On Reliability Design Technology Of Digital Substation Protection System

Digital substation is a cutting-edge issue now. It represents the future development of power system substation. The key to ensure the quality ofthe user is to ensure the stable and reliable.Unlike the simulation technology, we have used a new digital technology and equipment calibration methods for digital substation. But how to ensure the reliability is still a key issue. In the context of the Expo substation, this paper will focus on the reliability design study of the key equipment—electronictransformer, merge unit, exchange, relay, optical fiber communication.1) For analysis and comparison of normal and digital substation, found the advantages of digital substation.2) Compared the advantages and disadvantages of the normal and electronic transformer. Analysis the error and reliability from the principle.3) Research the error trials of electronic transformer. Describe the requirements of the experiments.4) After the study, excluding the discrete noise impact on the accuracy of transformer.Verified the reliability of electronic transformers.5) Combined with the application examples, analysis the reliability of optical fiber communication network on relay protection system. Summarized the advantages from the sample loop to the DC control circuits.6) Research the calibration technology of digital equipment. For the difficulties on usingthe normal analog-based method to the digital devices, in order to ensure the reliability of digital equipment, proposed a new calibration technique.7) Established the fault tree model of digital substation relay protection system, using FCPN method to calculate the confidence of each component which composed the fault tree model. To find the key factors and components as an important reference on the analysis of fault system.Expo station has been put into operation for two years,the relay protection systems are running well, the action ratewas 100%. And there's no malfunction accident. Visible through the actual operation, it could proved that the digital substation relay protection systems are reliable.