Research On The Power Flow Calculation And Optimized Operation Of Distribution Network With Distributed Generations

With the supply of energy sources becomes emergency and more emphasis on the environmental protection. For the target of energy-saving and emission-reduction, we must develop the scientific technologies and low carbon economy, which is the road of electrical industry's sustainable development. Global industrial competition is already and the energy revolution is the core of the competition, developing smart grid is the inevitable trend of our country and the other countries. Through technology innovation in the process of generation, transmission, distribution, energy storage and consumption to reduce the infection to environment and enlarge the number of renewable energy connected into the distribution network. The concept of "low carbon economy" was firstly put forward in British government's white paper on energy in the year of 2003. For developing the "low carbon economy", energy-saving and emission-reduction is brought forward by our government, so the distributed generation technology attracts great recognition and gets rapid development.Less investment, flexibility, little pollution and efficiency are the advantages of distributed generations. With the development of the smart grid, there will be more and more distributed generations connect into the distribution network in the future. However, more distributed generations connect into the grid will have great influence on distribution network, whose structure and operation mode will be changed. Power flow calculation is an important means to quantitative analysis the influence on distribution network. On this base, the article analyzes the mode of distributed generation and combination interface, studies the calculation and optimization technique of the distribution network'power flow, discusses the impact on distribution network by distributed generation, and optimizes the power flow of distribution network with wind power generation. Chief research achievements are as follows.(1)For the power flow calculation of distribution network with kinds of distributed generations can be done easily, the mathematical models of wind power, photovoltaic battery, fuel cell and miniature gas turbine are researched in this paper. The three-phase power flow calculation program of distribution network is designed based on the back/forward algorithm, which can handle PQ, PI, PV distributed generation node type. According to PV node types of distributed generation exists convergence difficult in the process of power flow calculation using back/forward algorithm, the corresponding solution is put forward.(2) In view of unbalance in three phases and weakly meshed characteristics of the distribution network, after distributed generations are connected into the grid, three-phase power flow for the weakly meshed distribution network with the distributed generation and the unbalance in power source, load and line are studied. Then, this solution method is validated using simulation example. What is more, to test the algorithm's performance, four kinds of experimental scheme are propounded to analysis the unbalanced three-phase power flow calculation of distribution network with wind turbines, photovoltaic system, fuel cell and micro turbines. The matlab simulation results show that the three-phase power flow calculation method can accommodate different kinds of distributed generations easily.(3) In order to quantitative analyze the influence on the static voltage stability of distribution network with different kinds of distributed generations, a comparative analysis has been done among wind turbines, photovoltaic system, fuel cell and micro turbines. Therefore, an instructive conclusion is formed about how to plan the distributed generations reasonably in the distribution network. Finally, the power flow of distribution network with wind turbine generators has been optimized. Of course, the optimization results are satisfactory, including reduce the distribution network loss, improve the amplitude of system node voltage, and promote the bearing capacity to load.