一种基于非线性电流跟踪算法的STATCOM相间电容电压平衡控制策略

Inter-phase Capacitive Voltage Balance Control Strategy for STATCOM Based on Nonlinear Current Tracking Algorithm

针对基于级联H桥拓扑结构的静止同步补偿器在传统控制框架下所产生的相间电容电压不平衡问题,采用一种新型混合调制方法并提出了一种全新的非线性分相电流控制策略。首先,基于六模块十三电平级联H桥拓扑结构,阐明新型混合调制的调制原理,并阐述适用于新型混合调制的相内电容电压均衡策略。其次,推导了静止同步补偿器在两相同步旋转坐标系下的控制模型,并分析指出采用dq解耦控制存在的相间电容电压不平衡问题。针对相间电容电压不平衡问题,提出基于三相静止坐标系下的电流分相控制策略,通过Lyapunov稳定性判据第二法推导并设计实现对交流指令电流无差跟踪的非线性电流控制器。最后,在Matlab/Simulink环境下搭建仿真模型。仿真结果表明,所提控制策略在不同条件下均能保持相间电容电压一致和稳定,且具有良好的动态响应特性。

In view of the inter-phase capacitive voltage unbalance of static synchronous compensator which is based on cascaded H-bridge topology under traditional control framework,a kind of new new hybrid modulation algorithm is adopted and a novel nonlinear current control algorithm is proposed in this paper.Firstly,the modulation principle of new hybrid modulator is described on the basis of six-module thirteen-level cascaded H-bridge topology and the same capacitive voltage balance strategy which is suitable for novel hybrid modulation is illustrated.Then,the control model of static synchronous compensator under two-phase synchronous rotating coordinate is derived and the inter-phase capacitive voltage unbalance problem of conventional dq decoupling control is indicated.Aiming at the inter-phase capacitive voltage unbalance,a separated phase current control strategy under three-phase static coordinate is proposed.A nonlinear current controller is derived and designed in accordance with the second method of Lyapunov stability criterion,which obtains error-free tracking effect to the alternative current reference.Finally,a simulation model is set up under Matlab/Simulink environment.The simulation results show that the proposed control strategy can not only keep the inter-phase capacitive voltage consistent and stable,but can also have perfect dynamic response characteristics at different conditions.