Operation of synchronous generator LOE protection in the presence of shunt-FACTS

• The impact of STATCOM/SVC on synchronous generator LOE protection is investigated.
• Presence of STATCOM/SVC causes a delay on relay operation.
• When loss of excitation is partially, STATCOM/SVC caused under-reach of the relay.

This paper deals with the impact of shunt-FACTS devices on the synchronous generator loss of excitation (LOE) protection. Considered shunt-FACTS devices in this paper include the static VAR compensator (SVC) and static synchronous compensator (STATCOM). The SVC has been modeled by thyristor switched capacitor (TSC) and thyristor controlled reactor (TCR) branches. Also, 48-pulsed converter is used to model STATCOM. The LOE relay considered in this paper is a negative offset mho distance relay containing two zones. It has been shown that injected reactive power of by shunt-FACTS devices prevents from the generator voltage drop during LOE, which causes the operation of LOE relay to be delayed. It has been also shown that when an incomplete LOE occurs, the presence of shunt-FACTS devices leads to under-reach of the relay. In this paper, various operational conditions of the power system and shunt-FACTS devices have been surveyed to authenticate the results.