基于改进DFT的电力系统同步相量测量算法研究

离散傅里叶变换(DFT)在相同条件下,具有运算效率高、易于嵌入等优点,被广泛应用于电力系统同步相量测量中。但由于非同步采样及频域离散化问题的存在,DFT在进行相量测量时会出现频谱泄露和栅栏效应,使得计算结果产生误差。针对这一问题,推导了DFT在非同步采样情况的相角误差方程,利用相角差对信号频率进行跟踪测量,得到精度较高的频率值。据此,提出了基于改进DFT的同步相量测量方法,利用跟踪所得频率将DFT结果分为整数部分和分数部分,并通过等效替换对分数部分进行了修正。经仿真实验证明,该方法具备较高的抗干扰能力和测量精度,整体效果较传统算法有了很大的提升。在此基础上,利用TMS320F2812设计了一个同步相量测量装置(PMU)硬件系统,通过该系统实现了频率、幅值和相角的准确测量。

Research on Synchronous Phasor Measurement Algorithm of Power System Based on Improved DFT

Discrete Fourier transform has many advantages,such as easy for embedding,high efficiency,and etc,so it is widely used in synchronized phasor measurement in power system.However,due to the existence of non-synchronous sampling and frequency domain discretization,the spectrum leakage and fence which cause the errors of calculation result will occur when the DFT is used in phase measurement.To solve this problem,in this paper the equations of phase angle error are deduced in the non-synchronous sampling,then the difference of phase angles is utilized to track the frequency of power measurement signal.Accordingly a method of synchronized phasor measurement based on improved DFT algorithm is proposed.The calculation results of improved DFT algorithm are divided into an integer part and a fractional part,and the fractional part is modified by the equivalent replacement.The simulation results show that the method has higher accuracy and anti-jamming capability,and the performance has greatly improvement compared with the traditional algorithm.On this basis,a phasor measurements unit hardware system is designed by using TMS320F2812.Utilizing it,accurate measurement results of frequency,amplitude and phase angle are obtained.