Automatic control system (ACS)
This system controls all the turbo-compressor sub-systems from the start time of the unit. It also changes the control modes. Turbo-compressor control modes is changed considering the condition and speed of the unit. ACS is a whole integrated automatic control system based on S7 Siemens technology and all related auxiliary components for control & protection the gas turbine engine, compressor, Anti surge valve and all auxiliary systems.
ACS performs the following control and Protection functions:
- Governing control of GTE (gas turbine engine).
- Protection of GTE and compressor such as vibration protection, temperature protection, etc.
- Control function of start up and normal & emergency shut down sequence of TC.
- Anti surge prevention control.
- Control of auxiliary systems.
- Information, monitoring, diagnostics function of control system and instrumentation.
It controls the fuel control valve position which adjusts the speed of turbine and compressor. In fact, in operation modes, it’s the governor which controls the amount of injection fuel to combustion chamber and the gradient of turbine speed & temperature changes. The system of fuel regulation is intended for control of automatic starting and shut down, control of rotational speed of turbines to a target value set by the operator or a set point from ACS, for preventing emergency situation by limitation of the fuel feed in the combustion chamber of engine. The basic principle of system operation is control by means of negative feedback: the difference between the preset and actual parameter values is fed to the input of regulator and the output of regulator controls the actuating device. The purpose of control is stabilization of certain parameters of the engine with simultaneous monitoring of values of other parameters so that they were staying with in specified limits. For this purpose the system has a corresponding set of regulation loops, each of which is used for control of one parameter. The start of engine can be carried out either under the program or under control by feedback with use of chosen set of loops ,or a combination of this methods can be used.