A new microprocessor-based protection and control unit is introduced, which considers the probability of both different frequency synchronization and same frequency synchronization during circuit breaker closing for power network connection. 介绍了一种新型的微机保护测控装置在实现同期功能的过程中,充分考虑了在断路器合闸时既有差频并网又有同频并网的可能。