一种三相级联H桥光伏并网系统参与电网频率支撑的控制策略  

Grid Frequency Support Control Strategy of Three-phase Cascaded H-bridge Photovoltaic Grid-connected System

作　　者：李学庆 原熙博[2] 柴建云[3] 黎明[4] 李梁冉 由蕤 LI Xueqing;YUAN Xibo;CHAI Jianyun;LI Ming;LI Liangran;YOU Rui(College of Electrical Engineering,Qingdao University,Qingdao 266071,Shandong Province,China;School of Electrical Engineering,China University of Mining and Technology,Xuzhou 221116,Jiangsu Province,China;Department of Electrical Engineering,Tsinghua University,Haidian District,Beijing 100084,China;College of Engineering,Ocean University of China,Qingdao 266100,Shandong Province,China)

机构地区：[1]青岛大学电气工程学院,山东省青岛市266071 [2]中国矿业大学电气工程学院,江苏省徐州市221116 [3]清华大学电机工程与应用电子技术系,北京市海淀区100084 [4]中国海洋大学工程学院,山东省青岛市266100

出　　处：《电网技术》2023年第4期1407-1414,共8页Power System Technology

基　　金：山东省重点研发计划项目(重大科技创新工程)(2019JZZY010902);山东省自然科学基金项目(ZR2020ME197);国家自然科学基金项目(51761135014)。

摘　　要：光伏发电具有清洁、安全等特点,是解决能源危机和环境污染的有效途径。然而,光伏并网逆变器不具有转动惯量和阻尼,随着光伏发电在电网中的渗透率不断提高,大规模光伏并网对电网的频率稳定提出了挑战。级联H桥逆变器因具有模块化结构、无需工频变压器等优点,在光伏发电领域具有广阔的应用前景。针对三相级联H桥光伏并网系统,提出了一种具有支撑电网频率功能的逆变器控制策略,利用各光伏组串的有功功率储备,在不增加储能装置的情况下,实现了对电网频率动态特性的改善。针对级联H桥拓扑常见的相间功率不平衡问题,利用提出的储备功率在各相间和相内各模块间的分配方法,可实现对各光伏组串输出功率的平衡控制,最大限度保证了相间和相内各模块间的功率平衡,从而保证了系统三相电流的平衡输出,并降低了H桥模块过调制的风险。最后,在Matlab/Simulink中搭建了仿真模型和10kW模拟实验平台,通过仿真和实验对提出的控制策略的有效性进行了验证。As a clean and safe energy resource,photovoltaic(PV)power generation has become an effective way to solve the problems like energy crisis and environmental pollution.However,because the PV grid-connected inverter does not have inertia and damping characteristics,with the increased penetration of PV power generation in the grid,the large-scale PV grid-connection has posed a challenge to the grid frequency stability.The cascaded H-bridge(CHB)inverter has become a promising candidate for the PV systems due to its advantages of having a modular structure and being able to directly connected to the grid without any power frequency transformers.An inverter control strategy with the function of supporting the grid frequency is proposed in this paper for the three-phase CHB PV grid-connected system.With the PV string active power reserve,the grid frequency dynamic characteristics are improved without any extra energy storage devices.In order to avoid the common three-phase power imbalance for the CHB topology,the power reserve distribution control is used in between the three phases and between the PV strings in each phase.Therefore,the three-phase power balance and the H-bridge input power balance are maximized,the balanced three-phase current output is realized,and the over-modulation risk in the H-bridge module is reduced.Finally,simulation models are built in the Matlab/Simulink and a 10kW experimental platform is also built,verifying the effectiveness of the control strategy proposed.

关 键 词：光伏发电 级联H桥逆变器 频率支撑 有功功率储备 

分 类 号：TM721[电气工程—电力系统及自动化]