Plenary lecture 2: protective system reliability enhancement in smart power grid

The functional security of the power Grid depends upon the successful operation of thousands of relays that may be used in protective scheme for preventing the power system from cascading failures. The failure of one relay of the protective scheme to operate as intended may jeopardize the stability of the entire power grid and hence it may lead the whole system to blackout. In fact, major power system failures after a transient disturbance appearance are more likely to be caused by unnecessary protective relay tripping rather than by the failure of a relay to take action. In other words, the performance of protective relay or system is determined by several criteria including reliability, selectivity, speed of operation, etc. However, reliability which has two aspects: dependability and security is very important especially in smart power grid. Dependability is a degree of certainty that the protective relay will operate correctly when there is a fault in the power system. However, security relates to the degree of certainty that the protective relay or scheme will operate unnecessary when there is transient distribution in the power grid. Appropriate relay testing provides a first defense against relay mal-operations and hence improves power grid stability and prevents catastrophic bulk power system failures. Relay testing can help to validate the design of relay logic, compare the performance of different relays, verify relay settings, identify power system conditions that might cause unintended relay operation, and carry out post-event analysis to understand the causes of unintended or incorrect relay actions. Relay testing system improvements need to continue because of the use of relays in smart power grids where the conditions that are not the same as in the simple conventional one. In this talk we discuss new technologies that allow designing an enhanced relay testing system that can be used for improving the performance of protective relay. At the beginning, we present the different steps which may be followed in order to develop an enhanced relay testing system taking into count all conditions of the power grid. After that, we discuss how to improve protective system reliability, both dependability and security; using this relay testing system in smart power grid. We have already designed and implemented Microprocessor based relay testing system through the use of the new technologies such as microcontroller or PC associated with acquisition as well as we have tested its performances for showing its experimental evaluation. Besides, we have developed some relays where these advanced testing system have been used for evaluating their performances. We will end up this talk by presenting our research projects related to this subject.