Voltage-type PWM (pulse-width modulation) rectifier output power control method under power grid unsymmetrical fault

Abstract

The invention discloses a voltage-type PWM (pulse-width modulation) rectifier output power control method under a power grid unsymmetrical fault. The technical scheme provided by the invention is characterized in that through the voltage-type PWM rectifier output power control method under the power grid unsymmetrical fault, the output active power and output reactive power which are obtained through calculation are subjected to negation through a band pass filer and a controller; a double frequency offset voltage is obtained through offset voltage calculation, and is offset to the output voltage in traditional vector control; and finally a reference voltage under a two-phase static coordinate system is obtained, a voltage signal generates a switch signal for controlling the power device after being subjected to space vector pulse width modulation, and the output active power and the output reactive power are controlled stably. According to the invention, under the condition of power grid unsymmetrical fault, positive sequence component and negative sequence component in a system are not required to be calculated and resolved; the power pulse of the voltage-type PWM rectifier can be offset directly; the direct-current bus voltage is controlled stably; and the calculation method is simple and can be easily realized.

Description

technical field [0001] The invention relates to a control method of a voltage-type PWM rectifier, which belongs to the control field of power electronic power conversion devices, and in particular relates to a method for controlling the output power of a voltage-type PWM rectifier under an asymmetric fault of a power grid. Background technique [0002] The three-phase voltage PWM rectifier is widely used in rectification, AC speed regulation, active filter, reactive power compensation and new energy grid-connected power generation due to its good input current sine degree, unit power factor, energy bidirectional flow and constant DC voltage. field. In conventional PWM rectifier control strategy research, it is generally assumed that the input voltage of the three-phase power grid is balanced. However, when an asymmetric fault occurs in the power grid, under the traditional double closed-loop control strategy based on vector control, the rectifier DC side will appear second...

AI Technical Summary

Problems solved by technology

This control method requires positive and negative sequence decomposition operations, which will increase the complexity of the controller and reduce the dynamic response speed of the system.

Some scholars use the PR controller to adjust the positive and negative sequence currents uniformly, avoiding the positive and negative sequence decomposition operation process in the current loop, but in order to calculate the positive and negative sequence current given values, this method also needs to Each component is decomposed into positive and negative sequences, which only reduces the calculation amount of the control system to a certain extent.

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