A Method of Discriminating Nonlinear Load Current State Based on Dynamic Iterative Step Size

Abstract

The invention discloses a nonlinear load current state discrimination algorithm based on a dynamic iterative step length, and belongs to the technical field of electric power. Firstly, a direct computing method and a simple iterative algorithm for computing the average value of load current according to Fourier series indication of the nonlinear load current, and the optimal iterative algorithm is obtained based on the simple iterative algorithm. Secondly, a nonlinear load current state discrimination algorithm based on the optimal iterative algorithm is obtained according to the load current state discrimination idea provided by the optimal iterative algorithm. Finally, the dynamic iterative step length is introduced into the nonlinear load current state discrimination algorithm based on the optimal iterative algorithm, so that the nonlinear load current state discrimination algorithm based on the dynamic iterative step length is obtained. The nonlinear load current state discrimination algorithm can accurately discriminate the state of the load current, and is only related to the load current but not related to power voltage (reference signals).

Description

technical field [0001] The invention belongs to the technical field of electric power, and more precisely relates to a method for discriminating the nonlinear load current state of a power system. Background technique [0002] With the widespread use of power electronic equipment in power systems, power harmonic pollution is becoming more and more serious. Active power filter is a new type of power electronic device that controls harmonics and compensates reactive power, and harmonic current detection is the key technology of active power filter. [0003] In 1983, Japanese scholar Akagi et al. put forward the famous theory of instantaneous reactive power of three-phase circuit. Since then, this theory has been continuously improved. Now, the three-phase active power filter harmonic current detection method based on the instantaneous reactive power theory of the three-phase circuit is a relatively mature method that has been recognized. However, this type of method requires...

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Problems solved by technology

[0005] In 2006, domestic Li Zicheng et al. proposed a non-linear load current state algorithm (see LiZ, SunY. Anew compensation current real-time computing method for poweractive filter based on double linear construction algorithm [J]. Science in China Series E: Technological Sciences, 2006, 49 (4): 485-512.), but the algorithm Complicated and misjudged

In 2008, Li Zicheng and others improved the above algorithm. Although the improved algorithm does not have misjudgment, it is still relatively complicated (see Li Zicheng, Sun Yukun, Liu Guohai, etc. An improved algorithm for judging the load current state[J]. High voltage technology ,2008,34(10):2221-2227.)

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