柔性接地补偿电流离散域矢量控制策略研究

Study of the discrete vector controller for current regulation of flexible grounding compensation method

柔性接地通过电力电子变流器补偿单相接地故障电流的有功和谐波分量,实现对故障电流的全补偿,从而有利于接地点电弧的快速熄灭,因此柔性接地在配电网具有重要的应用前景。针对柔性接地有功与谐波电流控制,通过建立电力电子变流器的离散模型,直接考虑数字控制的一拍延时,设计了离散矢量电流控制器,在静止坐标系实现了对交流信号的无静差调节。针对所提电流控制器,通过离散域根轨迹分析,提出了临界阻尼参数设计方法,优化暂态响应避免了过补偿。仿真结果验证了所提控制器与设计方法的有效性。

The active and high-frequency harmonic current are compensated by introducing power electronics converter of the flexible grounding,which achieves full compensation of the single-phase to earth current to achieve a fast arc extinction.Thus,the flexible grounding is promising in the distribution network.Regarding the active and harmonic current control,this paper proposes to design the controller in the discrete-time domain based on the discrete model of the plant,which deals with the onesample delay directly.The discrete complex current controller is developed which achieves AC current regulation in the stationary reference frame without steady-state error.With regard to the proposed controller,a tuning method based on critical damping is proposed based on the discrete root locus analysis,which avoids overshoot and optimizes the settling time.The simulation results have verified the effectiveness of the proposed controller and the tuning method.