不平衡负载下基于改进下垂控制策略的组合式三相逆变器控制  

Improved Droop Control Based Three-Phase Combined Inverters for Unbalanced Load

作　　者：任碧莹[1] 赵欣荣[1] 孙向东[1] 杨惠[1] 

机构地区：[1]西安理工大学电气工程系,陕西省西安市710048

出　　处：《电网技术》2016年第4期1163-1168,共6页Power System Technology

基　　金：国家自然科学基金项目(51477139)~~

摘　　要：低压微电网中,负载不平衡易引起逆变器三相输出电压的不对称。为改善系统输出电压的对称性,以组合式三相逆变器为研究对象,设计了系统的整体控制策略。针对传统有功-频率(P-f)下垂控制存在的系统频率越限问题,采用了sigmoid P-f下垂控制;并在此基础上,针对三相负载不平衡引起的电压不平衡问题,提出了改进sigmoid P-f/改进无功-电压(Q-U)下垂控制策略,该策略通过调整sigmoid P-f下垂曲线频率设定点及Q-U下垂曲线空载电压点来实时调节三相参考电压的幅值和频率,保证三相输出电压的对称性。仿真和实验结果验证了所提策略的有效性。In low voltage microgrid, asymmetric 3-phase inverter voltages could be caused by 3-phase unbalanced loads. In order to keep 3-phase voltages symmetric, system control strategy is designed based on 3-phase combined inverter in this paper. Sigmoid P-f droop control is adopted to settle the problem that system frequency is out of range with traditional power-frequency（P-f） droop control in certain cases. An improved droop control strategy is proposed to decrease unbalance degree in output-voltage waveform caused by 3-phase unbalanced load. In the proposed strategy, 3-phase voltage references are changed in real time through adjusting frequency setting point on sigmoid P-f droop curve and no-load voltage point on power-voltage（Q-U） droop curve to ensure symmetry of 3-phase output voltages. Feasibility and effectiveness of proposed strategy were confirmed with simulation and experiment.

关 键 词：组合式三相逆变器 下垂控制 SIGMOID函数 不平衡负载 

分 类 号：TM46[电气工程—电器]