Programmable Logic Controller (PLC) Based Turbine Protection

Abstract

The turbine protection system protects the turbine from over speeding, monitors all critical turbine parameters, and trips the turbine if a condition exists that could cause equipment damage. The aim of this research is to use Programmable Logic Controller to protect steam turbines with capacity of 30 Mega watts in Khartoum North Power Station by using Siemens S7-300 controller, The existing turbine protection circuit consists of relays, contactors and resistor, and it operates more than 25 years. it has Only one common alarm for turbine trip, the alarm not define which circuits is tripped and which condition is occurring .This lead the maintenance and the troubleshooting of the circuit takes long time to define the cause of the trip signal and Also there is lack of spare parts. The existing trip signals are condenser water level extra high, condenser vacuum low, lubrication oil to bearing pressure low and electrical trip signal from generator protection this signal are digital signal. Additional analog signal added using the existing signal for turbine over speed, lube oil bearing temperature, bearing vibration and generator winding temperature. The software was written for Siemens S7 300 PLC using ladder logic language. And it consist an alarm for turbine trip and another one to define which signal cause the trip. Then it simulated by PLCsim.