Research On Optimal Dispatching Of Gas-Electric Interconnected Integrated Energy System Based On Piecewise Linearization Of Weymouth Equation

With the development of multi-energy systems,the integrated electricity and natural-gas energy system receives more and more attention.Compared with the traditional smart grid,the two energy sources are tightly coupled and mutually complementary,which can realize the cascade utilization and coordinated optimization of energy.However,the interconnected relationship between the two energy systems poses a great challenge to the stable operation of the power system,and it also sharply raises the difficulty of optimization and scheduling of the integrated energy system.Based on this,in the context of gas-electricity coupling,aiming at the optimization scheduling problem of the integrated electricity and natural-gas energy system,the main works of this thesis are shown as follows:Firstly,aiming at the problem that the Weymouth equation is non-convex and non-linear,this thesis proposes the integrated electricity and natural-gas energy system optimization scheduling model based on the Weymouth equation piecewise linearization.To ensure the economics of IEGS operation,this thesis establishes the objective function of the model.Then it adds power system constraints and natural gas system constraints,and establishes the coupling relationship between the two systems.For the Weymouth equation,this thesis compares some existing piecewise linear approximation for IEGS scheduling problems and proposes a modification one-dimensional approximation method that achieves both fast-processing and high-accuracy.Testing results verify the effectiveness of the proposed method.Secondly,on the basis of using proposed modification method to linearize the Weymouth equation,integrated electricity and natural gas energy system optimization scheduling model considering multi-energy storage systems is proposed.The thesis adds electrical energy storage systems to the power system,adds gas storage tanks to the natural gas system,and considers the multi-temporal process to establish constraints.Testing results verify that integrated electricity and natural gas energy system optimization scheduling model considering multi-energy storage systems can reduce online generators,natural gas consumption and cost.Finally,similarly,the thesis uses proposed modification method to linearize the Weymouth equation.The existing reserve scheduling approaches for integrated energy systems need iterations of calculation to guarantee the feasibility of the gas-fired units' reserve,leading to problem of high computational burden.In this thesis,a two-layer optimization scheduling model of integrated electricity and natural gas energy system considering the feasibility of gas-fired units' reserve is proposed to set the boundary of the gas-fired units' power and reserve,so that the scheduling result can meet the gas network constraints.The proposed two-layer optimization framework can avoid repeated loop iterations,resulting in low computational complexity.Testing results verify the effectiveness of the proposed method.