Modeling and control method of combined heat and power plant with integrated hot water storage tank

Abstract

To enhance the flexibility of conventional power plants, a dynamic mathematical model of a combined heat and power unit is developed and verified in this study using field data, and the maximum relative error is less than 5%. Subsequently, the dynamic characteristics of the coal-fired power plant with the hot water storage tank are studied, and the temperature distribution curve inside the hot water storage tank is obtained. Finally, a new coordinated control system with an integrated hot water storage tank is designed. The new coordinated control system reduces the fluctuation in the heating load caused by the unit in the process of changing the load. The integral of absolute value of the error criterion and integral of time multiplied by the squared error criterion results for unit loads at different variable load rates are at least 200 and 50,000 lower compared to conventional control methods. This study provides a new solution to the problem that the current conventional turbine and boiler coordinated control system cannot address the difficulty of renewable energy power consumption, which is important for the safe and stable power grid operation after the large-scale grid connection of renewable energy power.