基于改进线性二次调节器的微电网运行模式无缝切换控制策略  

Seamless switching control strategy for microgrid operation mode based on an improved linear secondary regulator

作　　者：孙佳航 黄景光[1] 徐慧鑫 陈勇 张霞 王楷杰 SUN Jiahang;HUANG Jingguang;XU Huixin;CHEN Yong;ZHANG Xia;WANG Kaijie(College of Electrical Engineering and New Energy,China Three Gorges University,Yichang 443002,China;State Key Laboratory of Advanced Electromagnetic Engineering and Technology(Huazhong University of Science and Technology),Wuhan 430074,China)

机构地区：[1]三峡大学电气与新能源学院,湖北宜昌443002 [2]强电磁工程与新技术国家重点实验室(华中科技大学),湖北武汉430074

出　　处：《电力系统保护与控制》2023年第22期120-132,共13页Power System Protection and Control

基　　金：国家自然科学基金项目资助(52107095)。

摘　　要：微电网的主要特点之一是能够在并网模式和孤岛模式下运行,进行微电网运行模式之间的切换可能导致电压和频率的显著波动,严重时会威胁到整个系统的稳定性。无缝切换控制策略是保证微电网稳定可靠运行的关键,为解决传统无缝切换控制策略易受干扰影响和动态稳定性差的问题,提出了一种基于改进线性二次调节器的微电网运行模式无缝切换控制策略,该策略包括并网-孤岛平滑调节器和孤岛-并网平滑调节器。并网-孤岛平滑调节器通过对传统电压控制环的改进,可以为系统提供更多的阻尼并补偿逆变器输出处的瞬态电压降,从而改善系统动态性能。同时,通过对传统下垂控制策略的改进,可以根据系统有功功率的变化来调整其下垂系数,在受干扰的情况下能够将频率偏差降低到期望的水平。孤岛-并网平滑调节器考虑内部控制回路和PLL动态的情况下,根据并网控制策略下的状态空间模型对传统电流控制回路进行了改进,可以保证PCC两侧电压的同步性和微电网频率的稳定性。最后,对所提出的控制策略进行了小信号分析,同时研究了孤岛检测算法对控制策略的潜在影响,突出了所提策略的鲁棒性,并验证了所提控制策略能够平滑稳定地实现微电网运行模式间的切换。One of the main features of microgrids is their ability to operate in both grid-connected and islanded modes.Switching between microgrid operating modes can lead to significant voltage and frequency fluctuations,which can seriously threaten the stability of the entire system.Seamless switching control strategy is the key to ensuring stable and reliable operation of a microgrid.To solve the problems that traditional seamless switching control strategy is susceptible to interference and poor dynamic stability,a strategy based on an improved linear secondary regulator is proposed,one which includes grid-islanding and islanding-griding smoothing regulators.The grid-islanding smoothing regulator improves the system dynamic performance by providing more damping and compensating for transient voltage drops at the inverter output through an improvement to the traditional voltage control loop.Also,by improving on the traditional sag control strategy,it can adjust its sag coefficient according to changes in the active power of the system and is able to reduce the frequency deviation to the desired level in the presence of disturbances.The islanding-grid smoothing regulator considers the internal control loop and PLL dynamics and improves the traditional current control loop according to the state space model under the grid-connected control strategy.This can ensure the synchronisation of the voltages on both sides of the PCC and the stability of the microgrid frequency.Finally,a small-signal analysis of the proposed control strategy is carried out,and the potential impact of the islanding detection algorithm on the control strategy is investigated,highlighting the robustness of the proposed strategy and verifying that the proposed control strategy can achieve smooth and stable switching between microgrid operation modes.

关 键 词：并网模式 孤岛模式 微电网 线性二次调节器 平滑过渡 

分 类 号：TM73[电气工程—电力系统及自动化]