| In order to alleviate the trouble of energy shortage in China, we must gradually reducedependence on fossil energy and vigorously develop solar energy, wind energy, tidal energy andother renewable energy to increase renewable energy consumption proportion in our countryenergy consumption composition. Due to the operation mode of micro grid is very flexible,micro-grid can implement with the grid connected operation and supply reliable support forpower grid. Micro-grid can also disconnect from power grid to implement islanded operation,ensuring the stability of the power supply of internal important load, so micro-grid get fasterdevelopment in China. But the smooth switching of two micro grid operating mode have a greatinfluence on security and stability operation of micro-grid, so the micro grid smoothing control isthe main part of micro grid control technology. This paper based on doubly-fed wind powersystem, energy storage system, low electric storage heat equipment, photovoltaic powergeneration system of micro-grid as the research object and this paper deeply study micro-gridsmooth switching control strategy in the two kinds of operation modes.Firstly, the mathematical model of wind speed, converter, wind machine, doubly fedinduction generator in doubly-fed wind power generation system, photovoltaic power system,energy storage system, and the simple equivalent model of low electric storage heat equipmentare established.Secondly, over/under voltage, high/low frequency detection and current injection islandeddetection method and peak valley operation mode and non-peak valley operating mode in powergrid connected operation are adopted in this paper. Due to the disadvantages of existing micro-grid control strategy, this paper design a energy storage controller including power controller,voltage regulator, current regulator and synchronization controller, gives the mathematical modelof each controller, and expatiates the whole control strategy of energy storage controller in micro-grid switching to each other among the process of two kinds of operation mode.Then, a micro-grid system simulation model which mainly consists of battery, doubly fedwind turbine, photovoltaic cells and low electric storage heat equipment is setted up inMatlab/Simulink platform. The simulation result indicates that the energy storage controller canmake grid connected inverter maintain voltage and frequency stability in micro-grid switching toeach other among the process of two kinds of operation pattern, ensuring the reliability of powersupply and providing electricity which conform to the national power quality standards Thesimulation result demonstrates that micro-grid operation pattern control strategy combining power ring, filter inductor current loop and filter capacitance voltage loop and synchronizationcontrol is effective.Finally, this paper is validated in shenyang hao cheng electric limited company“Distributed energy efficiency factory" project. The engineering experimental results indicatethat micro-grid operation pattern strategy combining power control, filter inductor current controland filter capacitance voltage loop and synchronization control is safe and economical. |
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