数字变电站IED采样的一种改进算法

An Improved Linear Lagrange Interpolation Algorithm of Sampled Values for Digital Substation IED

针对Lagrange线性插值算法在谐波次数高的情况下误差过大和Lagrange抛物线插值算法在合并单元(MU)低采样频率下误差改进不明显,提出了一种改进算法。根据改进算法的计算思路,运用Matlab7.0编程,对算法进行仿真和模拟。与线性插值算法相比,该算法大大降低了各采样点的相对误差,提高了电流、电压、功率幅值的测量精度;同时通过分析一种典型谐波信号,验证了在同样插值条件、计算量相当的情况下,加权算法在80Hz的低采样频率下,误差较二阶Lagrange算法有显著的改善,有效地抑制了谐波对算法的影响。仿真结果表明该算法计算精度高,可以满足新型变电站智能设备的采样值信号接口技术的要求。

As on the condition of high orders of harmonics, linear Lagrange interpolation algorithm has oversize errors, while the same situation, parabola Lagrange interpolation algorithm on the condition of low sampled frequency with MU. A new improved algorithm is presented in this paper. According to the characteristics of electric network signal, a weighted function is constructed. The new algorithm with weighted average between the two closed items in the Lagrange interpolation algorithm is formed. According to the calculation thought, the improved algorithm is simulated and modeled by matlab7.0. Compared with the original algorithm, the new algorithm decreases the relative errors of each sampled points greatly and improves the measured accuracy of current, voltage and power magnitudes. By analyzing a typical power harmonic signal, on the condition of high orders of harmonics, the errors of weighted algorithm is improved markedly, and the effect of algorithm with harmonics is compressed availably. The results show that the algorithm has high accuracy, which satisfies the requirement of the novel interface solution to sampled values for substation intelligent electronic device.