基于FBD法的基波正负序电流实时检测方法

为了快速、有效地检测电气化铁道供电系统中的基波正、负序电流和高次谐波电流,文中提出了一种基于FBD(Fryze-Buchholz-Dpenbrock)法的电流实时检测方法。利用锁相环跟踪三相不对称或畸变电压的某一相,获取其频率和相位信息,以此构造基波正序参考电压和基波负序参考电压;利用构造的正、负序参考电压和检测出的三相电流求得对应的正、负序等效电导;对电导进行低通滤波器滤波,获取其正、负序直流分量;将电导的正、负序直流分量乘以相应的正、负序参考电压,即可获得基波正、负序电流;从总电流中减去基波正、负序电流即得到谐波电流。由于该方法只需要检测系统三相电压中一相的基波频率和相位,因此可应用于系统电压不对称或畸变的情况。该方法无需Park变换和dq变换,计算量较小。仿真结果证实了该方法的正确性和有效性。

A Real-time Method for Detecting Fundamental Positive and Negative Sequence Currents Based on FBD

In order to detect the fundamental positive and negative sequence currents and harmonic currents effectively and efficiently in electrified railway power systems,a new detecting method based on Fryze-Buchholz-Dpenbrock(FBD) method is proposed.In order to construct the fundamental positive and negative sequence reference voltages,phase locking loop(PLL) is used to track a phase of asymmetrical three-phase or distortion voltage to obtain frequency and phase information.Using constructed positive and negative sequence reference voltages and detected three-phase currents,it can obtain the corresponding positive and negative sequence equivalent conductances.After filtering the conductances with low-pass filter(LPF),positive and negative sequence DC components can be obtained.Fundamental positive and negative sequence currents can then be calculated by multiplying the positive and negative DC components with the corresponding positive and negative sequence reference voltages.Harmonic currents can be obtained by subtracting the fundamental positive and negative sequence currents from the total currents.Because this method only requires detecting one fundamental frequency and phase of system three-phase voltages,it can be used under asymmetrical or distorted system voltages.This method does not require Park and dq transformations and the computational cost is very low.The simulation results confirm the accuracy and validity of the method.