H-bridge cascaded multilevel voltage sag generator based on insulated gate bipolar transistor (IGBT)

Abstract

The invention relates to an H-bridge cascaded multilevel voltage sag generator based on an insulated gate bipolar transistor (IGBT). The generator is characterized in that the generator is an energy feedback four-quadrant converter and can realize bidirectional energy flow; an input end of the generator is connected with a power grid, and an output end of the generator is connected with a system under test (SUT); the energy feedback four-quadrant converter is formed by connecting one phase with three-phase Y, wherein the one phase is formed by overlaying a plurality of low-voltage H-bridge frequency conversion power units in series, and the energy feedback four-quadrant converter is connected with a wind power generation system or photovoltaic system under test; rectification sides of theH-bridge frequency conversion power units are triphase controlled full bridges of IGBT controlled devices, and the triphase controlled full bridges are used for charging filter capacitors after beingrectified; and output sides of the H-bridge frequency conversion power units are composed of four contravariant IGBT controlled devices. The generator provided by the invention not only outputs the voltage sag waveform of the power grid specified in Technical Rule for Connecting Wind Farm to Power Networks, but also freely sets other sag depths and times. The generator is low in self loss, and can carry out research and analysis on trends and reactive power.

Description

Technical field [0001] The invention relates to an IGBT-based H-bridge power unit in series with a multi-level voltage sag generator (VSG) in the power electronics industry. Background technique [0002] Normally, when the power grid fails and the voltage fluctuates greatly, the wind power generation system will automatically disconnect from the grid. As the installed capacity of wind power increases, the impact of this method of dealing with voltage fluctuations on the power grid cannot be ignored. At present, some countries where wind power is dominant, such as Denmark, Germany and other countries have successively formulated new grid operation guidelines, requiring wind power systems to have low voltage ride-through capability LVRT (Low Voltage Ride-Through), only when the grid voltage drops to a certain level. The wind turbine is allowed to go offline only after the degree. my country’s "Technical Regulations for Wind Farm Access to Power System" promulgated in 2009 stipulat...

AI Technical Summary

Problems solved by technology

The existing (VSG) at home and abroad mainly has the impedance form and the transformer form, but the voltage sag depth and frequency fluctuations generated by these two forms of voltage sag generators (VSG) cannot be flexibly controlled, and the energy loss is large, so it is not easy to carry out power flow and Reactive Research Analysis

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