JP3657447B2

JP3657447B2 - Sequence measuring method of switching switch of tap changer at load

Info

Publication number: JP3657447B2
Application number: JP32896298A
Authority: JP
Inventors: 一志源川
Original assignee: ティーエム・ティーアンドディー株式会社
Priority date: 1998-11-19
Filing date: 1998-11-19
Publication date: 2005-06-08
Anticipated expiration: 2018-11-19
Also published as: JP2000156325A

Description

【０００１】
【発明の属する技術分野】
この発明は、複数の巻線を備えた負荷時タップ切換変圧器の負荷時タップ切換器の切換開閉器のシーケンス測定方法に関するものである。
【０００２】
【従来の技術】
負荷時タップ切換変圧器は、通常、高圧側巻線に複数のタップが設けられて負荷時タップ切換器が接続された構成であり、タップの切換は、接続されているタップと切り換えられるタップ間を抵抗で橋絡し、タップの接続位置を切り換えるように構成されている。
【０００３】
負荷時タップ切換変圧器の負荷時タップ切換器で、例えば２抵抗式切換開閉器の場合の構成を図４に示す。図において、１は変圧器、２は高圧側巻線であり、中性点側に複数のタップ５が設けられている。３は低圧側巻線、４は変圧器タンク、５は高圧側巻線２に設けられた複数のタップ、６ａは高圧側ブッシング、６ｎは高圧側中性点ブッシング、７ａ、７ｂは低圧側ブッシングである。１０は負荷時タップ切換器であり、切換開閉器１１、切換開閉器１１を収容する切換開閉器容器１２、接続端子１３ａを備えたタップ選択器１３で構成されている。１４はタップ５とタップ選択器１３の接続端子１３ａの間を接続する接続リードである。１５は負荷時タップ切換器１０の操作機構、１６は操作機構１５の操作力を負荷時タップ切換器１０に伝達する操作力伝達機構であり、縦連結軸１６ａ、傘歯車機構１６ｂ、横連結軸１６ｃで構成されている。
【０００４】
負荷時タップ切換器１０の切換開閉器１１の結線図を図５（ａ）、切換開閉器１１に内蔵された電流開閉スイッチのシーケンスを図５（ｂ）に示す。図５（ａ）において、１１ａ、１１ｂはタップ選択器１３に接続する接続部、１１ｎは中性点側に接続される接続部である。２１、２２、２３、２４は切換開閉器１１に内蔵された電流開閉スイッチ、２５ａは電流開閉スイッチ２２に直列接続された限流抵抗器、２５ｂは電流開閉スイッチ２３に直列接続された限流抵抗器であり、電流開閉スイッチ２１と限流抵抗器２５ａとが直列に接続された電流開閉スイッチ２２が並列接続されて接続部１１ａに接続され、電流開閉スイッチ２４と限流抵抗器２５ｂが直列に接続された電流開閉スイッチ２３とが並列接続されて接続部１１ｂに接続され、電流開閉スイッチ２１、２２、２３、２４の中性点側は並列接続されて中性点側接続部１１ｎに接続されている。
【０００５】
変圧器１の高圧側巻線２のタップ選択器１３により選択されたタップ５は接続部１１ａに接続され、切り換えられるタップ５は接続部１１ｂに接続され、運転中は電流開閉スイッチ２１が閉路され、その他の電流開閉スイッチ２２、２３、２４は開路されている。この状態でタップ切換指令の例えば奇数タップから偶数タップへのタップ切換指令があると、電流開閉スイッチ２１、２２、２３、２４は、図５（ｂ）に示すタイミングで開閉動作し、タップ切換が行われる。即ち、電流開閉スイッチ２１がタイミングＴ₁ で開路するよりも早く電流開閉スイッチ２２が閉路し、電流開閉スイッチ２２が開路されるタイミングＴ₃ よりも早いタイミングＴ₂ で電流開閉スイッチ２３が閉路し、電流開閉スイッチ２３が開路されるよりも早いタイミングＴ₄ で電流開閉スイッチ２４が閉路するように制御される。偶数タップから奇数タップへのタップ切換指令に対しては図５（ｂ）のＢ点からＡ点に向かうシーケンスで電流開閉スイッチ２４、２３、２２、２１の順序で開閉するように制御される。
【０００６】
負荷時タップ切換器１０の切換開閉器１１は切換の都度アークが発生し、接点の消耗を伴う。各接点の消耗は、開閉のタイミング（以下切換開閉器のシーケンスと呼ぶ）の変化をもたらし、消耗が激しくなると電流開閉スイッチ２１、２２、２３、２４の許容残量がなくなり、長時間アークの発生に至り、電流開閉スイッチ２１と電流開閉スイッチ２３が同時にアークで繋がる状態となってタップ間短絡に至る問題の他、ＪＥＣ２２３０−１９８８、（参考２）の３．３．１項に示されているように変圧器の負荷率によって通常の負荷電流のみを遮断する電流開閉スイッチ２１、２４と、電流開閉スイッチ２２、２３が同時に閉極した時にタップ間を通流する橋絡電流と負荷電流の半分が重畳した電流もしくは差電流のみを遮断する電流開閉スイッチ２２、２３間の遮断消耗量の差が大きくなり、各電流開閉スイッチ２１、２２、２３、２４の開閉タイミングの相互間隔すなわち図５（ｂ）に示すタイミングＴ₁ 、Ｔ₂ 、Ｔ₃ 、Ｔ₄ が変化することとなる。
【０００７】
このようなことから負荷時タップ切換器の電流開閉スイッチの開閉間隔すなわちシーケンスは切換開閉器における電流開閉の成功、失敗に関係する重要な要素であり、接点の消耗によるシーケンスの変化状況を定期的に把握すること不可欠の事項である。
【０００８】
従来の負荷時タップ切換器１０の切換開閉器１１のシーケンス測定は、変圧器１を停止し、負荷時タップ切換器１０の切換開閉器１１を取り出し、取り出した切換開閉器１１を試験用タンクに取り付け、専用の試験装置により行われていた。その状況を図６に示す。図において、変圧器１の部分は図４に示す構成であり、高圧側巻線２、低圧側巻線３、変圧器タンク４、高圧側巻線２に設けられた電圧調整するためのタップ５、高圧側ブッシング６ａ、高圧側中性点ブッシング６ｎ、低圧側ブッシング７ａ、７ｂ、負荷時タップ切換器１０、切換開閉器１１、切換開閉器容器１２、接続端子１３ａを備えたタップ選択器１３、タップ５とタップ選択器１３の接続端子１３ａの間を接続する接続リード１４、負荷時タップ切換器１０の操作機構１５、操作機構１５の操作力を負荷時タップ切換器１０に伝達する操作力伝達機構１６は図４に示す変圧器１の部分と同一である。１８は切換開閉器１１を変圧器１より取外し、試験後に変圧器１に取り付ける吊上装置である。
【０００９】
３１は切換開閉器試験容器、３２は試験用切換開閉器容器、３３は試験用操作機構、３４は試験用駆動力伝達機構、３５はシーケンス測定装置、３９は接続ケーブルである。
【００１０】
図７は切換開閉器１１のシーケンス測定を行うシーケンス測定回路図である。シーケンス測定装置３５は測定用電源３６、検出抵抗器３７ａ、３７ｂ、シーケンス波形を収録するオシログラム等で構成された測定エレメント３８ａ、３８ｂで構成されている。３９は切換開閉器１１の端子とシーケンス測定装置３５の間を接続する接続ケーブルであり、切換開閉器接続部１１ａ、１１ｂには接続線３９ａで接続され、中性点側は中性点接続線３９ｎで接続される。
【００１１】
従来の負荷時タップ切換装置１０の切換開閉器１１のシーケンス測定の手順を説明する。まず、対象とする変圧器１を停止し、切換開閉器タンク１２内の絶縁油を抜き取り、切換開閉器１１を取外し、吊上装置１８により切換開閉器１１を吊り上げて切換開閉器試験容器３１に取り付け、切換開閉器１１と試験用操作機構３３は試験用駆動力伝達機構３４で連結し、シーケンス測定装置３５と切換開閉器１１の接続部１１ａ、１１ｂ、１１ｎのそれぞれの間を接続ケーブル３９により図７に示すとおりに結線して測定回路を形成する。
【００１２】
シーケンス測定の奇数タップから偶数タップへの切換に対しては、図７の試験用電源３６を投入し、測定回路に測定電流を通電し、図８（ａ）に示したＡ点から右にシーケンスに示すように電流開閉スイッチ２１、２２、２３、２４を開閉動作させ、測定エレメント３８ａ、３８ｂにより電流波形を検出する。その検出した電流波形の例を図８（ｂ）に示す。図の上段は測定エレメント３８ａの検出電流であり、下段は測定エレメント３８ｂの検出電流である。シーケンス測定装置３５の電源電圧をＥ、限流抵抗器２５ａ、２５ｂの抵抗値をＲ_g 、検出抵抗器３７ａ、３７ｂの抵抗値をＲ_k とすると、Ａ点のタイミングＴ₀ からタイミングＴ₁ の間の電流ｉ₁ 、タイミングＴ₁ からタイミングＴ₃ の間の電流をｉ₂ 、タイミングＴ₂ からＴ₄ の間の電流をｉ₃ およびタイミングＴ₄ からＢ点の間の電流をｉ₄ とすると、それぞれの電流は式（１）〜式（４）のようになる。
ｉ₁ ＝Ｅ／Ｒ_k ・・・・・・・・・・・・・・・・・（式１）
ｉ₂ ＝Ｅ／（Ｒ_g ＋Ｒ_k ）・・・・・・・・・・・・（式２）
ｉ₃ ＝Ｅ／（Ｒ_g ＋Ｒ_k ）・・・・・・・・・・・・（式３）
ｉ₄ ＝Ｅ／Ｒ_k ・・・・・・・・・・・・・・・・・（式４）
また、偶数タップから奇数タップへの切換に対しては奇数タップから偶数タップへの切換の場合の逆方向に図８（ａ）のＢ点から左方向のＡ点の方向のシーケンスで同様に行われる。
【００１３】
【発明が解決しようとする課題】
以上のように変圧器１の負荷時タップ切換器１０の電流開閉スイッチ２１、２２、２３、２４のシーケンス測定は、変圧器１より負荷時タップ切換器１０の切換開閉器１１を取外し、専用の切換開閉器試験容器３１、試験用操作機構３３、試験用駆動力伝達機構３４等で構成されるシーケンス試験装置に取り付けて行い、再度変圧器１に取り付ける方法で行われていたので、切換開閉器容器１２内の絶縁油の抜油作業、切換開閉器１１の取外し作業、試験終了後の取付作業、再注油作業等の繁雑な作業が必要であり、長時間の作業時間と多額の作業費を必要とする問題点があった。また、切換開閉器１１の取付け、取外し時には大気中に露出するので、切換開閉器１１の構成部品の吸湿、塵埃付着等の絶縁信頼性が低下する問題点もあった。
【００１４】
この発明は上記問題点を解決するためになされたものであり、負荷時タップ切換器の切換開閉器を変圧器から取外すことなく切換開閉器のシーケンス測定ができる負荷時タップ切換器の切換開閉器のシーケンス測定方法を提供することを目的とする。
【００１５】
【課題を解決するための手段】
この発明の請求項１記載の負荷時タップ切換器の切換開閉器のシーケンス測定方法は、複数の巻線を備えた負荷時タップ切換変圧器の負荷時タップ切換器が接続された巻線と直列に、直流電流を供給する測定用電源と供給した電流波形を検出する検出手段とを備えたシーケンス測定装置を接続し、該シーケンス測定装置より上記負荷時タップ切換器が接続された巻線に直流の測定電流を供給し、測定電流が安定した状態で切換開閉器を切換動作させ、上記シーケンス測定装置により測定電流の電流波形を検出し、検出した電流波形の変化点を切換開閉器の動作タイミングとする方法である。
【００１６】
この発明の請求項２記載の負荷時タップ切換器の切換開閉器のシーケンス測定方法は、複数の巻線を備えた負荷時タップ切換変圧器の負荷時タップ切換器が接続された巻線と直列に、低周波交流の測定電流を供給する測定用電源と、測定電流の電流波形を検出する検出手段とを備えたシーケンス測定装置を接続し、シーケンス測定装置より負荷時タップ切換器が接続された巻線に低周波交流の測定電流を供給し、測定電流が正または負の半波の間に同期して切換開閉器を切換動作させ、上記シーケンス測定装置により電流波形を検出し、電流波形検出後は電源電圧を徐々に下降して回路スイッチを開路するものとし、上記検出した電流波形の変化点を切換開閉器の動作タイミングとする方法である。
【００１７】
この発明の請求項３記載の負荷時タップ切換器の切換開閉器のシーケンス測定方法は、請求項１または請求項２の方法の負荷時タップ切換器が接続された巻線以外の巻線を短絡接続してシーケンス測定する方法である。
【００１８】
この発明の請求項４記載の負荷時タップ切換器の切換開閉器のシーケンス測定方法は、請求項１または請求項２の方法の形成したシーケンス測定回路のシーケンス測定装置と変圧器の高圧側巻線との間を接続した接続線の高圧線路側に接続した部分を接地してシーケンス測定する方法である。
【００１９】
【発明の実施の形態】
実施の形態１．
実施の形態１は負荷時タップ切換器を備えた変圧器の切換開閉器のシーケンス測定を切換開閉器を取外さないで行う実施の形態である。そのシーケンス測定を行うときの変圧器の状態およびシーケンス測定装置の配置状況を図１に示す。図において、変圧器１は、高圧側巻線２、低圧側巻線３、変圧器タンク４、高圧側巻線２に設けられた複数のタップ５、高圧側ブッシング６ａ、高圧側中性点ブッシング６ｎ、低圧側ブッシング７ａ、７ｂ、負荷時タップ切換器１０の切換開閉器１１、切換開閉器容器１２、接続端子１３ａを備えたタップ選択器１３、タップ５とタップ選択器１３の接続端子１３ａの間を接続する接続リード１４、負荷時タップ切換器１０の操作機構１５、操作機構１５の操作力を負荷時タップ切換器１０に伝達する縦連結軸１６ａ、傘歯車機構１６ｂ、横連結軸１６ｃで構成された操作力伝達機構１６は、図４に示す従来の変圧器の構成と同一である。
【００２０】
４０はシーケンス測定装置、４８は変圧器１の高圧側ブッシング６ａおよび高圧中性点側ブッシング６ｎとシーケンス測定装置４０との間を接続する接続ケーブル、４９は変圧器の低圧側巻線を短絡接続する接続線である。図１の状態は、変圧器１の高圧側巻線２にシーケンス測定装置４０を接続して測定回路を形成している。
【００２１】
図２は図１の構成の測定回路図である。図中の切換開閉器１１は従来の構成の図５（ａ）に示した回路と同一である。シーケンス測定装置４０は、測定電流を供給する測定用電源４１と、検出用可変抵抗器４２と、回路スイッチ４３とが直列に接続され、検出用可変抵抗器４２に並列接続されて検出用可変抵抗器４２の両端電圧を入力して電流波形を検出する電流波形検出手段の測定エレメント４４とで構成され、変圧器に接続される測定ケーブル４８の線間には、シーケンス測定装置４０を試験時の異常電圧から保護するバリスタ４６が接続されている。４５は測定エレメント４４の接地端子であり、変圧器１の高圧側巻線２の線路側に接続する側を接地するように設けられている。測定用電源４１は直流電源が使用される。
【００２２】
負荷時タップ切換器１０の切換開閉器１１のシーケンスを測定する場合は、図２のように測定回路を形成し、検出用可変抵抗器４２の抵抗値を適正値に設定する。シーケンス測定は、回路スイッチ４３を投入し、測定電流が安定するまで持続し、測定電流が安定すると切換開閉器１１を動作させ、シーケンス測定装置４０により電流波形を検出する。測定結果の例を図３に示す。
【００２３】
図３におけるｉ₁ が電流開閉スイッチ２１が閉路しているときの電流であり、Ｔ₁ は電流開閉スイッチ２２が閉路した状態で電流開閉スイッチ２１が開路した時を示し、Ｔ₁ からは限流抵抗２５ａ挿入されて電流ｉ_2tとなって減少し、Ｔ₂ において電流開閉スイッチ２３が閉路して限流抵抗２５ｂが挿入され、限流抵抗２５ａと２５ｂが並列状態になり、電流ｉ_3tとなって増加し、Ｔ₃ において電流開閉スイッチ２２が開路して限流抵抗２５ａが切り離されて電流ｉ_4tとなって再び減少し、Ｔ₄ において電流開閉スイッチ２４が閉路して限流抵抗２５ｂが短絡された後切り離されて電流ｉ_5tとなって増加し、ｉ₁ にほぼ等しいｉ₅ となる波形となる。
【００２４】
図３に示したようなＴ₁ 、Ｔ₂ 、Ｔ₃ 、Ｔ₄ のタイミングが正確に読みとれる電流波形を得るには各タイミング期間における電流が速やかに定常状態になるように回路の時定数を小さくする必要がある。
【００２５】
図２に示す測定回路の変圧器巻線部分の抵抗値をＲｍ、インダクタンスをＬとし、電流開閉スイッチ２２、２３に接続した限流抵抗２５ａ、２５ｂの抵抗値をＲｇ、検出用可変抵抗器４２の抵抗値をＲｓとし、測定用電源４１の電圧をＥとすると、図３の０からタイミングＴ₁ までの間の電流ｉ_1tは（式５）で与えられ、時定数τ₁ は（式６）の通りとなる。時間ｔは回路スイッチ４３を投入してからの経過時間である。
【００２６】
【数１】

【００２７】
タイミングＴ₁ とＴ₂ の間の電流ｉ_2tは（式７）で与えられ、時定数τ₂ は（式８）の通りとなる。
【００２８】
【数２】

【００２９】
タイミングＴ₂ とＴ₃ の間の電流ｉ_3tは（式９）で与えられ、時定数τ₃ は（式１０）の通りとなる。
【００３０】
【数３】

【００３１】
タイミングＴ₃ とＴ₄ の間の電流ｉ_4tは（式１１）で与えられ、時定数τ₄ は（式１２）の通りとなる。
【００３２】
【数４】

【００３３】
タイミングＴ₄ 以後の電流ｉ_5tは（式１３）で与えられ、時定数τ₅ は（式１４）の通りとなる。
【００３４】
【数５】

【００３５】
図３において、電流パターンの変化点Ｔ₁ は電流開閉スイッチ２１の開極タイミングであり、変化点Ｔ₂ は電流開閉スイッチ２３の閉極タイミングであり、変化点Ｔ₃ は電流開閉スイッチ２２の開極タイミングであり、変化点Ｔ₄ は電流開閉スイッチ２４の閉極タイミングを示すものであり、このタイミングＴ₁ 、Ｔ₂ 、Ｔ₃ 、Ｔ₄ を求めることにより切換開閉器１１のシーケンスが測定できる。
【００３６】
以上に示したシーケンス測定方法で精度よくシーケンス測定結果を得るためには、図３のタイミングＴ₁ 、Ｔ₂ 、Ｔ₃ 、Ｔ₄ の変化点が明確に現れることが肝要であり、そのためにはｉ_2t、ｉ_3t、ｉ_4t、ｉ_5tの時定数τ₂ 、τ₃ 、τ₄ 、τ₅ を小さくすることが必要である。
【００３７】
時定数を小さくするには、シーケンス測定回路が接続される変圧器巻線のインダクタンスを小さく、抵抗値を大きくすることである。変圧器巻線のインダクタンスは変圧器鉄心を磁気飽和させることによりインダクタンスは小さな値となる。変圧器鉄心は測定用電源４１に直流を用いることにより簡単に飽和状態にすることができ、変圧器巻線のインダクタンスはほとんど作用しなくなる。
【００３８】
変圧器巻線のインダクタンスを小さくする方法としては、次の方法がある。
ａ．変圧器低圧側巻線３を短絡する方法
ｂ．変圧器の高圧側巻線２と低圧側巻線３のそれぞれの磁化の方向が相殺される方向に接続する方法
ｃ．変圧器の高圧側巻線２と低圧側巻線３のそれぞれの磁化の方向が加算される方向に接続する方法
【００３９】
変圧器の低圧側巻線３を短絡した場合（ａ．の場合）に高圧側から直流電流を流した場合、初期状態の電流変化の間は、高圧側の電流変化量（ｄｉ／ｄｔ）に相当する磁束変化に対応して低圧側にも電流が流れ、鉄心は速やかに飽和状態になり、高圧側から見た抵抗値は、高圧側巻線抵抗と低圧側巻線抵抗に巻数比の２乗を乗じた値が加算された抵抗値となり、変圧器巻線のインダクタンスはほとんど無視できる状態であり、シーケンス測定回路の時定数τは小さな値となって、負荷時タップ切換器の切換開閉器１１の電流開閉スイッチ２１、２２、２３、２４の動作タイミングＴ₁ 、Ｔ₂ 、Ｔ₃ 、Ｔ₄ が明確に検出できる状態となる。
【００４０】
変圧器の高圧側巻線２と低圧側巻線３を直列に接続した場合（ｂ．またはｃ．の場合）は高圧側インダクタンスをＬ₁ 、低圧側インダクタンスをＬ₂ 、相互インダクタンスをＭとすると、高圧側から見たインダクタンスＬは（式１５）のようになる。
Ｌ＝Ｌ₁ ＋Ｌ₂ ±２Ｍ・・・・・・・・・・・・・・（式１５）
±２Ｍの＋は高圧側巻線電流と低圧側巻線電流による磁化力の方向が加算される方向であり、−は高圧側巻線電流と低圧側巻線電流による磁化力が相殺される方向を示すものである。結線の方向が加算される場合あるいは相殺される場合のいずれの場合も直流電流を流した時は短時間で飽和状態になり、巻線のインダクタンスはほとんど影響しなくなる。
【００４１】
実際の変圧器の高圧側巻線２と低圧側巻線３の磁化方向が加わる方向に磁化して例では、高圧側から見たインダクタンスＬが５００Ｈのものが鉄心の飽和状態では０．２Ｈとなり、例えば巻線抵抗Ｒｍ、限流抵抗の抵抗Ｒｇ、検出可変抵抗器の抵抗Ｒｓの合計が１０Ωの場合では時定数τは次のようになる。
τ＝Ｌ／（Ｒｍ＋Ｒｇ＋Ｒｓ）＝０．２／１０＝２０（ｍｓ）
【００４２】
実際の変圧器の負荷時タップ切換器の切換開閉器１１の動作時間は数１０ｍｓであり、切換開閉器１１の切換動作のタイミングＴ₁ 、Ｔ₂ 、Ｔ₃ 、Ｔ₄ が明確に読みとれる図３に示すような状態でシーケンス測定ができるものである。
【００４３】
シーケンス測定時の変圧器巻線の接続は、低圧側を短絡状態にすることが巻線インダクタンスＬを最も小さくできる状態（上記ａ．の方法）であり、次に高圧側巻線と低圧側巻線を磁化方向が相殺する方向に接続する状態（上記ｂ．の方法）であり、直列に接続して磁化方向が加算される方向に接続する状態（上記ｃ．の方法）では相互インダクタンスが加算され大きくなる。しかしながら、変圧器鉄心が飽和状態になっていれば、測定回路の時定数τは小さく、シーケンス測定には上記ａ、ｂ、ｃのいずれの方法であっても支障はない。
【００４４】
以上のように負荷時タップ切換器を備えた変圧器の高圧側巻線２に直流電流を供給して安定した状態で切換開閉器１１を動作させて電流波形を測定し、電流波形の変化点から電流開閉スイッチ２１、２２、２３、２４のシーケンスを検出するシーケンス測定方法によれば、変圧器から負荷時タップ切換器１０の切換開閉器１１取り外すことなくシーケンスを測定することができるようになり、従来のように、切換開閉器容器１２内の絶縁油を抜油して切換開閉器１１を取り外してシーケンス測定し、再取り付けする等の繁雑な作業を行うことなくシーケンス測定ができ、切換開閉器１１を取り外したときの吸湿、塵埃の付着などの問題点がなくなり、短時間で実施できる。
【００４５】
また、測定回路の高圧側巻線２に接続された部分を接地しておくことにより、測定回路への周囲からの誘導の影響をなくすることができる。
【００４６】
また、測定回路の変圧器に接続する部分にバリスタ４６を設けておくことにより測定時の異常電圧から測定回路が保護され、測定者の感電防止にもなる。
【００４７】
実施の形態２．
実施の形態１では、直流の測定電源を用いたが、変圧器に直流を印加すると、測定後の変圧器には磁束が残留する状態となり、電力系統に変圧器が並入されたときの励磁突入電流が大きくなる問題点がある。
【００４８】
実施の形態２は、測定電源を低周波交流としたものである。この場合、測定回路は実施の形態１場合と電源以外は同一とし、電源を例えば数Ｈｚ以下の低周波交流とし、通電電流の方向が正または負の半波の間に切換開閉器１１の動作が完了するように同期してシーケンス測定を行うものである。
【００４９】
電源周波数を数Ｈｚ以下に選択することにより、測定中は測定回路の時定数にはほとんど関係せず直流と同等に測定ができ、測定後に試験電圧を徐々に小さくして終了することにより、変圧器鉄心の残留磁束をなくして試験を終了することができ、並入したときに大きな励磁突入電流が流れることが防止できる。
【００５０】
【発明の効果】
この発明の請求項１記載の負荷時タップ切換器の切換開閉器のシーケンス測定方法は、複数の巻線を備えた負荷時タップ切換変圧器の負荷時タップ切換器が接続された巻線と直列に、直流電流を供給する測定用電源と供給した電流波形を検出する検出手段とを備えたシーケンス測定装置を接続し、シーケンス測定装置より負荷時タップ切換器が接続された巻線に直流の測定電流を供給し、測定電流が安定した状態で切換開閉器を切換動作させ、上記シーケンス測定装置により測定電流の電流波形を検出し、検出した電流波形の変化点を切換開閉器の動作タイミングとする方法であり、変圧器から負荷時タップ切換器の切換開閉器を取外すことなくシーケンスを測定することができるようになり、従来のように切換開閉器を取り外したときの吸湿、塵埃の付着などの問題点が解消され、シーケンス測定が短時間で実施することができる。
【００５１】
この発明の請求項２記載の負荷時タップ切換器の切換開閉器のシーケンス測定方法は、複数の巻線を備えた負荷時タップ切換変圧器の負荷時タップ切換器が接続された巻線と直列に、低周波交流の測定電流を供給する測定用電源と、測定電流の電流波形を検出する検出手段とを備えたシーケンス測定装置を接続し、シーケンス測定装置より負荷時タップ切換器が接続された巻線に低周波交流の測定電流を供給し、測定電流が正または負の半波の間に同期して切換開閉器を切換動作させ、シーケンス測定装置により電流波形を検出し、電流波形検出後は電源電圧を徐々に下降して回路スイッチを開路するものとし、検出した電流波形の変化点を切換開閉器の動作タイミングとする方法であり、直流と同等に測定ができ、測定後に電源電圧を徐々に小さくしていくことにより、変圧器鉄心の残留磁束をなくして試験を終了することができ、変圧器が並入されたときの励磁突入電流を小さくすることができる。
【００５２】
この発明の請求項３記載の負荷時タップ切換器の切換開閉器のシーケンス測定方法は、請求項１または請求項２の方法の負荷時タップ切換器が接続された巻線以外の巻線を短絡接続してシーケンス測定する方法であり、シーケンス測定時の変圧器巻線のインダクタンスが小さくなり、切換開閉器のシーケンスが正確に測定できる。
【００５３】
この発明の請求項４記載の負荷時タップ切換器の切換開閉器のシーケンス測定方法は、請求項１または請求項２の方法の形成したシーケンス測定回路のシーケンス測定装置と変圧器の高圧側巻線との間を接続した接続線の高圧線路側に接続した部分を接地してシーケンス測定する方法であり、測定回路の周囲からの誘導の影響を少なくすることができる。
【図面の簡単な説明】
【図１】この発明による変圧器の負荷時タップ切換器の切換開閉器のシーケンス測定状況を示す図である。
【図２】実施の形態１の負荷時タップ切換器の切換開閉器のシーケンス測定回路図である。
【図３】検出された電流波形の例を示す図である。
【図４】従来の変圧器の負荷時タップ切換器の切換開閉器のシーケンス測定状況を示す図である。
【図５】（ａ）は切換開閉器の電流開閉スイッチの接続図であり、（ｂ）は電流開閉スイッチのシーケンス図である。
【図６】従来の負荷時タップ切換器の切換開閉器を変圧器からの取外し状況図である。
【図７】従来の切換開閉器のシーケンス測定回路図である。
【図８】（ａ）は切換開閉器の電流開閉スイッチのシーケンス図である。（ｂ）は電流開閉スイッチの電流波形図である。
【符号の説明】
１変圧器、２高圧側巻線、３低圧側巻線、４変圧器タンク、
５タップ、６ａ高圧側ブッシング、６ｎ高圧側中性点ブッシング、
７ａ，７ｂ低圧側ブッシング、１０負荷時タップ切換器、
１１切換開閉器、１２切換開閉器容器、１３タップ選択器、
１４接続リード、１５操作機構、１６駆動力伝達機構、１８吊上装置、
２１，２２，２３，２４電流開閉スイッチ、２５ａ，２５ｂ限流抵抗器、
４０シーケンス測定装置、４１測定用電源、４２検出用可変抵抗器、
４３回路スイッチ、４４測定エレメント、４５接地端子、
４６バリスタ、４８接続ケーブル、４９接続線。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sequence measuring method for a switching switch of a load tap changer of a load tap change transformer having a plurality of windings.
[0002]
[Prior art]
A load tap change transformer is usually configured with a plurality of taps provided on the high-voltage side winding and connected to the load tap changer. Tap switching is performed between the connected tap and the tap to be switched. Is bridged with a resistor, and the connection position of the tap is switched.
[0003]
FIG. 4 shows a configuration in the case of a two-resistance switching switch, for example, a load tap changer of the load tap change transformer. In the figure, 1 is a transformer, 2 is a high-voltage side winding, and a plurality of taps 5 are provided on the neutral point side. 3 is a low voltage side winding, 4 is a transformer tank, 5 is a plurality of taps provided on the high voltage side winding 2, 6a is a high voltage side bushing, 6n is a high voltage side neutral point bushing, 7a and 7b are low voltage side bushings It is. Reference numeral 10 denotes an on-load tap changer, which includes a changeover switch 11, a changeover switch container 12 that accommodates the changeover switch 11, and a tap selector 13 that includes a connection terminal 13a. Reference numeral 14 denotes a connection lead for connecting between the tap 5 and the connection terminal 13 a of the tap selector 13. Reference numeral 15 denotes an operating mechanism of the on-

load tap changer

10, and 16 denotes an operating force transmission mechanism that transmits the operating force of the operating mechanism 15 to the on-load tap changer 10. The vertical connection shaft 16 a, the bevel gear mechanism 16 b, and the horizontal connection shaft 16c.
[0004]
FIG. 5A shows a connection diagram of the switching switch 11 of the on-load tap changer 10, and FIG. 5B shows a sequence of the current switching switch built in the switching switch 11. In FIG. 5A,

reference numerals

11a and 11b denote connection parts connected to the tap selector 13, and reference numeral 11n denotes a connection part connected to the neutral point side. 21, 22, 23, 24 are current switching switches built in the

switching switch

11, 25 a is a current limiting resistor connected in series to the

current switching switch

22, and 25 b is a current limiting resistance connected in series to the current switching switch 23. A current switching switch 22 in which a current switching switch 21 and a current limiting resistor 25a are connected in series is connected in parallel and connected to the connecting portion 11a, and a current switching switch 24 and a current limiting resistor 25b are connected in series. The connected current opening / closing switch 23 is connected in parallel and connected to the connecting portion 11b, and the neutral points of the current opening /

closing switches

21, 22, 23, 24 are connected in parallel and connected to the neutral point side connecting portion 11n. ing.
[0005]
The tap 5 selected by the tap selector 13 of the high-voltage side winding 2 of the transformer 1 is connected to the connection portion 11a, the switched tap 5 is connected to the connection portion 11b, and the current switch 21 is closed during operation. The other current opening /

closing switches

22, 23, 24 are open. In this state, if there is a tap switching command, for example, from an odd number tap to an even number tap, the current open /

close switches

21, 22, 23, 24 are opened / closed at the timing shown in FIG. Done. That is, the current open / close switch 21 is set to the timing T ₁ The timing T at which the current opening / closing switch 22 is closed and the current opening / closing switch 22 is opened earlier than the opening at _Three Earlier timing T ₂ The timing T is earlier than the current switching switch 23 is closed and the current switching switch 23 is opened. _Four The current open / close switch 24 is controlled to close. In response to a tap switching command from an even tap to an odd tap, control is performed so that the current open /

close switches

24, 23, 22, 21 are opened / closed in the sequence from point B to point A in FIG.
[0006]
The switching switch 11 of the on-load tap changer 10 generates an arc each time it is switched, resulting in contact consumption. The consumption of each contact causes a change in switching timing (hereinafter referred to as a switching switch sequence). When the consumption becomes severe, the current remaining amount of the current switching switches 21, 22, 23, 24 is lost, and a long arc is generated. In addition to the problem that the current open / close switch 21 and the current open / close switch 23 are simultaneously connected by an arc to cause a short circuit between the taps, it is described in 3.3.1 of JEC 2230-1988, (Reference 2). Thus, the current switching switches 21 and 24 that cut off only the normal load current according to the load factor of the transformer, and the bridge current and half of the load current that flow between the taps when the

current switching switches

22 and 23 are simultaneously closed. Increases the interruption consumption difference between the current on /

off switches

22 and 23 that cut off only the current superimposed or the difference current. Timing T shown in cross spacing or FIG 5 (b) of the opening and closing timings of 24 ₁ , T ₂ , T _Three , T _Four Will change.
[0007]
For this reason, the switching interval or sequence of the current switching switch of the tap changer during loading is an important factor related to the success or failure of the current switching in the switching switch. It is an indispensable matter to grasp.
[0008]
In the conventional sequence measurement of the switching switch 11 of the on-load tap switch 10, the transformer 1 is stopped, the switching switch 11 of the on-load tap switch 10 is taken out, and the taken out switching switch 11 is used as a test tank. The installation was performed by a dedicated test device. The situation is shown in FIG. In the figure, the portion of the transformer 1 has the configuration shown in FIG. 4, and a tap 5 for voltage adjustment provided in the high-voltage side winding 2, the low-voltage side winding 3, the transformer tank 4, and the high-voltage side winding 2. A high pressure side bushing 6a, a high pressure side neutral point bushing 6n, a low pressure side bushing 7a, 7b, a load tap changer 10, a changeover switch 11, a changeover switch container 12, and a tap selector 13 having a connection terminal 13a. Connection lead 14 connecting between the tap 5 and the connection terminal 13a of the tap selector 13, the operating mechanism 15 of the on-load tap changer 10, and the operating force transmission for transmitting the operating force of the operating mechanism 15 to the on-load tap changer 10. The mechanism 16 is the same as that of the transformer 1 shown in FIG. Reference numeral 18 denotes a lifting device for removing the switching switch 11 from the transformer 1 and attaching it to the transformer 1 after the test.
[0009]
Reference numeral 31 is a switching switch test container, 32 is a test switching switch container, 33 is a test operation mechanism, 34 is a test driving force transmission mechanism, 35 is a sequence measuring device, and 39 is a connection cable.
[0010]
FIG. 7 is a sequence measurement circuit diagram for performing sequence measurement of the switching switch 11. The sequence measurement device 35 includes a measurement power source 36,

detection resistors

37a and 37b, and

measurement elements

38a and 38b each including an oscillogram for recording a sequence waveform. Reference numeral 39 denotes a connection cable for connecting the terminal of the switching switch 11 and the sequence measuring device 35. The switching

switch connection portions

11a and 11b are connected by a connection line 39a, and the neutral point side is a neutral point connection line. 39n is connected.
[0011]
A sequence measurement procedure of the switching switch 11 of the conventional on-load tap switching device 10 will be described. First, the target transformer 1 is stopped, the insulating oil in the switching switch tank 12 is drained, the switching switch 11 is removed, and the switching switch 11 is lifted by the lifting device 18 to the switching switch test container 31. The mounting / switching switch 11 and the test operation mechanism 33 are connected by a test driving force transmission mechanism 34, and a connection cable 39 connects between the sequence measuring device 35 and the

connection portions

11 a, 11 b, 11 n of the switching switch 11. Connection is made as shown in FIG. 7 to form a measurement circuit.
[0012]
For switching from odd-numbered taps to even-numbered taps in sequence measurement, the test power source 36 in FIG. 7 is turned on, a measurement current is supplied to the measurement circuit, and the sequence from the point A shown in FIG. The current open /

close switches

21, 22, 23, and 24 are opened and closed as shown in FIG. 5 and current waveforms are detected by the

measurement elements

38a and 38b. An example of the detected current waveform is shown in FIG. The upper part of the figure is the detection current of the measurement element 38a, and the lower part is the detection current of the measurement element 38b. The power supply voltage of the sequence measuring device 35 is E, and the resistance values of the current limiting

resistors

25a and 25b are R. _g The resistance value of the

detection resistors

37a and 37b is R _k Then, the timing T at point A ₀ To timing T ₁ Current i between ₁ , Timing T ₁ To timing T _Three The current between ₂ , Timing T ₂ To T _Four The current between _Three And timing T _Four To the current between point B and i _Four Then, each electric current becomes like Formula (1)-Formula (4).
i ₁ = E / R _k ・・・・・・・・・・・・・・・・ (Formula 1)
i ₂ = E / (R _g + R _k ) (Equation 2)
i _Three = E / (R _g + R _k ) (Equation 3)
i _Four = E / R _k ..... (Formula 4)
Further, for switching from the even tap to the odd tap, the sequence is similarly performed in the sequence from the B point to the left A point in FIG. 8A in the reverse direction when switching from the odd tap to the even tap. Is called.
[0013]
[Problems to be solved by the invention]
As described above, the sequence measurement of the

current switch

21, 22, 23, 24 of the on-load tap changer 10 of the transformer 1 is performed by removing the change-over switch 11 of the on-load tap changer 10 from the transformer 1. Since the switching switch test container 31, the test operation mechanism 33, the test driving force transmission mechanism 34, etc. are attached to the sequence test apparatus and then attached to the transformer 1 again, the switching switch is used. It requires complicated work such as draining the insulating oil in the container 12, removing the switching switch 11, mounting after the test, re-lubricating, etc., and requires a long working time and a large work cost. There was a problem. In addition, since the switch is exposed to the atmosphere when the switch 11 is attached or removed, there is a problem that the insulation reliability such as moisture absorption and dust adhesion of the components of the switch 11 is lowered.
[0014]
The present invention has been made to solve the above-described problems, and is a switching switch for a load tap changer capable of measuring the sequence of the switching switch without removing the load change switch from the transformer. It is an object to provide a sequence measurement method.
[0015]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a method for measuring a sequence of a switching switch of a load tap changer in series with a winding connected to a load tap changer of a load tap change transformer having a plurality of windings. A sequence measuring device having a measuring power source for supplying a direct current and a detecting means for detecting the supplied current waveform, and connecting the direct current to the winding connected to the on-load tap changer from the sequence measuring device. The measurement switch is operated in a state where the measurement current is stable, the current waveform of the measurement current is detected by the sequence measuring device, and the change point of the detected current waveform is determined as the switching switch operation timing. It is a method.
[0016]
According to a second aspect of the present invention, there is provided a sequence measuring method for a switching switch of a load tap changer in series with a winding connected to a load tap changer of a load tap change transformer having a plurality of windings. Connected to a sequence measuring device having a measuring power source for supplying a low-frequency AC measuring current and a detecting means for detecting a current waveform of the measuring current, and a load tap changer was connected from the sequence measuring device. Supply low-frequency AC measurement current to the winding, and switch the switching switch in synchronization between the positive and negative half-waves of the measurement current, detect the current waveform with the above sequence measurement device, and detect the current waveform After that, the power supply voltage is gradually lowered to open the circuit switch, and the change point of the detected current waveform is used as the operation timing of the switching switch.
[0017]
According to a third aspect of the present invention, there is provided a method for measuring a sequence of a switching switch of a load tap changer, wherein the windings other than the winding connected to the load tap changer of the method of

claim

1 or 2 are short-circuited. This is a method of connecting and measuring a sequence.
[0018]
According to a fourth aspect of the present invention, there is provided a sequence measuring method for a switching switch of a tap changer at the time of loading. The sequence measuring device of the sequence measuring circuit formed by the method of the first or second aspect and the high-voltage side winding of the transformer This is a method of performing sequence measurement by grounding a portion connected to the high-voltage line side of the connection line connected between the two.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
The first embodiment is an embodiment in which the sequence measurement of the switching switch of the transformer provided with the on-load tap switching device is performed without removing the switching switch. FIG. 1 shows the state of the transformer and the arrangement state of the sequence measurement device when performing the sequence measurement. In the figure, a transformer 1 includes a high voltage side winding 2, a low voltage side winding 3, a transformer tank 4, a plurality of taps 5 provided on the high voltage side winding 2, a high voltage side bushing 6a, and a high voltage side neutral point bushing. 6n, low

pressure side bushings

7a, 7b, switching switch 11 of on-load tap switch 10, switching switch container 12, tap selector 13 having connection terminal 13a, connection terminal 13a of tap 5 and tap selector 13 A connection lead 14 that connects between them, an operating mechanism 15 of the on-load tap changer 10, a vertical connection shaft 16 a that transmits the operating force of the operation mechanism 15 to the on-load tap changer 10, a bevel gear mechanism 16 b, and a horizontal connection shaft 16 c. The constructed operating force transmission mechanism 16 has the same configuration as that of the conventional transformer shown in FIG.
[0020]
40 is a sequence measuring device, 48 is a connection cable for connecting the high voltage side bushing 6a and high voltage neutral point side bushing 6n of the transformer 1 and the sequence measuring device 40, 49 is a short circuit connection of the low voltage side winding of the transformer It is a connecting line. In the state of FIG. 1, a sequence measurement device 40 is connected to the high-voltage side winding 2 of the transformer 1 to form a measurement circuit.
[0021]
FIG. 2 is a measurement circuit diagram of the configuration of FIG. The switching switch 11 in the figure is the same as the circuit shown in FIG. The sequence measurement device 40 includes a measurement power supply 41 for supplying a measurement current, a detection variable resistor 42, and a circuit switch 43 connected in series, and connected in parallel to the detection variable resistor 42 so as to detect the variable resistance. And a measuring element 44 of current waveform detecting means for detecting a current waveform by inputting a voltage at both ends of the measuring device 42, and a sequence measuring device 40 is connected between the measuring cables 48 connected to the transformer during the test. A varistor 46 that protects against abnormal voltage is connected. Reference numeral 45 denotes a ground terminal of the measurement element 44, which is provided so as to ground the side connected to the line side of the high-voltage side winding 2 of the transformer 1. The measurement power supply 41 is a DC power supply.
[0022]
When measuring the sequence of the switching switch 11 of the on-load tap changer 10, a measurement circuit is formed as shown in FIG. 2, and the resistance value of the detection variable resistor 42 is set to an appropriate value. The sequence measurement is continued until the circuit switch 43 is turned on and the measurement current is stabilized. When the measurement current is stabilized, the switching switch 11 is operated, and the sequence measurement device 40 detects the current waveform. An example of the measurement result is shown in FIG.
[0023]
I in FIG. ₁ Is the current when the current switch 21 is closed, and T ₁ Indicates when the current switch 21 is opened while the current switch 22 is closed, and T ₁ Current limiting resistor 25a is inserted and current i _2t Decreased and T ₂ Current closing switch 23 is closed, current limiting resistor 25b is inserted, current limiting

resistors

25a and 25b are in parallel, and current i _3t Increased and T _Three The current opening / closing switch 22 is opened and the current limiting resistor 25a is disconnected, and the current i _4t It decreases again and T _Four In FIG. 5, the current opening / closing switch 24 is closed and the current limiting resistor 25b is short-circuited, and then the current i _5t And increase i ₁ I approximately equal to _Five It becomes the waveform which becomes.
[0024]
T as shown in FIG. ₁ , T ₂ , T _Three , T _Four In order to obtain a current waveform in which the timing can be accurately read, it is necessary to reduce the time constant of the circuit so that the current in each timing period quickly reaches a steady state.
[0025]
The resistance value of the transformer winding portion of the measurement circuit shown in FIG. 2 is Rm, the inductance is L, the resistance values of the current limiting

resistors

25a and 25b connected to the current switching switches 22 and 23 are Rg, and the detection variable resistor 42 3 is Rs, and the voltage of the measurement power supply 41 is E. ₁ Current i until _1t Is given by (Equation 5) and the time constant τ ₁ Is as in (Equation 6). Time t is an elapsed time since the circuit switch 43 was turned on.
[0026]
[Expression 1]

[0027]
Timing T ₁ And T ₂ Current i between _2t Is given by (Equation 7) and the time constant τ ₂ Is as in (Equation 8).
[0028]
[Expression 2]

[0029]
Timing T ₂ And T _Three Current i between _3t Is given by (Equation 9) and the time constant τ _Three Is as in (Equation 10).
[0030]
[Equation 3]

[0031]
Timing T _Three And T _Four Current i between _4t Is given by (Equation 11) and the time constant τ _Four Is as in (Equation 12).
[0032]
[Expression 4]

[0033]
Timing T _Four Subsequent current i _5t Is given by (Equation 13) and the time constant τ _Five Is as in (Equation 14).
[0034]
[Equation 5]

[0035]
In FIG. 3, the change point T of the current pattern ₁ Is the opening timing of the current open / close switch 21, and the change point T ₂ Is the closing timing of the current open / close switch 23, and the change point T _Three Is the opening timing of the current open / close switch 22, and the change point T _Four Indicates the closing timing of the current opening / closing switch 24, and this timing T ₁ , T ₂ , T _Three , T _Four Is obtained, the sequence of the switching switch 11 can be measured.
[0036]
In order to obtain a sequence measurement result with the above sequence measurement method with high accuracy, the timing T in FIG. ₁ , T ₂ , T _Three , T _Four It is important that the point of change clearly appears. _2t , I _3t , I _4t , I _5t Time constant τ ₂ , Τ _Three , Τ _Four , Τ _Five Must be reduced.
[0037]
In order to reduce the time constant, the inductance of the transformer winding to which the sequence measurement circuit is connected is reduced and the resistance value is increased. The inductance of the transformer winding becomes a small value by magnetically saturating the transformer core. The transformer core can be easily saturated by using direct current for the measurement power supply 41, and the inductance of the transformer winding hardly acts.
[0038]
There are the following methods for reducing the inductance of the transformer winding.
a. Method of short-circuiting the transformer low-voltage side winding 3
b. Method of connecting in a direction in which the magnetization directions of the high-voltage side winding 2 and the low-voltage side winding 3 of the transformer cancel each other
c. Method of connecting in a direction in which the respective magnetization directions of the high voltage side winding 2 and the low voltage side winding 3 of the transformer are added
[0039]
When a DC current is passed from the high voltage side when the low voltage side winding 3 of the transformer is short-circuited (in the case of a.), The current change amount (di / dt) on the high voltage side during the current change in the initial state. Corresponding to the corresponding magnetic flux change, a current also flows on the low voltage side, the iron core quickly becomes saturated, and the resistance value seen from the high voltage side is 2 turns ratio between the high voltage side winding resistance and the low voltage side winding resistance. The value multiplied by the power is the added resistance value, and the inductance of the transformer winding is almost negligible. 11 operation timing T of current open /

close switches

21, 22, 23, 24 ₁ , T ₂ , T _Three , T _Four Can be clearly detected.
[0040]
When the high-voltage side winding 2 and the low-voltage side winding 3 of the transformer are connected in series (in the case of b. Or c.), The high-voltage side inductance is set to L. ₁ , Low side inductance is L ₂ When the mutual inductance is M, the inductance L viewed from the high voltage side is as shown in (Equation 15).
L = L ₁ + L ₂ ± 2M (Equation 15)
+ Of ± 2M is a direction in which the direction of the magnetizing force due to the high-voltage side winding current and the low-voltage side winding current is added. Is shown. In both cases where the directions of the connections are added or cancelled, when a direct current is passed, saturation occurs in a short time and the winding inductance has little effect.
[0041]
In the example, the high-voltage side winding 2 and the low-voltage side winding 3 of the actual transformer are magnetized in the direction in which the magnetization direction is applied. In the example, the inductance L as viewed from the high voltage side is 0.2H when the iron core is saturated. For example, when the total of the winding resistance Rm, the resistance Rg of the current limiting resistance, and the resistance Rs of the detection variable resistor is 10Ω, the time constant τ is as follows.
τ = L / (Rm + Rg + Rs) = 0.2 / 10 = 20 (ms)
[0042]
The operation time of the switching switch 11 of the actual tap load switch of the transformer is several tens of ms, and the switching operation timing T of the switching switch 11 is T. ₁ , T ₂ , T _Three , T _Four Can be measured in a state as shown in FIG.
[0043]
The connection of the transformer winding at the time of sequence measurement is a state where the winding inductance L can be minimized by making the low-voltage side short-circuited (method a), and then the high-voltage side winding and the low-voltage side winding. In the state where the lines are connected in the direction in which the magnetization direction cancels out (method b), the mutual inductance is added in the state where the lines are connected in series and connected in the direction in which the magnetization directions are added (method c). It gets bigger. However, if the transformer core is saturated, the time constant τ of the measurement circuit is small, and any of the above methods a, b, and c is not problematic for sequence measurement.
[0044]
As described above, a DC current is supplied to the high-voltage side winding 2 of the transformer having the on-load tap changer, and the change-over switch 11 is operated in a stable state to measure the current waveform. According to the sequence measuring method for detecting the sequence of the

current switch

21, 22, 23, 24, the sequence can be measured without removing the switching switch 11 of the on-load tap switch 10 from the transformer. As in the prior art, the insulating oil in the switching switch container 12 is drained, the switching switch 11 is removed, the sequence measurement is performed, and the sequence measurement can be performed without performing complicated operations such as reattachment. Problems such as moisture absorption and dust adhesion when 11 is removed can be eliminated and can be carried out in a short time.
[0045]
In addition, by grounding the portion connected to the high-voltage side winding 2 of the measurement circuit, the influence of the induction from the surroundings on the measurement circuit can be eliminated.
[0046]
Further, by providing the varistor 46 in the portion of the measurement circuit that is connected to the transformer, the measurement circuit is protected from abnormal voltage during measurement, and it also prevents the measurer from electric shock.
[0047]
Embodiment 2. FIG.
In the first embodiment, a direct current measurement power supply is used. However, when direct current is applied to the transformer, magnetic flux remains in the transformer after measurement, and excitation occurs when the transformer is placed in parallel in the power system. There is a problem that the inrush current increases.
[0048]
In the second embodiment, the measurement power source is a low-frequency alternating current. In this case, the measurement circuit is the same as in the first embodiment except for the power source, the power source is a low-frequency alternating current of, for example, several Hz or less, and the operation of the switching switch 11 is performed while the direction of the energizing current is positive or negative half-wave. The sequence measurement is performed synchronously so as to be completed.
[0049]
By selecting a power supply frequency of several Hz or less, the measurement can be performed in the same way as direct current with little relation to the time constant of the measurement circuit. The test can be completed by eliminating the residual magnetic flux in the iron core, and a large exciting inrush current can be prevented from flowing when the test is performed in parallel.
[0050]
【The invention's effect】
According to a first aspect of the present invention, there is provided a method for measuring a sequence of a switching switch of a load tap changer in series with a winding connected to a load tap changer of a load tap change transformer having a plurality of windings. Connected to a sequence measuring device equipped with a measuring power source for supplying a direct current and a detecting means for detecting the supplied current waveform, and direct current is measured from the sequence measuring device to a winding connected with a load tap changer. Supply the current, switch the switching switch in a state where the measured current is stable, detect the current waveform of the measured current by the sequence measuring device, and use the detected change point of the current waveform as the operation timing of the switching switch This method makes it possible to measure the sequence without removing the switching switch of the on-load tap changer from the transformer, and the suction when the switching switch is removed as in the prior art. , Problems such as adhesion of dust is eliminated, it is possible to sequence measurement is carried out in a short time.
[0051]
According to a second aspect of the present invention, there is provided a sequence measuring method for a switching switch of a load tap changer in series with a winding connected to a load tap changer of a load tap change transformer having a plurality of windings. Connected to a sequence measuring device having a measuring power source for supplying a low-frequency AC measuring current and a detecting means for detecting a current waveform of the measuring current, and a load tap changer was connected from the sequence measuring device. Supply low-frequency AC measurement current to the winding, switch the switching switch in synchronization with the positive or negative half-wave, and detect the current waveform with the sequence measurement device. Is a method in which the power supply voltage is gradually lowered to open the circuit switch, and the change point of the detected current waveform is used as the operation timing of the switching switch. gradually By gradually reduced, it is possible to end the test by eliminating the residual magnetic flux of the transformer core, a transformer can be made smaller magnetizing inrush current when NamiIri.
[0052]
According to a third aspect of the present invention, there is provided a method for measuring a sequence of a switching switch of a load tap changer, wherein the windings other than the winding connected to the load tap changer of the method of

claim

1 or 2 are short-circuited. It is a method of connecting and measuring the sequence, and the inductance of the transformer winding at the time of sequence measurement is reduced, and the sequence of the switching switch can be measured accurately.
[0053]
According to a fourth aspect of the present invention, there is provided a sequence measuring method for a switching switch of a tap changer at the time of loading. The sequence measuring device of the sequence measuring circuit formed by the method of the first or second aspect and the high-voltage side winding of the transformer This is a method of performing sequence measurement by grounding a portion connected to the high-voltage line side of the connection line connected between the two and the influence of induction from the periphery of the measurement circuit can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a sequence measurement situation of a switching switch of a load tap changer of a transformer according to the present invention.
FIG. 2 is a sequence measurement circuit diagram of the switching switch of the on-load tap changer according to the first embodiment.
FIG. 3 is a diagram illustrating an example of a detected current waveform.
FIG. 4 is a diagram showing a sequence measurement situation of a switching switch of a conventional tap changer in a transformer.
5A is a connection diagram of current switching switches of a switching switch, and FIG. 5B is a sequence diagram of current switching switches.
FIG. 6 is a diagram illustrating a state in which the switching switch of the conventional load tap changer is removed from the transformer.
FIG. 7 is a sequence measurement circuit diagram of a conventional switching switch.
FIG. 8A is a sequence diagram of a current switching switch of a switching switch. (B) is a current waveform diagram of the current switching switch.
[Explanation of symbols]
1 Transformer, 2 High voltage side winding, 3 Low voltage side winding, 4 Transformer tank,
5 taps, 6a high pressure side bushing, 6n high pressure side neutral point bushing,
7a, 7b Low pressure side bushing, 10 Load tap changer,
11 switching switch, 12 switching switch container, 13 tap selector,
14 connection lead, 15 operation mechanism, 16 driving force transmission mechanism, 18 lifting device,
21, 22, 23, 24 Current switch, 25a, 25b Current limiting resistor,
40 sequence measurement device, 41 power supply for measurement, 42 variable resistor for detection,
43 Circuit switch, 44 Measuring element, 45 Ground terminal,
46 Varistor, 48 connection cable, 49 connection line.

Claims

A measuring power supply for supplying a direct current and a detecting means for detecting the supplied current waveform are provided in series with the winding connected to the on-load tap changer of the on-load tap change transformer having a plurality of windings. Connecting the sequence measuring device, supplying a DC measuring current from the sequence measuring device to the winding connected to the on-load tap changer, and switching the switching switch in a state where the measuring current is stable. A method for measuring a sequence of a switching switch of an on-load tap changer, wherein a current waveform of a measurement current is detected by a sequence measuring device, and a change point of the detected current waveform is used as an operation timing of the switching switch.

A measurement power supply for supplying low-frequency AC measurement current in series with the winding connected to the load tap changer of the load tap change transformer with multiple windings, and detecting the current waveform of the measurement current A sequence measuring device including a detecting means for supplying a low-frequency alternating current to the winding connected to the load tap changer from the sequence measuring device. The switching switch is switched in synchronization with the wave, and the current waveform is detected by the sequence measuring device. After the current waveform is detected, the power supply voltage is gradually lowered to open the circuit switch. A method for measuring a sequence of a switching switch of a load-type tap switching switch in which a change point of a current waveform is an operation timing of the switching switch.

3. A sequence measuring method for a switching switch of a load tap changer according to claim 1, wherein a sequence other than the winding connected to the load tap changer is short-circuited to perform sequence measurement. .

The sequence measurement is performed by grounding a portion connected to the high voltage line side of the connection line connecting the sequence measurement device of the formed sequence measurement circuit and the high voltage side winding of the transformer. The sequence measuring method of the switching switch of the on-load tap changer according to claim 2.