基于序分量综合阻抗的母线保护原理

A Novel Busbar Protection Based on Sequence Component Integrated Impedance

提出了母线正序故障分量综合阻抗、负序综合阻抗和零序综合阻抗的概念,通过分析母线区内、外故障时3种综合阻抗的特征,分别利用阻抗幅值和相角构成了基于正序故障分量综合阻抗、负序综合阻抗以及零序综合阻抗的母线保护原理。3种保护原理在母线区内、外故障时特征明显,判据简单、易整定,而且原理本身不受3/2断路器接线的母线区内故障汲出电流以及过渡电阻的影响。当母线区外故障电流互感器(TA)饱和时,利用各个序分量综合阻抗相角所构成的TA饱和识别判据能够可靠地将母线保护闭锁,从而避免保护误动;当母线区内发生故障有TA饱和时,保护性能不受影响,能够可靠地快速动作。基于正序故障分量综合阻抗的母线保护原理可以反映各种类型的母线故障,对于最严重的三相短路故障可以快速切除;基于负序、零序综合阻抗的母线保护原理则可以在故障后长期应用,不受系统振荡的影响,而且对于高阻接地故障依然能灵敏动作。3种保护原理可构成完整的母线保护方案。EMTP仿真结果验证了新原理的有效性和可行性。

The concepts of integrated impedance of positive-sequence bus-bar fault component and those of negative-sequence integrated impedance and zero-sequence integrated impedance are proposed. By means of analyzing the characteristics of above-mentioned integrated impedances under the faults inside and outside the bus-bar protection zone, three bus-bar protection principles based on integrated impedance of positive-sequence bus-bar fault component and those of negative-sequence integrated impedance and zero-sequence integrated impedance are established by amplitudes and arguments of the sequence component integrated impedances respectively. For the three protection principles the bus-bar faults inside and outside the potection zone show features with obvious differences, so the criteria are simple and easy to set, besides the proposed protection principles themselves immune to the transition resistance and the out-flowing current of bus-bar fault inside the protection zone under the one and a-half circuit breaker layout. Under the CT saturation caused by fault outside bus-bar protection zone the bus-bar protection can be blocked to prevent protection misoperation by the discriminating criterion of CT saturation that is constituted by phase angles of sequence component integrated impedances; under the CT saturation during the fault inside bus-bar protection zone, the performance of the protection is not affected and the protection can operate fast and reliably. The bus-bar protection principle based on integrated impedance of positive-sequence fault component can reflect various types of bus-bar faults and it makes the possibility of rapidly switching off the most severe three-phase short-circuit fault; the bus-bar protection principles based on negative-sequence and zero-sequence integrated impedances, which is not affected by system oscillation, can be applied in a long-term after the fault, and the protection can still be sensitively operate under high-resistance earth-fault. The proposed three protection principles can constitute an integrated protection scheme. The effectiveness and feasibility of the proposed protection principles are verified by results of EMTP simulation.