Optimization Of Operation Mode Of Active Distribution Network

With the rapid progress of modern society,various industries become more and more dependent on energy,in recent years,the emergence of the energy crisis,so that people's attention to new energy.The access of a large amount of new energy makes the traditional distribution network gradually evolve into a controllable active distribution network.It is one of the characteristics of active distribution network to coordinate controllable resources by effective means.To optimize the operation mode of active distribution network,the operation plan of distributed power supply,reactive power equipment and energy storage equipment can be reasonably arranged to improve the operation efficiency of distribution network.In order to solve the problem,it is a study of the model and method of the distribution of the power grid,the structure of the power grid,the equipment and the control of the resources.The research content of the thesis mainly includes:(1)The principles of several typical power flow calculation methods for distribution network operation optimization are introduced:forward and backward substitution method,branch impedance method,Newton method,quasi-newton method.The general method of constrained nonlinear optimization is described in detail,and the active and reactive power coupling mechanism of distribution network is analyzed.Finally,the general model of active and reactive power optimization of distribution network is established.(2)An optimization model of the day-ahead operation mode of active distribution network considering many types of distributed power supply and regulating equipment is established.Aiming at the lowest cost of operation of the distribution network nowadays.More types of distributed power supply and regulating devices are considered:photovoltaic power generation,wind power generation,biogas power generation,garbage power generation,energy storage equipment,controllable load,the reactive power output of SVC,transformer gear,shunt capacitor.(3)The solution algorithm of the correlation model is established.According to the characteristics of continuous variables and discrete variables,and the optimization of the whole process is divided into four modules to solve alternately to achieve the optimal.The operating state and continuous variables of adjustable transformer tap,shunt capacitor are treated in different ways.For continuous variables,an extended Lagrangian function is constructed and solved by quasi-Newton method.After the switching state of shunt capacitor banks is identified,the first-order sensitivity of reactive power injection of capacitor nodes is arrayed by the objective function,and then the iterative solution is obtained,and the tap position selection of transformer tap is calculated by enumeration method,and for the adjustment of day-ahead state of discrete variables,combining with the changing characteristics of load curve,the tap position of peak segment is tried to be reduced and that of valley segment is raised.And four kinds of calculation are carried out alternately.(4)Taking the 118-node system as an example,by the method of optimization,the program is programmed to optimize the calculation,and the example analysis,and it is feasible and effective to separate discrete variables and continuous variables.After the optimization of the algorithm,the distribution cost is effectively improved.Thus,the practicability and feasibility of the optimization algorithm proposed in this paper are verified.