基于费马点的三相三线制功率振荡抑制策略

Power Oscillation Cancellation Strategy for Three-phase Three-wire Grid-connected Inverter Based on Fermat Point Theory

针对三相三线制并网逆变器功率振荡抑制传统方法运算复杂、物理意义不显著的局限性,本文提出一种基于费马点的三相三线制并网逆变器新型功率振荡抑制方法.通过定义故障系统线电压三角形等角中心(费马点)为"新中性点",可将三相静止坐标系下的电压幅值跌落、相角偏移的不对称故障转化成费马点坐标系下的电压幅值故障.根据数学推导功率分配与系统功率振荡的规律,设计一种新型功率振荡抑制策略,摆脱了传统方法dq变换的控制体系,探索了一种解决功率振荡抑制问题的新思路,且具有良好的功率振荡抑制效果.

Considering that the traditional power oscillation cancellation method for a three-phase three-wire grid-con⁃nected inverter has limitations of complicated operation and insignificant physical meaning,a novel power oscillation cancellation method based on Fermat point theory is proposed in this paper.By defining the triangle equiangular center(i.e.,Fermat point)of the system’s fault line voltage as the“new neutral point”,the asymmetric faults such as voltage magnitude sag and phase angle shift in a three-phase stationary coordinate system can be converted into voltage magni⁃tude fault under the Fermat-point coordinate system.In addition,by deriving the law of power distribution and system power oscillations mathematically,a novel power oscillation cancellation strategy is designed,thereby avoiding the con⁃trol system of the traditional dq coordinate transformation and providing a new idea to solve the problem of power oscilla⁃tion cancellation with satisfying effect.