三电平光伏并网逆变器的控制策略研究
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摘要
随着全球能源危机和环境污染的日益严重,太阳能的开发和利用受到世界各国的普遍关注。光伏并网发电是太阳能光伏利用的主要发展趋势,必将得到快速的发展。在此背景下,本文对光伏并网逆变器的拓扑结构和并网控制方案进行了重点研究。
传统的两电平并网逆变器开关损耗大,直流电压利用低,输出电流谐波高,无法实现高压高质量的并网要求。本文采用了三电平NPC光伏并网逆变主电路,分析了其工作原理,着重研究了空间矢量PWM调制方法。针对三电平逆变器直流侧中点电位不平衡问题,从空间矢量PWM调制方法的角度出发,本文采用了一种只需检测各相电流和中点电压波动的方向,动态调整正负小矢量作用时间实现中点电位平衡控制方法。仿真结果验证了方法的有效性。
建立了三电平并网逆变器在静止ABC坐标系下的数学模型,通过坐标变换,推导了同步旋转dq坐标系下的数学模型。为了实现并网电流的跟踪控制,本文在旋转dq坐标系下提出了电流重复预测无差拍控制方案。构造状态观测器,对逆变器下一拍输出电流进行预报,补偿数字控制系统存在时间上的延时;同时,构造重复预测观测器,对下一时刻指令电流进行预测,在相同的采样频率下提供更为精确的并网电流预测值。整个方案消除了延时对控制系统的影响,实现无静差跟踪指令电流,动态响应快,降低了并网输出电流畸变率,改善了系统的控制性能。仿真结果表明了该方案的有效性和可行性。
With the situation of global energy crisis and environment pollution becoming more and more serious, the whole world pays more attention on exploiting and utilizing the solar energy. The PV grid-connected system is the main utilization of the solar energy, so it will be developed rapidly. Under this background, the topology and control strategies of the PV grid-connected inverter are researched deeply in this paper.
Traditional two-level inverter has disadvantages of large switching loss, low DC voltage utilization rate and high output current harmonics, so it couldn't fulfill high quality of the gird-connect system. Three-level NPC inverter is introduced for the gird-connect system in this paper. SVPWM modulation scheme of Three-level inverter is introduced in detail. Neutral-point potential unbalance is an inherent problem of three-level NPC inverter, so a neutral-point control method which is based on directions of the three-phase output current and the neutral-point voltage to regulate the action times of positive and negative small vector is adopted. Availability of the method is testified by the simulation results.
The mathematic model in ABC three-phase static coordinate of the three-level inverter is set up. Using coordinate transformation, the mathematic model in dq two-phase rotating coordinate is established. To actualize the gird-connected current tracking control, this paper presents a deadbeat repetitive predictive current control scheme in dq two-phase rotating coordinate. The state observer is designed to obtain the predictive output current value and compensate the time delay of digital control system. At the same time, the current repetitive predictor is adopted to achieve better prediction of the grid-connected current with the same sampling frequency. This scheme has merits of reducing output current harmonics, improving the effect of time delay and the overall performance of the system. The feasibility and correctness of the proposed control strategy are verified by simulation results.
传统的两电平并网逆变器开关损耗大,直流电压利用低,输出电流谐波高,无法实现高压高质量的并网要求。本文采用了三电平NPC光伏并网逆变主电路,分析了其工作原理,着重研究了空间矢量PWM调制方法。针对三电平逆变器直流侧中点电位不平衡问题,从空间矢量PWM调制方法的角度出发,本文采用了一种只需检测各相电流和中点电压波动的方向,动态调整正负小矢量作用时间实现中点电位平衡控制方法。仿真结果验证了方法的有效性。
建立了三电平并网逆变器在静止ABC坐标系下的数学模型,通过坐标变换,推导了同步旋转dq坐标系下的数学模型。为了实现并网电流的跟踪控制,本文在旋转dq坐标系下提出了电流重复预测无差拍控制方案。构造状态观测器,对逆变器下一拍输出电流进行预报,补偿数字控制系统存在时间上的延时;同时,构造重复预测观测器,对下一时刻指令电流进行预测,在相同的采样频率下提供更为精确的并网电流预测值。整个方案消除了延时对控制系统的影响,实现无静差跟踪指令电流,动态响应快,降低了并网输出电流畸变率,改善了系统的控制性能。仿真结果表明了该方案的有效性和可行性。
With the situation of global energy crisis and environment pollution becoming more and more serious, the whole world pays more attention on exploiting and utilizing the solar energy. The PV grid-connected system is the main utilization of the solar energy, so it will be developed rapidly. Under this background, the topology and control strategies of the PV grid-connected inverter are researched deeply in this paper.
Traditional two-level inverter has disadvantages of large switching loss, low DC voltage utilization rate and high output current harmonics, so it couldn't fulfill high quality of the gird-connect system. Three-level NPC inverter is introduced for the gird-connect system in this paper. SVPWM modulation scheme of Three-level inverter is introduced in detail. Neutral-point potential unbalance is an inherent problem of three-level NPC inverter, so a neutral-point control method which is based on directions of the three-phase output current and the neutral-point voltage to regulate the action times of positive and negative small vector is adopted. Availability of the method is testified by the simulation results.
The mathematic model in ABC three-phase static coordinate of the three-level inverter is set up. Using coordinate transformation, the mathematic model in dq two-phase rotating coordinate is established. To actualize the gird-connected current tracking control, this paper presents a deadbeat repetitive predictive current control scheme in dq two-phase rotating coordinate. The state observer is designed to obtain the predictive output current value and compensate the time delay of digital control system. At the same time, the current repetitive predictor is adopted to achieve better prediction of the grid-connected current with the same sampling frequency. This scheme has merits of reducing output current harmonics, improving the effect of time delay and the overall performance of the system. The feasibility and correctness of the proposed control strategy are verified by simulation results.
引文
[1]王长贵.新能源和可再生能源的现状和展望[C].太阳能光伏产业发展论坛论文集,2003,9:4-9.
[2]赵玉文.21世纪我国光伏产业发展战略思考.合肥工业大学讲座,2002.
[3]赵玉文.太阳能光伏技术的发展概况[C].第五届全国光伏技术学术研讨会论文集,1998.
[4]Bnner JP,Kazmerski L.Photovoltaics gaining greater visebility.Spectrum,IEEE.1999,36(9):34-42.
[5]林安中,王斯成.国内外太阳电池和光伏发电的进展和前景[J].太阳能学报增刊,1999:68-74.
[6]梁有伟,胡志坚,陈允平.分布式发电及其在电力系统中的应用研究综述[J].电网技术,2003(27):71-75.
[7]Green MA.Third generation Photo voltaics:comparative evaluation of advanced solar conversion options.Photovoltaic Specialists Conference,Conference Record of the Twellty-Ninth IEEE.2002:1330-1334.
[8]董密.太阳能光伏并网发电系统的优化设计与控制策略研究[D].中南大学博士学位论文,2007,5.
[9]郭廷伟.太阳能的利用和前景[M].北京:科学普及出版社,1984.
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[12]黄讯.我国光伏发电的现状及市场展望[J].中国环保产业,2003(5):20-21.
[13]赵玉文.我国太阳能光伏产业发展形式和思考[J].世界科技研究与发展,200325(4):31-38.
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[16]焦在强.单级式并网型光伏发电系统用逆变器的研究[D].中国科学院研究生院硕士学位论文,北京,2004.
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[18]张超.光伏并网发电系统MPPT及孤岛检测新技术的研究[D].浙江大学博士论文,2006.
[19]IEEE Recommended Practice for Utility Interface of Photovoltaic(PV)Systems,2000.
[20]赵玉文.我国太阳能光伏产业发展形势和思考[J].世界科技研究与发展2003.25(4):31-38.
[21]赵宏,潘俊民.基于Boost电路的光伏电池最大功率点跟踪系统[J].电力电子技术.2004.38(3):55-57.
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[23]Bin wu.大功率逆变器及交流传动[M].北京:机械工业出版社,2007,8.
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[25]Tae Yeop Kim,et al.A Novel Maximum Power Point Tracking Control for Photovoltaic Power System Under Rapidly Changing Solar Radiation.IEEE International Symposium on Industrial Electronics,2001,2:1011-1014.
[26]Eftichios Koutroulisal.Development of a Micro-controller Based Photovoltaic Maximum Power Point Tracking Control System..IEEE Trans Power Electronics,2001,16(1):46-54.
[27]K.K.Tse,et al.A Comparative Study of Maximum-power-point Tracker for Photovoltaic Panel Using Switching-Frequency Modulation Scheme.IEEE Trans and Electron,2004,51(2):410-418.
[28]陈桂兰,孙晓等.光伏发电系统最大功率点跟踪控制[J].电子技术应用,2001,27(8):33-35.
[29]Nobuyoshi Motuh,et al.Prediction-data-based maximum power point tracking method for photovoltaic power generation systems.PESC Record-IEEE Annual Power Electronics Specialists Conference,2002,3:1489-1494.
[30]Bogdan M.Wilamowski,Xiangli Li.Fuzzy system based maximum power point tracking for PV system.IECON Proceedings,2002,4:280-3284.
[31]赵宏,潘俊民.基于Boost电路的光伏电池最大功率点跟踪系统[J].电力电子技术,2004(6):55-57.
[32]Khaehintung N,Sirisuk P,Implementation of maximum power point tracking using fuzzy logic controller for solar-powered light-flasher applications.Midwest Symp Circuits Syst,2004,3:171-174.
[33]吴守滚.电气传动的脉宽调制控制技术[M].机械工业出版社,1999:173-175.
[34]CLk.1.ee,S.YR.Hui,H.Shu-Hung Chung.Randomized Voltage Vector Switching Scheme for Three-Level Power Inverters[C].IEEE Trans.on Power Electronics,2002,vol.17,No.1,2002:92-100.
[35]刘凤君.现代逆变技术及其应用[M].电子工业出版社,2006:1-5.
[36]N.Celanovic,D.Voroyevich.A comprehensive study of neutral-point voltage balancing problem in three-level neutral-point-clamped voltage source PWM inverters.IEEE Trans.On Power Electronics,2000,15(2):242-249.
[37]王展,邹云屏,林磊.一种三电平逆变器中点平衡的控制方法[J].电源技术学报,2004,2(4):287-291.
[38]王广柱.二极管箝位型多电平逆变器直流侧电容电压不平衡机理的研究[J].中国电机工程学报,2002,22(12):111-117.
[39]王兆安,黄俊.电力电子技术[M].北京:机械工业出版社,2004,2.
[40]张兴,张崇巍,曹仁贤.光伏并网逆变器非线性控制策略的研究[J].太阳能学报,2002(23):770-773.
[41]林磊.三电平逆变器控制系统研究.华中科技大学硕士学位论文.武汉,华中科技大学图书馆,2004.
[42]吴浩伟,段善旭.基于重复和PI控制的中频逆变器符合控制方案[J].电力电子技术,2006,40(4):38-40.
[43]H J Jiang.DSP based implementation of a digitally controlled single phase PWM inverter for UPS,IEEE-INTELEC99,1999:221-224.
[44]吴杰,茆美琴.基于重复控制算法的光伏并网逆变的研究[J].电源技术,2005.
[45]韩郁,詹长江,赵良炳,等.三电平并联型电能质量调节器的控制技术研究[J].清华大学学报,2000,40(3):40-43.
[46]张凯.基于重复控制原理的CVCF-PWM逆变器波形控制技术研究.华中理工大学博士学位论文.武汉,华中理工大学,2000.
[47]李庚银,陈志业,杨以涵,等.有源补偿器直流侧电压控制系统[J].华北电力大学学报,1997,24(3):1-7.
[48]N.Celanovic,D.Voroyevich.A comprehensive study of neutral-point voltagebalancing problem in three-level neutral-point-clamped voltage source PWM inverters.IEEE Trans.on Power Electronics,2000,15(2):242-249.
[49]庄淑瑾,孙玉坤,任明炜,等.静止无功发生器的预测电流控制方法[J].电力自动化设备,2008,28(11):53-56.
[50]Huy L H,Slimani K,Viarouge P.Analysis and implementation of a real-time predictive current controller for permanent-magnet synchronous servo drives[J].IEEE Transactions on Industrial Electronics,1994,41(1):110-117.
[51]Mossoba J,Lehn P.A controller architecture for high bandwidth active power filters[J].IEEE Transactions on Power Electronics,2003,18(1):317-325.
[52]Mohamed Y A R I,El-Saadany E F.An improved deadbeat current control scheme with a novel adaptive self-tuning load model for a three-phase PWM voltage-source inverter[J].IEEE Transactions on Industrial Electronics,2007,54(2):749-759.
[2]赵玉文.21世纪我国光伏产业发展战略思考.合肥工业大学讲座,2002.
[3]赵玉文.太阳能光伏技术的发展概况[C].第五届全国光伏技术学术研讨会论文集,1998.
[4]Bnner JP,Kazmerski L.Photovoltaics gaining greater visebility.Spectrum,IEEE.1999,36(9):34-42.
[5]林安中,王斯成.国内外太阳电池和光伏发电的进展和前景[J].太阳能学报增刊,1999:68-74.
[6]梁有伟,胡志坚,陈允平.分布式发电及其在电力系统中的应用研究综述[J].电网技术,2003(27):71-75.
[7]Green MA.Third generation Photo voltaics:comparative evaluation of advanced solar conversion options.Photovoltaic Specialists Conference,Conference Record of the Twellty-Ninth IEEE.2002:1330-1334.
[8]董密.太阳能光伏并网发电系统的优化设计与控制策略研究[D].中南大学博士学位论文,2007,5.
[9]郭廷伟.太阳能的利用和前景[M].北京:科学普及出版社,1984.
[10]薛钰芝,张力,林纪宁.太阳能光伏技术的研究与发展[J].大连铁道学院学报,2003,24(4):71-74.
[11]张扬,高辉.太阳能利用与环境可持续发展是统一框架下的系统工程----美洲百万太阳能屋顶计划启示[J].新能源,2000,22(9),51.
[12]黄讯.我国光伏发电的现状及市场展望[J].中国环保产业,2003(5):20-21.
[13]赵玉文.我国太阳能光伏产业发展形式和思考[J].世界科技研究与发展,200325(4):31-38.
[14]Ball GJ,Hudson P,M,Behnke MR.Recent application and performance of large,grid-connected commercial PV systems.Photovoltaic Specialists Conference,2002 Conference Record of the Twenty-Ninth IEEE.2002:1710-1713.
[15]冯垛生.太阳能发电原理与应用[M].北京:人民邮电出版社,2007.95-98.
[16]焦在强.单级式并网型光伏发电系统用逆变器的研究[D].中国科学院研究生院硕士学位论文,北京,2004.
[17]董密,罗安.光伏并网发电系统中逆变器的设计与控制方法[J].电力系统自动化,2006,30(20):97-102.
[18]张超.光伏并网发电系统MPPT及孤岛检测新技术的研究[D].浙江大学博士论文,2006.
[19]IEEE Recommended Practice for Utility Interface of Photovoltaic(PV)Systems,2000.
[20]赵玉文.我国太阳能光伏产业发展形势和思考[J].世界科技研究与发展2003.25(4):31-38.
[21]赵宏,潘俊民.基于Boost电路的光伏电池最大功率点跟踪系统[J].电力电子技术.2004.38(3):55-57.
[22]李安定.太阳能光伏发电系统工程[M].北京:北京工业大学出版社,2001.
[23]Bin wu.大功率逆变器及交流传动[M].北京:机械工业出版社,2007,8.
[24]苏建徽等.硅太阳电池工程用数学模型[J].太阳能学报,2001(22):42-49.
[25]Tae Yeop Kim,et al.A Novel Maximum Power Point Tracking Control for Photovoltaic Power System Under Rapidly Changing Solar Radiation.IEEE International Symposium on Industrial Electronics,2001,2:1011-1014.
[26]Eftichios Koutroulisal.Development of a Micro-controller Based Photovoltaic Maximum Power Point Tracking Control System..IEEE Trans Power Electronics,2001,16(1):46-54.
[27]K.K.Tse,et al.A Comparative Study of Maximum-power-point Tracker for Photovoltaic Panel Using Switching-Frequency Modulation Scheme.IEEE Trans and Electron,2004,51(2):410-418.
[28]陈桂兰,孙晓等.光伏发电系统最大功率点跟踪控制[J].电子技术应用,2001,27(8):33-35.
[29]Nobuyoshi Motuh,et al.Prediction-data-based maximum power point tracking method for photovoltaic power generation systems.PESC Record-IEEE Annual Power Electronics Specialists Conference,2002,3:1489-1494.
[30]Bogdan M.Wilamowski,Xiangli Li.Fuzzy system based maximum power point tracking for PV system.IECON Proceedings,2002,4:280-3284.
[31]赵宏,潘俊民.基于Boost电路的光伏电池最大功率点跟踪系统[J].电力电子技术,2004(6):55-57.
[32]Khaehintung N,Sirisuk P,Implementation of maximum power point tracking using fuzzy logic controller for solar-powered light-flasher applications.Midwest Symp Circuits Syst,2004,3:171-174.
[33]吴守滚.电气传动的脉宽调制控制技术[M].机械工业出版社,1999:173-175.
[34]CLk.1.ee,S.YR.Hui,H.Shu-Hung Chung.Randomized Voltage Vector Switching Scheme for Three-Level Power Inverters[C].IEEE Trans.on Power Electronics,2002,vol.17,No.1,2002:92-100.
[35]刘凤君.现代逆变技术及其应用[M].电子工业出版社,2006:1-5.
[36]N.Celanovic,D.Voroyevich.A comprehensive study of neutral-point voltage balancing problem in three-level neutral-point-clamped voltage source PWM inverters.IEEE Trans.On Power Electronics,2000,15(2):242-249.
[37]王展,邹云屏,林磊.一种三电平逆变器中点平衡的控制方法[J].电源技术学报,2004,2(4):287-291.
[38]王广柱.二极管箝位型多电平逆变器直流侧电容电压不平衡机理的研究[J].中国电机工程学报,2002,22(12):111-117.
[39]王兆安,黄俊.电力电子技术[M].北京:机械工业出版社,2004,2.
[40]张兴,张崇巍,曹仁贤.光伏并网逆变器非线性控制策略的研究[J].太阳能学报,2002(23):770-773.
[41]林磊.三电平逆变器控制系统研究.华中科技大学硕士学位论文.武汉,华中科技大学图书馆,2004.
[42]吴浩伟,段善旭.基于重复和PI控制的中频逆变器符合控制方案[J].电力电子技术,2006,40(4):38-40.
[43]H J Jiang.DSP based implementation of a digitally controlled single phase PWM inverter for UPS,IEEE-INTELEC99,1999:221-224.
[44]吴杰,茆美琴.基于重复控制算法的光伏并网逆变的研究[J].电源技术,2005.
[45]韩郁,詹长江,赵良炳,等.三电平并联型电能质量调节器的控制技术研究[J].清华大学学报,2000,40(3):40-43.
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