Study On Synthetic Performance Of Algorithms For Microprocessor-Based Protections

Algorithms for microprocessor-based protections are very important in the research on the microprocessor-based protections, for all kinds of functions of protections were achieved mainly by algorithms. To select appropriate algorithms is one of the basic issues of microprocessor-based protections.The algorithms should be precise enough to satisfy the requirements of the definite engineering and the time they consume should be as less as possible. When we select algorithms, we should consider two issues—speed and precision. But the speed is contrary with the precision. In order to acquire higher precision, we will use more sampling hits, which will consume more time and reduce the rate.To study the algorithms for microprocessor-based protections will be useful for us to select an appropriate one and make it improved and compensated in certain situation. It will do a favor to improve the selectivity, quick-acting, reliability and sensitivity in protections and satisfy the requirements of the electric network operating safely and stably. The study has some certain value of guidance for its application in actual engineering.This paper presents four sorts of algorithms which are separately based on sinusoidal function model, periodic function model, random function model and simplified transmission line model and analyzes the error source, frequency response, filtering performance and applicable situation of them. In order to find a best combining algorithm from Fourier algorithm, recursive least square algorithm, and Kalman filter algorithm for elimination of decaying aperiodic component, a lot of simulation calculations are carried out, and the calculation speed of diversified algorithms and the accuracy of the results are compared. This paper also presents several sorts of improved methods based on Fourier algorithm which are used in microprocessor-based protections in recent years and compares these improved algorithms in the respect of filtering decaying aperiodic component, which provides guidance in searching a fit algorithm in certain situation. This paper gives an improved shunt compensation algorithm withoutinfluence of decaying DC component, which is proved good enough to meet the need of both accuracy and speed by the results of simulating calculation. In order to compare and analyse the performance of anti-jamming of Fourier algorithm, recursive least square algorithm, and Kalman filter algorithm, a lot of simulation calculations are carried out under the condition of burr or un-integrate wave.