Distance Protection of Lines Connected to Induction Generator-Based Wind Farms During Balanced Faults
Distance Protection of Lines Connected to Induction Generator-Based Wind Farms During Balanced Faults
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DOI：
10.1109/tste.2014.2336773
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发表时间：
2014-08
影响因子：
8.8
通讯作者：
A. Hooshyar;M. Azzouz;E. El-Saadany
中科院分区：
文献类型：
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作者：
A. Hooshyar;M. Azzouz;E. El-Saadany
风电场(WF)越来越多地与高压(HV)电网集成，距离继电保护通常是高压电网的保护选择。本文揭示了基于感应发电机(IG)的无功补偿系统在平衡故障时距离保护存在的一些严重缺陷。结果表明，对于鼠笼式IG(SCIG)WFS，距离保护变得不安全，而对于双馈IG(DFIG)WFS，由于这种WFS特有的操作场景，以及对现有继电保护实践的不熟悉，继电保护性能完全不可靠。检测到的故障很容易导致不必要的WF跳闸，从而危及新的电网规范所追求的目标，这些目标迫使WFS在扰动期间保持与电网的连接。此外，还提出了一种改进的允许越界转移跳闸(POTT)方案和故障电流分类技术来解决这两种基于IG的WF的问题，恢复了距离保护在整个线路长度上的准确无延迟保护。全面的性能评估证实了本文的结论，并验证了所提出的解决方案在所有运行条件下的有效性。对于基于DFIG的具有非零撬棒电阻的WFS来说，结果尤其有希望，这是距离继电器最有可能遇到的情况。
Wind farms (WFs) are increasingly integrated with high-voltage (HV) grids, for which distance relaying is normally the protection of choice. This paper reveals some serious defects of distance protection for the lines connected to induction generator (IG)-based WFs during balanced faults. It is shown that for the squirrel cage IG (SCIG) WFs, distance protection becomes insecure, while for the doubly fed IG (DFIG) WFs, the relay performance is utterly unreliable, due to operating scenarios that are unique to such WFs, and are unfamiliar to the existing relaying practices. The detected failures can easily result in unnecessary WF tripping, thus jeopardizing the objectives pursued by the new grid codes that oblige WFs to remain connected to the grid during disturbances. Moreover, a novel modified permissive overreach transfer trip (POTT) scheme along with a fault current classification technique is proposed to address these problems for both types of IG-based WFs, and the accurate nondelayed protection of a distance relay over the entire line length is restored. A comprehensive performance evaluation confirms the findings of this paper and validates the efficacy of the proposed solution for all operating conditions. Results are particularly promising for the DFIG-based WFs with nonzero crowbar resistance, which is the most likely situation confronted by distance relays.