A dynamic model used for controller design for fast cut back of coal-fired boiler-turbine plant

Fast cut back (FCB) technology of thermal power plant can restore electricity supply quickly after electric grid fault is repaired. In order to optimize the control technology for FCB, it is necessary to establish an accurate and simple mathematical model for thermal power plant. In this work, a mathematical model of coal-fired boiler-turbine is built up, basing on the balance laws of mass and energy. The steam turbine bypass system, boiler feedwater system and feedwater heaters playing vital roles during FCB are emphatically considered. Model parameters are estimated by FCB field test under the condition of 100% economize continue rate (ECR) load and validated by FCB field test under the condition of 50% ECR load. The model can be used in the controller design for thermal power plant during FCB. Moreover, FCB simulation test for plant with turbine-driven feedwater pump is carried out, showing that it is likely to cause the drum water level out of safe range during FCB.