Pscad modeling and simulation method of grid-connected converter in case of grid asymmetry fault

Abstract

The invention relates to a PSCAD modeling and simulation method for a grid-connected inverter during an unsymmetrical failure of a power grid and belongs to the technical field of PSCAD modeling and simulation methods. The technical problem to be solved is providing a PSCAD modeling and simulation method for a grid-connected inverter under a positive-negative dual-sequence independent control strategy. The technical scheme comprises following steps: first, the positive-negative sequence voltage and current of the three-phase voltage and current of the AC side of the grid-connected inverter are separated; the three-phase positive and negative voltage and current are converted to a [alpha][beta] axis to obtain reference values of positive-negative sequence current of a dq axis; then the PI parameter of current inner loop and voltage outer loop is calculated. The method is suitable for electrical power systems.

Description

technical field [0001] The invention discloses a PSCAD modeling and simulation method for a grid-connected converter when an asymmetric fault occurs in a power grid, and belongs to the technical field of PSCAD modeling and simulation methods. Background technique [0002] At present, many components with non-power frequency output frequency must be connected to the grid through PWM converters, such as photovoltaic power generation systems, direct drive fans, etc. When an asymmetric fault occurs in the grid, according to the instantaneous power theory, the grid-connected converter The active and reactive power on the AC side contains second harmonic components. At the same time, the bus voltage on the DC side also has a second ripple. When the ripple is large enough, it will affect the normal operation of the converter or even damage the converter. , in order to limit the ripple of the DC bus voltage of the converter, a double current loop control strategy with positive and n...

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Problems solved by technology

[0002] At present, many components with non-power frequency output frequency must be connected to the grid through PWM converters, such as photovoltaic power generation systems, direct drive fans, etc. When an asymmetric fault occurs in the grid, according to the instantaneous power theory, the grid-connected converter The active and reactive power on the AC side contains second harmonic components. At the same time, the bus voltage on the DC side also has a second ripple. When the ripple is large enough, it will affect the normal operation of the converter or even damage the converter. , in order to limit the ripple of the DC bus voltage of the converter, a double current loop control strategy with positive and negative sequence independent control has been widely used. In order to better analyze the characteristics of the grid-connected converter under this control strategy, it is necessary Research on its modeling method

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