Math Model and Calculation Analysis of Inter-harmonic of Double PWM Speed Control System in Distribution Network

Sensors & Transducers

Li Lu-Yang¹  Li Zheng¹  Yang Wen-Huan¹  Li Rong-Gao² 

[1] School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, China ;Tongsheng Electricity Power Company Ltd., Pudong District, Shanghai, 200122, China;

关键词: Double PWM;    Switching function;    Grid-side current;    Harmonics;    Inter-harmonics.;   

DOI  :  

来源: DOAJ

【 摘 要 】

Aiming at the problem that the distribution network voltage will fluctuate because of the inter-harmonic currents injected into the network by double PWM speed control system when regulating the speed of the asynchronous motor, we established the inter-harmonic current math model of double PWM speed control system according to switching function based on a real bridge crane. The distribution law of the inter-harmonic is got by calculating the grid-side currents and their spectrum while letting the motor run at different quadrants and frequencies. The result which is verified by simulation and experiment shows that the content of the inter harmonic currents is more than that of harmonic currents in double PWM speed control system, the frequency of the inter harmonics of the grid-side current mainly focus on the scope lower than the fundamental frequency, and when the motor runs at low frequencies, the THD of the grid-side current is high. The result has verified the reason why the voltage of a bridge crane distribution system of a deepwater port in Shanghai flickers.

【 授权许可】

Unknown