Abstract: Deep peak-shaving operation of thermal power unit provides an effective path to eliminate the stochastic disturbance on both power source side and transmission grid side, as well as to boost the renewable energy consumption rate. Meanwhile, the coordination control system of units also needs to be improved to ensure the control quality of power generation load-throttle pressure under the large variation of operation conditions. On the basis of simplified nonlinear dynamic model for typical subcritical units, the variation rule for the main parameters during the load shift process from rated load to deep peak shaving load is determined through the analysis on the basic principles. Then by combining classical PID parameter tuning method with simulation analysis, the optimal parameters of the coordination control system under main operation conditions are obtained and the control logic with variable parameters adapted to operation condition changes is proposed. The application of this method on deep peak adjustment retrofit has been implemented in a 330 MW unit. The optimized coordination control system can be automatically put into service within 33%~100% load range and good control quality is also achieved.

Key words: deep peak shaving, control strategy, optimization, variable parameter, simulation