一种基于导数的实时频率跟踪算法

频率是电力系统监控和保护中的重要参数,为对其进行快速准确的测量,提出了一种实时的频率跟踪算法。利用交流信号的正弦特性,通过二阶求导并进行线性化近似处理,进而事后误差补偿。算法在二阶导数初始计算时,运用Lagrange多项式进行曲线拟合。为减小多项式拟合和线性近似带来的误差,引入了误差补偿量和误差修正因子,提高了算法的计算精度。同时,分析了拟合多项式的误差余项,从而应用等比定理并在半周期长度的数据窗内进行平滑滤波,在兼顾实时性的基础上提高了算法的鲁棒性。Matlab平台上的仿真结果表明:该算法计算精度较高,对二次谐波有一定抑制作用,能较好地满足电力系统实时频率跟踪的要求。

Instantaneous frequency tracking algorithm based on derivative

Frequency is an important parameter for power system operation and protection.A frequency tracking algorithm is presented for its fast and accurate measurement,which combines second derivative with linear approximation based on the sinusoidal characteristics of AC signal and supplements posteriori error processing.Lagrange Polynomial-Fitting technique is used to calculate the second derivative.An error compensation rate and a modifying factor are introduced to increase algorithm accuracy.The remainder of fitting polynomial is analyzed and the samples acquired in a half cycle data window are filtered by equal ratios theorem to enhance the robustness as well as the real time performance.Matlab simulation results show that the algorithm is suitable for instantaneous power system frequency tracking with higher accuracy and a certain suppression of second harmonic.