NO341135B1 - Circuit for supply of short-circuit current - Google Patents

Circuit for supply of short-circuit current Download PDF

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Publication number
NO341135B1
NO341135B1 NO20150289A NO20150289A NO341135B1 NO 341135 B1 NO341135 B1 NO 341135B1 NO 20150289 A NO20150289 A NO 20150289A NO 20150289 A NO20150289 A NO 20150289A NO 341135 B1 NO341135 B1 NO 341135B1
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Norway
Prior art keywords
circuit
short
current
circuit current
supply
Prior art date
Application number
NO20150289A
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Norwegian (no)
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NO20150289A1 (en
Inventor
Bjarte Hoff
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Bjarte Hoff
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Publication date
Application filed by Bjarte Hoff filed Critical Bjarte Hoff
Priority to NO20150289A priority Critical patent/NO341135B1/en
Publication of NO20150289A1 publication Critical patent/NO20150289A1/en
Publication of NO341135B1 publication Critical patent/NO341135B1/en

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Classifications

    • HELECTRICITY
    • H03ELECTRONIC CIRCUITRY
    • H03KPULSE TECHNIQUE
    • H03K17/00Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/08Modifications for protecting switching circuit against overcurrent or overvoltage
    • HELECTRICITY
    • H03ELECTRONIC CIRCUITRY
    • H03KPULSE TECHNIQUE
    • H03K17/00Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/12Modifications for increasing the maximum permissible switched current

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  • Details Of Television Scanning (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
  • Emergency Protection Circuit Devices (AREA)
  • Direct Current Feeding And Distribution (AREA)

Description

BRUKSOMRÅDE AREA OF USE

Oppfinninga angår ein krets som levera kortslutningsstraum til bruk i svake eller isolerte elektriske anlegg, inkludert mikronett, der nettet sjølv ikkje kan levera tilstrekkeleg kortslutningsstraum til å løyse ut installasjonen sine overstraumsvern. Eit aktuelt bruksområde er levering av kortslutningsstraum i kombinasjon med distribuert småskala-produksjon av elektrisitet som solcellepanel, vindturbin eller små vasskraftverk. The invention relates to a circuit that supplies short-circuit current for use in weak or isolated electrical installations, including microgrids, where the grid itself cannot supply sufficient short-circuit current to trip the installation's overcurrent protection. A relevant area of application is the supply of short-circuit current in combination with distributed small-scale production of electricity such as solar panels, wind turbines or small hydropower plants.

BAKGRUNN BACKGROUND

For at overstraumsvernet i ein elektrisk installasjon skal løyse ut ved feil som kortslutning, må det elektriske anlegget kunne levera ein tilstrekkeleg stor kortslutningsstraum. I svake eller isolerte nett er ikkje alltid tilstrekkeleg kortslutningsstraum tilgjengeleg. Dette gjeld spesielt i små isolerte nett med lokal energiproduksjon, slik som solcellepanel, mindre vindturbinar eller små vasskraftverk. Tilhøyrande generatorar eller kraftelektroniske omformarar er ikkje nødvendigvis i stand til å sjølv levera tilstrekkeleg kortslutningsstraum, enten på grunn av utstyret sin dimensjonerte straum, eller energireservar. Slike isolerte nett inkludera også ulike former for mikronett i øydrift. Mikronett er definert som små elektriske kraftnett som inkludera eigen generering av elektrisitet og energilager som kan driftast saman med det resten av kraftnettet, eller som eit isolert nett (øydrift). Mikronett kan vera i form av eit avgrensa geografisk område, eller internt i ein bygning. In order for the overcurrent protection in an electrical installation to trip in the event of a fault such as a short circuit, the electrical installation must be able to deliver a sufficiently large short circuit current. In weak or isolated networks, sufficient short-circuit current is not always available. This applies especially in small isolated networks with local energy production, such as solar panels, smaller wind turbines or small hydropower plants. Associated generators or power electronic converters are not necessarily able to supply sufficient short-circuit current themselves, either because of the equipment's rated current or energy reserves. Such isolated grids also include various forms of microgrids in island operation. Microgrids are defined as small electrical power grids that include own generation of electricity and energy storage that can be operated together with the rest of the power grid, or as an isolated grid (island operation). Microgrids can be in the form of a limited geographical area, or internally in a building.

Ei kjent løysing er å overdimensjonere kraftelektroniske omformar kopla til eit energilager, for eksempel batteri, slik at tilstrekkeleg kortslutningsstraum kan leverast av denne. Det er også foreslått å bruke avanserte vern, med eller utan digital kommunikasjon, for å detektera og kopla ut feil utan å basera seg på kortslutningsstraum. A known solution is to oversize power electronic converters connected to an energy storage, for example a battery, so that sufficient short-circuit current can be supplied by this. It is also proposed to use advanced protections, with or without digital communication, to detect and disconnect faults without relying on short-circuit current.

Å overdimensjonere av kraftelektroniske omformarar fører derimot til eit dyrare anlegg, utan at denne overkapasiteten kan nyttast i normal drift. On the other hand, oversizing power electronic converters leads to a more expensive system, without this excess capacity being used in normal operation.

Avanserte vern fører til eit dyrare og meir komplisert anlegg, samt ein meir arbeidskrevjande prosjektering og igangkjøring av anlegget. Ved ombygging av eksisterande elektriske anlegg til mikronett, er også ynskjeleg å nytta eksisterande vern i installasjonen i størst mogeleg grad. Advanced protection leads to a more expensive and more complicated plant, as well as more labor-intensive planning and commissioning of the plant. When converting existing electrical installations to microgrids, it is also desirable to use existing protection in the installation to the greatest extent possible.

Det er tidlegare i patent «US 80587000 Bl» (Dl) nytta ein kondensator som energilager for å oppretthalde vern mot overstraum i ein integrert transistor-pakke. Oppfinninga skil seg ut ved å levere sjølve kortslutningsstraumen, mens Dl beskriv ein krets for å oppretthalde driftspenning i ein eksisterande vern-krets. Oppfinninga basera seg på å lagra energi ved å lada opp ein kondensator ved å likeretta vekselspenning med ein diode og avgrensa ladestraumen med ein motstand, nokon som er allment kjent kunnskap og blant anna nytta i «US 3959695 A» (D2) og «US 4258403 A» (D3). Det er også i D3 kjent at ein likestraum frå ei kondensator kan nyttast til å løyse ut ein relespole, men verken D2 eller D3 nyttar energi lagra i ein kondensator til å levera kortslutningsstraum direkte i ein elektrisk installasjon. Previously in patent "US 80587000 Bl" (Dl) a capacitor was used as an energy store to maintain protection against overcurrent in an integrated transistor package. The invention stands out by supplying the short-circuit current itself, while D1 describes a circuit for maintaining operating voltage in an existing protection circuit. The invention is based on storing energy by charging up a capacitor by rectifying alternating voltage with a diode and limiting the charging current with a resistor, something that is common knowledge and, among other things, is used in "US 3959695 A" (D2) and "US 4258403 A" (D3). It is also known in D3 that a direct current from a capacitor can be used to release a relay coil, but neither D2 nor D3 use energy stored in a capacitor to deliver short-circuit current directly in an electrical installation.

Krets for vern mot kortslutning er tidlegare nytta til andre bruksområde, der «US 2009168275» Circuit for protection against short circuit is previously used for other areas of use, where "US 2009168275"

(D4) beskriv ein krets som beskyttar ein dynamo mot kortslutning. Sidan dynamo er brukt i isolerte svakstraumsanlegg slik som bilar og mindre båtar, kan kretsen i D4 kan ikkje nyttast direkte mot elektriske installasjonar. Kretsen i D4 gir dessutan berre vern for den enkelte dynamo og bidrar ikkje med kortslutningsstraum til for å sikra funksjonen til eksisterande vern i tilknytt anlegg. (D4) describe a circuit that protects a dynamo against short circuit. Since dynamo is used in isolated low current installations such as cars and small boats, the circuit in D4 cannot be used directly against electrical installations. In addition, the circuit in D4 only provides protection for the individual dynamo and does not contribute with short-circuit current to ensure the function of existing protection in associated facilities.

Ved å bruka kretsen i oppfinninga for å levera kortslutningsstraum, unngår ein ulempene med overdimensjonerte kraftelektroniske omformarar eller avanserte vernløysingar. By using the circuit in the invention to supply short-circuit current, one avoids the disadvantages of oversized power electronic converters or advanced protection solutions.

FIGURAR FIGURES

Figur 1 viser kretsskjema til oppfinninga. Figure 1 shows a circuit diagram of the invention.

Figur 2 viser eksempel på plassering i ein elektrisk installasjon. Figure 2 shows an example of placement in an electrical installation.

Figur 3 viser korleis fleire kretsar for levering av kortslutningsstraum kan brukast i eit trefasa elektrisk anlegg ved hjelp av stjernekopling. Figur 4 viser korleis fleire kretsar for levering av kortslutningsstraum kan brukast i eit trefasa elektrisk anlegg ved hjelp av trekantkopling. Figure 3 shows how several circuits for the supply of short-circuit current can be used in a three-phase electrical installation using a star connection. Figure 4 shows how several circuits for the supply of short-circuit current can be used in a three-phase electrical installation using a delta connection.

DETALJERT BESKRIVELSE DETAILED DESCRIPTION

Krets for å levera kortslutningsstraum til ein elektrisk installasjon erkarakterisert vedat eit energilager i form at ein eller fleire kondensatorar (C) blir lada opp til ei spenning lik nettspenninga sin amplitudeverdi ved hjelp av dioden (D), der motstanden (RI) avgrensar ladestraumen. Når ei kontrolleining (KE) detektera kortslutning i det elektriske anlegget, blir det sendt eit aktiveringssignal halvleiarbrytaren (T), som kan vera ein tyristor eller transistor. Eit slikt aktiveringssignal fører til at halvleiarbrytaren (T) lukkar ein forbindelse mellom kondensatoren (C) og den elektriske installasjonen (LI, L2/N). Spenninga over kondensatoren (C) driv dermed ein kortslutingsstraum i form av ein likestraum ut i det elektriske anlegget, gjennom overstraumsvernet(Fl) og kortslutningspunktet (KS) i den elektriske installasjonen, som vil ha lav impedans. Halvleiarbrytaren (T) blir haldt lukka heilt til likestraumen går til null. Den tilførte kortslutningsstraumen fører til at overstraumsvernet til kursen med feil (Fl) blir aktivert og isolera kursen med feil frå resten av det elektriske anlegget. The circuit for supplying short-circuit current to an electrical installation is characterized by an energy store in the form of one or more capacitors (C) being charged up to a voltage equal to the mains voltage's amplitude value by means of the diode (D), where the resistor (RI) limits the charging current. When a control unit (KE) detects a short circuit in the electrical system, an activation signal is sent to the semiconductor switch (T), which can be a thyristor or transistor. Such an activation signal causes the semiconductor switch (T) to close a connection between the capacitor (C) and the electrical installation (LI, L2/N). The voltage across the capacitor (C) thus drives a short-circuit current in the form of a direct current into the electrical system, through the overcurrent protection (Fl) and the short-circuit point (KS) in the electrical installation, which will have low impedance. The semiconductor switch (T) is kept completely closed until the direct current goes to zero. The supplied short-circuit current causes the overcurrent protection of the circuit with a fault (Fl) to be activated and isolate the circuit with a fault from the rest of the electrical system.

Ved behov, kan kortslutningsstraumen avgrensast med motstanden (R2) for å beskytta kondensatoren (C) mot overstraum. If necessary, the short-circuit current can be limited with the resistor (R2) to protect the capacitor (C) against overcurrent.

Sidan kondensatoren (C) ikkje oppnår større spenning enn amplitudeverdien til nettspenninga ved opplading, kan kretsen ikkje generera skadeleg høg spenning i den elektriske installasjonen ved aktivering. Since the capacitor (C) does not achieve a higher voltage than the amplitude value of the mains voltage when charging, the circuit cannot generate harmful high voltage in the electrical installation when activated.

Levering av kortslutningsstraum i trefasa nett kan gjennomførast ved å kopla tre einingar i stjernekopling som vist i Figur 3, eller trekantkopling som vist i Figur 4. Delivery of short-circuit current in a three-phase network can be carried out by connecting three units in star connection as shown in Figure 3, or delta connection as shown in Figure 4.

Claims (1)

1. Krets for å levera kortslutningsstraum i ein svak eller isolert elektrisk installasjon,karakterisert vedat kortslutningsstraumen blir levert som ein likestraum frå eit energilager beståande av minst ein kondensator (C), der kretsen blir aktivert av halvleiarbrytar (T), og kondensator (C) blir lada opp gjennom diode (D) til ein spenning lik amplitudeverdien i elektriske installasjonen, der motstand (RI) avgrensar ladestraumen.1. Circuit for supplying short-circuit current in a weak or isolated electrical installation, characterized in that the short-circuit current is supplied as a direct current from an energy storage consisting of at least one capacitor (C), where the circuit is activated by a semiconductor switch (T), and capacitor (C) is charged through diode (D) to a voltage equal to the amplitude value in the electrical installation, where resistance (RI) limits the charging current.
NO20150289A 2015-03-03 2015-03-03 Circuit for supply of short-circuit current NO341135B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
NO20150289A NO341135B1 (en) 2015-03-03 2015-03-03 Circuit for supply of short-circuit current

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NO20150289A NO341135B1 (en) 2015-03-03 2015-03-03 Circuit for supply of short-circuit current

Publications (2)

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NO20150289A1 NO20150289A1 (en) 2016-09-05
NO341135B1 true NO341135B1 (en) 2017-08-28

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3959695A (en) * 1975-04-29 1976-05-25 Westinghouse Electric Corporation Circuit interrupter with ground fault trip control
US4258403A (en) * 1979-05-31 1981-03-24 Westinghouse Electric Corp. Ground fault circuit interrupter
US20090168275A1 (en) * 2007-12-28 2009-07-02 Mobiletron Electronics Co., Ltd. Short protection device for alternator
US8058700B1 (en) * 2007-06-07 2011-11-15 Inpower Llc Surge overcurrent protection for solid state, smart, highside, high current, power switch

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3959695A (en) * 1975-04-29 1976-05-25 Westinghouse Electric Corporation Circuit interrupter with ground fault trip control
US4258403A (en) * 1979-05-31 1981-03-24 Westinghouse Electric Corp. Ground fault circuit interrupter
US8058700B1 (en) * 2007-06-07 2011-11-15 Inpower Llc Surge overcurrent protection for solid state, smart, highside, high current, power switch
US20090168275A1 (en) * 2007-12-28 2009-07-02 Mobiletron Electronics Co., Ltd. Short protection device for alternator

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