不平衡与非线性混合负载下的虚拟同步发电机控制策略
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摘要
基于虚拟同步发电机(virtual synchronous generator,VSG)控制的电压源型逆变器通常用作微网中各种分布式电源的接口,在孤岛模式下,微网的电压与频率易受不平衡与非线性混合负载的影响。为解决此问题,该文提出一种电压不平衡和谐波抑制的综合控制策略。首先,建立VSG在两相静止(αβ)坐标系下的等效阻抗模型,分析输出阻抗对系统供电质量的影响;其次,提出基于级联广义积分器(cascaded general-integrator,CGI)的虚拟阻抗实现方法,改善抑制效果,可避免对输出电流求导,提高系统动态性能与谐波抑制能力。然后,采用PI+多谐振并联(PIR)电压控制器对输出电压不平衡与谐波进行抑制。最后,对所提的控制策略进行仿真和实验研究,结果验证了所述控制策略在电压不平衡与谐波抑制方面的正确性与有效性。
Voltage source inverters based on virtual synchronous generator(VSG) control are usually used for all kinds of distributed generation interfaces in a microgrid, but the voltage and frequency of the microgird can be deteriorated under unbalanced and nonlinear mixed loads when the utility fails. A voltage unbalance and harmonics compensation strategy for the VSG in islanded microgrids was proposed. Firstly, the VSG equivalent impedance model was built to illustrate the effect of the output impedance on the system power quality in a two-phase stationary reference frame(αβ-SRF). Besides, a cascaded general-integrator(CGI) scheme was proposed to implement the virtual impedance to improve the compensation effect, which can avoid performing the time derivative function of output currents and increasing the dynamic response speed of the system significantly. Furthermore, the PI plus multi-resonant(PIR) voltage controller was used to compensate for the unbalanced and distorted output voltages of the VSG. Finally, the proposed strategy was demonstrated in detail and validated with a two 100-k VA VSGs parallel system under unbalanced and nonlinear loads.
Voltage source inverters based on virtual synchronous generator(VSG) control are usually used for all kinds of distributed generation interfaces in a microgrid, but the voltage and frequency of the microgird can be deteriorated under unbalanced and nonlinear mixed loads when the utility fails. A voltage unbalance and harmonics compensation strategy for the VSG in islanded microgrids was proposed. Firstly, the VSG equivalent impedance model was built to illustrate the effect of the output impedance on the system power quality in a two-phase stationary reference frame(αβ-SRF). Besides, a cascaded general-integrator(CGI) scheme was proposed to implement the virtual impedance to improve the compensation effect, which can avoid performing the time derivative function of output currents and increasing the dynamic response speed of the system significantly. Furthermore, the PI plus multi-resonant(PIR) voltage controller was used to compensate for the unbalanced and distorted output voltages of the VSG. Finally, the proposed strategy was demonstrated in detail and validated with a two 100-k VA VSGs parallel system under unbalanced and nonlinear loads.
引文
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[12]张平,石健将,李荣贵,等.低压微网逆变器的“虚拟负阻抗”控制策略[J].中国电机工程学报,2014,34(12):1844-1852.Zhang Ping,Shi Jianjiang,Li Ronggui,et al.A control strategy of“virtual negative”impedance for inverters in low-voltage microgrid[J].Proceedings of the CSEE,2014,34(12):1844-1852(in Chinese).
[13]Guerrero J M,Matas J,De Vicuna L G,et al.Decentralized control for parallel operation of distributed generation inverters using resistive output impedance[J].IEEE Transactions on Industrial Electronics,2007,54(2):994-1004.
[14]Zhong Qingchang.Robust droop controller for accurate proportional load sharing among inverters operated in parallel[J].IEEE Transactions on Industrial Electronics,2013,60(4):1281-1290.
[15]Yao Wei,Chen Min,Matas J,et al.Design and analysis of the droop control method for parallel inverters considering the impact of the complex impedance on the power sharing[J].IEEE Transactions on Industrial Electronics,2011,58(2):576-588.
[16]Matas J,Castilla M,de Vicu?a L G,et al.Virtual impedance loop for droop-controlled single-phase parallel inverters using a second-order general-integrator scheme[J].IEEE Transactions on Power Electronics,2010,25(12):2993-3002.
[17]黄媛,罗安,陈燕东,等.一种三阶广义积分交叉对消电流反馈控制的多逆变器并联控制策略[J].中国电机工程学报,2014,34(28):4855-4864.Huang Yuan,Luo An,Chen Yandong,et al.A current feedback control strategy for parallel operation of multi-inverters using third-order general-integrator crossover cancellation method[J].Proceedings of the CSEE,2014,34(28):4855-4864(in Chinese).
[18]Shi Rongliang,Zhang Xing,Liu Fang,et al.A dynamic voltage transient suppression control strategy for microgrid inverter[C]//Proceeding of International Electronics and Application Conference and Exposition.Shanghai,China:IEEE,2014:205-209.
[19]Shi Rongliang,Zhang Xing,Xu Haizhen,et al.Research on the synchronization control strategy for microgrid inverter[C]//Proceeding of International Electronics and Application Conference and Exposition.Shanghai,China:IEEE,2014:210-213.
[20]陈宏志,王旭,刘建昌.基于虚拟电阻匹配模式的逆变器并联方案[J].中国电机工程学报,2012,32(6):24-32.Chen Hongzhi,Wang Xu,Liu Jiangchang.Current sharing method for parallel inverters based impedance matching mode[J].Proceedings of the CSEE,2012,32(6):24-32(in Chinese).
[21]Liu Quanwei,Tao Yong,Liu Xunhao,et al.Voltage unbalance and harmonics compensation for islanded microgrid inverters[J].IET Power Electronics,2014,7(5):1055-1063.
[2]杨新法,苏剑,吕志鹏,等.微电网技术综述[J].中国电机工程学报,2014,34(1):57-70.Yang Xinfa,Su Jian,LüZhipeng,et al.Overview on micro-grid technology[J].Proceeding of the CSEE,2014,34(1):57-70(in Chinese).
[3]丁明,陈忠,苏建徽,等.可再生能源发电中的电池储能系统综述[J].电力系统自动化,2013,37(1):19-25.Ding Ming,Chen Zhong,Su Jianhui,et al.An overview of battery energy storage system for renewable energy generation[J].Automation of Electric Power Systems,2013,37(1):19-25(in Chinese).
[4]王成山,肖朝霞,王守相.微网综合控制与分析[J].电力系统自动化,2008,32(7):98-103.Wang Chengshan,Xiao Zhaoxia,Wang Shouxiang.Synthetical control and analysis of microgrid[J].Automation of Electric Power Systems,2008,32(7):98-103(in Chinese).
[5]王赞,肖岚,姚志垒,等.并网独立双模式控制高性能逆变器设计与实现[J].中国电机工程学报,2007,27(1):54-59.Wang Zan,Xiao Lan,Yao Zhilei,et al.Design and implementation of a high performance utility-interactive inverter[J].Proceedings of the CSEE,2007,27(1):54-59(in Chinese).
[6]He Jinwei,Li Yunwei.Generalized closed-loop control schemes with embedded virtual impedances for voltage source converters with LC or LCL filters[J].IEEETransactions on Power Electronics,2012,27(4):1850-1861.
[7]Vasquez J C,Guerrero J M,Luna A,et al.Adaptive droop control applied to voltage-source inverters operating in grid-connected and islanded modes[J].IEEE Transactions on Industrial Electronics,2009,56(10):4088-4096.
[8]Zhong Qingchang,Weiss G.Synchronverters:inverters that mimic synchronous generators[J].IEEE Transactions on Industrial Electronics,2011,58(4):1259-1267.
[9]张兴,朱德斌,徐海珍.分布式发电中的虚拟同步发电机技术[J].电源学报,2012,(3):1-6,12.Zhang Xing,Zhu Debin,Xu Haizhen.Review of virtual synchronous generator technology in distributed generation[J].Journal of Power Supply,2012,(3):1-6,12(in Chinese).
[10]Li Yunwei,Kao C N.An accurate power control strategy for power-electronics-interfaced distributed generation units operating in a low-voltage multibus microgrid[J].IEEE Transaction on Power Electronics,2009,24(12):2977-2988.
[11]Guerrero J M,De Vicuna L G,Matas J,et al.Output impedance design of parallel-connected UPS inverters with wireless load-sharing control[J].IEEE Transactions on Industrial Electronics,2005,52(4):1126-1135.
[12]张平,石健将,李荣贵,等.低压微网逆变器的“虚拟负阻抗”控制策略[J].中国电机工程学报,2014,34(12):1844-1852.Zhang Ping,Shi Jianjiang,Li Ronggui,et al.A control strategy of“virtual negative”impedance for inverters in low-voltage microgrid[J].Proceedings of the CSEE,2014,34(12):1844-1852(in Chinese).
[13]Guerrero J M,Matas J,De Vicuna L G,et al.Decentralized control for parallel operation of distributed generation inverters using resistive output impedance[J].IEEE Transactions on Industrial Electronics,2007,54(2):994-1004.
[14]Zhong Qingchang.Robust droop controller for accurate proportional load sharing among inverters operated in parallel[J].IEEE Transactions on Industrial Electronics,2013,60(4):1281-1290.
[15]Yao Wei,Chen Min,Matas J,et al.Design and analysis of the droop control method for parallel inverters considering the impact of the complex impedance on the power sharing[J].IEEE Transactions on Industrial Electronics,2011,58(2):576-588.
[16]Matas J,Castilla M,de Vicu?a L G,et al.Virtual impedance loop for droop-controlled single-phase parallel inverters using a second-order general-integrator scheme[J].IEEE Transactions on Power Electronics,2010,25(12):2993-3002.
[17]黄媛,罗安,陈燕东,等.一种三阶广义积分交叉对消电流反馈控制的多逆变器并联控制策略[J].中国电机工程学报,2014,34(28):4855-4864.Huang Yuan,Luo An,Chen Yandong,et al.A current feedback control strategy for parallel operation of multi-inverters using third-order general-integrator crossover cancellation method[J].Proceedings of the CSEE,2014,34(28):4855-4864(in Chinese).
[18]Shi Rongliang,Zhang Xing,Liu Fang,et al.A dynamic voltage transient suppression control strategy for microgrid inverter[C]//Proceeding of International Electronics and Application Conference and Exposition.Shanghai,China:IEEE,2014:205-209.
[19]Shi Rongliang,Zhang Xing,Xu Haizhen,et al.Research on the synchronization control strategy for microgrid inverter[C]//Proceeding of International Electronics and Application Conference and Exposition.Shanghai,China:IEEE,2014:210-213.
[20]陈宏志,王旭,刘建昌.基于虚拟电阻匹配模式的逆变器并联方案[J].中国电机工程学报,2012,32(6):24-32.Chen Hongzhi,Wang Xu,Liu Jiangchang.Current sharing method for parallel inverters based impedance matching mode[J].Proceedings of the CSEE,2012,32(6):24-32(in Chinese).
[21]Liu Quanwei,Tao Yong,Liu Xunhao,et al.Voltage unbalance and harmonics compensation for islanded microgrid inverters[J].IET Power Electronics,2014,7(5):1055-1063.