Research On Optimal Load Dispatch Based On Dynamic Coal Consumption Model

To improve the operating flexibility of coal-fired units is an effective way for our country in the future to solve the problem of large-scale renewable energy integration in grid.Optimal load dispatch system and using the heat storage of units themselves are keys to improve the speed and depth of peak shaving.There are great differences between transient conditions and stable conditions on the energy consumption characteristics of ultra supercritical units.Considering the influence of heat storage in transient conditions,models to calculate coal-consumption and heat storage of work substance and metal under transient conditions were established with lumped parameter method.The impact of work substance and load liters rate on heat storage was analysed qualitatively.The process of a transient test of a 1000 MW unit was calculated and analysed.Curves of heat storage and standard coal-consumption increment in the test were obtained and the distribution of heat storage was analysed.The model of optimal load dispatch was established based on the dynamic coal consumption model,through which not only the optimal strategy of load dispatch but also the optimal load liters rate was obtained.Results illustrate that the total heat storage rate almost has the same variation trend with the metal heat storage which is 1.5~2 times as much as the work substance heat storage;the water wall shares the largest propotion in the work substance heat storage while the superheater shares the least propotion;affected by heat storage,the standard coal-consumption increases 3.48g/(k W·h)during loading up and decreases 3.2g/(k W·h)during loading down;the average power supply coal-consumption of the plant decreases 1.58g/(k W·h)using dynamic coal consumption model instead of steady coal consumption model.This paper can provide reliable reference for further research on optimal load dispatch and load liters rate during load shaving.