Stochastic Optimal Scheduling In Micro Energy Grid Considering Pumped-storage Unit And Demand Response

With the rapid development of energy field at home and abroad,the increasing energy demand and growing environmental pollution problems has become a great challenge to be solved for human society.However,as the second biggest economy in the world,China’s current energy model and consumption structure cannot meet the requirements of sustainable development.Therefore,improving energy efficiency and reducing harmful gas emissions are important ways to improve the current situation of energy in China.Recently,the concept of micro energy grid based on combined cooling,heating and power has provided new idea for solving energy problems in China.In the framework of multi-energy system,compared with the traditional micro-grid,it can not only improve the energy efficiency,but also realize the cascade utilization of energy to balance the contradiction between the increasing energy demand and sustainable development.(1)The concept and structure of micro energy grid are introduced,the energy hub model and energy supply structure of micro energy grid are described in detail,and the mathematical model of micro energy grid based on energy hub model is established.The energy hub can reflect the flow process of input,conversion,storage,transmission and output of many kinds of energy such as cooling,heating and power in the system.Then,two operation modes: off-grid and grid-connected modes are introduced.(2)Considering the uncertainty parameters in the optimal scheduling of the micro energy grid,analyzing the causes of the uncertainty,selecting the appropriate probability distribution function model for each uncertainty parameter,and generating several typical scenarios using the Latin hypercube sampling method and k-means clustering method,the calculation time is greatly reduced without losing representativeness.For better performance on the demand side,price-and incentive-based demand response programs are employed to reduce the operation cost and maintain reliability during the high load period.Due to the life cycle cost of pumped-storage units is remarkably lower than battery storage,pumped-storage units are selected as an alternative for electricity storage instead of batteries.To minimum operating cost and minimum emissions,a stochastic optimal scheduling model of micro energy grid considering pumped storage unit and demand response program is established.The coupling characteristics of the optimal scheduling of the micro energy grid determine that the model is a multi-objective and multi-constrained nonlinear programming problem.Therefore,a multi-objective artificial sheep algorithm is proposed to solve the optimal scheduling model.Compared with the traditional optimization algorithm,the superiority and effectiveness of the proposed algorithm are verified.(3)An improved residential micro energy grid is proposed in this paper.Then,three typical optimization scheduling models are analyzed: Grid-connected mode without implementing demand response programs,considering operation cost and emissions;Grid-connected mode with implementing price-based demand response programs,considering operation cost and emissions;Islanding mode with implementing price-and incentive-based demand response programs,only considering operation cost.The results show that the price-based demand response program can effectively reduce the operating cost and emissions,and energy storage can also flat the load curve and improve the stability of the proposed system.The price-based and incentive demand response programs can meet the user’s energy demand on the premise of reducing the operating cost.Through the comparison of each case,the effectiveness and feasibility of the proposed optimal scheduling model are verified,which provides a theoretical basis for the economic and stable operation of micro energy grid considering the pumped storage unit.