基于OPF的MMC-MTDC自适应下垂控制策略
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摘要
传统下垂控制无法解决模块化多电平换流器多端直流MMC-MTDC(modular multilevel converter multiterminal DC)输电系统中换流站功率裕度和系统功率协调分配的问题,为此提出一种最优潮流下自适应下垂控制策略。首先根据电压变化方向与实时裕度设计MMC自适应下垂控制器;然后分析传统下垂控制无法解决MTDC中直流线路阻抗产生电压偏差的缺陷,针对影响直流网络潮流的因素,构建约束条件以及目标函数求解潮流优化分配下垂系数;最后通过直流电压差值实时计算权衡系数来分配两种下垂曲线所占比例。在PSCAD/EMTDC中建立5端MTDC模型,分别在稳态与暂态工况下对比两种控制方式,结果表明该控制策略可以避免换流站满载、减少线路损耗实现系统功率优化分配。
The traditional droop control cannot solve the coordinated allocation problem of power margin for a converter station and the system power in a modular multilevel converter multi-terminal DC(MMC-MTDC) transmission system. Accordingly, an adaptive droop control strategy based on optimal power flow is proposed in this paper. First, an adaptive droop controller is designed according to the change in voltage direction and real-time margin. Then, the defect of the traditional droop control, i.e., it cannot solve the voltage deviation resulting from the DC line impedance in MTDC,is analyzed. In consideration of factors that affect the power flow in the DC network, the constraint conditions and objective function are constructed to obtain the droop coefficient of power flow optimal allocation. Finally, the proportions of two kinds of droop curves are allocated by calculating the trade-off coefficient in real-time with DC voltage deviations. A five-terminal MMC model is established in PSCAD/EMTDC, and two control methods are compared in steady-and transient-state working conditions. Results show that the proposed control strategy can avoid full load on the converter station and reduce the line loss, thus achieving optimal power allocation of the system.
The traditional droop control cannot solve the coordinated allocation problem of power margin for a converter station and the system power in a modular multilevel converter multi-terminal DC(MMC-MTDC) transmission system. Accordingly, an adaptive droop control strategy based on optimal power flow is proposed in this paper. First, an adaptive droop controller is designed according to the change in voltage direction and real-time margin. Then, the defect of the traditional droop control, i.e., it cannot solve the voltage deviation resulting from the DC line impedance in MTDC,is analyzed. In consideration of factors that affect the power flow in the DC network, the constraint conditions and objective function are constructed to obtain the droop coefficient of power flow optimal allocation. Finally, the proportions of two kinds of droop curves are allocated by calculating the trade-off coefficient in real-time with DC voltage deviations. A five-terminal MMC model is established in PSCAD/EMTDC, and two control methods are compared in steady-and transient-state working conditions. Results show that the proposed control strategy can avoid full load on the converter station and reduce the line loss, thus achieving optimal power allocation of the system.
引文
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[7]张芳,李清泉,李传栋.含VSC-MTDC的交直流系统潮流控制算法[J].电力系统及其自动化学报, 2017, 29(2):62-70.Zhang Fang, Li Qingquan, Li Chuandong. Power flow control algorithm for AC/DC system with VSC-MTDC[J]. Proceedings of the CSU-EPSA, 2017, 29(2):62-70(in Chinese).
[8]陈朋,李梅航,严兵,等.灵活裕度控制策略的功率-电压特性曲线分析[J].高电压技术, 2016, 42(10):3126-3132.Chen Peng, Li Meihang, Yan Bing, et al. Analysis of power-voltage characteristics of flexible margin control strategy[J]. High Voltage Engineering, 2016, 42(10):3126-3132(in Chinese).
[9] Cao Jun, Du Wenjuan, Wang Haifeng, et al. Minimization of transmission loss in meshed AC/DC grids with VSCMTDC networks[J]. IEEE Transactions on Power Systems,2013, 28(3):3047-3055(in Chinese).
[10]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 DC grids[J]. Proceedings of the CSEE, 2016,36(1):40-48(in Chinese).
[11]张海波,袁志昌,赵宇明,等. VSC-MTDC系统变截距直流电压下垂控制策略[J].电力自动化设备, 2016, 36(10):60-64.Zhang Haibo, Yuan Zhicahng, Zhao Yuming, et al. Variable intercept DC-voltage droop control for VSC-MTDC system[J]. Elcetric Power Automation Equipment, 2016, 36(10):60-64(in Chinese).
[12]罗永捷,李耀华,王平,等.多端柔性直流输电系统直流电压自适应下垂控制策略研究[J].中国电机工程学报, 2016,36(10):2588-2599.Luo Yongjie, Li Yaohua, Wang Ping, et al. DC voltage adaptive droop control of multi-terminal HVDC systems[J].Proceedings of the CSEE, 2016, 36(10):2588-2599(in Chinese).
[13]冉晓洪,苗世洪,吴英杰,等.基于最优功率分配的多端直流网络改进下垂控制策略[J].电工技术学报, 2016, 31(9):16-24.Ran Xiaohong, Miao Shihong, Wu Yingjie, et al. An improved droop control strategy for multi-terminal DC grids based on optimal active power allocation[J]. Transactions of China Electrotechnical Society, 2016, 31(9):16-24(in Chinese).
[14]方斯顿,程浩忠,徐国栋,等.随机最优潮流及其应用的研究综述[J].电力自动化设备, 2016, 36(11):1-10.Fang Sidun, Cheng Haozhong, Xu Guodong, et al. Reviews on stochastic optimal power flow and its application[J].Electric Power Automation Equipment, 2016, 36(11):1-10(in Chinese).
[15] Yang Minxia, Xie Da, Zhu Hui, et al. Ar chitectures and control for multi-terminal DC(MTDC)distribution network a review[C]. 11th IET International Conference on AC and DC Power Transmission, Birmingham, UK, 2015:1-7.
[16] Chaudhuri N R, Chaudhuri B. Adaptive droop control for effective power sharing in multi-terminal DC(MTDC)grids[J]. IEEE Transactions on Power Systems, 2013, 28(1):21-29.
[17] Abdel-Khalik A S, Massoud A M, Elserougi A A, et al. Optimum power transmission-based droop control design for multi-terminal HVDC of offshore wind farms[J]. IEEE Transactions on Power Systems, 2013, 28(3):3401-3409.
[18] Zhao Xiaodong, Li Kang. Droop setting design for multiterminal HVDC grids considering voltage deviation impacts[J]. Electric Power Systems Research, 2015, 123:67-75.
[19] Wang Feng, Tjernberg L B, Le A T, et al. An extended OPF incorporating multi-terminal VSC-HVDC and its application on transmission loss evaluation[C]. 2013 IEEE Grenoble Conference. Grenoble, France, 2013:1-6.
[2]温家良,葛俊,潘艳,等.直流电网用电力电子器件发展与展望[J].电网技术, 2016, 40(3):663-669.Wen Jialiang, Ge Jun, Pan Yan, et al. Development and expectation of power electronic devices for DC grid[J].Power System Technology, 2016, 40(3):663-669(in Chinese).
[3]宋平岗,吴继珍,陈欢,等.单相MMC变流器及其在新型牵引供电系统中应用的研究[J].电源学报, 2015, 13(6):92-100.Song Pinggang, Wu Jizhen, Chen Huan, et al. Research on single-phase MMC and its application in novel traction power supply system[J]. Journal of Power Supply, 2015, 13(6):92-100(in Chinese).
[4]李兴源,曾琦,王渝红,等.柔性直流输电系统控制研究综述[J].高电压技术, 2016, 42(10):3025-3037.Li Xingyuan, Zeng Qi, Wang Yuhong, et al. Control strategies of voltage source converter based direct current transmission system[J]. High Voltage Engineering, 2016, 42(10):3025-3037(in Chinese).
[5]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 Honggang, et al. Improved voltage droop control strategy for VSC-MTDC[J]. Power System Technology, 2016, 40(4):1037-1043(in Chinese).
[6]刘先正,温家良,潘艳,等.采用改进粒子群算法的直流电网最优潮流控制[J].电网技术, 2017, 41(3):715-720.Liu Xianzheng, Wen Jialiang, Pan Yan, et al. OPF control of DC-Grid using improved PSO algorithm[J]. Power System Technology, 2017, 41(3):715-720(in Chinese).
[7]张芳,李清泉,李传栋.含VSC-MTDC的交直流系统潮流控制算法[J].电力系统及其自动化学报, 2017, 29(2):62-70.Zhang Fang, Li Qingquan, Li Chuandong. Power flow control algorithm for AC/DC system with VSC-MTDC[J]. Proceedings of the CSU-EPSA, 2017, 29(2):62-70(in Chinese).
[8]陈朋,李梅航,严兵,等.灵活裕度控制策略的功率-电压特性曲线分析[J].高电压技术, 2016, 42(10):3126-3132.Chen Peng, Li Meihang, Yan Bing, et al. Analysis of power-voltage characteristics of flexible margin control strategy[J]. High Voltage Engineering, 2016, 42(10):3126-3132(in Chinese).
[9] Cao Jun, Du Wenjuan, Wang Haifeng, et al. Minimization of transmission loss in meshed AC/DC grids with VSCMTDC networks[J]. IEEE Transactions on Power Systems,2013, 28(3):3047-3055(in Chinese).
[10]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 DC grids[J]. Proceedings of the CSEE, 2016,36(1):40-48(in Chinese).
[11]张海波,袁志昌,赵宇明,等. VSC-MTDC系统变截距直流电压下垂控制策略[J].电力自动化设备, 2016, 36(10):60-64.Zhang Haibo, Yuan Zhicahng, Zhao Yuming, et al. Variable intercept DC-voltage droop control for VSC-MTDC system[J]. Elcetric Power Automation Equipment, 2016, 36(10):60-64(in Chinese).
[12]罗永捷,李耀华,王平,等.多端柔性直流输电系统直流电压自适应下垂控制策略研究[J].中国电机工程学报, 2016,36(10):2588-2599.Luo Yongjie, Li Yaohua, Wang Ping, et al. DC voltage adaptive droop control of multi-terminal HVDC systems[J].Proceedings of the CSEE, 2016, 36(10):2588-2599(in Chinese).
[13]冉晓洪,苗世洪,吴英杰,等.基于最优功率分配的多端直流网络改进下垂控制策略[J].电工技术学报, 2016, 31(9):16-24.Ran Xiaohong, Miao Shihong, Wu Yingjie, et al. An improved droop control strategy for multi-terminal DC grids based on optimal active power allocation[J]. Transactions of China Electrotechnical Society, 2016, 31(9):16-24(in Chinese).
[14]方斯顿,程浩忠,徐国栋,等.随机最优潮流及其应用的研究综述[J].电力自动化设备, 2016, 36(11):1-10.Fang Sidun, Cheng Haozhong, Xu Guodong, et al. Reviews on stochastic optimal power flow and its application[J].Electric Power Automation Equipment, 2016, 36(11):1-10(in Chinese).
[15] Yang Minxia, Xie Da, Zhu Hui, et al. Ar chitectures and control for multi-terminal DC(MTDC)distribution network a review[C]. 11th IET International Conference on AC and DC Power Transmission, Birmingham, UK, 2015:1-7.
[16] Chaudhuri N R, Chaudhuri B. Adaptive droop control for effective power sharing in multi-terminal DC(MTDC)grids[J]. IEEE Transactions on Power Systems, 2013, 28(1):21-29.
[17] Abdel-Khalik A S, Massoud A M, Elserougi A A, et al. Optimum power transmission-based droop control design for multi-terminal HVDC of offshore wind farms[J]. IEEE Transactions on Power Systems, 2013, 28(3):3401-3409.
[18] Zhao Xiaodong, Li Kang. Droop setting design for multiterminal HVDC grids considering voltage deviation impacts[J]. Electric Power Systems Research, 2015, 123:67-75.
[19] Wang Feng, Tjernberg L B, Le A T, et al. An extended OPF incorporating multi-terminal VSC-HVDC and its application on transmission loss evaluation[C]. 2013 IEEE Grenoble Conference. Grenoble, France, 2013:1-6.