Turbine Protection by Using Microcontroller

Abstract

Protection of turbine generator systems is an important factor that has to be considered in power plant for efficient production of electricity. Turbine protection involves axial shift of turbine shaft, lubricating oil pressure and condenser vacuum. Axial shift measurement is very important to monitor the mechanical balance between the turbine and generator rotor. If there is any variation in the mechanical balance the turbine shaft will be damaged. The lubricating oil is used for the lubricating turbine bearings. It is maintained at the pressure of 1.2 kg/cm2. If the Lubricating oil pressure is reduced to below 0.6 Kg/cm2 the turbine bearings temperature will increased. The condenser vacuum pressure is considered for turbine protection because it is responsible for steam flow from low pressure turbine to condenser. Condenser vacuum is maintained at -670 mmHg. If there occur decrease of -540 mmHg, a back pressure is created in the Low Pressure Turbine and also Turbine efficiency is reduced. The existing system of protection in turbine generator system is relay and hard wired system. This system has lot of disadvantages such as high power consumption, slower operation rate, high maintenance cost, consists of so much of wires, improper operation at critical stage, is not safer, since using of dc supply. These disadvantages are eliminated by using PIC controller. PIC 16F877A is a controller which is used for the protection of turbine generator system. PIC controller operates at very low voltage and it consumes lesser power. It uses simple user friendly programming and reduces the hardware components. Program used in the PIC can be easily altered and effectively controlled. PIC IC is used for real time monitoring of data that can be done in relay system.