Dynamic Simulation Study on a Coal-Fired Power Plant Aided With Low-Temperature Solar Energy

The concept of coal-fired power generation aided with solar energy uses stable fossil energy to compensate the instability and intermittently of solar power and reduces the cost of concentrated solar power (CSP) by decreasing the large-scale heat storage and turbine systems of CSP. In this study, trough solar collector system (TSCS) was integrated into the low-pressure heater side of a 660 MW coal-fired power generation system. In the system in which the 6# LP heater is completely replaced by TSCS, the variation value of the steam extraction flowrate of the LP heaters and the turbine output power decrease with the reduction in loads from 100% to 60% THA, and the output power increases by approximately 1 MW under 100% THA. When TSCS completely replaces the 6# LP heater under the load of 75%, the effects of direct normal irradiance (DNI) increase and flow ratio decrease on the main operating parameters of solar-aided coal-fired power plant (SCPP) were studied. Results show that the step increase of DNI decreases the 5# steam extraction flowrate and increases the output power by nearly 3 MW. When the flow ratio decreases by 139.87 kg/s, the output power decreases by around 0.35 MW. The dynamic characteristics of SCPP under different parallel situations with the load of 75% were also studied. As the number of parallel stage increases, the decrement in 5# steam extraction flowrate and the increment in output power decrease. The response time also decreases. Our study aims to provide detailed references for the control system design and optimization of coal-fired power units aided with solar energy.