1.State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources (North China Electric Power University) Beijing 102206 China; 2.State Key Lab of Control and Simulation of Power Systems and Generation Equipments (Tsinghua University) Beijing 100084 China; 3.Beijing Sifang Automation Co.,Ltd. Beijing 100085 China
Abstract Traditional control strategies of high voltage direct current transmission based on modular multilevel converter (MMC-HVDC) have many shortcomings such as complicated control structures,the requirement of multiple PI regulators,rotating coordinate transformation and phase locked loop,and slow dynamic response under unbalanced grid voltage,etc.On the basis of the generalized power model of MMC-HVDC,the deadbeat direct power control method under unbalanced grid voltages is presented,which omits current inner loop so that the complicated reference current computation and multiple PI regulators and the tuning of their corresponding multiple parameters are avoided.This method can regulate active power and reactive power directly and has a fast dynamic response.The power compensation strategy is proposed to achieve three selective control objectives under unbalanced grid voltages,i.e.negative sequence current suppression,active power fluctuation suppression,and reactive power fluctuation suppression,respectively.The computation formulas of the power compensation components for three control objectives are given in this paper.The simulation platform of MMC-HVDC with 11 levels is built in PSCAD/EMTDC,and the simulation results verify the correctness and the effectiveness of the proposed method.
Liang Yingyu,Yang Qixun,Liu Jianzheng等. Deadbeat Direct Power Control for MMC-HVDC Under Unbalanced Grid Voltages[J]. Transactions of China Electrotechnical Society, 2015, 30(15): 15-25.
[1] Lesnicar A,Marquardt R.An innovative modular multilevel converter topology suitable for a wide power range[C].IEEE Bologna Power Tech Conference,Bologna,Italy,2003:23-26. [2] 杨晓峰,郑琼林.基于MMC环流模型的通用环流抑制策略[J].中国电机工程学报,2012,32(18):59-65. Yang Xiaofeng,Zheng Qionglin.A novel universal circulating current suppressing strategy based on the MMC circulating current model[J].Proceedings of the CSEE,2012,32(18):59-65. [3] 管敏渊,徐政.模块化多电平换流器型直流输电的建模与控制[J].电力系统自动化,2010,34(19):64-68. Guan Minyuan,Xu Zheng.Modeling and control of modular multilevel converter in HVDC transmission[J].Automation of Electric Power Systems,2010,34(19):64-68. [4] Song H S,Nam K.Dual current control scheme for PWM converter under unbalanced input voltage conditions[J].IEEE Transactions on Industrial Electronics,1999,46(5):953-959. [5] 皇甫成,贺之渊,汤广福,等.交流电网不平衡情况下电压源换相直流输电系统的控制策略[J].中国电机工程学报,2008,28(22):144-151. Huang Fucheng,He Zhiyuan,Tang Guangfu,et al.Control strategy for the voltage source converter based HVDC transmission system under unbalanced AC grid conditions[J].Proceedings of the CSEE,2008,28(22):144-151. [6] 魏晓云,孙辉,魏晓光,等.改善电能质量的电压源换流器高压直流输电不平衡控制策略[J].中国电机工程学报,2011,31(9):8-14. Wei Xiaoyun,Sun Hui,Wei Xiaoguang,et al.Control strategy about power quality improvement for VSC-HVDC under unbalanced AC grid conditions[J].Proceedings of the CSEE,2011,31(9):8-14. [7] 章玮,王宏胜,任远,等.不对称电网电压条件下三相并网型逆变器的控制[J].电工技术学报,2010,25(12):103-110. Zhang Wei,Wang Hongsheng,Ren Yuan,et al.Investigation on control of three-phase grid-connected inverters under unbalanced grid voltage conditions[J].Transactions of China Electrotechnical Society,2010,25(12):103-110. [8] 张建坡,赵成勇,敬华兵.比例谐振控制器在MMC-HVDC控制中的仿真研究[J].中国电机工程学报,2013,33(21):53-62. Zhang Jianpo,Zhao Chengyong,Jing Huabing.Simulating research of proportional resonant controllers in MMC-HVDC[J].Proceedings of the CSEE,2013,33(21):53-62. [9] Zhou Y,Jiang D,Guo J,et al.Analysis and control of modular multilevel converters under unbalanced conditions[J].IEEE Transactions on Power Delivery,2013,28(4):1986-1995. [10]Moon J W,Kim C S,Park J W,et al.Circulating current control in MMC under the unbalanced voltage[J].IEEE Transactions on Power Delivery,2013,28(3):1952-1959. [11]张永昌,谢伟,李正熙.PWM整流器预测无差拍直接功率控制[J].电机与控制学报,2013,17(12):57-63. Zhang Yongchang,Xie Wei,Li Zhengxi.Predictive deadbeat direct power control of PWM rectifier[J].Electric Machines and Control,2013,17(12):57-63. [12]Hu J,Zhu J,Dorrell D G.Model-predictive direct power control of doubly-fed induction generators under unbalanced grid voltage conditions in wind energy applications[J].IET Renewable Power Generation,2014,8(6):687-695. [13]Hu J,Zhu J,Dorrell D G.In-depth study of direct power control strategies for power converters[J].IET Power Electronics,2014,7(7):1810-1820. [14]孙丹,方扬,孙士涛,等.双馈异步风力发电机无差拍直接功率控制及延时补偿[J].电工技术学报,2013,28(11):70-78. Sun Dan,Fang Yang,Sun Shitao,et al.Dead-beat direct power control of doubly fed induction generators with delay compensation[J].Transactions of China Electrotechnical Society,2013,28(11):70-78. [15]Mattavelli P.An improved deadbeat control for UPS using disturbance observers[J].IEEE Transactions on Industrial Electronics,2005,52(1):206-212. [16]管敏渊,徐政,屠卿瑞,等.模块化多电平换流器型直流输电的调制策略[J].电力系统自动化,2010,34(2):48-52. Guan Minyuan,Xu Zheng,Tu Qingrui,et al.Nearest level modulation for modular multilevel converters in HVDC transmission[J].Automation of Electric Power Systems,2010,34(2):48-52. [17]Tu Q,Xu Z,Xu L.Reduced switching-frequency modulation and circulating current suppression for modular multilevel converters[J].IEEE Transactions on Power Delivery,2011,26(3):2009-2017. [18]Shang L,Hu J.Sliding-mode-based direct power control of grid-Connected wind-turbine-driven doubly fed induction generators under unbalanced grid voltage conditions[J].IEEE Transactions on Energy Conversion,2012,27(2):362-373. [19]魏晓云,卢颖.电网不平衡时电压源换流器高压直流输电统一控制策略[J].中国电机工程学报,2012,32(34):50-57. Wei Xiaoyun,Lu Ying.A unified control strategy for VSC-HVDC under unbalanced grid conditions[J].Proceedings of the CSEE,2012,32(34):50-57. [20]Tang L,Ooi B T.Elimination of “harmonic transfer through converters” in VSC-based multiterminal DC systems by AC/DC decoupling[J].IEEE Transactions on Power Delivery,2008,23(1):402-409.
2015, Vol. 30 
