Optimal Scheduling Of Combined Heat And Power System Considering Thermal Inertia And Price Constraints

As one of the main forms of renewable energy power production,the installed capacity and penetration rate of wind power is increasing rapidly in recent years.However,the ‘heat driven mode'of CHP units in northern China has brought a lot of pressure on wind power accommodation.In this thesis,the dispatching problem of combined heat and power system with high proportion wind power accommodation is studied considering the temperature delay and its equivalent heat storage characteristics at the output and input of pipes,electric thermal storage and heat load.The quantitative model of adjustable characteristics of heat input based on the comprehensive relationship characteristics of thermal network is established.Based on the coordination and complementarity between the adjustable capacity of thermal energy and the wind power output characteristics of power network,the day ahead optimal scheduling model of electric heating combined system is established;This paper studies the influence of electrothermal price incentive based on the marginal cost optimization of electrothermal combined energy supply on the adjustable characteristics of energy input of thermal power network,and establishes a intraday dynamic optimization model of combined heat and power system based on price guidance.The main contents of this thesis are as followsFirstly,the main components of source,network and load in district heating system are analyzed.Considering the huge differences between thermal network and power network in transmission mode and time scale,combined with heat transfer theory and multi energy system optimization theory,the mathematical models of important parts in thermal system is constructed.In order to ensure the thermal balance in the combined system,the heat transfer characteristics from the source to the network and to the load are fully considered.The delay characteristic model of solid electric heat storage,the equivalent energy storage characteristic model of pipe network and the thermal inertia dynamic model of heating buildings including enclosure,cold air penetration and cold air intrusion heat consumption are established,which lays the foundation for the follow-up research.Based on the inertial model of thermal energy transportation,considering the fluctuation and uncertainty of wind power,the multi-dimensional uncertainty set is used to represent the wind power output.Aiming at the uncertainty of wind power,a hierarchical scheduling model based on robust optimization is proposed.On the basis of this model,the node method is used to establish the constraints of energy conservation and hydraulic balance in the thermal network,and the power system constraints are considered.With the objective of minimizing the total operation cost of the system considering the wind abandonment penalty,the robust optimal scheduling model of the combined thermal and electric system is constructed.By comparing with the traditional mode of "heat-driven",it is verified that the proposed model can improve the wind power consumption,ensure the power security and reduce the cost at the same time.On the basis of day-ahead unit commitment,aiming at the deviation between day ahead forecasted and actual wind power output,an optimal scheduling method based on bi-level optimization considering the interests of energy suppliers is established.Through the electricity price compensation mechanism,the output of units at the electrothermal coupling node is guided to absorb the abandoned wind.An upper-level optimization model is established,which takes the stable operation of the power system as the constraint condition and the minimum operation cost of the system with wind abandonment penalty as the objective.Taking the maximum profit of the unit which belongs to the lower-level thermodynamic system as the objective,the constraint matrix of the input-output relationship of the lower-level thermodynamic system and the optimization model of the lower-level thermodynamic system are established by setting the constraints of heat source and load node as the marginal conditions.In order to decrease wind abandonment and load shedding,the upper power grid will provide a lower price at the high wind power output time period,while the lower power grid will carry out arbitrage according to the price.In view of the large number of joint system parameters,an optimization algorithm based on real-coded quantum algorithm is proposed.Simulation results show that the model is effective for wind power consumption.In order to set the optimal price for the electricity and heat in the bi-level optimal dispatch method,referring to the node marginal price in the power market,the corresponding thermal power flow calculation model and the solving model of the node marginal price in the heat market are constructed.Aiming at the market mode of separation of generation side,transmission side and sales side in energy market,a bidding model including suppliers,power system and thermal system is established.In view of the unilateral trading mode of the joint market,this thesis studies the price mechanism of the supply side and the transmission side of the market.In the upper model,the overall benefit of suppliers is the largest,while in the lower model,the cost of power system and thermal system is the smallest.The price mechanism model can rationally analyze the economic behavior of suppliers in the market environment,and provide a way of thinking for the establishment of the heat market.