A Control Method for Parallel Power Balance of Modular Uninterruptible Power Supply

Abstract

The invention discloses a control method for parallel power balance of modular uninterruptible power supplies, which specifically includes the following steps: establishing an equivalent control model for parallel connection of inverter parts of two single-phase uninterruptible power supplies, and the inverter adopts a half-bridge structure; The current and average power of two parallel UPSs adopts the virtual resistance feedback control strategy, through the series virtual resistance equivalent to realize the suppression of parallel circulating current, and enhance the current and average power capacity of the system, including: the suppression of active circulating current, reactive circulating current and DC circulating current. The present invention aims at two single-phase UPS inverter part parallel connection load power supply system, adopts the control method of equivalent series virtual resistance, by adding virtual resistance feed-forward loop in the UPS inverter voltage and current loop control block diagram, greatly reduces the The circulating currents caused by differences in each parallel UPS can suppress the active circulating current and reactive circulating current, and then balance the output power of the parallel system; realize the suppression of the overall circulating current, and improve the current sharing capability of the parallel system.

Description

technical field [0001] The patent of the present invention relates to a control method for parallel power balance of modularized uninterruptible power supplies. Background technique [0002] With the continuous development of modern industry, electrical equipment is becoming more and more abundant, and a large number of precision instruments and equipment appear in modern industrial occasions, playing an irreplaceable role in the fields of transportation, information communication, and industrial automation production. Whether these equipment can operate safely, reliably and continuously is directly related to people's production and life. Whether the equipment can operate reliably and stably depends not only on the technology and quality level of the equipment itself, but also on whether it can provide stable security. Reliable power. [0003] With the continuous development of power electronics technology, power conversion technology makes AC-DC and DC-AC conversion possi...

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Problems solved by technology

[0005] Although parallel UPS can improve the stability of the power supply system, due to the differences in the characteristics of each UPS device and the length of the connection line to the load, there are differences in the output internal impedance of different units in the parallel system, even if the amplitude, phase and frequency of the output voltage of each UPS Exactly the same, this difference will also cause uneven distribution of power and output current to the load, resulting in circulating current between parallel UPSs, affecting the output characteristics of UPS

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