Electric Water Heaters Participate In The Dispatching Control Strategy Research Of Electric Demand Response

Nowadays,the huge energy demand and environmental problems caused by fossil energy consumption have become the main factors restricting social development,and renewable energy technologies has become the key to solving this problem.However,the uncertainty of renewable energy generation impacts the power system reliability and increases safety risks.In the context of the smart grid,using dispatchable resources,demand response(DR)can effectively suppress renewable energy fluctuations and benefit for peak-load-shaving and valley-load-filling.Electric water heater(EWH)is important DR resources.However,compared with other household appliances,EWHs have faster response speeds,more complex thermodynamic characteristics,and users have higher requirements on comfort when using them.Therefore,it is of great practical significance to study EWHs load cluster while taking into account the users' economic needs and comfort requirements during the implementation of DR programs.Taking EWH as the research object,this paper proposes a piecewise linear approximation method for the nonlinear thermodynamic model,and an optimal scheduling strategy for EWHs.The main works of this paper are shown as follows:(1)The research background of this paper is introduced.In order to meet the supply-demand balance and ensure the stability of the power system,the demand side resources are used as the dispatchable resources.Optimal allocation of thermostatically controlled loads(TCLs)is helpful to realize two-way interaction between power companies and users.The paper points out the importance of studying the thermodynamic model and establishes an optimal electricity usage strategy,briefly introduces the current status of research at home and abroad,and clarifies the research content.(2)The energy flow relationship is analyzed to obtain the complex nonlinear thermodynamic function in the tank,and then the relationship between the current tap water temperature and the water flow rate is obtained according to the the thermostatically-controlled automatic water mixer.The large M method is used to introduce auxiliary variables to deal with the nonlinear thermodynamic relationship,and the thermodynamic linear relationship of EWH is obtained.The key influencing factors are determined based on the thermodynamic model,and the aggregation model is constructed based on Monte Carlo method.(3)This paper proposes a flexible control scheme that takes the user's economic needs and comfort requirements into account.According to the electricity price incentive signal,this paper considers two types of goals that users must consider while participating in DR: electricity cost optimization and user comfort optimization.In addition to power and temperature constraints,switch on/off signal constraints and minimum time for continuous heating and closure constraints are also included.Genetic algorithm(GA)and mixed integer linear programming method(MILP)are adopted in order to solve the multi-objective optimization problem.Simulation results verify the effectiveness of the proposed piecewise linear approximation method.(4)The simulation software is used to verify the multi-objective optimization model of EWH using different algorithms.Simulation results show that the linear thermodynamic model obtained by the piecewise linear approximation method proposed in this paper can accurately reflect the water temperature curve.The mixed integer linear programming method can more efficiently deal with the multi-objective optimization model,which is of great significance to solving the EWHs load cluster dispatchable problem.