JP2004297967A

JP2004297967A - Protection relay system

Info

Publication number: JP2004297967A
Application number: JP2003089729A
Authority: JP
Inventors: Yoshinori Hirata; 善則平田; Takanari Kita; 隆成北; Naoto Inaba; 直人因幡; Masao Hori; 政夫堀; Masato Okazaki; 正人岡崎; Hiroshi Nishida; 宏西田
Original assignee: Chugoku Electric Power Co Inc; TMT & D KK; TD System Technology Corp
Current assignee: Chugoku Electric Power Co Inc; TMT & D KK; TD System Technology Corp
Priority date: 2003-03-28
Filing date: 2003-03-28
Publication date: 2004-10-21
Anticipated expiration: 2023-03-28
Also published as: JP3940691B2

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of the conventional sequential shield function method that, since the order of shielding is decided in advance, shielding of lines other than an accident line is highly possible, resulting in taking much time in removing the accident. <P>SOLUTION: The current of a line connected to a bus line of a high resistance ground grid is detected, and the line with high possibility of accident is preferentially selected and shielded while an accident continues. Thus, the duration time of accident is shortened and the power outage range is narrowed for easy restoration of the grid. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、電力系統の事故継続を検出して、所定時間以内に事故除去を行うための保護継電装置に関する。
【０００２】
【従来の技術】
従来、高抵抗接地系統の事故が長時間に亘って継続した場合、中性点抵抗器（以下、ＮＧＲと呼ぶ）の耐量を超えないように、１線地絡の事故継続状況を検出して、母線に接続されている回線を、予め決められた順序に従って順次遮断していくという方式（順序遮断機能）が取られている（例えば、非特許文献１参照。）。
ここでは、その一例として、以下に、具体的な事例について図を用いて説明する。
【０００３】
図１０は、従来の保護継電装置の構成図である。同図において、２０１は変圧器バンクであり、複数の変圧器バンク２０１が複母線甲・乙に接続されている。図には示していないが、変圧器バンク２０１の上位系が電源である。２０２は母線に接続されている送電線で、２０３，２０４，２０５は遮断器である。
【０００４】
２０６は保護継電装置であり、変圧器バンク２０１の電流および変圧器中性点に設置されているＮＧＲの電流と母線の電圧を入力として事故検出と事故継続時の遮断判定を行う機能を持っている。すなわち、地絡事故が発生した場合は、母線の零相電圧と変圧器中性点に設置されているＮＧＲの電流を検出し、送電線の保護装置と協調を取った所定時間後に、予め決められた遮断順序と時限に従って回線を１回線ずつ遮断していく。
【０００５】
図１１は、地絡事故の場合のアルゴリズムを示すフローチャート例を示す。同図において、ステップ２１１、ステップ２１２では、常時入力された電圧・電流を演算し事故検出を行っている。事故が検出されると、ステップ２１３では、送電線回路保護装置と協調を取った所定の時間Ｔ０１が経過した後であれば、本順序遮断機能方式が起動されて、ステップ２１４では、１番初めに遮断するように設定された＃１Ｌ回線が遮断される。その後、ステップ２１５では、事故除去が行われたかを確認し、事故が継続している場合は、ステップ２１６で、Ｔ０２時限後に２番目に設定された＃２Ｌ回線が遮断される。
【０００６】
このように、予め指定された遮断順序に従って回線を遮断していく。なお、時限Ｔ０１は０．５ｓｅｃ、時限Ｔ０２は１．０ｓｅｃ、さらに、Ｔ０３は１．５ｓｅｃというオーダーである。
【０００７】
【非特許文献１】
後備保護継電方式専門委員会著「後備保護継電方式」電気協同研究３７巻１号、１９８１年６月、ｐ．２０−２１
【０００８】
【発明が解決しようとする課題】
このように、従来の順序遮断機能方式では、予め遮断順序を決めているため、事故回線以外の遮断が行われる可能性が大きく、そのため、事故除去時間も遅くなるという問題があった。
【０００９】
したがって、本発明は、高抵抗接地系統の母線に接続される回線の電流を検出し、事故が継続している時に事故と思われる回線を優先的に選択して遮断することにより、事故継続時間を短縮するとともに、停電範囲を狭くして系統の復旧を容易にする保護継電装置を提供することを目的とする。
【００１０】
【課題を解決するための手段】
上記の目的を達成するために、請求項１に記載の保護継電装置は、高抵抗接地系統の母線に接続される各回線の電気量を入力し、該電気量を演算し、演算結果に基いて所定の回線を予め定められた順序に従って遮断する保護継電装置において、地絡事故継続を検出する地絡事故検出手段と、各回線の零相電流から有効分電流を検出する零相電流検出手段と、地絡事故検出手段の出力信号によって、零相電流検出手段で検出された有効分電流の最も大きい回線に遮断指令を出し、所定の時間後に地絡事故検出手段の出力信号が継続していれば、上記操作を繰返す遮断回線選択手段とを備えたことを特徴とする。
これにより、高抵抗接地系統の母線に接続される回線の零相有効分電流を検出し、事故が継続している時に事故の可能性の高い回線を優先的に選択して遮断することができるので、事故継続時間を短縮することができる。
【００１１】
請求項２に記載の保護継電装置は、高抵抗接地系統の母線に接続される各回線の電気量を入力し、該電気量を演算し、演算結果に基いて所定の回線を予め定められた順序に従って遮断する保護継電装置において、地絡事故継続を検出する地絡事故検出手段と、各回線の零相電流から有効分電流を検出する零相電流検出手段と、地絡事故検出手段の出力信号によって、零相電流検出手段で検出された有効分電流の最も大きい回線に遮断指令を出し、所定の時間後に地絡事故検出手段の出力信号が継続していれば、上記操作を繰返す遮断回線選択手段と、母線に接続される変圧器バンク回線方向の事故を判定する変圧器バンク回線事故判定手段と、地絡事故検出手段の出力と変圧器バンク回線方向事故判定手段の出力信号が同時に出力された時は、所定の時間後に優先的に変圧器バンク回線に遮断指令を出力する変圧器バンク回線遮断手段とを備えたことを特徴とする。
これにより、変圧器バンク回線に事故方向を識別する機能をもたせ、事故継続を検出した時に、変圧器バンク方向に事故がある場合には、最初に変圧器バンクの遮断器（ＣＢ）を遮断することになる。従来の保護装置では、送電線回線を遮断した後に変圧器バンク回線を遮断するというシーケンスであるために、変圧器バンク回線の事故の場合に事故遮断まで極めて時間を要していた点を改善することができる。
【００１２】
請求項３記載の保護継電装置は、高抵抗接地系統の母線に接続される各回線の電気量を入力し、該電気量を演算し、演算器に基いて所定の回線を予め定められた順序に従って遮断する保護継電装置において、地絡事故継続を検出する地絡事故検出手段と、各回線の零相電流から有効分電流を複数段の検出レベルを持つ有効分電流検出要素で検出するレベル別零相電流演算手段と、地絡事故検出手段の出力信号が出力されている期間に零相有効分電流演算手段で検出された各回線の有効分電流を該電流の検出レベルと比較して、各回線のうち最大検出レベルで動作している回線に遮断指令を出力し、前記地絡事故検出手段の出力信号が継続していれば、所定の時間間隔で上記操作を繰返すレベル別遮断回線選択手段とを備えた事を特徴とする。
これにより、高抵抗接地系統の母線に接続される回線の零相有効分電流を検出し、事故が継続している時に事故の可能性が高い回線を優先的に選択して遮断することができる。
【００１３】
請求項４記載の保護継電装置は、高抵抗接地系統の母線に接続される各回線の電気量を入力し、該電気量を演算し、演算結果に基いて所定の回線を予め定められた順序に従って遮断する保護継電装置において、地絡事故継続を検出する地絡事故検出手段と、各回線の零相電流から有効分電流を検出する零相電流演算手段と、母線に接続される変圧器バンク回線の零相有効分電流の合計電流を求める零相有効分電流合計演算手段と、零相有効分電流合計演算手段で得られた合計電流に１より小さい係数Ｋを掛け合せた値以上の零相有効分電流が流れる回線を優先的に選択する回線選択手段と、地絡事故検出手段の出力信号が出力されている期間に前記回線選択手段で検出された回線に遮断指令を出力し、前記地絡事故検出手段の出力信号が継続していれば、所定の時間間隔で上記操作を繰返す回線遮断手段とを備えたことを特徴とする。
これにより、高抵抗接地系統の地絡事故時に事故が継続している場合に、複数の変圧器バンク回線の零相有効分電流の合計（Ｉ_０ＢＴ）を演算し、各回線の零相有効分電流（Ｉ_ＯＲ）がこの値（Ｉ_０ＢＴ）のＫ倍（但しＫは０＜Ｋ＜１）以上の回線を選択して遮断し、事故が継続している時に事故の可能性の高い回線を優先的に選択して遮断するので、事故継続時間を短縮することができる。
【００１４】
請求項５記載の保護継電装置は、高抵抗接地系統の母線に接続される各回線の電気量を入力し、該電気量を演算し、演算結果に基いて所定の回線を予め定められた順序に従って遮断する保護継電装置において、地絡事故継続を検出する地絡事故検出手段と、各回線の零相電流から有効分電流を検出する零相有効分電流演算手段と、母線に接続される変圧器バンク回線の中性点に設置された中性点抵抗器に流れる電流を検出し合計演算を行うＮＧＲ中性点合計電流演算手段と、ＮＧＲ中性点合計電流演算手段で得られた電流値に１より小さい係数Ｋを掛け合せた値以上の電流値の回線を優先的に選択する回線選択手段と、地絡事故検出手段の出力信号が出力されている期間に回線選択手段で検出された回線に遮断指令を出力し、地絡事故検出手段の出力信号が継続していれば、所定の時間間隔で上記操作を繰返す回線遮断手段とを備えたことを特徴とする。
これにより、高抵抗接地系統の地絡事故時に事故が継続している場合、複数の変圧器の中性点に設置されている中性点抵抗器（ＮＧＲ）を流れる電流の合計値（Ｉ_ＮＲＴ）を求めて、各回線の零相有効分電流（Ｉ_ＯＲ）が、この値のＫ倍（但しＫは０＜Ｋ＜１）以上の回線を選択して遮断することにより、事故が継続している時に事故の可能性の高い回線を優先的に選択して遮断するので、事故継続時間を短縮することができる。
【００１５】
請求項６記載の保護継電装置は、高抵抗接地系統の母線に接続される各回線の電気量を入力し、該電気量を演算し、演算結果に基いて所定の回線を予め定められた順序に従って遮断する保護継電装置において、地絡事故継続を検出する地絡事故検出手段と、各回線の零相電流から有効分電流を検出する零相有効分電流演算手段と、回線が平行回線の場合、２回線合計の零相有効分電流を求める２回線合計零相有効分電流演算手段と、地絡事故検出手段の出力信号が出力されている期間に、零相有効分電流演算手段と２回線合計零相有効分電流演算手段とで検出された零相有効分電流のうち、最大回線を選択し、その最大回線が平行回線ではない場合は、その回線を選択し、その最大回線が平行回線の場合は、その２回線のうち、零相有効分電流の大きい方の回線に遮断指令を出力し、地絡事故検出手段の出力信号が継続していれば、所定の時間間隔で上記操作を繰返す回線遮断手段とを備えたことを特徴とする。
これにより、高抵抗接地系統の地絡事故時に事故が継続している場合で、しかも、平行２回線系統で零相循環電流が流れている場合に、平行２回線の合計零相有効分電流（Ｉ_０ＲＴ）を演算し、各回線電流の零相有効分電流（Ｉ_０Ｒ）と平行２回線の合計零相有効分電流（Ｉ_０ＲＴ）のうち最大回線を選択し、その最大回線が１回線系統であれば、その回線を遮断することにより、事故除去時間を早くすることができる。
【００１６】
【発明の実施の形態】
（第１の実施の形態：請求項１に対応）
図１は、本実施の形態を実現するための保護システムの構成図であり、１１が本発明の保護継電装置である。また、図２は、この保護継電装置をディジタルリレーで実現したハードウェア構成図である。
【００１７】
図１では、送電線回線あるいは変圧器バンク回線１が、母線３または４に接続されている。母線３，４は、母線連絡線５で繋がれており、各回線および母線連絡線５には、それぞれに遮断器２および電流変成器６（以下ＣＴと称す）が設置されている。また、母線３，４には、電圧変成器（以下ＰＴと称す）７甲、７乙が設置されている。これらの各ＣＴと各ＰＴからの信号が保護継電装置１１に入力される。
【００１８】
保護継電装置１１には、地絡事故検出手段１２、零相電流検出手段１３、遮断回線選択手段１４が設置されており、回線単位の遮断出力が可能なように構成されている。
【００１９】
図２は、保護継電装置１１が、ディジタルリレーで構成されている図である。各ＣＴ，ＰＴの入力変換器１１１、アナログフィルター（ＡＦ）１１２、アナログディジタル変換器（ＡＤＣ）１１３、前置プロセッサ（ＦＥＰ）１１４、中央演算処理装置（ＣＰＵ）１１５、プログラムを収納するメモリー（ＲＯＭ）１１６、ＣＰＵで判断された結果を出力する入出力インターフェース（Ｉ／Ｏ）１１７、および本装置から各回線遮断指令を出力する出力回路１１８によって構成されている。
【００２０】
図３は、図２の構成に示しているディタルリレーのソフトウェアのアルゴリズムのフローチャートである。
【００２１】
ステップ２１では、各回線のＣＴ二次電流から零相電流が、またＰＴ二次電圧あるいは三次電圧から母線電圧が入力され、常時演算されている。ステップ２２では、系統に事故が発生したか否かを監視し、事故発生は、母線電圧の低下、あるいは零相電圧の有無で検出する。ステップ２３では、事故が所定時間（Ｔ１）継続しているか否かを判断する。一般に電力系統の保護システムには、保護区間が限定されていて、高速に検出遮断する装置（以下主保護装置と称する）があるが、このＴ１は、この主保護装置による事故除去までの時間に尤度を持って確認するための時間である。所定時間（Ｔ１）以上事故が継続している場合には、主保護装置によって事故が除去されなかったものとみなし、本発明の保護継電装置１１の機能が起動して、後備保護的な処置をすることになる。
【００２２】
ステップ２４では、各回線の零相電流から、その有効分電流を求める。電力系統には、ケーブル系統もあるので、線路のキャパシタンスが大きい場合には、進み電流を補償するために変圧器の中性点にリアクトルを設置して進み電流を補償する形態が多く取られている。このため、各回線に流れる電流は、事故回線以外の回線が、そのようなキャパシタンスやリアクタンスの電流で大きくなり、事故回線と見誤ってしまう。これを防ぐためには、中性点接地抵抗器（ＮＧＲ）の電流と同相の電流を得ればよく、そのために、零相電流の有効分を求めることにした。零相電流の有効分は、事故時に母線電圧から得られる零相電圧または各相電圧の位相を基準として求めるもので、従来の保護リレーなどで採用されている手法と同じく容易に求めることができるものである。
【００２３】
ステップ２５では、この演算された零相有効分電流が最大の回線を選択して遮断する。ステップ２５で、零相有効分電流の最大回線が選択遮断された後、ステップ２６では、事故が除去されたかどうかを判断し、事故が除去されている場合には、本アルゴリズム機能が終了する。
【００２４】
事故が除去されていない場合は、ステップ２７で、所定時間（Ｔ２）後に、再度残った回線から、零相有効分電流の最大回線を選択して遮断する。このＴ２は、装置の遮断出力から事故除去までに要する時間に尤度をもって確認するための時間である。このステップを事故除去が行われるまで繰り返す。なお、フローチャートの各ステップ順序は一例であり、本発明の趣旨が変わらない限り変更してもよい。
【００２５】
本実施の形態によれば、高抵抗接地系統の母線に接続される回線の零相有効分電流を検出し、事故が継続している時に事故と思われる回線を優先的に選択して遮断することにより、事故継続時間を短縮することができる。
【００２６】
（第２の実施の形態：請求項２に対応）
図４は、第２の実施の形態のアルゴリズムを示すフローチャートである。同図は、変圧器バンク回線に事故方向を識別する機能をもたせ、高抵抗接地系統の地絡事故時に、変圧器バンク回線方向に事故がある場合には、最初に変圧器バンク回線の遮断器（ＣＢ）を遮断する方法である。
【００２７】
本実施の形態では、中性点に中性点接地抵抗（ＮＧＲ）を設置している変圧器バンク側の地絡事故を検出した場合は、送電線回線の零相有効分電流の大きさに関わらず、変圧器バンクを遮断して、その後、なお事故継続している場合は、送電線回線の零相有効分電流の最大回線を選択して遮断するシーケンスを採っている。
【００２８】
図４において、ステップ３１からステップ３３までは、実施の形態１における図３と同じフローチャートである。ステップ３４では、変圧器バンク回線側に事故があるか否かを判定し、事故が変圧器バンク回線側であれば、ステップ３５で、変圧器の一次、二次遮断器（ＣＢ）を遮断し、ステップ３６で、なお事故継続であるか否かを判定する。
【００２９】
変圧器バンク回線方向の事故でなければ、ステップ３７で、各回線の零相有効分電流を演算し、ステップ３８で、その最大回線を選択し遮断する。その後、事故除去したかどうかをステップ３６で判定し、事故除去でなければ、所定時間（Ｔ２）後に、さらに各回線の零相有効分電流の最大回線を選択し遮断する。このように事故除去が確認できるまで繰り返す。
【００３０】
本実施の形態によれば、変圧器バンク回線方向の事故を識別する機能をもたせ、事故継続を検出した時に、変圧器バンク方向に事故がある場合には、優先的に変圧器バンク回線の遮断器（ＣＢ）を遮断するので、従来の保護装置では、送電線回線を遮断した後に変圧器バンク回線を遮断するというシーケンスであるために、事故遮断まで極めて時間を要していた点を改善することができる。
【００３１】
（第３の実施の形態：請求項３に対応）
図５は、第３の実施の形態に使用する複数段の零相有効分電流を検出するレベルの識別要素を示している。同図の複数段の検出レベルの識別要素は、以下のとおりに定める。
【００３２】
事故検出電流最小レベルとしては、ＳＮ比を考慮して、中性点抵抗器（ＮＧＲ）の最小電流の３０％以上を検出できればよい。また、事故検出電流最大レベルとしては、平行回線があると考えると、ＮＧＲの最大電流（１００％地絡時の電流）の１／２以上の電流が検出できればよい。したがって、回線の零相有効分電流検出レベルの識別要素は、ＮＧＲの最小電流のの０．３倍から、ＮＧＲの最大電流の１／２倍までを複数段で構成したものであればよい。
【００３３】
例えば、ＮＧＲ電流が１５０Ａ×３台で構成された系統の場合、検出レベルの識別要素の最小は１５０Ａの３０％で４５Ａであり、最大は４５０Ａの１／２の２２５Ａ以上の電流である。一方、平行２回線の場合には、２回線に分流するため、最大は２２５Ａ／２＝１１２．５Ａとなるので、この電流以上の電流が流れていれば、最大電流回線と判断することになる。
そこで、検出レベルの識別要素としては、４５Ａから２２５Ａの間を、ＮＧＲによる電流容量と平行２回線構成を考慮した検出感度として、２２５Ａ−１５０Ａ−１１２．５Ａ−７５Ａ−４５Ａ−２２．５Ａというように複数段の検出要素を設ける必要がある。
【００３４】
図６は、前述した複数段の零相有効分電流検出機能を持たせた第４の実施の形態におけるアルゴリズムを示すフローチャートである。同図において、ステップ４１から４４までは第１乃至第３の実施の形態と同様である。
【００３５】
ステップ４５では、複数段検出要素の最も感度の悪いレベルＬｎ（最大電流レベル）が動作している回線があるかどうかを判定し、あればその回線をステップ４８で遮断し、ステップ４９では、ステップ４８で遮断したことにより事故除去したかどうかを判定する。ステップ４５で、レベルＬｎを超えた回線が無い場合は、次のステップ４６で、レベルＬｎ−１で動作している回線を選択し、前述したと同様の判定処理を行う。これを繰り返して事故を除去する。
【００３６】
本実施の形態によれば、高抵抗接地系統の母線に接続される回線の零相有効分電流を検出し、回線の零相有効分電流検出要素を、ＮＧＲ電流の最小の０．３から、ＮＧＲ電流の最大の１／２までを複数段の検出要素で構成し、最悪レベル（最大電流）の事故回線を優先的に選択し、事故が継続している時に事故と思われる回線を優先的に選択して遮断することにより、事故継続時間を短縮することができる。
【００３７】
（第４の実施の形態：請求項４に対応）
図７は、第４の実施の形態におけるアルゴリズムのフローチャートを示したものである。同図は、高抵抗接地系統の地絡事故時に事故が継続している場合に、
複数の変圧器バンク回線の零相有効分電流の合計（Ｉ_０ＢＴ）を演算し、各回線の零相有効分電流（Ｉ_ＯＲ）が合計（Ｉ_０ＢＴ）を１より小さい計数Ｋを掛け合せた値以上の回線を選択して遮断し、事故除去を行うことを示している。ここで、例えばＫを１／２として、各回線の零相有効分電流の大きさＩ_ＯＲが合計（Ｉ_０ＢＴ）の１／２以上であれば、その回線は、事故回線であると判断できるものとする。
【００３８】
図７において、ステップ５１から５４は、第３の実施の形態を示す図３と同じフローチャートである。ステップ５５以降が、本実施の形態の特徴を示す。ステップ５５で、複数の変圧器バンク回線の零相有効分電流の合計（Ｉ_０ＢＴ）を演算し、ステップ５６で、各回線の零相有効分電流Ｉ_ＯＲとの比較を行い、Ｉ_０Ｒ＞Ｋ・Ｉ_０ＢＴ（ただし、０＜Ｋ＜１）の回線を選択して遮断する。ステップ５７で、事故を除去したかどうかを判定し、事故が除去できていない場合は、再度前述のフローを繰り返す。
【００３９】
本実施の形態によれば、高抵抗接地系統の地絡事故時に事故が継続している場合に、複数の変圧器バンク回線の零相有効分電流の合計（Ｉ_０ＢＴ）を演算し、各回線の零相有効分電流（Ｉ_ＯＲ）がこの値（Ｉ_０ＢＴ）のＫ倍（但し、Ｋは０＜Ｋ＜１）以上の回線を選択して遮断するので、事故が継続している時に事故と思われる回線を優先的に選択して遮断することにより、事故継続時間を短縮することができる。
【００４０】
（第５の実施の形態：請求項５に対応）
図８は、第５の実施の形態におけるアルゴリズムのフローチャートである。同図は、高抵抗接地系統の地絡事故時に事故が継続している場合、複数の変圧器の中性点に設置されている中性点抵抗器（ＮＧＲ）を流れる電流の合計値（Ｉ_ＮＲＴ）を求めて、各回線の零相有効分電流（Ｉ_ＯＲ）が、この値（Ｉ_ＮＲＴ）のＫ倍（但しＫは０＜Ｋ＜１）以上の回線を選択して遮断することを示している。
【００４１】
本実施の形態は、第４の実施の形態と同じ考え方であり、詳細の説明は省略する。
本実施の形態によれば、高抵抗接地系統の地絡事故時に事故が継続している場合、複数の変圧器の中性点に設置されている中性点抵抗器（ＮＧＲ）を流れる電流の合計値（Ｉ_ＮＲＴ）を求めて、各回線の零相有効分電流（Ｉ_ＯＲ）が、この値のＫ倍（但しＫは０＜Ｋ＜１）以上の回線を選択して遮断するので、事故が継続している時に事故と思われる回線を優先的に選択して遮断することにより、事故継続時間を短縮することができる。
【００４２】
（第６の実施の形態：請求項６に対応）
図９は、第６の実施の形態におけるアルゴリズムのフローチャートである。同図は、高抵抗接地系統の地絡事故時に事故が継続している場合で、しかも、平行２回線系統で零相循環電流が流れている場合の処置を示している。
【００４３】
ステップ７１から７４は、第１の実施の形態における図３と同じである。ステップ７５で、平行２回線の合計零相有効分電流（Ｉ_０ＲＴ）を演算し、ステップ７６で、各回線電流の零相有効分電流（Ｉ_０Ｒ）と平行２回線の合計零相有効分電流（Ｉ_０ＲＴ）のうち最大回線を選択し、ステップ７８で、その最大回線が１回線系統であれば、その回線を遮断する。
【００４４】
ステップ７９で、その最大回線が平行２回線系統であれば、その２回線のうち、Ｉ_０Ｒの大きい方の回線を選択して遮断する。遮断した結果、ステップ８０で、事故が除去されたかどうかを判定する。その結果、事故が除去されていれば、本機能動作は終了し、事故が除去されていなければ、Ｔ２時間後に、ステップ７４に戻り、同様の処理を繰返す。
【００４５】
本実施の形態によれば、高抵抗接地系統の地絡事故時に事故が継続している場合で、しかも、平行２回線系統で零相循環電流が流れている場合でも、事故回線を短時間で選択・遮断することにより、事故除去時間を短くすることができる。
【００４６】
【発明の効果】
以上のように、本発明によれば、事故継続時に事故電流の大きな回線から遮断することによって、事故除去時間を早くすることができ、また、中性点抵抗器（ＮＧＲ）などの中性点接地機器の電流耐量も少なくてすむという利点がある。
【図面の簡単な説明】
【図１】第１の実施の形態のシステム構成図である。
【図２】第１の実施の形態のシステム構成図をディジタルリレーで構成しなおした図である。
【図３】第１の実施の形態のアルゴリズムを示すフローチャートである。
【図４】第２の実施の形態のアルゴリズムを示すフローチャートである。
【図５】第３の実施の形態の複数段持った有効分電流検出要素を説明する図である。
【図６】第３の実施の形態のアルゴリズムを示すフローチャートである。
【図７】第４の実施の形態のアルゴリズムを示すフローチャートである。
【図８】第５の実施の形態のアルゴリズムを示すフローチャートである。
【図９】第５の実施の形態のアルゴリズムを示すフローチャートである。
【図１０】従来の保護継電装置の構成図である。
【図１１】従来の保護継電装置のアルゴリズムを示すフローチャートである。
【符号の説明】
１・・・送電線回線または変圧器バンク回線、２・・・遮断器、３，４・・・母線、５・・・母線連絡線、６・・・電流変成器、７甲，７乙・・・電圧変成器、１１・・・保護継電装置、１２・・・地絡事故検出手段、１３・・・零相電流検出手段、１４・・・遮断回路選択手段、１１１・・・ＣＴ，ＰＴの変換装置、１１２・・・アナログフィルター、１１３・・・アナログディジタル変換器、１１４・・・ＦＥＰ、１１５・・・ＣＰＵ、１１６・・・ＲＯＭ、１１７・・・Ｉ／Ｏ、１１８・・・各回線遮断命令、２０１・・・変圧器バンク、２０２・・・送電線、２０３，２０４，２０５・・・遮断器、２０６・・・送電線保護装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a protective relay device for detecting the continuation of an accident in a power system and removing the accident within a predetermined time.
[0002]
[Prior art]
Conventionally, when an accident of a high-resistance grounding system continues for a long time, a continuation of an accident due to a single-line ground fault is detected so as not to exceed a tolerance of a neutral point resistor (hereinafter, referred to as NGR). In addition, a system (sequence interruption function) is adopted in which lines connected to a bus are sequentially interrupted in a predetermined order (for example, see Non-Patent Document 1).
Here, as an example, a specific case will be described below with reference to the drawings.
[0003]
FIG. 10 is a configuration diagram of a conventional protection relay device. In the figure, reference numeral 201 denotes a transformer bank, and a plurality of transformer banks 201 are connected to a double bus A / B. Although not shown in the figure, the upper system of the transformer bank 201 is a power supply. 202 is a transmission line connected to the bus, and 203, 204 and 205 are circuit breakers.
[0004]
Reference numeral 206 denotes a protection relay, which has a function of detecting an accident and judging interruption when the accident continues by using the current of the transformer bank 201, the current of the NGR installed at the neutral point of the transformer and the voltage of the bus as inputs. ing. In other words, when a ground fault occurs, the zero-phase voltage of the bus and the current of the NGR installed at the neutral point of the transformer are detected, and a predetermined time is determined after coordination with the protection device of the transmission line. Lines are cut off line by line in accordance with the cutoff order and time limit.
[0005]
FIG. 11 shows an example of a flowchart illustrating an algorithm in the case of a ground fault. In FIG. 11, in steps 211 and 212, the input voltage / current is always calculated to detect an accident. When an accident is detected, in step 213, after a lapse of a predetermined time T01 in cooperation with the transmission line circuit protection device, the sequence cutoff function system is activated. The # 1L line set to be cut off is cut off. Then, in step 215, it is confirmed whether or not the accident has been eliminated. If the accident has continued, in step 216, the # 2L line set second after the T02 time limit is disconnected.
[0006]
In this way, the lines are cut off in accordance with the cutoff order specified in advance. Note that the time period T01 is on the order of 0.5 sec, the time period T02 is on the order of 1.0 sec, and the time period T03 is on the order of 1.5 sec.
[0007]
[Non-patent document 1]
"Protective protection relay method" Technical Committee, "Protective protection relay method", Electric Cooperative Research Vol. 37, No. 1, June 1981, p. 20-21
[0008]
[Problems to be solved by the invention]
As described above, in the conventional order cutoff function system, since the cutoff order is determined in advance, there is a high possibility that the line other than the faulty line will be cut off, and therefore, the time required for clearing the fault will be slow.
[0009]
Therefore, the present invention detects the current of the line connected to the bus of the high-resistance grounding system, and preferentially selects and shuts off the line considered to be an accident when the accident continues, thereby reducing the accident continuation time. It is an object of the present invention to provide a protective relay device that shortens a power failure range, narrows a power failure range, and facilitates restoration of a system.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a protection relay device according to claim 1 inputs an electric quantity of each line connected to a bus of a high-resistance grounding system, calculates the electric quantity, and calculates a calculation result. In a protective relay that cuts off a predetermined line based on a predetermined order, a ground fault detecting means for detecting a continuation of a ground fault, and a zero-phase current for detecting an effective component current from a zero-phase current of each line. Based on the output signal of the detection means and the ground fault detection means, a cutoff command is issued to the line having the largest effective component current detected by the zero-phase current detection means, and the output signal of the ground fault detection means continues after a predetermined time. And a cutoff line selecting means for repeating the above operation.
As a result, the zero-phase effective component current of the line connected to the bus of the high-resistance grounding system can be detected, and a line with a high possibility of an accident can be preferentially selected and interrupted when the accident continues. Therefore, the duration of the accident can be reduced.
[0011]
The protection relay device according to claim 2 inputs the amount of electricity of each line connected to the bus of the high-resistance grounding system, calculates the amount of electricity, and determines a predetermined line in advance based on the calculation result. Ground fault detection means for detecting the continuation of a ground fault, zero-phase current detection means for detecting an effective component current from the zero-phase current of each line, and ground fault detection means A cutoff command is issued to the line having the largest effective component current detected by the zero-phase current detecting means, and if the output signal of the ground fault detecting means continues after a predetermined time, the above operation is repeated. The cutoff line selection means, the transformer bank line fault determination means for determining a fault in the direction of the transformer bank line connected to the bus, the output of the ground fault fault detection means and the output signal of the transformer bank fault direction determination means are provided. When output at the same time Characterized by comprising a transformer bank line blocking means for outputting a cutoff command to preferentially transformer bank line after a predetermined time.
Thus, the transformer bank circuit is provided with a function of identifying the direction of the fault, and when an accident is detected in the direction of the transformer bank when the continuation of the fault is detected, the circuit breaker (CB) of the transformer bank is cut off first. Will be. In the conventional protection device, since the sequence of shutting down the transmission line and then shutting down the transformer bank line is improved, it takes much time until the accident is shut down in the event of a transformer bank line accident. be able to.
[0012]
According to a third aspect of the present invention, in the protection relay device described above, an electric quantity of each line connected to the bus of the high-resistance grounding system is input, the electric quantity is calculated, and a predetermined line is predetermined based on an arithmetic unit. In a protective relay device that cuts off according to an order, a ground fault detection means for detecting the continuation of a ground fault, and an active component current detecting element having a plurality of detection levels to detect an active component current from a zero-phase current of each line. The effective current of each line detected by the zero-phase effective component current calculating means during the period when the output signal of the zero-phase current calculating means for each level and the ground fault detecting means is being output is compared with the detected level of the current. A disconnection command is output to one of the lines operating at the maximum detection level, and if the output signal of the ground fault detection means is continued, the above-described operation is repeated at predetermined time intervals, and the disconnection is performed for each level. And a line selecting means.
As a result, the zero-phase effective component current of the line connected to the bus of the high-resistance grounding system is detected, and when the accident continues, the line with a high possibility of the accident can be preferentially selected and cut off. .
[0013]
According to a fourth aspect of the present invention, there is provided the protective relay device, wherein an electric quantity of each line connected to the bus of the high-resistance grounding system is input, the electric quantity is calculated, and a predetermined line is predetermined based on the calculation result. In a protective relay device that interrupts according to an order, a ground fault detecting means for detecting a continuation of a ground fault, a zero-phase current calculating means for detecting an effective component current from a zero-phase current of each line, and a transformer connected to a bus. Means for calculating the total current of the zero-phase effective component current of the bank line of the transformer, and a total current obtained by the zero-phase effective component current total calculation means multiplied by a coefficient K smaller than 1 or more. A line selection means for preferentially selecting a line through which a zero-phase effective component current flows, and a shutoff command output to the line detected by the line selection means during a period when an output signal of the ground fault detection means is output; The output signal of the ground fault detection means continues Long as it is characterized in that a line blocking means for repeating the above operations at predetermined time intervals.
Thereby, when the fault continues in the event of a ground fault in the high-resistance grounding system, the sum of the zero-phase effective component currents (I _0BT ) of the plurality of transformer bank lines is calculated, and the zero-phase effective component of each line is calculated. A line whose current (I _OR ) is K times or more of this value (I _0BT ) (where K is 0 <K <1) is selected and cut off, and a line with a high possibility of an accident when an accident continues is selected. Since the priority is selected and cut off, the duration of the accident can be reduced.
[0014]
According to a fifth aspect of the present invention, there is provided the protective relay device, wherein an amount of electricity of each line connected to the bus of the high resistance grounding system is input, the amount of electricity is calculated, and a predetermined line is predetermined based on the calculation result. In a protective relay device that cuts off according to an order, a ground fault detection means for detecting a continuation of a ground fault, a zero-phase effective component current calculating means for detecting an effective component current from a zero-phase current of each line, and a bus connected to the bus. Neutral point total current calculating means for detecting the current flowing through the neutral point resistor installed at the neutral point of the transformer bank line and performing the total calculation, and NGR neutral point total current calculating means. A line selecting means for preferentially selecting a line having a current value equal to or larger than a value obtained by multiplying the current value by a coefficient K smaller than 1, and a line selecting means for detecting a line during a period when an output signal of the ground fault detecting means is being output. Output a cutoff command to the line to If the output signal of continuity, characterized in that a line blocking means for repeating the above operations at predetermined time intervals.
Thus, when an accident during ground fault of the high resistance grounding system is continued, the sum of currents flowing through the neutral point is disposed at the neutral point of the plurality of transformers resistor (NGR) (I _NRT ) Is determined, and the zero-phase effective component current (I _OR ) of each line is selected and cut off a line having K times or more of this value (where K is 0 <K <1). Since the line having a high possibility of an accident is preferentially selected and cut off when the vehicle is running, the accident continuation time can be shortened.
[0015]
According to a sixth aspect of the present invention, there is provided the protective relay device, wherein an electric quantity of each line connected to the bus of the high resistance grounding system is input, the electric quantity is calculated, and a predetermined line is predetermined based on the calculation result. In a protective relay device that interrupts according to an order, a ground fault accident detecting means for detecting a continuation of a ground fault accident, a zero-phase effective component current calculating means for detecting an effective component current from a zero-phase current of each line, and a line having a parallel line In the case of (2), the two-phase total zero-phase effective component current calculating means for obtaining the zero-phase active component current of the two lines total, and the zero-phase active component current calculating means during the period when the output signal of the ground fault detection means is output. The maximum line is selected from the zero-phase active currents detected by the two-phase total zero-phase active current calculation means. If the maximum line is not a parallel line, that line is selected. In the case of a parallel line, of the two lines, the zero-phase effective power distribution Outputs a cutoff command to the larger line of, if continued output signal of the ground fault detecting means, characterized in that a line blocking means for repeating the above operations at predetermined time intervals.
Thus, when the fault continues in the event of a ground fault in the high-resistance grounding system, and when a zero-phase circulating current is flowing in the parallel two-line system, the total zero-phase effective component current ( I _0RT ) is calculated, and the maximum line is selected from the zero-phase active current (I _0R ) of each line current and the total zero-phase active current (I _0RT ) of the two parallel lines. Then, by cutting off the line, the time for removing the accident can be shortened.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
(First Embodiment: Corresponding to Claim 1)
FIG. 1 is a configuration diagram of a protection system for realizing the present embodiment. Reference numeral 11 denotes a protection relay device of the present invention. FIG. 2 is a hardware configuration diagram in which the protection relay device is realized by a digital relay.
[0017]
In FIG. 1, a transmission line or a transformer bank line 1 is connected to a bus 3 or 4. The buses 3 and 4 are connected by a bus connecting line 5, and each circuit and the bus connecting line 5 are provided with a circuit breaker 2 and a current transformer 6 (hereinafter referred to as CT), respectively. Further, voltage transformers (hereinafter referred to as PTs) 7A and 7B are installed on the buses 3 and 4, respectively. Signals from these CTs and PTs are input to the protection relay device 11.
[0018]
The protective relay device 11 is provided with a ground fault detection means 12, a zero-phase current detection means 13, and a cutoff line selection means 14, and is configured to be able to output cutoff for each line.
[0019]
FIG. 2 is a diagram in which the protection relay device 11 is configured by a digital relay. An input converter 111 for each CT and PT, an analog filter (AF) 112, an analog-digital converter (ADC) 113, a preprocessor (FEP) 114, a central processing unit (CPU) 115, and a memory (ROM) for storing programs. ) 116, an input / output interface (I / O) 117 for outputting a result determined by the CPU, and an output circuit 118 for outputting each line disconnection command from the apparatus.
[0020]
FIG. 3 is a flowchart of the algorithm of the digital relay software shown in the configuration of FIG.
[0021]
In step 21, the zero-phase current is input from the CT secondary current of each line, and the bus voltage is input from the PT secondary voltage or tertiary voltage, and is constantly calculated. In step 22, it is monitored whether or not an accident has occurred in the system, and the occurrence of the accident is detected by a decrease in the bus voltage or the presence or absence of a zero-phase voltage. In step 23, it is determined whether or not the accident has continued for a predetermined time (T1). Generally, in a power system protection system, a protection section is limited, and there is a device that detects and cuts off at high speed (hereinafter referred to as a main protection device). This T1 is a time required for the main protection device to eliminate an accident. This is the time for confirmation with likelihood. If the accident has continued for a predetermined time (T1) or more, it is considered that the accident has not been eliminated by the main protection device, and the function of the protection relay device 11 of the present invention is activated, so that the protective protection measures are taken. Will do.
[0022]
In step 24, the effective component current is obtained from the zero-phase current of each line. In the power system, there is also a cable system, so if the capacitance of the line is large, a reactor is installed at the neutral point of the transformer to compensate for the lead current, and the lead current is often compensated. I have. For this reason, the current flowing through each line is increased in the lines other than the faulty line due to the current of such capacitance and reactance, and is mistaken as the faulty line. To prevent this, it is sufficient to obtain a current in phase with the current of the neutral point grounding resistor (NGR). For that purpose, the effective component of the zero-phase current is determined. The effective component of the zero-phase current is obtained based on the zero-phase voltage obtained from the bus voltage or the phase of each phase voltage at the time of an accident, and can be easily obtained in the same manner as the method employed in conventional protection relays and the like. Things.
[0023]
In step 25, the line with the largest calculated zero-phase effective component current is selected and cut off. After the maximum line of the zero-phase effective component current is selectively cut off in step 25, it is determined in step 26 whether the fault has been eliminated. If the accident has been eliminated, the present algorithm function ends.
[0024]
If the fault has not been eliminated, in step 27, after a predetermined time (T2), the maximum line of the zero-phase effective component current is selected and cut off from the remaining lines. This T2 is a time for confirming with a likelihood the time required from the cutoff output of the device to the removal of the accident. This step is repeated until accident removal is performed. The order of each step in the flowchart is an example, and may be changed as long as the gist of the present invention is not changed.
[0025]
According to the present embodiment, the zero-phase effective component current of the line connected to the bus of the high-resistance grounding system is detected, and when the accident continues, the line considered to be the accident is preferentially selected and cut off. As a result, the duration of the accident can be reduced.
[0026]
(Second embodiment: corresponds to claim 2)
FIG. 4 is a flowchart illustrating an algorithm according to the second embodiment. The figure shows the function of identifying the direction of the fault in the transformer bank line. If there is an accident in the direction of the transformer bank line at the time of a ground fault in the high-resistance grounding system, the circuit breaker of the transformer bank line first (CB).
[0027]
In the present embodiment, when a ground fault on the transformer bank side where a neutral point grounding resistor (NGR) is installed at the neutral point is detected, the magnitude of the zero-phase active component current of the transmission line is reduced. Regardless, the transformer bank is cut off, and if the accident still continues after that, a sequence is adopted in which the maximum line of the zero-phase active component current of the transmission line is selected and cut off.
[0028]
In FIG. 4, steps 31 to 33 are the same flowchart as FIG. 3 in the first embodiment. In step 34, it is determined whether or not there is an accident on the transformer bank circuit side. If the accident is on the transformer bank circuit side, in step 35, the primary and secondary circuit breakers (CB) of the transformer are cut off. In step 36, it is determined whether or not the accident is still continuing.
[0029]
If it is not an accident in the direction of the transformer bank line, in step 37, the zero-phase effective component current of each line is calculated, and in step 38, the maximum line is selected and cut off. Thereafter, it is determined in step 36 whether or not the fault has been eliminated. If the fault has not been eliminated, after a predetermined time (T2), the maximum line of the zero-phase effective component current of each line is further selected and cut off. Repeat until removal of the accident is confirmed.
[0030]
According to the present embodiment, a function to identify an accident in the direction of the transformer bank line is provided, and when an accident is detected in the direction of the transformer bank when the continuation of the accident is detected, the transformer bank line is preferentially cut off. Since the power supply (CB) is cut off, the conventional protection device improves the point that it took an extremely long time until the accident was cut off because the sequence was to cut off the transmission line and then cut off the transformer bank line. be able to.
[0031]
(Third Embodiment: Corresponding to Claim 3)
FIG. 5 shows a plurality of stages of zero-phase active component current detection level identification elements used in the third embodiment. The identification elements of the detection levels in a plurality of stages in the figure are determined as follows.
[0032]
As the minimum level of the accident detection current, it is sufficient that 30% or more of the minimum current of the neutral point resistor (NGR) can be detected in consideration of the SN ratio. Further, assuming that there is a parallel line, it is sufficient that a current equal to or more than の of the maximum current of the NGR (current at 100% ground fault) can be detected as the maximum level of the accident detection current. Therefore, the identification element of the zero-phase effective component current detection level of the line may be a plurality of stages from 0.3 times the minimum current of the NGR to から times the maximum current of the NGR.
[0033]
For example, in the case of a system configured with three NGR currents of 150 A × 3, the minimum of the identification elements of the detection level is 45 A at 30% of 150 A, and the maximum is 225 A or more, which is の of 450 A. On the other hand, in the case of two parallel lines, since the current is divided into two lines, the maximum is 225 A / 2 = 112.5 A. If a current larger than this current flows, it is determined that the line is the maximum current line. .
Therefore, as a detection level discriminating element, the range between 45A and 225A is 225A-150A-112.5A-75A-45A-22.5A as the detection sensitivity in consideration of the current capacity by NGR and the parallel two-line configuration. Need to be provided with a plurality of stages of detection elements.
[0034]
FIG. 6 is a flowchart showing an algorithm according to the fourth embodiment having the above-described multi-stage zero-phase effective component current detection function. In the figure, steps 41 to 44 are the same as in the first to third embodiments.
[0035]
In step 45, it is determined whether there is a line operating at the least sensitive level Ln (maximum current level) of the multi-stage detection element, and if so, the line is cut off in step 48. At 48, it is determined whether or not the accident has been eliminated by the interruption. If there is no line exceeding the level Ln in the step 45, a line operating at the level Ln-1 is selected in the next step 46, and the same judgment processing as described above is performed. Repeat this to eliminate the accident.
[0036]
According to the present embodiment, the zero-phase effective component current of the line connected to the bus of the high-resistance grounding system is detected, and the zero-phase effective component current detection element of the line is changed from the minimum 0.3 of the NGR current to Up to half of the NGR current is composed of multiple stages of detection elements, and the faulty line of the worst level (maximum current) is preferentially selected, and the line considered to be faulty when the fault continues is prioritized. , The accident duration can be shortened.
[0037]
(Fourth Embodiment: Corresponding to Claim 4)
FIG. 7 shows a flowchart of the algorithm in the fourth embodiment. The figure shows that if the accident continues during a ground fault
The sum of the zero-phase active component currents (I _0BT ) of a plurality of transformer bank lines is calculated, and the zero-phase active component current (I _OR ) of each line is a value obtained by _{multiplying the} total (I _0BT ) by a count K smaller than 1. This indicates that the above line is selected and cut off to remove the accident. Here, for example, if K is １／ and the magnitude I _OR of the zero-phase active component current of each line is _以上 or more of the total (I _0BT ), the line can be determined to be an accident line. Shall be.
[0038]
In FIG. 7, steps 51 to 54 are the same flowchart as FIG. 3 showing the third embodiment. Step 55 and subsequent steps show the features of the present embodiment. In step 55, the sum (I _0BT ) of the zero-phase active component currents of the plurality of transformer bank lines is calculated, and in step 56, the current is compared with the zero-phase active component currents I _{OR of} each line, and I _0R > K _-Select and cut off the line of I _0BT (where 0 <K <1). In step 57, it is determined whether or not the accident has been eliminated. If the accident has not been eliminated, the above-mentioned flow is repeated again.
[0039]
According to the present embodiment, when the fault continues in the event of a ground fault in the high-resistance grounding system, the total (I _0BT ) of the zero-phase active component currents of the plurality of transformer bank lines is calculated, and each line is calculated. Of the zero-phase effective component current (I _OR ) is K times this value (I _0BT ) (however, K is 0 <K <1). By preferentially selecting and shutting down a line that is considered to be faulty, the duration of the accident can be reduced.
[0040]
(Fifth embodiment: corresponds to claim 5)
FIG. 8 is a flowchart of an algorithm according to the fifth embodiment. The figure shows that the total value (I) of the current flowing through a neutral point resistor (NGR) installed at the neutral point of a plurality of transformers when the fault continues during a ground fault in a high resistance grounding system seeking _NRT), the zero-phase active current of each line _{(I oR)} is, K times (where K of this value _{(I NRT)} is to selectively block 0 <K <1) or more lines Is shown.
[0041]
This embodiment has the same concept as the fourth embodiment, and a detailed description is omitted.
According to the present embodiment, when an accident continues during a ground fault in a high resistance grounding system, the current flowing through a neutral point resistor (NGR) installed at the neutral point of a plurality of transformers is determined. The total value (I _NRT ) is obtained, and the zero-phase active current (I _OR ) of each line is selected and cut off by selecting a line having a value K times or more of this value (where K is 0 <K <1). By preferentially selecting and shutting down a line that seems to be an accident while the accident continues, the accident continuation time can be reduced.
[0042]
(Sixth Embodiment: Claim 6)
FIG. 9 is a flowchart of an algorithm according to the sixth embodiment. This figure shows a measure to be taken when a fault continues in the event of a ground fault in a high-resistance grounding system and a zero-phase circulating current flows in a parallel two-line system.
[0043]
Steps 71 to 74 are the same as those in FIG. 3 in the first embodiment. In step 75, the total zero-phase effective current (I _0RT ) of the two parallel lines is calculated. In step 76, the zero-phase active current (I _0R ) of each line current and the total zero-phase effective current of the two parallel lines are calculated. The maximum line is selected from (I _0RT ), and in step 78, if the maximum line is one line system, the line is cut off.
[0044]
In step 79, if the maximum line is a parallel two-line system, the line having the larger _IOR is selected and cut off from the two lines. As a result of the interruption, it is determined in step 80 whether the accident has been eliminated. As a result, if the accident has been eliminated, the operation of this function ends. If the accident has not been eliminated, the process returns to step 74 after T2 and repeats the same processing.
[0045]
According to the present embodiment, even if the accident continues during a ground fault accident in the high-resistance grounding system, and even if a zero-phase circulating current is flowing in the parallel two-line system, the fault line can be quickly established. By selecting / blocking, the time for removing the accident can be shortened.
[0046]
【The invention's effect】
As described above, according to the present invention, by disconnecting from a line having a large fault current when a fault continues, the fault elimination time can be shortened, and a neutral point such as a neutral point resistor (NGR) can be used. There is an advantage that the current withstand capability of the grounding device is small.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of a first embodiment.
FIG. 2 is a diagram in which the system configuration diagram of the first embodiment is reconfigured with digital relays.
FIG. 3 is a flowchart illustrating an algorithm according to the first embodiment.
FIG. 4 is a flowchart illustrating an algorithm according to the second embodiment.
FIG. 5 is a diagram illustrating an effective current detection element having a plurality of stages according to a third embodiment.
FIG. 6 is a flowchart illustrating an algorithm according to a third embodiment.
FIG. 7 is a flowchart illustrating an algorithm according to a fourth embodiment.
FIG. 8 is a flowchart illustrating an algorithm according to a fifth embodiment.
FIG. 9 is a flowchart illustrating an algorithm according to a fifth embodiment.
FIG. 10 is a configuration diagram of a conventional protection relay device.
FIG. 11 is a flowchart showing an algorithm of a conventional protection relay device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Transmission line circuit or transformer bank line, 2 ... Circuit breaker, 3,4 ... Bus, 5 ... Bus connecting line, 6 ... Current transformer, 7A, 7B ..Voltage transformer, 11 protection relay device, 12 ground fault detection means, 13 zero-phase current detection means, 14 cut-off circuit selection means, 111 CT, PT conversion device, 112: analog filter, 113: analog-to-digital converter, 114: FEP, 115: CPU, 116: ROM, 117: I / O, 118 ... -Each line cutoff command, 201: transformer bank, 202: transmission line, 203, 204, 205 ... breaker, 206: transmission line protection device

Claims

In a protective relay device that inputs the amount of electricity of each line connected to the bus of the high-resistance grounding system, calculates the amount of electricity, and cuts off a predetermined line based on the operation result in a predetermined order,
Ground fault detection means for detecting continuation of the ground fault,
Zero-phase current detection means for detecting an effective component current from the zero-phase current of each line,
According to the output signal of the ground fault detection means, a cutoff command is issued to the line having the largest effective component current detected by the zero-phase current detection means, and after a predetermined time, the output signal of the ground fault detection means continues. And a cutoff line selecting means for repeating the above operation.

In a protective relay device that inputs the amount of electricity of each line connected to the bus of the high-resistance grounding system, calculates the amount of electricity, and cuts off a predetermined line based on the operation result in a predetermined order,
Ground fault detection means for detecting continuation of the ground fault,
Zero-phase current detection means for detecting an effective component current from the zero-phase current of each line,
According to the output signal of the ground fault detection means, a cutoff command is issued to the line having the largest effective component current detected by the zero-phase current detection means, and after a predetermined time, the output signal of the ground fault detection means continues. If so, a cutoff line selecting means for repeating the above operation,
Transformer bank line accident determination means for determining an accident in the direction of the transformer bank line connected to the bus,
When the output of the ground fault accident detecting means and the output signal of the transformer bank line direction accident judging means are simultaneously output, a transformer bank which preferentially outputs a cutoff command to the transformer bank line after a predetermined time. A protective relay device comprising: a line cutoff unit.

In a protective relay device that inputs the amount of electricity of each line connected to the bus of the high-resistance grounding system, calculates the amount of electricity, and cuts off a predetermined line based on a calculator according to a predetermined order.
Ground fault detection means for detecting continuation of the ground fault,
Level-dependent zero-phase current calculating means for detecting an active component current from the zero-phase current of each line with an active component current detection element having a plurality of detection levels,
The effective component current of each line detected by the zero-phase effective component current calculating device is compared with the detection level of the current during the period when the output signal of the ground fault detecting device is being output, and the maximum A level cutoff circuit selecting means for outputting a cutoff command to the line operating at the detection level and repeating the above operation at predetermined time intervals if the output signal of the ground fault detection means is continued. A protective relay device characterized by the following:

In a protective relay device that inputs the amount of electricity of each line connected to the bus of the high-resistance grounding system, calculates the amount of electricity, and cuts off a predetermined line based on the operation result in a predetermined order,
Ground fault detection means for detecting continuation of the ground fault,
Zero-phase current calculation means for detecting an effective component current from the zero-phase current of each line;
Zero-phase active component current total calculating means for determining the total current of the zero-phase active component current of the transformer bank line connected to the bus,
Line selection means for preferentially selecting a line through which a zero-phase effective component current flows equal to or greater than a value obtained by multiplying the total current obtained by the zero-phase effective component current calculation means by a coefficient K smaller than 1;
During the period when the output signal of the ground fault detection means is being output, a cutoff command is output to the line detected by the line selection means, and if the output signal of the ground fault detection means continues, a predetermined A protection relay device comprising: a line disconnecting unit that repeats the above operation at time intervals.

In a protective relay device that inputs the amount of electricity of each line connected to the bus of the high-resistance grounding system, calculates the amount of electricity, and cuts off a predetermined line based on the operation result in a predetermined order,
Ground fault detection means for detecting continuation of the ground fault,
Zero-phase active component current calculating means for detecting an active component current from the zero-phase current of each line;
NGR neutral point total current calculating means for detecting a current flowing through a neutral point resistor installed at a neutral point of a transformer bank line connected to the bus and performing a total calculation;
Line selecting means for preferentially selecting a line having a current value equal to or greater than a value obtained by multiplying the current value obtained by the NGR neutral point total current calculating means by a coefficient K smaller than 1;
During the period when the output signal of the ground fault detection means is being output, a cutoff command is output to the line detected by the line selection means, and if the output signal of the ground fault detection means continues, a predetermined A protection relay device comprising: a line disconnecting unit that repeats the above operation at time intervals.

In a protective relay device that inputs the amount of electricity of each line connected to the bus of the high-resistance grounding system, calculates the amount of electricity, and cuts off a predetermined line based on the operation result in a predetermined order,
Ground fault detection means for detecting continuation of the ground fault,
Zero-phase active component current calculating means for detecting an active component current from the zero-phase current of each line;
When the lines are parallel lines, a two-line total zero-phase active component current calculating means for obtaining a zero-phase active component current of the two lines total;
Of the zero-phase active component currents detected by the zero-phase active component current calculating device and the two-line total zero-phase active component current calculating device during a period when the output signal of the ground fault detection device is being output, Select the maximum line, and if the maximum line is not a parallel line, select that line. If the maximum line is a parallel line, select the line with the larger zero-phase active component current of the two lines. A protection relay device comprising: a line disconnecting unit that outputs a disconnection command and repeats the above operation at predetermined time intervals if an output signal of the ground fault detection unit continues.