Injection current two-point calculation method during small-current grounding fault active arc extinguishing

A technology of small current grounding and current injection, which is applied to emergency protection circuit devices, electrical components, circuit devices, etc. for limiting overcurrent/overvoltage, and can solve problems such as large current at fault points

Active Publication Date: 2016-02-10
CHINA UNIV OF PETROLEUM (EAST CHINA)
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the existing active arc suppression control methods measure the ground admittance of the system before the fault, and measure the impedance of the neutral point of the system after the fault to calculate the injected current
In the 2 hours allowed to operate with faults after the small current grounding fault occurs, the distribution network line may be switched. At this time, the existing active arc suppression control method is used to calculate and inject the injected current. ground capacitance current, the current at the fault point may still be large

Method used

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  • Injection current two-point calculation method during small-current grounding fault active arc extinguishing
  • Injection current two-point calculation method during small-current grounding fault active arc extinguishing
  • Injection current two-point calculation method during small-current grounding fault active arc extinguishing

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Embodiment Construction

[0027] The specific embodiment of method of the present invention is:

[0028] (1) Structure of active arc suppression system for small current grounding fault (as attached figure 1 shown)

[0029] The measurement signal is sent to the controller, which can be a DSP microprocessor that controls the IGBT and its drive in the active inverter, or a control host. When a small current ground fault occurs, the controller judges the occurrence of a small current ground fault according to the measurement signal, and sends a control signal to the active inverter, and the active inverter outputs a single-phase power frequency AC current according to the control signal.

[0030] After passing through a single-phase step-up transformer, the active inverter can be connected to the neutral point of the system in parallel or in series with the arc suppressing coil, or can be connected in parallel or in series from any one of the three phases. in the attached figure 1 Among them, the activ...

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Abstract

The invention discloses an injection current two-point calculation method employing active inverter to control a fault phase voltage to be zero after a small-current grounding fault. The method can calculate the transitional resistance of a fault point and the injection current, which enables the fault phase voltage to be zero, according a fault phase power voltage, two different injection currents and corresponding bus zero sequence voltages. The method can adapt to the dynamic change of a line structure, is high in precision when the transitional resistance is larger, and solves a problem that a conventional active arc-distinguishing technology (active compensation technology or flexible grounding technology) cannot reflect the dynamic change of the line structure in real time during the calculation of the injection current.

Description

technical field [0001] The invention belongs to the technical field of small current grounding fault self-healing in power systems, relates to the field of arc suppression technology based on active inverters during small current grounding faults, and in particular relates to a method for calculating injected current with active arc suppression technology. Background technique [0002] At this stage, the medium-voltage distribution network in my country widely adopts the low-current grounding method, that is, the neutral point is not grounded and the neutral point is grounded through the arc suppression coil. When a single-phase ground fault occurs, the current at the fault point is small, which is called small current. grounding system. Single-phase ground fault is the main form of distribution network faults, accounting for about 80% of the total faults. When a single-phase ground fault occurs, since the voltage of the three-phase line remains basically unchanged and the c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H9/08
Inventor 薛永端刘维功王森
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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