Study on the dynamic characteristics, control strategies and load variation rates of the concentrated solar power plant

Abstract

As more and more wind power and photovoltaic power are connected to the electrical power system, it brings great challenges to the stability of power grid. Concentrated solar power (CSP) plant with thermal energy storage (TES) can undertake the task of load regulation and frequency regulation in power grid by balancing the electricity demand and generation. However, the maximum load variation rates of the CSP plant are not known, which restricts sufficient utilization of its advantages. In this study, a dynamic simulation model of CSP plant was built by using the APROS, and the dynamic characteristics were investigated by applying the step disturbances to molten salt flowrate, molten salt temperature, and the opening of steam regulating valve. Based on the results of dynamic characteristics, the control strategies were developed with the consideration of thermal storage in system and the feedforward signal of setting load and load variation rate. Then, the maximum load increase and reduction rates within different load ranges were studied. The results indicated that steam regulating valve, molten salt flowrate and molten salt temperature could be used to control turbine power, steam pressure and steam temperature, respectively. The designed control system could effectively follow the load variation with load deviation less than 0.3 MW and steam temperature deviation less than 1.2 °C in the condition of load variation rate at 3% Pe·min−1, which was superior to the conventional control strategy not considering the thermal storage in system. The maximum load increase and reduction rates were 11.57% Pe·min−1 and 8.94% Pe·min−1 within the load range of 75%THA-100%THA, and they were 10.42% Pe·min−1 and 7.46% Pe·min−1 within the load range of 50%THA-75%THA, respectively. The above load variation rates were first demonstrated for CSP plant, which could provide important guidance for plant operation in load regulation task and the load dispatching on grid side.