Research On Supply Power Quality Control Method Of Typical Micro Grid

In the remote areas or islands that the large power grid can not cover,the isolated microgrid is often used in the form of power supply in this area.Isolated microgrid power usually includes wind power,photovoltaic,energy storage systems and so on,and the renewable energy's fluctuant and intermittent output will bring serious influence to the power quality of the grid,which will result in higher power fluctuation of the net load(power difference between the power of the load demand and the output power of the renewable power supply).In this case,the energy storage system should be introduced to suppress the fluctuation quickly,and meet the needs of the net load,and ensure the reliable power supply of the micro grid.In this paper,a clustering method based on self-organizing mapping neural network is proposed to cluster the net load power of different isolated microgrids.The application of the self-organizing map neural network in the load classification is compared to cluster the net load power fluctuation curve of the isolated microgrid.Mathematical models of net load fluctuation for 6 different isolated microgrid scenarios are established.Based on this clustering method,the analysis of net load power curve is implemented.Finally,three self-defined performance indicators are used to verify the correctness of clustering results.In view of the active power fluctuation and intermittent of photovoltaic(PV)power systems,based on a hybrid energy storage system consisting of super capacitors and lead-acid batteries,an active power layered allocation strategy is formulated to optimize the output power of PV source based on the method of Variational Mode Decomposition(VMD).First,after the net load,undertaken by the hybrid energy storage system,is composed by VMD,the low-frequency component and high-frequency components are undertaken by the lead-acid batteries and super capacitors to smooth the fluctuations of output power of PV.At the same time,the orders of VMD filter are amended secondarily according to the state of charge(SOC)and the largest charge/discharge power in real time.In this paper,the typical scenarios of clustering results are given,and the appropriate energy storage system are configured for them,what's more,we also analyze the effect of energy storage system to stabilize its net load power fluctuation and optimize other power output environment.Offshore oil drilling system,which belongs to the first kinds of typical scenes,is configured the hybrid energy storage system or only the super capacitor to compare and analyze the different effect,and to verify the correctness of the net load clustering;the hybrid energy storage system is configured in the isolated microgrid scenario with photovoltaic power generation,which belongs to the second kinds of typical scenes.The simulation tests demonstrate that the method can effectively smooth the fluctuation of net load,and the optimization of regulation performance and long-term and stable operation of the hybrid energy storage system were realized.