JP3614317B2

JP3614317B2 - Method and apparatus for detecting ground fault in high-voltage power receiving equipment

Info

Publication number: JP3614317B2
Application number: JP12545699A
Authority: JP
Inventors: 秀樹大澤; 博司小原
Original assignee: 財団法人東北電気保安協会
Priority date: 1999-05-06
Filing date: 1999-05-06
Publication date: 2005-01-26
Anticipated expiration: 2019-05-06
Also published as: JP2000324680A

Description

【０００１】
【発明の属する技術分野】
本発明は、自家用受電設備において、配電系統に対する保護範囲内と保護範囲外の地絡事故であることの判断を零相電流と零相電圧の位相の比較によらずに行い、前記地絡事故に対応させる動作を容易に行い得るようにする地絡事故の検出方法および検出装置に関する。
【０００２】
【従来の技術】
一般に、高圧配電系統において、供給変電所（配電用変電所）からの高圧配電線路に自家用受電設備を配置し、前記自家用受電設備の各需要部に給電する経路を構成している。一般の工業団地等においては、例えば、図９に示すように、配電用変電所１に対して高圧配電線２を介して、複数の自家用受電設備３、３ａ……を各々接続して、１系統の高圧配電線２から多数の自家用受電設備に向けて給電している。
【０００３】
ところが、前記高圧の給配電系統に対して複数の自家用受電設備を接続する状態では、前記高圧配電系統が複雑になっており、地中配電線が多く用いられている。そして、前記給配電系統を構成することにより、高圧配電系統の対地静電気容量が増加し、前記高圧配電系統に接続された自家用電気設備と配電用変電所との間で、地絡保護協調および整定が、従来の地絡方向継電器では完全に行われ得ないという事故が増加している。
【０００４】
例えば、前記地絡方向継電器の不必要動作（一般に貰い事故という）に関しては、前記図９の自家用電気設備３に地絡事故があった場合に、設備３のみの保護継電器が作動して電路から遮断し、他の自家用電気設備３ａ……に対しては正常な給電を行い得ることが望ましいものである。しかしながら、次に説明するような不都合が発生することがある。
・地絡保護協調が良好に行われない場合には、設備３に地絡事故が発生したときに、設備３ａ等の他の自家用電気設備の地絡継電器も動作して、不必要な停電に至るという問題が発生する。
・また、保護協調不適（一般に保護協調がとれないという）の状態では、設備３に地絡事故があった場合に、その設備３の保護継電器が不動作であっても、配電用変電所１の保護継電器が動作し、配電線２に接続される受電設備の全体が停電するという重大な問題が発生することがある。
【０００５】
前述したような問題が発生する原因を、図１０に示す非接地配電系統の等価回路の例を用いて説明する。前記図１０に示す例では、配電用変電所１から自家用電気設備３と、前記２つの設備の間に配置する配電線２との関係を模式的に示しており、前記配電線２には対地電圧Ｅが付与されている。前記配電用変電所１と自家用受電設備３には、各々零相変流器ＺＣＴ４、ＺＣＴ４ａが配置され、双方とも零相変流器設置点（ＺＣＴ４）に流れる電流の大きさと、零相基準入力装置（ＺＰＤ）等で検知される零相電圧（Ｖｏ）の大きさおよび相互の位相関係の３要素から判断し、地絡保護を行う地絡方向継電器（ＤＧＲ）を設けている。
【０００６】
【発明が解決しようとする課題】
前記回路において、配電系統対地静電容量Ｃ１と、自家用側対地静電容量Ｃ２が高圧ケーブルの静電容量等により発生する。例えば、配電系統１または、自家用電気設備３で地絡があった場合に、自家用電気設備の零相変流器設置点に流れる電流の方法が異なることを利用した位相比較により、地絡保護を行うことが従来の地絡保護の原理である。ところが、位相比較による方法では、前述の問題が生じることが多くなってきた。また、後述する図２に示す例に示すように、自家用電気設備３に前記零相変流器（ＺＣＴ４ａ）に流れる電流の大きさのみで判断する地絡継電器（ＧＲ）を設けた場合は、配電系統に地絡があった時に、自家用側対地静電容量Ｃ２を介して流れる電流Ｉｇ２により自家用電気設備の継電器が誤動作し、不要な停電に至ることがある。
【０００７】
近年、配電系統の大容量化、地中埋設ケーブル長の増大等により、系統の対地静電容量（Ｃ１）が増大する傾向にある。これにより、地絡点抵抗Ｒｇが比較的高い不完全地絡の場合、Ｖｏの値が小さくなる傾向がある。また、自家用電気設備のＤＧＲのＶｏタップは、固定タップであり、必要な検出感度を確保できない事例が増加している。前記問題の他に、ＤＧＲの位相の問題も関係する。一般のＤＧＲにおいては、図１２のグラフに示すように、ＩｇおよびＶｏが一定の値を超え、さらにＶｏに対してＩｇが動作範囲に入った場合に、前記ＤＧＲが動作する。なお、以下の従来例および実施例において、Ｉｇ＝３Ｉｏ（Ｉｏ：零相電流）の関係で説明する。
【０００８】
しかし、不完全地絡時に配電系統に大きな残留Ｖｏがあった場合に、自家用電気設備のＺＰＤで検出されるＶｏは、残留Ｖｏと地絡により発生するＶｏとの合成されたものとなる。この合成Ｖｏが図１２のＶｏ′となった場合には自家用電気設備のＤＧＲが不動作で、配電用変電所のＤＧＲが動作し、配電系統全体が停電するという重大な事故（波及事故）となる。前述した原因により、地絡時の正常な位相関係および、合成Ｖｏの関係からＤＧＲが不必要動作（事故範囲外で動作）または、誤不動作（事故範囲内で不動作）することがある。これに対して、自家用電気設備３側に地絡が発生した場合にのみ、自家用電気設備の継電器が動作して、事故電路を遮断することが適正な保護協調であり、適正な保護協調を得ることのできる装置が求められているのが現状である。
【０００９】
本発明は、前述したような従来の位相比較によるシーケンス的な動作原理により動作するＤＧＲの問題を解消するもので、簡便な演算処理により、保護範囲内と保護範囲外の地絡事故の判断を容易に行い得る方法と、判別に用いる装置を提供することを目的としている。
【００１０】
【課題を解決するための手段】
本発明は、配電用変電所に高圧配電線路を介して接続する自家用高圧電気設備において、高圧絶縁常時監視装置を配置してなる高圧受電設備の地絡の検知方法に関する。本発明の請求項１の発明は、前記自家用高圧電気設備に零相変流器および零相基準入力装置を介して、高圧絶縁常時監視装置を配置し、前記高圧絶縁常時監視装置には、零相変流器および零相基準入力装置から入力される零相電流および零相電圧データの演算処理を行う手段を設け、前記入力された零相電流および零相電圧データの演算処理を行う手段には、予め測定した自家用電気設備の高圧電路の対地静電容量の値を設定しておき、零相基準入力装置から入力される受電点における高圧電路の零相電圧の情報を高調波解析し、前記高調波解析から得られる各調波の電圧値にもとづいて、前記零相変流器設置点に流れる理論電流値を演算処理により算出し、前記算出した理論電流値と、前記予め設定された自家用電気設備の高圧電路の対地静電容量と前記各調波の電圧値から演算処理し算出される理論電流値から、一定の範囲を超える電流が前記零相変流器に流れたことを検知した場合に、前記異常電流の流れる原因が配電用高圧配電線路と自家用高圧電気設備のいずれかを特定する判断手段を設けることを特徴とする。
【００１１】
請求項２の発明は、配電用変電所に高圧配電線路を介して接続する自家用高圧電気設備において、前記自家用高圧電気設備に零相変流器および零相基準入力装置を介して、演算型地絡継電器を配置し、前記演算型地絡継電器には、零相変流器および零相基準入力装置から入力される零相電流および零相電圧データの演算処理を行う手段を設け、前記入力された零相電流および零相電圧データの演算処理を行う手段には、予め測定した自家用電気設備の高圧電路の対地静電容量の値を設定しておき、零相基準入力装置から入力される受電点における高圧電路の零相電圧の情報を高調波解析し、前記高調波解析から得られる各調波の電圧値にもとづいて、前記零相変流器設置点に流れる理論電流値を演算処理により算出し、前記算出した理論電流値と、実際に零相変流器設置点に流れる電流値とを比較し、前記予め設定された自家用電気設備の高圧電路の対地静電容量と前記各調波の電圧値から演算処理し算出される理論電流値から、一定の範囲を超える電流が前記零相変流器に流れたことを検知した場合に、その異常の原因が配電用高圧配電線路と自家用高圧電気設備のいずれかを演算処理により特定する判断手段を設け、前記異常電流の発生原因が自家用高圧電気設備に起因すると判断された場合に、自家用電気設備の高圧電路を遮断する制御手段を設けることを特徴とする。
【００１２】
請求項３、４の発明は、高圧受電設備の地絡の検知装置に関するもので、請求項３の発明では、自家用高圧電気設備に零相変流器および零相基準入力装置を介して配置する高圧絶縁常時監視装置と、前記高圧絶縁常時監視装置に設ける零相変流器および零相基準入力装置から入力される零相電流および零相電圧データの演算処理を行う手段と、予め測定された自家用電気設備の高圧電路の対地静電容量の値を設定しておく手段と、前記入力された零相電流および零相電圧データの演算処理を行う手段と、零相基準入力装置から入力される受電点における高圧電路の零相電圧の情報を高調波解析する手段と、前記高調波解析から得られる各調波の電圧値にもとづいて、前記零相変流器設置点に流れる理論電流値を演算処理により算出する手段と、前記算出した理論電流値と、実際に零相変流器設置点に流れる電流値とを比較する手段と、前記予め設定された自家用電気設備の高圧電路の対地静電容量と前記各調波の電圧値から演算処理し算出される理論電流値から、一定の範囲を超える電流が前記零相変流器に流れたことを検知した場合に、前記異常電流の流れる原因が配電用高圧配電線路と自家用高圧電気設備のいずれかを特定する判断する手段と、を設けることを特徴とする。
【００１３】
請求項４の発明は、自家用高圧電気設備に零相変流器および零相基準入力装置を介して配置する演算型地絡継電器と、前記演算型地絡継電器に設ける、零相変流器および零相基準入力装置から入力される零相電流および零相電圧データの演算処理を行う手段と、予め測定された自家用電気設備の高圧電路の対地静電容量の値を設定しておく手段と、前記入力された零相電流および零相電圧データの演算処理を行う手段と、零相基準入力装置から入力される受電点における高圧電路の零相電圧の情報を高調波解析する手段と、前記高調波解析から得られる各調波の電圧値にもとづいて、前記零相変流器設置点に流れる理論電流値を演算処理により算出する手段と、前記算出した理論電流値と、実際に零相変流器設置点に流れる電流値とを比較する手段と、前記予め設定された自家用電気設備の高圧電路の対地静電容量と前記各調波の電圧値から演算処理し算出される理論電流値から、一定の範囲を超える電流が前記零相変流器に流れたことを検知した場合に、その異常の原因が配電用高圧配電線路と自家用高圧電気設備のいずれかを演算処理により特定する判断手段と、前記異常電流の発生原因が自家用高圧電気設備に起因すると判断された場合に、自家用電気設備の高圧電路を遮断する制御手段と、を設けることを特徴とする。
【００１４】
前述したように構成したことにより、高圧絶縁常時監視装置を構成する場合においては、自家用受電設備の保護範囲の対地静電容量を基本データとして用いた警報を発するために、誤報が少なく、多様な電気設備に対応が可能であり、無停電で高圧電路の絶縁常時監視ができるために、電気事故を未然に防ぎ、予防保全とともに監視の作業の省力化を可能にする。そして、定期的にデータの収集を行うことにより、電路等の経年劣化等を把握でき、警報が出力された場合には、プリントアウトしたデータを解析することによって、高度な診断が可能となる。
【００１５】
また、演算型地絡継電器を用いて地絡検知手段を構成する場合には、間欠地絡、針状地絡電流波形にも対応が可能であり、配電系統の対地静電容量の大小に係わらない適切な保護協調ができ、配電系統が変化した場合でも広く対応ができる。また、被保護対象電気設備（自家用受電設備）の対地静電容量または電力ケーブルの公称断面積、亘長等を静電容量のデータとして用いるために、各電気設備に最適な保護協調ができ、誤動作、誤不動作などが低減できる。さらに、前記継電器では、残留Ｖｏや配電系統対地電圧不均一等の影響を受けないものであり、高圧絶縁常時監視装置等の微地絡検出を行う装置にも適用が可能である。そして、本発明においては、Ｖｏタップを設ける必要がなく、種々の配電系統、および自家用電気設備に適応が可能で、配電系統の変更があった場合も、タップ変更等がなく、設備に対して柔軟に適応が可能である。
【００１６】
【発明の実施の形態】
図示される例にしたがって、本発明の装置の構成を説明する。図１に示すブロック図は、零相電流信号処理回路１０を構成する回路図を示しているもので、前記信号処理回路は、入力端子１１、入力回路１２、フィルター回路１３、Ａ／Ｄ変換回路１４およびＣＰＵ１５から構成される。そして、入力端子１１からはＺＣＴ２次端子からのＺＣＴ二次電流Ｉｇが入力され、入力回路１２では、入力された電流を継電器（ＧＲ）内部で処理しやすい電圧に変換する。また、フィルター回路１３は系統の周波数（商用周波数）から、Ｎ次（配電用変電所の継電装置と類似するために必要な次数）の高調波まで通過し、高調波成分の多い電流波形も通過するように構成して、変電所の継電装置と近似した周波数特性を有する装置とする。
【００１７】
前記Ａ／Ｄ変換回路１４では、アナログ信号をＣＰＵが処理しやすいデジタル信号に変換処理して、ＣＰＵ１５に向けて信号を伝達する。前記ＣＰＵ１５では、図１１の例に示す間欠地絡波形または高調波成分の多い波形を一定時間に区切って平均した実効値検出を行うか、または、一定時間内の間欠地絡波形の積分値を求め、時間で除した平均値を求める等の処理を行い、配電用変電所の継電装置と類似した特性のものとして構成する。前記零相電流信号処理回路１０においては、入力された信号の処理を行うことにより、自家用受電設備におけるＩｇの検出特性が、配電用変電所の継電装置の特性と類似するものとなり、従来の高圧受電用継電器で発生する恐れがあったとされる間欠地絡、および、周波数特性に対する検知の問題が解決される。
【００１８】
図２に示す例は、前記図１０の場合と同様に、非接地配電系統の等価回路を説明するもので、配電用変電所１から自家用電気設備３と、前記２つの設備の間に配置する配電線２との関係を模式的に示している。この説明図において、前記配電線２には対地電圧Ｅが付与されており、前記配電用変電所１と自家用受電設備３には、各々零相変流器ＺＣＴ４、ＺＣＴ４ａが配置され、前記零相変流器（ＺＣＴ４ａ）設置点に流れる電流（Ｉｇ）の大きさおよび零相基準入力装置（ＺＰＤ）等で検知される零相電圧（Ｖｏ）の大きさおよび相互の位相関係の３要素から判断し、地絡保護を行う地絡方向継電器（ＤＧＲ）を設けている。
【００１９】
高圧配電系統の自家用電気設備に設置された継電器において、自家用電気設備に発生した地絡事故によるＺＣＴ一次電流は、保護範囲内と適確に判断して遮断器を動作させ、自家用電気設備の電路を遮断する。また、配電系統の地絡事故により、ＺＣＴ一次側に流れた電流は、保護範囲外と判断する必要がある。そこで、図３にもとづいて説明する装置を用いて、保護範囲内と範囲外の情報の判別を行い得るようにする装置を構成することができる。
【００２０】
図３に示すブロック図は、本実施例に用いる演算型地絡継電器２０を構成する回路を示しているもので、ＺＣＴからの情報を入力して信号処理を行う回路は、前記図１の零相電流信号回路と同じものとして構成している。また、ＺＰＤ（零相基準入力装置）の２次端子から出力される零相電圧（Ｖｏ）の情報は、入力端子２１から入力回路２２に入力されて、前記入力回路２２、フィルター回路２３、Ａ／Ｄ変換回路２４を通って信号処理され、ＣＰＵ２５に伝達される。前記入力回路２２は過電圧保護回路、増幅回路等から構成され、以後の処理に適当な電圧に変換されるもので、フィルター回路２３、Ａ／Ｄ変換回路２４は、前記零相電流信号処理回路の場合と同様な信号処理作用を行い、ＣＰＵ２５で処理しやすいデジタル信号に変換してから伝達する。
【００２１】
前記ＣＰＵ２５で処理された情報と自家用電気設備の対地静電容量、整定電流等のデータを、データバンク２６に蓄積しておき、以後の信号処理やデータの出力に対処させるもので、Ｉ／Ｏ回路３０から入出力端子３１を介して、他の装置に向けてデータの出力を行うこともできる。また、前記ＣＰＵ２５に接続されるデッイスプレイ２９は、Ｉｇ、ＶｏまたはＩｇ２ｎの現在値、整定Ｉｇタップ等を表示する。そして、前記ＣＰＵ２５に入力された情報にもとづいて、電路を遮断する必要があると判断される時にはトリップ回路２７から信号を出力して、開閉器を作動させるような処理を行う。
【００２２】
そして、前記演算型地絡継電器２０に設けるＣＰＵ２５においては、保護範囲と非保護範囲の判断を行って、前述したような自家用受電設備側での電路の遮断の動作を行うようにする。つまり、前記図２に示す回路において、配電線側に地絡事故が発生するとＶｏが発生し、前記ＶｏによりＣ２を経由してＺＣＴ４ａにＩｇ２が流れる。したがって、本実施例においては、従来の位相判定によらない以下の信号処理により、保護範囲、非保護範囲を判定する。
【００２３】
▲１▼ Ｖｏ波形を高調波解析し、次の数式のように各調波に展開する。
ｖｏ＝Ｖ１ｍｓｉｎωｔ＋Ｖ２ｍｓｉｎ２ωｔ＋Ｖ３ｍｓｉｎ３ωｔ＋………
但し、ｖｏ：Ｖｏの瞬時値、
Ｖ１ｍ：基本波の波高値、
Ｖ２ｍ：第２調波の波高値、
Ｖ３ｍ：第３調波の波高値、
ω：基本波の角周波数（ｒａｄ／ｓ）、
なお、第３調波以上の解析については、フィルター回路の通過周波数まで展開する。
【００２４】
▲２▼ Ｖｏ高調波解析の結果からＺＣＴ４ａに流れる理論電流値Ｉｇ２ｎを以下の数式により算出する。
Ｉｇ２ｎ＝｛（ωＣ２Ｖ１）^２＋（２ωＣ２Ｖ２）^２＋（３ωＣ２Ｖ３）^２＋……｝^１／２
但し、Ｖ１：基本波の実効値、
Ｖ２：第２調波の実効値、
Ｖ３：第３調波の実効値、
▲３▼ 保護範囲、非保護範囲の判定：
前記ＣＰＵ２５においては、設定されているプログラムにしたがって、前記計算値Ｉｇ２ｎを求める。そして、計算値Ｉｇ２ｎと実際にＺＣＴ４ａに流れる電流値を比較し、前記計算値Ｉｇ２ｎに対して、ある一定の超過裕度を勘案したＩｇ２´ からＩｇ２´´の範囲以内であれば、非保護範囲内と判断し、図４に示すようにトリップ信号を送出しないような制御を行う。また、前記計算値がＩｇ２´´を超過し、さらに継電器Ｉｇの整定タップ値を超過する電流が流れ、整定時間を超える時間流れた場合には、保護範囲と判断してトリップ信号を送出し、速やかに地絡電路を遮断する。
【００２５】
▲４▼ 残留ＶｏおよびＶｏ値の減少または増加等に対する処理：
前述したように、Ｖｏに対してＩｇ値は一定の理論的関係を持つものであり、残留ＶｏおよびＶｏ値の減少、増加に対してはＩｇ電流が追従して変化する。この追従理論電流値をＩｇ２ｎとし、一定の巾を持たせた電流値Ｉｇ２ｎ´ からＩｇ２ｎ´´の間の電流値は、前記図４に示したように保護範囲外（非保護範囲）と判断する。また、前記Ｉｇ２ｎ´ を上回り、制定タップ値を超えた電流が流れた場合に保護範囲とし、整定時間を超える時間流れた場合に、トリップ信号を送出する。
【００２６】
また、前記Ｉｇの表示は、波形の実効値の連続表示の他に、各調波毎の実効値を連続表示すること等により、絶縁劣化機器の特定や地絡パターン等のように、より高度な地絡事故分析の資料として用いることも可能となる。前記Ｉｇの計算値の情報は、データバンク２６に蓄積しておいたものを、Ｉ／Ｏ回路３０で信号処理し、データ出入力端子にプリンタを接続して出力させることにより、後で使用可能なデータとして得ることが可能となる。
【００２７】
前述したような継電器を構成する場合には、間欠地絡、針状地絡電流波形にも対応が可能であり、配電系統の対地静電容量の大小に係わらない適切な保護協調ができ、配電系統が変化した場合でも広く対応ができる。また、被保護対象電気設備（自家用受電設備）の対地静電容量または電力ケーブルの公称断面積、亘長等を静電容量のデータとして用いるために、各電気設備に最適な保護協調ができ、誤動作、誤不動作などが低減できる。さらに、前記継電器では、残留Ｖｏ、配電系統対地電圧不均一等の影響を受けないものであり、高圧絶縁常時監視装置等の微地絡検出を行う装置にも適用が可能である。
【００２８】
【高圧絶縁常時監視装置の例】
前記継電器の基本的な原理を利用すれば、ＩｇおよびＶｏの情報から自家用受電設備の保護範囲、非保護範囲を判別する方式を用いて、簡便で確実な高圧絶縁常時監視装置への応用が可能である。図６に示す例は、前記演算型地絡継電器２０の場合とは異なり、前記理論を適用可能な高圧絶縁常時監視装置４０の回路図を示している。この実施例に示す高圧絶縁常時監視装置４０においては、前記継電器の場合と同様に、入力端子４１、入力回路４２、フィルター回路４３、ゲイン調整回路４４、Ａ／Ｄ変換回路４５を介して、ＺＣＴ２次端子からのＺＣＴ二次電流Ｉｇを処理した信号が、ＣＰＵ４６に入力される。
【００２９】
そして、前記入力端子４１からはＺＣＴ２次端子からのＺＣＴ二次電流Ｉｇが入力され、入力回路４２では、入力された電流を内部で処理しやすい電圧に変換する。また、フィルター回路４３は系統の周波数（商用周波数）から、Ｎ次（配電用変電所の継電装置と類似するために必要な次数）の高調波まで通過し、高調波成分の多い電流波形も通過し、配電用変電所の継電装置と近似した周波数特性の信号を出力する。さらに、前記ゲイン調整回路４４は、ＺＣＴの製造会社または機種等により異なる変流比、変圧比（ＺＰＤ）に対応させるために、利得を自由に可変することにより、幅広い電気設備に対応させるために設けているものであり、フィルター回路からの出力電圧を調整してＡ／Ｄ変換回路４５に向けて調整した電圧値を出力する。前記Ａ／Ｄ変換回路４５では、アナログ信号をＣＰＵが処理しやすいデジタル信号に変換処理してから、ＣＰＵ４６に向けて信号を伝達する。
【００３０】
前記ＺＰＤ（零相基準入力装置）の２次端子から出力される零相電圧（Ｖｏ）の情報は、入力端子４１ａから入力回路４２ａに入力されて、前記４２ａ、フィルター回路４３ａ、ゲイン調整回路４４ａ、演算が他零相電流信号処理回路４５ａを介して信号処理され、ＣＰＵ４６に伝達される。前記入力回路４２ａは過電圧保護回路、増幅回路等から構成され、以後の処理に適当な電圧に変換されるもので、フィルター回路４３ａおよびＡ／Ｄ変換回路４５ａは、前記零相電流信号処理回路の場合と同様な信号処理作用を行う。
【００３１】
前記ＣＰＵ４６では、ＩｇおよびＶｏの信号を処理し、警報自動発報、データ蓄積処理、蓄積データの入出力等の処理を行う。そして、前記ＣＰＵでは、ディスプレイ５０に向けて表示信号を出力し、Ｉｇ、Ｉｇ２ｎのチャート、各整定値等を表示させる。また、データバンク４７は前記ＣＰＵ４６で処理された各種のデータ、または各種の警情報条件等のデータを蓄積しておき、必要に応じて外部からの操作によりデータを出力する作用を行う。Ｉ／Ｏ回路４９は被保護電路の対地静電容量、各種警報、警報条件等の入力および蓄積データの出力等を行う回路で、出入力端子４９ａを介して外部の装置に接続される。前記データ送受信回路４８は通信回線等を介して警報等のデータを、出力端子を介して出力する動作を行うものである。
【００３２】
前記図６に示す高圧絶縁常時監視装置４０において、ＣＰＵに設定しているプログラムによれば、図５のデータ記録例に示すように、Ｉｇの電流値が警報レベルを超え、さらに所定の時間（Δｔ）以上継続して検知された場合に、警報を発すると同時に、警報発報前後の一定時間のＩｇおよびＩｇｎのデータをデータバンク４７に記録する。さらに、前記Ｉｇの表示は波形の実効値連続表示の他に、各高調波毎の実効値を表示することなどにより絶縁劣化機器の特定など、より高度な自家用電気設備の絶縁診断、分析が可能となる。なお、前記図５のデータ記録例において、横軸に時間を、縦軸にＩｇの値をとっており、ＩｇはＺＣＴ一次電流、ＩｇｎはＶｏ波形から演算した理論電流値（ある程度の巾を持たせてある）で、Δｔは警報設定時間（Ｉｇの値が警報レベルを超過してから発報と判断するまでの時間）をそれぞれ示している。
【００３３】
前述したような動作を行う装置として構成したことにより、本実施例に示す高圧絶縁常時監視装置においては、自家用受電設備の保護範囲の対地容量をデータとして用いた警報を発するために、誤報が少なく、多様な電気設備に対応が可能であり、無停電で高圧電路の絶縁常時監視ができるために、電気事故を未然に防ぎ、予防保全とともに監視の作業の省力化を可能にする。また、定期的にデータの収集を行うことにより、電路等の経年劣化等を把握でき、警報が出力された場合には、プリントアウトしたデータを解析することによって、高度な診断が可能となる。
【００３４】
前記実施例に示した演算型地絡継電器２０および、高圧絶縁常時監視装置４０は、図７、８に示すように、高圧電路のＩｇデータを得る方法を用い、自家用受電設備の電路に接続して用いることができる。図７の接続方式は、前記継電器と高圧絶縁常時監視装置の双方に適用可能な例を示すもので、専用のＺＣＴ４を用い、前記ＺＣＴの二次電流を直接装置に入力させてデータを得るようにする。また、図８に示す例は、既設のＺＣＴ４を利用する場合を示しており、前記ＺＣＴ４に接続したＧＲ７またはＤＧＲのＺＣＴ二次端子間の電圧を利用し、高圧絶縁常時監視装置４０によるＩｇの検知に用いている。つまり、前記図７に示す接続例では、高圧絶縁常時監視装置４０に対する専用回路として構成されるものであるが、図８のように接続する場合には、兼用のＺＣＴを配置して設けることにより、継電器と高圧絶縁常時監視装置との双方に適用することが可能である。
【００３５】
【発明の効果】
本発明の装置は前述したように構成しているものであるから、前記継電器を構成する場合には、間欠地絡、針状地絡電流波形にも対応が可能であり、配電系統の対地静電容量の大小に係わらない適切な保護協調ができ、配電系統が変化した場合でも広く対応ができる。また、被保護対象電気設備（自家用受電設備）の対地静電容量または電力ケーブルの公称断面積、亘長等を静電容量のデータとして用いるために、各電気設備に最適な保護協調ができ、誤動作、誤不動作などが低減できる。さらに、前記継電器では、残留Ｖｏや配電系統対地電圧不均一等の影響を受けないものであり、高圧絶縁常時監視装置等の微地絡検出を行う装置にも適用が可能である。
【００３６】
また、高圧絶縁常時監視装置を構成する場合においては、自家用受電設備の保護範囲の対地容量をデータとして用いた警報を発するために、誤報が少なく、多様な電気設備に対応が可能であり、無停電で高圧電路の絶縁常時監視ができるために、電気事故を未然に防ぎ、予防保全とともに監視の作業の省力化を可能にする。そして、定期的にデータの収集を行うことにより、電路等の経年劣化等を把握でき、警報が出力された場合には、プリントアウトしたデータを解析することによって、高度な診断が可能となる。そして、本発明においては、Ｖｏタップを設ける必要がなく、種々の配電系統、および自家用電気設備に適応が可能で、配電系統の変更があった場合も、タップ変更等がなく、設備に対して柔軟に適応が可能である。
【図面の簡単な説明】
【図１】本発明の零相電流信号処理回路の構成を示すブロック図である。
【図２】非接地配電系統の等価回路の説明図である。
【図３】演算型地絡継電器の回路構成を示すブロック図である。
【図４】保護範囲の判定を行う作用の説明図である。
【図５】警報時等のデータの説明のグラフである。
【図６】高圧絶縁常時監視装置の回路構成を示すブロック図である。
【図７】専用のＺＣＴを使用する例の説明図である。
【図８】既設のＺＣＴを使用する例の説明図である。
【図９】一般の高圧配電系統の説明図である。
【図１０】自家用側の地絡時の非接地配電系統の等価回路図である。
【図１１】間欠地絡発生時の地絡電流変化例の説明図である。
【図１２】ＤＧＲの位相特性の説明図である。
【符号の説明】
１配電用変電所、２配電線、３自家用受電設備、
４ＺＣＴ、５ＧＲまたはＤＧＲ、６ＺＰＤ、７ＧＲ、
１０零相電流信号処理回路、１１入力端子、１２入力回路、
１３フィルター回路、１４Ａ／Ｄ変換回路、１５ＣＰＵ、
２０演算型地絡継電器、２１入力端子、２２入力回路、
２３フィルター回路、２４Ａ／Ｄ変換回路、２５ＣＰＵ、
２６データバンク、２７トリップ回路、２８出力端子、
２９ディスプレイ、３０Ｉ／Ｏ回路、３１出力端子、
４０高圧絶縁常時監視装置、４１、４１ａ入力端子、
４２、４２ａ入力回路、４３、４３ａフィルター回路、
４４、４４ａゲイン調整回路、４５、４５ａＡ／Ｄ変換回路、
４６ＣＰＵ、４７データバンク、４８データ送受信回路、
４９Ｉ／Ｏ回路、５０ディスプレイ。[0001]
BACKGROUND OF THE INVENTION
In the power receiving facility for private use, the ground fault is performed without determining whether the ground fault is within the protection range or outside the protection range for the distribution system without comparing the phase of the zero phase current and the zero phase voltage. The present invention relates to a ground fault detection method and a detection device that can easily perform an operation corresponding to the above.
[0002]
[Prior art]
Generally, in a high-voltage distribution system, a private power receiving facility is arranged on a high-voltage distribution line from a supply substation (distribution substation), and a path for supplying power to each demand section of the private power receiving facility is configured. In a general industrial park or the like, for example, as shown in FIG. 9, a plurality of private power receiving facilities 3, 3 a... Are connected to a distribution substation 1 via a high-voltage distribution line 2. Power is supplied from the high-voltage distribution line 2 of the system toward a large number of private power receiving facilities.
[0003]
However, in a state where a plurality of private power receiving facilities are connected to the high-voltage power distribution system, the high-voltage power distribution system is complicated, and underground distribution lines are often used. And by configuring the supply and distribution system, the electrostatic capacity of the high-voltage distribution system increases, and ground fault protection coordination and settling between the private electrical equipment connected to the high-voltage distribution system and the distribution substation However, there are an increasing number of accidents that cannot be performed completely with conventional ground fault direction relays.
[0004]
For example, regarding the unnecessary operation (generally referred to as ugly accident) of the ground fault direction relay, when there is a ground fault in the private electrical equipment 3 of FIG. It is desirable to be able to cut off and supply normal power to the other private electrical equipment 3a. However, inconvenience as described below may occur.
・ If ground fault protection coordination is not performed well, when a ground fault occurs in equipment 3, ground fault relays of other private electrical equipment such as equipment 3a will also operate, resulting in unnecessary power outages. Problem occurs.
-In addition, in the state of protection coordination inadequate (in general, protection coordination cannot be taken), if there is a ground fault in the equipment 3, even if the protective relay of the equipment 3 is inoperative, the distribution substation 1 May cause a serious problem that the entire power receiving facility connected to the distribution line 2 is interrupted.
[0005]
The cause of the above-described problem will be described using an example of an equivalent circuit of the non-grounded distribution system shown in FIG. In the example shown in FIG. 10, the relationship between the distribution substation 1 to the private electrical equipment 3 and the distribution line 2 arranged between the two facilities is schematically shown. A voltage E is applied. Zero-phase current transformers ZCT4 and ZCT4a are arranged in the distribution substation 1 and the private power receiving equipment 3, respectively, and the magnitude of the current flowing through the zero-phase current transformer installation point (ZCT4) and the zero-phase reference input A ground fault direction relay (DGR) is provided that performs ground fault protection, judging from the three factors of the magnitude of the zero phase voltage (Vo) detected by the device (ZPD) and the mutual phase relationship.
[0006]
[Problems to be solved by the invention]
In the circuit, the distribution system ground capacitance C1 and the private side ground capacitance C2 are generated by the capacitance of the high-voltage cable or the like. For example, when there is a ground fault in the distribution system 1 or the private electrical equipment 3, the ground fault protection is achieved by phase comparison using the difference in the method of current flowing through the zero-phase current transformer installation point of the private electrical equipment. It is the conventional principle of ground fault protection. However, in the method based on phase comparison, the above-mentioned problems are often generated. In addition, as shown in the example shown in FIG. 2 to be described later, in the case where a ground fault relay (GR) that judges only by the magnitude of the current flowing through the zero-phase current transformer (ZCT 4a) is provided in the private electrical equipment 3, When there is a ground fault in the distribution system, the relay of the private electrical equipment may malfunction due to the current Ig2 flowing through the private-side ground capacitance C2, which may lead to an unnecessary power failure.
[0007]
In recent years, the electrostatic capacity (C1) of the system tends to increase due to an increase in capacity of the distribution system, an increase in the length of underground cables, and the like. Thereby, in the case of an imperfect ground fault with a relatively high ground fault resistance Rg, the value of Vo tends to be small. In addition, the DGR Vo tap of the electrical equipment for private use is a fixed tap, and the number of cases where necessary detection sensitivity cannot be ensured is increasing. In addition to the above problems, the DGR phase problem is also related. In the general DGR, as shown in the graph of FIG. 12, when the Ig and Vo exceed a certain value and the Ig enters the operating range with respect to Vo, the DGR operates. In the following conventional examples and examples, a description will be given of Ig = 3Io (Io: zero-phase current).
[0008]
However, when there is a large residual Vo in the power distribution system during an incomplete ground fault, the Vo detected by the ZPD of the private electrical equipment is a combination of the residual Vo and Vo generated by the ground fault. When this combined Vo becomes Vo ′ in FIG. 12, the DGR of the private electrical equipment does not operate, the DGR of the distribution substation operates, and the entire distribution system fails. Become. Due to the above-described causes, the DGR may perform an unnecessary operation (operation outside the accident range) or a malfunction (non-operation within the accident range) due to the normal phase relationship at the time of the ground fault and the composite Vo relationship. On the other hand, only when a ground fault occurs on the private electrical equipment 3 side, the relay of the private electrical equipment operates and the accidental circuit is interrupted is the proper protective coordination, and proper protective coordination is obtained. At present, there is a need for a device that can handle such a situation.
[0009]
The present invention solves the problem of DGR that operates based on the sequence-based operation principle based on the conventional phase comparison as described above, and it is possible to judge a ground fault within and outside the protection range by simple arithmetic processing. It is an object to provide a method that can be easily performed and an apparatus used for discrimination.
[0010]
[Means for Solving the Problems]
The present invention relates to a method for detecting a ground fault in a high-voltage power receiving facility in which a high-voltage insulation constant monitoring device is arranged in a private high-voltage electrical facility connected to a distribution substation via a high-voltage distribution line. According to the first aspect of the present invention, a high-voltage insulation constant monitoring device is disposed in the private high-voltage electrical equipment via a zero-phase current transformer and a zero-phase reference input device. Means for calculating the zero-phase current and zero-phase voltage data input from the phase current transformer and the zero-phase reference input device are provided, and the means for calculating the input zero-phase current and zero-phase voltage data is provided. Sets the value of the ground capacitance of the high piezoelectric path of the private electrical equipment measured in advance, and performs harmonic analysis of the information on the zero phase voltage of the high piezoelectric path at the power receiving point input from the zero phase reference input device, Based on the voltage value of each harmonic obtained from the harmonic analysis, a theoretical current value flowing through the zero-phase current transformer installation point is calculated by an arithmetic process, and the calculated theoretical current value and the preset value are set. Ground of high-voltage path of private electrical equipment The abnormal current flows when it is detected from the theoretical current value calculated by calculating from the capacitance and the voltage value of each harmonic that a current exceeding a certain range flows to the zero-phase current transformer. Judgment means for identifying either the high-voltage distribution line for distribution or the high-voltage electric equipment for private use is provided.
[0011]
According to a second aspect of the present invention, there is provided a private high-voltage electrical facility connected to a distribution substation via a high-voltage distribution line, wherein the private high-voltage electrical facility is connected to a computation type ground via a zero-phase current transformer and a zero-phase reference input device. A relay is provided, and the arithmetic ground fault relay is provided with means for performing arithmetic processing of zero-phase current and zero-phase voltage data input from a zero-phase current transformer and a zero-phase reference input device. In the means for calculating the zero-phase current and zero-phase voltage data, the value of the ground capacitance of the high-voltage path of the private electrical equipment measured in advance is set, and the power received from the zero-phase reference input device is set. Harmonic analysis of the information on the zero-phase voltage of the high piezoelectric path at the point, and based on the voltage value of each harmonic obtained from the harmonic analysis, the theoretical current value flowing through the zero-phase current transformer installation point is calculated. The calculated theoretical current Is compared with the current value actually flowing to the zero-phase current transformer installation point, and is calculated by calculating from the ground capacitance of the high-voltage path of the preset electrical equipment and the voltage value of each harmonic. When it is detected from the theoretical current value that a current exceeding a certain range flows to the zero-phase current transformer, either the high-voltage distribution line for distribution or the high-voltage electric equipment for private use is processed. And a control means for cutting off the high piezoelectric path of the private electrical equipment when it is determined that the cause of the abnormal current is caused by the private high voltage electrical equipment.
[0012]
The third and fourth aspects of the present invention relate to a ground fault detection device for a high-voltage power receiving facility. In the third aspect of the present invention, the high-voltage electrical facility for private use is arranged via a zero-phase current transformer and a zero-phase reference input device. A high-voltage insulation constant monitoring device, a zero-phase current transformer provided in the high-voltage insulation constant monitoring device, and a means for performing arithmetic processing of zero-phase current and zero-phase voltage data input from a zero-phase reference input device; Means for setting the value of the ground capacitance of the high piezoelectric path of the private electrical equipment, means for calculating the inputted zero-phase current and zero-phase voltage data, and the zero-phase reference input device Based on the harmonic analysis of the zero phase voltage information of the high piezoelectric path at the power receiving point and the voltage value of each harmonic obtained from the harmonic analysis, the theoretical current value flowing through the zero phase current transformer installation point is calculated. Means for calculating by arithmetic processing; Means for comparing the calculated theoretical current value and the current value actually flowing to the zero-phase current transformer installation point, the ground capacitance of the high-voltage path of the preset private electrical equipment, and each harmonic When it is detected from the theoretical current value calculated by calculating from the voltage value that a current exceeding a certain range flows to the zero-phase current transformer, the cause of the abnormal current flowing is the distribution high-voltage distribution line and And a means for determining any one of the high-voltage electrical equipment for private use.
[0013]
The invention of claim 4 is a calculation type ground fault relay disposed in a high voltage electric equipment for private use through a zero phase current transformer and a zero phase reference input device, a zero phase current transformer provided in the calculation type ground fault relay, and Means for performing arithmetic processing of zero-phase current and zero-phase voltage data input from a zero-phase reference input device; means for setting a value of a ground capacitance of a high piezoelectric path of a private electric equipment measured in advance; Means for computing the input zero-phase current and zero-phase voltage data; means for harmonic analysis of zero-phase voltage information of a high piezoelectric path at a power receiving point input from a zero-phase reference input device; Based on the voltage value of each harmonic obtained from the wave analysis, means for calculating a theoretical current value flowing through the zero-phase current transformer installation point by an arithmetic process, the calculated theoretical current value, and the actual zero-phase change Compare the value of current flowing through the fluency installation point Current exceeding a certain range is calculated from a theoretical current value calculated from the ground capacitance of the high-voltage path of the preset electrical equipment and the voltage value of each harmonic. When it is detected that the current has flowed to the flow device, a judgment means for identifying, by calculation processing, whether the cause of the abnormality is a distribution high-voltage distribution line or a private high-voltage electrical facility, and the cause of the abnormal current is a private high-voltage electrical And a control means for shutting off the high piezoelectric path of the electrical equipment for private use when it is determined to be caused by the equipment.
[0014]
By configuring as described above, when configuring a high-voltage insulation constant monitoring device, an alarm is generated using the ground capacitance of the protection range of private power receiving equipment as basic data, so there are few false alarms and various It can be applied to electrical equipment and can constantly monitor insulation of high-voltage paths without a power outage, thus preventing electrical accidents and enabling labor savings in monitoring work as well as preventive maintenance. By collecting data periodically, it is possible to grasp the aging deterioration of the electric circuit and the like, and when an alarm is output, advanced diagnosis is possible by analyzing the printed data.
[0015]
In addition, when the ground fault detection means is configured using an arithmetic ground fault relay, it is possible to cope with intermittent ground faults and needle ground fault current waveforms, regardless of the magnitude of the ground capacitance of the distribution system. There is no appropriate protection coordination, and even when the distribution system changes, it can respond widely. In addition, since the ground capacitance of the electrical equipment to be protected (private power receiving equipment) or the nominal cross-sectional area of the power cable, span length, etc. are used as capacitance data, optimal protection coordination can be achieved for each electrical equipment, Malfunctions and malfunctions can be reduced. Furthermore, the relay is not affected by residual Vo, distribution system ground voltage non-uniformity, and the like, and can be applied to a device for detecting a fine ground fault such as a high voltage insulation constant monitoring device. In the present invention, it is not necessary to provide a Vo tap, and can be applied to various power distribution systems and private electrical equipment, and even if there is a change in the power distribution system, there is no tap change, etc. It can be flexibly adapted.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The configuration of the apparatus of the present invention will be described according to the illustrated example. The block diagram shown in FIG. 1 shows a circuit diagram constituting the zero-phase current signal processing circuit 10, and the signal processing circuit includes an input terminal 11, an input circuit 12, a filter circuit 13, and an A / D conversion circuit. 14 and CPU 15. The ZCT secondary current Ig from the ZCT secondary terminal is input from the input terminal 11, and the input circuit 12 converts the input current into a voltage that can be easily processed in the relay (GR). Further, the filter circuit 13 passes from the system frequency (commercial frequency) to the harmonics of the Nth order (the order necessary to be similar to the relay device of the distribution substation), and the current waveform with many harmonic components is also present. The device is configured to pass through and has a frequency characteristic approximate to that of a relay device in a substation.
[0017]
The A / D conversion circuit 14 converts the analog signal into a digital signal that can be easily processed by the CPU, and transmits the signal to the CPU 15. The CPU 15 performs effective value detection by averaging the intermittent ground fault waveform or the waveform having a lot of harmonic components shown in the example of FIG. 11 at a predetermined time, or the integrated value of the intermittent ground fault waveform within the predetermined time is obtained. The average value divided by the time is calculated, and the like, and it is configured with characteristics similar to the relay device of the distribution substation. In the zero-phase current signal processing circuit 10, by performing the processing of the input signal, the Ig detection characteristic in the private power receiving facility becomes similar to the characteristic of the relay device of the distribution substation, This solves the problem of detection of intermittent ground faults and frequency characteristics that may have occurred in the relay for receiving high voltage power.
[0018]
The example shown in FIG. 2 explains the equivalent circuit of the ungrounded distribution system, as in the case of FIG. 10, and is arranged between the distribution substation 1 to the private electrical equipment 3 and the two equipments. The relationship with the distribution line 2 is shown typically. In this explanatory diagram, a ground voltage E is applied to the distribution line 2, and zero-phase current transformers ZCT 4 and ZCT 4 a are arranged in the distribution substation 1 and the private power receiving equipment 3, respectively. Judging from the three factors of the current (Ig) flowing through the installation point of the current transformer (ZCT4a), the magnitude of the zero phase voltage (Vo) detected by the zero phase reference input device (ZPD) and the mutual phase relationship In addition, a ground fault direction relay (DGR) for ground fault protection is provided.
[0019]
In the relay installed in the private electrical equipment of the high-voltage distribution system, the ZCT primary current due to the ground fault that occurred in the private electrical equipment is judged to be within the protection range and the circuit breaker is operated, and the electrical circuit of the private electrical equipment Shut off. Moreover, it is necessary to determine that the current that has flowed to the primary side of the ZCT due to a ground fault in the distribution system is outside the protection range. Therefore, it is possible to configure an apparatus that can discriminate between the information within the protection range and the information outside the protection range by using the apparatus described with reference to FIG.
[0020]
The block diagram shown in FIG. 3 shows a circuit that constitutes the arithmetic ground fault relay 20 used in this embodiment. The circuit that performs signal processing by inputting information from the ZCT is the zero shown in FIG. It is configured as the same as the phase current signal circuit. Also, information on the zero-phase voltage (Vo) output from the secondary terminal of the ZPD (zero-phase reference input device) is input from the input terminal 21 to the input circuit 22, and the input circuit 22, filter circuit 23, A The signal is processed through the / D conversion circuit 24 and transmitted to the CPU 25. The input circuit 22 is composed of an overvoltage protection circuit, an amplifier circuit, etc., and is converted into a voltage suitable for the subsequent processing. The filter circuit 23 and the A / D conversion circuit 24 are the zero-phase current signal processing circuit. The signal processing operation is performed in the same manner as in the case, and is converted into a digital signal that can be easily processed by the CPU 25 before being transmitted.
[0021]
The information processed by the CPU 25 and data such as the ground capacitance of the electric equipment for private use and the settling current are stored in the data bank 26 to cope with subsequent signal processing and data output. Data can also be output from the circuit 30 to another device via the input / output terminal 31. The display 29 connected to the CPU 25 displays the current value of Ig, Vo or Ig2n, the settling Ig tap, and the like. Then, based on the information input to the CPU 25, when it is determined that the electric circuit needs to be interrupted, a signal is output from the trip circuit 27 to perform a process of operating the switch.
[0022]
And in CPU25 provided in the said calculation type ground fault relay 20, the protection range and the non-protection range are judged, and the operation | movement of interruption | blocking of the electric circuit by the side of the private power receiving equipment as mentioned above is performed. That is, in the circuit shown in FIG. 2, Vo occurs when a ground fault occurs on the distribution line side, and Ig2 flows to ZCT 4a via C2 by Vo. Therefore, in this embodiment, the protection range and the non-protection range are determined by the following signal processing not based on the conventional phase determination.
[0023]
(1) Harmonically analyze the Vo waveform and develop it into each harmonic as shown in the following equation.
vo = V1m sinωt + V2msin 2ωt + V3msin 3ωt +
However, vo: instantaneous value of Vo,
V1m: peak value of the fundamental wave,
V2m: peak value of the second harmonic,
V3m: peak value of the third harmonic,
ω: angular frequency of fundamental wave (rad / s),
Note that the analysis above the third harmonic is expanded to the pass frequency of the filter circuit.
[0024]
{Circle around (2)} The theoretical current value Ig2n flowing through the ZCT 4a is calculated from the result of the Vo harmonic analysis by the following formula.
Ig2n = {(ωC2 V1)²+ (2ωC2 V2)²+ (3ωC2 V3)²+ ……}^1/2
Where V1: RMS value of the fundamental wave,
V2: RMS value of the second harmonic,
V3: effective value of the third harmonic,
(3) Judgment of protection range and non-protection range:
In the CPU 25, the calculated value Ig2n is obtained according to a set program. Then, the calculated value Ig2n is compared with the current value actually flowing through the ZCT 4a. If the calculated value Ig2n is within a range of Ig2 ′ to Ig2 ″ considering a certain excess margin, the non-protection range Control is performed so as not to send a trip signal as shown in FIG. In addition, when the calculated value exceeds Ig2 ″, the current that exceeds the settling tap value of the relay Ig flows, and the time that exceeds the settling time flows, it is determined as the protection range, and a trip signal is transmitted. Immediately cut off the ground fault circuit.
[0025]
(4) Treatment for decrease or increase of residual Vo and Vo value:
As described above, the Ig value has a certain theoretical relationship with respect to Vo, and the Ig current changes following the decrease and increase of the residual Vo and Vo values. The following theoretical current value is Ig2n, and the current value between Ig2n ′ and Ig2n ″ having a certain width is determined to be out of the protection range (non-protection range) as shown in FIG. . Further, when a current exceeding the Ig2n ′ and exceeding the established tap value flows, the protection range is set, and when a time exceeding the settling time flows, a trip signal is transmitted.
[0026]
In addition to the continuous display of the effective value of the waveform, the display of the Ig can be performed at a higher level, such as by specifying an insulation deterioration device or a ground fault pattern by continuously displaying the effective value for each harmonic. It can also be used as a material for the analysis of serious ground faults. Information on the calculated value of Ig can be used later by processing the signal stored in the data bank 26 with the I / O circuit 30 and connecting it to a data input / output terminal for output. Data can be obtained.
[0027]
When configuring a relay as described above, it is possible to handle intermittent ground faults and needle-shaped ground fault current waveforms, and appropriate protection coordination is possible regardless of the magnitude of the ground capacitance of the distribution system. Even if the system changes, it can be widely handled. In addition, since the ground capacitance of the electrical equipment to be protected (private power receiving equipment) or the nominal cross-sectional area of the power cable, span length, etc. are used as capacitance data, optimal protection coordination can be achieved for each electrical equipment, Malfunctions and malfunctions can be reduced. Further, the relay is not affected by residual Vo, distribution system ground voltage non-uniformity, etc., and can be applied to a device for detecting a fine ground fault such as a high voltage insulation constant monitoring device.
[0028]
[Example of high voltage insulation constant monitoring device]
If the basic principle of the relay is used, it can be applied to a simple and reliable high voltage insulation constant monitoring device by using a method for determining the protection range and non-protection range of private power receiving equipment from Ig and Vo information. It is. The example shown in FIG. 6 is a circuit diagram of a high voltage insulation constant monitoring device 40 to which the above theory can be applied, unlike the case of the arithmetic ground fault relay 20. In the high voltage insulation constant monitoring device 40 shown in this embodiment, the ZCT2 is passed through the input terminal 41, the input circuit 42, the filter circuit 43, the gain adjustment circuit 44, and the A / D conversion circuit 45 as in the case of the relay. A signal obtained by processing the ZCT secondary current Ig from the next terminal is input to the CPU 46.
[0029]
A ZCT secondary current Ig from the ZCT secondary terminal is input from the input terminal 41, and the input circuit 42 converts the input current into a voltage that can be easily processed internally. In addition, the filter circuit 43 passes from the system frequency (commercial frequency) to the harmonics of the Nth order (the order necessary to be similar to the relay device of the distribution substation), and the current waveform with many harmonic components is also present. Passes through and outputs a signal with a frequency characteristic that approximates that of a relay device in a distribution substation. Further, the gain adjusting circuit 44 is adapted to adapt to a wide range of electrical equipment by changing the gain freely in order to correspond to a current transformation ratio and a transformation ratio (ZPD) which differ depending on the manufacturer or model of the ZCT. The output voltage from the filter circuit is adjusted, and the adjusted voltage value is output to the A / D conversion circuit 45. The A / D conversion circuit 45 converts the analog signal into a digital signal that can be easily processed by the CPU, and then transmits the signal to the CPU 46.
[0030]
Information on the zero-phase voltage (Vo) output from the secondary terminal of the ZPD (zero-phase reference input device) is input from the input terminal 41a to the input circuit 42a, and the 42a, the filter circuit 43a, and the gain adjustment circuit 44a. The calculation is signal-processed via the other zero-phase current signal processing circuit 45 a and transmitted to the CPU 46. The input circuit 42a is composed of an overvoltage protection circuit, an amplifier circuit, etc., and is converted into a voltage suitable for the subsequent processing. The filter circuit 43a and the A / D conversion circuit 45a are the same as the zero-phase current signal processing circuit. The same signal processing action is performed as in the case.
[0031]
The CPU 46 processes Ig and Vo signals, and performs processing such as automatic alarm generation, data storage processing, and input / output of stored data. Then, the CPU outputs a display signal to the display 50 to display the Ig, Ig2n chart, each set value, and the like. The data bank 47 stores various data processed by the CPU 46 or data such as various warning information conditions, and outputs data by external operation as required. The I / O circuit 49 is a circuit for inputting the ground capacitance of the protected circuit, various alarms, alarm conditions, and outputting accumulated data, and is connected to an external device via an input / output terminal 49a. The data transmission / reception circuit 48 performs an operation of outputting data such as an alarm via an output terminal via a communication line or the like.
[0032]
In the high voltage insulation constant monitoring device 40 shown in FIG. 6, according to the program set in the CPU, the current value of Ig exceeds the alarm level as shown in the data recording example of FIG. When it is continuously detected for at least Δt), an alarm is issued, and simultaneously, Ig and Ign data for a predetermined time before and after the alarm is issued are recorded in the data bank 47. In addition to the continuous display of the effective value of the waveform, the Ig display allows for more advanced insulation diagnosis and analysis of private electrical equipment, such as the identification of insulation degradation equipment by displaying the effective value for each harmonic. It becomes. In the data recording example of FIG. 5, time is plotted on the horizontal axis and Ig is plotted on the vertical axis. Ig is the ZCT primary current, Ign is a theoretical current value calculated from the Vo waveform (has a certain width). Δt indicates an alarm setting time (time from when the Ig value exceeds the alarm level until it is determined that the alarm is issued).
[0033]
By configuring as a device that performs the operation as described above, the high voltage insulation constant monitoring device shown in the present embodiment generates an alarm using the ground capacity of the protection range of the private power receiving equipment as data, so there are few false alarms. It can be applied to various electric facilities and can always monitor insulation of high-piezoelectric paths without a power failure, thus preventing electrical accidents in advance and enabling labor saving of monitoring work as well as preventive maintenance. Further, by periodically collecting data, it is possible to grasp the aging deterioration of the electric circuit and the like, and when an alarm is output, it is possible to perform advanced diagnosis by analyzing the printed data.
[0034]
The arithmetic ground fault relay 20 and the high voltage insulation constant monitoring device 40 shown in the above embodiment are connected to the electric circuit of the private power receiving facility using a method of obtaining Ig data of the high piezoelectric circuit as shown in FIGS. Can be used. The connection method of FIG. 7 shows an example applicable to both the relay and the high voltage insulation constant monitoring device, and uses a dedicated ZCT 4 to input the secondary current of the ZCT directly to the device to obtain data. To. Further, the example shown in FIG. 8 shows the case where the existing ZCT 4 is used, and the voltage between the ZCT secondary terminals of GR7 or DGR connected to the ZCT 4 is used, and the Ig of the high voltage insulation constant monitoring device 40 is used. Used for detection. That is, in the connection example shown in FIG. 7, the circuit is configured as a dedicated circuit for the high-voltage insulation constant monitoring device 40. However, in the case of connection as shown in FIG. It can be applied to both the relay and the high voltage insulation constant monitoring device.
[0035]
【The invention's effect】
Since the device of the present invention is configured as described above, in the case of configuring the relay, it is possible to cope with intermittent ground faults and acicular ground fault current waveforms. Appropriate protection coordination is possible regardless of the magnitude of the capacity, and even when the distribution system changes, it is possible to respond widely. In addition, since the ground capacitance of the electrical equipment to be protected (private power receiving equipment) or the nominal cross-sectional area of the power cable, span length, etc. are used as capacitance data, optimal protection coordination can be performed for each electrical equipment. Malfunctions and malfunctions can be reduced. Furthermore, the relay is not affected by residual Vo, distribution system ground voltage non-uniformity, and the like, and can be applied to a device that performs fine ground fault detection, such as a high voltage insulation constant monitoring device.
[0036]
In addition, in the case of configuring a high-voltage insulation constant monitoring device, an alarm is generated using the ground capacity of the protection range of the private power receiving equipment as data, so there is little false alarm and it is possible to deal with various electrical equipment. Since the insulation of the high-voltage path can be constantly monitored in the event of a power failure, electrical accidents can be prevented and preventive maintenance as well as labor saving of the monitoring work can be realized. By collecting data periodically, it is possible to grasp the aging deterioration of the electric circuit and the like, and when an alarm is output, advanced diagnosis is possible by analyzing the printed data. In the present invention, it is not necessary to provide a Vo tap, and it can be applied to various power distribution systems and private electrical equipment, and even if there is a change in the power distribution system, there is no tap change, etc. It can be flexibly adapted.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a zero-phase current signal processing circuit of the present invention.
FIG. 2 is an explanatory diagram of an equivalent circuit of a non-grounded distribution system.
FIG. 3 is a block diagram showing a circuit configuration of an arithmetic ground fault relay.
FIG. 4 is an explanatory diagram of an operation for determining a protection range.
FIG. 5 is a graph for explaining data at the time of alarm or the like.
FIG. 6 is a block diagram showing a circuit configuration of a high voltage insulation constant monitoring device.
FIG. 7 is an explanatory diagram of an example in which a dedicated ZCT is used.
FIG. 8 is an explanatory diagram of an example in which an existing ZCT is used.
FIG. 9 is an explanatory diagram of a general high-voltage power distribution system.
FIG. 10 is an equivalent circuit diagram of an ungrounded power distribution system at the time of grounding on the private side.
FIG. 11 is an explanatory diagram of an example of ground fault current change when an intermittent ground fault occurs.
FIG. 12 is an explanatory diagram of DGR phase characteristics;
[Explanation of symbols]
1 Distribution substation, 2 Distribution lines, 3 Private power receiving equipment,
4 ZCT, 5 GR or DGR, 6 ZPD, 7 GR,
10 zero-phase current signal processing circuit, 11 input terminal, 12 input circuit,
13 filter circuit, 14 A / D conversion circuit, 15 CPU,
20 operation type ground fault relay, 21 input terminal, 22 input circuit,
23 filter circuit, 24 A / D conversion circuit, 25 CPU,
26 data banks, 27 trip circuits, 28 output terminals,
29 display, 30 I / O circuit, 31 output terminal,
40 High voltage insulation constant monitoring device, 41, 41a Input terminal,
42, 42a input circuit, 43, 43a filter circuit,
44, 44a gain adjustment circuit, 45, 45a A / D conversion circuit,
46 CPU, 47 data bank, 48 data transmission / reception circuit,
49 I / O circuits, 50 displays.

Claims

In private high-voltage electrical equipment that connects to distribution substations via high-voltage distribution lines,
Through the zero-phase current transformer and the zero-phase reference input device, a high-voltage insulation constant monitoring device is arranged in the private high-voltage electrical equipment,
The high-voltage insulation constant monitoring device is provided with means for calculating zero-phase current and zero-phase voltage data input from a zero-phase current transformer and a zero-phase reference input device,
In the means for calculating the input zero-phase current and zero-phase voltage data, the value of the ground capacitance of the high piezoelectric path of the private electrical equipment measured in advance is set,
Harmonic analysis of the information of the zero-phase voltage of the high piezoelectric path at the receiving point input from the zero-phase reference input device, and based on the voltage value of each harmonic obtained from the harmonic analysis, the zero-phase current transformer is installed Calculate the theoretical current value that flows to the point by arithmetic processing,
Compare the calculated theoretical current value with the current value actually flowing to the zero-phase current transformer installation point,
From the theoretical current value calculated by calculating from the ground capacitance of the high piezoelectric path of the preset private electrical equipment and the voltage value of each harmonic, a current exceeding a certain range is supplied to the zero-phase current transformer. A method for detecting a ground fault in a high-voltage power receiving facility, characterized in that when the flow is detected, a judgment means is provided for identifying whether the cause of the abnormal current flowing is a distribution high-voltage distribution line or a private high-voltage electrical facility. .

In private high-voltage electrical equipment that connects to distribution substations via high-voltage distribution lines,
Arranging an operational ground fault relay through the zero-phase current transformer and the zero-phase reference input device in the private high-voltage electrical equipment,
The arithmetic ground fault relay is provided with means for calculating zero phase current and zero phase voltage data input from a zero phase current transformer and a zero phase reference input device,
In the means for calculating the input zero-phase current and zero-phase voltage data, the value of the ground capacitance of the high piezoelectric path of the private electrical equipment measured in advance is set,
Harmonic analysis of the information of the zero-phase voltage of the high piezoelectric path at the receiving point input from the zero-phase reference input device, and based on the voltage value of each harmonic obtained from the harmonic analysis, the zero-phase current transformer is installed Calculate the theoretical current value that flows to the point by arithmetic processing,
Compare the calculated theoretical current value and the current value that actually flows to the zero-phase current transformer installation point,
From the theoretical current value calculated by calculating from the ground capacitance of the high piezoelectric path of the preset private electrical equipment and the voltage value of each harmonic, a current exceeding a certain range is supplied to the zero-phase current transformer. When it is detected that the flow has been detected, a means for determining whether the cause of the abnormality is a distribution high-voltage distribution line or a private high-voltage electrical facility is calculated, and the cause of the abnormal current is generated in the private high-voltage electrical facility. A method for detecting a ground fault in a private high-voltage power receiving facility, comprising: a control unit configured to cut off a high piezoelectric path of the private electrical facility when it is determined to be caused.

In private high-voltage electrical equipment that connects to distribution substations via high-voltage distribution lines,
A high-voltage insulation constant monitoring device disposed in the private high-voltage electrical equipment via a zero-phase current transformer and a zero-phase reference input device;
Means for performing arithmetic processing of zero phase current and zero phase voltage data input from a zero phase current transformer and a zero phase reference input device provided in the high voltage insulation constant monitoring device;
Means for setting a value of the ground capacitance of the high piezoelectric path of the private electrical equipment measured in advance;
Means for calculating the input zero-phase current and zero-phase voltage data;
Means for harmonic analysis of information on the zero-phase voltage of the high piezoelectric path at the receiving point input from the zero-phase reference input device;
Based on the voltage value of each harmonic obtained from the harmonic analysis, means for calculating a theoretical current value flowing through the zero-phase current transformer installation point by an arithmetic process;
Means for comparing the calculated theoretical current value and the current value actually flowing to the zero-phase current transformer installation point;
From the theoretical current value calculated by calculating from the ground capacitance of the high piezoelectric path of the preset private electrical equipment and the voltage value of each harmonic, a current exceeding a certain range is supplied to the zero-phase current transformer. Means for determining whether the cause of flow of the abnormal current is one of a high-voltage distribution line for distribution and a high-voltage electric facility for private use when it is detected that
A ground fault detection device for a high-voltage power receiving facility.

In private high-voltage electrical equipment that connects to distribution substations via high-voltage distribution lines,
An operational ground fault relay disposed in the private high-voltage electrical equipment via a zero-phase current transformer and a zero-phase reference input device;
Means for performing arithmetic processing of zero-phase current and zero-phase voltage data input from a zero-phase current transformer and a zero-phase reference input device provided in the arithmetic-type ground fault relay;
Means for setting a value of the ground capacitance of the high piezoelectric path of the private electrical equipment measured in advance;
Means for calculating the input zero-phase current and zero-phase voltage data;
Means for harmonic analysis of information on the zero-phase voltage of the high piezoelectric path at the receiving point input from the zero-phase reference input device;
Based on the voltage value of each harmonic obtained from the harmonic analysis, means for calculating a theoretical current value flowing through the zero-phase current transformer installation point by an arithmetic process;
Means for comparing the calculated theoretical current value and the current value actually flowing to the zero-phase current transformer installation point;
From the theoretical current value calculated by calculating from the ground capacitance of the high piezoelectric path of the preset private electrical equipment and the voltage value of each harmonic, a current exceeding a certain range is supplied to the zero-phase current transformer. A determination means for identifying, by calculation processing, either the high-voltage distribution line for distribution or the high-voltage electrical equipment for private use when the flow is detected,
When it is determined that the cause of occurrence of the abnormal current is due to the high-voltage electrical equipment for private use, control means for cutting off the high piezoelectric path of the private electrical equipment;
An apparatus for detecting a ground fault in a private high-voltage power receiving facility.