Optimal Dispatching Of Combined Heat And Power System Considering Source-side Flexibility Improvement And Flexible Heat-power Load

With the rapid growth of electricity demand,the increasing difference between peak and valley loads brings great peak regulating pressure to the power grid.Meanwhile,the anti-peak-regulation characteristic of wind power as well as the overlap between the peak heating period and wind power surplus period has aggravated the difficulty of peak regulation in northern China,which leads to weak capability of the wind power accommodation.Aiming at the wind curtailment problem in three Northern areas,this paper puts forward a source-load coordination operation scheme applicable to combined heat and power(CHP)system of “Three North” area,in which the dispatching of flexible heat-power load to promote the wind power accommodation is discussed on the basis of improving the source-side flexibility.First,based on the detailed analysis of the operation costs for three peak regulation stages of thermal power units,the operation cost model for depth peak load cycling of thermal power units considering low cycle fatigue life expenditure along with oil consumption is established,and the peak load regulation service compensation and allocation models are put forward in this paper.The influence of different compensation standards on the initiative for thermal power units to participate in deep peak-regulating is analyzed by a simulation.Following,the principles and economy of three different regulation range expansion methods of CHP units,including the installation of heat accumulators,electric boilers or heat pumps in CHP plants,are analyzed in this paper.The mechanism of the regulation range expansion method with heat accumulators to improve wind power accommodation is analyzed,and based on the analysis of the heat accumulator heat storage and release characteristics,the regulation range expansion of the equivalent CHP units with heat accumulators is modeled as well.The relationships between the effect of wind power consumption and heat accumulator parameters——including the capacity of heat accumulator,the upper limits of heat reserving and releasing,and the initial ratio of heat storage——are analyzed through a simulation example.Finally,the interruptible and controllable characteristics of the load-side peak-shaving electric boiler are analyzed,and the abandoned-wind-start peak-shaving electric boiler is considered as an interruptible and controllable electric and heat load.Regarding total operation cost least as the target function,this paper presents an optimal dispatching model of CHP system with the combination of3 wind power accommodation schemes,including regulation range expansion of CHP units,deep peaking transformation of thermal power units and installation of load-side peak-shaving electric boilers.This model has a strong applicability as it can be used to analyze and compare arbitrary combination scenes of 3 wind power accommodation schemes.The effects of the ratios of deep peak-regulating thermal power units and regulation range expansion CHP units on the wind power curtailment are analyzed through a simulation example.Research results show that the improvement of source-side flexibility through the regulation range expansion of CHP units and the deep peaking transformation of thermal power units can expand the space for wind power integration in CHP system.Moreover,the source-load coordination operation scheme with the combination of source-side flexibility improvement and flexible heat-power load proposed in this paper can efficiently relieve the peak regulating pressure of CHP system in “Three North” area,and further improve the wind power accommodation rate.