-STATCOM generate reactive current required by the load, improving the power factor. The negative sequence control is used to compensate the negative sequence current due to load unbalance in order to balance the grid side current and meet the requirements of National standard. At last, a 10 Mvar/10 kV D-STATCOM system is built in PSCAD, and the simulation results prove that the control strategy can compensate the load unbalance and generate reactive current required by the load at the same time. Furthermore, when the voltage unbalance in the grid side exceeds the national standard, the control strategy can also achieve the desired results, showing the effectiveness.