Hilbert transform is widely used in the measurement of reactive power in power systems. Traditional method used to perform Hilbert transform is based on DFT and IDFT algorithm. This method meets with problems of needing too much computation time, poor real-time quality and further improving the measurement precision. A new method for Hilbert transform based on window-added FFT and IFFT is proposed in this paper. First, window functions are added to the original signals then the signal is accumulated into one period and FFT is used to get the harmonic parameters; Finally, IFFT is performed with the processed parameters and the results are extended periodically to get the 90-degree phase-shifted final signal. Compared with the traditional method, the new method has reduced the calculation time and reached the higher precision. Theoretical derivation demonstrates that for a signal sampled 64 points per period, the new method can save about 63 percent of the calculating time. The rapidity and accuracy of the new method is further demonstrated in the results of engineering practice.%电力系统无功功率测量中,Hilbert变换方法应用较为广泛.传统的基于DFT和IDFT的Hilbert变换法计算时间长,实时性差且精度有待进一步提高.文中提出一种基于加窗FFT和IFFT的Hilbert变换新方法,具体实现过程为:对原始信号加窗;将加窗信号累加到一个周期并进行FFT运算,得到信号各次谐波参数;对处理后的谐波参数进行IFFT运算并将结果周期延拓,实现信号的90°相移.相对于传统方法,新方法计算量小且精度更高.理论推导表明,对于单周期采样64点的信号,改进算法节省时间量约为63%.将改进算法应用于工程实践,结果进一步验证了其快速性和准确性.
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