基于滑模控制的角形级联静止同步补偿器快速不平衡补偿方法

Fast Unbalance Compensation Method for Delta-connected Cascaded STATCOM Based on Sliding Mode Control

电网发生故障或者接入大功率不平衡负载时,会出现电网电压不对称,影响系统稳定运行,对其快速地进行无功补偿显得尤为重要。角型级联静止同步补偿器(Static Synchronous Compensator,STATCOM)能够对无功和负序电流进行综合补偿,是目前高压大容量应用场合最有效的电能质量解决方案之一。然而角形补偿器相电流指令信号获取方法较为复杂,指令计算速度慢,难以实现快速补偿。为此,提出一种基于滑模控制的角形级联STATCOM快速不平衡补偿方法,在根据电网电压不平衡度计算电流补偿指令时,引入滑模控制并与PI调节相结合,提升不平衡补偿指令计算速度。结合角形级联STATCOM的电压稳定控制、相间平衡控制和电流内环控制,实现电网电压的快速支撑。最后,通过仿真研究验证所提控制方法的正确性和有效性。

When the power network breaks down or connected to the high-power unbalanced load,the voltage of the power network will be asymmetric,which will affect the stable operation of the power system.So,it is particularly important to compensate the reactive power quickly.Delta-connected cascaded static synchronous compensator(STATCOM)can compensate reactive power and negative sequence current comprehensively,which is one of the most effective power quality solutions for high voltage and large capacity applications.However,the calculation method of phase current reference signals is complex and slow,as a result,the fast compensation is hard to achieved.This paper proposes a fast unbalance compensation method based on sliding mode control for delta-connected cascaded STATCOM.Sliding mode control is introduced and combined with the PI controller in the current reference loop,therefore,the references of the compensation currents can be obtained fast.Then,the response speed of unbalance compensation is improved.Combined with voltage regulation method,phase to phase balance control and current inner loop control of delta-connected cascaded STATCOM,the fast support of grid voltage is realized.Finally,the simulation results verify the correctness and effectiveness of the proposed control method.