Design and application of a steam temperature optimizer in a combined cycle

摘要

This paper presents the application of an adaptive predictive control system, entitled 'Steam Temperature Optimizer' (STO), in the combined cycle of the Empresa Nacional de Electricidad SA at Barranco de Tira-jana in the Canary Islands. This combined cycle comprises two gas turbines of 70 MW each, two recovery boilers, and one steam turbine also of 70 MW. The STO was applied to the control of the temperature of the high-pressure recovery boilers and integrated in parallel with the plant's distributed control system by means of object linking and embedding for process control communication. The STO control strategies, designed to deal with the specific attemperation control problems and plant instrumentation limitations, are presented and the experimental results analyzed in comparison with those obtained by the existing PID-based system. The STO improved significantly the control precision and the stability of the steam temperature and confirmed adaptive predictive control as a reliable self-tuning methodology for this kind of process.