Voltage control and phase shift compensation method for three-phase grid connection current transformer under power grid failure conditions

Abstract

The invention relates to a voltage control and phase shift compensation method for a three-phase grid connection current transformer under power grid failure conditions. The method includes the following steps that collected three-phase power grid voltages undergo Clarke transformation, and U<alphad> and U<betad> are obtained as feedforward quantities of a first set of power grid voltages for direct feedforward; Park transformation trapped wave separation is performed on the U<alphad> and the U<betad> to obtain the positive-sequence components and the negative-sequence components of the power grid voltages, the inherent delay angle theta<delay> is calculated according to low-pass filtering, AD sampling and a DSP, the components of the phase shift compensation quantities of the positive sequence and the negative sequence of the power grid voltages in a power grid positive and negative DQ coordinate system are respectively calculated, iPark transformation is performed on the positive and negative sequence phase shift compensation quantities through the angles + / -(omega*t+theta<delay>) which are compensated for, and the feedforward compensation quantities of a second set of power grid voltalges are obtained. The voltage control and phase shift compensation method for the three-phase grid connection current transformer under power grid failure conditions has the advantages that under power grid failure conditions, the feedforward control quantities of the power grid voltages can be responded to fast and accurately, and thus stable and reliable operation of the three-phase grid connection current transformer can be guaranteed, and high-voltage and low-voltage failure ride-through of a power grid is achieved.

Description

technical field [0001] The invention relates to a method for voltage control and phase shift compensation of a three-phase grid-connected converter under grid failure. Background technique [0002] With the development of the new energy industry for many years, the standards and requirements for the converters interfaced with the power grid are gradually becoming more and more perfect. In recent years, the converters must be able to successfully ride through faults and maintain normal operation under various fault conditions in the power grid. Power grid faults can be generally divided into three-phase symmetrical faults and three-phase asymmetrical faults, and three-phase asymmetrical faults have more stringent requirements on converters. [0003] At present, for the situation of three-phase asymmetrical faults in the power grid, the feedforward decoupling control of the double synchronous positive and negative sequence DQ rotating coordinate system with a completely symmet...

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Problems solved by technology

[0005] In order to solve the hysteresis delay in the feed-forward decoupling control of the positive and negative sequence separation of the grid voltage under the existing double synchronous rotating coordinate system, in the case of a grid voltage fault, the voltage feed-forward amount cannot effectively respond quickly and the grid-connected current will appear Overcurrent phenomenon, the purpose of the present invention is to provide a three-phase grid-connected converter under grid faults that ensures the response speed under grid faults, reduces the adjustment amount of the current loop quickly enough, and ensures the stable and reliable operation of the three-phase grid-connected converter. Voltage control and phase shift compensation method to realize high and low voltage fault ride-through of power grid

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