In dispatcher training simulation system (DTS), accuracy, timeliness and convenience maintenance are important evaluation indexes of relay protection simulation. The current mainstream simulation of protection have two ways that are fixed value judgment and logic judgment, both have their advantages and disadvantages, and application scenarios are also different. Under the background of multistage scheduling and control integration simulation in China Northern Power Grid, which has particularly complicated network frame and protection control. In order to ensure the timeliness and accuracy of protection simulation training system, the paper brings to fixed value simulation technology with logic judgment. The research results show that the simulation technology have widely application and good reliability, which can adapt itself to requirements of protection in DTS system for grid simulation.