不平衡电压下VSG无锁相环并网及运行控制策略
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摘要
针对并网逆变器在不平衡电压下电流畸变严重和锁相环节复杂等问题,文中设计了一种基于改进虚拟同步机(VSG)的逆变器无锁相环控制策略。重点研究了VSG在不平衡电网电压下的运行控制方法,设计了一种基于比例积分谐振(PIR)控制器的改进VSG控制策略,在不改变VSG外特性的基础上有效抑制了逆变器输出电流的不平衡分量。同时,提出一种基于虚拟功率的VSG预同步控制策略,保证VSG孤岛转并网模式的无缝切换。整个控制过程不依赖锁相环,避免了锁相环对系统控制精度以及响应速度的影响,降低了控制系统的复杂度。最后,基于RT-LAB的实时仿真平台对所提控制策略进行了验证。
In order to solve the problem of the current distortion under unbalanced voltage and the complexity of the phaselocked loop( PLL) of the grid-connected inverter,a strategy based on virtual synchronous generator( VSG) under unbalanced grid voltage without PLL is proposed. The control method of VSG under unbalanced grid voltage is detailed studied. An improved VSG control strategy based on PIR current control loop is designed to restrain current distortion effectively without changing output characteristics. Meanwhile,a VSG resynchronization control strategy based on virtual power is proposed to guarantee seamless switches between grid-connection mode and off-grid mode. The PLL is not used throughout the proposed strategy,which avoids the bad effect of PLL on control precision and response speed and makes the control system simplified in addition. Finally,a real-time simulation platform based on RT-LAB is built to verify the proposed control strategy.
In order to solve the problem of the current distortion under unbalanced voltage and the complexity of the phaselocked loop( PLL) of the grid-connected inverter,a strategy based on virtual synchronous generator( VSG) under unbalanced grid voltage without PLL is proposed. The control method of VSG under unbalanced grid voltage is detailed studied. An improved VSG control strategy based on PIR current control loop is designed to restrain current distortion effectively without changing output characteristics. Meanwhile,a VSG resynchronization control strategy based on virtual power is proposed to guarantee seamless switches between grid-connection mode and off-grid mode. The PLL is not used throughout the proposed strategy,which avoids the bad effect of PLL on control precision and response speed and makes the control system simplified in addition. Finally,a real-time simulation platform based on RT-LAB is built to verify the proposed control strategy.
引文
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[12] DONG D,WEN B,BOROYEVICH D,et al. Analysis of phase-locked loop low-frequency stability in three-phase gridconnected power converters considering impedance interactions[J]. IEEE Transactions on Industrial Electronics,2015,62(1):310-321.
[13]ZHONG Q C,NGUYEN P L,MA Z,et al. Self-synchronized synchronverters:inverters without a dedicated synchronization unit[J]. IEEE Transactions on Power Electronics,2013,29(2):617-630.
[14]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(16):2591-2603.LYU Zhipeng,SHENG Wanxing,ZHONG Qingchang,et al.Virtual synchronous generator and its applications in micro-grid[J]. Proceedings of the CSEE,2014(16):2591-2603.
[15]赤木泰文,埃德森,毛立赛.瞬时功率理论及其在电力调节中的应用[M].北京:机械工业出版社,2009:16-33.AKAGI H,WATANABE E H,AREDES M. Instantaneous power theory and applications to power conditioning[M]. Beijing:China Machine Press,2009:16-33.
[16] YE Y,KAZERANI M,QUINTANA V H. A novel modeling and control method for three-phase PWM converters[C]∥IEEE Power Electronics Specialists Conference. Vancouver,BC:IEEE,2001:102-107.
[2]薛晨,黎灿兵,曹一家,等.智能电网中的电网友好技术概述及展望[J].电力系统自动化,2011,35(15):102-107.XUE Chen,LI Canbing,CAO Yijia,et al. An overview and prospects of grid friendly technology in smart grid[J]. Automation of Electric Power Systems,2011,35(15):102-107.
[3]ZHONG Q C,WEISS G. Synchronverters:inverters that mimic synchronous generators[J]. IEEE Transactions on Industrial Electronics,2011,58(4):1259-1267.
[4]何光辉,张仰飞,陈光宇,等.基于虚拟同步电机的负荷换流器建模及参数设计[J].电力工程技术,2018,37(1):79-85,108.HE Guanghui,ZHANG Yangfei,CHEN Guangyu,et al. Modeling and parameter design of load converter based on virtual synchronous motor[J]. Electric Power Engineering Technology,2018,37(1):79-85,108.
[5]HIRASE Y,SUGIMOTO K,SAKIMOTO K,et al. Analysis of resonance in microgrids and effects of system frequency stabilization using a virtual synchronous generator[J]. IEEE Journal of Emerging&Selected Topics in Power Electronics,2016,4(4):1287-1298.
[6]王逸超,欧名勇,陈燕东,等.不平衡电压下并网逆变器的功率波动抑制与电流平衡协调控制方法[J].中国电机工程学报,2017,37(23):6981-6987,7089.WANG Yichao,OU Mingyong,CHEN Yandong,et al. Coordinate control of power fluctuation suppression and current balance under unbalanced voltage conditions[J]. Proceedings of the CSEE,2017,37(23):6981-6987,7089.
[7]郭小强,张学,卢志刚,等.不平衡电网电压下光伏并网逆变器功率/电流质量协调控制策略[J].中国电机工程学报,2014,34(3):346-353.GUO Xiaoqiang,ZHANG Xue,LU Zhigang,et al. Coordinate control of power and current quality for grid-connected PV inverters under unbalanced grid voltage[J]. Proceedings of the CSEE. 2014,34(3):346-353.
[8]万晓凤,胡海林,聂晓艺,等.电网电压不平衡时的改进虚拟同步机控制策略[J].电网技术,2017,41(11):3573-3581.WAN Xiaofeng,HU Hailin,NIE Xiaoyi,et al. An improved control strategy for virtual synchronous generator under unbalanced grid voltage[J]. Power System Technology,2017,41(11):3573-3581.
[9]顾彬仕,王建华,骆芳芳,等.三相四桥臂虚拟同步发电机预同步、多环路控制及负载不平衡控制方法[J].电工技术学报,2017,32(S1):138-150.GU Binshi,WANG Jianhua,LUO Fangfang,et al. A pre-synchronization, multiple loops control, and unbalanced load control strategies for three-phase four-leg virtual synchronous generator[J]. Transactions of China Electrotechnical Society,2017,32(S1):138-150.
[10] AHN S C,HYUN D S. New control scheme of three-phase PWM AC/DC converter without phase angle detection under the unbalanced input voltage conditions[J]. IEEE Transactions on Power Electronics,2002,17(5):616-622.
[11]雷芸,肖岚,郑昕昕.不平衡电网下无锁相环三相并网逆变器控制策略[J].中国电机工程学报,2015,35(18):4744-4752.LEI Yun,XIAO Lan,ZHENG Xinxin. Control strategies of three-phase grid-connected inverters without phase-lock loop under unbalanced grids[J]. Proceedings of the CSEE,2015,35(18):4744-4752.
[12] DONG D,WEN B,BOROYEVICH D,et al. Analysis of phase-locked loop low-frequency stability in three-phase gridconnected power converters considering impedance interactions[J]. IEEE Transactions on Industrial Electronics,2015,62(1):310-321.
[13]ZHONG Q C,NGUYEN P L,MA Z,et al. Self-synchronized synchronverters:inverters without a dedicated synchronization unit[J]. IEEE Transactions on Power Electronics,2013,29(2):617-630.
[14]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(16):2591-2603.LYU Zhipeng,SHENG Wanxing,ZHONG Qingchang,et al.Virtual synchronous generator and its applications in micro-grid[J]. Proceedings of the CSEE,2014(16):2591-2603.
[15]赤木泰文,埃德森,毛立赛.瞬时功率理论及其在电力调节中的应用[M].北京:机械工业出版社,2009:16-33.AKAGI H,WATANABE E H,AREDES M. Instantaneous power theory and applications to power conditioning[M]. Beijing:China Machine Press,2009:16-33.
[16] YE Y,KAZERANI M,QUINTANA V H. A novel modeling and control method for three-phase PWM converters[C]∥IEEE Power Electronics Specialists Conference. Vancouver,BC:IEEE,2001:102-107.