A two-dimensional design and synthesis method for coordinated control of flexible-operational combined cycle of gas turbine

Abstract

The conventional combined cycle of gas turbine (CCGT) coordinated control strategy cannot quickly track the increasingly frequent and rapidly changing automatic generation control (AGC) commands due to the high penetration of renewable energy. In this study, a novel CCGT coordinated control strategy is proposed based on a two-dimensional design method consisting of time-scale decomposition and energy-flow coupling analysis. First, some critical design parameters of coordinated control, such as the power assignment ratios of gas turbine and steam turbine, and the energy storage coefficients of the heating networks are derived from energy-flow coupling analysis. Then, the AGC commands are decomposed into peak-shaving signals, low-frequency signals, and high-frequency signals from time-scale dimensional. As a result, a novel CCGT coordinated control strategy with precise dynamic heat-power conversion compensation is proposed and synthesized using distributed model predictive control to solve the large inertia, constrained, multivariable control problems. Simulation results show that the absolute integral error of the AGC tracking decreases to 1736 and the maximum ramping rate of the gas turbine is decreased by 20% without affecting the extraction steam flow under the proposed control strategy. All three indicators demonstrate the advantages of the coordinated control strategy designed by the proposed two-dimensional method.