不同负载条件下光伏接口MPPT变换器的小信号建模及实验验证
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摘要
在分布式光伏发电系统中,光伏电池一般通过DC-DC变换器与后级相连,以实现输出最大功率跟踪(MPPT).由于光伏电池的本质电流源特性,使得输入电压反馈控制光伏接口MPPT变换器为电流源变换器,会呈现出与常见电压源变换器截然不同的动态特性.以前置电容Boost变换器为研究对象,重点探讨电流源MPPT变换器的频率响应特性.首先,建立了开环和输入电压闭环两种控制方式下系统的小信号模型,并揭示不同负载类型对于系统频率响应的影响;其次,对MPPT变换器的端口阻抗进行了建模分析,指出影响闭环输入、输出阻抗特性的重要因素,为接口电路的后续稳定性设计提供理论指导;最后,搭建实验室电路样机,通过频域和时域测试结果验证了理论分析的正确性.
In distributed photovoltaic( PV) generation systems,PV cells are in general connected to downstream power stage through interfacing DC-DC converters to fulfill maximum power point tracking( MPPT). Due to inherent currentsource nature of the PV cell, the input voltage controlled PV-interfacing MPPT converter will become a current-fed( CF) converter which shows distinct dynamic features from those of the usual voltage-fed( VF) converters. In this regard, taking the Boost converter with an input capacitor as the case of study, this paper aims to investigate frequency responses of the CF MPPT converter. Firstly, small-signal models of the control system under both open-loop and input voltage controlled closedloop are derived, and then the influences of load type on the system frequency responses are revealed. Secondly, the terminal impedances of the MPPT converter are modeled and analyzed, and the important factors affect the closed-loop input and output impedances are pointed out,which will provide theoretical guide for future stability design of the interfacing circuit. Finally,a laboratory prototype is built, and the analyses are verified by test results in both time-and frequency-domains.
In distributed photovoltaic( PV) generation systems,PV cells are in general connected to downstream power stage through interfacing DC-DC converters to fulfill maximum power point tracking( MPPT). Due to inherent currentsource nature of the PV cell, the input voltage controlled PV-interfacing MPPT converter will become a current-fed( CF) converter which shows distinct dynamic features from those of the usual voltage-fed( VF) converters. In this regard, taking the Boost converter with an input capacitor as the case of study, this paper aims to investigate frequency responses of the CF MPPT converter. Firstly, small-signal models of the control system under both open-loop and input voltage controlled closedloop are derived, and then the influences of load type on the system frequency responses are revealed. Secondly, the terminal impedances of the MPPT converter are modeled and analyzed, and the important factors affect the closed-loop input and output impedances are pointed out,which will provide theoretical guide for future stability design of the interfacing circuit. Finally,a laboratory prototype is built, and the analyses are verified by test results in both time-and frequency-domains.
引文
[1]宁勇,戴瑜兴,王镇道,等.不同MPPT架构光伏系统发电效率的比较研究[J].电子学报,2016,44(9):2134-2140.Y Ning,Y Dai,Z Wang,et al. A comparative study of cen-tral and grouped and distributed M PPT architectures forpow er generation efficiency of photovoltaic system[J]. Ac-ta Electronica Sinica,2016,44(9):2134-2140.(in Chi-nese)
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[9] Messo T,Jokipii J,Suntio T. Steady-state and dynamicproperties of boost-pow er-stage converter in photovoltaicapplications[A]. IEEE International Symposium on Pow erElectronics for Distributed Generation Systems(PEDG)[C]. Aalborg,Denmark,2012. 34-40.
[10] Hsu C T,Li P,Sheng S,et al. A maximum power pointtracking method for PV systems supplying a periodic non-linear load[A]. The Fifth Annual IEEE Energy Conver-sion Congress and Exposition(ECCE)[C]. Raleigh,NC,USA,2013. 2771-2777.
[11]Dong J,Zhang C J,Li Y B. Comparison of duty ratio per-turbation&observation and reference voltage perturbation&observation methods applied in M PPT[A]. 7th IEEEInternational Pow er Electronics and M otion Control Con-ference(IPEM C)[C]. Harbin,China,2012. 1358-1362.
[12]Dragicevi'c T,Lu X,Vasquez J C,et al. DC microgrids-Part I:A review of control strategies and stabilization tech-niques[J]. IEEE Transactions on Pow er Electronics,2016,31(7):4876-4891.
[13]Li A,Zhang D. Necessary and sufficient stability criterionand new forbidden region for load impedance Specification[J]. Chinese Journal of Electronics,2014,3(03):628-634.
[14]Suntio T,Viinamaki J,Jokipii J,et al. Effect of input andoutput terminal sources on dynamic behavior of sw itched-mode converters[A]. IEEE International Pow er Electron-ics Conference(IPEC)[C]. Hiroshima,Japan,2014. 2240-2246.
[15]Villalva M G,De Siqueira T G,Ruppert E. Voltage regu-lation of photovoltaic arrays:small-signal analysis andcontrol design[J]. IET Pow er Electronics,2010,3(6):869-880.
[16]Viinamaki J,Jokipii J,Messo T,et al. Comprehensive dy-namic analysis of photovoltaic generator interfacing DC-DC boost pow er stage[J]. IET Renew able Pow er Genera-tion,2014,9(4):306-314.
[17]El Aroudi A,Zhioua M,Al-Numay M,et al. Stability A-nalysis of a Boost Converter w ith an M PPT Controller forPhotovoltaic Applications[M]. Lecture Notes in ElectricalEngineering,Springer,Cham,2016. 483-491.
[18] Snyman D B,Enslin J R. Simplified maximum powerpoint controller for PV installations[A]. Tw enty-ThirdIEEE Photovoltaic Specialists Conference[C]. Louisville,KY,1993. 1240-1245.
[19] Venturini R P,Scarpa V R,Spiazzi G,et al. Analysis oflimit cycle oscillations in maximum pow er point trackingalgorithms[A]. IEEE Pow er Electronics Specialists Con-ference(PESC)[C]. Rhodes,Greece,2008. 378-384.
[20] Maki A,Valkealahti S,Suntio T. Dynamic terminal char-acteristics of a photovoltaic generator[A]. 14th IEEE In-ternational Pow er Electronics and M otion Control Confer-ence(EPE/PEM C)[C]. Ohrid,Republic of M acedonia,2010. 76-80.
[21]Erickson R W,Maksimovic D. Fundamentals of power e-lectronics[M]. Springer Science&Business M edia,2007.
[22]Zhang X,Ruan X,Chi K T. Impedance-based local stabili-ty criterion for dc distributed pow er systems[J]. IEEETransactions on Circuits and Systems I:Regular Papers,2015,62(3):916-925.
[23] Ahmadi R,Paschedag D,Ferdowsi M. Closed-loop inputand output impedances of DC-DC sw itching convertersoperating in voltage and current mode control[A]. 36thAnnual IEEE Conference on Industrial Electronics Society(IECON)[C]. Glendale,Arizona,USA,2010. 2311-2316.
[2] Aguillon-Garcia J,Banuelos-Sanchez P. High-efficiencyDC-DC converter for large input-voltage fluctuations insolar applications[J]. Chinese Journal of Electronics,2015,24(3):502-507.
[3]Suntio T,Leppaaho J,Huusari J,et al. Issues on solar-gen-erator interfacing w ith current-fed M PP-tracking converters[J]. IEEE Transactions on Power Electronics,2010,25(9):2409-2419.
[4]秦岭,谢少军,杨晨.光伏电池与前置电容式电流型M PPT变换器的接口稳定性研究[J].电工技术学报,2013,28(5):135-141.L Qin,S Xie,C Yang. The interfacing stability of photovol-taic cells and current-fed M PPT converter[J]. Transactionsof China Electro technical Society,2013,28(5):135-141.(in Chinese)
[5] Capel A,Marpinard J C,Jalade J,et al. Current fed andvoltage fed sw itching DC/DC converters-Steady state anddynamic models their applications in space technology[A]. The Fifth IEEE Telecommunications Energy Confer-ence(INTELEC)[C]. Tokyo,Japan,1983. 421-430.
[6]Nousiainen L,Puukko J,Maki A,et al. Photovoltaic genera-tor as an input source for pow er electronic converters[J].IEEE Transactions on Pow er Electronics,2013,28(6):3028-3038.
[7] Leppaaho J,Suntio T. Solar-generator-interfacing with acurrent-fed superbuck converter implemented by duality-transformation methods[A]. IEEE International Pow er E-lectronics Conference(IPEC)[C]. Sapporo,Japan,2010.680-687.
[8] Leppaaho J,Nousiainen L,Puukko J,et al. Implementingcurrent-fed converters by adding an input capacitor at theinput of voltage-fed converter for interfacing solar generator[A]. 14th IEEE International Power Electronics and Mo-tion Control Conference(EPE/PEM C)[C]. Ohrid,Repub-lic of M acedonia,2010. 81-88.
[9] Messo T,Jokipii J,Suntio T. Steady-state and dynamicproperties of boost-pow er-stage converter in photovoltaicapplications[A]. IEEE International Symposium on Pow erElectronics for Distributed Generation Systems(PEDG)[C]. Aalborg,Denmark,2012. 34-40.
[10] Hsu C T,Li P,Sheng S,et al. A maximum power pointtracking method for PV systems supplying a periodic non-linear load[A]. The Fifth Annual IEEE Energy Conver-sion Congress and Exposition(ECCE)[C]. Raleigh,NC,USA,2013. 2771-2777.
[11]Dong J,Zhang C J,Li Y B. Comparison of duty ratio per-turbation&observation and reference voltage perturbation&observation methods applied in M PPT[A]. 7th IEEEInternational Pow er Electronics and M otion Control Con-ference(IPEM C)[C]. Harbin,China,2012. 1358-1362.
[12]Dragicevi'c T,Lu X,Vasquez J C,et al. DC microgrids-Part I:A review of control strategies and stabilization tech-niques[J]. IEEE Transactions on Pow er Electronics,2016,31(7):4876-4891.
[13]Li A,Zhang D. Necessary and sufficient stability criterionand new forbidden region for load impedance Specification[J]. Chinese Journal of Electronics,2014,3(03):628-634.
[14]Suntio T,Viinamaki J,Jokipii J,et al. Effect of input andoutput terminal sources on dynamic behavior of sw itched-mode converters[A]. IEEE International Pow er Electron-ics Conference(IPEC)[C]. Hiroshima,Japan,2014. 2240-2246.
[15]Villalva M G,De Siqueira T G,Ruppert E. Voltage regu-lation of photovoltaic arrays:small-signal analysis andcontrol design[J]. IET Pow er Electronics,2010,3(6):869-880.
[16]Viinamaki J,Jokipii J,Messo T,et al. Comprehensive dy-namic analysis of photovoltaic generator interfacing DC-DC boost pow er stage[J]. IET Renew able Pow er Genera-tion,2014,9(4):306-314.
[17]El Aroudi A,Zhioua M,Al-Numay M,et al. Stability A-nalysis of a Boost Converter w ith an M PPT Controller forPhotovoltaic Applications[M]. Lecture Notes in ElectricalEngineering,Springer,Cham,2016. 483-491.
[18] Snyman D B,Enslin J R. Simplified maximum powerpoint controller for PV installations[A]. Tw enty-ThirdIEEE Photovoltaic Specialists Conference[C]. Louisville,KY,1993. 1240-1245.
[19] Venturini R P,Scarpa V R,Spiazzi G,et al. Analysis oflimit cycle oscillations in maximum pow er point trackingalgorithms[A]. IEEE Pow er Electronics Specialists Con-ference(PESC)[C]. Rhodes,Greece,2008. 378-384.
[20] Maki A,Valkealahti S,Suntio T. Dynamic terminal char-acteristics of a photovoltaic generator[A]. 14th IEEE In-ternational Pow er Electronics and M otion Control Confer-ence(EPE/PEM C)[C]. Ohrid,Republic of M acedonia,2010. 76-80.
[21]Erickson R W,Maksimovic D. Fundamentals of power e-lectronics[M]. Springer Science&Business M edia,2007.
[22]Zhang X,Ruan X,Chi K T. Impedance-based local stabili-ty criterion for dc distributed pow er systems[J]. IEEETransactions on Circuits and Systems I:Regular Papers,2015,62(3):916-925.
[23] Ahmadi R,Paschedag D,Ferdowsi M. Closed-loop inputand output impedances of DC-DC sw itching convertersoperating in voltage and current mode control[A]. 36thAnnual IEEE Conference on Industrial Electronics Society(IECON)[C]. Glendale,Arizona,USA,2010. 2311-2316.