Research On Power Quality Detection Algorithm For Digital Substation

With the substation continuous development of digital and intelligent, quality monitoring equipment function and structure will be a huge change in new environment, and this also had an impact to detection algorithm for power quality. To solve these problems brought by changes, this article was studied and improved algorithm in three aspects:the harmonic fast algorithm, frequency detection algorithm and the voltage and current RMS detection method.Digital Substation change the way of the sampling, and a 10-cycle time interval will contain 2000 data points, as the number of points does not meet the requirements of a power of 2, so It's can not use the FFT algorithm to analyze harmonic as usual. In order to solve this problem, this paper discussed features of the Discrete Fourier transform, interpolation, hybrid-based algorithms, prime factor algorithm, Winograd FFT algorithm and the real sequence characteristics, and then put forward a algorithm of harmonic detection based on these algorithms which can fast calculation of the combination of 2000 FFT sampling points.In order to improve the code efficiency of combination FFT algorithm base on the C6000 series DSP, this paper established an accuracy verification simulation platform, then compared the accuracy results of floating-point data representation and fixed-point data representation under the combination FFT algorithm, and put forward a mixed sub-step FFT data representation method that can guarantee the accuracy of the combination FFT algorithm implemented on the premise of the efficient operation. Then this make use of external, line, and code optimization methods applied to combination FFT algorithms to calculate the speed has increased significantly.This paper analyzed the frequency measurement algorithm and found the problems of the phase error accuracy in digital substation can be resolved by increasing the window length. The simulation proved that the method can effectively improve the frequency offset accuracy of test results. For the voltage and current RMS detection algorithm, this paper has modified the RMS compensation algorithm, and correction of the fractional parton with the interpolation methodthe.The method can decreases the RMS error, and ensure the stability of the results accuracy.