摘要
由于光伏发电系统的结构及其所处环境十分复杂,局部阴影或光照不均造成的阵列失配现象,使P-U特性由单峰值曲线变为多峰值曲线,不仅使光伏阵列的输出功率降低,其热斑效应还会造成安全和可靠性问题。目前,解决局部阴影影响的方法有两种:一是改变光伏阵列发电系统的结构,把集中式系统转变为多串式系统,但是这种办法会造成系统中变换器、控制器的数量大大增加,使整个系统的结构变复杂、提高成本、降低了可靠性。其二是在集中式光伏阵列发电系统中,应用全局峰值判定的最大功率点跟踪算法,但这种算法复杂,对控制器计算速度和精度要求较高,不易在硬件中实现。
为解决输出功率受局部遮荫影响的问题,本文提出了一种光伏阵列的局部重构方法,通过改变光伏阵列的连接方式,用没被遮荫的光伏组件去补偿被遮荫的组件,改善了局部阴影下光伏阵列的输出特性,同时也避免了复杂的优化算法。
为提高补偿的效率,本文首次将遮荫度模型的概念运用到光伏阵列模糊控制重构算法中。根据电池组各子模块遮荫度的不同,用专家系统的经验知识归纳总结模糊规则,经过模糊推理得出所需补偿电池组件的数目,用开关矩阵进行算法的实现,达到了降低光伏阵列的输出功率损耗的目的。
搭建了光伏电池重构系统的硬件电路,在室外不同局部阴影条件下进行了实验。实验结果表明,光伏阵列经过重构后,被遮荫子模块的电压和输出电流值基本恢复到被遮荫前的水平。当阴影条件发生改变时,光伏阵列会再次重构,说明其对于环境的变化有着较好的响应能力。
As the complicated structure of the PV generation systems and variety of application environments, the mismatch and hot spot phenomena caused by partial shading or non-uniform illumination not only heavily affect the output characteristics of photovoltaic arrays, but also create safety and reliability problems. The P-U curve of PV arrays will have the characteristics of multi-summit under partial shading, not only a serious decline in global peak power, and the local peak power also caused a great disturbance. At present, change the structure of PV generation systems into multi-string systems, but this approach cause lower reliability, the structure of the whole system change complex, increases the cost. Second, the application of global peaks for MPPT algorithm in the centralized PV generation systems, but it is complex to implement in hardware and the controller needs high speed and high precision.
The output power of PV arrays is mainly affected by the irradiance. This paper proposes a reconfiguration method. PV arrays change the interconnection in order to change the distribution of the shadow, thus improving the output characteristics of PV arrays, to reduce the impact on the irradiance under partial shading, to reduce the decline in global peak power.
For local reconfiguration method in PV arrays, this paper uses shading degree model to represent the size of decline in the irradiance of each submodule. TCT PV array is divided into a fixed solar array and an adaptive bank, and proposes the shading degree model-based fuzzy control reconfiguration algorithm. According to the shading degree of the submodules, the expert system summarizes the fuzzy rules. The number of modules to compensate is determined by the fuzzy inference. Using a switching matrix to change the connection of the adaptive bank and the fixed part of a PV array, the loss of the output power is reduced.
In order to verify the validity of algorithm, the hardware circuit of the control system with partial shading condition is constructed. The experimental results show when the partial shade phenomenon occurs, the system can quickly respond to the changes of external environments.
引文
[1]常边疆,世界各国重视推广太阳能利用技术,广西节能,2006,34(2):17~18
[2]冯垛生,宋金莲,赵慧等,太阳能发电原理与应用,北京:人民邮电出版社,2007.20~36
[3]李申生,世界范围的常规能源危机,太阳能学报,2003,53(2):15~19
[4]王长贵,王斯成,太阳能光伏发电实用技术,北京:化学工业出版社,2005.1~17
[5]黄亚平,太阳能光伏发电研究现状与发展前景探讨,广东白云学院学报,2007,14(2):113~118
[6]钱伯章,国际可再生能源最新动态,中国建设动态,2007,67(4):59~66
[7]赵春江,杨金焕,太阳能光伏发电应用的现状与发展,节能技术,2007,25(5):461~462
[8]陆维德,太阳能利用技术发展趋势评述,世界科技研究与发展,2007,1(29):95~99
[9]郭廷杰,吕应运,依法促进可再生能源加速发展的探讨,能源政策研究,2006,23(5):44~48
[10]梁宗存,沈辉,李戬洪,太阳能电池研究进展,能源工程,2000,4:8~11
[11]汪建军,刘金霞,太阳能电池及材料研究和发展现状,浙江万里学院学报,2006,5:73~74
[12]苏建徽,余世杰,赵为等,硅太阳电池工程用数学模型,太阳能学报,2001,22(4):409~412
[13]孙园园,肖华锋,谢少军,太阳能电池工程简化模型的参数求取和验证,电力电子技术,2009,43(6):44~46
[14]翟载腾,程晓舫,杨臧健等,太阳电池一般电流模型参数的解析解,太阳能学报,2009,30(8):1078~1082
[15]Walker,G.,Evaluating MPPT Converter Topologies Using a MATLAB PV Model,Journal of Electrical & Electronics Engineering,2001,21(1):49~56
[16]李金刚,智能光伏组件的研究与应用:[硕士学位论文],江南大学,2007
[17]周小义,基于独立光伏组件并网逆变器的研究:[硕士学位论文],合肥工业大学,2007
[18]张凌,单相光伏并网逆变器的研制:[硕士学位论文],北京交通大学,2007
[19]焦在强,单级式并网型光伏发电系统用逆变器的研究:[博士学位论文],合肥工业大学,2004
[20]刘邦银,段善旭,康勇,局部阴影条件下光伏模组特性的建模与分析,太阳能学报,2008,29(2):188~192
[21]张利,光伏电池特性研究:[硕士学位论文],华北电力大学,2008
[22]刘素梅,光伏方阵失配现象研究:[硕士学位论文],汕头大学,2008
[23]王培珍,光伏阵列故障状态的识别研究:[博士学位论文],合肥工业大学,2005
[24]陈如亮,光伏热斑现象及多峰最大功率跟踪的研究:[硕士学位论文],汕头大学,2007
[25]徐鹏威,刘飞,刘邦银等,几种光伏系统MPPT算法的分析比较及改进,电力电子技术,2007,41(5):3~5
[26]崔岩,太阳能光伏系统MPPT控制算法的对比研究,太阳能学报,2006:535~539
[27]杨海柱,金新民,最大功率跟踪的光伏井网逆变器研究,北京交通大学学报,2004:65~68
[28]杨海柱,金新民,并网光伏系统最大功率点跟踪控制的一种改进措施及其仿真和实验研究,电工电能新技术,2006,25(1):63~68
[29]陈桂兰,孙晓,李然,光伏发电系统最大功率点跟踪控制,电子技术应用,2001,27(8):33~35
[30]雷元超,陈春根,沈骏,光伏电源最大功率点跟踪控制方法研究,电工电能新技术,2004,2(3):76~80
[31]王庆章,赵庚申,许盛之等,光伏发电系统最大功率点跟踪控制方法研究,南开大学学报(自然科学版),2005,38(6):74~79
[32]江小涛,吴麟章,周明杰,太阳电池最大功率点跟踪研究,通信电源技术,2005,22(4):33~36
[33]肖景良,徐政,林崇等,局部阴影条件下光伏阵列的优化设计,中国电机工程学报,2009,29(11):119~124
[34]陈昌松,段善旭,殷进军,基于神经网络的光伏阵列发电预测模型的设计,电工技术学报,2009,24(9):153~158
[35]Miyatake,Toriumi,Endo,Fujii,A Novel maximum power point tracker controlling several converters connected to photovoltaic arrays with particle swarm optimization technique,2007 European Conference on Power Electronics and Applications,2007.1~10
[36]Sera,Teodorescu,Hantschel,Knoll,Optimized Maximum Power Point Tracker for Fast-Changing Environmental Conditions,IEEE Transactions on Industrial Electronics,2008,55(7):2629~2637
[37]K.Kobayashi,I.Takano and Y.Sawada,A study on a two stage maximum power point tracking control of a photovoltaic system under partially shaded insolation conditions,Power Engineering Society General Meeting,2003.2612~2617
[38]Patel,Agarwal,Maximum Power Point Tracking Scheme for PV Systems Operating Under Partially Shaded Conditions,IEEE Transactions on Industrial Electronics,2008,55(4):1689~1698
[39]Nguyen,Lehman and Kamarthi,Solar Photovoltaic Array's Shadow Evaluation Using Neural Network with On-Site Measurement,Electrical Power Conference, 2007. EPC 2007. IEEE Canada,2007.44~49
[40]Toshihiko Noguch,Shigenori Togashi,Ryo Nakamoto,Short-current pulse-based maximum power point tracking method for multiple photovoltaic and converter module system,IEEE Transactions on Industrial Electronics,2002,49(1):217~222
[41]Dzung Nguyen,Lehman,A reconfigurable solar photovoltaic array under shadow conditions,Applied Power Electronics Conference and Exposition,2008. APEC 2008. Twenty-Third Annual IEEE,2008.980~986
[42]Syafaruddin,Karatepe,Hiyama,Artificial neural network-polar coordinated fuzzy controller based maximum power point tracking control under partially shaded conditions,IET Renewable Power Generation,2009,3(2):239~253
[43]云志刚,杨宏,李文滋,光伏组件中电池遮挡与I-V曲线特性变化关系,第八届全国光伏会议暨中日光伏论坛论文集,深圳,2004.670~673
[44]Yona A,Senjyu T,Funabashi T,Application of recurrent neural network to short-term-ahead generating power forecasting for photovoltaic system,IEEE Power Engineering Society General Meeting,2007.
[45]Dzung Nguyen,Brad Lehman,An Adaptive Solar Photovoltaic Array Using Model-Based Reconfiguration Algorithm , IEEE Transactions on Industrial Electronics,2008,55(7):2644~2654
[46]G. Velasco,J.J. Negroni,F. Guinjoan,R. Pique,Irradiance equalization method for output power optimization in plant oriented grid-connected PV generators,Power Electronics and Applications European Conference,2005.1~10
[47]R. Candela,V. Di Dio,E. Riva Sanseverino,P. Romano,Reconfiguration Techniques of Partial Shaded PV Systems for the Maximization of Electrical Energy Production,ICCEP '07. International Conference on Clean Electrical Power,2007.716~719
[48]Guillermo Velasco,Francesc Guinjoan,Robert Piqué,Grid-Connected PV Systems Energy Extraction Improvement by means of an Electric Array Reconfiguration (EAR) Strategy:Operating Principle and Experimental Results,Power Electronics Specialists Conference,2008.1983~1988
[49]易继锴,侯媛彬,智能控制技术,北京:北京工业大学出版社,1999.177~214
[50]张超,何湘宁,非对称模糊PID控制在光伏发电MPPT中的应用,电工技术学报,2005,20(10):72~75
[51]刘永军,万频,王东海等,自适应模糊算法在光伏系统MPPT中的应用,太阳能学报,2008,29(6):657~661
[52]LI Wei,ZHU Xin jian,CAO Guang yi,Fuzzy Variable Structure Control of Photovoltaic MPPT System,Journal of Donghua University(Eng. Ed.),2006,23(4):69~75
[53]Qingrong Zeng,Liuchen Chang,Riming Shao,Fuzzy-logic-based maximum power point tracking strategy for Pmsg variable-speed wind turbine generation systems,Canadian Conference on Electrical and Computer Engineering,CCECE 2008.,2008.405~410
[54]沈文,Eagle lee,詹卫前,AVR单片机C语言开发入门指导,北京:清华大学出版社,2003.133~172
[55]陈冬云,杜敬仓,任柯燕等,ATmega128单片机原理与开发指导,北京:机械工业出版社,2006.213~228