基于多机组并联的10 kV电网有源滤波器扩容方法

随着新能源发电、电力传动为代表的电力电子装置的大规模应用,供电网络中存在有大量谐波分量及无功冲击,有源滤波器(APF)正是在上述背景下提出的。然而,受限于电力电子器件单体容量限制,单机APF无法满足10 kV输电网络大容量补偿需求。为此,提出一种基于多机并联技术的10 kV电网有源滤波器扩容方法,考虑到10 kV电网负载侧特有的中压、大电流特性,采取变流器并联技术实现APF装置容量提升。建模可知,并联APF电路模型中存在低频环流通路,从而影响并联APF控制系统电流内环运行特性,为此采取零序电压修正方式实现并联APF环流限制。最后,10 kV/1 MW工程样机对APF并联补偿技术进行可行性验证,装置投入后10 kV网侧电流总畸变率由23.4%降低为3.1%,且谐波分量均集中在两倍开关频率及其倍频段。

Capacity Expansion Method for Active Power Filters in 10 kV Grids Based on Parallel Multi-units

Along with large-scale application of power electric devices represented by new energy power generation and power transmission,there exist large amounts of harmonic components and reactive power impact in power supply networks,and there comes the active power filters (APF).However,confined by the capacity of single power electric device,single APF cannot meet the high capacity compensation demand of the 10 kV power transmission network.In this background,a capacity expansion approach for l0 kV grid APFs based on parallel multi-units was presented.In consideration of the characteristics of middle voltage and high current at the load side of the 10 kV grid,we used parallel inverter technology to achieve APF capacity expansion.Through modeling,we realized that a low-frequency circulating-current path is present in the parallel APF circuit model,affecting operational characters of the inner current loop of the parallel APF control system.To deal with this situation,we used the zero-sequence voltage correction method to realize limitation of APF loop current.Finally,we used a 10 kV/1 MW prototype to verify the feasibility of the parallel APF parallel compensation technique and concluded that the total current distortion rate at the l0 kV network side dropped from 23.4％ to 3.1％ and harmonic components were concentrated at double switching frequency and in the double frequency band.