一类多组交直交变频调速系统对电网谐波影响的分析

基于交流电动机拖动中的交直交变频调速系统，对电网谐波的影响问题进行了理论研究与仿真分析，提出了多组变频器的移相式组合供电方法.针对某热连轧生产线的多组辅助传动系统，分别定量分析了当输出频率变化和系统中负载对象、LC滤波器、脉宽调制电路和变压器的参数变化时，供电网侧的谐波率和波形畸变率.仿真结果表明，移相式组合供电方法及合理的拖动系统设计可以大幅度降低供电网侧谐波干扰，总谐波畸变率可抑制在4.0%以内.本研究为工厂拖动系统的设计、无功补偿系统设计以及拖动系统故障诊断提供了有效的方法. 

Harmonic analyses of power grid in a kind of multi-group AC-DC-AC variable frequency speed-regulating drive system

Based on a synchronous machine in an AC—DC—AC variable frequency speed-regulating drive system, a new power supply method of phase-shifting combination is proposed by a detailed study on the impact of power grid harmonics. With regard to the auxiliary motor drive system of a hot-rolling mill, the grid side harmonic rate and waveform distortion rate are quantitatively analyzed when the parameters of the power load, LC filter, pulse-width modulation circuit and transformer change. Simulation results show that the power supply method with the reasonable parameters3 design of the drive system can drastically reduce the grid side harmonic interference that the total harmonic distortion is suppressed within 4.0%. This study provides an effective method for the design of a factory drive system and a reactive power compensation system as well as the fault diagnosis of an electric drive system.