Analysis and Solutions of Existing Acceleration Protection Problems in 900 MW Unit of Daya Bay Nuclear Power Station

In this paper, an incident in Daya Bay 900 MW nuclear unit, in which the turbine-generator acceleration protection action was initiated by three-phase short circuit fault of power grid and then manually tripped by the operator, was introduced, and the related issues were analyzed.An improvement measure to cancel the response of the high pressure steam valve to the acceleration protection have been put forward. The safety stability of the grid and nuclear generator unit has been improved by improving the related automatism and protection and their control strategy.