基于频域模型匹配的双馈风电场送出线路纵联保护方案

Longitudinal Protection Scheme of Doubly-fed Wind Farm Transmission Lines Based on Frequency Domain Model Matching

针对风电场多机并网暂态模型难以准确解析导致的风场送出线路保护适应性问题,该文建立双馈风电场多机并网频域等值模型,提出一种基于频域模型匹配值的双馈风电场纵联保护方案。首先,根据双馈风机故障下进入低电压穿越控制模式,推导得到双馈机组电流响应模型。在此基础上,考虑不同馈线阻感之间的耦合关系和锁相环相角偏移影响,建立双馈风电场多机并网频域等值模型。然后,根据送出线路故障网络分析区内外故障模型,定义频域模型匹配值,构造识别送出线路区内外故障的保护判据。最后,在RT-LAB平台搭建仿真模型进行验证,保护方案在送出线路不同位置发生经不同过渡电阻接地故障,均能快速准确切除区内故障。

Aiming at the problem of wind farm transmission line protection adaptability caused by the difficulty of accurate analysis of the multi-machine grid-connected transient model of wind farms,this paper establishes a frequency-domain equivalence model for multi-machine grid-connected doubly-fed wind farms,and proposes a longitudinal protection scheme for doubly-fed wind farms based on the matching values of the frequency domain model.First,according to the low-voltage ride-through control mode under the fault of the doubly-fed fan,the current response model of the doubly-fed unit is derived.On this basis,considering the coupling relationship between different feeder resistance inductances and the influence of phase-locked loop phase angle offset,a multi-machine grid-connected frequency-domain equivalence model of doubly-fed wind farm is established.Then,according to the fault network analysis of the outgoing line fault model,the matching value of the frequency domain model is defined,and the protection criterion for identifying the fault inside and outside the transmission line is constructed.Finally,a simulation model is built on the RT-LAB platform to conduct verification tests,and the protection scheme can quickly and accurately cut off the fault in the area by passing through different transition resistance ground faults at different positions of the transmission line.