ANALISIS GANGGUAN REVERSE POWER DAN UNDER FREQUENCY PADA GENERATOR 153,75 MVA UNIT GAS TURBINE 3.1 DI PLTGU GRESIK

Generator unit GT 3.1 at PLTGU Gresik which is operating in parallel with Sub Krian Gresik System failed at fuel supply on 06 October 2015 at 10:08 pm so that reverse power protection worked. The disruption resulted in the GT 3.1 unit stopped in operating for 2.21 hours. This research was conducted to find out how the disturbance and setting of reverse power relay in GT 3.1 unit and then the relationship between reverse power with under frequency and counter measures so that the reverse power interference on GT 3.1 unit does not happen again. In manual book settings applied, reverse power relay type 7RM3410 has a limit setting of 16% (16MW). Meanwhile, according to IEEE standard number 242 of 2001 reverse power relay setting of ∠ 50% and on generator unit GT 3.1 is still in the category allowed. When the 76.6% decline occurs due to disruption of the fuel supply, the value of EA = 1735.9 ∠ 31.98 ° V, and IA = 5750.26 ∠ 154.78 ° Ampere, the terminal voltage drops to 1035.88V while the system voltage is 10.5kV resulting in a reverse 17.2 MW. The power exceeds the applied setting, therefore the trip generator because reverse power relay work on setting time 1 second. At the time of interference, the rotation value of 702 rpm with a frequency value of 11.7 Hz. Setting the relay under frequency is 47.5 Hz lag time 10 seconds