ABSTRACT

Microprocessor digital protective relays (DPRs) are extensively displacing all other types of relay protection devices from the market since all the world leaders in this area have almost completely ceased production of all other types of protection relays for the electric power industry. Since the first introduction of DPRs in the electric power industry more than 20 years ago, these devices have caused considerable enthusiasm among specialists. Quite a number of articles have been published in the technical literature praising the benefits and advantages of DPRs in all aspects. However, as any sensible professional should know, an ideal technical device does not exist, and even the DPR has many technical problems and shortcomings that have already led to a significant reduction in the hardware reliability of relay protection1–4 and increased its cost. Since there is no alternative to DPRs today, we face a challenge to counterbalance the negative impact that DPRs brought into relay protection. In this chapter, I offer a new concept of DPR design capable, in my view, of solving many of the actual problems of DPRs.