Technical Study of Turbine Damage for Steam Power Plant

Damage to the turbine at the Steam Power Plant (PLTU) Bolok Indonesia began with a 70 kV Bolok - Maulafa conductor disturbance due to a lightning disturbance. All Diesel Engine Power Plants (PLTDs) in the Kupang system have a trip because there is an over current (OCR is working). PLTU Bolok has a trip due to under frequency (UFR is working). The electrical system (medium voltage and low voltage AC) at PLTU Bolok has a loss of power. Uninterruptible Power Supply (UPS) power distribution has a loss of voltage (loss of power). The turbine at PLTU Bolok were damaged at a very severe level, so that the casing was perforated due to overspeed beyond the allowable limit. The turbine overspeed occurs over the tolerance limit because the electrical and mechanical protection (functions to close the MSV and GV) do not work. The design that must be changed to reduce disturbance to the turbine caused by the GV system is the controller design for the GV and the logic design for operating and stopping the High Pressure AC Pump. Meanwhile, the design that must be added is the logic design for operating the turbine protection equipment.