柔性直流输电系统MMC换流阀闭环充电策略
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摘要
随着柔性直流输电系统的快速发展与广泛应用,其启动工况愈发具有多样性,MMC换流阀传统开环充电策略需要综合考虑系统状态变量进行参数配置,且配置难度大。由此提出了通用性的换流阀闭环充电控制策略,无需检测系统状态即能将子模块稳态电压控制在额定值,具有较好的适应性。首先,分析了柔性直流输电系统的三类充电回路及主动均压充电策略。其次,基于子模块特性不一致的均压需求分析,提出了完整的通用性闭环充电策略及对应的柔性直流输电系统的协调启动策略。最后通过PSCAD/EMTDC搭建了三端直流电网模型,仿真验证了闭环充电策略。结果表明闭合充电策略通用于各类换流站的启动充电过程,且可将子模块电压平稳充电至额定值,同时不存在桥臂过流及子模块过压等现象。
With the rapid development and wide application of the flexible DC transmission system, its starting conditions are more and more diverse. Traditional open-loop charging strategy of MMC valve requires comprehensive consideration of the system state variables for parameter configuration, and the configuration is difficult. Therefore, a general-purpose closed-loop charging strategy for the converter valve is proposed, which can control the steady state of the sub-module at a rated voltage without detecting the system state, and has a good adaptability. First of all, three kinds of charging loops and active voltage equalization charging strategies of flexible HVDC transmission systems are analyzed. Secondly, based on the analysis of equalization requirements of submodules with inconsistent characteristics, a complete universal closed-loop charging strategy and the coordination start strategy of multi-terminal flexible DC transmission system are proposed. Finally, a three-terminal DC grid model is built through PSCAD/EMTDC. Simulation results show that the closed-loop charging strategy can be generally applicable to the startup charging process of various converter stations, ensuring the submodules steadily charge to the rated voltage without bridge arm overcurrent and submodules overvoltage.
With the rapid development and wide application of the flexible DC transmission system, its starting conditions are more and more diverse. Traditional open-loop charging strategy of MMC valve requires comprehensive consideration of the system state variables for parameter configuration, and the configuration is difficult. Therefore, a general-purpose closed-loop charging strategy for the converter valve is proposed, which can control the steady state of the sub-module at a rated voltage without detecting the system state, and has a good adaptability. First of all, three kinds of charging loops and active voltage equalization charging strategies of flexible HVDC transmission systems are analyzed. Secondly, based on the analysis of equalization requirements of submodules with inconsistent characteristics, a complete universal closed-loop charging strategy and the coordination start strategy of multi-terminal flexible DC transmission system are proposed. Finally, a three-terminal DC grid model is built through PSCAD/EMTDC. Simulation results show that the closed-loop charging strategy can be generally applicable to the startup charging process of various converter stations, ensuring the submodules steadily charge to the rated voltage without bridge arm overcurrent and submodules overvoltage.
引文
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[18]肖晃庆,徐政,薛英林,等.多端柔性直流输电系统的启动控制策略[J].高电压技术,2014,40(8):2550-2557.XIAO Huangqing,XU Zheng,XUE Yinglin,et al.Start control strategy of MMC-MTDC system[J].High Voltage Engineering,2014,40(8):2550-2557.
[19]裘鹏,杨美娟,章姝俊,等.MMC-MTDC系统协调启动控制策略[J].电网技术,2015,39(7):1800-1807.QIU Peng,YANG Meijuan,ZHANG Shujun,et al.Coordinated start-up strategy for MMC-MTDC system[J].Power System Technology,2015,39(7):1800-1807.
[20]刘欣和,张浩,李道洋,等.柔性直流电网协调控制策略[J].南方电网技术,2017,11(9):1-7.LIU Xinhe,ZHANG Hao,LI Daoyang,et al.Coordinated control strategy for VSC-HVDC power grid[J].Southern Power System Technology,2017,11(9):1-7.
[2]LESNICAR A,MARQUARDT R.An innovative modular multilevel converter topology suitable for a wide power range[C]//2003 IEEE Bologna Power Tech Conference Proceedings,June 23-26,2003,Bologna,Italy:23-26.
[3]ALLEBROD S,HAMERSKI R,MARQUARDT R.New transformerless scalable modular multilevel converters for HVDC-transmission[C]//Proceedings of Power Electronics Specialists Conference,June 15-19,2008,Rhodes,Greece:174-179.
[4]YAO Zhiqing,ZHANG Qun,CHEN Peng,et al.Research on fault diagnosis for MMC-HVDC systems[J].Protection and Control of Modern Power Systems,2016,1(1):71-77.DOI:10.1186/s41601-016-0022-0.
[5]汤广福,贺之渊,滕乐天,等.电压源换流器高压直流输电技术最新研究进展[J].电网技术,2008,32(22):39-44.TANG Guangfu,HE Zhiyuan,TENG Letian,et al.New progress on HVDC technology based on voltage source converter[J].Power System Technology,2008,32(22):39-44.
[6]陈燕红,李世军,李延平,等.基于内模控制的MMC-HVDC海上风电场不对称电网下的保护策略[J].电力系统保护与控制,2018,46(22):95-103.CHEN Yanhong,LI Shijun,LI Yanping,et al.Inernal model control based protection strategy for MMC-HVDCoffshore wind farm under unbalanced grid[J].Power System Protection and Control,2018,46(22):95-103.
[7]高淑萍,胡振宇,张保会,等.一种适用于MMC-HVDC直流输电线路的保护新原理[J].电力系统保护与控制,2018,46(13):13-20.GAO Shuping,HU Zhenyu,ZHANG Baohui,et al.Anew relay protection principle of MMC-HVDCtransmission lines[J].Power System Protection and Control,2018,46(13):13-20.
[8]张磊,范彩云,韩坤,等.电网电压不对称时MMC-HVDC精确环流抑制控制[J].电力系统保护与控制,2018,46(12):42-49.ZHANG Lei,FAN Caiyun,HAN Kun,et al.MMC-HVDC precise circulation suppression control under asymmetrical network voltage[J].Power System Protection and Control,2018,46(12):42-49.
[9]刘隽,贺之渊,何维国,等.基于模块化多电平变流器的柔性直流输电技术[J].电力与能源,2011,1(1):33-38.LIU Jun,HE Zhiyuan,HE Weiguo,et al.The introduction of technology of HVDC based on modular multi-level converter[J].Power&Energy,2011,1(1):33-38.
[10]管敏渊,徐政.MMC型VSC-HVDC系统电容电压的优化平衡控制[J].中国电机工程学报,2011,31(12):9-14.GUAN Minyuan,XU Zheng.Optimized capacitor voltage balancing control for modular multilevel converter based VSC-HVDC system[J].Proceedings of the CSEE,2011,31(12):9-14.
[11]王姗姗,周孝信,汤广福,等.模块化多电平换流器HVDC直流双极短路子模块过电流分析[J].中国电机工程学报,2011,31(1):1-7.WANG Shanshan,ZHOU Xiaoxin,TANG Guangfu,et al.Analysis of submodule overcurrent caused by DCpole-to-pole fault in modular multilevel converter HVDCsystem[J].Proceedings of the CSEE,2011,31(1):1-7.
[12]孔明,邱宇峰,贺之渊,等.模块化多电平式柔性直流输电换流器的预充电控制策略[J].电网技术,2011,35(11):67-73.KONG Ming,QIU Yufeng,HE Zhiyuan,et al.Pre-charging control strategies of modular multilevel converter for VSC-HVDC[J].Power System Technology,2011,35(11):67-73.
[13]宋平岗,李云丰,王立娜,等.MMC-HVDC电容协同预充电控制策略[J].高电压技术,2014,40(8):2471-2477.SONG Pinggang,LI Yunfeng,WANG Lina,et al.Capacitor coordinating pre-charging control strategy of MMC-HVDC[J].High Voltage Engineering,2014,40(8):2471-2477.
[14]DAS A,NADEMI H,NORUMM L.A method for charging and discharging capacitors in modular multilevel converter[C]//IECON 2011-37th Annual Conference on IEEE Industrial Electronics Society,November 7-10,2011,Melbourne,Australia:1058-1062.
[15]李探,赵成勇,王朝亮,等.用于电网黑启动的MMC-HVDC系统换流站启动策略[J].电力系统自动化,2013,37(9):117-122.LI Tan,ZHAO Chengyong,WANG Chaoliang,et al.Startup schemes for converter station of MMC-HVDCsystem applied in grid black start[J].Automation of Electric Power Systems,2013,27(9):117-122.
[16]郭高朋,胡学浩,温家良,等.模块化多电平变流器的预充电控制策略[J].电网技术,2014,38(10):2624-2630.GUO Gaopeng,HU Xuehao,WEN Jialiang,et al.Precharge control strategies for modular multilevel converter[J].Power System Technology,2014,38(10):2624-2630.
[17]班明飞.模块化多电平变流器控制策略的研究[D].哈尔滨:哈尔滨工业大学,2013.BAN Mingfei.Research on control strategy of modular multilevel converter[D].Harbin:Harbin Institute of Technology,2013.
[18]肖晃庆,徐政,薛英林,等.多端柔性直流输电系统的启动控制策略[J].高电压技术,2014,40(8):2550-2557.XIAO Huangqing,XU Zheng,XUE Yinglin,et al.Start control strategy of MMC-MTDC system[J].High Voltage Engineering,2014,40(8):2550-2557.
[19]裘鹏,杨美娟,章姝俊,等.MMC-MTDC系统协调启动控制策略[J].电网技术,2015,39(7):1800-1807.QIU Peng,YANG Meijuan,ZHANG Shujun,et al.Coordinated start-up strategy for MMC-MTDC system[J].Power System Technology,2015,39(7):1800-1807.
[20]刘欣和,张浩,李道洋,等.柔性直流电网协调控制策略[J].南方电网技术,2017,11(9):1-7.LIU Xinhe,ZHANG Hao,LI Daoyang,et al.Coordinated control strategy for VSC-HVDC power grid[J].Southern Power System Technology,2017,11(9):1-7.