Dynamic optimisation of a boiler-turboalternator model

Optimal control of a combined boiler-turboalternator model is developed using a discrete linear representation of the interconnected system. The boiler model is assumed to consist of lumped energy-storage elements, and it is combined with the turbine using flow-power relations associated with static operating characteristics. The turbine model includes the effects of steam storage in the reheater and inlet-valve chest, and it is coupled with an alternator model based on a linearised form of Park´s equations. Integrated control of fuel, feedwater, valve position and alternator-field excitation is developed, using the concept of dynamic programming to solve the single-point boundary problem. Integral action related to measurement of selected variables is also included within the optimal controller, and performance is compared with conventional three-term control of the overall model.