Development and Application of Full Range Closed-Loop Testing System for DCS Transformation of Daya Bay Nuclear Power Plant

Large-scale transformation projects of distributed control system (DCS) of in-service nuclear power plants are usually characterized by complex compatibility requirements, multiple transformation construction constraints, short construction period, and high quality requirements. Daya Bay Nuclear Power Plant is the first in-service nuclear power plant in China to carry out digital transformation of DCS, and it faces great challenges as there is no precedent in the country to draw reference from. Therefore, a full-range closed-loop testing method of DCS based on hardware-in-the-loop simulation technology is proposed. The simulation model of nuclear power plant process system is introduced into the testing environment of DCS system, and the closed-loop control of DCS on the process system is realized in the testing environment, so that the on-site commissioning, operation and maintenance test of nuclear power plant can be verified in advance in DCS supplier's factory. At present, it has been applied to the 30-year instrument and control system transformation project of Daya Bay Nuclear Power Plant. After full-range closed-loop verification, the DCS of Unit 2 of Daya Bay Nuclear Power Plant has been transformed within the overhaul period, with a total instrument and control transformation period of 98 days and successfully put into operation at the first test run. Practical results show that this technology can be applied to DCS transformation testing, realizing the goals of reducing the risk of on-site implementation, reducing the number of on-site debugging programes, and saving the duration of on-site implementation.