The Grid Connected System Of Multi-unit DC Series-connected Wind Generator And Its Control

With the rapid development of social economy and science and technology,the huge energy consumption has resulted in the depletion of fossil energy and the serious environmental pollution.Wind energy,as a kind of renewable and non polluting new energy,has great potential for development.At present,the utilization of wind energy has gradually transferred from land to sea,how to build a large offshore multi-unit DC series-connected wind farm has become a hot issue in many countries.The wind energy utilization rate is reduced in the presence of the wind field in the multi-unit DC series-connected wind generator wind farm.In this article,based in the direct drive permanent magnet synchronous generator,the principle of discarded wind in the multi-unit DC series-connected wind farm wind system is analyzed.To construct the grid connected system multi-unit DC series-connected wind generator that does not produce discarded wind,a new system topology of multi-unit DC series-connected wind generator containing shunt circuit is proposed.The working principles and the control of the shunt circuit are analyzed,and the feasibility of the new proposed system by the comparative analysis of traditional multi-unit DC series-connected wind generator wind farm is demonstrated.Firstly this article introduces the world's energy and environment,analysis of the current wind energy utilization technology,introduces the topological structure of the current mainstream of large wind farms,and makes a thorough analyse of the advantage of the grid connected system multi-unit DC series-connect wind generator.And then analyzes the mathematical model of permanent magnet synchronous generator,expounds the concept of DC wind generator.A detailed analysis of the traditional topology of multi-unit DC series-connected wind generator wind farm is proposed,researches the principle of the discarded wind,and introduces the existing methods to reduce the discarded wind.Then,put forward a new grid connected system multi-unit DC series-connected wind generator system topology.The topological structure of wind farm contains a shunt circuit,the shunt circuit circuit can eliminate discarded wind phenomenon,improve the wind energy utilization rate.The shunt circuit comprises two power switches connected in series to form a half bridge circuit and an inductance.The midpoint of half bridge circuit is connected to the inductance.The shunt circuit leads to three output end which is connected in parallel with two adjacent DC wind generators.Finally,the Matlab simulation experiment is carried out on the grid connected system multi-unit DC series-connected wind generator that contains the shunt circuit.The function of the shunt circuit is verified.In the simulation,the input of the DC wind generator is researched,and the simulation of the the grid connected system multi-unit DC series-connected wind generator under the condition of unbalanced wind speed are compared and analyzed.The simulation results show that the grid connected system multi-unit DC series-connected wind generator that contains the shunt circuit can effectively solve the discarded wind problem.