基于零序分量的风电场集电线不对称接地故障定位

风电场集电线上并接电源多、电源故障特性复杂，其故障定位问题持续困扰风电运营商。为此提出一种基于零序分量的集电线不对称接地故障新型定位方案。在定义无分支区域的基础上，充分考虑风机与风电场零序分量之间的特殊关系，分层实现风机无关的故障无分支区域识别与故障测距。首先，引入无分支区域状态信息的概念以反映零序电流主流通路径，通过状态信息的优化匹配识别故障无分支区域。然后，从零序阻抗出发推导故障无分支区域测距模型，并将其转化为优化问题实现故障距离求解。所提方案在较少测点下即可完全消除风机影响，并能有效适用于含分支集电线，同时无需数据严格同步，测距不会出现多解。最后，还设计了线路参数在线计算方案应对线路参数变化问题。仿真结果表明，所提方案较为准确，性能不受风机、故障位置、故障类型、过渡电阻以及数据不同步影响，整体性能优于现有方案。同时也验证了线路参数在线计算的有效性。

Zero-sequence component-based fault localization for asymmetric phase-to-ground faults of collecting lines in wind farms

A large number of power sources with complex fault characteristics are connected to the collecting line of wind farms so that fault localization for the line is difficult. This problem has been plaguing wind power operators. Therefore, this paper presents a zero-sequence component-based fault localization scheme for asymmetric phase-to-ground faults of collecting lines. Starting by defining the branch-free area and fully considering the special relationship between wind turbines (WTs) and zero-sequence components of wind farms, the WT-independent identification and fault distance calculation for the faulty branch-free area can be realized hierarchically. First, the concept of status information of branch-free areas is introduced to reflect the main flow path of zero-sequence current. Then the faulty branch-free area can be identified by using optimization to match the status information. Second, a fault distance calculation model of the faulty branch-free area is derived from zero-sequence impedance, and the solution problem of this model is transformed into an optimization problem to obtain the fault distance. The proposed localization scheme can completely eliminate the effect of WTs with only a few measuring points and effectively adapt to the collecting line with branches. In addition, strictly synchronous data is not necessary for this scheme and multiple solutions are avoided. Finally, in order to deal with line parameter variation, online calculation of line parameters is also designed. Simulation results verify that this localization scheme is accurate and not affected by WTs, fault locations, fault types, fault resistance and asynchronous data, and the overall performance is better than that of existing schemes. The effectiveness of online calculation of line parameters is also proved. This work is supported by the National Natural Science Foundation of China (No. 51677072).