| Along with the growing demand for energy and the environment problem, speed up the construction of the new energy becomes one of the important objectives of the development of national economic construction. As the world’s largest developing country, china’s energy production and consumption is huge. Due to the continued growth of the energy supply, it provides important support for china’s economic development. With the gradual improvement of the requirement to the environment, it is facing a big test for the power system which is mainly composed of thermal power. So, to develop new energy power systems as photovoltaic and wind power is a big trend.The distributed generation and microgrid research has become one of the core subject since Europe and the united states first put forward the development of microgrid. The diversification of energy supply and environmentally friendly features make the microgrid a ideal power supply way.To achieve the proper power balance and improve the system stability, this paper proposed a new drop control method for interlinking converters in hybrid microgrid. In this paper, the main work is in the following respects.(1) A hybrid microgird topology which formed by tying a dc and an ac sub-grid together through interfacing converter were used in this paper. The hybrid microgrid has both ac and dc microgrid advantages, it supports plug and play and can also adjust the power balance automatically, the control methods solely base on local measurements exhibit a superior redundancy, as they do not rely on communication for reliable operation. Due to the use of the hybrid microgird topology, the system capacity of microgird has been expanded. Meanwhile, the new energy utilization and the reliability of the system has also been improved.(2) For the hybrid microgrid set up in this paper, its running mechanism has been analyzed in detail, and the interlinking converter operating control goal has also been designed based on microgrid power management. Hybrid microgrid connect to the power grid through the PCC point under grid-connected mode. Energy can be exchanged between the two system when necessary to ensure the stable operation of the system. It can also be run in a separate ac and dc microgrid under islanded mode, and energy can be exchanged through interlinking converter to ensure the internal important load of the hybrid microgrid operating normally.(3) A new control method has been proposed based on the power balance state and operating mode of the ac microgrid and the dc microgrid. The new control method can change the interlinking converter operating mode through adjusting the PWM waveform which is used to control the interlinking converter by detecting the frequency instantaneous value of the ac microgrid and the dc bus voltage instantaneous value of the ac microgrid.(4) For verifying its performance, MATLAB/Simulink simulation and experiment was executed with the proposed droop control scheme applied to the hybrid microgrid.(5) To inhibit the large number of harmonics caused by the power electronic device, the output filter device has also been designed to improve the power quality of the system and ensure stable operation of the microgrid.The new droop control scheme has been proposed for maintaining the power balance of the hybrid microgrid and ensuring the stablity of the system. To avoid the unnecessary swith action of the power electronic device, the idle mode was added in the droop control scheme. The simulation and experiments show that the misoperation of the interlinking converter is avoided and the working life of the device is prolonged. Meanwhile, the operation maintenance cost of the device would also be reduced. |
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