Two-point active control method for asymmetrical voltage in non-effectively grounded neutral system

A technology of non-effective grounding and control method, applied in the direction of reducing the asymmetry of the polyphase network, eliminating/reducing the asymmetry of the polyphase network, etc., it can solve the problems of long control time, etc., and achieves large construction volume, high difficulty and self-adaptation Effects of Changes in Line Parameter Structure

Inactive Publication Date: 2016-04-20
CHINA UNIV OF PETROLEUM (EAST CHINA)
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AI Technical Summary

Problems solved by technology

The current active control method for asymmetric voltage is mainly the tracking control method, which changes the phase and amplitude of the injected current sequentially according to the change rule of the asymmetric voltage with the injected current, and controls the asymmetric voltage to approach the target value. The method needs to gradually adjust the injection current. When the initial injection current and step size are unreasonable, the control time will be longer

Method used

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  • Two-point active control method for asymmetrical voltage in non-effectively grounded neutral system
  • Two-point active control method for asymmetrical voltage in non-effectively grounded neutral system
  • Two-point active control method for asymmetrical voltage in non-effectively grounded neutral system

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Embodiment Construction

[0021] The specific implementation of the method of the present invention is:

[0022] (1) Active compensation device

[0023] Active compensation device based on active power electronic devices and pulse width modulation technology (pulsewidthmodulation, PWM) (as attached image 3 (Shown) is mainly composed of control, input, rectification, inverter, output and other auxiliary units. The control unit controls the rectification and inverter units according to the measurement data and algorithms, and converts the three-phase AC input voltage into a suitable PWM voltage wave. The required injection current is output through the output unit. Its capacity is generally 1MVA (in 10kV distribution network) or 2MVA (in 35kV distribution network) to meet the requirements, and the capacity can be further reduced when combined with a fixed compensation arc suppression coil. The active compensation device can inject any amplitude and phase current into the system to realize the control of as...

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Abstract

The invention discloses an asymmetric voltage two-point active control method for a neutral point non-effective grounding system. Asymmetric voltages caused by circuit three-phase parameter imbalance can be controlled to any given target value. According to the method, injection currents for controlling the asymmetric voltages into any target value are calculated according to the calculation of the two different injection currents and the asymmetric voltages corresponding to the injection currents, three-phase earth admittance and line impedance of a measuring system are not needed in the method, self-adaptation to dynamic changes of line parameters and structures can be achieved, errors caused by line impedance voltage drop and the like can be avoided, the control speed is high, precision is high, the asymmetric voltages of the neutral point non-effective grounding system can be flexibly controlled to maintain grid three-phase voltage balance, and the safe and economical operation of a grid is ensured.

Description

Technical field [0001] The invention belongs to the field of power system three-phase voltage unbalance control, and relates to an asymmetric voltage control method for a neutral point non-effective grounding system. [0002] The invention particularly relates to a control method for controlling the asymmetric voltage of a neutral point ineffective grounding system to an arbitrary target value by using an active compensation technology. Background technique [0003] As the development direction of the future distribution network, the intelligent distribution network puts forward higher requirements for power quality and safety performance. Asymmetric voltage control will be one of the important contents. In the medium voltage distribution network, factors such as poor transposition of overhead lines, unequal three-phase parameters (including length) of single-core cable lines, non-full-phase power supply, and three-phase unbalanced installation of coupling capacitors for carrier co...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/26
CPCY02E40/50
Inventor 薛永端谢菁
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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