Optimal Scheduling Of The Combined Heat And Power Systems Considering Peak-regulation Ancillary Service Market

Due to the rapid development of the renewable energy industry in China,relying solely on the electric power system to integrate renewable energy is stuck in bottleneck.Improving the utilizaiton of renewable energy,especially wind energy,is an urgent problem.Faced with this problem,the integrated energy system has become a new breakthrough for promoting the renewable energy integration,and has attracted extensive attention from scholars over the world.Basing on the temporal and spatial distribution characteristics of the abandoned wind energy,this paper explores the method of better integration of wind energy from the perspective of combined operation of electric and heat power systems.The paper first analyzes the peak-shaving principle of the combined heat and power systems(CHPSs).Then,the technical principle of different measures for improving the peaking capacity of the CHPSs is introduced.The measures are divided into two parts: the direct measure for consuming surplus wind energy by electric energy storages;the indirect measure for enhancing the regulating ability of combined heat and power(CHP)units by heat storages or power-to-heat(P2H)devices.Morever,the economic benefits of electric energy storages,heat storages and P2 H devices are compared in details.The ranking of different devices are given according to the comparison.The intermediate variables in the traditional model of the heating system are simplified,and only the key parts that embody the energy storage characteristics of the heating system are concerned,including transmission delay?transmission loss?dynamic water temperatures and the thermal inertia of buildings.A ”source-load diret connected” model is proposed to describe the mathematical relationship between the heat source and the heat load,which is more suitable for constructing the optimal scheduling model of the CHPSs.A self-repair method incorporated with the real-coded genetic algorithm is proposed for solving the optimal operation problem.In the optimization process,not only the scheduling strategies of different units are embodied,but also the constraints are satisfied effectively.Case studies are carried out with a simplified six-node electric power system and a heating system with four primary heat stations.It is verified that the equivalent energy storage of the thermal power system plays a role in enhancing the peak-regulating ability of the CHSs,but it is still insufficient to enable the CHP units to achieve deep regulation.For the sake of higher demand for wind energy consumption in the future,it is still necessary to invest the additional devices for further consideration.According to the economic ranking of different additional devices,the heat pump(HP)which ranks the first is chosen for auxiliary heating.Basing on the policy of the peakregulation ancillary service market,this paper puts forward a new planning method on the HP capacity with the thermal power plant as the main body of the HP investment.The investment cost and operation benefit model of the HP are established respectively.In particular,the influence of the HP on the economic benefit of the thermal power plant in the peak-regulation ancillary service market is analyzed in details.The deep regulation income of the thermal power plant is formulated in five scenes which are classified in accordance with different levels of deep regulation required by power grid.The rationality and effectiveness of the capacity planning method are verified with the data of actual system.In addition,it is confirmed that under the peak-regulation ancillary service market,on one hand,the thermal power plant can obtain better economic benefit by allocating the HP,on the other hand,the improvement of wind energy utilization in the CHSs can be achieved.Based on the model established in chapter three,the optimal operation model of the CHSs with distributed HPs is studied.The on-off status of the HPs is generated by pre-judging the periods when the wind energy is aboundant,and the operating power of the HPs is controlled by the thermal power balance constraint and running constraint of the CHP units.In view of the policy of the peak-regulation ancillary service market,he objective function is rebuild by covering the benefit model of the thermal power plant in the peak-regulation ancillary service market and the operating cost model of the HPs.In addition,the constraints related to the HP are expanded and updated.Finally,the Benders decomposition method is applied to solving the optimal scheduling problem.Numerical case studies are conducted to corroborate the benefits of the HPs on releasing the regulating ability of the CHP units,increasing the operating benefits of the thermal power plant,and promoting the peak-regulation ability of the CHPSs for better integration of renewable energy.