Phase self-tracking grid-connected pre-synchronization control method without phase-locked loop

Abstract

The invention discloses a phase self-tracking grid-connected pre-synchronization control method without a phase-locked loop. The method comprises the steps that 1) the electrical angle theta of a modulated wave is acquired through an active power loop in a virtual synchronous generator or droop control; 2) the electrical angle of the modulated wave is compensated; 3) the phase and amplitude of theoutput voltage of a grid-connected inverter are adjusted to make the phase and amplitude the same as the phase and amplitude of the voltage of a grid; 4) a three-phase grid-connected contactor is closed; and 5) phase and amplitude pre-synchronization control is disconnected to adjust the grid-connected inverter. According to the method provided by the invention, phase self-tracking grid-connectedpre-synchronization control without the phase-locked loop is used; theta used by a dq-axis rotating coordinate system is used as the output phase angle theta of the active power loop of the virtual synchronous generator or droop control; phase locking of the voltage of the grid is eliminated; and an algorithm is simplified.

Description

technical field [0001] The invention belongs to the technical field of grid-connected pre-synchronization control, and relates to a phase self-tracking grid-connected pre-synchronization control method without a phase-locked loop. Background technique [0002] In recent years, energy and environmental issues have become a huge challenge for the development of human society. New energy sources have been widely used, and more and more distributed power sources have begun to be connected to the grid. These new energies are connected to the grid through grid-connected inverters, which can stably transmit power to the grid when the grid voltage is normal. In the event of a grid failure or power outage, the inverter is disconnected from the grid, continues to supply uninterrupted power to nearby critical loads in an independent operation mode, and can be connected to the grid again when the grid is restored. Therefore, grid-connected smooth switching technology has always been a ...

AI Technical Summary

Problems solved by technology

[0007] The purpose of the present invention is to provide a phase-locked-loop self-tracking grid-connected pre-synchronization control method, which solves the problem that the inverter output voltage and grid voltage phase Inconsistency, the traditional control algorithm is relatively cumbersome, which increases the problem of system instability

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