Research On Coordinated Control Strategy Of Isolated Island Micro Power Grid

As the traditional mainland power grid to the island with transmission lines far,high cost,low reliability characteristics,at the same time,the island has abundant renewable resources,an important measure to promote the stable development of island economy is to establish a stable and reliable island micro grid.In order to realize the security,stability and economical operation of the island micro power grid,and for the distributed power generation unit problems,the specific content of this thesis are as follows:This thesis first introduces the research status of micro grid,and the Tuoji Island is studied.Then,the photovoltaic power generation system is studied in depth,and the maximum power point tracking(MPPT)is carried out by using DC / DC method.For the impedance can only be unidirectional conversion.This thesis uses the improved particle swarm optimization algorithm for MPPT control,which is validated by simulation.Secondly,the wind power generation system is studied to understand the typical wind power generation form,the original wind turbine of Tuoji Island is improved.The control strategy of the pitch angle is used in the case of wind speed exceeding the rated wind speed.So that the output power of the unit quickly maintained near the rated power,the simulation results can be seen that the method control effect is good.As the photovoltaic,wind and other power generation units with random and intermittent characteristics,likely to cause instability of the DC bus voltage,this thesis use in the battery and super capacitor dual energy storage control strategy based on the proposed a group of batteries in a discharge state.To maintain the DC bus voltage stability method,and can quickly suppress its fluctuations.Finally,a hybrid control method of PDFI(proportional delay feedback integral)control and fuzzy control is proposed to study the grid-connected inverter,which can not only suppress the harmonic of the power grid,but also can quickly and accurately track the grid reference current,simulation shows that the method has a good control effect,effectively improve the power quality.