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
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摘要
当电网电压三相不对称时,并网逆变器输出功率恒定和输出电流平衡正序无法同时实现。首先探讨了瞬时有功/无功控制策略和平衡正序控制策略之间的内在联系,分析影响功率波动和电流质量的关键因素。在此基础上,提出一种功率波动抑制与电流平衡协调控制策略,通过调节输出电流中的谐波分量大小来协调功率波动抑制水平与电流平衡正序程度。该功率控制方法不需要采用电压/电流正负序分离环节,也不需要陷波器或者滤波器,易于实现。最后,该功率控制方法的正确性通过仿真和实验进行验证。
The output power fluctuation and current quality of the grid-connected inverter under the unbalanced voltage environment are opposite to each other. First, the paper deduces the internal connection between the power oscillations and the current quality under unbalanced grid faults, the key factors that affect power fluctuation and current quality were analyzed. Then, a flexible power control strategy in stationary reference frame was proposed, and the power oscillations and the current quality can be controlled flexibly by changing the harmonic components in the output current. The proposed control strategy is convenient to realize without the need for positive/negative sequence extraction calculation, low pass filter or notch filter. Finally, the correctness of the proposed power control strategy is verified by simulation and experiment.
The output power fluctuation and current quality of the grid-connected inverter under the unbalanced voltage environment are opposite to each other. First, the paper deduces the internal connection between the power oscillations and the current quality under unbalanced grid faults, the key factors that affect power fluctuation and current quality were analyzed. Then, a flexible power control strategy in stationary reference frame was proposed, and the power oscillations and the current quality can be controlled flexibly by changing the harmonic components in the output current. The proposed control strategy is convenient to realize without the need for positive/negative sequence extraction calculation, low pass filter or notch filter. Finally, the correctness of the proposed power control strategy is verified by simulation and experiment.
引文
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[10]Song H S,Joo I W,Nam K.Source voltage sensorless estimation scheme for PWM rectifiers under unbalanced conditions[J].IEEE Transactions on Industrial Electronics,2003,50(6):1238-1245.
[11]Rodriguez P,Timbus A V,Teodorescu R,et al.Flexible active power control of distributed power generation systems during grid faults[J].IEEE Transactions on Industrial Electronics,2007,54(5):2583-2592.
[12]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(in Chinese).
[13]徐志英,徐爱国,谢少军.采用LCL滤波器的并网逆变器双闭环入网电流控制技术[J].中国电机工程学报,2009,29(27):36-41.Xu Zhiying,Xu Aiguo,Xie Shaojun.Dual-loop grid current control technique for grid-connected inverter using an LCL filter[J].Proceedings of the CSEE,2009,29(27):36-41(in Chinese).
[2]Suh Y,Lipo T A.Modeling and analysis of instantaneous active and reactive power for PWM AC/DC converter under generalized unbalanced network[J].IEEE Transactions on Power Delivery,2006,21(3):1530-1540.
[3]Etxeberria-Otadui I,Viscarret U,Caballero M,et al.New optimized PWM VSC control structures and strategies under unbalanced voltage transients[J].IEEE Transactions on Industrial Electronics,2007,54(5):2902-2914.
[4]全宇,年珩.不平衡及谐波电网下并网逆变器的谐振滑模控制技术[J].中国电机工程学报,2014,34(9):1345-1352.Quan Yu,Nian Heng.Resonance-based sliding mode control of grid connected inverters under unbalanced and harmonic grid voltages[J].Proceedings of the CSEE,2014,34(9):1345-1352(in Chinese).
[5]Hu Jiabing,He Yikang,Xu Lie,et al.Improved control of DFIG systems during network unbalance using PI-R current regulators[J].IEEE Transactions on Industrial Electronics,2009,56(2):439-451.
[6]吕志鹏,罗安,荣飞,等.电网电压不平衡条件下微网PQ控制策略研究[J].电力电子技术,2010,44(6):71-74.LüZhipeng,Luo An,Rong Fei,et al.Micro-grid PQ control strategy analysis under utility voltage imbalance[J].Power Electronics,2010,44(6):71-74(in Chinese).
[7]周洁,罗安,陈燕东,等.低压微电网多逆变器并联下的电压不平衡补偿方法[J].电网技术,2014,38(2):412-418.Zhou Jie,Luo An,Chen Yandong,et al.Voltage unbalance compensation for low-voltage microgrid with multi parallelly connected inverters[J].Power System Technology,2014,38(2):412-418(in Chinese).
[8]王逸超,罗安,金国彬.微网逆变器的不平衡电压补偿策略[J].中国电机工程学报,2015,35(19):4956-4964.Wang Yichao,Luo An,Jin Guobin.An unbalanced voltage compensation method for parallel inverters in microgrids[J].Proceedings of the CSEE,2015,35(19):4956-4964(in Chinese).
[9]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.
[10]Song H S,Joo I W,Nam K.Source voltage sensorless estimation scheme for PWM rectifiers under unbalanced conditions[J].IEEE Transactions on Industrial Electronics,2003,50(6):1238-1245.
[11]Rodriguez P,Timbus A V,Teodorescu R,et al.Flexible active power control of distributed power generation systems during grid faults[J].IEEE Transactions on Industrial Electronics,2007,54(5):2583-2592.
[12]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(in Chinese).
[13]徐志英,徐爱国,谢少军.采用LCL滤波器的并网逆变器双闭环入网电流控制技术[J].中国电机工程学报,2009,29(27):36-41.Xu Zhiying,Xu Aiguo,Xie Shaojun.Dual-loop grid current control technique for grid-connected inverter using an LCL filter[J].Proceedings of the CSEE,2009,29(27):36-41(in Chinese).