事故状态安全停机及备用变压器容量设置

Study on Safe Shutdown under Fault Condition and the Capacity Design of Auxiliary Transformer

分析了1000MW机组典型厂用电接线,计算机组正常运行状态和事故停机状态下厂用电的负荷。根据工艺流程的实际运行情况,探讨出安全停机时高压厂用备用变压器必须带的负荷,从而明确高压厂用备用变压器的容量设置。对《火力发电厂设计技术规程》中的条款"当发电机出口装有断路器或负荷开关时,高压厂用备用变压器的容量可按1台高压厂用工作变压器容量的60%～100%选择"提出修改意见,建议高压厂用备用变压器按1台高压厂用工作变压器容量的100%设置。

It analyzes the wiring of the typical auxiliary system of 1,000 MW units, and it calculates the load of auxiliary system under the normal operation condition and the conditions with station transformer in the state of accident shutdown. According to the actual operation of the process, it calculates the load of auxiliary transformer that is needed when safe shutdown is done, thus deciding the capacity of the auxiliary transformer. It is prescribed in the Technical Code for Designing Fossil Fuel Power Plants that when circuit breaker or load-break switch is installed on the generator outlet, the capacity of the auxiliary transformer should be equipped with 60%N100% capacity of the working transformer. According to the prescription, amendments are proposed in this paper and it is suggested to equip the auxiliary transformer with 100% capacity of that of the working transformer.