Development and prospect of microprocessor-based protection relays in China

During the last 10 years, microprocessor-based protection relays in China had been developing rapidly. Until now, three generations of microprocessor-based protection relay products had been developed. The third generation products are playing an important role in assuring the safety and normal operation of electrical apparatus and power networks and the fourth generation protection relays are being developed. The paper firstly reviews the microprocessor-based protection relays development history in China, and then briefly introduces the present development state of protection relay, including hardware system and protection principles or algorithms widely adopted in new protection relays. Finally, the paper describes the customer future demand and development trends.