Research On Optimal Power Flow Calculation Of Power Grid Considering Discrete And Continuous Decision Variables

Uncertainty and intermittency of wind power output will cause the dynamic operation process of the power grid to become complicated.In the calculation of Optimal Power Flow of the power system,we not only need to consider the static constraints but also need to consider the unit climbing constraints.In practical problems,the discrete characteristic of on-load tap-changer taps makes the dynamic optimal power flow problem into discrete and continuous variables mixed nonlinear programming problem,have yet to find effective method can be accurate to solve such problems,so dynamic optimal power flow calculation which contain wind farms is a problem worthy of studying.In order to establish an optimal power flow model containing wind farms,three common types of wind power generators are briefly introduced in this paper.Because of the low efficiency and complex model of the asynchronous wind power generators,the objective of this paper is to establish wind farm model by using synchronous wind turbines as the research object and further establish a system based on the system power generation cost and network loss cost as the objective function,considering the bus power flow balance and unit climbing constraints such as dynamic optimal power flow model including wind farm.Based on the above research,this paper establishes the DC optimal power flow model with the system power generation cost as the objective function,considering the power balance of the bus and the constraint of the unit climbing in the node power balance constraint,the complex continuous decision variable—network loss,is added to the system by the B-coefficient method to make the model more realistic.In order to decrease the difficulty of solving,the bus balance constraints of the system is linearized by using the Taylor formula,a quadratic programming model of the dynamic optimal power flow is obtained,and within a certain 26 bus system has carried on the simulation results,verify the effectiveness of the proposed model and method.Since the above simplification method is not suitable for solving the dynamic optimal power flow model considering discrete and continuous decision variables,this paper proposes to apply the generalized Benders decomposition to the solution of the problem: First,establish a system of power generation cost and loss cost as objective function,considering the dynamic optimal power flow model with different reactive output constraints of the wind farm,modifies the model by analyzing the discrete decision variables and the operating characteristics of the system;then,a generalized Benders decomposition is put forward for solving discrete and continuous decision variable optimal power flow method.The method decomposes the original problem into the main problem and the sub-problem.The main and sub-problems are solved byiterative genetic algorithms respectively.Finally,the proposed model and method are simulated in the IEEE-30 bus standard example to verify this paper,and the speed and effectiveness of the proposed model and method are verified.