Research on coordinated control system of drum boiler units considering energy demand decoupling

Abstract

This paper proposes a coordinated control system (CCS) of a drum boiler unit considering energy demand decoupling. Since there is large delay and inertia in the response from the coal feed flow to the main steam pressure, the generalized predictive control (GPC) algorithm is adopted to design the CCS. As the coupling between the boiler and the turbine is serious, an energy demand signal is constructed and integrated into the GPC controller to realize decoupling control of the unit. Based on evaluation rules, a load command signal is reconstructed to improve the adaptability of the unit to the grid. Simulation results show that the CCS can track the load command rapidly, overcome the nonlinearity and backlash of governor valve, and ensure the safe and stable operation of the unit. Application results show that the CCS performs well during load up, load down, and load swing. The performance indicator exceeds 4.0 for one month, and its maximum value is up to 5.09. Simultaneously, the unit maintains a high degree of stability, the overshoot of coal feed flow is almost zero, the fluctuations of steam pressure and temperature are small. Obviously, the proposed CCS is advanced and practical.