WO2016195122A1 - Application de circuit de rectification virtuel dans des systèmes d'alimentation électrique - Google Patents

Application de circuit de rectification virtuel dans des systèmes d'alimentation électrique Download PDF

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Publication number
WO2016195122A1
WO2016195122A1 PCT/KP2016/000043 KP2016000043W WO2016195122A1 WO 2016195122 A1 WO2016195122 A1 WO 2016195122A1 KP 2016000043 W KP2016000043 W KP 2016000043W WO 2016195122 A1 WO2016195122 A1 WO 2016195122A1
Authority
WO
WIPO (PCT)
Prior art keywords
direct current
power
rectification circuit
earth
alternating current
Prior art date
Application number
PCT/KP2016/000043
Other languages
English (en)
Inventor
Yong Se Kim
Original Assignee
Jong Yong Hwa
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Jong Yong Hwa filed Critical Jong Yong Hwa
Publication of WO2016195122A1 publication Critical patent/WO2016195122A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0007—Frequency selective voltage or current level measuring
    • G01R19/0015—Frequency selective voltage or current level measuring separating AC and DC

Definitions

  • the invention relates to the sensing of direct current that is unintentionally embedded in the standard alternating current power systems and its application.
  • the object of the present invention is to provide method for detecting direct current occurred around specific points along electrical lines of a power system.
  • Figure 1 shows an oscillogram of the asymmetric current wave appearing when a power line of an alternating current power system is down to earth giving rise to an arc discharge.
  • Figure 2 shows an approximation of the wave-form of Fig. 1.
  • Figure 3 shows an equivalent circuit of the point at which the asymmetric wave of Fig. 1 is formed.
  • Figure 4 shows an exemplary system for detecting direct current components formed by the circuit of Fig. 3.
  • the wave-form of alternating current flowing among power systems should be symmetric in general. However, there are cases where the wave-form of alternating current may become asymmetric. If, for example, an overhead electric wire of a power system is accidentally down to the earth or to a tree giving rise to a spark discharge or arc discharge, the maximum discharge value at the positive half-cycle is not in exact agreement with that at the negative half-cycle as can be seen in Fig. 1. The symmetry of the alternating current discharge wave-form is believed to break due to the asymmetry of physical characteristics among the electric wire and the earth or the trees.
  • thermoelectron emission should result in the asymmetry of the thermoelectron emissions at the wire and at the earth or the trees which should intensify the asymmetry of the wave-form of the discharge electricity.
  • appeal to the thermoelectron emission seems reasonable in view of the very high heat produced during spark or arc discharging.
  • Fig. 1 Considering only maximum half-cycle values of the discharge current in Fig. 1 gives rise to the wave-form as shown in Fig. 2 which may be expanded into Fourier series as in Formula (1) below.
  • the sum of the first two terms corresponds to Fourier series of half-wave rectification of a symmetrical isosceles triangular wave current with maximum value of AI m!a and the third term becomes Fourier series of a symmetrical isosceles triangular wave current with maximum value of 7 maxn .
  • a rectification circuit may be imagined as an equivalent circuit of the asymmetry-generating point. This is what the virtual rectification circuit is of the present invention.
  • the occurrence of direct current in the alternating current power may be interpreted as accident in case of a power transmission-distribution system or as decrease of powr factor in case of an
  • Fig. 3 shows virtual construction of the rectification circuit that is formed at an accidental earthing point along a power substation line.
  • the rectification circuit is constructed to comprise nonlinear effective resistance in view of the non-linearity of spark or arc resistance.
  • Virtual construction of the rectification circuit at the accidental earthing point makes it possible to detect the accidental earthing by sensing direct current components that are embeded in the alternating current power.
  • Direct current components produced by the virtual rectification circuit comprise direct voltage, direct current, and internal resistance of the rectification circuit.
  • Direct current components formed at the virtual rectification circuit are independent of the value of the electrostatic capacity of the power wire vis-a-vis the earth and of the voltage disbalance at the power system.
  • the sensitivity of detection of direct current components is proportional to the degree of asymmetry of the alternating discharge current, namely the magnitude of the difference of the maximum discharge values at the positive half- cycle and at the negative half-cycle.
  • the sensitivity will be inversely proportional to the value of the transition resistance at the asymmetry-generating point.
  • System for detecting direct current components may comprise means for separating direct current components from the main alternating current power (1) and means for indicating the occurence of direct current components (2).
  • Fig. 4 shows one of the embodiments of detecting direct current components generated by the virtual rectification circuit of Fig. 3.
  • means for separating direct current components comprise a single-phase voltage transformer (1) connected to any of power lines of the substation and an earth capacitor (2) connected at one end to the primary winding of the voltage transformer and to the earth at another end and having electrostatic capacity large enough to short zero-phase sequence voltage and disbalanced alternating voltage of the power end. Since direct current components that may originate at any one of three phase lines of the power system should appear simultaneously at the three phases, it is possible to detect accidental earthing using only one single-phase voltage transformer connected to any one power line as in Fig 4. And furthermore, since the direct current resistance of the primary winding of the single-phase voltage transformer is very small relative to its alternating current resistance, there will be no problem in using a single-phase voltage transformer.
  • means for indicating the occurence of direct current components comprise one or both of a direct current amperemeter and a light or sound alarm generator connected to the above-mentioned earth capacitor.
  • the system comprises a rectifier between the said earth capacitor and the said indicating means as in Fig. 4.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

La présente invention concerne l'application de circuit de rectification virtuel. L'invention concerne plus particulièrement un système de détection de courant continu qui peut se produire à un point le long d'une ligne électrique d'un système d'alimentation en courant alternatif, comprenant des moyens pour séparer des composantes de courant continu à partir d'une alimentation en courant alternatif et des moyens pour indiquer l'apparition de composantes de courant continu.
PCT/KP2016/000043 2015-06-05 2016-06-02 Application de circuit de rectification virtuel dans des systèmes d'alimentation électrique WO2016195122A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KP201510001909 2015-06-05
KP190915 2015-06-05

Publications (1)

Publication Number Publication Date
WO2016195122A1 true WO2016195122A1 (fr) 2016-12-08

Family

ID=57442380

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/KP2016/000043 WO2016195122A1 (fr) 2015-06-05 2016-06-02 Application de circuit de rectification virtuel dans des systèmes d'alimentation électrique

Country Status (1)

Country Link
WO (1) WO2016195122A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2231673B (en) * 1989-04-18 1993-01-27 Standard Telephones Cables Ltd Direct current meter circuit
US5648723A (en) * 1994-05-09 1997-07-15 Adb-Alnaco, Inc. Method and apparatus for separating and analyzing composite AC/DC waveforms
DE202007019127U1 (de) * 2007-03-19 2010-11-04 Balfour Beatty Plc Vorrichtung zur Messung eines von einem Wechselstromanteil überlagerten Gleichstromanteils eines in Leitern von Wechselstrombahnen fließenden Stroms
CN102435810A (zh) * 2011-09-14 2012-05-02 北京国基科技股份有限公司 一种交流电中检测直流分量的方法及装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2231673B (en) * 1989-04-18 1993-01-27 Standard Telephones Cables Ltd Direct current meter circuit
US5648723A (en) * 1994-05-09 1997-07-15 Adb-Alnaco, Inc. Method and apparatus for separating and analyzing composite AC/DC waveforms
DE202007019127U1 (de) * 2007-03-19 2010-11-04 Balfour Beatty Plc Vorrichtung zur Messung eines von einem Wechselstromanteil überlagerten Gleichstromanteils eines in Leitern von Wechselstrombahnen fließenden Stroms
CN102435810A (zh) * 2011-09-14 2012-05-02 北京国基科技股份有限公司 一种交流电中检测直流分量的方法及装置

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