Total Load Supply Capability And Security Level Classification Of Integrated Power And Natural Gas Systems

Compared with traditional coal-fired power generation,gas-fired power generation has the advantages of high environmental value and fast start-stop speed.As the capacity of gas engine assembly machines increases,so does the coupling between power system and natural gas system,resulting in the normal or contingency of a single system that will affect and constrain the security of operation of another system.Therefore,in this paper,the security of the integrated power and natural gas systems is studied in depth.The main research contents are as follows:Firstly,the composition of the natural gas system is given,the differences between the power system and the natural gas system are compared,and the characteristics of the integrated power and natural gas systems are discussed.This paper introduces the optimization problem of integrated power and natural gas systems.The mixed integer linear programming used in this paper,YALMIP programming language and CPLEX toolbox are introduced,which lays a foundation for subsequent research basis.Then,the total load supply capability of the integrated power and natural gas systems considering normal and power system N-1 contingency is defined.Taking the gas turbine as the coupling component,considering the DC current flow of the power system and the steady operation of the natural gas system,the optimization model of the total load supply capability of the integrated power and natural gas systems is proposed.The nonlinear equations in the model are processed by the incremental linearization method,and the problem is transformed into a mixed integer linear programming form that can be efficiently solved.The models are programmed using the YALMIP language and is called CPLEX.Simulation examples verify the validity of the proposed concepts and models.Finally,the impact of contingencies on the total load supply capability of the integrated power and natural gas systems is measured by the load change rate and the contingency load rate.A method for dividing the security level of the integrated power and natural gas systems is proposed.The N-1 check is used to judge whether the integrated power and natural gas systems is secure to operate.If the N-1 check is not satisfied,IES load loss rate,threshold crossing,danger index and so on are used to measure the unsecure operation state;If the N-1 check is satisfied,based on the total load supply capability of the system,IES safety margin,power flow-gas flow index,comprehensive margin index are used to measure the secure operation state of the system.And the effectiveness of the proposed index and security level classification method is verified by simulation examples.