Asymmetric fault ride-through system and method for three-phase four-wire system virtual synchronous generator

Abstract

The invention discloses an asymmetric fault ride-through system and method for a three-phase four-wire system virtual synchronous generator, and the method comprises the steps: obtaining the voltage of a common coupling point of a power grid through an acquisition module when an asymmetric fault happens to the power grid, and enabling a fault type detection module to detect whether a correspondingphase breaks down or not according to the voltage of the common coupling point; and meanwhile, the internal potential selection module calculates a virtual impedance value according to the fault type, so that the virtual impedance module adds virtual impedance to the fault phase according to the virtual impedance value to limit the current of the fault phase, and the virtual impedance is removeduntil the fault phase returns to normal. And if the phase has no fault, an inertia link and a damping link are added through the virtual synchronous control module, so that the phase is kept stable. The technical problems that an existing three-phase three-wire system VSG technology has high requirements for a controller in engineering practice and is difficult to achieve in a high-power system are solved.

Description

technical field [0001] The present application relates to the field of electric power technology, in particular to an asymmetrical fault ride-through system and method for a three-phase four-wire virtual synchronous generator. Background technique [0002] In the current research, distributed clean energy is mostly connected to the large power grid in the form of a microgrid. The electrical system can realize internal self-management and control. There are two main operating modes of the microgrid: the grid-connected mode integrated into the large grid and the island mode separated from the large grid. The grid-connected mode needs to be connected to the grid through a grid-connected inverter; , the control methods of grid-connected inverters can be divided into current-type control and voltage-type control. However, these two control methods are easily affected by grid fluctuations such as load fluctuations or short-circuit faults due to their fast response speed and small...

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Problems solved by technology

[0005] The embodiment of the present application provides an asymmetrical fault ride-through system and method for a three-phase four-wire virtual synchronous generator, which is used to solve the problem that the existing three-phase three-wire VSG technology has high requirements on the controller in engineering practice, and in large Difficult technical issues in power systems

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