基于全相位FFT改进相位差法的自动准同期并列参数测量

Generator quasi synchronization parameter measurement method based on improved phase difference method of all-phase fast Flourier transform

发电机准同期并列的关键在于对并列双方电压参数的快速准确测量。但由于并列双方电压频率不同,很难同时对双方电压做到同步采样,传统的基于快速傅里叶变换(Fast Flourier Transform,FFT)的准同期并列参数测量结果因频谱泄露产生较大误差。为抑制泄露,提高参数测量精度,引入了全相位频谱分析技术,并分析了全相位FFT与常规卷积窗FFT的区别与联系。在此基础上提出了基于全相位FFT的发电机准同期参数测量方法,并对全相位FFT相位差法进行了改进,提出了简洁的基波频率及幅值计算方法,使其更好地满足准同期并列的需要。通过仿真计算验证了所提方法性能优良,能有效克服频率波动、谐波、噪声及电压非稳态变化等不同情况的影响,实现并列双方电压参数的快速准确测量。

It is the key task for automatic quasi synchronization parallel operation to estimate the parameters of both generator voltage and power system voltage rapidly and precisely. However, due to the difference between the two voltage frequencies, it is difficult to perform the synchronous sampling of the two voltage signals simultaneously, so when measuring the parameter based on fast Flourier transform （FFT for short）, the measurement result will have a great error because of spectrum leakage. To restrain the spectrum leakage and improve the accuracy, the technology of all-phase spectrum analysis is introduced. The difference and connection between all-phase FFT （apFFT for short） and traditional convolution-window FFT is analyzed and the advantage of apFFT is pointed out. Based on it, the generator quasi synchronization parameter measurement method based on double-window apFFT is presented. To meet the needs of quasi synchronization parameter measurement better, the common apFFT phase-difference spectrum correction method is improved and a concise calculation method for fundamental frequency and amplitude is proposed. Simulation verify the excellent performance of the proposed method, which can overcome the impact of frequency fluctuation, harmonic, noise, non-stationary change and realize rapid and accurate parameter measurement of the two voltage signals of quasi synchronization.