A feedwater heater model intended for model-based diagnostics of power plant installations

Work related to the first-principle modeling of a feedwater heater operating in a coal-fired power unit is presented, along with theoretical discussion concerning its structural simplifications, parameter estimation, and dynamical validation. The objectives of this work are as follows: (i) formulate and deploy a moderately complex first-principle model of a feedwater heater to reproduce operational measurements in real-time simulations, (ii) develop a tuning method for this model, (iii) propose key indicators of heater performance using a model-based approach, and finally (iv) automate the calculation process of the indicators. A feedwater heater model is the main contributor to the performance of the entire simulation model of a power unit. In this work, the development process of such a model is presented, including necessary simplifications for improving its performance and functionality. As a result of the proposed simplifications, performance which allows operational data to be tracked by means of continuously updating model parameters in real-time mode was achieved on a regular PC workstation for a series of six low- and high-pressure heaters. The model variables (e.g. variability of the power rate of energy exchange) and estimated parameter values were used to formulate key performance indicators intended for a model-based diagnostics approach. Validation was successfully performed using operational data from a 225 MW coal-fired power unit.