基于时频原子变换的电力系统同步相量测量方法

A Power System Synchronized Phasor Measurement Algorithm Based on Time-frequency Transform

时频原子变换具有理想的复带通滤波特性,对基频带滤波能够获取同步复相量并同时阻隔其他频带分量的干扰。滤波频域带宽和计算数据窗长度均实现与带通中心的频率解耦,通过尺度参数灵活控制滤波的时域和频域特性。时频原子滤波函数的实部和虚部具有一致的幅频特性,对系统频率变化有较好的适应能力。提出基于时频原子变换的同步相量测量方法,通过构造新的时频原子函数和选择最优尺度参数,能够在定间隔采样下,精确获取信号基波幅值、频率和相角,而不受信号中同时存在的大范围频偏、谐波、噪声和带外干扰的影响,且无需增加频率跟踪和滤波环节。在动态特性方面,该方法对幅值阶跃、频率阶跃和相角阶跃均具有快速响应速度,且运算量小,便于实时分析。MATLAB和EMTDC/PSCAD仿真结果均验证了所提出的方法的正确性和有效性。

Time-frequency transform（TFT） resembles an ideal complex band-pass filter.Based on this property,TFT can be used to measure the synchronous complex phasor by filtering the fundamental frequency band of the signal,without being interfered by other frequency bands.The width of frequency band and the length of data window required for the calculation are both decoupled from the centre frequency and can be flexibly controlled by the scale parameter.The real part and imaginary part of TFT have the consistent frequency-magnitude characteristics.Therefore TFT can adapt to the offset of the real system frequency.A novel algorithm for the synchronous phasor measurement based on TFT is proposed.By constructing the new time-frequency atom-function and selecting the optimal scale parameter,TFT can be used to preciously measure the fundamental magnitude,frequency and phase of the signal with the fixed interval sampling while overcoming the effects caused by the large-scale offset of frequency,harmonics,noises and out-of-band components.It is worth noting that the tracking and compensation due to frequency offset are not required in this process.Moreover,TFT has ideal dynamic characteristics with the fast response speed for the step change of magnitude,frequency and phase.Finally,the correctness and validity of the proposed algorithm are well verified by the MATLAB and EMTDC/PSCAD simulation results.