The Ovation™ expert control system offers Unit Coordinated Control (UCC) that provides a coordinated front-end control strategy that unites the boiler and turbine controls. Coordinated controls generate and regulate the setpoint for unit load (MW). The unit load setpoint or UCC MW Demand may be generated from local operator entry, remote increase/decrease contact inputs, or internally generated contingencies such as runbacks and rundowns.
Unit coordinated control manages unit load (megawatts) and throttle pressure by sending out parallel demand signals to the boiler and turbine control loops through the Boiler Master and Turbine Master M/A Stations, respectively.
The Boiler Master demand is used as a feedforward signal to the feedwater master (controlling feedwater flow) and to the firing rate master (controlling fuel and air flow) to improve unit response to load changes. There is a ratio function only between the Boiler Master and firing rate master. The feedwater/firing rate ratio station controls the long term final temperature by using the ratio function between the boiler and firing rate masters. The ratio function changes the relationship between the feedwater flow and firing rate, resulting in a change in final temperature. The spray valves control the short term final temperature.
The Turbine Master demand controls the turbine control valves by sending an analog output signal to the turbine controls. The operator interface to unit control is through a dedicated graphic and associated pop-up windows which may be accessed at an Operator’s station.
Features
- Provides a coordinated front-end control strategy that unites boiler and turbine controls
- Startup control including the transition from wet to dry mode
- Seamless control throughout all regions from subcritical to supercritical operation
- Sliding pressure for efficient operation at lower loads
