The Research On Optimal Allocation Of Distributed Generation Access To Distribution Network

The main features of modern power system are focused on power generation, long-distance transmission, power grid interconnection. Such a centralized single power supply system has been gradually highlighting various drawbacks, which is both "fragile" and "clumsy". Small-scale power generation in a small place near the load power can compensate for the shortage of large-scale centralized power, which can effectively reduce network losses, save invest and improve power supply reliability and flexibility. So the distributed power supply has received more and more attention. However, improper access to distributed power system will bring bad effect for network loss, power quality, power distribution and so on. To reduce power loss and to improve the distribution network voltage quality, this dissertation analyzes the access of the distribution power network to the distributed power network.This dissertation first introduces the five main types of distributed generation, grid structures and mathematical models. This dissertation makes a unified procession of each node type to adapt for the calculation method of the traditional distribution power flow. The role and influence of the distribution network accessed to the distributed power grid are introduced. Based on the relevant standards and regulations, the author of this thesis proposes the requirements of a distributed power network accessed to the distribution network.Second, by comparing the flow algorithm of the traditional distribution network, together with changes in its structure and characteristics of the distributed power access to the distribution network, an improved flow algorithm based on forward and backward extrapolation of the distribution network is put forward. Combined with the node associated with the matrix grid topology, this calculation method introduces a calculation vector to determine the order of the branch to push forward and backward, effectively avoiding the analysis of complex network structures. This makes programming easier to implement. Finally, through an example simulation, the author verifies that the method can achieve flow calculation tasks of the distributed power quickly and accurately.Finally, the author establishes a distribution network with small node voltage offset losses. The author also establishes multi-objective optimization model. By comparing three mainstream kinds of intelligent optimization algorithm (the ant colony algorithm, particle swarm optimization and genetic algorithm), the author puts forward two particle swarm optimization and genetic algorithm), the author puts forward two improved genetic algorithm based optimization method, that is count VEGA algorithm and NSGA-II algorithm. By using two algorithms to solve the optimal allocation model of the distributed power network and by using IEEE33node cases system for simulation, the author verifies the correctness of the optimization model and the advantages of improved algorithm. Finally, by comparing the three aspects, the NSGA-II algorithm is much better than the VEGA algorithm when optimizing the location and the capacity of the distributed power grid accessed to the power generation network.Seeing from the simulation results, it can be seen that the proposed configuration optimization model of the distributed power network accessed to the distribution network can effectively reduce system losses and improve voltage quality, which is of great guide to the distributed power accessed to the grid network.