一种可实现分布式发电系统平滑切换的三相逆变器控制方法

A Control Method for 3-Phase Inverters Enabling Smooth Transferring of the Operation Modes of Distributed Generation System

当大电网停电时,为保证关键负荷不间断供电,分布式发电系统应能从并网模式切换到孤岛模式。本文提出了一种新的分布式发电系统中三相逆变器控制方法,用于实现其运行模式的切换。与传统的混合电压电流模式控制相比,提出的控制方法除保持了较好的动态性能外,改善了切换过程中的负载电压质量。在并网模式下,逆变器控制成电流源,向电网注入给定的有功和无功电流;孤岛发生时,逆变器输出功率与关键负荷不匹配将导致电压幅度和频率发生偏移,当偏移达到给定值时,调节器自动调整电流指令使逆变器输出功率与负荷匹配,从而将电压和频率偏移限制在给定范围内,因此切换过程中的负载电压质量得到改善。同时,本文对整个系统进行了分析,并给出了参数的设计方法。最后,仿真和实验对提出的控制方法进行了验证。

Distributed generation（DG） systems should be able to transfer from grid-tied mode to islanding mode to back up critical load when utility is outage.A new control method for three phase inverter is proposed to realize transferring operation mode in DG systems.Compared to conventional hybrid voltage and current control,good dynamic performance is reserved,and load voltage quality during the transition is improved with the proposed control method.In the grid-tied mode,the inverter is controlled as a current source to inject given active and reactive current to the utility.As soon as islanding happened,the power mismatch between the inverter output and critical load demand leads the drift of voltage magnitude and frequency.And when the drift reach given value,the current reference of inverter is regulated to adjust the generated power to match the load demand.As a result,the drift can be controlled in the given range,and the load voltage quality during the transition can be improved.Besides,the whole system is analyzed and parameters are designed in the paper.Finally,the proposed control method is verified by simulation and experimental results.