基于大型光伏直流升压汇集系统的限流控制研究  

Research on Current Limiting Strategy Based on Large-Scale Photovoltaic DC Boost Collection System

作　　者：李猛 陈想 和敬涵[1] 闫诗琪 LI Meng;CHEN Xiang;HE Jinghan;YAN Shiqi(School of Electrical Engineering,Beijing Jiaotong University,Beijing 100044,China)

机构地区：[1]北京交通大学电气工程学院,北京100044

出　　处：《内蒙古电力技术》2024年第4期23-31,共9页Inner Mongolia Electric Power

基　　金：国家自然科学基金面上项目“海上风电柔性低频输电线路保护原理研究”(52377070)。

摘　　要：针对大型光伏直流并网汇集系统双极故障后短路电流上升快、幅值高,在系统中附加限流设备或改进换流器拓扑限制直流短路电流,又会额外增加建设成本的问题,提出一种模块化多电平换流器(Modular Multilevel Converter,MMC)两阶段限流控制,首阶段保障限流控制快速性,次阶段增加MMC限流程度,同时结合光伏直流汇集系统结构提出相应的控制和保护协调方案。首先分析了短路电流影响因素,进一步提出两阶段限流控制实现方法,探讨了限流控制对系统影响并给出系统的限流控制与保护系统协调流程,最后在±30 kV/30 MW的光伏直流并网汇集系统中对限流控制进行仿真验证。仿真结果表明,所提两级式限流控制能迅速投入并显著降低故障电流及桥臂电流,控制直流断路器设计成本,降低换流器闭锁风险。In response to the problem of rapid rise and high amplitude of short-circuit current after bipolar faults in largescale PV DC grid-connected pooling systems,and additional cost of adding current-limiting equipment or improved converter topology to limit the DC short-circuit current in the system,this paper proposes a modular multilevel converter(MMC)with a two-stage current-limiting control.The author proposes a two-stage current limiting control strategy of modular multilevel converter.The first stage guarantees the speed of current limiting control,and the second stage increases the degree of MMC current limiting.At the same time,the corresponding control and protection coordination schemes are proposed based on the structure of the photovoltaic DC collection system.Firstly,the influencing factors of short-circuit current are analyzed,and then a two-stage current-limiting control method is proposed to explore the influence of current-limiting control on the system and the coordinated process between current-limiting control and protection system is provided.Finally,the current-limiting control is simulated and verified in a±30 kV/30 MW PV DC grid-connected collection system.The simulation results show that the proposed two-stage current-limiting control can be quickly put into operation and significantly reduce the fault current and bridge arm current,control the design cost of DCCB,and reduce the risk of converter blocking.

关 键 词：半桥型MMC 新能源直流并网 故障电流抑制 主动控制 光伏系统 

分 类 号：TM615.2[电气工程—电力系统及自动化]