Microgrid layered and synchronous control method

Abstract

The invention discloses a microgrid layered and synchronous control method. The microgrid adopts the double-perturbation synchronous control strategy based on the Fourier transformation to perform synchronous grid connection. In the case of island or grid-connection model of the microgrid, microgrid PCC (point of common coupling) frequency and voltage amplitude is detected by SFR-PLL (synchronous reference frame-phase-locked loop), and by the use of a PI (proportional plus integral) controller of a recovery control loop, zero-error tracking of the microgrid PCC frequency and voltage amplitude to a target frequency and voltage amplitude is achieved. As the microgrid transforms from the island model to the grid-connection model, frequency correction is added in the second-layer control of the microgrid, phase and voltage amplitude are subjected to perturbation control, voltage differences of two sides of a grid-connection switch are performed with the Fourier transformation, the perturbation and observation method is employed to allow the two-side voltage phases and amplitudes synchronous, current shock of a close grid-connection switch to the microgrid is restrained, seamless switching is realized during model transformation, smoothness is improved during the transition process, and guidance is provided for large-scale renewable energy system connection.

Description

technical field [0001] The invention relates to the field of renewable energy power generation microgrids, in particular to a layered synchronization control method suitable for microgrids. Background technique [0002] In recent years, the rapid development of renewable energy represented by solar energy and wind energy has led to the large-scale grid connection of distributed systems based on power electronic devices, and the reliable, stable operation and high-quality power output of the grid-connected system are the key to the security of the grid. Strong guarantee for operation. The microgrid is a centralized management of distributed systems in the region, which can operate in grid-connected or island mode, reduce the adverse impact of intermittent distributed systems on the distribution network, maximize the use of renewable energy, and improve the reliability of power supply and power quality. Connecting the distributed system into the distribution network in the f...

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Problems solved by technology

[0005] Based on the above problems, the present invention proposes a hierarchical synchronous control method suitable for microgrids. Aiming at the problem of synchronizing with the power grid during the working mode conversion process, a dual-disturbance synchronous control based on Fourier transform is proposed. This strategy adds frequency correction, phase and voltage amplitude disturbance control to the second-layer control of the microgrid, performs Fourier transform on the voltage difference on both sides of the grid-connected switch, and adopts the disturbance observation method to make the voltage on both sides basically The wave components are synchronized, suppressing the current impact on the microgrid caused by closing the grid-connected switch

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