双馈型风电场并网线路单端故障测距性能分析及改进

Performance analysis and improvement of single-terminal fault location in transmission lines with DFIG wind farm connecting

兆瓦级双馈风电场受机组类型、装机容量、低电压穿越控制策略等综合因素影响,风电场故障后不同序分量的等值阻抗变化特性不同,且通过对故障支路的影响作用于系统侧,使得无论是依托于主后备距离保护的单端阻抗法测距,还是依托于主保护差动保护的双端阻抗法故障测距均存在较大的测距误差。针对以上问题,建模分析兆瓦级双馈风电场并网故障出力特性;基于分布参数模型,针对利用故障点电流相位拟合的单端阻抗测距算法,量化分析影响故障测距精度的关键因素,分别从系统侧和风电场侧提出基于相位误差补偿的改进单端故障测距算法,显著提高了测距精度。该文成果同时也可应用于风电场并网线路距离保护的设计和整定应用。

The variation characteristics of sequence equivalent impedance of MW DFIG wind farms are absolutely different due to the complicate impacts of wind generator unit type,capacity,and low voltage ride through control strategy etc.The dynamic changing of the sequence equivalent impedance of wind farm will also indirectly influence the measurement at the power system side by the effects of fault branches,hence there are big fault location errors for single terminal impedance fault location at power system side,and for two terminal impedance fault location.According to the problem,this paper built a MW DFIG wind farm model and analyzed its transientoutput characteristics,quantified the key factors producing the fault location errors,and then proposed an improved algorithm based on phase error compensation.The simulations proved good performance of the novel algorithm.The achievement in this paper also can apply into the design and setting of distance protection in transmission lines with wind farms connection.