核电厂辅变空载运行期间辅助电源单相断相故障特征分析及应对措施

Characteristic Analysis and Countermeasures of Single-phase Open Phase Fault of Auxiliary Power Supply during No-load Operation of Auxiliary Transformer in Nuclear Power Plant

目前,国内和国外的核电厂设计基准只考虑了电压完全丧失对于核电厂运行的影响,而忽略了断相故障对于核安全的挑战。辅助变压器在空载运行状态下发生断相故障时电气量十分微弱,因此如何检测并判别断相是核电厂中最为关心的问题。本文重点研究辅助变压器空载时的断相故障,结合对称分量法和变压器原理分析了辅助变压器空载运行状态下高压侧发生单相断相时的电气参数特征,运用ETAP软件建立了“华龙一号”核电厂厂用电系统仿真模型并进行了仿真分析。基于理论分析和仿真分析的结果,提出了辅助变压器空载时高压侧发生单相断相故障的应对措施,提高了厂外辅助电源的供电可靠性,有利于核电厂安全有序的运行。本文中辅助变压器空载状态下高压侧发生断相故障的电气参数特征研究分析结果对于辅助变压器断相保护方案的配置和断相保护设备的研发都具有指导意义。

At present,the design basis of nuclear power plants at home and abroad only considers the impact of the complete voltage loss during the operation of the nuclear power plant,while ignoring the challenge of open phase failure to nuclear safety.When the auxiliary transformer has a phase failure under no-load state,the electrical quantity is very weak,so it is the most concerned open phase problem in nuclear power plant.This paper focuses on the open phase fault of the auxiliary transformer under no-load condition.Combined with the symmetrical component method and transformer principle,the electrical parameter characteristics of single-phase open phase on the high-voltage side of the auxiliary transformer under no-load condition are analyzed.Using the ETAP software,the simulation model of the power system of HPR1000 nuclear power plant was established and the simulation analysis was carried out.Based on the results of theoretical analysis and simulation analysis,the countermeasures of single-phase open phase fault on the high-voltage side of the auxiliary transformer are put forward,which improves the power supply reliability of the auxiliary power supply outside the plant and is conducive to the safe and orderly operation of nuclear power plant.The study and analysis results of the electrical parameter characteristics of the open phase fault on the high voltage side of the auxiliary transformer under the no-load state have guiding significance for the configuration of the open phase protection scheme of the auxiliary transformer,and the R&D of the open phase protection equipment.