三峡电站机组单机容量大、装机台数多，由于机组的辅助系统复杂，对厂用电的依赖性强，一旦厂用电中断或发生扰动，都会引起机组辅助系统工作异常，进而影响主机的运行。同时，因三峡工程建设周期长，投产初期未形成完整的厂用电系统，厂用电本身的可靠性较低，发生了多起因厂用电的原因造成机组跳闸、停机的事件。通过改进完善机组辅助设备电源和控制回路、增加机组出口开关以提高机组自供电源的灵活性、增设三峡电站自备保安电源电站、完善厂用电网络等措施，极大地提高了厂用电和机组运行的可靠性。

The Three Gorges power plant is large in both generator capacity and unit numbers. Due to the complex of the unit’s auxiliary system and its strong dependence on the plant auxiliary power, any breakdown or disturbance of the plant auxiliary power will lead to abnormal operation of the unit’s auxiliary system, subsequently affecting the operation of the main generator units. In the meantime, due to the long construction period of the Three Gorges project, the plant auxiliary power system was incomplete at the initial commissioning stage and low in reliability, which led to frequent trips and outage of generator units. Many measures have been taken, such as improving the unit’s auxiliary systems and control circuit, increasing the exit on-offs of generator units for improving the flexibility of generator’s power supply system, building the self-supply power plant for the Three Gorges power plant, and perfecting the plant auxiliary power network, and as a result, the power plant’s reliability has significantly improved in auxiliary power and the generator unit’s operation .