An optimized dispatch model of combined heat and power system unit commitment considering heating network characteristics

Abstract

The large-scale commissioning of combined heat and power unit leads to difficulty of peak regulation and wind consumption, and combined heat and power optimized dispatch is one of effective ways to solve this problem. Under existing optimized dispatch models of combined heat and power system, pre-decided unit commitment scheme may cause a large amount of wind curtailment because of excessive operating units and total minimum technical output of units. In view of these problems, through combination of unit commitment and optimized dispatch, an optimized dispatch model of combined heat and power system unit commitment considering heating network characteristics is established. Similarities and differences of heat and power energy transmission are analyzed, heat load partition balance equation as well as positive and negative spinning reserve constrains of thermal system partition are established, and influence of heating network characteristics, including time delay and heat loss, on unit commitment scheme and wind curtailment is studied. A numerical example shows that heating network characteristics influence unit commitment scheme (one unit shuts down an hour ahead and starts up an hour later). Besides, it shows that while meeting power and heat load demand, the model of this paper can timely start up or shut down units according to load change and spinning reserve demand, reduce total minimum technical output of operating units to 632.4 MW, and further improve wind power accommodation quantity to 3410.24 MW·h.