风力发电机集团式接入电力系统的故障特征分析  

Analysis on Fault Features of Wind Turbine Generators Concentratedly Connected to Power Grid

作　　者：张保会[1] 王进[1] 李光辉[1] 郝治国[1] 薄志谦 

机构地区：[1]西安交通大学电气工程学院,陕西省西安市710049 [2]阿尔斯通输配电有限公司

出　　处：《电网技术》2012年第7期176-183,共8页Power System Technology

基　　金：国家重点基础研究发展计划项目(973项目)(2009CB219704)~~

摘　　要：我国风电场多为集团式接入电力系统,风电场并网对系统安全运行及继电保护正确动作的影响越来越突出。由于风电场的容量相对较小,而且风机出口电压很低,从高压侧来看,风力发电机、箱式变压器及相应低压电缆相当于一个很大的限流电抗,即风电场侧的正负序等值阻抗远远大于系统侧的等值阻抗;对于零序网络,风电场主变压器的中性点直接接地,故障期间风电场侧的零序等值阻抗仅包括输电线路与主变的零序阻抗。因此风电场侧保护背侧的正负序阻抗远大于零序阻抗,属于典型的弱馈电源系统,风电场侧保护感受到的故障电流几乎全部为零序分量,非故障相电流在幅值与相位上均与故障相电流近乎相同,使保护的正确动作受到很大影响。以某风电场送出线故障为例,对风电场接入后,风电场侧保护感受到几乎全部零序故障电流而不正确动作的现象进行了分析,并在PSCAD/EMTDC下建立了实际风电场模型,对这一现象进行了仿真再现,并对其影响因素进行了分析。Most wind farm in China are connected to power grid in concentratedly way,so the grid-connected wind farms affects both secure operation of power grid and correct action of protective relayings more and more evidently.Due to relatively small capacities of wind farms and low terminal voltage of wind turbine generators,so relative to the high voltage side of power grid,the assembly of wind turbine generators,package transformers and low voltage cables is equivalent to a current-limiting reactor with high impedance,i.e.,the equivalent positive-and negative-sequence impedances are far higher than equivalent impedance at grid side,however,due to direct grounding of main transformer neutrals in wind farm,so the equivalent zero-sequence impedance at wind farm side during faults only includes zero-sequence impedances of transmission lines and main transformers,thus the positive-and negative-sequence impedances at the back side of protections of wind farm is far higher than zero-sequence impedance,and for this reason the wind farm belongs to typical weak power-feed system,and the fault current felt by protections of wind farm is almost the total zero-sequence component of the fault current,meanwhile the currents of non-fault phases are almost the same as the current of fault-phase,so that the correct action of protection of wind farm will be greatly affected.Taking the fault occurred in outgoing line of a certain wind farm as example,the phenomenon that after the connecting the wind farm to power grid the maloperation of protections of wind farm occurred due to the felt current was very near to the total zero-sequence current is analyzed,and a model of the actual wind farm is built by PSCAD/EMTDC for the reappearance of the fault,and by use of the built model the influencing factors of this phenomenon are analyzed.

关 键 词：故障特征 风力发电机 集团式接入 PSCAD/EMTDC 

分 类 号：TM615[电气工程—电力系统及自动化] TM743