文章摘要
张前进,周林,解宝.针对电网阻抗的大型光伏并网系统稳定性分析与提高策略[J].电力系统自动化. DOI: 10.7500/AEPS20170413004.
zhangqianjin,周林,Xie Bao.Analysis and Improvement Strategy for Stability of Large-Scale Grid-Connected Photovoltaic System Considering Grid Impedance[J].Automation of Electric Power Systems. DOI: 10.7500/AEPS20170413004.
针对电网阻抗的大型光伏并网系统稳定性分析与提高策略
Analysis and Improvement Strategy for Stability of Large-Scale Grid-Connected Photovoltaic System Considering Grid Impedance
DOI:10.7500/AEPS20170413004
关键词: 大型光伏并网系统  电网阻抗  稳定性  电能质量;虚拟阻抗
KeyWords: large-scale grid-connected PV system  grid impedance  stability  power quality  virtual impedance
上网日期:2017-09-08
基金项目:国家自然科学基金:大型光伏并网系统谐振机理及抑制策略研究(51477021)
作者单位E-mail
张前进 重庆大学 输配电装备及系统安全与新技术国家重点实验室 973382409@qq.com 
周林 重庆大学 输配电装备及系统安全与新技术国家重点实验室 zhoulin@cqu.edu.cn 
解宝 重庆大学 输配电装备及系统安全与新技术国家重点实验室 1261889141@qq.com 
摘要:
      大型光伏并网系统中,一般采用多逆变器并联结构来提高总的光伏并网系统的容量。当各发电单元采用相同的元件、控制策略及电路结构时,对于多个光伏发电单元相并联的系统,随着并网容量的增加,电网阻抗的值相对于某一个光伏发电单元而言将会被等效放大,光伏并网系统可能出现不稳定现象,特别是在光伏电站不断扩容后,较大的等效电网阻抗会直接导致逆变器控制策略失效,系统出现剧烈震荡现象,从而导致并网失败。本文在光伏并网系统开关平均模型的基础上,详细分析了电网阻抗对于逆变器输出电压和电流的影响,并针对电网阻抗导致的光伏并网系统的不稳定现象,采用虚拟阻抗思想,通过控制手段等效消除电网阻抗对并网电压稳定性和并网电能质量的影响,从而保证系统的稳定运行。最后通过仿真分析和试验验证了理论的正确性。
Abstract:
      In the large-scale grid-connected photovoltaic system, the multi-inverter paralleled structure is used to improve the capacity of the system. When all the power units with the same component, control circuit structure and strategy, the value of grid impedance will be equivalently enlarged with respect to single PV power generation unit, and the PV system may become unstable with the increase of system capacity. If the system capacity keeps increasing, the equivalent impedance of power grid will directly lead to the control failure of inverters, system resonance and failure of connecting with the grid. This paper, based on switch averaged model, analyses the influence of grid impedance on the output current and voltage in detail. And, using a new kind of feed-back control strategy to improve the stability of connecting point voltage and power quality to guarantee the system normal operation. Finally, the correctness of the theory is verified by the simulation analysis and experiment.
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