DC/DC与DC/AC级联变流器阻抗协调控制策略
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摘要
在back-to-back级联变流器系统中,前级子变流器的输出阻抗与后级子变流器的输入阻抗相互影响,如果系统参数设计不合理,将会恶化系统稳定性。该文提出了一种阻抗协调控制策略,将级联系统的前级子变流器和后级子变流器的低频阻抗均呈现为阻性阻抗,使得低频相移为0,从而提高back-to-back级联变流器系统的稳定性。基于双H桥DC/DC变流器和三相两电平逆变器级联拓扑结构,对所提控制策略与传统控制策略进行了比较。基于阻抗特性的稳定性判据显示,在低频范围内,所提控制策略可以促进前级功率源变流器和后级负载变流器面向中间直流母线侧呈现阻性阻抗,从而显著降低阻抗匹配作用产生的相移,有助于提高系统的稳定性。最后通过仿真和实验验证了所提出控制策略的有效性。
In back-to-back cascaded converter systems,the output impedance of front sub-converter will interact with the input impedance of the rear sub-converter. If the system parameters are not designed properly,it will worsen system stability.In this paper,the concept of impedance-coordination control is proposed. Low-frequency impedances of the front and rear sub-converters in the cascade system are modified to be resistive so that the low-frequency phase shift is zero,which may improve the stability of back-to-back cascaded converter system. Based on the cascaded topology of dual H-bridge DC/DC converters and three-phase two-level inverters,this paper compares the proposed control with conventional control strategies.The impedance-based stability evaluations show that,in low frequency range,the proposed control can promote both the front source converter and rear load converter to present resistive impedance towards dc link,then phase shift of the impedance interaction can be greatly reduced,which contributes to a better stability. Simulation and experiment verify the effectiveness of the proposed control strategy.
In back-to-back cascaded converter systems,the output impedance of front sub-converter will interact with the input impedance of the rear sub-converter. If the system parameters are not designed properly,it will worsen system stability.In this paper,the concept of impedance-coordination control is proposed. Low-frequency impedances of the front and rear sub-converters in the cascade system are modified to be resistive so that the low-frequency phase shift is zero,which may improve the stability of back-to-back cascaded converter system. Based on the cascaded topology of dual H-bridge DC/DC converters and three-phase two-level inverters,this paper compares the proposed control with conventional control strategies.The impedance-based stability evaluations show that,in low frequency range,the proposed control can promote both the front source converter and rear load converter to present resistive impedance towards dc link,then phase shift of the impedance interaction can be greatly reduced,which contributes to a better stability. Simulation and experiment verify the effectiveness of the proposed control strategy.
引文
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[23]CHANG X Y,LI Y L,LI X,et al.An active damping method based on a supercapacitor energy storage system to overcome the destabilizing effect of instantaneous constant power loads in dc microgrids[J].IEEE Transactions on Energy Conversion,2017,32(1):36-47.
[24]GUO L,ZHANG S H,LI X L,et al.Stability analysis and damping enhancement based on frequency-dependent virtual impedance for DC microgrids[J].IEEE Journal of Emerging and Selected Topics in Power Electronics,2017,5(1):338-350.
[2]WANG Y,WANG X,CHEN Z,et al.Distributed optimal control of reactive power and voltage in islanded microgrids[J].IEEETransactions on Industry Application,2017,53(1):340-349.
[3]郭雅娟,陈锦铭,何红玉,等.交直流混合微电网接入分布式新能源的关键技术研究综述[J].电力建设,2017,38(3):9-18.GUO Yajuan,CHEN Jinming,HE Hongyu,et al.A review on AC/DC hybrid microgrid key technology containing distributed new energy[J].Electrci Power Construction,2017,38(3):9-18.
[4]何湘宁,石巍,李武华,等.基于大数据的大容量电力电子系统可靠性研究[J].中国电机工程学报,2017,37(1):209-221.HE Xiangning,SHI Wei,LI Wuhua,et al.Reliability enhancement of power electronics systems by big data science[J].Proceedings of the CSEE,2017,37(1):209-221.
[5]Middlebrook R D D.Input filter considerations in design and application of switching regulators[C]//IEEE Industry Applications Society.IEEE,1979:366-382.
[6]POLSTER S,RENNER H.Voltage stability monitoring methods for distribution grids using theThevenin impedance[C]//24th International Conference&Exhibition on Electricity Distribution(CIRED).CIRED,2017:1535-1539.
[7]KHALIGH A.Realization of parasitics in stability of DC-DCconverters loaded by constant power loads in advanced multiconverter automotive systems[J].IEEE Transactions on Industrial Electronics,2008,55(6):2295-2305.
[8]SUN J.Impedance-based stability criterion for grid-connected inverters[J].IEEE Transactions on Power Electronics,2011,26(11):3075-3078.
[9]CHEN B,PIN G,PARISINI W M N,et al.A fast-convergent modulation integral observer for online detection of the fundamental and harmonics in grid-connected power electronics systems[J].IEEETransactions on Power Electronics,2017,32(4):2596-2607.
[10]JUSOH A B.The instability effect of constant power loads[C]//Power and Energy Conference,2004.Kuala Lumpur,Malaysia:IEEE,2005:175-179.
[11]RADWAN A A A,MOHAMED Y A I.Analysis and activeimpedancebased stabilization of voltage-source-rectifier loads in grid-connected and isolated micorgrid applications[J].IEEETransactions on Sustainable Energy,2013,4(3):563-576.
[12]WEAVER W W,KREIN P T.Optimal geometric control of power buffers[J].IEEE Transactions on Power Electronics,2009,24(5):1248-1258.
[13]Sopapirm T,Areerak K,Bozhko S,et al.Adaptive stabilization of uncontrolled rectifier based AC-DC power systems feeding constant power loadsin[J].IEEE Transactions on Power Electronics,2017,48(5):1248-1258.
[14]RAHIMI A M,EMADI A.Active damping in DC/DC power electronic converters:A novel method to overcome the problems of constant power loads[J].IEEE Transactions on Industrial Electronics,2009,56(5):1428-1439.
[15]GENG H,XU D,WU B,et al.Active damping for PMSG-based WECS with DC-link current estimation[J].IEEE Transactions on Industrial Electronics,2011,58(4):1110-1119.
[16]TIAN Y J,CHEN Z,DENG F J,et al.Active power and DCvoltage coordinative control for cascaded DC-AC converter with bidirectional power application[J].IEEE Transactions on Power Electronics,2015,30(10):5911-5925.
[17]PIDAPARTHY S K K,CHOI B,KIM Y.A load impedance specification of dc power systems for desired dc link dynamics and reduced conservativeness[C]//IEEE 18th Workshop on Control and Modeling for Power Electronics(COMPEL).IEEE,2017:1-6.
[18]KRISHNAMURTHY H,AYYANAR R.Stability analysis of cascaded converters for bidirectional power flow application[C]//Telecommunications Energy Conference,2008.San Diego,USA:IEEE,2008:1-8.
[19]ROGGIA L,SCHUCH L,BAGGIO J,et al,Integrated full-bridgeforward DC-DC converter for a residential microgrid application[J].IEEE Transactions on Power Electronics,2013,28(4):1728-1740.
[20]KRISME F,KOLAR J W.Efficiency-optimized high-current dual active bridge converter for automotive applications[J].IEEETransactions on Power Electronics,2012,59(7):2745-2760.
[21]QIN H,KIMBALL J W.Closed-loop control of DC-DC dualactivebridge converters driving single-phase inverters[J].IEEETransactions on Power Electronics,2014,29(2):1006-1017.
[22]TIAN Y J,DENG F J,CHEN Z,et al.Impedance interaction modeling and analysis for bidirectional cascaded converters[C]//Power Electronics and ECCE Asia(ICPE-ECCE Asia),2015 9th International Conference on.Asia,Seoul,Korea:IEEE,2015:2064-2071.
[23]CHANG X Y,LI Y L,LI X,et al.An active damping method based on a supercapacitor energy storage system to overcome the destabilizing effect of instantaneous constant power loads in dc microgrids[J].IEEE Transactions on Energy Conversion,2017,32(1):36-47.
[24]GUO L,ZHANG S H,LI X L,et al.Stability analysis and damping enhancement based on frequency-dependent virtual impedance for DC microgrids[J].IEEE Journal of Emerging and Selected Topics in Power Electronics,2017,5(1):338-350.