改善孤岛微电网电压波形质量的方法  

Method for Improving Voltage Waveform Quality of Islanding Microgrid

作　　者：任碧莹[1] 杨媛媛[1] 孙向东[1] REN Biying;YANG Yuanyuan;SUN Xiangdong(School of Electrical Engineering,Xi’an University of Technology,Xi’an 710048,China)

机构地区：[1]西安理工大学电气工程学院,西安710048

出　　处：《高电压技术》2023年第9期3956-3964,共9页High Voltage Engineering

基　　金：陕西省自然科学基金(2023-JC-YB-390)。

摘　　要：针对孤岛微电网公共交流母线电压对称性和波形质量易受不平衡非线性负载影响的问题,采用组合式三相逆变器作为各分布式电源的拓扑电路,并设计了提高逆变器输出电压质量的控制策略。首先,分析了不平衡非线性负载下影响微电网电压质量的原因,得出逆变器的参考电压的平衡性和系统等效阻抗的降低是提高电压质量的2大要素。然后,设计了平衡的参考电压控制使逆变器各相产生对称的参考电压;提出了自调整频率下的比例谐振电压控制器及其离散化下的系数自调整策略,同时增加输出电流前馈控制。这些方法在提高系统开环增益的同时可有效减小逆变器各次频率处的输出阻抗,改善因逆变器输出阻抗压降带来的不平衡和电压波形质量问题。最后通过仿真和实验结果验证了所提控制策略的可行性。The symmetry and waveform quality of the common AC bus voltage in an islanding microgrid are easily affected by the unbalanced and nonlinear loads.In this paper,the combined three-phase inverter is adopted as the topology of each distributed power supply,and the control strategy to improve the output voltage quality of the inverter is designed.Firstly,the reasons affecting the voltage quality of microgrid with unbalanced and nonlinear loads are analyzed.It is concluded that the balance degree of inverter reference voltage and the reduction of system equivalent impedance are the two elements to improve the voltage quality.Then,a balanced reference voltage control is designed to enable each phase of the inverter to produce symmetrical reference voltages.The proportional resonant voltage controller with self-adjusting frequency and the self-adjusting coefficient strategy under discretization is proposed.At the same time,the output current feedforward control is added.These methods can be adopted to effectively reduce the inverter output impedance at fundamental and each harmonic frequency while improving the open-loop gain,and the imbalance and voltage waveform quality caused by the output impedance voltage drop of the inverter is improved.Finally,the feasibility of the proposed control strategy is verified by simulation and experimental results.

关 键 词：微电网 组合式三相逆变器 电压质量 平衡的参考电压控制 自调整频率的多谐振控制器 

分 类 号：TM464[电气工程—电器] TM727