Inlet Guide Vane Control System Modification to Improve the Reliability of Gas Turbine

Inlet Guide Vane (IGV) is a component in Gas Turbines (GT) that functions as a place for air inflow to the turbine gas compressor. The function of IGV is to maintain an appropriate fuel-to-air ratio in various load of a GT which is related to exhaust temperature, a mandatory operating parameter of a GT operation. In 2020-2021, there were 11 force outages occurred caused by the IGV abnormal position with a total opportunity loss more than 2,789 GWh. The aim of this paper is to modify GT IGV control system to reduce force outages caused by the IGV abnormal position. On existing IGV control system, there is no logic in IGV system that is able to stop the movement of IGV that cause the abnormal position. The modifications were made by adding logic position feedback to the pilot oil pressure of 1 degree up the trip limit of the GT at 45 degrees, so that the GT does not experience a force outage and the GT operator can counteract by setting the GT at a minimum load, which is 70 MW. Based on the results of this paper, in 2022 there was no GT force outages caused by the Inlet Guide Vane abnormal position and there was no opportunity lost obtained. Thus, it can be concluded that the modification of the IGV control system that has been carried out can reduce force outages effectively and improve the reliability of the gas turbine.

I. Introduction

A combined cycle power plant combines the gas and steam cycles by harnessing the energy of the flue gas (FG) emitted by a gas turbine (GT). This flue gas is at a high temperature of around 550-650°C, which is the temperature normally reached in a normal steam power plant. Flow gases flow through a heat recovery steam generator (HRSG) downstream of the gas turbine, releasing heat to the lower steam circuit. A steam cycle can produce additional electrical or thermal energy. In the latter case, the combination of electrical energy from the gas turbine and thermal energy from the basic cycle is called cogeneration [1]–[3].