Unbalanced-load-inhibiting SVG and control method

A static reactive power and load balancing technology, applied in reactive power adjustment/elimination/compensation, flexible AC transmission system, AC network to reduce harmonics/ripples, etc., can solve hidden dangers of reactive power and harmonic grid safety , electrical design qualification rate decline, zero line current hazards and other issues

Inactive Publication Date: 2013-12-25
HARBIN UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] With the gradual increase of high-power nonlinear loads in the three-phase four-wire system, a large amount of zero-sequence current has accumulated on the neutral line, which seriously reduces the qualification rate of electrical design, and a large amount of reactive power and harmonics have also caused damage to the power grid. Significant safety hazard, the traditional three-phase three-arm main circuit topology of the SVG adopts i p , i q Th

Method used

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  • Unbalanced-load-inhibiting SVG and control method
  • Unbalanced-load-inhibiting SVG and control method
  • Unbalanced-load-inhibiting SVG and control method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0076] A static var generator SVG for suppressing unbalanced loads, comprising: a three-phase four-leg inverter, the three-phase four-leg inverter is connected to a three-phase AC power supply, and the three-phase The four-bridge arm inverter is connected to the isolation drive circuit, the isolation drive circuit is connected to the DSP2812 chip, the DSP2812 chip is connected to the voltage Hall module, the DSP2812 chip is connected to the current Hall module, and the The current Hall module is connected to the three-phase AC power supply, the three-phase AC power supply is connected to the load, and the three-phase AC power supply is connected to the voltage zero-crossing detection module.

Embodiment 2

[0078] According to the static var generator SVG for suppressing unbalanced loads described in Embodiment 1, the a-phase line of the three-phase AC power supply is connected to the bridge arm A of the three-phase four-leg inverter through an inductance, The b-phase line of the three-phase AC power supply is connected to the bridge arm B of the three-phase four-leg inverter through an inductance, and the c-phase line of the three-phase AC power supply is connected to the three-phase four-bridge inverter The bridge arm C of the arm inverter is connected through an inductance, the neutral line of the three-phase AC power supply is connected to the bridge arm D of the three-phase four-arm inverter, and the a-phase line is connected to the voltage The zero-crossing detection module is connected, and the current Hall module is respectively connected with the a-phase line, the b-phase line, and the c-phase line.

Embodiment 3

[0080] The above-mentioned control method of the static var generator SVG suppressing the unbalanced load,

[0081] (1) Control method of the control unit:

[0082] In the α-β coordinate system, the instantaneous value of each phase voltage in the three-phase system is set as e a 、e b 、e c , the instantaneous value of the three-phase current is i a 、i b 、i c ; First, transform the three variables in the three-dimensional space coordinate system into two two-dimensional variables in the α-β coordinate system, and the instantaneous voltage in the two-dimensional coordinate systeme α 、e β and instantaneous current i α 、i β It can be obtained by the following formula;

[0083] (1)

[0084] (2)

[0085] in:

[0086] (3)

[0087] The rotation vectors e and i are respectively composed of vectors on the α-β plane 、 and 、 synthesis:

[0088] (4)

[0089] ...

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Abstract

Disclosed are an unbalanced-load-inhibiting SVG (Static Var Generator) and a control method. Traditional SVGs with three-phase three-bridge-arm main circuit topology structures are only applicable to a three-phase three-wire system. However, in practical application, three-phase four-wire systems and unbalanced systems exist in large quantity, wherein zero-line current also causes comparatively great harms. The unbalanced-load-inhibiting SVG includes a three-phase four-bridge-arm inverter (2) which is connected with a three-phase AC power supply (1) and an isolation driving circuit (3). The isolation driving circuit is connected with a DSP2812 chip (4). The DSP2812 chip is connected with a voltage Hall module (5) and a current Hall module (6). The current Hall module is connected with the three-phase AC power supply. The three-phase AC power supply is connected with a load (7) and a voltage zero-cross detection module (8). The unbalanced-load-inhibiting SVG and the control method are used for electric-energy quality improvement of power grids.

Description

Technical field: [0001] The invention relates to a static var generator SVG for suppressing unbalanced loads and a control method. Background technique: [0002] In recent years, power electronics technology has developed rapidly, especially in the field of electric power on a large scale. As unbalanced and non-linear loads continue to increase in the low-voltage distribution network, the power quality is seriously affected. Since there is no neutral current in the three-phase three-wire system, the reactive power compensation strategy under this system is only Negative sequence current compensation needs to be considered. [0003] With the gradual increase of high-power nonlinear loads in the three-phase four-wire system, a large amount of zero-sequence current has accumulated on the neutral line, which seriously reduces the qualification rate of electrical design, and a large amount of reactive power and harmonics have also caused damage to the power grid. Significant sa...

Claims

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Application Information

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IPC IPC(8): H02J3/18H02J3/01
CPCY02E40/10Y02E40/40
Inventor 高晗璎刘端增李伟力邵春伟孟春成周永勤朱建良王中明
Owner HARBIN UNIV OF SCI & TECH
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