IS200AEBMG1AEA GE MARK BOARD IS200AEBMG1A

The gas turbine fuel control system will change fuel flow to the combustors in response to the fuel stroke reference signal (FSR). FSR actually consists of two separate signals added together, FSR1 being the called–for liquid fuel flow and FSR2 being the called–for gas fuel flow; normally, FSR1 + FSR2 =FSR. Standard fuel systems are designed for operation with liquid fuel and/or gas fuel. This chapter will describe a dual fuel system. It starts with the servo drive system, where the setpoint is compared with the feedback signal and converted to a valve position. It will describe liquid, gas and dual fuel operation and how the FSR from the control systemspreviously described is conditioned and sent as a setpoint to the servo system.

 

If the hydraulic actuator is a double–action piston, the control signal positions the servovalve so that it ports high–pressure oil to either side of the hydraulic actuator. If the hydraulic actuator has spring return,hydraulic oil will be ported to one side of the cylinder and the other to drain. A feedback signal provided by a linear variable differential transformer(LVDT, Figure 13) will tell the control whether or not it is in the required position. The LVDT outputs an AC voltage which is proportional to the position of the core of the LVDT. This core in turn is connected to the valve whose position is being controlled; as the valve moves, the feedback voltage changes. The LVDT requires an exciter voltage which is provided by the VSVO card.