JP2004317164A - Ground fault detector and ground fault remote monitoring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground fault detector which has a simple and small circuitry with an insulation resistance measuring feature, and a ground fault remote monitoring system using the ground fault detector. <P>SOLUTION: A current transformer CT2 in a detector circuit 20 detects ground current I<SB>O</SB>which refluxes an earthing conductor L<SB>E</SB>by receiving a signal voltage E of a power supply circuit 10. Only low frequency components of the ground fault current I<SB>O</SB>goes through a low-pass filter circuit LF. The ground current I<SB>O</SB>is diverted at the low-pass filter circuit LF to flow into a compensation resistance (r) and a compensation condenser (q). The current (i<SB>r</SB>) flowing into the compensation resistance (r) is transmitted to a phase difference detecting part 2. The phase difference detecting part 2 detects a phase difference between the current (i<SB>r</SB>) flowing into the compensation resistance (r) and the signal voltage E of a power supply circuit 10. A controlling part 3 sends a control signal to make the phase difference to be 0 to the compensation resistance (r) when receiving a detection result signal. As a result, influence of capacitance to the earth is compensated by adjusting the resistance. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００８２】
次に、図７に、地絡故障検出装置１００の検出回路２０と単相３線式電線路とを組合わせた簡易等価回路図を示す。
【００８３】
図７を参照して、検出回路２０は、電線路に配設された、巻数比ｋ_２の変流器ＣＴ２と、補償用抵抗ｒと、補償用コンデンサｑとからなる。
【００８４】
検出回路２０は、変流器ＣＴ２にて信号電圧Ｅの印加によって電線路に駆動された地絡電流Ｉ_０を検出すると、内部に電流ｉ_０を駆動する。電流ｉ_０は、電線路の地絡電流Ｉ_０に比例し、変流器ＣＴ２の巻数比ｋ_２を比例定数として、式（２）で与えられる。
【００８５】
【数２】

【００８６】
したがって、検出回路２０を流れる電流ｉ_０のうち、補償抵抗ｒを流れる電流ｉ_ｒは、式（３）により求めることができる。
【００８７】
【数３】

【００８８】
ここで、式（３）において、電線路の内部インピーダンスと検出回路の内部インピーダンスとの間に、ＣＲ＝ｑｒの関係が成り立てば、電流ｉ_ｒの無効分が「０」となる。これによって、電流ｉ_ｒは、式（４）のように、信号電圧Ｅと同相となる。
【００８９】
【数４】

【００９０】
したがって、式（４）で得られる電流ｉ_ｒより、地絡抵抗Ｒの抵抗値は、式（５）として求めることができる。
【００９１】
【数５】

【００９２】
このとき、電線路に地絡故障が発生していない場合は、式（５）から得られる抵抗値Ｒは、電線路の絶縁抵抗の抵抗値に相当する。
【００９３】
式（５）から明らかなように、電流ｉ_ｒと信号電圧Ｅとの位相差が「０」となった状態では、電流計の指示値と変流器ＣＴ１，ＣＴ２の巻数比ｋ_１，ｋ_２と信号電圧Ｅとから、地絡抵抗Ｒの抵抗値を導出することができる。
【００９４】
ここで、変流器ＣＴ１，ＣＴ２の巻数比ｋ_１，ｋ_２と信号電圧Ｅとは、いずれも固定値であるとから、電流計の目盛板に、電流値に対応する抵抗値を予め印字しておけば、地絡抵抗の値を直接読取ることが可能となる。
【００９５】
以上のように、検出回路２０の補償用抵抗ｒを流れる電流ｉ_ｒと信号電圧Ｅとの位相差が「０」となるように、補償用抵抗ｒと補償用コンデンサｑとの値を調整すれば、対地静電容量に対する充電電流を補償することができ、地絡抵抗Ｒを求めることが可能となる。
【００９６】
なお、本実施の形態では、抵抗値を可変とする補償用抵抗ｒを調整することによって、地絡電流の無効分を補償する構成としたが、補償用抵抗ｒと補償用コンデンサｑとの値をいずれも可変とすること、あるいは補償用コンデンサｑの容量値のみを可変とすることによっても、同様の効果を得ることは明らかである。
【００９７】
最後に、以上の構成および動作原理を備えた本実施の形態の地絡故障検出装置を用いた単相３線式電線路の地絡故障検出例について説明する。
【００９８】
まず、補償動作に先立って、電線路の対地静電容量が地絡電流に及ぼす影響について説明する。
【００９９】
図８は、図１の電源回路１０から供給される信号電圧Ｅと信号電圧Ｅによって接地線Ｌ_Ｅに駆動される地絡電流Ｉ_０との間の位相差の対地静電容量依存性を示す図である。
【０１００】
図８の特性は、電線路の地絡抵抗をＲ＝１ｋΩに設定し、対地静電容量Ｃ（＝Ｃ_１＋Ｃ_２）を１ｐＦから１５０μＦまで変化させたときに得られた特性であり、地絡電流Ｉ_０の電流値および信号電圧Ｅとの位相差の変化を示すものである。
【０１０１】
図８を参照して、電線路の対地静電容量Ｃが１ｐＦと小さいときには、地絡電流Ｉ_０の電流値は１０ｍＡと低く、信号電圧Ｅとの位相差もほぼ０度を示す。
【０１０２】
地絡電流Ｉ_０は、対地静電容量Ｃの増加にしたがって、電流値が増加するとともに、信号電圧Ｅとの位相差も増加する。対地静電容量Ｃが１５０μＦに至っては、地絡電流Ｉ_０は、電流値１４０ｍＡかつ位相差８６度にまで増加する。
【０１０３】
図８の特性が得られた条件下において、検出回路２０にて対地静電容量Ｃによる充電電流を補償しない（補償用抵抗ｒを固定とすることに相当）場合、補償用抵抗ｒを流れる電流ｉ_ｒの対地静電容量依存性は、図９に示す特性となる。
【０１０４】
図９を参照して、補償用抵抗ｒを流れる電流ｉ_ｒは、図８の地絡電流Ｉ_０と同様に、対地静電容量Ｃの増加に伴なって、電流値および信号電圧Ｅとの位相差が増加していく傾向にある。
【０１０５】
そこで、次に、検出回路２０において、対地静電容量Ｃに対する充電電流を補償（補償用抵抗ｒを可変とすることに相当）した場合について示す。
【０１０６】
図１０に、補償用抵抗ｒを流れる電流ｉ_ｒから対地静電容量の影響を補償した結果を示す。
【０１０７】
図１０の特性は、図８および９と同様に、地絡抵抗Ｒを１ｋΩに設定し、対地静電容量Ｃを１ｐＦから１５０μＦまで変化させて得られた特性である。さらにこのとき、補償用抵抗ｒの抵抗値については、５０Ω〜７．５ＭΩの範囲を変化させている。
【０１０８】
図１０から明らかなように、補償用抵抗ｒにおいて、流れる電流ｉ_ｒと信号電圧Ｅとの位相差が「０」となるように抵抗値を調整することにより、補償用抵抗ｒにおける電流ｉ_ｒは、対地静電容量Ｃの増加にかかわらず、電流値１０ｍＡおよび信号電圧Ｅとの位相差０度に保たれる。このことから、電流ｉ_ｒは、対地静電容量Ｃの影響が除去され、地絡抵抗Ｒの抵抗値にのみに依存した値となっていることが分かる。したがって、電流ｉ_ｒの電流値から地絡抵抗Ｒの抵抗値を容易に求めることができる。
【０１０９】
ところで、実際に電線路に地絡故障が発生する場合には、それまで健全であった電線路の絶縁抵抗値が外部要因によって、徐々にまたは突然に低下するものである。そこで、地絡抵抗Ｒの抵抗値が変化したときに、地絡故障検出装置でみられる変化について示す。
【０１１０】
図１１は、地絡電流Ｉ_０および補償用抵抗ｒを流れる電流ｉ_ｒと地絡抵抗Ｒとの関係および補償用抵抗ｒの抵抗値と地絡抵抗Ｒとの関係を示す図である。なお、電線路の対地静電容量Ｃは、１００μＦを示す。
【０１１１】
図１１を参照して、地絡抵抗Ｒの抵抗値が１ｋΩから０．１ｋΩへと低下（変化率９００％に相当）するにしたがって、地絡電流Ｉ_０と補償用抵抗ｒを流れる電流ｉ_ｒとは、いずれも増加する。
【０１１２】
このとき、地絡電流Ｉ_０は、電流値が９４ｍＡから１３７ｍＡへと変化しており、変化率は４６％となる。一方、補償用抵抗ｒを流れる電流ｉ_ｒは、電流値が１０ｍＡから１００ｍＡへと変化しており、変化率は９００％を示す。
【０１１３】
この結果は、地絡電流Ｉ_０が、電線路の対地静電容量に対する充電電流を含んでいるのに対して、補償用抵抗ｒを流れる電流ｉ_ｒは、抵抗値の調整により、対地静電容量に対する充電電流を補償していることから、地絡抵抗Ｒを正確に検出していることを保証している。
【０１１４】
以上のように、この発明の実施の形態１に従えば、電線路の接地線に配した変流器の２次側の検出回路に、地絡電流と対地静電容量に対する充電電流との合成電流を誘起し、該合成電流と電源電圧との位相差をが「０」となるように検出回路内部の補償用抵抗の抵抗値を制御することにより、対地静電容量の影響を補償することができる。
【０１１５】
さらに、補償後の地絡電流から得られた抵抗は、地絡抵抗若しくは絶縁抵抗に相当することから、地絡検出とともに絶縁抵抗測定機能をも備えた地絡故障検出装置が実現される。
【０１１６】
［実施の形態２］
実施の形態１で説明したように、地絡故障検出装置を単相３線式電線路の中性点に接地することによって、電線路における地絡故障を検出することができる。ここで、電線路に地絡故障が発生したことが検出された場合、さらに、故障箇所がどこにあるのかを探索する必要が生じてくる。
【０１１７】
そこで、本実施の形態では、実施の形態１の地絡故障検出装置を用いて、さらに地絡故障箇所を検出する方法について説明する。
【０１１８】
図１２は、この発明の実施の形態２に従う地絡故障検出装置の構成例を示す図である。
【０１１９】
図１２を参照して、単相３線式電線路２００の電線路Ｌ１には、負荷１〜負荷４へと電力を供給するための引出し線Ｌ１−１〜Ｌ１−４が配設されている。引出し線Ｌ１−１〜Ｌ１−４は、それぞれ、対地静電容量Ｃ１〜Ｃ４を含む。
【０１２０】
ここで、前以って、接地線に設置した地絡故障検出装置１００（図示せず）によって、地絡故障が検出されているものとする。この場合、電線路に結合される引出し線ごとに地絡故障検出装置を設置して地絡故障検出を行なえば、地絡故障箇所を特定すことができる。
【０１２１】
図１２では、一例として、引出し線Ｌ１−４に地絡検出装置１００を設置して地絡故障の検出を行なうものとする。
【０１２２】
今、引出し線Ｌ１−４が地絡抵抗Ｒで地絡した場合、引出し線Ｌ１−４と地絡故障検出回路１００とを組合わせた回路構成は、図１３（ａ）の回路図で示される。
【０１２３】
図１３（ａ）を参照して、引出し線Ｌ１−４を流れる地絡電流Ｉ_０は、地絡抵抗Ｒを流れる電流Ｉ_ｇと、引出し線Ｌ１−４の対地静電容量Ｃ４に対する充電電流Ｉ_Ｃとの合成電流となる。
【０１２４】
図１３（ｂ）は、引出し線Ｌ１−４を流れる地絡電流Ｉ_０をベクトル表示した図である。図１３（ｂ）から明らかなように、地絡電流Ｉ_０と信号電圧Ｅとの間には、無効分Ｉ_Ｃによる位相差が生じている。
【０１２５】
この場合も、実施の形態１と同様に、変流器ＣＴ２の２次回路に設けた検出回路２０に地絡電流Ｉ_０を誘起し、補償用抵抗ｒの抵抗値を制御することにより、対地静電容量Ｃ４に対する充電電流成分を補償することができ、地絡抵抗Ｒを流れる電流Ｉ_ｇのみを精度良く検出することができる。
【０１２６】
なお、地絡故障検出装置の詳細な動作については、実施の形態１にて説明したものと共通することから繰り返さない。
【０１２７】
ここで、引出し線Ｌ１−４上に配した地絡故障検出装置１００によって検出された地絡故障は、本検出装置の取付け位置よりも負荷側で発生したものである。
【０１２８】
一方で、地絡故障検出装置１００の取付け位置よりも電源側で地絡が起こった場合、引出し線Ｌ１−４と地絡故障検出回路１００とを組合わせた回路構成は、図１４（ａ）の回路図で表わすことができる。
【０１２９】
図１４（ａ）の回路において、信号電圧Ｅによって引出し線Ｌ１−４に駆動される電流Ｉ_０は、対地静電容量Ｃ４に対する充電電流Ｉ_Ｃのみとなる。
【０１３０】
図１４（ｂ）は、電流Ｉ_０をベクトル表示した図である。同図からも明らかなように、地絡抵抗を流れる有効分はゼロであることから、地絡故障検出装置１００よりも負荷側には、故障箇所がないことが判断できる。
【０１３１】
以上のように、実施の形態２に従えば、地絡故障検出装置を電線路の引出し線に設置することにより、本検出装置の取付け位置に対して負荷側若しくは電源側のいずれかに地絡故障箇所があるのかを判断することができ、地絡発生箇所の特定を行なうことが可能となる。
【０１３２】
［実施の形態３］
以上のように、実施の形態１，２では、本発明に係る地絡故障検出装置を単相３線式電線路の地絡故障検出に用いた場合を例に説明した。本発明に係る地絡故障検出装置は、単相３線式に限定されず、変圧器の低圧側から負荷に電力を供給するための電線路であって、変圧器の中性点にＢ種接地工事が施されているものであれば、その方式にかかわらず適用可能であることは明らかである。具体的には、３相３線式や３相４線式の電線路の地絡故障についても検出可能である。
【０１３３】
そこで、本実施の形態では、図１の地絡故障検出装置を３相３線式電線路に設置して、地絡故障を検出する場合について説明する。
【０１３４】
図１５は、３相３線式電線路３００の回路図である。
図１５を参照して、３相３線式電線路３００は、ａ相，ｂ相，ｃ相の３相からなり、線電流Ｉ_ａ，Ｉ_ｂ，Ｉ_ｃがそれぞれ流れる。中性点は、接地線Ｌ_Ｅによって接地されている。
【０１３５】
ここで、図１５に示すように、１線地絡故障が発生し、ａ相電線がインピーダンスＺ_ｆを通じて地絡したとする。
【０１３６】
１線地絡故障において、ａ相の電圧をＶ_ａとすると、線電流Ｉ_ａ，Ｉ_ｂ，Ｉ_ｃの間には、式（６），（７）の関係が成り立つ。
【０１３７】
【数６】

【０１３８】
【数７】

【０１３９】
零相分電流をＩ_０、正相分電流をＩ_１、逆相分電流をＩ_２とし、式（６），（７）の条件を対称分に書き直すと、式（８）で示す関係が得られる。
【０１４０】
【数８】

【０１４１】
このため、ａ相の電圧Ｖ_ａは、ａ相の起電圧Ｅ_ａ、対称分電圧Ｖ_０，Ｖ_１，Ｖ_２、対称分インピーダンスＺ_０，Ｚ_１，Ｚ_２および式（６）を用いると、式（９）で与えられる。
【０１４２】
【数９】

【０１４３】
さらに、式（９）に式（８）を代入すると、式（１０）となる。
【０１４４】
【数１０】

【０１４５】
ここで、（Ｚ_１＋Ｚ_２）≪（Ｚ_０＋３Ｚ_ｆ）であることから、零相分電流Ｉ_０は、式（１１）で与えられる。
【０１４６】
【数１１】

【０１４７】
また、低圧側の地絡故障では、インピーダンスＺ_ｆは、抵抗成分のみと考えられるため、図１５の３相３線式電線路３００は、図１６（ａ）の零相等価回路で表わすことができる。
【０１４８】
図１６（ａ）は、図１５の３相３線式電線路３００の零相等価回路である。また、本装置は、微地絡故障を検出するためのものであり、その場合には、Ｚ_０≪Ｚ_ｆであるため、零相分電流Ｉ_０をベクトル表示すると、図１６（ｂ）となる。
【０１４９】
図１６（ａ）を参照して、零相分電流Ｉ_０は、地絡抵抗Ｚ_ｆを流れる電流Ｉ_Ｚと、対地静電容量Ｃの充電電流Ｉ_Ｃとの合成電流となる。図１６（ｂ）に示すように、零相分電流Ｉ_０は、対地静電容量Ｃの影響を受けていることが分かる。
【０１５０】
したがって、実施の形態１と同様に、零相分電流Ｉ_０と信号電圧Ｅ_ａとの位相差が「０」となるように、検出回路２０内部の補償用抵抗ｒの抵抗値を制御することにより、対地静電容量Ｃの影響を補償することができる。よって、本実施の形態においても、地絡電流のみを抽出して、地絡故障を検出することができる。
【０１５１】
以上のように、この発明の実施の形態３に従えば、零相電流と信号電圧との位相差を「０」となるように、地絡故障検出装置の補償用抵抗の抵抗値を制御することにより、対地静電容量の影響を補償でき、３相３線式電線路に生じた地絡故障を検出することができる。
【０１５２】
なお、実施の形態１と同様に、補償後の地絡電流から得られた抵抗は、地絡抵抗若しくは絶縁抵抗に相当することから、地絡検出とともに絶縁抵抗測定機能をも備えた地絡故障検出装置が実現される。
【０１５３】
［実施の形態４］
最後に、今回の発明に係る地絡故障検出装置を活用した遠隔監視システムについて説明する。
【０１５４】
図１７は、この発明の実施の形態４に従う地絡故障の遠隔監視システムの構成を示す図である。
【０１５５】
本実施の形態の遠隔監視システムは、各需要家が所有する負荷設備に電力を供給するための受電設備４００において、本発明に係る地絡故障検出装置を配設し、外部の監視センタ４１０から、遠隔的に地絡故障を検出することを目的とする。
【０１５６】
図１７を参照して、複数の需要家の受電設備４００において、変圧器Ｔの低圧側電線路２００の中性点にはＢ種接地工事が施されている。各変圧器Ｔの接地線Ｌ_Ｅには、図１の地絡故障検出装置１００が配設される。
【０１５７】
なお、本実施の形態の遠隔監視システムに用いた各需要家構内の配電系統は、標準的な配電系統の一例である。
【０１５８】
図１７に示すように、配電系統として、図示しない変電所から電力を供給する配電線には、過電流に対する保護として、配電線の故障時に遮断する遮断器ＰＡＳが配置される。遮断器ＰＡＳは、地絡事故発生時において、他の需要家への影響を防止するために、内部の零相変流器ＺＣＴと継電器Ｇとの組合せによって開放される。
【０１５９】
遮断器ＰＡＳを経由した電力は、ケーブルＣＶＴを介して計器用変成器ＰＣＴへと駆動される。計器用変成器ＰＣＴは、交流高電圧を測定するための計器用変圧器ＰＴと、交流大電流を測定するための計器用変流器ＣＴとからなる。計器用変成器ＰＣＴにおいて、交流高電圧（６６００Ｖ）は、２次電圧として低圧（２００Ｖ）に降下される。
【０１６０】
さらに、配電線には、負荷開閉器ＬＢＳが接続される。負荷開閉器ＬＢＳは、変圧器の保守点検時あるいは事故時において、変圧器を配電線から切り離す目的で使用される。
【０１６１】
配電線は、複数の配電線に分岐され、各変圧器Ｔの１次側に高電圧を駆動する。変圧器Ｔの１次側には、電力ヒューズＰＦが結合されており、変圧器Ｔの内部短絡時において、短絡電流を遮断する。なお、配電線には、電力用コンデンサＳＣが結合される。電力用コンデンサＳＣは、誘導性の負荷によって生じる遅れ力率を進ませて、送配電線の力率を改善して電力損失を軽減する目的で使用される。
【０１６２】
各変圧器Ｔでは、１次側の高電圧（６６００Ｖ）が２次側において１００−２００Ｖの配電電圧に変電されると、配電用遮断器ＭＣＢを介して複数の負荷へと伝送される。変圧器Ｔの２次側は、先述のように、単相３線式電線路または３相３線式電線路などで構成され、中性点は接地線Ｌ_Ｅにより接地されている。
【０１６３】
さらに、接地線には、本発明に係る地絡検出装置が設置される。
以上の構成において、地絡故障検出回路１００内部の図示しない電源回路から低周波の信号電圧Ｅが印加されると、接地線Ｌ_Ｅには地絡電流が誘起される。地絡電流は、変流器ＣＴ２で検出されて、図示しない検出回路へと駆動される。
【０１６４】
地絡故障検出装置１００は、各接地線Ｌ_Ｅを流れる地絡電流を常時監視する。検出装置内部では、予め地絡故障の基準となる電流値が設定されている。地絡故障検出装置１００は、対地静電容量の影響を補償した後の地絡電流と設定値とを常時比較する。地絡電流が設定値に達した場合、地絡故障検出回路１００は、地絡故障が発生した電線路を検出し、検出信号を出力する。
【０１６５】
信号伝送装置１１０は、検出信号を受けると、通信回線により監視センタ４１０に警報を発報するともに、需要家の顧客名と故障内容とを監視センタ４１０の画面に表示する。
【０１６６】
監視センタ４１０では、故障内容を保全要員４２０の携帯端末に自動送信して知らせる。
【０１６７】
以上のように、この発明の実施の形態４に従えば、地絡故障検出装置を各需要家の受電設備構内の低圧電線路に設置することにより、各需要家の受電設備に発生し得る地絡故障を常時に監視可能な遠隔監視システムを構築することができる。
【０１６８】
今回開示された実施の形態はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなく、特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。
【０１６９】
【発明の効果】
以上のように、この発明のある局面に従えば、電線路の接地線に配した変流器の２次側の検出回路に、地絡電流と対地静電容量に対する充電電流との合成電流を誘起し、該合成電流と電源電圧との位相差をが「０」となるように検出回路内部の補償用抵抗の抵抗値を制御することにより、対地静電容量の影響を補償することができる。
【０１７０】
さらに、補償後の地絡電流から得られた抵抗は、地絡抵抗若しくは絶縁抵抗に相当することから、地絡検出とともに絶縁抵抗測定機能をも備えた地絡故障検出装置が実現される。
【０１７１】
また、地絡故障検出装置を各需要家の受電設備構内の低圧電線路に設置することにより、各需要家の受電設備に発生し得る地絡故障を常時に監視可能な遠隔監視システムを構築することができる。
【図面の簡単な説明】
【図１】この発明の実施の形態１に従う地絡故障検出装置の構成を示す図である。
【図２】接地線Ｌ_Ｅに還流する地絡電流Ｉ_０をベクトル表示した図である。
【図３】図１の位相差検出部２および制御部３の回路構成の一例を示す図である。
【図４】図１の地絡検出装置１００と単相３線式電線路２００とを一体化したときの零相回路図である。
【図５】図４の単相３線式電線路２００と電源回路１０との組合せに係る零相等価回路図である。
【図６】図５の零相等価回路図を簡略化した零相簡易等価回路図である。
【図７】地絡故障検出装置１００の検出回路２０と単相３線式電線路とを組合わせた簡易等価回路図である。
【図８】信号電圧Ｅと信号電圧Ｅによって接地線Ｌ_Ｅに駆動される地絡電流Ｉ_０との間の位相差の対地静電容量依存性を示す図である。
【図９】補償用抵抗ｒを流れる電流ｉ_ｒの対地静電容量依存性を示す図である。
【図１０】補償用抵抗ｒを流れる電流ｉ_ｒから対地静電容量の影響を補償した結果を示す図である。
【図１１】地絡電流Ｉ_０および補償用抵抗ｒを流れる電流ｉ_ｒと地絡抵抗Ｒとの関係および補償用抵抗ｒの抵抗値と地絡抵抗Ｒとの関係を示す図である。
【図１２】この発明の実施の形態２に従う地絡故障検出装置の構成例を示す図である。
【図１３】引出し線Ｌ１−４と地絡故障検出回路１００とを組合わせた回路構成（図１３（ａ））と、引出し線Ｌ１−４に流れる地絡電流Ｉ_０をベクトル表示した図（図１３（ｂ））とである。
【図１４】引出し線Ｌ１−４と地絡故障検出回路１００とを組合わせた回路構成（図１４（ａ））と、引出し線Ｌ１−４を流れる電流Ｉ_０をベクトル表示した図（図１４（ｂ））とである。
【図１５】３相３線式電線路３００の回路図である。
【図１６】図１５の３相３線式電線路３００の零相等価回路図（図１６（ａ））と、零相分電流Ｉ_０をベクトル表示した図（図１６（ｂ））とである。
【図１７】この発明の実施の形態４に従う地絡故障の遠隔監視システムの構成を示す図である。
【図１８】特許文献１に記載される従来の絶縁抵抗測定装置の一例の構成を示す概略ブロック図である。
【符号の説明】
１ 電源、２ 位相差検出部、３ 制御部、４ 電流計、５ リレー回路、１０ 電源回路、２０ 検出回路、Ｌ_Ｅ 接地線、Ｌ１，Ｌ２ 電線路、Ｒ 地絡抵抗、Ｃ１，Ｃ２，Ｃ 対地静電容量、Ｔ，ＯＴ 変圧器、ＣＴ１，ＣＴ２ 変流器、Ｍ サーボモータ、ｒ 補償用抵抗、ｑ 補償用コンデンサ、ＯＰ１〜ＯＰ５ 演算増幅器、Ｒ１〜Ｒ１４ 抵抗、ＰＡＳ 遮断器、Ｇ 継電器、ＣＶＴケーブル、ＰＣＴ 計器用変成器、ＬＢＳ 負荷開閉器、ＰＦ 電力ヒューズ、ＳＣ 電力用コンデンサ、ＭＣＢ 配電用遮断器、、ＺＣＴ 零相変流器、ＡＭＰ 増幅器、ＦＩＬ フィルタ回路、ＤＥＴ 整流回路、ＯＳＣ 発振器、Ｌ_Ｐ ループ接地線、１００ 地絡故障検出回路、１１０ 信号伝送装置、２００単相３線式電線路、３００ ３相３線式電線路、４００ 受電設備、４１０ 監視センタ、４２０ 保全要員。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a ground fault detection device and a ground fault remote monitoring system, and more particularly to a ground fault detection device and a ground fault remote monitoring system having an insulation resistance measuring function.
[0002]
[Prior art]
In the case of a low-voltage line such as a three-phase three-wire system, a three-phase four-wire system, or a single-phase three-wire system, when there is a risk that high voltage or extra high voltage may be mixed with low voltage, the purpose is to protect the low piezoelectric path. Class B grounding work is performed to ground the neutral point of the transformer with a ground wire.
[0003]
For this reason, in such an electric wire path, when detecting a ground fault or measuring insulation resistance in a live state, it is common to use a ground wire for class B grounding work. .
[0004]
However, when the ground fault is detected by the above method, the ground fault current flowing from the ground fault point of the power line to the ground wire via the ground is added to the current component due to the ground fault resistance, Since the charging current for the ground capacitance is included, it is necessary to accurately detect the current component due to the ground fault resistance.
[0005]
In addition, since the ground capacitance of the electric line constantly fluctuates depending on the connection state of the load to the low-voltage line and the operation state of the device, the influence of the fluctuating ground capacitance is reliably excluded from the ground fault current. It is desirable.
[0006]
In view of these needs, various methods for removing the influence of the earth capacitance have been proposed in the conventional ground fault detection device and insulation monitoring device (for example, Patent Documents 1, 2, and 2). 3).
[0007]
FIG. 18 is a schematic block diagram showing a configuration of an example of a conventional insulation resistance measuring device described in Patent Document 1.
[0008]
Referring to FIG. 18, the ground fault detecting device includes a grounding line L of a power receiving transformer T having a load Z._EOT, a zero-phase current transformer ZCT, an oscillator OSC for oscillating a low-frequency signal for measurement having a frequency lower than the commercial frequency, an amplifier AMP, a filter FIL, and a rectifier DET.
[0009]
The insulation resistance measuring device further includes a loop ground line L passing through the transformer OT and the zero-phase current transformer ZCT._PAnd the loop ground line L_PVariable capacitor C connected in series to_VAnd variable resistor R_VAnd a parallel circuit comprising:
[0010]
Note that the loop ground line L_PIs the ground line L_EThe leakage current flowing through the_C0′ Are arranged to penetrate the transformer OT and the zero-phase current transformer ZCT.
[0011]
In this configuration, the measurement low-frequency signal output from the oscillator OSC is transmitted from the transformer OT to the ground line L._ETo the ground line L_EHas an electric line L₁Insulation resistance R₀And ground capacitance C₀And the ground line L_ELeakage current I returning to_C0+ I_R0Is induced. Where I_C0Is a charging current for the ground capacitance C0, and I_R0Is the insulation resistance R of the wireway₀Is the current flowing through
[0012]
Leakage current I_C0+ I_R0Is the ground line L_EIs output to the zero-phase current transformer ZCT from the output terminal OUT via the amplifier AMP, the filter FIL, and the rectifier circuit DET connected thereto.
[0013]
On the other hand, the loop ground line L_PHas a leakage current I due to a measurement low-frequency signal applied from the transformer OT._C0+ I_R0Current I in opposite phase to_C0′ Is induced and the variable capacitor C_VAnd variable resistor R_VFlows through a parallel circuit consisting of Therefore, the current I_C0’Is a variable resistor R_VCurrent I flowing through_RVAnd the variable capacitor C_VCurrent I flowing through_CVAnd the combined current.
[0014]
Further, the loop ground line L_PPasses through the zero-phase current transformer ZCT, so that the current I_C0'Is output from the output terminal OUT via the amplifier AMP, the filter FIL, and the rectifier circuit DET, similarly to the leakage current.
[0015]
Therefore, the output terminal OUT has the leakage current I_C0+ I_R0And the current I in opposite phase_C0′ Are output. Since both currents are in a mutually canceling relationship, the variable resistor R_VAnd variable capacitor C_VIs adjusted, the absolute value of the combined current is minimized. The variable resistor R at this time_VAnd variable capacitor C_VIs the insulation resistance R of the wireway₀And capacitance C to ground₀Is equivalent to the insulation resistance R₀Can be obtained.
[0016]
[Patent Document 1]
JP-A-60-165559 (page 2, FIG. 3)
[0017]
[Patent Document 2]
JP-A-10-78461 (page 2, FIG. 1)
[0018]
[Patent Document 3]
JP-A-2002-125313 (page 3, FIG. 1)
[0019]
[Problems to be solved by the invention]
The conventional insulation resistance measuring device shown in FIG. 18 generates a current having a phase opposite to the leakage current in the zero-phase current transformer, and the two currents cancel each other, so that the current flowing through the zero-phase current transformer is minimized. Thus, the influence of the capacitance to the ground is removed by controlling so that
[0020]
On the other hand, the conventional insulation resistance measuring device has a problem that it is not suitable for detecting a ground fault that requires constant monitoring because the insulation resistance is measured by operating the measuring device on site. For these reasons, conventionally, the ground fault detecting device and the insulation resistance measuring device are provided independently of each other and need to be used properly according to the purpose.
[0021]
In addition, the insulation resistance measurement device described in Patent Document 3 (not shown) requires a vector operation circuit for calculating the ground fault effective current in the zero-phase current transformer inside the measurement device. In addition to the complicated configuration, there has been a problem that the circuit scale is increased. This problem is disadvantageous also in terms of cost, and has been a factor that hinders generalization.
[0022]
SUMMARY OF THE INVENTION Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to provide a ground fault detecting apparatus having a simple and small-scale circuit configuration and also having an insulation resistance measuring function. And to provide a ground fault remote monitoring system using the ground fault detecting device.
[0023]
[Means for Solving the Problems]
According to an aspect of the present invention, there is provided a ground fault detection device for detecting a ground fault occurring in a low-voltage line, and a ground line disposed at a neutral point of a transformer of the low-voltage line, The power supply circuit includes a power supply circuit that applies a signal voltage having a frequency lower than the commercial frequency, and a detection circuit that detects a ground fault based on a ground fault current returned from the low piezoelectric line to the ground line according to the signal voltage. The detection circuit includes a current transformer that is arranged on the ground line and induces a ground fault current inside the detection circuit, and a resistance element and a capacitance element that are connected in parallel, and is induced by the current transformer and driven by the resistance element. A compensating circuit for compensating for an ineffective component of the ground fault current, a phase difference detecting unit for detecting a phase difference between the ground fault current driven by the resistance element and the signal voltage, and outputting a detection result signal; The value of the resistance element and the capacitance element of the compensation circuit are controlled based on the detection result signal of the detection unit, and the phase difference between the ground fault current driven by the resistance element and the signal voltage is controlled to be zero. Ground fault detection that constantly monitors the current value of the ground fault current driven by the control unit and the resistive element whose ineffectiveness has been compensated, and detects a ground fault when a predetermined current value is exceeded and issues an alarm. Unit.
[0024]
Preferably, the control unit controls one or both of the resistance value of the resistance element and the capacitance value of the capacitance element of the compensation circuit based on the detection result signal of the phase difference detection unit.
[0025]
More preferably, the ground fault detection unit includes a resistance measuring unit that measures a ground fault resistance or an insulation resistance of the low piezoelectric line based on a current value of a ground fault current driven by the resistance element whose ineffective component has been compensated. Further prepare.
[0026]
According to another aspect of the present invention, a ground fault detecting means for detecting a ground fault occurring in the low-voltage line, and detecting a ground fault in the low-voltage line, a branch point of the low-voltage line and A ground fault detecting unit that is disposed on each of the plurality of leads connecting to the load, detects a ground fault occurring in each of the plurality of leads, and specifies a ground fault location based on the detection result. . The ground fault detecting means includes: a first power supply circuit for applying a signal voltage of a frequency lower than the commercial frequency to a ground wire disposed at a neutral point of the transformer of the low-voltage line; A first detection circuit for detecting a ground fault based on a ground fault current returned from the low-voltage line to the ground line. The ground fault location detecting means includes: a second power supply circuit for applying a signal voltage having a frequency lower than the commercial voltage to the lead, and a ground fault current that is returned from the ground to the lead according to the signal voltage. And a second detection circuit for detecting a ground fault based on The first and second detection circuits are arranged on the ground line and the lead line, respectively, include a current transformer for inducing a ground fault current inside the detection circuit, and a resistance element and a capacitance element connected in parallel. A compensating circuit for compensating for an ineffective part of the ground fault current driven by the resistance element induced by the current transformer, and detecting and detecting a phase difference between the ground fault current driven by the resistance element and the signal voltage. A phase difference detection unit that outputs a result signal, and a ground fault current and a signal that are driven by the resistance element by controlling values of the resistance element and the capacitance element of the compensation circuit based on the detection result signal of the phase difference detection unit. A control unit that controls the phase difference with the voltage to be zero, and a current value of the ground fault current driven by the resistance element whose ineffective component has been compensated is constantly monitored, and when the current value exceeds a predetermined current value, the ground level is monitored. A ground fault detection unit that detects a ground fault and issues an alarm.
[0027]
Preferably, the control unit controls one or both of the resistance value of the resistance element and the capacitance value of the capacitance element of the compensation circuit based on the detection result signal of the phase difference detection unit.
[0028]
According to another aspect of the present invention, there is provided a ground fault fault remote management system for remotely monitoring and detecting a ground fault occurring in a power receiving facility of each of a plurality of consumers, A ground fault detector that is grounded to the neutral point of a low-voltage line transformer in the power receiving facility premises, a signal transmission device that transmits an alarm that the ground fault detector detects and issues a ground fault, and It is located remotely from the power receiving equipment of a plurality of customers, constantly monitors the alarm transmitted from the signal transmission device of each of the plurality of customers, and dispatches maintenance personnel to the power receiving equipment of the customer where the alarm is detected. And a monitoring center. The ground fault detection device is a power supply that applies a signal voltage of a frequency lower than the commercial frequency to a ground line disposed at a neutral point of a transformer of a low-voltage line in a power receiving facility of each of a plurality of customers. And a detection circuit that detects a ground fault based on a ground fault current returned from the power line to the ground line according to the signal voltage. The detection circuit includes a current transformer that is arranged on the ground line and induces a ground fault current inside the detection circuit, and a resistance element and a capacitance element that are connected in parallel, and is induced by the current transformer and driven by the resistance element. A compensating circuit for compensating for an ineffective component of the ground fault current, a phase difference detecting unit for detecting a phase difference between the ground fault current driven by the resistance element and the signal voltage, and outputting a detection result signal; The value of the resistance element and the capacitance element of the compensation circuit are controlled based on the detection result signal of the detection unit, and the phase difference between the ground fault current driven by the resistance element and the signal voltage is controlled to be zero. Ground fault detection that constantly monitors the current value of the ground fault current driven by the control unit and the resistance element whose ineffectiveness has been compensated, and detects a ground fault when a predetermined current value is exceeded and issues an alarm. Parts.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.
[0030]
[Embodiment 1]
FIG. 1 is a diagram showing a configuration of a ground fault detection device according to the first embodiment of the present invention. In the present embodiment, a case where the ground fault detection device 100 is applied to the detection of a ground fault in the single-phase three-wire electric line 200 will be described as an example.
[0031]
Referring to FIG. 1, class B grounding is performed on transformer T of single-phase three-wire electric line 200, and neutral point is ground line L._EGrounded.
[0032]
The single-phase three-wire electric line 200 is an electric line for driving a low voltage on the secondary side of the transformer T to a load, and each electric line L₁, L₂Is the ground capacitance C₁, C₂Having.
[0033]
Electric line L₁Is the resistance R₁Is a ground fault resistance at a fault point when a ground fault occurs in the first embodiment. Therefore, when a ground fault occurs, the power line L₁Ground fault current I₀Flows in. Ground fault current I_oIs further connected to the ground line L from the ground._EReflux.
[0034]
FIG. 2 shows the ground line L_EGround current I flowing back to₀FIG. 5 is a vector display.
As shown in FIG.₀Is an effective component I in phase with the signal voltage E._gAnd an invalid component (I_C1+ I_C2).
[0035]
Here, the effective component I_g1 corresponds to the current flowing through the ground fault resistance R at the ground fault point of the electric line in the single-phase three-wire electric line shown in FIG. On the other hand, the invalid portion (I_C1+ I_C2) Indicates the ground capacitance C of each electric line.₁, C₂Corresponding to the sum of the charging currents.
[0036]
Therefore, the ground fault current I flowing through the ground fault resistance R_gIn order to obtain the₀From the invalid part (I_C1+ I_C2) Must be removed.
[0037]
The ground fault detection device according to the present embodiment proposes a method for realizing the removal of the influence of the ground capacitance. Hereinafter, the configuration and operation of the ground fault detection circuit will be described in detail.
[0038]
The ground fault detection device 100 is disposed at the neutral point of the single-phase three-wire electric line 200, and is roughly classified into a power supply circuit 10 and a detection circuit 20. Both the power supply circuit 10 and the detection circuit 20 are connected to the ground line L of the single-phase three-wire electric line 200 via the current transformers CT1 and CT2._EIs combined with
[0039]
The power supply circuit 10 includes a ground line L_EIs a primary conductor, a through-type current transformer CT1 and a ground wire L via the current transformer CT1._EAnd a power supply 1 for applying a signal voltage E to the power supply.
[0040]
As described later, a signal voltage E of a specific frequency is supplied from the power supply 1 of the power supply circuit 10 to the ground line L._EIs applied to the ground line L when a ground fault occurs._ETo the ground fault current I at a specific frequency₀Is refluxed.
[0041]
Here, when a ground fault occurs in the single-phase three-wire electric line 200, a zero-phase voltage of a commercial frequency is generated. Therefore, when a commercial frequency power supply is used for the power supply circuit 10, the signal voltage E is affected by interference with the zero-phase voltage. Therefore, the frequency of the signal voltage E needs to be different from the commercial frequency.
[0042]
Furthermore, since the charging current for the capacitance of the electric line relative to the ground increases in proportion to the frequency, the frequency of the signal voltage E is set lower than the commercial frequency to suppress the charging current.
[0043]
The detection circuit 20 includes a ground line L_E, A compensating circuit including a compensating resistor r and a compensating capacitor q for varying the resistance value, an ammeter 4, and a phase difference detection. It comprises a unit 2 and a control unit 3.
[0044]
The current transformer CT2 receives the signal voltage E and_EGround fault current I driven₀Is detected and transmitted to the inside of the detection circuit 20.
[0045]
The current transformer CT2 is connected to a low-pass filter circuit LF that extracts only low-frequency components of the input signal. The low-pass filter circuit LF outputs the detected ground fault current I₀, The high frequency commercial frequency component is removed, and only the specific frequency component is passed.
[0046]
A compensation circuit is coupled to an output node of the low-pass filter circuit LF. The compensation circuit calculates the ground fault current I₀This is a circuit for compensating for the influence of the ground capacitance. The compensating circuit includes a compensating capacitor q, a compensating resistor r, and an ammeter 4 for measuring a current value flowing through the compensating resistor r.
[0047]
The ground fault current I input from the low-pass filter circuit LF to the compensation circuit₀Is shunted to a compensating resistor r and a compensating capacitor q. Among them, the current i flowing through the compensation resistor r_rIs further transmitted to the phase difference detection unit 2.
[0048]
The phase difference detector 2 detects the current i flowing through the compensation resistor r._rAnd the signal voltage E from the power supply circuit 10, the phase difference between them is detected. The detected phase difference is further input to the control unit 3 as a detection result signal. Upon receiving the detection result signal, the control unit 3 inputs a control signal that sets the detected phase difference to “0” to the compensation resistor r to adjust the resistance value. Here, a detailed configuration of the phase difference detection unit 2 and the control unit 3 will be described below.
[0049]
FIG. 3 is a diagram illustrating an example of a circuit configuration of the phase difference detection unit 2 and the control unit 3 in FIG.
[0050]
Referring to FIG. 3, phase difference detection section 2 includes a current / voltage conversion section, a comparator, and a differential amplifier, and receives a voltage input (corresponding to signal voltage E) from power supply circuit 10 and detection circuit 20. (Current i in compensation resistor r)_r) Is detected.
[0051]
The current / voltage converter is provided on the current input side of the phase difference detector 2, and includes an operational amplifier OP1 and resistors R1 and R2. Assuming that the operational amplifier OP1 is ideal, the input current i_rIs converted to an output voltage that is a product of the resistance R2 connected in negative feedback.
[0052]
The comparator includes an operational amplifier OP2 receiving the signal voltage E and a current / voltage-converted current I_r, And an operational amplifier OP3 that receives the current, and resistors R3 to R8.
[0053]
When the sine wave signal voltage E is input, the operational amplifier OP2 compares it with the zero voltage, that is, determines the polarity, and outputs a rectangular wave signal having a binary potential level as a comparison result.
[0054]
Similarly, in the operational amplifier OP3, the voltage-converted current I_rUpon receiving the signal, the polarity is determined and a rectangular wave comparison result signal having a binary potential level is output.
[0055]
Output signals from the operational amplifiers OP2 and OP3 are input to a differential amplifier at a subsequent stage. The differential amplifier includes an operational amplifier OP4 and resistors R9 to R12. The output signals of the operational amplifiers OP2 and OP3 are input to the inverting input terminal and the non-inverting input terminal of the operational amplifier OP4 via the resistors R9 and R10, respectively. The differential amplifier amplifies only the phase difference between the two input signals and transmits the result to the control unit 3 as a detection result signal.
[0056]
The control unit 3 includes a servo motor drive unit for controlling the resistance value of the compensating resistor r, which is a variable resistor.
[0057]
The servo motor driving unit receives the detection result signal from the differential amplifier of the phase difference detection unit 2 via an inverting input terminal via a resistor R13, and receives a ground potential at a non-inverting input terminal, and an operational amplifier OP5. And
[0058]
The resistor R14 is connected between the inverting input terminal and the output terminal of the operational amplifier OP5, and an output signal whose potential is proportional to the ratio of the resistors R13 and R14 is output to the output terminal.
[0059]
The output signal of the operational amplifier OP5 is input to the servo motor M at the subsequent stage. The servo motor M changes the resistance value of the compensating resistor r by performing a linear or rotational movement using the output signal from the operational amplifier OP5 as power. At this time, the current i_rIs higher than the signal voltage E, the resistance value of the compensation resistor r is increased. On the other hand, the current i_rIs smaller than the signal voltage E, the resistance value of the compensating resistor r is reduced.
[0060]
Thus, the signal voltage E and the current I_rIs zero, the current i flowing through the compensation resistor r_rFrom the ground capacitance C₁, C₂Will be removed.
[0061]
Therefore, the current i_rIs an effective current that is proportional to the turns ratio of the current transformers CT1 and CT2 and the ground fault resistance R, as described later, so that the resistance value of the ground fault resistor R can be obtained from the current value.
[0062]
In addition, when the ground fault does not occur in the electric line, the obtained resistance value corresponds to the insulation resistance of the electric line, so the ground fault detecting device of the present embodiment is used as an insulation resistance measuring device. It also has the function of
[0063]
Furthermore, if the ammeter 4 in the detection circuit 10 is provided with an alarm contact and an alarm is issued when the resistance value becomes equal to or less than a predetermined insulation resistance value, the occurrence of leakage due to insulation deterioration is detected. As a result, it is possible to obtain a ground fault detection device that is constantly monitored.
[0064]
Next, the operation principle of the ground fault detection device of the present embodiment shown in FIG. 1 will be described in more detail.
[0065]
FIG. 4 is a zero-phase circuit diagram when the ground fault detection device 100 of FIG. 1 and the single-phase three-wire electric line 200 are integrated.
[0066]
Referring to FIG. 4, the zero-phase circuit of single-phase three-wire electric line 200 has a zero-phase resistance r.₀And zero-phase reactance X₀And an external impedance Z comprising a ground capacitance C and a ground fault resistance R.
[0067]
Current transformers CT1 and CT2 are provided on the single-phase three-wire electric line. The turns ratio of the current transformers CT1 and CT2 is k₁, K₂And
[0068]
In the ground fault detection device 100, the power supply circuit 10 includes a current transformer CT1, a power supply E, and an internal resistance r.₁And the internal reactance X₁And represented by
[0069]
On the other hand, the detection circuit 20 includes a current transformer CT2, a compensating resistor r, a compensating capacitor q, and an internal resistor r.₂And the internal reactance X₂And represented by
[0070]
In this configuration, the ground fault current I is applied to the single-phase three-wire electric line 200 by the signal voltage E applied from the power supply circuit 10 via the current transformer CT1.₀Is induced.
[0071]
Ground fault current I₀Is detected by the current transformer CT2 of the detection circuit 20, and is divided into a compensation capacitor q and a compensation resistor r inside the detection circuit 10. The compensation resistor r has a current i_rFlows.
[0072]
Here, the zero-phase equivalent circuit according to the combination of the single-phase three-wire electric line 200 and the power supply circuit 10 in FIG. 4 is given by the circuit diagram in FIG.
[0073]
Referring to FIG. 5, the internal impedance of single-phase three-wire electric line 200 is determined by the turns ratio k of current transformer CT1.₁And the zero-phase resistance k₁ ²r₀And zero-phase reactance k₁ ²X₀And represented by The external impedance is k₁ ²Given by Z.
[0074]
Current I flowing through power supply circuit 10₀’Is the turns ratio k₁Is the proportionality constant, I₀/ K₁Given by
[0075]
The current transformer CT1 is represented by reactance and resistance, and has an internal admittance Y.
[0076]
Here, the internal impedance of the power supply circuit 10 of FIG. 5 and the internal impedance of the zero-phase circuit of the single-phase three-wire electric line 200 are represented by an external impedance k constituted by a ground fault resistance R and a ground capacitance C.₁ ²These are ignored because they are sufficiently small with respect to Z. Further, the internal admittance Y of the current transformer CT1 is also a very small value, and is therefore similarly ignored.
[0077]
As a result, the zero-phase equivalent circuit of FIG. 5 can be further simplified to a zero-phase simple equivalent circuit diagram of FIG.
[0078]
As shown in FIG. 6, the zero-phase circuit of the power supply circuit 10 and the single-phase three-wire system 200 has a signal voltage E of the power circuit 10 and an internal impedance k₁ ²And Z.
[0079]
At this time, the current I flowing through the circuit₀’Is the ground fault current I₀And the turns ratio k of the current transformer CT1₁From I₀’= I₀/ K₁Becomes
[0080]
Therefore, the ground fault current I₀Is the signal voltage E and the internal impedance k of the power line₁ ²From Z, it is given by equation (1).
[0081]
(Equation 1)

[0082]
Next, FIG. 7 shows a simplified equivalent circuit diagram in which the detection circuit 20 of the ground fault detection device 100 and a single-phase three-wire electric line are combined.
[0083]
Referring to FIG. 7, detection circuit 20 is provided with a turns ratio k,₂, A compensating resistor r, and a compensating capacitor q.
[0084]
The detection circuit 20 detects the ground fault current I driven to the electric line by the application of the signal voltage E by the current transformer CT2.₀Is detected, the current i₀Drive. Current i₀Is the ground fault current I₀And the turns ratio k of the current transformer CT2₂Is given by Expression (2), where is a proportional constant.
[0085]
(Equation 2)

[0086]
Therefore, the current i flowing through the detection circuit 20₀Of the current i flowing through the compensation resistor r_rCan be obtained by Expression (3).
[0087]
(Equation 3)

[0088]
Here, in equation (3), if a relationship of CR = qr is established between the internal impedance of the power line and the internal impedance of the detection circuit, the current i_rBecomes "0". As a result, the current i_rBecomes in-phase with the signal voltage E as in the equation (4).
[0089]
(Equation 4)

[0090]
Therefore, the current i obtained by equation (4)_rThus, the resistance value of the ground fault resistance R can be obtained as Expression (5).
[0091]
(Equation 5)

[0092]
At this time, when no ground fault has occurred in the electric line, the resistance value R obtained from Equation (5) corresponds to the resistance value of the insulation resistance of the electric line.
[0093]
As is clear from equation (5), the current i_rWhen the phase difference between the current and the signal voltage E is “0”, the indicated value of the ammeter and the turns ratio k of the current transformers CT1 and CT2 are k.₁, K₂And the signal voltage E, the resistance value of the ground fault resistor R can be derived.
[0094]
Here, the turns ratio k of the current transformers CT1, CT2₁, K₂Since both the signal voltage E and the signal voltage E are fixed values, it is possible to directly read the value of the ground fault resistance by printing the resistance value corresponding to the current value on the scale plate of the ammeter in advance. Become.
[0095]
As described above, the current i flowing through the compensation resistor r of the detection circuit 20_rIf the values of the compensating resistor r and the compensating capacitor q are adjusted so that the phase difference between the signal and the signal voltage E becomes “0”, the charging current with respect to the ground capacitance can be compensated, The resistance R can be obtained.
[0096]
In this embodiment, the ineffective component of the ground fault current is compensated by adjusting the compensating resistor r which makes the resistance value variable. However, the value of the compensating resistor r and the compensating capacitor q is adjusted. It is apparent that the same effect can be obtained by making any of these variables variable, or by making only the capacitance value of the compensating capacitor q variable.
[0097]
Lastly, a description will be given of an example of detecting a ground fault in a single-phase three-wire electric line using the ground fault detecting device of the present embodiment having the above configuration and operation principle.
[0098]
First, prior to the compensation operation, the effect of the capacitance of the power line to ground on the ground fault current will be described.
[0099]
FIG. 8 shows a signal line E supplied from the power supply circuit 10 of FIG._EGround fault current I driven₀FIG. 4 is a diagram illustrating the dependence of the phase difference between the ground capacitance and the ground capacitance.
[0100]
The characteristic of FIG. 8 is that the ground fault resistance of the electric line is set to R = 1 kΩ, and the ground capacitance C (= C₁+ C₂) Is changed from 1 pF to 150 μF.₀And the change in the phase difference between the current value and the signal voltage E.
[0101]
Referring to FIG. 8, when the ground capacitance C of the electric line is as small as 1 pF, the ground fault current I₀Has a low value of 10 mA, and the phase difference with the signal voltage E also shows almost 0 degrees.
[0102]
Ground fault current I₀As the current value increases as the ground capacitance C increases, the phase difference with the signal voltage E also increases. When the ground capacitance C reaches 150 μF, the ground fault current I₀Increases to a current value of 140 mA and a phase difference of 86 degrees.
[0103]
Under the condition that the characteristic of FIG. 8 is obtained, when the charging current due to the ground capacitance C is not compensated by the detection circuit 20 (corresponding to fixing the compensation resistor r), the current flowing through the compensation resistor r i_rIs the characteristic shown in FIG.
[0104]
Referring to FIG. 9, current i flowing through compensation resistor r_rIs the ground fault current I of FIG.₀Similarly, as the capacitance C to the ground increases, the phase difference between the current value and the signal voltage E tends to increase.
[0105]
Therefore, next, a case will be described in which the detection circuit 20 compensates the charging current for the ground capacitance C (corresponding to making the compensation resistor r variable).
[0106]
FIG. 10 shows the current i flowing through the compensation resistor r._r5 shows the result of compensating for the influence of the ground capacitance.
[0107]
The characteristic of FIG. 10 is a characteristic obtained by setting the ground fault resistance R to 1 kΩ and changing the ground capacitance C from 1 pF to 150 μF, similarly to FIGS. 8 and 9. Further, at this time, the resistance value of the compensating resistor r is changed in the range of 50Ω to 7.5MΩ.
[0108]
As is apparent from FIG. 10, the current i flowing through the compensation resistor r_rThe resistance i is adjusted so that the phase difference between the signal voltage E and the signal voltage E becomes "0"._rIs maintained at a current value of 10 mA and a phase difference of 0 degree from the signal voltage E irrespective of an increase in the ground capacitance C. From this, the current i_rIt can be seen from the graph that the influence of the capacitance C to the ground is removed and the value depends only on the resistance value of the ground fault resistance R. Therefore, the current i_rThe resistance value of the ground fault resistor R can be easily obtained from the current value.
[0109]
When a ground fault actually occurs in an electric line, the insulation resistance value of the previously healthy line is gradually or suddenly decreased due to an external factor. Therefore, a change observed in the ground fault detection device when the resistance value of the ground fault resistor R changes will be described.
[0110]
FIG. 11 shows the ground fault current I₀And current i flowing through compensation resistor r_rFIG. 6 is a diagram showing a relationship between the ground fault resistance R and a resistance value of the compensation resistor r and the ground fault resistance R. Note that the capacitance C of the electric wire path to ground indicates 100 μF.
[0111]
Referring to FIG. 11, as the resistance value of ground fault resistor R decreases from 1 kΩ to 0.1 kΩ (corresponding to a change rate of 900%), ground fault current I increases.₀And the current i flowing through the compensation resistor r_rAnd both increase.
[0112]
At this time, the ground fault current I₀The current value has changed from 94 mA to 137 mA, and the rate of change is 46%. On the other hand, the current i flowing through the compensation resistor r_rIndicates that the current value has changed from 10 mA to 100 mA, and the rate of change indicates 900%.
[0113]
The result is that the ground fault current I₀Contains the charging current for the earth capacitance of the electric line, while the current i flowing through the compensating resistor r_rCompensates for the charging current with respect to the ground capacitance by adjusting the resistance value, and thus guarantees that the ground fault resistance R is accurately detected.
[0114]
As described above, according to the first embodiment of the present invention, the detection circuit on the secondary side of the current transformer arranged on the ground line of the power line has a combination of the ground fault current and the charging current with respect to the ground capacitance. Compensating for the influence of the ground capacitance by inducing a current and controlling the resistance value of a compensation resistor inside the detection circuit so that the phase difference between the combined current and the power supply voltage becomes “0”. Can be.
[0115]
Furthermore, since the resistance obtained from the compensated ground fault current corresponds to the ground fault resistance or the insulation resistance, a ground fault detection device having a ground fault detection and an insulation resistance measurement function is realized.
[0116]
[Embodiment 2]
As described in the first embodiment, by grounding the ground fault detecting device to the neutral point of the single-phase three-wire electric line, a ground fault in the electric line can be detected. Here, when it is detected that a ground fault has occurred in the electric wire path, it is necessary to further search for a fault location.
[0117]
Therefore, in the present embodiment, a method of further detecting a ground fault location using the ground fault detection device of the first embodiment will be described.
[0118]
FIG. 12 is a diagram showing a configuration example of a ground fault detection device according to the second embodiment of the present invention.
[0119]
Referring to FIG. 12, lead lines L1-1 to L1-4 for supplying electric power to loads 1 to 4 are provided in electric line L1 of single-phase three-wire electric line 200. . The lead lines L1-1 to L1-4 include ground capacitances C1 to C4, respectively.
[0120]
Here, it is assumed that the ground fault has been detected by the ground fault detecting device 100 (not shown) installed on the ground wire in advance. In this case, if a ground fault detection device is installed for each lead wire connected to the electric wire and ground fault detection is performed, a ground fault location can be specified.
[0121]
In FIG. 12, as an example, it is assumed that the ground fault detecting device 100 is installed on the lead line L1-4 to detect a ground fault.
[0122]
Now, in the case where the lead line L1-4 is grounded due to the ground fault resistance R, a circuit configuration in which the lead line L1-4 and the ground fault detection circuit 100 are combined is shown in the circuit diagram of FIG. .
[0123]
Referring to FIG. 13A, ground fault current I flowing through lead line L1-4 is provided.₀Is the current I flowing through the ground fault resistance R._gAnd the charging current I to the ground capacitance C4 of the lead line L1-4._CAnd the combined current.
[0124]
FIG. 13B shows a ground fault current I flowing through the lead line L1-4.₀FIG. 5 is a vector display. As is clear from FIG. 13B, the ground fault current I₀And the signal voltage E, there is an invalid component I_CCauses a phase difference.
[0125]
Also in this case, similarly to the first embodiment, the ground fault current I is supplied to the detection circuit 20 provided in the secondary circuit of the current transformer CT2.₀By controlling the resistance value of the compensating resistor r, the charging current component with respect to the ground capacitance C4 can be compensated, and the current I flowing through the ground fault resistor R can be compensated._gCan be accurately detected.
[0126]
The detailed operation of the ground fault detection device is not repeated since it is common to that described in the first embodiment.
[0127]
Here, the ground fault detected by the ground fault detecting device 100 disposed on the lead line L1-4 is generated on the load side of the mounting position of the present detecting device.
[0128]
On the other hand, when a ground fault occurs on the power supply side from the mounting position of the ground fault detection device 100, the circuit configuration in which the lead L1-4 and the ground fault detection circuit 100 are combined is shown in FIG. Can be represented by the following circuit diagram.
[0129]
In the circuit shown in FIG. 14A, the current I driven to the lead lines L1-4 by the signal voltage E is₀Is the charging current I with respect to the ground capacitance C4._COnly.
[0130]
FIG. 14B shows the current I₀FIG. 5 is a vector display. As is clear from the figure, since the effective component flowing through the ground fault resistance is zero, it can be determined that there is no fault location on the load side of the ground fault detection device 100.
[0131]
As described above, according to the second embodiment, the ground fault detection device is installed on the lead wire of the power line, so that the ground fault is located on either the load side or the power supply side with respect to the mounting position of the detection device. It is possible to determine whether there is a failure location, and it is possible to specify a location where a ground fault has occurred.
[0132]
[Embodiment 3]
As described above, in the first and second embodiments, the case where the ground fault detecting device according to the present invention is used for detecting a ground fault in a single-phase three-wire electric line is described as an example. The ground fault detection device according to the present invention is not limited to a single-phase three-wire system, but is a power line for supplying power from a low-voltage side of a transformer to a load. It is clear that the method is applicable regardless of the type of the grounding work. Specifically, a ground fault in a three-phase three-wire system or a three-phase four-wire system can be detected.
[0133]
Therefore, in the present embodiment, a case will be described in which the ground fault detection device of FIG. 1 is installed in a three-phase three-wire electric line to detect a ground fault.
[0134]
FIG. 15 is a circuit diagram of the three-phase three-wire electric line 300.
Referring to FIG. 15, three-phase three-wire electric line 300 includes three phases of a phase, b phase, and c phase, and has a line current I_a, I_b, I_cFlows each. The neutral point is the ground line L_EGrounded.
[0135]
Here, as shown in FIG. 15, a one-wire ground fault occurs, and the_fSuppose you have a ground fault.
[0136]
In the case of one-line ground fault, the voltage of phase a is_aThen, the line current I_a, I_b, I_cThe relations of equations (6) and (7) are established between.
[0137]
(Equation 6)

[0138]
(Equation 7)

[0139]
Zero phase current₀, And the positive-phase current₁, And the negative phase current₂Then, if the conditions of Expressions (6) and (7) are rewritten symmetrically, the relationship represented by Expression (8) is obtained.
[0140]
(Equation 8)

[0141]
Therefore, the voltage V of the a-phase_aIs the a-phase electromotive voltage E_a, The symmetrical component voltage V₀, V₁, V₂, Symmetrical impedance Z₀, Z₁, Z₂Using equation (6), equation (9) is given.
[0142]
(Equation 9)

[0143]
Further, when Expression (8) is substituted into Expression (9), Expression (10) is obtained.
[0144]
(Equation 10)

[0145]
Here, (Z₁+ Z₂) ≪ (Z₀+ 3Z_f), The zero-phase current I₀Is given by equation (11).
[0146]
(Equation 11)

[0147]
In the case of a ground fault on the low voltage side, the impedance Z_fIs considered to be only a resistance component, the three-phase three-wire electric line 300 in FIG. 15 can be represented by a zero-phase equivalent circuit in FIG.
[0148]
FIG. 16A is a zero-phase equivalent circuit of the three-phase three-wire electric line 300 in FIG. The present device is for detecting a micro-ground fault, in which case,₀≪Z_fTherefore, the zero-phase current I₀Is vector-displayed as shown in FIG.
[0149]
Referring to FIG. 16A, zero-phase current I₀Is the ground fault resistance Z_fCurrent I flowing through_ZAnd the charging current I of the ground capacitance C_CAnd the combined current. As shown in FIG. 16B, the zero-phase current I₀Is affected by the ground capacitance C.
[0150]
Therefore, similarly to the first embodiment, the zero-phase current I₀And the signal voltage E_aBy controlling the resistance value of the compensating resistor r inside the detection circuit 20 so that the phase difference between the two becomes zero, the influence of the ground capacitance C can be compensated. Therefore, also in the present embodiment, a ground fault can be detected by extracting only the ground fault current.
[0151]
As described above, according to the third embodiment of the present invention, the resistance value of the compensation resistor of the ground fault detection device is controlled such that the phase difference between the zero-phase current and the signal voltage becomes “0”. This makes it possible to compensate for the influence of the ground capacitance and detect a ground fault occurring in the three-phase three-wire system.
[0152]
As in the first embodiment, since the resistance obtained from the ground fault current after compensation corresponds to the ground fault resistance or the insulation resistance, a ground fault having both the ground fault detection and the insulation resistance measurement function is provided. A detection device is realized.
[0153]
[Embodiment 4]
Lastly, a remote monitoring system using the ground fault detection device according to the present invention will be described.
[0154]
FIG. 17 shows a configuration of a ground fault remote monitoring system according to the fourth embodiment of the present invention.
[0155]
The remote monitoring system according to the present embodiment includes a ground fault detecting device according to the present invention in a power receiving facility 400 for supplying power to a load facility owned by each customer, and a remote monitoring center 410 It is intended to remotely detect a ground fault.
[0156]
Referring to FIG. 17, in a power receiving facility 400 of a plurality of consumers, a neutral point of the type B ground is applied to a neutral point of the low-voltage side electric line 200 of the transformer T. Ground line L of each transformer T_EIs provided with the ground fault detection device 100 of FIG.
[0157]
The distribution system in each customer premises used in the remote monitoring system according to the present embodiment is an example of a standard distribution system.
[0158]
As shown in FIG. 17, as a power distribution system, a circuit breaker PAS that cuts off when a distribution line fails as a protection against overcurrent is provided on a distribution line that supplies power from a substation (not shown). The circuit breaker PAS is opened by a combination of the internal zero-phase current transformer ZCT and the relay G in order to prevent the influence on other customers when a ground fault occurs.
[0159]
Power via the circuit breaker PAS is driven to the instrument transformer PCT via the cable CVT. The instrument transformer PCT includes an instrument transformer PT for measuring an AC high voltage, and an instrument current transformer CT for measuring a large AC current. In the instrument transformer PCT, the AC high voltage (6600 V) is dropped to a low voltage (200 V) as a secondary voltage.
[0160]
Further, a load switch LBS is connected to the distribution line. The load switch LBS is used for disconnecting the transformer from the distribution line at the time of maintenance and inspection of the transformer or at the time of an accident.
[0161]
The distribution line is branched into a plurality of distribution lines and drives a high voltage to the primary side of each transformer T. A power fuse PF is coupled to the primary side of the transformer T, and cuts off a short-circuit current when the transformer T is internally short-circuited. Note that a power capacitor SC is coupled to the distribution line. The power capacitor SC is used for advancing a delay power factor caused by an inductive load, improving a power factor of a transmission and distribution line, and reducing power loss.
[0162]
In each transformer T, when the high voltage (6600V) on the primary side is transformed into a distribution voltage of 100-200V on the secondary side, it is transmitted to a plurality of loads via the distribution circuit breaker MCB. As described above, the secondary side of the transformer T is constituted by a single-phase three-wire system or a three-phase three-wire system, and the neutral point is a ground line L._EGrounded.
[0163]
Further, a ground fault detecting device according to the present invention is installed on the ground wire.
In the above configuration, when a low-frequency signal voltage E is applied from a power supply circuit (not shown) inside the ground fault detection circuit 100, the ground line L_E, A ground fault current is induced. The ground fault current is detected by the current transformer CT2 and driven to a detection circuit (not shown).
[0164]
The ground fault detection device 100 is connected to each ground line L_EThe ground fault current that flows through is constantly monitored. In the detection device, a current value serving as a reference for a ground fault is set in advance. The ground fault detection device 100 constantly compares the ground fault current after compensation for the influence of the ground capacitance with the set value. When the ground fault current reaches the set value, the ground fault detection circuit 100 detects the electric line on which the ground fault has occurred, and outputs a detection signal.
[0165]
Upon receiving the detection signal, the signal transmission device 110 issues an alarm to the monitoring center 410 via the communication line, and displays the customer name of the customer and the details of the failure on the screen of the monitoring center 410.
[0166]
The monitoring center 410 automatically notifies the portable terminal of the maintenance staff 420 of the details of the failure and informs them.
[0167]
As described above, according to the fourth embodiment of the present invention, by installing the ground fault detecting device on the low-voltage line in the power receiving facility premises of each customer, a ground that can be generated in the power receiving facility of each customer is provided. It is possible to construct a remote monitoring system capable of constantly monitoring a fault.
[0168]
The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0169]
【The invention's effect】
As described above, according to one aspect of the present invention, the combined current of the ground fault current and the charging current with respect to the ground capacitance is supplied to the detection circuit on the secondary side of the current transformer arranged on the ground line of the power line. By inducing and controlling the resistance value of the compensation resistor inside the detection circuit so that the phase difference between the combined current and the power supply voltage becomes “0”, it is possible to compensate for the influence of the ground capacitance. .
[0170]
Furthermore, since the resistance obtained from the compensated ground fault current corresponds to the ground fault resistance or the insulation resistance, a ground fault detection device having a ground fault detection and an insulation resistance measurement function is realized.
[0171]
In addition, a remote monitoring system capable of constantly monitoring a ground fault that may occur in a power receiving facility of each customer by constructing a ground fault detecting device on a low-voltage line in the power receiving facility premises of each customer is constructed. be able to.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a ground fault detection device according to a first embodiment of the present invention.
FIG. 2 shows a ground line L_EGround current I flowing back to₀FIG. 5 is a vector display.
FIG. 3 is a diagram illustrating an example of a circuit configuration of a phase difference detection unit 2 and a control unit 3 in FIG.
FIG. 4 is a zero-phase circuit diagram when the ground fault detecting device 100 of FIG. 1 and a single-phase three-wire electric line 200 are integrated.
FIG. 5 is a zero-phase equivalent circuit diagram according to the combination of the single-phase three-wire electric line 200 and the power supply circuit 10 of FIG.
6 is a simplified zero-phase equivalent circuit diagram obtained by simplifying the zero-phase equivalent circuit diagram of FIG. 5;
FIG. 7 is a simplified equivalent circuit diagram in which the detection circuit 20 of the ground fault detection apparatus 100 and a single-phase three-wire electric line are combined.
FIG. 8 illustrates a signal line E and a ground line L according to the signal voltage E;_EGround fault current I driven₀FIG. 4 is a diagram illustrating the dependence of the phase difference between the ground capacitance and the ground capacitance.
FIG. 9 shows a current i flowing through a compensation resistor r._rFIG. 5 is a diagram showing the dependence of the capacitance on the ground.
FIG. 10 shows a current i flowing through a compensation resistor r._rFIG. 9 is a diagram showing the result of compensating for the influence of the ground capacitance from FIG.
FIG. 11: Ground fault current I₀And current i flowing through compensation resistor r_rFIG. 6 is a diagram showing a relationship between the ground fault resistance R and a resistance value of the compensation resistor r and the ground fault resistance R.
FIG. 12 is a diagram showing a configuration example of a ground fault detection device according to a second embodiment of the present invention.
FIG. 13 shows a circuit configuration (FIG. 13 (a)) obtained by combining a lead line L1-4 and a ground fault detection circuit 100, and a ground fault current I flowing through the lead line L1-4.₀(FIG. 13 (b)).
FIG. 14 is a circuit configuration (FIG. 14A) in which a lead line L1-4 and a ground fault detection circuit 100 are combined, and a current I flowing through the lead line L1-4.₀(FIG. 14 (b)).
FIG. 15 is a circuit diagram of a three-phase three-wire electric line 300;
FIG. 16 is a zero-phase equivalent circuit diagram (FIG. 16A) of the three-phase three-wire electric line 300 shown in FIG.₀(FIG. 16 (b)).
FIG. 17 is a diagram showing a configuration of a ground fault fault remote monitoring system according to a fourth embodiment of the present invention.
FIG. 18 is a schematic block diagram showing a configuration of an example of a conventional insulation resistance measuring device described in Patent Document 1.
[Explanation of symbols]
1 power supply, 2 phase difference detection section, 3 control section, 4 ammeter, 5 relay circuit, 10 power supply circuit, 20 detection circuit, L_E  Ground wire, L1, L2 electric wire path, R ground fault resistance, C1, C2, C capacitance to ground, T, OT transformer, CT1, CT2 current transformer, M servo motor, r compensation resistor, q compensation capacitor , OP1 to OP5 Operational amplifier, R1 to R14 resistor, PAS circuit breaker, G relay, CVT cable, PCT instrument transformer, LBS load switch, PF power fuse, SC power capacitor, MCB power distribution circuit breaker, ZCT Zero-phase current transformer, AMP amplifier, FIL filter circuit, DET rectifier circuit, OSC oscillator, L_P  Loop ground wire, 100 ground fault detection circuit, 110 signal transmission device, 200 single-phase three-wire system, 300 three-phase three-wire system, 400 power receiving equipment, 410 monitoring center, 420 maintenance personnel.

Claims (6)

A ground fault detector for detecting a ground fault generated in a low-voltage line,
A power supply circuit for applying a signal voltage of a frequency lower than a commercial frequency to a ground line arranged at a neutral point of the transformer of the low-voltage line,
A detection circuit that detects a ground fault based on a ground fault current returned from the low-voltage line to the ground line in accordance with the signal voltage,
The detection circuit,
A current transformer that is arranged on the ground line and induces the ground fault current inside the detection circuit; and a resistance element and a capacitance element connected in parallel, and are driven by the resistance element by being induced from the current transformer. A compensating circuit for compensating for the ineffective component of the ground fault current,
A phase difference detection unit that detects a phase difference between the ground fault current and the signal voltage driven by the resistance element, and outputs a detection result signal;
A value of the resistance element and the capacitance element of the compensation circuit is controlled based on a detection result signal of the phase difference detection unit, and a position of the ground fault current and the signal voltage driven by the resistance element is controlled. A control unit that controls the phase difference to be zero,
A ground fault detecting unit that constantly monitors the current value of the ground fault current driven by the resistance element whose ineffective component is compensated, detects a ground fault when a predetermined current value is exceeded, and issues an alarm. A ground fault detection device comprising: The control unit controls one or both of a resistance value of the resistance element and a capacitance value of the capacitance element of the compensation circuit based on a detection result signal of the phase difference detection unit. 2. The ground fault detection device according to 1. The ground fault detection unit includes a resistance measuring unit that measures a ground fault resistance or an insulation resistance of the low piezoelectric line based on a current value of the ground fault current driven by the resistance element whose ineffective component has been compensated. The ground fault detection device according to claim 1, further comprising: Ground fault detection means for detecting a ground fault occurring in the low-voltage line, and detecting a ground fault in the low-voltage line, a plurality of lead lines connecting a branch point of the low-voltage line and each load. Disposed, detecting a ground fault occurring in each of the plurality of lead wires, and comprising a ground fault location detecting means for identifying a ground fault location from the detection result,
The ground fault detection means,
A first power supply circuit for applying a signal voltage of a frequency lower than a commercial frequency to a ground line disposed at a neutral point of the transformer of the low-voltage line,
A first detection circuit that detects a ground fault based on a ground fault current returned from the low-voltage line to the ground line in accordance with the signal voltage,
The ground fault location detection means,
A second power supply circuit for applying a signal voltage having a frequency lower than a commercial voltage to the lead wire;
A second detection circuit that detects a ground fault based on a ground fault current returned from the ground to the lead line in accordance with the signal voltage,
The first and second detection circuits include:
A current transformer arranged on the ground wire and the lead wire, respectively, for inducing the ground fault current inside the detection circuit;
Including a resistance element and a capacitance element connected in parallel, a compensation circuit for compensating for the ineffective component of the ground fault current induced from the current transformer and driven by the resistance element,
A phase difference detection unit that detects a phase difference between the ground fault current and the signal voltage driven by the resistance element, and outputs a detection result signal;
A value of the resistance element and the capacitance element of the compensation circuit is controlled based on a detection result signal of the phase difference detection unit, and a position of the ground fault current and the signal voltage driven by the resistance element is controlled. A control unit that controls the phase difference to be zero,
A ground fault detecting unit that constantly monitors the current value of the ground fault current driven by the resistance element whose ineffective component is compensated, detects a ground fault when a predetermined current value is exceeded, and issues an alarm. A ground fault detection device comprising: The control unit controls one or both of a resistance value of the resistance element and a capacitance value of the capacitance element of the compensation circuit based on a detection result signal of the phase difference detection unit. 5. The ground fault detection device according to 4. A ground fault remote management system for remotely monitoring and detecting a ground fault occurring in the power receiving equipment of each of the plurality of customers,
A ground fault detector that is grounded to the neutral point of the transformer of the low-voltage line in the power receiving facility premises of each of the plurality of consumers;
A signal transmission device that transmits an alarm that the ground fault detection device detects and issues a ground fault,
It is located remotely from the power receiving equipment of each of the plurality of customers, constantly monitors an alarm transmitted from the signal transmission device of each of the plurality of customers, and performs maintenance on the power receiving equipment of the customer where the alarm is detected. With a monitoring center to dispatch personnel,
The ground fault detection device,
A power supply circuit that applies a signal voltage of a frequency lower than the commercial frequency to a ground line disposed at a neutral point of the transformer of the low-voltage line in the power receiving facility premises of each of the plurality of consumers,
A detection circuit that detects a ground fault based on a ground fault current returned from the electric line to the ground line in accordance with the signal voltage,
The detection circuit,
A current transformer that is arranged on the ground line and induces the ground fault current inside the detection circuit; and a resistance element and a capacitance element connected in parallel, and are driven by the resistance element by being induced from the current transformer. A compensating circuit for compensating for the ineffective component of the ground fault current,
A phase difference detection unit that detects a phase difference between the ground fault current and the signal voltage driven by the resistance element, and outputs a detection result signal;
A value of the resistance element and the capacitance element of the compensation circuit is controlled based on a detection result signal of the phase difference detection unit, and a position of the ground fault current and the signal voltage driven by the resistance element is controlled. A control unit that controls the phase difference to be zero,
A ground fault detecting unit that constantly monitors the current value of the ground fault current driven by the resistance element whose ineffective component is compensated, detects a ground fault when a predetermined current value is exceeded, and issues an alarm. And a ground fault remote monitoring system.

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