500kV变电站主变压器中压侧失灵判据缺陷分析及应对策略

Analysis on Failure Criterion Defects in Medium-voltage Side of Main Transformer in 500 kV Substation and Its Countermeasures

500 kV变电站主变压器中压侧失灵判据的目的是为了中压侧开关失灵之后通过主变压器后备保护来跳三侧开关,隔离中压侧故障点,避免电网事故的扩大。失灵启动必须满足两条件:一是保护动作不返回;二是存在失灵电流。当在特殊区域发生故障时,若两者配合不好将引起保护的拒动,故障不能及时切除,将会影响主变压器设备的安全及电网的稳定。基于此,以某500 kV变电站主变压器保护配置为例来分析其隐患,并提出相应的对策,希望对此类工程设计和二次验收提供一定的实用参考价值。

The failure criterion in medium - voltage side of main transformer in 500 kV substation are designed to trip three sides through the backup protection of main transformer when the medium - voltage side breaker failed to jump, so as to isolate the fault point in medium - voltage side and avoid the expansion of the accident in power grid. The malfunction start - up must meet the following two conditions： the protection lasting action and failure current. When the failure occurs in a special area, a bad combination of the two factors will cause the protection to refuse to trip, and the fault cannot be removed, which will in- fluence the security of main transformer equipment and the stability of the grid. On this basis, taking the protection configura- tions of main transformer in a 500 kV substation for example, the hidden dangers are analyzed and the appropriate counter- measures are proposed, which provides some practical references for such engineering design and secondary acceptance.