JP3630272B2 - Digital ground fault distance relay - Google Patents
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【０００１】
【発明の属する技術分野】
本発明は電力系統の地絡事故点迄のインピーダンスを計測する地絡距離リレーの応動を制御するディジタル形距離継電装置に関する。
【０００２】
【従来の技術】
従来から電力系統の２線地絡事故をインピーダンスを計測して、所定の地絡事故点迄のインピーダンスに入ってるか否かで動作判定する方式が採用されてる。この時、２線地絡事故で事故点に電圧が残った場合、進み相 （ａｂ相事故の場合ａ相）側の計測インピーダンスのリアクタンス値が実際の事故点迄のリアクタンスより小さく（以降オーバリーチと呼称）、事故点を短く見る傾向が強い。
【０００３】
その結果、送電線の自区間事故か否かを検出する地絡第１段が次区間の事故を短く見て、自区間事故であると判断して当該送電線の電力を遮断する遮断器へ誤トリップ指令を出す可能性がある。その対策として、遅れ相の地絡第１段リレーより大きな領域の事故を検出する地絡第３段リレーが動作したら進み相の地絡第１段リレーのトリップ指令を阻止する対策を実施している。
【０００４】
送電線のｂ，ｃ相２線地絡事故時の電圧、電流の傾向は図２に示すとおりである。ここに、ｂ、ｃ相の相電流から零相電流を除いた電流Ｉｂ１２，Ｉｃ１２と零相電流Ｉ０の位相差は略９０度近くある。この両電流の大きさは、送電線の背後インピーダンスの大きさに依存し、正相背後インピーダンスが極端に大きい端子（いわゆる弱電源端子）があるとその端子から流れ込む正逆相事故電流は小さくなる。
【０００５】
逆にインピーダンスが小さくなると、その端子から流れ込む正逆相電流は大きくなり、正相電源の大きさで正逆相電流と零相電流の大きさの相対比が変わり、事故点抵抗による事故点の残り電圧との位相関係がｂ、ｃ相で変化する。ｂ，ｃ相線間の事故点抵抗Ｒａと対地間の抵抗Ｒｇとしたときのｂ，ｃ相対地事故点残り電圧ＶｂＦ，ＶｃＦは次式となる。
【数１】
ＶｂＦ＝Ｒａ・Ｉｂ１２＋Ｒｇ・３Ｉ０ （ＶｃＦ＝Ｒａ・Ｉｃ１２＋Ｒｇ・３Ｉ０） ・・・・（１）
【０００６】
図２（ａ）はＩｂ１２、Ｉｃ１２＞Ｉ０の場合、図２（ｂ）はＩｂ１２、Ｉｃ１２＜Ｉ０の場合を示す。更に、事故点抵抗は線間のＲａより、対地間抵抗Ｒｇが一般的に大きいので、共に実抵抗とすれば、ｂ，ｃ相の事故点残り電圧は零相電流位相に近くなり、ｂ，ｃ相の零相補償後のｂ，ｃ相電流Ｉｂ，Ｉｃは次式で与えられので、ｂ相の電流に対してｂ相の残り電圧は遅れ、ｃ相の電流に対してｃ相の残り電圧は進みの傾向を示す。
【０００７】
【数２】
Ｉｂ＝Ｃ１・Ｉｂ１２＋ｋ０・（Ｃ０・Ｉ０）、 Ｉｂ＝Ｃ１・Ｉｃ１２＋ｋ０・（Ｃ０・Ｉ０） ・・・・（２）
（但し、ｋ０＝（Ｚ０−Ｚ１）／Ｚ１：零相補償係数、
Ｚ１、Ｚ０：送電線路正相、零相インピーダンス
Ｃ１、Ｃ０：事故点からリレー設置点側に流れる正相、零相電流の分流比）
【０００８】
その結果、
【数３】
ＺｂＦ＝Ｉｍ［ＶｂＦ／Ｉｂ］＝負のリアクタンス ・・・・オーバリーチ
ＺｃＦ＝Ｉｍ［ＶｃＦ／Ｉｃ］＝正のリアクタンス ・・・・アンダリーチ
となる。
【０００９】
従って図３に示す系統において、リレー設置点Ａから事故点Ｆまでの線路降下インピーダンスＺＩｉｎｅはｂ，ｃ相が共に正確に測定できるが、（１）式の事故点残り電圧の影響が残り、前述の傾向を呈することになる。そのため、進み相ａ相の見るインピーダンスのリアクタンス成分は実際の事故点迄の線路インピーダンスより小さく即ち距離を近く見るオーバリーチ傾向となり、ｂ相はその逆にアンダリーチ傾向となる。
【００１０】
この対策として従来から、相手母線より近く設定されている第１段領域より広く、次区間領域の事故点までのインピーダンスを見るように設定されている第３段領域のリレー要素が動作したら、進み相の第１段領域を保護するリレー要素の遮断器引き外し指令を阻止する方式が採用されている。
【００１１】
しかし、事故点迄の線路方程式（４）式から直接、線路の正相及び零相の抵抗Ｒ１ｉｎｅ１２、Ｒ１ｉｎｅ０、インダクタンス値Ｌ１ｉｎｅ１２、Ｌ１ｉｎｅ０を算出するアルゴリズム（以降ＲＬ算出形と呼称）を採用した保護リレーの零相補償方法は次式のとおりである。以下、ｂ相のリレーで説明する。
【００１２】
【数４】
上記（７）、（８）式において、ＶｂＦは事故点残り電圧で実際には不知で保護リレーにはＶｂ（ｔ）しか入ってこないので、次式のアンダーライン部で示すように事故点残り電圧が誤差となる。
【数５】
（５）式を基本波成分ベクトル式で表記すると（１１）式となる。
【数６】
Ｖｂ＝Ｒ１ｉｎｅ・Ｉｂ１２ｒ＋ｊω・Ｌ１ｉｎｅ１２・Ｉｂ１２ｘ＋ＶｂＦ ・・・・（１１）
【００１５】
本式から、（９）、（１０）式相当でＲ１ｉｎｅ１２、Ｌ１ｉｎｅ１２を算出すると、
【数７】
＝０、 Ｉｍ：複素数のｉｍａｇｉｎａｒｙ ｐａｒｔ，＊印：共役複素数）
となる。
【００１６】
上記（１２）、（１３）式の下線部が（９）、（１０）式の下線部に相当する。ここに一般的に２つのベクトルＡ、Ｂの間で、数学的に
【数８】
Ｉｍ｛Ａ・Ｂ＊｝＝｜Ａ｜・｜Ｂ｜・ｓｉｎ（θ）、 Ｒｅ｛Ａ・Ｂ＊｝＝｜Ａ｜・｜Ｂ｜・ｃｏｓ（θ）
ここで、Ａ＝｜Ａ｜ｅｊ（θ＋φ）， Ｂ＝｜Ｂ｜ｅｊφである。
（∴ ＊ ：共役複素数、θ ：ベクトルＢに対してベクトルＡの進み位相）
が成立する。
【００１７】
この数学的な意味を踏まえて、（１２）、（１３）式で示される事故点電圧ＶｂＦと電流Ｉｂ１２ｒ、Ｉｂ１２ｘのベクトル関係を示すと図４の関係になる。同図の（ＲＦ、ω・ＬＦ）は事故点で見る同上リレーの至近点インピーダンスである。
【数９】
ベクトルＯＣ＝［ＶｂＦ・ｃｏｓ（φＶ）］／ｃｏｓ（φｒ）＝ＲＦ・｜Ｉｂ１２ｒ｜
べクトルＣＤ＝［ＶｂＦ・ｓｉｎ（φＶ−φｒ）］／ｃｏｓ（φｒ）＝ω・ＬＦ・｜Ｉｂ１２ｘ｜
【００１８】
又、従来の電気機械形、静止形リレーなどで適用されてる（以降基本波演算形と呼称）零相電流補償は、リアクタンス成分のみを考慮し、次式に示す方法を採用している。
【数１０】
（１５）、（１６）式の関係を（１２）、（１３）式と同様にベクトル図で示すと図５のようになる。同図で基準となる電流はＩｂ１２ｚである。事故点残り電圧ＷＦの電流Ｉｂ１２ｚとその９０度進み位相成分への投影分が各々
【数１１】
ベクトルＯＡ＝ＶｂＦ・ｃｏｓ（φ）＝ＲＦ・｜Ｉｂ１２ｚ｜
ベクトルＯＢ＝ＶｂＦ・ｓｉｎ（φ）＝ωＬＦ・｜Ｉｂ１２ｚ｜
となる。
【００２０】
以上から、ＲＬ算出形リレーはｂｃ相２線地絡時の事故点残り電圧が図６（ａ）の関係になった時、ｂ相の見るインピーダンスのリアクタンス成分ｊωＬＦは正、ｃ相の見るインピーダンスのリアクタンス成分ｊωＬＦは負となる状態を示している。それに反して、図６（ｂ）は基本波演算形リレーのｂ相の見るリアクタンスは負、ｃ相のリアクタンスは正である。従って、ｂ、ｃ相２線地絡時にＲＬ算出形リレーのＲ、Ｌ成分の零相電流補償係数がＫｒ＞Ｋｘの時には、ｂ相の補償電流Ｉｂ１２ｒはＩｂ１２ｘより遅れ位相傾向になる。逆にＫｒ＜Ｋｘの場合は進み位相となる。
【００２１】
【発明が解決しようとする課題】
架空線路では遅れ位相傾向が殆どであることから、従来の基本波演算形リレーでｂ相がオーバリーチ傾向であっても、ＲＬ算出形リレーではアンダリーチ傾向になる場合も生じうる。従って進み相オーバリーチ対策を実施している従来の対策をＲＬ算出形リレーにも適用することは出来ない。又事故点の残り電圧の傾向でも様相が変わりうるので、何らかの２線地絡事故でのオーバリーチ対策は必要となる。
【００２２】
本発明は上記事情に鑑みてなされたものであり、送電線路の線路方程式から抵抗Ｒ，リアクタンスｊωＬを直接算出する地絡距離リレーで、零相電流補償の抵抗分補償係数Ｋｒとリアクタンス補償係数Ｋｘの比を所定値以上に設定して、２線地絡が生じてもオーバリーチが発生して不要な動作をする可能性を防止するディジタル形地絡距離継電装置を提供することを目的としている。
【００２３】
【課題を解決するための手段】
本発明の請求項１に係るディジタル形地絡距離継電装置は、送電線の線路インピーダンスの抵抗分の零相電流補償係数とリアクタンス分の零相電流補償係数を各々個別に設定する第１の手段と、該第１の手段で設定された抵抗分の零相電流補償係数を零相電流に乗じて相電流と加算した抵抗分補償相電流とリアクタンス分の零相電流補償係数を零相電流に乗じて相電流と加算したリアクタンス補償相電流及び当該相電圧とから抵抗分、リアクタンス分を算出して、当該送電線の所定領域内で生じた地絡事故点が生じたか否かを判定する第２の手段と、該送電線に２相以上の地絡事故が発生したことを検出する第３の手段と、該第３の手段で２相以上の地絡事故と判定されたら該第２の手段の検出出力を阻止する第４の手段からなる構成とした。
【００２４】
本発明の請求項２に係るディジタル形地絡距離継電装置は、送電線の線路インピーダンスの抵抗分の零相電流補償係数とリアクタンス分の零相電流補償係数を各々個別に設定する第１の手段と、該第１の手段で設定された抵抗分の零相電流補償係数を零相電流に乗じて相電流と加算した抵抗分補償相電流とリアクタンス分の零相電流補償係数を零相電流に乗じて相電流と加算したリアクタンス補償相電流及び当該相電圧とから抵抗分、リアクタンス分を算出して、当該送電線の所定領域内で生じた地絡事故点が生じたか否かを判定する第２の手段と、該送電線に２相以上の地絡事故が発生したことを該第２の手段より広い領域をインピーダンス計測により検出する第３の手段と、該第３の手段で２相以上の地絡事故と判定されたら該第２の手段の検出出力を阻止する第４の手段からなる構成とした。
【００２５】
本発明の請求項３に係るディジタル形地絡距離継電装置は、送電線の線路インピーダンスの抵抗分の零相電流補償係数とリアクタンス分の零相電流補償係数を各々個別に設定する第１の手段と、該第１の手段で設定された抵抗分の零相電流補償係数を零相電流に乗じて相電流と加算した抵抗分補償相電流とリアクタンス分の零相電流補償係数を零相電流に乗じて相電流と加算したリアクタンス補償相電流及び当該相電圧とから抵抗分、リアクタンス分を算出して、当該送電線の所定領域内で生じた地絡事故点が生じたか否かを判定する第２の手段と、該送電線に２相以上の地絡事故が発生したことを各相の相電圧の大きさが所定値以下になったことで検出する第３の手段と、該第３の手段で２相以上の地絡事故と判定されたら該第２の手段の検出出力を阻止する第４の手段からなる構成とした。
【００２６】
本発明の請求項４に係るディジタル形地絡距離継電装置は、送電線の線路インピーダンスの抵抗分の零相電流補償係数とリアクタンス分の零相電流補償係数を各々個別に設定する第１の手段と、該第１の手段で設定された抵抗分の零相電流補償係数を零相電流に乗じて相電流と加算した抵抗分補償相電流とリアクタンス分の零相電流補償係数を零相電流に乗じて相電流と加算したリアクタンス補償相電流及び当該相電圧とから抵抗分、リアクタンス分を算出して、当該送電線の所定領域内で生じた地絡事故点が生じたか否かを判定する第２の手段と、該送電線に２相以上の地絡事故が発生したことを各相の相電流の大きさが所定値以上になったことで検出する第３の手段と、該第３の手段で２相以上の地絡事故と判定されたら該第２の手段の検出出力を阻止する第４の手段からなる構成とした。
【００２７】
このようにして、本発明のディジタル形地絡距離継電装置は、送電線の抵抗分零相補償係数（＝零相インピーダンスの抵抗分と正相インピーダンスの抵抗分の比）とリアクタンス補償係数（＝零相インピーダンスのリアクタンス分と正相インピーダンスのリアクタンス分の比）を個別に設定して、リレー設置点から地絡事故点迄の送電線のインピーダンスを抵抗、リアクタンス個別に算出する演算方式を適用したリレーにおいて、２相以上の地絡事故が生じたら、送電線の所定領域迄の事故を検出する第１段リレー要素の遮断器引き外し指令を阻止しようとするものである。
【００２８】
本発明の請求項５に係るディジタル形地絡距離継電装置は、送電線の線路インピーダンスの抵抗分の零相電流補償係数とリアクタンス分の零相電流補償係数を各々個別に設定する第１の手段と、該第１の手段で設定された抵抗分の零相電流補償係数を零相電流に乗じて相電流と加算した抵抗分補償相電流とリアクタンス分の零相電流補償係数を零相電流に乗じて相電流と加算したリアクタンス補償相電流及び当該相電圧とから抵抗分、リアクタンス分を算出して、当該送電線の所定領域内で生じた地絡事故点が生じたか否かを判定する第２の手段と、該送電線に２相以上の地絡事故が発生したことを検出する第３の手段と、該第３の手段で２相以上の地絡事故と判定されたら該第２の手段の検出出力を阻止する第４の手段と、遅れ相の地絡事故を検出する第５の手段と、前記第１の手段で設定された抵抗分の零相電流補償係数とリアクタンス分の零相電流補償係数の比が所定値以上になったら、前記第３の手段の機能を活かし、未満となったら前記第３の手段の出力を阻止して、前記第５の手段で前記第２の手段の検出出力を阻止する第６の手段とからなる構成とした。
【００２９】
このようにして、本発明のディジタル形地絡距離継電装置は、抵抗分の零相電流補償係数とリアクタンス分の零相電流補償係数の比が所定の値より大きい場合には、２相以上の地絡事故を検出したら、前記第２の手段の出力が遮断器引き外し指令を出すのを阻止し、小さい場合には、遅れ相の地絡事故の検出出力で前記第２の手段の出力を阻止しようとするものである。
【００３０】
本発明の請求項６に係るディジタル形地絡距離継電装置は、送電線の線路インピーダンスの抵抗分の零相電流補償係数とリアクタンス分の零相電流補償係数を各々個別に設定する第１の手段と、該第１の手段で設定された抵抗分の零相電流補償係数を零相電流に乗じて相電流と加算した抵抗分補償相電流とリアクタンス分の零相電流補償係数を零相電流に乗じて相電流と加算したリアクタンス補償相電流及び当該相電圧とから抵抗分、リアクタンス分を算出して、当該送電線の所定領域内で生じた地絡事故点が生じたか否かを判定する第２の手段と、該送電線に２相以上の地絡事故が発生したことを検出する第３の手段と、該第３の手段で２相以上の地絡事故と判定されたら該第２の手段の検出出力を阻止する第４の手段と、遅れ相の地絡事故を検出する第５の手段と、前記第１の手段で設定された抵抗分の零相電流補償係数とリアクタンス分の零相電流補償係数の比が所定値以上になったら、抵抗分の零相電流補償係数をリアクタンス分の零相電流補償係数と同一値とし、前記第５の手段の出力で前記第２の手段の検出出力を阻止する第７の手段とからなる構成とした。
【００３１】
このようにして、本発明のディジタル形地絡距離継電装置は、抵抗分の零相電流補償係数とリアクタンス分の零相電流補償係数の比が所定値より大きければ、両者をリアクタンス分の零相電流補償係数に合わせて、従来のアナログ形の基本波演算形リレーと同じ補償にし、且つ遅れ相の地絡事故検出で前記第２の手段の出力を阻止しようとするものである。
【００３２】
本発明の請求項７に係るディジタル形地絡距離継電装置は、電力系統の送電線の電圧、電流を所定の周期でサンプリングして取り込んで、抵抗、インダクタンスからなる送電線の線路方程式から抵抗分、インダクタンス分を直接算出して地絡事故点を検出するディジタル形地絡距離継電装置において、抵抗分の零相電流補償係数とリアクタンス分の零相電流補償係数を各々個別に設定する第１の手段と、該第１の手段で設定された抵抗分の零相電流補償係数を零相電流に乗じて相電流と加算した抵抗分補償相電流とリアクタンス分の零相電流補償係数を零相電流に乗じて相電流と加算したリアクタンス補償相電流及び当該相電圧とから抵抗分、リアクタンス分を算出して、当該送電線の所定領域内で地絡事故点が生じたか否かを判定する第２の手段と、該第１の手段で設定された抵抗分の零相電流補償係数を零相電流に乗じて相電流と加算した抵抗分補償相電流と、前記第１の手段で設定されたリアクタンス分の零相電流補償係数を零相電流に乗じて相電流と加算したリアクタンス補償相電流の位相差を算出して所定値以上になったら、該第２の手段の検出出力を阻止し、未満となったら遅れ相の地絡を検出する第５の手段の出力で前記第２の手段の検出出力を阻止する第８の手段とからなる構成とした。
【００３３】
このようにして、本発明のディジタル形地絡距離継電装置は、抵抗分の零相電流補償係数を零相電流に乗じて相電流と加算した抵抗分補償相電流と、リアクタンス分の零相電流補償係数を零相電流に乗じて相電流と加算したリアクタンス補償相電流の位相差を算出して、位相差が所定値以上ならば２線地絡と判断し、前記第２の手段の遮断器引き外し指令を阻止しようとするものである。
【００３４】
【発明の実施の形態】
図７は本発明に係る送電線用ディジタル形地絡距離継電装置を説明する実施の形態のハードウエアを示す構成図である。図において、１は対象となる送電線、２は変流器、３は変成器、４は変流器２の電流出力と電圧変成器３の電圧出力とを入力して各々適当なレベルに変換する入力変換器、５は入力変換器の電流・電圧出力をサンプリングするサンプリング保持回路、６はサンプリング保持回路５の電流・電圧出力をアナログ・ディジタル変換する回路、７は事故前後のデータを記憶する回路、８は前記電流・電圧データを用いて所定の周期で演算処理を実行してディジタル形地絡距離継電装置の動作判定及び遮断器引き外し指令を出力するための判定を行う演算回路（ＣＰＵ）、９は地絡距離リレーの動作判定結果を出力するＩ／Ｏインターフェース回路である。
【００３５】
図１は本発明の第１の実施形態の演算回路８（図７の演算回路８に相当）で行うディジタル形距離継電装置の動作判定の内容を示す図である。抵抗分、リアクタンス分各々の零相電流補償係数Ｋｒ、Ｋｘを設定し、各々を零相電流に乗じて、相電流に加算して零相補償相電流を得る。ｂ相の例で示したのが（６）式である。
【数１２】
Ｉｂ１２ｒ（ｔ）＝Ｃ１・Ｉｂ１２（ｔ）＋Ｋｒ・Ｃ０・Ｉ０（ｔ）、
Ｉｂ１２ｘ（ｔ）＝Ｃ１・Ｉｂ１２（ｔ）＋Ｋｘ・Ｃ０・Ｉ０（ｔ）
（∴Ｋｒ＝Ｒ１ｉｎｅ０／Ｒ１ｉｎｅ１２、 Ｋｘ＝Ｌ１ｉｎｅ０／Ｌ１ｉｎｅ１２）
【００３６】
この電流と相電圧とから、時刻ｔ１、ｔ２のデータを適用して、次式に基づいて抵抗、リアクタンスを算出する。
【数１３】
ここで算出された抵抗分、リアクタンス分が所定の領域内の値か否かを判定し領域内に入ってれば動作と判定する。但し、この判定結果と２相以上の地絡事故か否かを判定して２相以上の地絡事故の時は、遮断器を引き外すのを阻止するように作用する。
【００３８】
図８は本発明の第２の実施形態の２相以上の事故を検出する手段として、当該所定領域内にあることを検出する第２の手段の責務より広い領域を検出する第３の手段を説明する図である。図９に第２の手段の検出特性Ｘ１と本実施形態の第３の手段に適用する検出特性例Ｘ３を示す。同図で示すように第３の手段の検出領域の方が広く、且つ２回線送電線において、両回線にまたがる各々の回線の１線地絡事故の場合も、各回線毎に確実に当該相の事故を検出することができ、第３の手段で２相以上の地絡事故と判定されたら第２の手段の検出出力を阻止する第４の手段の動作により不要に２相動作を検出することはない。
【００３９】
図１０は本発明の第３の実施形態の２相以上の事故を検出する手段として、回線毎に電圧が所定値以下になったことで事故と検出する第３の手段を説明する図である。この方式では回線間に跨がる各々の回線の異名相１線地絡事故の場合、回線毎に第３の手段の検出要素を持たせても、２相事故と見てしまう可能性があり、第２の手段の検出出力を阻止する可能性が生じる。従って、本実施形態では、送電線に２相以上の地絡事故が発生したことを各相の相電圧の大きさが所定値以下になったことで検出する第３の手段を設け、この第３の手段で２相以上の地絡事故と判定されたら第２の手段の検出出力を阻止する第４の手段からなるものであり、１回線送電線にのみ有効な実施形態である。
【００４０】
図１１は本発明の第４の実施形態の２相以上の事故を検出する手段として、回線毎に相電流の大きさが所定値以上になったことで事故を検出する第３の手段を説明する図である。送電線に２相以上の地絡事故が発生したことを各相の相電流の大きさが所定値以上になったことで検出する第３の手段と、該第３の手段で２相以上の地絡事故と判定されたら第２の手段の検出出力を阻止する第４の手段から構成する。この方式では回線単位で相電流の大きさを検出するので、２回線に跨って異なる相で１線地絡が生じても２相以上の地絡事故と見てしまうことはない。また、この実施形態では相電流の大きさとあるが、当然相電流の変化分の大きさを見る構成にしても実現できることは言うまでもない。
【００４１】
図１２は本発明の第５の実施形態の第５の手段と第６の手段の関係を説明する図である。第５の手段は本発明の着目する相の地絡事故に対して、遅れ相の地絡事故を検出する第２の手段で検出する領域より広い領域を、ＲＬ算出形の地絡距離リレーで検出するように構成したものである。更に、第６の手段は抵抗分の零相電流補償係数Ｋｒとリアクタンス分の零相電流補償係数Ｋｘの大きさの比の大きさが所定値以上か、未満かで前記した第５の手段と、送電線の２相以上の地絡事故を検出する第３の手段の何れかを選択して、前記第２の手段の検出出力を阻止するようにしている。即ち、下記のように処理するようにしている。
【００４２】
【数１４】
Ｋｒ／Ｋｘ＞Ｋの場合：２相以上の地絡事故検出がされたら阻止
Ｋｒ／Ｋｘ＜Ｋの場合：遅れ相の地絡事故検出がされたら阻止
このようにして、この実施形態のディジタル形地絡距離継電装置は、抵抗分の零相電流補償係数とリアクタンス分の零相電流補償係数の比が所定の値より大きい場合には、２相以上の地絡事故を検出したら、前記第２の手段の出力が遮断器引き外し指令を出すのを阻止し、小さい場合には、遅れ相の地絡事故の検出出力で前記第２の手段の出力を阻止しようとするものである。
【００４３】
図１３は本発明の第６の実施形態の第５の手段と第６手段の関係を説明する図である。第５の手段は、本実施形態の着目する相の地絡事故に対して、送電線の所定領域内で地絡事故点が生じたか否かを判定する第２の手段で検出する領域より広い領域を、ＲＬ算出形の地絡距離リレーで検出するように構成したものである。
【００４４】
更に、第７の手段は抵抗分の零相電流補償係数Ｋｒとリアクタンス分の零相電流補償係数Ｋｘの大きさの比の大きさが所定値以上になったらＫｒをＫｘに等しくするようにして、前記した第５の手段で前記第２の手段の検出出力を阻止するようにしている。即ち、下記のように処理するようにしている。
【００４５】
【数１５】
Ｋｒ／Ｋｘ＞Ｋの場合：ＫｒをＫｘと同じ値として使用
Ｋｒ／Ｋｘ＜Ｋの場合：Ｋｒ、Ｋｘをそのまま使用
前記第２の手段のＲＬ算出を行い、前記した第５の手段でこの第２の手段の検出出力を阻止するようにしてる。
【００４６】
このようにして、この実施形態のディジタル形地絡距離継電装置は、抵抗分の零相電流補償係数とリアクタンス分の零相電流補償係数の比が所定値より大きければ、両者をリアクタンス分の零相電流補償係数に合わせて、従来のアナログ形の基本波演算形リレーと同じ補償にし、且つ遅れ相の地絡事故検出で前記第２の手段の出力を阻止しようとするものである。
【００４７】
図１４は本発明の第７の実施形態の第８の手段と、抵抗分の零相電流補償係数とリアクタンス分の零相電流補償係数を各々個別に設定する第１の手段、送電線の所定領域内で地絡事故点が生じたか否かを判定する第２の手段の関係を説明している。ここに（６）式で示す、抵抗分零相補償相電流Ｉｂ１２ｒとリアクタンス分零相補償相電流Ｉｂ１２ｘの位相差θを算出手法は種々ある。例えば下式でも実現できる。
【００４８】
【数１６】
この位相差θが所定値以上になったら、２相以上の地絡事故が発生したものとして、前記第２の手段の検出出力を阻止するようにし、前記位相差が所定値以下であれば、遅れ相の地絡事故を検出する第５の手段の出力で前記第２の手段の検出出力を阻止するようにしている。
【００５０】
このようにして、この実施形態のディジタル形地絡距離継電装置は、抵抗分の零相電流補償係数を零相電流に乗じて相電流と加算した抵抗分補償相電流と、リアクタンス分の零相電流補償係数を零相電流に乗じて相電流と加算したリアクタンス補償相電流の位相差を算出して、位相差が所定値以上ならば２線地絡と判断し、前記第２の手段の遮断器引き外し指令を阻止しようとするものである。
【００５１】
【発明の効果】
以上説明したように、本発明によれば、抵抗分、リアクタンス分各々の零相電流補償した相電流と相電圧から、事故点迄の抵抗、リアクタンスを直接算出するＲＬ算出形を基準にした地絡距離リレーにおいて、２線地絡時に生じるオーバリーチによる不要な動作を容易に阻止できるディジタル形地絡距離継電装置を実現することができる。
【図面の簡単な説明】
【図１】本発明のディジタル形地絡距離継電装置の第１の実施形態図。
【図２】２線地絡時の事故点電圧と電流の傾向図。
【図３】本発明の対象となる電力系統図。
【図４】本発明が解決すべき電力系統の現象の説明図。
【図５】本発明が解決すべき現象に対する、従来の地絡距離リレーの示す性能を説明する図。
【図６】本発明が解決すべき現象の説明図。
【図７】本発明のディジタル形地絡距離継電装置のハードウエアを示す構成図。
【図８】本発明のディジタル形地絡距離継電装置の第２の実施形態図。
【図９】第２手段の検出特性Ｘ１と第３手段に適用する検出特性例Ｘ３の特性図。
【図１０】本発明のディジタル形地絡距離継電装置の第３の実施形態図。
【図１１】本発明のディジタル形地絡距離継電装置の第４の実施形態図。
【図１２】本発明のディジタル形地絡距離継電装置の第５の実施形態図。
【図１３】本発明のディジタル形地絡距離継電装置の第６の実施形態図。
【図１４】本発明のディジタル形地絡距離継電装置の第７の実施形態図。
【符号の説明】
１ 送電線
２ 変流器
３ 変成器
４ 入力変換器
５ サンプリング保持回路
６ アナログディジタル変換回路
７ メモリ
８ ＣＰＵ
９ Ｉ／Ｏインターフェース[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital distance relay device that controls the response of a ground fault distance relay that measures impedance to the point of ground fault in a power system.
[0002]
[Prior art]
Conventionally, a method has been adopted in which the impedance of a two-line ground fault in the power system is measured and the operation is determined based on whether or not the impedance reaches a predetermined ground fault point. At this time, if voltage remains at the fault point due to a two-wire ground fault, the reactance value of the measured impedance on the leading phase (a phase in the case of ab phase fault) is smaller than the reactance up to the actual fault point (hereinafter referred to as overreach and ), And there is a strong tendency to look at accident points shortly.
[0003]
As a result, the ground fault first stage for detecting whether or not the transmission line is in its own section will look at the accident in the next section, determine that it is the accident in its own section, and to a circuit breaker that cuts off the power in the transmission line An erroneous trip command may be issued. As a countermeasure, if a ground fault third stage relay that detects an accident in a larger area than the ground phase first stage relay of the delayed phase is activated, implement a countermeasure to block the trip command of the ground fault first stage relay of the leading phase. Yes.
[0004]
The tendency of voltage and current at the time of b, c phase 2-wire ground fault of the transmission line is as shown in FIG. Here, the phase difference between the currents Ib12 and Ic12 obtained by removing the zero phase current from the b and c phase currents and the zero phase current I0 is approximately 90 degrees. The magnitude of both currents depends on the magnitude of the back impedance of the transmission line. If there is a terminal with a very large positive phase back impedance (so-called weak power supply terminal), the normal / reverse phase fault current flowing from that terminal becomes small. .
[0005]
Conversely, when the impedance is reduced, the forward / reverse phase current flowing from the terminal increases, the relative ratio of the forward / reverse phase current and the zero phase current changes depending on the magnitude of the positive phase power supply, and the fault point due to the fault point resistance is changed. The phase relationship with the remaining voltage changes between b and c phases. The b and c relative ground fault point residual voltages VbF and VcF when the fault point resistance Ra between the b and c phase lines and the resistance Rg between the ground are given by the following equations.
[Expression 1]
VbF = Ra · Ib12 + Rg · 3I0 (VcF = Ra · Ic12 + Rg · 3I0) (1)
[0006]
2A shows the case where Ib12 and Ic12> I0, and FIG. 2B shows the case where Ib12 and Ic12 <I0. Further, since the fault point resistance is generally larger than the Ra between the lines, the ground-to-ground resistance Rg is generally larger, so if both are actual resistances, the fault point residual voltage of the b and c phases will be close to the zero phase current phase. Since the b-phase and c-phase currents Ib and Ic after the zero-phase compensation of the c-phase are given by the following equation, the remaining voltage of the b-phase is delayed with respect to the current of the b-phase, and the remaining of the c-phase with respect to the current of the c-phase The voltage shows a tendency to advance.
[0007]
[Expression 2]
Ib = C1 · Ib12 + k0 · (C0 · I0), Ib = C1 · Ic12 + k0 · (C0 · I0) (2)
(Where k0 = (Z0−Z1) / Z1: zero-phase compensation coefficient,
Z1, Z0: Transmission line positive phase, zero phase impedance
C1, C0: Ratio of shunt of positive phase and zero phase current flowing from the accident point to the relay installation point side)
[0008]
as a result,
[Equation 3]
ZbF = Im [VbF / Ib] = Negative reactance ... Overreach
ZcF = Im [VcF / Ic] = Positive reactance .... underreach
It becomes.
[0009]
Therefore, in the system shown in FIG. 3, the line drop impedance ZIine from the relay installation point A to the fault point F can be accurately measured for both the b and c phases, but the influence of the fault point residual voltage in the equation (1) remains, and The tendency will be exhibited. For this reason, the reactance component of the impedance seen by the leading phase a phase is smaller than the line impedance up to the actual fault point, that is, the overreach tendency to look closer, and the b phase tends to be under reach.
[0010]
As a countermeasure, if a relay element in the third stage area, which has been set so as to see the impedance up to the fault point in the next section area, is operated, the process proceeds. A system is employed that prevents a breaker trip command for a relay element that protects the first stage region of the phase.
[0011]
However, a protection relay that employs an algorithm (hereinafter referred to as RL calculation type) that calculates the resistances R1ine12, R1ine0, inductance values L1ine12, L1ine0 of the positive and zero phases of the line directly from the equation (4) up to the point of the accident. The zero-phase compensation method is as follows. Hereinafter, a b-phase relay will be described.
[0012]
[Expression 4]
In the above formulas (7) and (8), VbF is the residual voltage at the fault point and is actually unknown and only Vb (t) enters the protection relay. The voltage becomes an error.
[Equation 5]
When Expression (5) is expressed as a fundamental wave component vector expression, Expression (11) is obtained.
[Formula 6]
Vb = R1ine · Ib12r + jω · L1ine12 · Ib12x + VbF (11)
[0015]
From this equation, when R1ine12 and L1ine12 are calculated according to equations (9) and (10),
[Expression 7]
= 0, Im: complex number of an integral part, * mark: conjugate complex number)
It becomes.
[0016]
The underlined parts in the above expressions (12) and (13) correspond to the underlined parts in the expressions (9) and (10). Here, generally between the two vectors A and B, mathematically
[Equation 8]
Im {A ・ B * } = | A | · | B | · sin (θ), Re {A · B * } = | A | ・ | B | ・ cos (θ)
Here, A = | A | ej (θ + φ) and B = | B | ejφ.
(∴ *: conjugate complex number, θ: leading phase of vector A relative to vector B)
Is established.
[0017]
Based on this mathematical meaning, the vector relationship between the fault point voltage VbF and the currents Ib12r and Ib12x expressed by the equations (12) and (13) is as shown in FIG. In the figure, (RF, ω · LF) is the close-point impedance of the relay as seen at the accident point.
[Equation 9]
Vector OC = [VbF · cos (φV)] / cos (φr) = RF · | Ib12r |
Vector CD = [VbF · sin (φV−φr)] / cos (φr) = ω · LF · | Ib12x |
[0018]
In addition, the zero-phase current compensation applied to conventional electromechanical and static relays (hereinafter referred to as a fundamental wave calculation type) adopts the method shown in the following equation, considering only the reactance component.
[Expression 10]
FIG. 5 shows the relationship between the equations (15) and (16) in the form of a vector diagram as in the equations (12) and (13). The reference current in the figure is Ib12z. The current Ib12z of the fault point residual voltage WF and its projection onto the phase component advanced by 90 degrees are respectively shown.
[Expression 11]
Vector OA = VbF · cos (φ) = RF · | Ib12z |
Vector OB = VbF · sin (φ) = ωLF · | Ib12z |
It becomes.
[0020]
From the above, in the RL calculation type relay, the reactance component jωLF of the impedance seen by the b phase is positive and the impedance seen by the c phase when the residual voltage at the fault point at the time of the bc phase 2-wire ground is in the relationship of FIG. The reactance component jωLF is negative. On the other hand, in FIG. 6B, the reactance seen by the b phase of the fundamental wave operation type relay is negative and the reactance of the c phase is positive. Accordingly, when the zero-phase current compensation coefficient of the R and L components of the RL calculation type relay is Kr> Kx at the time of b- and c-phase two-wire ground fault, the b-phase compensation current Ib12r tends to lag behind Ib12x. Conversely, when Kr <Kx, the leading phase is reached.
[0021]
[Problems to be solved by the invention]
Since there is almost a lagging phase tendency in the overhead line, even if the b-phase tends to be overreachable in the conventional fundamental wave calculation type relay, the RL calculation type relay may tend to be underreachable. Therefore, the conventional countermeasure that implements the countermeasure for the lead phase overreach cannot be applied to the RL calculation type relay. Moreover, since the aspect can change depending on the tendency of the remaining voltage at the accident point, it is necessary to take measures against overreach in the case of any two-wire ground fault.
[0022]
The present invention has been made in view of the above circumstances, and is a ground fault distance relay that directly calculates the resistance R and reactance jωL from the line equation of the transmission line, and the resistance compensation coefficient Kr and reactance compensation coefficient Kx for zero-phase current compensation. It is an object of the present invention to provide a digital ground fault distance relay device that prevents the possibility of unnecessary operation due to occurrence of overreach even if a two-wire ground fault occurs by setting the ratio of the above to a predetermined value or more .
[0023]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a digital ground fault distance relay device in which a zero-phase current compensation coefficient corresponding to a resistance of a line impedance of a transmission line and a zero-phase current compensation coefficient corresponding to a reactance are individually set. And the resistance-compensated phase current obtained by multiplying the zero-phase current by the zero-phase current compensation coefficient for the resistance set by the first means and the phase current and the zero-phase current compensation coefficient for the reactance The resistance and reactance components are calculated from the reactance compensation phase current multiplied by the phase current and added to the phase current and the phase voltage to determine whether or not a ground fault point has occurred within a predetermined area of the transmission line. A second means, a third means for detecting the occurrence of a ground fault of two or more phases in the transmission line, and the second means if the third means determines that a ground fault of two or more phases has occurred. The fourth means for blocking the detection output of the means of
[0024]
According to a second aspect of the present invention, there is provided a digital ground fault distance relay device in which a zero-phase current compensation coefficient corresponding to a resistance of a line impedance of a transmission line and a zero-phase current compensation coefficient corresponding to a reactance are individually set. And the resistance-compensated phase current obtained by multiplying the zero-phase current by the zero-phase current compensation coefficient for the resistance set by the first means and the phase current and the zero-phase current compensation coefficient for the reactance The resistance and reactance components are calculated from the reactance compensation phase current multiplied by the phase current and added to the phase current and the phase voltage to determine whether or not a ground fault point has occurred within a predetermined area of the transmission line. A second means, a third means for detecting, by impedance measurement, a region larger than the second means that a ground fault accident of two or more phases has occurred in the transmission line; If it is determined that the above ground fault has occurred, the second hand It was constructed and made of a fourth means for blocking the detection output.
[0025]
According to a third aspect of the present invention, there is provided a digital ground fault distance relay device in which a zero-phase current compensation coefficient corresponding to a resistance of a line impedance of a transmission line and a zero-phase current compensation coefficient corresponding to a reactance are individually set. And the resistance-compensated phase current obtained by multiplying the zero-phase current by the zero-phase current compensation coefficient for the resistance set by the first means and the phase current and the zero-phase current compensation coefficient for the reactance The resistance and reactance components are calculated from the reactance compensation phase current multiplied by the phase current and added to the phase current and the phase voltage to determine whether or not a ground fault point has occurred within a predetermined area of the transmission line. A second means, a third means for detecting that a ground fault of two or more phases has occurred in the power transmission line by the magnitude of the phase voltage of each phase being a predetermined value or less, and the third means If it is determined that a ground fault accident of two or more phases And a structure in which a fourth means for blocking the output out.
[0026]
According to a fourth aspect of the present invention, there is provided a digital ground fault distance relay device in which a zero-phase current compensation coefficient corresponding to a resistance of a line impedance of a transmission line and a zero-phase current compensation coefficient corresponding to a reactance are individually set. And the resistance-compensated phase current obtained by multiplying the zero-phase current by the zero-phase current compensation coefficient for the resistance set by the first means and the phase current and the zero-phase current compensation coefficient for the reactance The resistance and reactance components are calculated from the reactance compensation phase current multiplied by the phase current and added to the phase current and the phase voltage to determine whether or not a ground fault point has occurred within a predetermined area of the transmission line. A second means, a third means for detecting that a ground fault of two or more phases has occurred in the power transmission line by the magnitude of the phase current of each phase being a predetermined value or more, and the third means If it is determined that a ground fault accident of two or more phases And a structure in which a fourth means for blocking the output out.
[0027]
In this way, the digital ground fault distance relay device of the present invention has a resistance zero-phase compensation coefficient (= ratio of zero-phase impedance resistance to positive-phase impedance resistance) and reactance compensation coefficient ( = Ratio of reactance of zero-phase impedance and reactance of positive-phase impedance) is set individually, and the calculation method is applied to calculate the impedance of the transmission line from the relay installation point to the ground fault point separately by resistance and reactance When a ground fault accident of two or more phases occurs in the relay, the circuit breaker trip command for the first stage relay element for detecting the accident up to a predetermined area of the transmission line is to be blocked.
[0028]
According to a fifth aspect of the present invention, there is provided a digital ground fault distance relay device in which a zero-phase current compensation coefficient corresponding to a resistance of a line impedance of a transmission line and a zero-phase current compensation coefficient corresponding to a reactance are individually set. And the resistance-compensated phase current obtained by multiplying the zero-phase current by the zero-phase current compensation coefficient for the resistance set by the first means and the phase current and the zero-phase current compensation coefficient for the reactance The resistance and reactance components are calculated from the reactance compensation phase current multiplied by the phase current and added to the phase current and the phase voltage to determine whether or not a ground fault point has occurred within a predetermined area of the transmission line. A second means, a third means for detecting the occurrence of a ground fault of two or more phases in the transmission line, and the second means if the third means determines that a ground fault of two or more phases has occurred. The fourth means for blocking the detection output of the means, and the ground fault of the delayed phase And when the ratio of the resistance zero-phase current compensation coefficient set by the first means and the reactance zero-phase current compensation coefficient exceeds a predetermined value, the third means By taking advantage of the above function, the sixth means is configured to block the output of the third means when the number is less, and to block the detection output of the second means by the fifth means.
[0029]
In this way, the digital ground fault distance relay device of the present invention has two or more phases when the ratio of the zero-phase current compensation coefficient for resistance and the zero-phase current compensation coefficient for reactance is larger than a predetermined value. When the ground fault is detected, the output of the second means is prevented from issuing a circuit breaker trip command. It is intended to prevent.
[0030]
According to a sixth aspect of the present invention, there is provided a digital ground fault distance relay device in which a zero-phase current compensation coefficient corresponding to a resistance of a line impedance of a transmission line and a zero-phase current compensation coefficient corresponding to a reactance are individually set. And the resistance-compensated phase current obtained by multiplying the zero-phase current by the zero-phase current compensation coefficient for the resistance set by the first means and the phase current and the zero-phase current compensation coefficient for the reactance The resistance and reactance components are calculated from the reactance compensation phase current multiplied by the phase current and added to the phase current and the phase voltage to determine whether or not a ground fault point has occurred within a predetermined area of the transmission line. A second means, a third means for detecting the occurrence of a ground fault of two or more phases in the transmission line, and the second means if the third means determines that a ground fault of two or more phases has occurred. The fourth means for blocking the detection output of the means, and the ground fault of the delayed phase And when the ratio of the zero-phase current compensation coefficient for the resistance set by the first means and the zero-phase current compensation coefficient for the reactance exceeds a predetermined value, the zero phase for the resistance The current compensation coefficient is set to the same value as the zero-phase current compensation coefficient corresponding to the reactance, and the seventh means for blocking the detection output of the second means by the output of the fifth means is adopted.
[0031]
In this way, the digital ground fault distance relay device of the present invention is configured such that if the ratio of the resistance zero-phase current compensation coefficient and the reactance zero-phase current compensation coefficient is greater than a predetermined value, both are reduced to the reactance zero. According to the phase current compensation coefficient, the same compensation as that of the conventional analog type fundamental wave operation type relay is made, and the output of the second means is to be blocked by detecting a ground fault in the late phase.
[0032]
According to a seventh aspect of the present invention, there is provided a digital ground fault distance relay device that samples and takes in a voltage and current of a power transmission line of a power system at a predetermined period, and resistance from a line equation of a power transmission line composed of resistance and inductance. In the digital ground fault distance relay device that detects the ground fault point by directly calculating the inductance and inductance, the zero-phase current compensation coefficient for resistance and the zero-phase current compensation coefficient for reactance are set individually. 1 and the resistance-compensated phase current obtained by multiplying the zero-phase current by the zero-phase current compensation coefficient for the resistance set by the first means and the phase current, and the zero-phase current compensation coefficient for the reactance is zero. Calculates the resistance and reactance from the reactance compensation phase current multiplied by the phase current and added to the phase current and the phase voltage, and determines whether or not a ground fault point has occurred in the predetermined area of the transmission line Second Means, a resistance-compensated phase current obtained by multiplying the zero-phase current by the zero-phase current compensation coefficient for the resistance set by the first means and adding the phase current, and a reactance component set by the first means When the phase difference of the reactance compensation phase current obtained by multiplying the zero-phase current compensation coefficient by the zero-phase current and adding it to the phase current is equal to or greater than a predetermined value, the detection output of the second means is blocked and less than Then, an eighth means for blocking the detection output of the second means by the output of the fifth means for detecting the ground fault of the delayed phase is adopted.
[0033]
In this way, the digital ground fault distance relay device of the present invention multiplies the zero-phase current compensation coefficient for the resistance by the zero-phase current and adds it to the phase current, and the zero-phase for the reactance. The phase difference of the reactance compensation phase current obtained by multiplying the zero phase current by the current compensation coefficient and added to the phase current is calculated. If the phase difference is equal to or greater than a predetermined value, it is determined that there is a two-wire ground fault, and the second means is interrupted It is intended to prevent the device trip command.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 7 is a block diagram showing hardware of an embodiment for explaining a digital ground fault distance relay device for a transmission line according to the present invention. In the figure, 1 is a target transmission line, 2 is a current transformer, 3 is a transformer, 4 is a current output of the
[0035]
FIG. 1 is a diagram showing the contents of the operation determination of the digital distance relay device performed by the arithmetic circuit 8 (corresponding to the
[Expression 12]
Ib12r (t) = C1 · Ib12 (t) + Kr · C0 · I0 (t),
Ib12x (t) = C1 · Ib12 (t) + Kx · C0 · I0 (t)
(∴Kr = R1ine0 / R1ine12, Kx = L1ine0 / L1ine12)
[0036]
From this current and phase voltage, data at times t1 and t2 are applied, and resistance and reactance are calculated based on the following equations.
[Formula 13]
It is determined whether or not the resistance and reactance calculated here are values within a predetermined area. However, this determination result and whether or not a ground fault accident of two or more phases is determined. In the case of a ground fault accident of two or more phases, the circuit breaker is prevented from being tripped.
[0038]
FIG. 8 shows a third means for detecting an area wider than the responsibility of the second means for detecting that the vehicle is within the predetermined area as means for detecting an accident of two or more phases according to the second embodiment of the present invention. It is a figure explaining. FIG. 9 shows a detection characteristic X1 of the second means and a detection characteristic example X3 applied to the third means of the present embodiment. As shown in the figure, the detection area of the third means is wider, and in the case of a one-line ground fault of each line across both lines in a two-line transmission line, the corresponding phase is surely confirmed for each line. If the third means determines that the ground fault has two or more phases, the two-phase operation is detected unnecessarily by the action of the fourth means for blocking the detection output of the second means. There is nothing.
[0039]
FIG. 10 is a diagram for explaining a third means for detecting an accident when the voltage has fallen below a predetermined value for each line as means for detecting an accident of two or more phases according to the third embodiment of the present invention. . In this method, in the case of an uncommon phase 1-line ground fault of each line straddling between the lines, there is a possibility that even if a detection element of the third means is provided for each line, it may be regarded as a two-phase accident. The possibility of blocking the detection output of the second means arises. Therefore, in the present embodiment, there is provided a third means for detecting that a ground fault accident of two or more phases has occurred in the transmission line when the magnitude of the phase voltage of each phase becomes a predetermined value or less. This embodiment comprises the fourth means for blocking the detection output of the second means if it is determined that the ground fault accident of two or more phases is detected by means of 3, and is an embodiment effective only for one line transmission line.
[0040]
FIG. 11 illustrates a third means for detecting an accident when the magnitude of the phase current exceeds a predetermined value for each line as means for detecting an accident of two or more phases according to the fourth embodiment of the present invention. It is a figure to do. A third means for detecting the occurrence of a ground fault of two or more phases in the transmission line by the fact that the magnitude of the phase current of each phase has reached a predetermined value or more; If it is determined that there is a ground fault, the fourth means for blocking the detection output of the second means. In this method, since the magnitude of the phase current is detected in units of lines, even if a one-line ground fault occurs in different phases across the two lines, it will not be regarded as a ground fault accident of two or more phases. Further, in this embodiment, the magnitude of the phase current is used, but it goes without saying that it can be realized by a configuration in which the magnitude of the change in the phase current is observed.
[0041]
FIG. 12 is a diagram for explaining the relationship between the fifth means and the sixth means of the fifth embodiment of the present invention. The fifth means is a RL calculation type ground fault distance relay that is wider than the area detected by the second means for detecting the ground fault accident of the late phase with respect to the ground fault accident of the phase of interest of the present invention. It is comprised so that it may detect. Further, the sixth means is the fifth means described above, depending on whether the ratio of the magnitude of the resistance zero-phase current compensation coefficient Kr and the reactance zero-phase current compensation coefficient Kx is greater than or less than a predetermined value. One of the third means for detecting a ground fault of two or more phases of the transmission line is selected to block the detection output of the second means. That is, processing is performed as follows.
[0042]
[Expression 14]
If Kr / Kx> K: Stop if a ground fault is detected for two or more phases.
If Kr / Kx <K: Stop if a ground fault in the late phase is detected
In this way, the digital ground fault distance relay device according to the present embodiment has two phases when the ratio of the zero-phase current compensation coefficient for resistance and the zero-phase current compensation coefficient for reactance is larger than a predetermined value. If the above ground fault is detected, the output of the second means is prevented from issuing a circuit breaker trip command, and if it is small, the output of the second means is detected by the detection output of the delayed phase ground fault. It tries to block the output.
[0043]
FIG. 13 is a diagram for explaining the relationship between the fifth means and the sixth means of the sixth embodiment of the present invention. The fifth means is wider than the area detected by the second means for determining whether or not a ground fault point has occurred in a predetermined area of the transmission line with respect to the ground fault of the phase of interest of the present embodiment. The region is configured to be detected by an RL calculation type ground fault distance relay.
[0044]
Further, the seventh means makes Kr equal to Kx when the ratio of the magnitude of the resistance zero-phase current compensation coefficient Kr and the reactance zero-phase current compensation coefficient Kx exceeds a predetermined value. The detection means of the second means is blocked by the fifth means. That is, processing is performed as follows.
[0045]
[Expression 15]
When Kr / Kx> K: Kr is used as the same value as Kx
When Kr / Kx <K: Use Kr and Kx as they are
The RL calculation of the second means is performed, and the detection output of the second means is blocked by the fifth means.
[0046]
In this way, the digital ground fault distance relay device according to this embodiment is configured so that if the ratio of the resistance zero-phase current compensation coefficient and the reactance zero-phase current compensation coefficient is greater than a predetermined value, both are equivalent to the reactance. In accordance with the zero-phase current compensation coefficient, the same compensation as that of a conventional analog type fundamental wave arithmetic relay is performed, and the output of the second means is to be blocked by detecting a ground-phase fault in the delayed phase.
[0047]
FIG. 14 shows the eighth means of the seventh embodiment of the present invention, the first means for individually setting the resistance zero-phase current compensation coefficient and the reactance zero-phase current compensation coefficient. The relationship of the 2nd means which determines whether the ground fault point has arisen in the area | region is demonstrated. There are various methods for calculating the phase difference θ between the resistance-component zero-phase compensation phase current Ib12r and the reactance-component zero-phase compensation phase current Ib12x shown by the equation (6). For example, it can be realized by the following formula.
[0048]
[Expression 16]
If this phase difference θ is greater than or equal to a predetermined value, it is assumed that a ground fault accident of two or more phases has occurred, the detection output of the second means is blocked, and if the phase difference is less than or equal to a predetermined value, The detection output of the second means is blocked by the output of the fifth means for detecting a ground-phase fault in the late phase.
[0050]
In this way, the digital ground fault distance relay device of this embodiment multiplies the zero-phase current compensation coefficient for the resistance by the zero-phase current and adds the phase current to the resistance compensation phase current and the reactance zero The phase difference of the reactance compensation phase current obtained by multiplying the phase current compensation coefficient by the zero phase current and adding to the phase current is calculated. If the phase difference is equal to or greater than a predetermined value, it is determined that there is a two-wire ground fault. It is intended to prevent the circuit breaker trip command.
[0051]
【The invention's effect】
As described above, according to the present invention, the ground based on the RL calculation form that directly calculates the resistance and reactance up to the fault point from the phase current and the phase voltage compensated for the zero-phase current of each of the resistance and reactance. In the relay distance relay, it is possible to realize a digital ground fault distance relay device that can easily prevent an unnecessary operation due to overreach occurring at the time of a two-wire ground fault.
[Brief description of the drawings]
FIG. 1 is a first embodiment of a digital ground fault distance relay device according to the present invention.
FIG. 2 is a trend diagram of accident point voltage and current during a two-wire ground fault.
FIG. 3 is a power system diagram as an object of the present invention.
FIG. 4 is an explanatory diagram of a phenomenon of a power system to be solved by the present invention.
FIG. 5 is a diagram for explaining the performance of a conventional ground fault distance relay for a phenomenon to be solved by the present invention.
FIG. 6 is an explanatory diagram of a phenomenon to be solved by the present invention.
FIG. 7 is a block diagram showing hardware of a digital ground fault distance relay device of the present invention.
FIG. 8 is a second embodiment of the digital ground fault distance relay device of the present invention.
FIG. 9 is a characteristic diagram of a detection characteristic X1 of the second means and a detection characteristic example X3 applied to the third means.
FIG. 10 is a diagram of a third embodiment of the digital ground fault distance relay device of the present invention.
FIG. 11 is a diagram showing a fourth embodiment of the digital ground fault distance relay device of the present invention.
FIG. 12 is a diagram of a fifth embodiment of the digital ground fault distance relay device of the present invention.
FIG. 13 is a diagram showing a digital ground fault distance relay device according to a sixth embodiment of the present invention.
FIG. 14 is a seventh embodiment of the digital ground fault distance relay device of the present invention.
[Explanation of symbols]
1 Transmission line
2 Current transformer
3 Transformer
4 Input converter
5 Sampling holding circuit
6 Analog-digital conversion circuit
7 memory
8 CPU
9 I / O interface
Claims (7)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| JP36702897A JP3630272B2 (en) | 1997-12-25 | 1997-12-25 | Digital ground fault distance relay |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP36702897A JP3630272B2 (en) | 1997-12-25 | 1997-12-25 | Digital ground fault distance relay |
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| JP3630272B2 true JP3630272B2 (en) | 2005-03-16 |
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| KR100393909B1 (en) * | 2001-03-29 | 2003-08-06 | 유호전기공업주식회사 | Methol of distance relay for protecting transmission line with removal reactance effect |
| JP6362569B2 (en) * | 2015-06-10 | 2018-07-25 | 三菱電機株式会社 | Distance relay device and power line protection method |
| CN109782117B (en) * | 2019-03-29 | 2020-05-08 | 云南电网有限责任公司电力科学研究院 | Ground fault disappearance discrimination method based on amplitude adjustment of controllable voltage source |
| CN110470950B (en) * | 2019-08-16 | 2021-07-16 | 深圳供电局有限公司 | Fault location method for power transmission line |
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