Steam Turbine Control SystemRetrofits
Existing Instrumentation - In most cases the existing instrumentation on the turbine can be reused. No expensive electric valve upgrades are necessary since the system accepts OEM supplied LVDTs and servos. Turbine Diagnostic Services, Inc. (TDS) can retain any level of redundancy in the instrumentation supplied by the OEM including LVDT, servo coils and magnetic pickup inputs.
Inlet Pressure Control - TDS has implemented algorithms designed to control the inlet pressure to the turbine. This is the preferred mode of operation as it will control drum pressure and stabilize the level. The turbine will use as much steam as is available from the boiler. This mode also maintains peak steam turbine efficiency. When several turbines run in parallel the integral action of the controller will be disabled to allow the turbines to co-exist.
Initial Pressure Loss Control - TDS has implemented control algorithms to implement a Rate-Sensitive Initial Pressure Loss controller. This type of control forces the valves shut when the boiler pressure is decreasing at an accelerated rate. This is typically the result of the boiler loosing fire. During these conditions, there is an increased chance of water induction; therefore, the valves should close.
Extraction Pressure Control - TDS has implemented control algorithms necessary to implement extraction pressure control. This includes single and double automatic extraction control. The operator is able to control the pressure at the extraction and also implement a flow limit. The flow limit is implemented as a % of theoretical extraction flow. This scheme is fully integrated into the V1 control so that changes to V1 are feed-forwarded to the V2 & V3 valves in order to have a zero effect on extraction flow and pressure.
Admission Pressure Control - TDS has implemented control algorithms to control admission pressure. This algorithm can be combined with extraction pressure control to create admission/extraction control on machines that feature this type of control.
Exhaust Pressure Control - This type of algorithm is implemented on machines that are being used as letdown stations. It will control the pressure of the header (turbine exhaust) that it is discharging into. The integral action of this controller can be disabled in case there is more than one device controlling the pressure in the header at any point.
Speed Control - This type of control is implemented as a straight proportional controller with integral action when offline. The operator (or auto-start sequence) can input a speed target and ramp rate to instruct the control system to provide the desired speed and acceleration. This controller is the primary overspeed protection for the turbine and meets IEEE requirements.
Load Control - This type of controller is the default controller when the turbine is online. It is open loop control and is calibrated as percent of theoretical output. All control systems are equipped with this controller.
Megawatt Control - This controller is a closed loop load control. The feedback can come from a variety of sources. It can be a dedicated transducer (4-20mA) or from a digital protection relay that features Modbus communications.
Copyright © 2017 - Turbine Diagnostic Services, Inc.. All rights reserved
13447 Byrd dr., odessa, fl 33556
Fax: (727) 375-8710
24/7 service: (813) 969-0972
Toll Free: (877) 969-0972