基于改进DFT信号重构的基波正序有功和无功电流检测

为了满足复杂工况下基波正序有功、无功电流精确检测的需要,提出一种基于参考相位的改进型DFT算法,实现αβ轴系下基波电压、电流及其正交量的重构。结合瞬时对称分量变换和瞬时无功功率理论进一步提取基波正序有功、无功电流。考虑电网频率波动问题,利用等角度间隔采样原理在线跟踪电网频率变化。相比于常规的dq法,该方法省略了锁相环和低通滤波器,可准确、实时地求出基波正序电流的有功和无功分量。最后通过仿真和实验验证了该方法的正确性和可行性。

Detection method of fundamental positive active and reactive current based on signal reconstruction with improved DFT

An improved DFT algorithm based on reference phase is presented for purpose of accurate de-tection of positive fundamental active and reactive currents under complicated conditions.Using this algo-rithm mentioned,the fundamental voltage and current and the corresponding orthogonal component can be reconstructed under the αβ reference frame.Then the fundamental positive sequence active and reactive current were extracted by the instantaneous symmetrical component method and the instantaneous reactive power theory. Considering frequency fluctuation of power grid,the frequency variation was tracked online with equal-angle interval sampling principle.Compared with the conventional dq transformation detection method,this method is on αβ reference frame and without the phase-locked loopand low pass filter, and the active component of fundamental positive-sequence current can be obtained exactly and quickly. At last,the efficiency and feasibility of the method is proved by simulation and experimentation.