柔性多状态开关改进型下垂控制策略
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摘要
柔性多状态开关(soft open point,SOP)作为可在配电网中替代传统联络开关的新型柔性一次设备,已成为主动配电网领域的研究热点。针对基于模块化多电平变流器(modularmultilevelconverter,MMC)的SOP装置,提出了一种改进型下垂控制策略,将具有功率分配特性的可调下垂系数与基于虚拟惯量的惯性下垂系数相结合。该控制策略可以根据换流站输出功率的变化相应地改变可调下垂系数以改善各端换流站的功率分配能力,提高系统稳定性。此外,该改进型下垂控制策略通过直流电容动态方程将系统频率与直流电压进行耦合,通过快速调整下垂系数调节各端MMC的输出功率,实现对弱交流电网的频率支撑,提高系统可靠性。最后,基于PSCAD/EMTDC仿真软件搭建了四端SOP系统模型,验证了所提控制策略的正确性与有效性。
Soft open point(SOP) is a new type of flexible primary equipment, able to replace normal open point in some key nodes of distribution network. Relying on the ability of controlling power flow, SOP becomes a research focus in the field of active distribution network(ADN). In this paper, an improved droop control strategy is proposed for multi-terminal SOP based on modular multilevel converter(MMC). The control strategy includes two kinds of droop coefficients. Droop coefficient can adjust active power of MMC and support grid frequency. According to the value of active power variation, the strategy can adjust the droop coefficient to allocate MMC power flexibly and maintain stability of distribution network. In addition, the improved droop control makes grid frequency coupled with DC voltage through dynamic equation of capacitance. When disturbance brings about frequency deviation, droop coefficient is adjusted to change the MMC power to support grid frequency. Finally, a four-terminal SOP system is designed based on PSCAD/EMTDC software, proving correctness and effectiveness of the proposed control strategy through three cases.
Soft open point(SOP) is a new type of flexible primary equipment, able to replace normal open point in some key nodes of distribution network. Relying on the ability of controlling power flow, SOP becomes a research focus in the field of active distribution network(ADN). In this paper, an improved droop control strategy is proposed for multi-terminal SOP based on modular multilevel converter(MMC). The control strategy includes two kinds of droop coefficients. Droop coefficient can adjust active power of MMC and support grid frequency. According to the value of active power variation, the strategy can adjust the droop coefficient to allocate MMC power flexibly and maintain stability of distribution network. In addition, the improved droop control makes grid frequency coupled with DC voltage through dynamic equation of capacitance. When disturbance brings about frequency deviation, droop coefficient is adjusted to change the MMC power to support grid frequency. Finally, a four-terminal SOP system is designed based on PSCAD/EMTDC software, proving correctness and effectiveness of the proposed control strategy through three cases.
引文
[1]邢海军,程浩忠,张沈习,等.主动配电网规划研究综述[J].电网技术,2015,39(10):2705-2711.Xing Haijun,Cheng Haozhong,Shen Zhangxi,et al.Review of active distribution network planning[J].Power System Technology,2015,39(10):2705-2711(in Chinese).
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[5]杨欢,蔡云旖,屈子森,等.配电网柔性开关设备关键技术及其发展趋势[J].电力系统自动化,2018,42(7):153-165.Yang Huan,Cai Yunyi,Qu Zisen,et al.Research on key techniques and development trend of soft open points for distribution network[J].Automation of Electric Power Systems,2018,42(7):153-165(in Chinese).
[6]王天昊,李鹏,于浩,等.变结构条件下智能配电软开关暂态快速仿真方法[J].电网技术,2018,42(7):2279-2285.Wang Tianhao,Li Peng,Yu Hao,et al.A fast algorithm of electromagnetic transient simulation for soft open points with variable structure conditions[J].Power System Technology,2018,42(7):2279-2285(in Chinese).
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[8]Gemmell B,Retzmann J D.Prospects of multilevel VSC technologies for power transmission[C]//IEEE PES Transmission and Distribution Conference and Exposition.Chicago,2008:1-16.
[9]杨晓峰,郑琼林,薛尧,等.模块化多电平换流器的拓扑和工业应用综述[J].电网技术,2016,40(1):1-10.Yang Xiaofeng,Zheng Qionglin,Xue Xiao,et al.Review on topology and industry applications of modular multilevel converter[J].Power System Technology,2016,40(1):1-10(in Chinese).
[10]周诗嘉,林卫星,姚良忠,等.两电平VSC与MMC通用型平均值仿真模型[J].电力系统自动化,2015,39(12):138-145.Zhou Shijia,Lin Weixing,Yao Liangzhong,et al.Generic averaged value models for two-level VSC and MMC[J].Automation of Electric Power Systems,2015,39(12):138-145(in Chinese).
[11]刘盼盼,荆龙,吴学智,等.一种MMC-MTDC系统新型协调控制策略[J].电网技术,2016,40(1):64-69.Liu Panpan,Jing Long,Wu Xuezhi,et al.A new coordinated control strategy for MMC-MTDC system and stability analysis[J].Power System Technology,2016,40(1):64-69(in Chinese).
[12]唐庚,徐政,刘昇,等.适用于多端柔性直流输电系统的新型直流电压控制策略[J].电力系统自动化,2013,37(15):125-132.Tang Geng,Xu Zheng,Liu Sheng,et al.A novel DC voltage control strategy for VSC MTDC systems[J].Automation of Electric Power Systems,2013,37(15):125-132(in Chinese).
[13]孙黎霞,陈宇,宋洪刚,等.适用于VSC-MTDC的改进直流电压下垂控制策略[J].电网技术,2016,40(4):1037-1043.Sun Lixia,Chen Yu,Song Hongang,et al.Improved voltage droop control strategy for VSC-MTDC[J].Power System Technology,2016,40(4):1037-1043(in Chinese).
[14]Gu Y,Xiang X,Li W,et al.Mode-adaptive decentralized control for renewable DC micro-grid with enhanced reliability and flexibility[J].IEEE Transactions on Power Electronics,2014,29(9):5072-5080.
[15]孙孝峰,王娟,田艳军,等.基于自调节下垂系数的DG逆变器控制[J].中国电机工程学报,2013,33(36):71-78.Sun Xiaofeng,Wang Juan,Tian Yanjun,et al.Control of DGconnected inverters based on self-adaptable adjustment of droop coefficient[J].Proceedings of the CSEE,2013,33(36):71-78(in Chinese).
[16]阎发友,汤广福,贺之渊,等.基于MMC的多端柔性直流输电系统改进下垂控制策略[J].中国电机工程学报,2014,34(3):397-404.Yan Fayou,Tang Guangfu,He Zhiyuan,et al.An improved droop control strategy for MMC-based VSC-MTDC systems[J].Proceedings of the CSEE,2014,34(3):397-404(in Chinese).
[17]刘瑜超,武健,刘怀远,等.基于自适应下垂调节的VSC-MTDC功率协调控制[J].中国电机工程学报,2016,36(1):40-48.Liu Yuchao,Wu Jian,Liu Huaiyuan,et al.Effective power sharing based on adaptive droop control method in VSC multi-terminal DCgrids[J].Proceedings of the CSEE,2016,36(1):40-48(in Chinese).
[18]Bianchi F D,Dom J L.Coordinated frequency control using MT-HVDC grids with wind power plants[J].IEEE Transactions on Sustainable Energy,2016,7(1):213-220.
[19]Phulpin Y.Communication-free inertia and frequency control for wind generators connected by an HVDC-link[J].IEEE Transactions on Power Systems,2012,27(2):1136-1137.
[20]仉雪娜,赵成勇,庞辉,等.基于MMC的多端直流输电系统直流侧故障控制保护策略[J].电力系统自动化,2013,37(15):140-145.Zahng Xuena,Zhao Chengyong,Pang Hui,et al.A control and protection scheme of multi-terminal DC transmission system based on MMC for DC line fault[J].Automation of Electric Power Systems,2013,37(15):140-145(in Chinese).
[21]王鹏伍,崔翔.MMC-HVDC三相解耦二次谐波环流抑制算法[J].电力系统自动化,2013,37(15):47-52.Wang Pengwu,Cui Xiang.Three phases decoupled second harmonic circulation current suppression algorithm for MMC-HVDC[J].Automation of Electric Power Systems,2013,37(15):47-52(in Chinese).
[22]徐政.柔性直流输电系统[M].北京:机械工业出版社,2016.
[23]Til K V,Jef B,Ronnie B,et al.A classification of DC node voltage control methods for HVDC grids[J].Electric Power Systems Research,2013(103):137-144.
[24]钱科军,袁越,Zhou Cheng-ke.分布式发电对配电网可靠性的影响研究[J].电网技术,2008,32(11):74-78.Qian Kejun,Yuan Yue,Zhou Cheng-ke.Study on impact of distributed generation on distribution system reliability[J].Power System Technology,2008,32(11):74-78(in Chinese).
[25]Sun Y,Teixeira C A,Holmes D G,et al.Low order circulating current suppression of PWM based modular multilevel converters using DC-link voltage compensation[J].IEEE Transactions on Power Electronics,2018:33(1):210-220.
[26]吕志鹏,盛万兴,钟庆昌,等.虚拟同步发电机及其在微电网中的应用[J].中国电机工程学报,2014,34(16):2591-2603.LüZhipeng,Sheng Wanxing,Zhong Qingchang,et al.Virtual synchronous generator and its applications in micro-grid[J].Proceedings of the CSEE,2014,34(16):2591-2603(in Chinese).
[27]阳岳希,杨杰,贺之渊,等.基于MMC的背靠背柔性直流输电系统控制策略[J].电力系统自动化,2017,41(4):120-124.Yang Yuexi,Yang Jie,He Zhiyuan,et al.Control strategy of MMCbased back-to-back HVDC transmission system[J].Automation of Electric Power Systems,2017,41(4):120-124(in Chinese).
[28]Ashabani M,Mohamed A R I,Mirsalim M,et al.Multivariable droop control of synchronous current converters in weak grids/microgrids with decoupled dq-axes currents[J].IEEE Transactions on Smart Grid,2015,6(4):1610-1620.
[29]Ashabani M,Mohamed A R I.Integrating VSCs to weak grids by nonlinear power damping controller with self-synchronization capability[J].IEEE Transactions on Power Systems,2014,29(2):805-814.
[30]王炜宇,李勇,曹一家,等.参与电网调频的多端柔性直流输电系统自适应下垂控制策略[J].电力系统自动化,2017,41(13):142-149.Wang Weiyu,Li Yong,Cao Yijia,et al.Adaptive droop control strategy participating in power grid frequency regulation for VSC-MTDC transmission system[J].Automation of Electric Power Systems,2017,41(13):142-149(in Chinese).
[2]Ef S,Vittal V,Heydt G T,et al.Impact of increased penetration of photovoltaic generation on power systems[J].IEEE Transactions on Power Systems,2013,28(2):893-901.
[3]赵波,王财胜,周金辉,等.主动配电网现状与未来发展[J].电力系统自动化,2014,38(18):125-135.Zhao Bo,Wang Caisheng,Zhou Jinhui,et al.Present and future development trend of active distribution network[J].Automation of Electric Power Systems,2014,38(18):125-135(in Chinese).
[4]Cao W,Wu J Z,Nick J.Operating principle of Soft Open Points for electrical distribution network operation[J].Applied Energy,2016(164):245-257.
[5]杨欢,蔡云旖,屈子森,等.配电网柔性开关设备关键技术及其发展趋势[J].电力系统自动化,2018,42(7):153-165.Yang Huan,Cai Yunyi,Qu Zisen,et al.Research on key techniques and development trend of soft open points for distribution network[J].Automation of Electric Power Systems,2018,42(7):153-165(in Chinese).
[6]王天昊,李鹏,于浩,等.变结构条件下智能配电软开关暂态快速仿真方法[J].电网技术,2018,42(7):2279-2285.Wang Tianhao,Li Peng,Yu Hao,et al.A fast algorithm of electromagnetic transient simulation for soft open points with variable structure conditions[J].Power System Technology,2018,42(7):2279-2285(in Chinese).
[7]Tang Y,Ran L,Alatise O,Mawby P.Capacitor selection for modular multilevel converter[J].IEEE Transactions on Industry Applications,2016,52(4):3279-3293.
[8]Gemmell B,Retzmann J D.Prospects of multilevel VSC technologies for power transmission[C]//IEEE PES Transmission and Distribution Conference and Exposition.Chicago,2008:1-16.
[9]杨晓峰,郑琼林,薛尧,等.模块化多电平换流器的拓扑和工业应用综述[J].电网技术,2016,40(1):1-10.Yang Xiaofeng,Zheng Qionglin,Xue Xiao,et al.Review on topology and industry applications of modular multilevel converter[J].Power System Technology,2016,40(1):1-10(in Chinese).
[10]周诗嘉,林卫星,姚良忠,等.两电平VSC与MMC通用型平均值仿真模型[J].电力系统自动化,2015,39(12):138-145.Zhou Shijia,Lin Weixing,Yao Liangzhong,et al.Generic averaged value models for two-level VSC and MMC[J].Automation of Electric Power Systems,2015,39(12):138-145(in Chinese).
[11]刘盼盼,荆龙,吴学智,等.一种MMC-MTDC系统新型协调控制策略[J].电网技术,2016,40(1):64-69.Liu Panpan,Jing Long,Wu Xuezhi,et al.A new coordinated control strategy for MMC-MTDC system and stability analysis[J].Power System Technology,2016,40(1):64-69(in Chinese).
[12]唐庚,徐政,刘昇,等.适用于多端柔性直流输电系统的新型直流电压控制策略[J].电力系统自动化,2013,37(15):125-132.Tang Geng,Xu Zheng,Liu Sheng,et al.A novel DC voltage control strategy for VSC MTDC systems[J].Automation of Electric Power Systems,2013,37(15):125-132(in Chinese).
[13]孙黎霞,陈宇,宋洪刚,等.适用于VSC-MTDC的改进直流电压下垂控制策略[J].电网技术,2016,40(4):1037-1043.Sun Lixia,Chen Yu,Song Hongang,et al.Improved voltage droop control strategy for VSC-MTDC[J].Power System Technology,2016,40(4):1037-1043(in Chinese).
[14]Gu Y,Xiang X,Li W,et al.Mode-adaptive decentralized control for renewable DC micro-grid with enhanced reliability and flexibility[J].IEEE Transactions on Power Electronics,2014,29(9):5072-5080.
[15]孙孝峰,王娟,田艳军,等.基于自调节下垂系数的DG逆变器控制[J].中国电机工程学报,2013,33(36):71-78.Sun Xiaofeng,Wang Juan,Tian Yanjun,et al.Control of DGconnected inverters based on self-adaptable adjustment of droop coefficient[J].Proceedings of the CSEE,2013,33(36):71-78(in Chinese).
[16]阎发友,汤广福,贺之渊,等.基于MMC的多端柔性直流输电系统改进下垂控制策略[J].中国电机工程学报,2014,34(3):397-404.Yan Fayou,Tang Guangfu,He Zhiyuan,et al.An improved droop control strategy for MMC-based VSC-MTDC systems[J].Proceedings of the CSEE,2014,34(3):397-404(in Chinese).
[17]刘瑜超,武健,刘怀远,等.基于自适应下垂调节的VSC-MTDC功率协调控制[J].中国电机工程学报,2016,36(1):40-48.Liu Yuchao,Wu Jian,Liu Huaiyuan,et al.Effective power sharing based on adaptive droop control method in VSC multi-terminal DCgrids[J].Proceedings of the CSEE,2016,36(1):40-48(in Chinese).
[18]Bianchi F D,Dom J L.Coordinated frequency control using MT-HVDC grids with wind power plants[J].IEEE Transactions on Sustainable Energy,2016,7(1):213-220.
[19]Phulpin Y.Communication-free inertia and frequency control for wind generators connected by an HVDC-link[J].IEEE Transactions on Power Systems,2012,27(2):1136-1137.
[20]仉雪娜,赵成勇,庞辉,等.基于MMC的多端直流输电系统直流侧故障控制保护策略[J].电力系统自动化,2013,37(15):140-145.Zahng Xuena,Zhao Chengyong,Pang Hui,et al.A control and protection scheme of multi-terminal DC transmission system based on MMC for DC line fault[J].Automation of Electric Power Systems,2013,37(15):140-145(in Chinese).
[21]王鹏伍,崔翔.MMC-HVDC三相解耦二次谐波环流抑制算法[J].电力系统自动化,2013,37(15):47-52.Wang Pengwu,Cui Xiang.Three phases decoupled second harmonic circulation current suppression algorithm for MMC-HVDC[J].Automation of Electric Power Systems,2013,37(15):47-52(in Chinese).
[22]徐政.柔性直流输电系统[M].北京:机械工业出版社,2016.
[23]Til K V,Jef B,Ronnie B,et al.A classification of DC node voltage control methods for HVDC grids[J].Electric Power Systems Research,2013(103):137-144.
[24]钱科军,袁越,Zhou Cheng-ke.分布式发电对配电网可靠性的影响研究[J].电网技术,2008,32(11):74-78.Qian Kejun,Yuan Yue,Zhou Cheng-ke.Study on impact of distributed generation on distribution system reliability[J].Power System Technology,2008,32(11):74-78(in Chinese).
[25]Sun Y,Teixeira C A,Holmes D G,et al.Low order circulating current suppression of PWM based modular multilevel converters using DC-link voltage compensation[J].IEEE Transactions on Power Electronics,2018:33(1):210-220.
[26]吕志鹏,盛万兴,钟庆昌,等.虚拟同步发电机及其在微电网中的应用[J].中国电机工程学报,2014,34(16):2591-2603.LüZhipeng,Sheng Wanxing,Zhong Qingchang,et al.Virtual synchronous generator and its applications in micro-grid[J].Proceedings of the CSEE,2014,34(16):2591-2603(in Chinese).
[27]阳岳希,杨杰,贺之渊,等.基于MMC的背靠背柔性直流输电系统控制策略[J].电力系统自动化,2017,41(4):120-124.Yang Yuexi,Yang Jie,He Zhiyuan,et al.Control strategy of MMCbased back-to-back HVDC transmission system[J].Automation of Electric Power Systems,2017,41(4):120-124(in Chinese).
[28]Ashabani M,Mohamed A R I,Mirsalim M,et al.Multivariable droop control of synchronous current converters in weak grids/microgrids with decoupled dq-axes currents[J].IEEE Transactions on Smart Grid,2015,6(4):1610-1620.
[29]Ashabani M,Mohamed A R I.Integrating VSCs to weak grids by nonlinear power damping controller with self-synchronization capability[J].IEEE Transactions on Power Systems,2014,29(2):805-814.
[30]王炜宇,李勇,曹一家,等.参与电网调频的多端柔性直流输电系统自适应下垂控制策略[J].电力系统自动化,2017,41(13):142-149.Wang Weiyu,Li Yong,Cao Yijia,et al.Adaptive droop control strategy participating in power grid frequency regulation for VSC-MTDC transmission system[J].Automation of Electric Power Systems,2017,41(13):142-149(in Chinese).