Conversion and verification of proportional–integral​ controller parameter in Daya Bay distributed control system modification project

Abstract

The nuclear island analog system in the Daya Bay Nuclear Power Plant is made up of discrete analog boards. Owing to the difficulties in purchasing spare parts and maintaining systems, the overall digital upgrade and modification shall be carried out during the 30-year overhaul period. In view of the difference between analog and digital systems in expressing and processing process signals, this paper proposed the proportional–integral (PI) controller parameter conversion method for digital modification, highlighting the importance of controller input/output range matching in the process of parameter conversion. The Daya Bay process simulation model, minimum digital system, and minimum analog system are built into a system verification platform through a programmable logic controller (PLC). Taking primary single-phase pressure control loop system and downflow pressure control loop system as research objects, the disturbance was introduced through the step of the primary pressure setting value and opening/closing of the second downflow orifice plate respectively, and the adjustment time、 overshoot and other adjustment quality differences in different systems are compared. The correctness of the parameter conversion method is verified through the system verification platform, which not only ensures the correct input of controller parameters of the Daya Bay DCS modification project but also provides invaluable experience for other digital modification projects of analog systems.