Flexible Operation of Concentrating Solar Power Plant with Thermal Energy Storage Based on a Coordinated Control Strategy

Abstract

With the ambition of achieving carbon neutrality worldwide, renewable energy is flourishing. However, due to the inherent uncertainties and intermittence, operation flexibility of controllable systems is critical to accommodate renewables. Existing studies mainly focus on improving the flexibility of conventional plants, while no attention has been paid to the flexible operation of concentrating solar power with thermal energy storage (CSP-TES) systems. To this end, the ultimate goal of this work is to investigate the potentiality and realization of CSP-TES systems to flexibly operate in grid system regulation. With this goal, the dynamic characteristics of a 50 MW parabolic trough collector CSP plant with molten-salt-based TES is analyzed, and its dominant control characteristics are concluded to demonstrate the possibility of the ideal. After that, a coordinated control strategy is proposed. Specifically, a disturbance observer-based feedforward–feedback control scheme and a feedforward–feedback controller are designed, respectively, for the solar field and the energy storage subsystems, while the power block subsystem is regulated by a two-input and two-output decoupled controller. Based on the decentralized structure, three simulation cases are, respectively, performed to testify the capacity of the CSP-TES system to wide-range load variation tracking, strong disturbance rejection, or both. The results show that the CSP-TES system can adequately track the grid commands based on the proposed coordinated control strategy, even under strong fluctuation of irradiation, demonstrating the flexibility of CSP-TES participating in grid regulation. In the context of continuous penetration of renewable energy into the grid system, research on the role transition of the CSP-TES system from its own optimization to grid regulator is of great importance.

Keywords

• concentrating solar power plants
• flexible operation
• control strategy
• disturbance rejection