Modeling And Energy Flow Optimal Dispatch Of Combined Natural Gas,Cooling,Heating And Power Campus Microgrids

The technology of combined natural gas,cooling,heating and power campus microgrids is an important aspect of the practical application of multi-energy complementary and coordinated utilization technology.As an integrated energy system,electricity,gas,cold,heat and other energy sources are coupled and interact with each other.The interconnected and coordinated operation of multiple energy sources can effectively improve the economic and environmental benefits of the operation of the entire microgrid,suppress the strong randomness and volatility of clean energy generation,greatly improve the reliability of energy supply of the integrated energy system,which contributes to the cascade utilization of energy and multiple energy sources,and makes it widely used in the energy supply of emerging industrial parks.In view of this,this paper takes the combined natural gas,cooling,heating and power campus microgrids as the research object,and studies the detailed modeling,multi-energy flow calculation method and optimal operation dispatch algorithm of the combined natural gas,cooling,heating and power campus microgrids.A decoupled method for energy flow calculation of combined cooling,heating and power(CCHP)microgrid is proposed.Components inside the energy station are modeled more detailedly,the energy coupling relationship between gas generator and cooling/heating equipments,as well as the power consumption characteristics of the circulating water pumps in the cooling and heating network are considered.According to the characteristics that in the CCHP microgrid,coupling relationship lies only in the energy station and loads,and the intermediate cooling network,heating network and power network are independent,the calculation can be decoupled into four parts: cooling network energy flow calculation,heating network energy flow calculation,power flow calculation and energy station energy flow calculation,and the back/forward sweep method is used for cooling/heating networks energy flow calculation according to their radial structure,which can reduce the computational complexity of the model and accelerate the calculation speed.A CCHP microgrid of an industrial park is taken as an example,and the results validate the correctness and effectiveness of the proposed method.A multi-period dynamic optimal dispatch model of the combined natural gas,cooling,heating and power campus microgrids is established.Taking the minimum operating cost as the objective function,it considers both the network operation characteristics of the cooling network,heating network,power supply network and gas supply network,and the influence of multiple energy storage devices including electricity storage,cooling storage and heating storage on the microgrid dispatch.Based on the scenario method,an optimal energy dispatching model of the campus microgrids considering the stochastic fluctuation of photovoltaic output is established,and the uncertain fluctuation of PV output is balanced by rapidly adjusting the stored power of the energy storage device.Taking a combined natural gas,cooling,heating and power campus microgrids as an example,the obtained microgrid operation dispatching scheme can effectively save energy consumption and reduce the operating cost of the microgrid;the coordinated operation of multiple energy storage devices can more effectively reduce the operating cost of the microgrid and help to suppress the uncertain fluctuation of photovoltaic power generation.Based on convex relaxation optimization theory,a mixed integer convex programming algorithm for optimal dispatch of energy flow in the combined natural gas,cooling,heating and power campus microgrids is proposed.Through the linearization processing technology,the Big-M method equivalent transformation and other processing methods,constraints with high nonlinearity is processed by convex relaxation,and the energy flow optimal dispatch of energy flow in the combined natural gas,cooling,heating and power campus microgrids is transformed into a mixed integer convex programming model which is easy to solve.The GUROBI solver in the mature commercial optimization software GAMS is used to solve the transformed optimization model quickly and reliably.Taking a combined natural gas,cooling,heating and power campus microgrid as an example,correctness and effectiveness of the proposed optimal scheduling model are verified.The operation cost of the optimal dispatching scheme is less than that of the mixed integer non-linear programming model,and the economic benefit is better.