Three-phase unbalanced intelligent compensation device

Abstract

A three-phase unbalanced intelligent compensation device comprises a signal sampling unit, a central control unit, a positive sequence and negative sequence compensation unit and a zero sequence compensation unit and is characterized in that the signal sampling unit is connected in series with a voltage sampling unit and a current sampling unit on a power grid, the signal sampling unit is used for sending information sampled by the voltage sampling unit and the current sampling unit to the central control unit for processing and analysis, the central control unit controls the positive sequence and negative sequence compensation unit and the zero sequence compensation unit which are connected to the power grid, the positive sequence and negative sequence compensation unit comprises an LCL filter and a positive-negative sequence IGBT (Insulated Gate Bipolar Transistor) inversion bridge, and the zero sequence compensation unit comprises a zigzag transformer and a zero sequence IGBT inversion bridge. By the three-phase unbalanced intelligent compensation device, electric energy loss and device loss caused by three-phase unbalance can be effectively improved, a zero sequence current and a negative sequence current existing in the power grid are effectively compensated, a positive sequence current is transferred among phases, so that the three-phase current is balanced. The three-phase unbalanced intelligent compensation device has the advantages of fast response speed and high tracking accuracy, stepless regulation is achieved, and the stability and the reliability of the power grid can be greatly improved.

Description

technical field [0001] The invention belongs to the technical field of electric low-voltage distribution network, and in particular relates to a three-phase unbalance intelligent compensation device used for three-phase unbalance control of low-voltage distribution network. Background technique [0002] In my country's low-voltage distribution network, three-phase four-wire wiring is used. Due to various reasons such as low-voltage single-phase loads cannot be fully divided manually, and the actual operating rate of the distributed loads is different, it is inevitable to cause unbalanced three-phase loads. of. And this unbalanced three-phase load will inevitably lead to increased loss, decreased power efficiency, increased zero-sequence current, and shortened service life of equipment. [0003] Harm to the transformer: The unbalanced three-phase load will make the transformer run asymmetrically, which will increase the loss of the transformer. According to the transformer o...

AI Technical Summary

Problems solved by technology

In addition, the unbalanced three-phase load will cause excessive zero-sequence current of the transformer, increase the temperature of some metal parts, and even cause the transformer to burn out

[0004] Neutral line and neutral point voltage problems: The zero-sequence current of the neutral line is too large, causing the neutral line to burn out, causing problems such as excessive neutral point voltage offset

[0010] At present, there are also phase-separated reactive power compensation devices to compensate the load, which can only compensate for the reactive current part in the system, but can't do anything for the asymmetrical active current part. Sometimes the reactive power compensation makes the current unbalanced It may be larger, so the power supply department of the electric industry can only use manual branching to adjust the load

[0011] The three-phase unbalance of the power system has very serious harm and influence on transformers, electrical equipment and power systems, especially it constitutes a great obstacle to the full and effective use of electric energy.

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