单相固态变压器逆变级的建模与控制
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摘要
为了实现固态变压器逆变级在不同调制方式的高性能控制要求,采用开关周期平均法和小信号扰动法,建立了单相固态变压器逆变级在双极性调制和单极性调制方式下的连续数学模型,并分别推导了内环电流对占空比的传递函数以及外环电压对电流的传递函数。明确了其数学模型和传递函数在单极性和双极性调制方式下是不一致的,避免了采用同一个数学模型所导致的控制性能不佳等问题。依据串级系统原理,设计了外环电压子系统和内环电感电流子系统,并提出了具体PI控制器参数设计方法。实验结果表明,建立的系统模型正确,且逆变级输出电压稳态精度高,响应速度快,电压总谐波畸变率低,表明控制策略设计合理。
In order to realize high performance control requirement for inverter stage of solid state transformer under different modulation mode,the small-signal dynamic models of single-phase inverter stage under bipolar and unipolar PWM modulation are built up based on the switching cycle average method and the small signal perturbation method.Consequently,the current to duty cycle transfer function and voltage to current transfer function are deduced respectively. It can be seen that the mathematical models and transfer functions are not consistent under bipolar and unipolar modulation mode,and it avoids the poor control performance problem when using the same mathematical mode. According to the cascade system principle,outer-loop voltage subsystem and inner-loop current subsystem are designed and parameter design methods of PI controller are proposed respectively. The experiment results show that the models established in the paper are correct. The output voltage of inverter stage has small stable error,high dynamic response and low total harmonic distortion,which means PI regulator and control strategy are practicable and reasonable.
In order to realize high performance control requirement for inverter stage of solid state transformer under different modulation mode,the small-signal dynamic models of single-phase inverter stage under bipolar and unipolar PWM modulation are built up based on the switching cycle average method and the small signal perturbation method.Consequently,the current to duty cycle transfer function and voltage to current transfer function are deduced respectively. It can be seen that the mathematical models and transfer functions are not consistent under bipolar and unipolar modulation mode,and it avoids the poor control performance problem when using the same mathematical mode. According to the cascade system principle,outer-loop voltage subsystem and inner-loop current subsystem are designed and parameter design methods of PI controller are proposed respectively. The experiment results show that the models established in the paper are correct. The output voltage of inverter stage has small stable error,high dynamic response and low total harmonic distortion,which means PI regulator and control strategy are practicable and reasonable.
引文
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[2]张明锐,刘金辉,金鑫.应用于智能微网的SVPWM固态变压器研究[J].电工技术学报,2012,(1):90-97.
[3]廖国虎,邱国跃,袁旭峰.电力电子变压器研究综述[J].电测与仪表,2014,51(16):5-10,36.Liao Guohu,Qiu Guoyue,Yuan Xufeng.Summary of the power electronic transformer[J].Electrical Measurement&Instrumentation,2014,51(16):5-10,36.
[4]凌晨,葛宝明,毕大强.配电网中的电力电子变压器研究[J].电力系统保护与控制,2012,(2):34-39.Ling Chen,Ge Baoming,Bi Daqiang.A power electronic transformer applied to distribution system[J].Power System Protection and Control,2012,(2):34-39.
[5]Z.Tiefu,W.Gangyao,Z.Jie,et al.Voltage and power balance control for a cascaded multilevel solid state transformer[C].2010Twenty-Fifth Annual IEEE in Applied Power Electronics Conference and Exposition(APEC),2010:761-767.
[6]S.Xu,W.Fei,R.Burgos,A.Q.Huang.Solid state transformer interfaced wind energy system with integrated active power transfer,reactive power compensation and voltage conversion functions[C].2012 IEEE in Energy Conversion Congress and Exposition(ECCE),2012:3140-3147.
[7]M.Ran,M.Chengxiong,L.Jiming,et al.Three-stage Solid State Transformer modeling through real time digital simulation with Controller Hardware-in-the-loop[C].7th International Power Electronics and Motion Control Conference(IPEMC),2012:1116-1119.
[8]J.Youyuan,L.Breazeale,R.Ayyanar,M.Xiaolin.Simplified Solid State Transformer modeling for Real Time Digital Simulator(RTDS)[C].2012 IEEE in Energy Conversion Congress and Exposition(ECCE),2012:1447-1452.
[9]C.J.Posada,J.M.Ramirez,R.E.Correa.Modeling and simulation of a solid state transformer for distribution systems[C].2012IEEE in Power and Energy Society General Meeting,2012:1-6.
[10]Z.Tiefu,Z.Jie,S.Bhattacharya,et al.An average model of solid state transformer for dynamic system simulation[C].Power&Energy Society General Meeting,2009:1-8.
[11]徐德鸿.电力电子系统建模与控制[M].北京:机械工业出版社,2010.