Dynamic modeling and control of direct air-cooling condenser pressure considering couplings with adjacent systems

Abstract

Direct air-cooling is considered as a promising technique in power generation because of its huge water-saving advantages. However, this is accompanied by inherent sensitivity to meteorological and ambient conditions, which is liable to cause frequent detrimental fluctuations in the condenser pressure and unit operation stability/economy. Therefore, a higher requirement has been imposed on the control system to achieve stable and economic operation of direct air-cooling condenser. To this end, a dynamic direct air-cooling condenser pressure model is first established in this paper after taking fully consideration of both condenser dynamics and couplings with adjacent systems. Then, two control methods, namely zone model predictive control and zone economic model predictive control are applied to the established model to realize zone control of the condenser pressure while suppressing control quantity variations resulting from time-varying ambient temperature. Detailed quantitative analysis of the influence of direct air-cooling condenser pressure on the turbine bleed flow and unit economy has been performed after both model steady-state and dynamic verification, and the comparative control simulation results under two typical cases have illustrated that the proposed zone economic model predictive controller provides a flexible way to simultaneously deal with the ambient temperature changes and economic optimization issues.