None-serial transformer type dynamic voltage restorer compound control method

Abstract

The invention discloses a none-serial transformer type dynamic voltage restorer compound control method which is a single-phase sine pulse width modulation (SPWM) compound control method based on proportional integration VPI and modified proportional resonance (MPR) double-closed-loop controller parallel running. A single-phase SPWM technology is used in a multi-level inverter of a none-serial transformer type DVR device, and the inverter can obtain high equivalent switch frequency and low switch loss. An inverter control system uses a double-closed-loop control structure of a current inner loop and a voltage outer loop, and the fact that load voltage is maintained at the rated value is guaranteed. The open-loop gain controlled at resonance frequency of the MPR used by the voltage loop is infinite, and complex coordinate transformation, decoupling control and feedforward compensation control in conventional PR control and multiple PI control strategies are avoided.

Description

Technical field [0001] The invention relates to a control method of a series-transformer-free dynamic voltage restorer based on a compound control strategy, which belongs to the field of transient power quality disturbance signal analysis, and is particularly suitable for the detection and compensation control of voltage sag disturbance in the distribution network. Background technique [0002] Since the 1980s, some new power electronic loads have continuously improved power quality requirements, and power quality has become a common concern for power companies and users. Among the many problems of power quality, the harm caused by voltage sag disturbance is the most common. Statistics show that for large power users, the annual rate of voltage sags exceeding 20% ​​is about 10-20 times. Important occasions such as airports, banks, precision electronic component manufacturing, computer networks, and service monitoring centers, etc. The economic losses caused by voltage sags amoun...

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Problems solved by technology

On the other hand, in order to improve the compensation ability of the inverter unit of the DVR device to the harmonic voltage and limit the influence of the nonlinear load on the system voltage to the greatest extent, relevant researchers at home and abroad have done a lot of research on the control strategy adopted by the DVR device. , although it has achieved certain results, it cannot be effectively traded off in terms of system stability, complexity, dynamic response speed, and compensation ability for harmonic voltage.

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