关于瞬时无功功率理论的探讨

通过瞬时无功功率P-Q理论(IRP)及电流物理分量理论(CPC)在电网电压、电流为正弦的三相三线制不对称电路中的应用的对比,表明瞬时无功功率理论的分析结果与电路中的某些功率现象不一致:即无功功率Q为零时,瞬时无功电流可能不为零;有功功率P为零时,瞬时有功电流不为零;电源电压为正弦,负荷为非谐波源时,瞬时有功电流和瞬时无功电流中都包含三次谐波分量。瞬时有功功率p、瞬时无功功率q与有功功率P、无功功率Q及不平衡功率D之间的关系说明p、q分别与多个功率现象相关,仅用P、Q的瞬时值不能无延时的辨识三相负荷不对称系统的功率特性。这一结论对有源电力滤波器的控制算法具有重要意义。

Discussion on Instantaneous Reactive Power P-Q Theory

The comparison of the instantaneous reactive power P-Q theory(IRP) with the theory of the current's physical components(CPC) presented in this paper reveals the results of the IRP P-Q theory are inconsistent with power phenomena in three-phase,three-wire circuits with sinusoidal voltages and currents.Namely,according to the IRP P-Q Theory the instantaneous reactive current can occur even if a load has zero reactive power Q.Similarly,the instantaneous active current can occur even if a load has zero active power P.Moreover,these two currents in circuits with a sinusoidal supply voltage can be nonsinusoidal even if there is no source of current distortion in the load.The relationship between the instantaneous powers(p,q) and the active,reactive and unbalanced power(P,Q,D) shows the p and q powers are associated with multiple phenomenon,and the IRP P-Q Theory can not identify power properties of three-phase unbalanced loads with a pair of values of p and q powers instantaneously.This conclusion may have an important value for control algorithms of active power filters.