直驱型风力发电机组网侧变流器低电压穿越及电压不平衡运行仿真研究
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摘要
随着风力发电产业的飞速发展,风电机组大规模并网运行,其稳定性对电网安全极为重要。直驱型永磁同步风力发电机组因其具有能量转换效率高、可靠性高、并网功率控制灵活等优点成为当前的主流机型之一。本文以直驱型风力发电机组网侧变流器为研究对象,分别针对系统发生电压跌落故障和电压不平衡时的运行控制技术进行了研究,并通过仿真验证了控制策略的正确性。
首先对风电产业和风力发电技术的发展现状进行了调查研究,分析研究了目前风力发电机组技术中的低电压穿越问题和不平衡运行问题及其研究现状,确定了本文的研究对象和主要内容。
其次研究了机侧、网侧变流器的数学模型和稳态控制策略。分析了直驱型永磁同步风力发电机组的结构和原理,建立了永磁同步发电机和网侧变流器的稳态数学模型,对机侧变流器基于转子磁链定向的定子零d轴电流转速控制,网侧变流器基于电网电压定向的直流电压及有功无功解耦控制策略进行了研究；根据数学模型和控制策略,在PSCAD/EMTDC仿真环境中建立了机组仿真模型,并对机侧变流器的最大功率跟踪、网侧变流器的直流侧电压控制和有功、无功解耦控制进行了仿真研究。仿真结果验证了上述控制策略的有效性。
然后研究了电网发生电压跌落时网侧变流器的低电压穿越问题。简要分析了国内外典型的风电并网低电压穿越标准；研究了电压跌落的原因、分类和检测方法；分析研究了直驱风电机组的低电压运行特性。为实现直驱风力发电机组系统的低电压穿越,分别研究了直流侧Crowbar保护电路控制策略和网侧变流器运行在无功补偿模式两种控制策略,并进行了仿真研究。
最后研究了网侧电压不平衡时网侧变流器的运行控制技术。基于向量对称分解法分析了网侧电压不平衡情况下网侧变流器的瞬时功率传输特性,对负序电压引起直流电压脉动的原因进行了分析；在此基础上,提出了抑制直流侧电压二倍频波动的网侧参考电流算法,采用正负序电流分别控制的策略,对采用上述电流算法和控制策略实现网侧变流器电压不平衡运行的控制效果进行了仿真分析。仿真结果表明了所提算法和控制策略的有效性。
With the rapid development of wind power industry, large-scale wind power turbines connect to the grid, their stable operation is very important to the security of grid. Direct-drive wind power system because of its advanced performance of high energy conversion efficiency, high reliability and flexibility of power control becomes one of the mainstream models. In this paper, the grid-side converter of grid-connected direct-drive wind generator is studied. Its control strategies of low voltage fault ride through when system voltage balanced drops and unbalanced voltage occurs are researched. The simulation results show the correctness and effectiveness of the control strategies.
First, the development and research status of the wind power industry and wind power generation technology is investigated. A brief analysis of the issues of the low voltage and grid voltage unbalanced fault existing in wind power generation system technology, which identified the study object and the main content of this paper.
Second, the structure and principle of direct-drive permanent magnet synchronous wind power system is introduced. The steady-state mathematical models of permanent magnet synchronous generator (PMSG) and grid-side converter are established. Generator-side converter control based on rotor flux orientation of stator zero d-axis current control, grid-side converter based on system voltage oriented, DC voltage control strategy and active and reactive decoupling control strategies have been discussed.; According the mathematical models and control strategies, a simulation model is built based on the PSCAD/EMTDC simulation software, and the maximum power point tracking, DC side voltage control of the grid-side converter, decoupling control of active and reactive power were simulated and analyzed.
Then, briefly introduced the domestic and international typical standards of wind power connection to the grid on low voltage fault ride through (LVRT); analyzed the causes and classifications of the voltage drop and its testing methods; analyzed low voltage operation characteristics of direct-drive wind turbines. For the realization of direct-drive wind turbine system through the low voltage fault, respectively studied the control strategies of DC side Crowbar protection circuit and control strategy of grid-side converter operating on the STATCOM model.
Finally, The stable operation of the grid-side converter under abnormal condition of unbalanced grid voltage drop is studied. Using the method of symmetrical component, a grid-side converter instantaneous power mathematical model under system unbalanced voltage has been established. DC voltage fluctuation caused by negative sequence voltage is analyzed. On this basis, in order to suppress doubler fluctuations in DC voltage, calculated the reference current according to a given power. With the independent control of the positive and negative sequence current control strategies, grid-side unbalanced voltage control effect of control strategies proposed were simulated. Simulation results show the effectiveness of the proposed control strategy.
首先对风电产业和风力发电技术的发展现状进行了调查研究,分析研究了目前风力发电机组技术中的低电压穿越问题和不平衡运行问题及其研究现状,确定了本文的研究对象和主要内容。
其次研究了机侧、网侧变流器的数学模型和稳态控制策略。分析了直驱型永磁同步风力发电机组的结构和原理,建立了永磁同步发电机和网侧变流器的稳态数学模型,对机侧变流器基于转子磁链定向的定子零d轴电流转速控制,网侧变流器基于电网电压定向的直流电压及有功无功解耦控制策略进行了研究；根据数学模型和控制策略,在PSCAD/EMTDC仿真环境中建立了机组仿真模型,并对机侧变流器的最大功率跟踪、网侧变流器的直流侧电压控制和有功、无功解耦控制进行了仿真研究。仿真结果验证了上述控制策略的有效性。
然后研究了电网发生电压跌落时网侧变流器的低电压穿越问题。简要分析了国内外典型的风电并网低电压穿越标准；研究了电压跌落的原因、分类和检测方法；分析研究了直驱风电机组的低电压运行特性。为实现直驱风力发电机组系统的低电压穿越,分别研究了直流侧Crowbar保护电路控制策略和网侧变流器运行在无功补偿模式两种控制策略,并进行了仿真研究。
最后研究了网侧电压不平衡时网侧变流器的运行控制技术。基于向量对称分解法分析了网侧电压不平衡情况下网侧变流器的瞬时功率传输特性,对负序电压引起直流电压脉动的原因进行了分析；在此基础上,提出了抑制直流侧电压二倍频波动的网侧参考电流算法,采用正负序电流分别控制的策略,对采用上述电流算法和控制策略实现网侧变流器电压不平衡运行的控制效果进行了仿真分析。仿真结果表明了所提算法和控制策略的有效性。
With the rapid development of wind power industry, large-scale wind power turbines connect to the grid, their stable operation is very important to the security of grid. Direct-drive wind power system because of its advanced performance of high energy conversion efficiency, high reliability and flexibility of power control becomes one of the mainstream models. In this paper, the grid-side converter of grid-connected direct-drive wind generator is studied. Its control strategies of low voltage fault ride through when system voltage balanced drops and unbalanced voltage occurs are researched. The simulation results show the correctness and effectiveness of the control strategies.
First, the development and research status of the wind power industry and wind power generation technology is investigated. A brief analysis of the issues of the low voltage and grid voltage unbalanced fault existing in wind power generation system technology, which identified the study object and the main content of this paper.
Second, the structure and principle of direct-drive permanent magnet synchronous wind power system is introduced. The steady-state mathematical models of permanent magnet synchronous generator (PMSG) and grid-side converter are established. Generator-side converter control based on rotor flux orientation of stator zero d-axis current control, grid-side converter based on system voltage oriented, DC voltage control strategy and active and reactive decoupling control strategies have been discussed.; According the mathematical models and control strategies, a simulation model is built based on the PSCAD/EMTDC simulation software, and the maximum power point tracking, DC side voltage control of the grid-side converter, decoupling control of active and reactive power were simulated and analyzed.
Then, briefly introduced the domestic and international typical standards of wind power connection to the grid on low voltage fault ride through (LVRT); analyzed the causes and classifications of the voltage drop and its testing methods; analyzed low voltage operation characteristics of direct-drive wind turbines. For the realization of direct-drive wind turbine system through the low voltage fault, respectively studied the control strategies of DC side Crowbar protection circuit and control strategy of grid-side converter operating on the STATCOM model.
Finally, The stable operation of the grid-side converter under abnormal condition of unbalanced grid voltage drop is studied. Using the method of symmetrical component, a grid-side converter instantaneous power mathematical model under system unbalanced voltage has been established. DC voltage fluctuation caused by negative sequence voltage is analyzed. On this basis, in order to suppress doubler fluctuations in DC voltage, calculated the reference current according to a given power. With the independent control of the positive and negative sequence current control strategies, grid-side unbalanced voltage control effect of control strategies proposed were simulated. Simulation results show the effectiveness of the proposed control strategy.
引文
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[7]陈雷,邢作霞,等.大型风力发电机组技术发展趋势[J].可再生能源.2003(1)：27-30.
[8]陈涛,郑同伟.恒速恒频风力发电系统的建模与仿真[J].农村电气化.2010(1)：34-35.
[9]胡申华,王维庆,于书芳.定速风力发电机模型参考自适应控制[J].新疆大学学报：自然科学版.2006,23(4)：482-485.
[10]吴国祥,黄建明,陈国呈等.变速恒频双馈风力发电运行综合控制策略[J].电机与控制学报.2008,12(4)：435-441.
[11]杨之俊,吴红斌,丁明等.故障时双馈风力发电系统的控制策略研究[J].电力系统保护与控制.2010(1)：14-18,36.
[12]谢桦,张德宏,姜久春.双馈风力发电机最大风能追踪策略的研究[J].电气传动.2008,38(12)：19-22.
[13]何玲,李毅梅,张志刚.双馈风力发电机有功、无功的解耦控制研究[J].电气自动化.2008,30(3)：9-11.
[14]Lie Xu(英).基于双馈感应发电机的风电系统在电网不平衡条件下运行性能的改进[J].国外大电机.2009(4)：14-18,22.
[15]肖运启,徐大平,吕跃刚.双馈风电机组一种新型模糊最大风能追踪控制[J].华北电力大学学报.2009,36(6)：1-7.
[16]王琦,陈小虎,纪延超等.变速恒频无刷双馈风电机组的并网研究[J].南京理工大学学报：自然科学版.2008,32(5)：575-580.
[17]姚兴佳,刘君,邢作霞等.双馈变速恒频风电机组的功率特性[J].沈阳工业大学学报.2008,30(3)：270-275.
[18]姚兴佳,鲍洁秋,厉伟等.直驱风电机组变速恒频的控制策略[J].沈阳工业大学学报. 2008,30(4)：399-403,408.
[19]包广清,施进浩,江建中.大功率直驱式变速恒频风力发电技术综述[J].微特电机.2008,36(9)：52-55.
[20]樊俊杰.直驱型风力发电机组发展现状[J].电气牵引.2008(1)：9-11,17.
[21]鲁闯,朱东柏.直驱风力发电控制系统的研究[J].哈尔滨理工大学学报.2009,14(A01)：169-172.
[22]鲁闯,朱东柏.直驱风力发电系统控制方法的研究[J].黑龙江电力.2009,31(1)：7-9,12.
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