The Application Of B Method In The Reliability Design Of Substation Real-time Control System

With the speedy development of electric power system, automation system is applied widely in power substation. Microcomputer protection system which is based on computer control technology, communication technology and electric power automation devices is the core of automation substation system. This system overcomes many defects including bad function of normal electric power system, poor reliability and ill management, etc. Then it makes the unattended system come true. Electric power system demands very high reliability since it needs to supply electricity safely to total electric net. B method is one of the formal methods, which are widely applied in industry now. It is based on analysis and verification of practical operations, so it can ensure the correctness of model design and the reliability of system functions.In the background of substation real-time control system, this paper finishes the design and implementation of system model using B method to improve the system reliability. First, the specification mechanism of B method, the verification theory and the developing process are presented, and then the advantages of improving the reliability for system by using B are obtained. Second, the background of substation system is introduced, and the function of microcomputer protection system is designed as follows: selective current fast tripping protection, the over-current protection, the over-voltage protection, the low-voltage protection, Bus bar Auto-closing protection, etc. Through analyzing these functions, the model of every unit in this distributed system is designed in B. Meanwhile, considering the accuracy of the fault locating, the models of protection functions which rely on the collaboration of units are established. Third, according to the idea of layer-based construction of B method, refinement is executed. To ensure the reliability and correctness of system, fault-tolerant and verification are presented. Finally, the design of software is translated into program language using B-Tool, which reduces the mistakes of program greatly.