English to Croatian Tech/Engineering Engineering: Industrial

XIII. GRID FREQUENCY CONTROL (GFC) WITH WATER WASH INJECTION (APPLIES TO UNITS WITH GFC REQUIREMENTS ONLY)

Several grid codes specify that at specific frequencies below normal, such as 50 Hz, gas turbine should remain at base load. During a severe under-frequency event, water wash injection may be used to reduce the net over firing of the gas turbine to conserve hot section life. The use of water wash injection to comply with GFC requirements depends on local regulation.

If water wash is used with GFC requirement, a GFC circuit is installed parallel to the on-line wash circuit so that both circuits are supplied simultaneously by the water wash skid. During a severe under-frequency event, two control valves are commanded open, water wash pump starts and water flows through both the on-line wash circuit and GFC circuit for a specified time duration. To maximize system reliability, a self-test of the GFC circuit is performed for a few seconds every ten on-line compressor wash sequence.