Unbalanced-load-inhibiting SVG and control method

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...

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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 The current detection method and PWM modulation technology can only be applied in the three-phase three-wire system. However, most of the practical applications are three-phase four-wire systems. The existence of a large number of three-phase four-wire systems and unbalanced systems makes the neutral line The current also causes great harm. In this case, the traditional three-phase three-leg SVG cannot be used, and a new three-phase four-leg SVG must be used.

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