三相电压不对称时广义谐波电流的一种新的检测方法

利用瞬时无功功率理论进行三相电压不对称谐波电流检测时会出现较大的误差,对此将扇合矢量表示法推广应用于三相不对称系统。提出了一种新的扇合变换向量,使三相系统归一化为单相系统,从而简化了三相系统基波有功分量的提取,即使在电网电压不对称时仍能准确有效检测出谐波电流。接着提出并证明了DFT的基相量循环移位性质,根据该性质得到了从三相电流扇合矢量中提取基波有功分量的递推算法,大大减少了计算量,提高了检测实时性。仿真分析对该方法的正确性和可行性进行了证明。

A new detecting method for generalized harmonics currents in the case of unsymmetrical three-phase valtages system

Harmonic currents can be detected exactly by theory of instantaneous reactive power in three-phase symmetry power systems,but with large errors in unsymmetrical three-phase system.The method of fan-in vector expression is expanded to use in an unsymmetrical three-phase system.A new fan-in transfer vector is proposed.It transfers a three-phase system into a single-phase system.So it simplifies the detecting mothod for getting active component from a three-phase system.In addition,the cyclic shift character of base-phase in DFT is proposed and approved in this paper.A step-by-step algorithm is achieved for getting active currents component from the fan-in vector of three-phase currents accending to the character.It not only greatly reduces the calculation quantities but also makes a better real-time detection.Simulations are carried out to verify the feasibilily and correctness of the method.