A manual/automatic synchronization circuit for a 37.5 MVA steam-turbine-driven generator

The critical parameters in synchronizing a synchronous generator to an electrical system are delta phase angle, delta frequency, and delta voltage magnitude. A manual/automatic synchronization circuit has been designed for a 37.5 MVA generator with protection for all three critical synchronizing parameters. The manual/automatic synchronizing circuit uses triple redundant protective levels for both the manual and automatic circuits. The first and second protective levels are shared by both circuits. These protective levels are a solid-state automatic synchronizing relay in tandem with a solid-state synchronisation check relay. An operator/synchroscope provides the third protective level for the manual circuit, while a microprocessor-based governor provides the third protective level for the automatic circuit. The philosophy, design, and operation of this manual/automatic synchronization circuit are reviewed