The bidirectional converter in AC / DC hybrid microgrid is an important link to balance the power on both sides of AC and DC, Its control method is extremely important. This paper proposes an improved droop control strategy for bidirectional converter using DC-side power amount control. This control can autonomously and smoothly switch in rectifyer, inverter and idle modes. Utilizing DC-side power control avoids normalized calculations. Strategy meets two modes of island and grid connection, eliminating the need for multiple control strategy switches. Simulation results show that the DC bus voltage and AC frequency are near the rated value, which guarantees the stable operation of the AC-DC hybrid microgrid.
Based on the improved droop control of the bidirectional converter controlled by the DC (direct current) side power quantity, a coordinated control scheme with energy storage is proposed. Not only can the two-way converter automatically and smoothly switch in the rectification, inverter, and idle modes, but also the energy storage device can perform coordinated control in the DC side idle mode to maintain the DC bus voltage stability. Using DC side power control, there is no need to switch control strategies to meet islanding and grid-connected modes. The simulation results show that improved droop control can reduce frequent actions of power electronic devices caused by small-range fluctuations in DC bus voltage and AC (alternating current) frequency. Coordinated control can make the DC bus voltage more stable, ensure stable operation of the AC and DC hybrid microgrid, and improve system reliability.
With the continuous development of social economy, the demand for electricity is increasing day by day. Power users have higher and higher requirements on the reliability of power supply. In case of grid failure, The impact on businesses and individuals is also growing. The reliability of medium voltage power supply system has been paid more and more attention. The reliability of medium voltage power supply has a direct impact on users’ satisfaction with electricity consumption. Power supply reliability has become an important index to reflect the continuous power supply capacity of enterprises. Power supply enterprises pay more attention to power supply reliability year by year. Improving the reliability of power supply for medium voltage users has become an important part of reliability management. The author summarizes the work experience, the main factors affecting the reliability of medium voltage supply are analyzed. The measures and methods to improve the reliability of medium voltage power supply are put forward.
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