基于模型预测方法的MMC环流抑制策略
A strategy of circulation current suppressing for modular multilevel converter based on model predictive control method

摘要 为了抑制模块化多电平换流器(MMC)的相间环流,提出一种基于模型预测(MPC)方法的环流抑制策略．该方法在传统系统控制的基础上,结合最近电平逼近调制,通过检测环流方向,利用模型预测实现模块数的实时更新,从而达到定量抑制二倍频环流的目的．和传统环流抑制策略相比,该方法不必考虑环流频率特性,同时省去了复杂的参数设计,实现简单,更适用于MMC模块数较多的工程实际情况．在PSCAD中对上述控制策略进行了仿真验证,结果表明:所提策略可以定量抑制MMC相间环流,从而有效减少桥臂电流畸变和子模块电压波动.
Abstract： In order to suppress the interphase circulating current existing in the modular multilevel converter (MMC), a circulating current suppressed model in predictive control (MPC) is presented. It is built on basis of the traditional control system. Combined with the approximation modulation of the nearest level, through testing the circulating current direction, the second harmonic circulating current can be suppressed quantitatively by updating the input module in the real-time Compared with the traditional method, there is no need for the proposed method to consider the frequency characteristics of the circulating current, the complex parameters design is eliminated, and the realization is simple. Meanwhile, the proposed method is more suitable for the practical engineering which has a large number of submodules. The simulation has been carried out in the PSCAD. The results show that the proposed strategy can suppress circulating current effectively so that the arm current distortion and the module voltage fluctuation can be greatly reduced.