牛从直流牛寨站典型故障仿真分析及保护改进建议

Typical Faults Simulation Analysis and Protection Improvement Suggestions of Niu-cong HVDC Niuzhai Station

  • 摘要: 为了研究牛从直流牛寨站发生各典型故障时的故障发展机理以及当前保护系统动作特性,以便为直流控制保护逻辑优化提供理论依据,在牛从直流PSCAD/EMTDC仿真模型中设置牛寨站各典型故障,研究发现牛寨站换流变网侧故障消除后直流系统可快速恢复正常。换流变阀侧及阀区接地故障均导致牛从直流牛寨侧接地极流过强电流,短路故障均导致交流侧发展为三相短路。指出当前牛从直流50 Hz保护存在的弊端,并提出改进措施。根据阀短路特性提出一种新型阀短路保护判据,可与当前保护原理构成双重化保护,为今后直流工程保护系统设计提供理论参考依据。

     

    Abstract: In order to study the development mechanism of faults and the action characteristics of current protection system in Niu-cong HVDC Niuzhai station theoretical basis for HVDC control protection logic optimization is provided. The typical faults of Niuzhai station in the simulation model of Niu-cong HVDC PSCAD/EMTDC is set up. It is found that the HVDC system can return to normal quickly after eliminating the faults on the grid side of converter transformer of Niuzhai station. The grounding fault of valve side of converter transformer and valve area will results in strong current flowing through the grounding electrode of DC Niuzhai side, short circuit faults will leads to the development of three-phase short circuit in AC side. It points out the disadvantage of the current 50 Hz protection and puts forward the improvement measures. According to the characteristics of valve short-circuit, a new criterion of valve short-circuit protection is proposed, which can form dual protection with the current protection principle, and provide theoretical reference for the design of HVDC engineering protection system in the future.

     

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