张金平,李建立,段晨.计及负频率影响的新能源发电低频间谐波检测方法[J].电测与仪表,2020,57(2):95-100. zhang jinping,li jianli,duanchen.Low frequency interharmonic detection method for new energy generation considering negative frequency contribution[J].Electrical Measurement & Instrumentation,2020,57(2):95-100.
Low frequency interharmonic detection method for new energy generation considering negative frequency contribution
In recent years, with the rapid development of new energy, more and more power electronic devices are applied in the power grid, resulting in the occurrence of sub-synchronous interharmonics in power signals. Influenced by the negative frequency components, the existing discrete spectrum correction methods have large errors in estimating the parameters of this kind of low frequency interharmonic signals. In order to improve the accuracy of spectrum analysis, a discrete spectrum correction method with negative frequency effect is proposed based on the specified signal processing recommendations by IEC61000-4-7. Firstly, the discrete spectrum correction model including negative frequency is established according to the spectrum characteristics of the signal after DFT. Secondly, according to the periodicity of the discrete spectrum, spectrum equations is constructed by using four spectral lines closing to the local peak value to solve the frequency correction component of the low frequency interharmonic. Then, based on the estimated frequency, the spectrum value and conjugate value of the interharmonic peak line are used to correct the amplitude and phase parameters. The simulation results show that the method proposed in this paper can effectively reduce the influence of negative frequency components on spectral line interference of signals, improve the frequency, amplitude and phase correction accuracy of low frequency interharmonics, and have good anti-noise performance.