大型风电场对工频故障分量距离保护影响的研究

摘要

With the maturity of the technology of wind generation, more and more large wind farms have been put into operation. The variation of operational mode for wind farms and its weak-source feature will exert some impacts on transmission line relays. The paper studies the basic principle of distance protection using power fault component, and further researches the impact of the change of operational mode and weak-source feature of wind farms on protection. An improvement of traditional distance protection is put forward by analyzing the equation of phase comparison under voltage phase graph. The analysis shows that the operational mode of wind farm can rarely impose impact on distance relay using power fault component when there is occurring metallic faubecause the equivalent impedance of positive and negative sequence of wind farms is bigger than system impedance, it makes phase-to-phase relays can resist little transition resistance, while because the zero sequence impedance of wind farms is smaller than that of the system, ground protection can resist transition resistance to some degree. Under the platform MATLAB/Simulink, a wind farm connecting grid simulation model is given, and the paper studies the impact of wind farms on relays and conducts the operational behavior comparison between improved and unimproved relays when faults occur. The result from simulation is in line with the theoretical analysis.%　　随着风力发电技术日趋成熟，越来越多的大型风电场开始投入运行。由于风电场运行方式的变化及其弱电源特性，会对输电线路的保护造成一定的影响。研究了工频故障量距离保护的基本原理及风电场运行方式的多变性，并在此基础上进一步分析了风电场的运行方式的变化和弱电源特性对保护的影响，通过利用电压相量图分析保护判据的比相表达式提出了对传统距离保护的改进。通过分析可知，在发生金属性故障时，工频变化量距离继电器几乎不受风电场运行方式的影响，但由于风电场正、负序等值阻抗较系统阻抗大，使得相间保护耐受过渡电阻的能力很小，而受风电场零序阻抗较大的影响，接地保护耐受过渡电阻的能力较强。以Matlab/Simulink为平台建立了风电场并网的仿真模型，研究了风电场对保护的影响及对比保护改进前后在故障时的动作行为，仿真结果与理论分析相吻合。