JP4662322B2

JP4662322B2 - Method for measuring voltage using gas transmitted light and method for estimating surface contamination

Info

Publication number: JP4662322B2
Application number: JP2001289699A
Authority: JP
Inventors: 紹大高橋; 達希岡本; 邦彦日高
Original assignee: Central Research Institute of Electric Power Industry
Current assignee: Central Research Institute of Electric Power Industry
Priority date: 2001-09-21
Filing date: 2001-09-21
Publication date: 2011-03-30
Anticipated expiration: 2021-09-21
Also published as: JP2003098198A

Description

【０００１】
【発明の属する技術分野】
本発明は、気体透過光を用いた電圧測定方法及び表面汚損の推定方法に関する。さらに詳述すると、本発明は、気体の電気光学カー効果を利用した電圧測定方法及び表面汚損の推定方法に関するものである。
【０００２】
【従来の技術】
例えばガス絶縁機器等の機器類の電圧をモニタするために、機器類の端子に電圧用の計測器を接続する。特に高圧の機器類の電圧をモニタする場合には計器用変圧器（ＶＴ）等の計測器を使用する。この場合、機器類の外部に高圧端子を取り出し、この高圧端子に計器用変圧器を接続する。
【０００３】
また、大気を絶縁材とするブッシングや碍子等の絶縁部材は屋外で使用するものであり、表面が汚損する。絶縁部材の表面の汚損は、その部分の電位分担（その部分にかかる電圧）を減少させることになり、その分だけ他の部分の電位分担を増加させることになるので、絶縁状態の維持を困難にする虞がある。このため、絶縁部材の表面汚損を定期的に観測して絶縁破壊を未然に防ぐことが好ましい。
【０００４】
【発明が解決しようとする課題】
しかしながら、上述の計器用変圧器を使用して機器類の電圧をモニタする方法では、機器類の外部に高圧端子を取り出し、この高圧端子に計器用変圧器を接続する必要があるため、計器用変圧器の絶縁に大きな離隔距離や専用のガス絶縁タンクが必要となる。このため、システムの大型化を招き、設備コストの低減を困難にしている。
【０００５】
一方、ブッシングや碍子等の絶縁部材については、その表面にセンサ類を取り付けると絶縁破壊が生じる虞があるのでセンサ類を取り付けて表面の電圧を測定し、これに基づいて表面汚損を推定することは困難である。また、特に碍子は高所に設置されるものであるため、表面を直接目視することは困難である。これらのため、ブッシングや碍子等の絶縁部材の表面汚損を推定する方法の開発が要請されている。
【０００６】
本発明は、機器類の外部に取り出す高圧端子を不要にして設備の小型化が可能な電圧測定方法を提供することを目的とする。また、本発明は、ブッシングや碍子等の絶縁部材等について、その表面汚損を推定可能な方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
本発明者らは、気体の電気光学カー効果（電気的カー効果）について鋭意研究を行った結果、従来考えられていたように気体の電気光学カー効果は一部の限られた気体にのみ発現するものではなく、気体一般に発現するものであることを見出すと共に、気体のカー定数は非常に小さいものではあるが、気体の電気光学力効果を利用して電界の測定を行えることを知見した。
【０００８】
本発明は、かかる知見に基づくものであって、請求項１記載の発明は、気体中に設置された導体としてのガス絶縁機器の高電圧導体又はブッシングの口出線、気体中に設置された固体絶縁材としてのブッシング又は碍子のいずれかを測定対象とし、前記測定対象の周囲に存在する前記気体中に電界が発生している場合の電圧測定方法において、気体の電界影響領域に検出光を透過させる光路を決定し、測定対象の電圧と光路の透過光の偏光状態との対応関係を予め求めておき、光路に検出光を透過させて、その透過光の偏光状態から前記対応関係を利用して測定対象の電圧を求めるものである。
【０００９】
電圧がかけられた測定対象の周囲には電界が発生する。そして、気体の電界影響領域（電界の影響を受ける領域）では、測定対象の電圧に応じて誘電率異方性（屈折率異方性）が変化する。この電界影響領域に光を透過させると、透過光は電界影響領域の誘電率異方性に応じた偏光状態となる。したがって、測定対象の電圧と透過光の偏光状態とは一定の対応関係を示すことになり、この対応関係を利用することで実測した透過光の偏光状態に基づいて、測定対象の電圧を求めることができる。
【００１０】
また、請求項２記載の気体透過光を用いた電圧測定方法は、ガス絶縁機器の高電圧導体又はブッシングの口出線を測定対象とし、測定対象に既知の値の試験電圧をかけながら光路に検出光を透過させて測定対象にかけた電圧と透過光の偏光状態との対応関係を予め求めておくものである。
【００１１】
導体である測定対象に電圧がかかると、その測定対象の周囲に電界が発生する。そして、気体の電界影響領域では、測定対象の電圧に応じて誘電率異方性（屈折率異方性）が変化する。この電界影響領域に光を透過させると、透過光は電界影響領域の誘電率異方性に応じた偏光状態となる。したがって、測定対象にかけた電圧と透過光の偏光状態とは一定の対応関係を示すことになり、この対応関係を利用することで実測した透過光の偏光状態に基づいて、測定対象の電圧を求めることができる。測定対象にかけた電圧と透過光の偏光状態との関係は、測定対象に既知の値の試験電圧をかけた実測を繰り返すことで求められる。
【００１２】
また、請求項３記載の気体透過光を用いた電圧測定方法は、ガス絶縁機器の高電圧導体を測定対象とし、気体は測定対象を収容するタンク内に充填されており、検出光の光源はタンクの外に設けられており、タンクに設けた窓から検出光を気体に向けて照射するものである。
【００１３】
ガス絶縁機器では、高電圧となる導体を絶縁する気体即ちガス絶縁体がタンク内に納められている。このため、高電圧導体の電圧を測定するために遮光体であるタンクの外に光源と光検出器を設置すると、ガス絶縁体に検出光を入射させることができない。したがって、遮光体に窓を形成することで、光源からガス絶縁体に検出光を入射させることができ、また、ガス絶縁体の電界影響領域を透過した透過光を光検出器に向けて出射させることができる。
【００１４】
また、請求項４記載の気体透過光を用いた電圧測定方法は、窓の電位をタンクの電位と等しくするものである。したがって、例えばガス絶縁機器では遮光体としてのガスタンクの電位を接地電位に落とすことで窓の部分の電位も接地電位に落とすことができる。
【００１５】
また、請求項５記載の気体透過光を用いた電圧測定方法は、検出光を反射させて電界影響領域を複数回通過するように光路を決定するものである。
【００１６】
したがって、光路に照射された検出光は電界影響領域を複数回通過する。電界影響領域を通過する度に検出光（透過光）は偏光状態を変化させるので、偏光状態を大きく変化させることができる。即ち、透過光の偏波面変化は誘電率異方性のある媒質を通過している間積分されるため、電界影響領域を透過する距離を長くすることで透過光の偏波面変化を大きくすることができる。
【００１７】
また、請求項６記載の気体透過光を用いた電圧測定方法は、検出光を変調して光路に透過させると共に、光路を透過した透過光を同期検波し、同期検波後の透過光の偏光状態から上記対応関係を利用して測定対象の電圧を求めるものである。
【００１８】
気体の揺らぎや検出光の光源の出力揺らぎ等は測定のノイズとなる。光路を透過した透過光の偏光状態の中から変調の周波数成分だけを抽出することで、気体の揺らぎや光源の揺らぎ等のノイズ要因を除去して電圧測定を行うことができる。
【００１９】
さらに、請求項７記載の発明は、気体中に設置されたブッシング又は碍子を推定対象とし、推定対象の周囲に存在する気体中に電界が発生している場合の表面汚損の推定方法において、気体の電界影響領域に検出光を透過させる光路を決定し、光路に検出光を透過させてその透過光の偏光状態を観測し、当該偏光状態の変化に基づいて推定対象の表面汚損を推定するものである。
【００２０】
気体の電界影響領域（電界の影響を受ける領域）では、電界を発生させる電圧の値に応じた誘電率異方性（屈折率異方性）となる。したがって、推定対象の表面に汚損が堆積することで推定対象表面の電圧が変化すると、電界影響領域の誘電率異方性も変化する。電界影響領域に光を透過させると、その透過光の偏光状態は電界影響領域の誘電率異方性に応じたものになるので、誘電率異方性の変化に基づいて推定対象表面の電圧の変化、即ち推定対象表面の汚損の有無や堆積状態を推定することができる。
【００２１】
また、請求項８記載の気体透過光を用いた表面汚損の推定方法は、検出光を反射させて電界影響領域を複数回通過するように光路を決定するものである。
【００２２】
したがって、光路に照射された検出光は電界影響領域を複数回通過する。電界影響領域を通過する度に検出光（透過光）は偏光状態を変化させるので、偏光状態を大きく変化させることができる。即ち、透過光の偏波面変化は誘電率異方性のある媒質を通過している間積分されるため、電界影響領域を透過する距離を長くすることで透過光の偏波面変化を大きくすることができる。
【００２３】
また、請求項９記載の気体透過光を用いた表面汚損の推定方法は、検出光を変調して光路に透過させると共に、光路を透過した透過光を同期検波し、同期検波後の透過光の偏光状態を観測するものである。
【００２４】
気体の揺らぎや検出光の光源の出力揺らぎ等は測定のノイズとなる。光路を透過した透過光の偏光状態の中から変調の周波数成分だけを抽出することで、気体の揺らぎや光源の揺らぎ等のノイズ要因を除去して表面汚損を推定することができる。
【００２５】
【発明の実施の形態】
以下、本発明の構成を図面に示す最良の形態に基づいて詳細に説明する。図１に本発明を適用した気体透過光を用いた電圧測定方法の実施形態の一例を示す。また、この電圧測定方法をガス絶縁機器に適用した例を図２及び図３に示す。
【００２６】
この電圧測定方法は、気体１１中に設置された導体としてのガス絶縁機器の高電圧導体又はブッシングの口出線、気体１１中に設置された固体絶縁材としてのブッシング又は碍子のいずれかを測定対象（以下、部材１２という）とし、部材１２の周囲に存在する気体１１中に電界が発生している場合の電圧を測定する方法であって、気体１１の電界影響領域１３に検出光１４を透過させる光路１５を決定し（ステップＳ１）、部材１２の電圧と光路１５の透過光の偏光状態との対応関係（関数）を予め求めておき（ステップＳ２）、光路１５に検出光１４を透過させて（ステップＳ３）、その透過光の偏光状態から前記対応関係を利用して部材１２の電圧を求める（ステップＳ４）ものである。
【００２７】
図２及び図３に示すガス絶縁機器１６の高電圧導体の電圧を測定する例では、電圧を測定する対象の部材１２がガス絶縁機器１６の高電圧導体（以下、高電圧導体１２という）である。また、部材１２の電圧と光路１５の透過光の偏光状態との対応関係として、高電圧導体１２に既知の値の試験電圧をかけながら光路１５に検出光１４を透過させて高電圧導体１２にかけた電圧と透過光の偏光状態との対応関係を求めている。
【００２８】
ガス絶縁機器１６のタンク１７内には気体１１としてのガス絶縁体（以下、ガス絶縁体１１という）が充填されており、このガス絶縁体１１によって高電圧導体１２を絶縁している。高電圧導体１２の周囲には電界が発生する。したがって、電界内にガス絶縁体１１が存在することになる。
【００２９】
まず、ガス絶縁体１１の電界影響領域（電界の影響を受ける領域）１３に検出光１４を透過させる光路１５を決定する（ステップＳ１）。この光路１５上に検出光１４を伝搬させることでガス絶縁体１１の電界影響領域１３中を透過させる。
【００３０】
次に、この光路１５における高電圧導体１２にかけた電圧と透過光の偏光状態との対応関係を求める（ステップＳ２）。高電圧導体１２にかけた電圧と透過光の偏光状態とが一定の対応関係を示すのは以下の理由からである。
【００３１】
高電圧導体１２の周囲には電界が発生するので、電界影響領域１３ではガス絶縁体１１は電気光学カー効果（電気的カー効果）により誘電率異方性体となる。その屈折率は高電圧導体１２にかけた電圧の二乗に比例して変化する。
【００３２】
ここで、本発明者等は、気体の電気光学カー効果を利用して電界の測定を行えることを実験により確認した。
【００３３】
実験は、観測用窓付き高圧密閉容器に被測定対象気体を加圧密閉すると共に、密閉容器内の平行平板電極に直流高電圧を印加し、平行平板電極間にレーザ光を透過させることによってを行った。気体のカー効果による複屈折のため、電極間を透過したレーザ光には、電極間の電界Ｅの二乗に比例した偏波間位相差Γが生じる。この偏波間位相差Γを数式１に示す。
【数１】
Γ＝２πＢｌＥ^２（Ｂはカー定数、ｌは光路長）
気体のカー定数は極めて小さいため、カー効果による位相差の検出にはＳ／Ｎ比を向上させる必要がある。そこで、光学ミラーを用いて、光路ｌを長くし信号自体を大きくするとともに、入射レーザ光（Ｈｅ−Ｎｅレーザ、波長６３２．８ｎｍ）を、音響光学変調素子（Photo Elestic Modulator）により５０ｋＨｚで位相変調し、Ｏ／Ｅ変換器検出信号を、ロックインアンプで同期検波した。
【００３４】
図８に、０．４９５ＭＰａ、ＣＯ_２下の測定結果例を示す。図上部に印加電界（印加電圧を電極間距離２０ｍｍで割ったもの）の二乗を、図下部に偏波間位相差測定結果を示す。電界を約２０秒かけて５．２［ＭＶ／ｍ］まで、さらに７秒かけて６．２［ＭＶ／ｍ］までと二段階に上昇させた後、電源をオフにし回路時定数に応じて下降させている。
【００３５】
図８より、検出位相差は、印加電界の二乗に良く追従していることがわかる。
【００３６】
表１に、各種ガス、圧力下でのカー定数測定結果を示す。カー定数は圧力依存性があるので、各数値とも０．１ＭＰａあたりに規格化した値である。
【表１】

【００３７】
そこで誘電率異方性を示すガス絶縁体１１に光を透過させると、その偏光状態はガス絶縁体１１の誘電率異方性に応じて変化する。即ち、高電圧導体１２の電圧に応じてガス絶縁体１１の誘電率異方性が定まり、ガス絶縁体１１の誘電率異方性に応じて透過光の偏光状態が定まるので、高電圧導体１２にかける電圧とガス絶縁体１１の透過光の偏光状態との間には一定の対応関係が成立することになる。
【００３８】
高電圧導体１２に既知の値の試験電圧をかけた状態でガス絶縁体１１の電界影響領域１３に検出光１４を透過させ、その透過光の偏光状態を測定する。例えば、検光子によって透過光の特定方向成分を取り出し、その光強度を測定する。そして、高電圧導体１２にかける試験電圧を変えて同様の測定を繰り返し行う。このように試験電圧を変えた測定を繰り返し行うことで、高電圧導体１２にかかる電圧と電界影響領域１３を透過した透過光の偏光状態との対応関係を求めることができる。
【００３９】
同じガス絶縁機器１６であっても光路１５が異なると、高電圧導体１２にかける電圧と透過光の偏光状態との対応関係は変化する。したがって、実際に電圧測定を行う光路１５について、高電圧導体１２にかける電圧と透過光の偏光状態との対応関係を求めておく。
【００４０】
このようにして高電圧導体１２にかけた電圧と透過光の偏光状態との対応関係を求めた後、光路１５に検出光１４を透過させ（ステップＳ３）、その透過光の偏光状態から前記対応関係を利用して高電圧導体１２の電圧を求める（ステップＳ４）。即ち、実測した透過光の偏光状態を前記対応関係に当てはめることで、その偏光状態に対応する電圧を導くことができ、この電圧が高電圧導体１２の電圧となる。
【００４１】
検出光１４として、ガス絶縁体１１を透過し得る波長の光を使用する。タンク１７は検出光１４を透過させない遮光体であるので、タンク１７の光路１５上の部位に検出光１４を透過させる窓を形成する。本実施形態では、タンク１７の光路１５上の部位に、検出光１４を入射させる入射窓１８と、電界影響領域１３を透過した透過光を出射させる出射窓１９を形成している。
【００４２】
窓１８，１９は、タンク１７に孔１７ａをあけ、この孔１７ａを検出光１４が透過し得る材料の栓２０で塞ぐことで構成される。栓２０は例えばガラスによって形成される。栓２０の外面には例えば導電性コートが施されており、窓１８，１９の電位をタンク１７の電位と等しくしている。タンク１７の電位は接地電位に落とされており、窓１８，１９に導電性コートを施していない場合には栓２０の部分に電圧が発生する虞がある。そのため、栓２０の外面に導電性コートを施すことで栓２０の電位を接地電位に落とし、電圧の発生を防いで絶縁上の安全性をより高めている。導電性コートとして、例えばＩＴＯ（酸化インジウムスズ）膜を形成する。本実施形態では、ＩＴＯ膜を形成したガラス片を栓２０として孔１７ａに嵌め込んで気密に接着し窓１８，１９を形成する。なお、窓１８，１９の大きさは検出光１４が通過できる限度で可能な限り小さくすることが好ましい。窓１８，１９を小さくすることで、絶縁上の安全をより図ることができる。
【００４３】
例えば図２及び図３に示すように、入射窓１８には検出光１４の光源２１が取り付けられている。また、出射窓１９には検出器２２が取り付けられている。検出器２２は検光子と受光器より構成されている。受光器の出力は例えば図示しない電圧記録装置に供給される。タンク１７は接地電位に落とされており、タンク１７の外周面に光源２１や検出器２２の取り付けを可能にしている。
【００４４】
光源２１から検出光１４を入射窓１８に向けて照射すると、この検出光１４はガス絶縁体１１の電界影響領域１３を通って出射窓１９から検出器２２の検光子に入射する。
【００４５】
電界影響領域１３ではガス絶縁体１１は誘電率に異方性を有しているので、ガス絶縁体１１に入射した検出光１４は、直ちに誘電率の大きい方向と小さい方向（互いに直交）の直線偏波に分かれ、それぞれの屈折率（速度）で光路１５を伝搬する。その結果、図４に示すように、誘電率の大きい方向と小さい方向の直線偏波に位相差が生じ、これらを合成して考えると、ガス絶縁体１１に入射する前の状態と比べて偏波面が変形する。したがって、ガス絶縁体１１の電界影響領域１３を透過した後の透過光の特定方向成分（たとえば図４のｘ軸及びｙ軸に対して４５度方向の成分）に注目すると、この特定方向成分の光強度はガス絶縁体１１の誘電率異方性の大きさに依存することになる。この特定方向成分の光を検出器２２の電界方向から定まる適切な方向の検光子によって取り出し受光器に入射させると、光強度に応じた信号、即ち電界影響領域１３の誘電率異方性の大きさに対応した信号を得ることができる。屈折率異方性に分布がある物質の場合には、この現象が平均化されて現れる。
【００４６】
そして、既知の値の試験電圧を高電圧導体１２にかけて透過光の特定方向成分の光強度を測定し、かかる測定を試験電圧を変えて複数回おこなう。複数回の測定結果に基づいて高電圧導体１２にかかる電圧値と透過光の特定方向成分の光強度との関係式をフィッティングする（ステップＳ２）。例えば、数式２のような関係式がフィッティングされる。
【数２】
光強度＝Ａ×ｃｏｓ（Ｂ×電圧の二乗＋Ｃ）
ただし、Ａ，Ｂ，Ｃはガス絶縁機器１６ごとに設定する関係式毎に定める係数
この様な関係式を求めた後、稼働中のガス絶縁機器１６の高電圧導体１２の電圧測定をおこなう。透過光の特定方向成分の光強度を計測する（ステップＳ３）ことで、上記関係式から高電圧導体１２の電圧を求めることができる（ステップＳ４）。
【００４７】
実際には、ガス絶縁機器１６の高電圧導体１２には商用周波数、例えば５０Ｈｚ又は６０Ｈｚの周波数の交流電流が流れていることからその周波数で透過光の特定方向成分の光強度は変化する。光源２１から検出光１４を連続して照射することで、透過光の特定方向成分の光強度を連続して計測することができ、高電圧導体１２の電圧を連続してモニタすることができる。
【００４８】
このように、本発明では、高電圧導体１２を絶縁するガス絶縁体１１を利用して高電圧導体１２の電圧値を測定することができる。このため、電圧測定に必要な設備がコンパクトになり、設備コストを低減することができる。
【００４９】
また、高電圧導体１２を絶縁するガス絶縁体１１の電界影響領域１３に検出光１４を透過させることで高電圧導体１２の電圧を測定できるので、簡単に電圧測定を行うことができる。
【００５０】
また、実際に測定を行う光路１５を決定し、この光路１５について上記対応関係を求めて電圧測定を行うので、光路１５の選択の自由度が高く、いろいろな場所に適用することができる。即ち、同一のガス絶縁機器１６であってもいろいろな場所に適用することができ、また、ガス絶縁機器１６の高電圧導体１２以外の部材についても適切な場所を選択して適用することができる。これらのため、汎用性に優れ、使い勝手の良い電圧測定方法を提供することができる。
【００５１】
なお、上述の説明では、ガス絶縁機器１６の高電圧導体１２の電圧を測定する場合を例にしていたが、これに限るものではないことは勿論である。例えばブッシングの口出線等の電圧を測定するのに適用しても良い。
【００５２】
また、電圧測定の対象となる部材１２としては必ずしも導体である必要はなく、例えば、ブッシングや碍子等の固体絶縁材やその他の部材であっても良い。例えばブッシングの碍管の表面の電位分担を測定することも可能である。
【００５３】
図５に、部材１２としてのブッシング（以下、ブッシング１２という）の表面の電位分担（その部分にかかる電圧）を測定する例を示す。例えば図５中符号２３で示す部分の電位分担を測定する場合には、その部分２３の周囲の電界影響領域１３に検出光１４を通過させるようにする。
【００５４】
この場合にも、気体１１の電界影響領域１３に検出光１４を透過させる光路１５を決定し（ステップＳ１）、部分２３の電圧と光路１４の透過光の偏光状態との対応関係を予め求めておき（ステップＳ２）、光路１５に検出光１４を透過させて（ステップＳ３）、その透過光の偏光状態から前記対応関係を利用して部分２３の電圧を求める（ステップＳ４）ことができる。
【００５５】
ブッシング１２の表面の電位分担は、ブッシング１２の形状や誘電率に応じて決まるものである。したがって、ブッシング１２の図示しない口出線の電圧に基づいて部分２３の電位分担を算出することができる。即ち、この場合には、ステップＳ２において、口出線に既知の値の試験電圧をかけながら光路１５に検出光１４を透過させ、口出線の試験電圧に基づいて算出した部分２３の電位分担と透過光の偏光状態との対応関係を求めれば良い。
【００５６】
なお、図５の実施形態では、光源２１から出射されて電界影響領域１３を通過した検出光１４をミラー２４によって反射し、もう一度、電界影響領域１３を通過させて検出器２２に入射させるようにしている。即ち、検出光１４が電界影響領域１３を２回通過するように光路１５を決定している。このように、検出光１４が電界影響領域１３を２回通過することで検出器２２に入射する気体透過光の偏光状態をより大きく変化させることができ、検出の感度が向上してより正確に電圧測定を行うことができる。
【００５７】
また、検出光１４が電界影響領域１３を通過する回数は２回に限るものではなく、３回以上、電界影響領域１３を通過するようにしても良いことは勿論である。検出光１４を電界影響領域１３に何度も通過させることで検出光１４が誘電率異方性のある領域を通過する距離を長くすることができ、透過光の偏光状態をより大きく変化させることができる。なお、検出光１４を例えば３往復させて誘電率異方性のある領域、即ち電界影響領域１３を６回通過させ、検出の感度を６倍向上させる場合の概念を図６に示す。なお、このように検出光１４を反射させて電界影響領域１３を複数回通過させることで検出の感度を向上させることができる点は、図５に示す実施形態以外の実施形態でも同様である。
【００５８】
なお、図１のステップＳ２において対応関係を求める場合に、複数の対応関係、即ち電界影響領域１３の温度（気体密度）を少しずつ変化させた対応関係を求めておき、実測を行う（ステップＳ３）ときの実際の電界影響領域１３の温度（気体密度）に応じて適切な対応関係を選択し、選択した対応関係を利用して電圧値を求める（ステップＳ４）ようにしても良い。
【００５９】
次に、本発明を適用した気体透過光を用いた表面汚損の推定方法の実施形態の一例について説明する。この表面汚損の推定方法は、上述した電圧測定方法と同一の原理に基づいて表面汚損を推定するものである。例えば、屋外に設置されているブッシングや碍子等の表面汚損を推定することができる。図５及び図７に基づいて具体的に説明する。
【００６０】
いま、図５のブッシング１２が屋外に設置されているとする。このブッシング１２の表面には汚損物質が付着する。汚損物質には塩分など、水に溶けた場合に導電性を示すものがある。ブッシング１２の表面に付着した汚損物質が雨や湿気等で濡れると、その部分が導電性を持つことになるので電位分担（その部分にかかる電圧）が小さくなり、その分だけ他の部分の電位分担が大きくなる。このため、汚損物質の堆積を放置しておくと、ついには絶縁が保てなくなって放電が起きる虞がある。本発明では、ブッシング１２の表面汚損を推定することができるので、ブッシング１２の交換時期を知ることができる。
【００６１】
本発明の表面汚損の推定方法は、気体１１中に設置されたブッシング又は碍子を推定対象（以下、部材１２という）とし、推定対象の周囲に存在する気体１１中に電界が発生している場合の表面汚損の推定方法であって、気体１１の電界影響領域１３に検出光１４を透過させる光路１５を決定し（ステップＳ５）、光路１５に検出光１４を透過させてその透過光の偏光状態を観測し（ステップＳ６）、当該偏光状態の変化に基づいて部材１２の表面汚損を推定する（ステップＳ７）ものである。
【００６２】
表面汚損の堆積に伴いその部分２３の電位分担が変化するので、その部分２３の周囲の電界も変化し、その周囲の電界影響領域１３の誘電率異方性も変化する。電界影響領域１３の誘電率異方性の変化に応じて光路１５の透過光の偏光状態も変化するので、結局、光路１５の透過光の偏光状態をモニタすることで、その偏光状態の変化に基づいて当該部分２３の表面汚損を推定することができる。また、汚損の堆積量の増加に伴い透過光の偏光状態の変化量も増加するので、表面汚損の有無だけではなく、表面汚損の堆積状態も推定することができる。
【００６３】
なお、ブッシング１２の表面の複数箇所について電位分担を測定するようにしても良い。測定箇所が１箇所でもブッシング１２の表面汚損を推定することはできるが、複数箇所について電位分担を測定し表面汚損を推定することで、どの部分に汚損物質がたくさん堆積しているかについての評価を行うことが可能になる。また、測定箇所が１箇所の場合には、測定値の変化が表面汚損に起因したものであるのか、又は口出線（ブッシング１２内を通っている導体）の印加電圧の変化に起因したものであるのかの判断が困難なときがある。これに対し、複数箇所について測定を行うことで、かかる判断が容易になる。
【００６４】
本発明は、例えば鉄塔等に取り付けられた碍子等の絶縁部材の表面汚損を測定するのにも適している。特に碍子は鉄塔等の高所に配置されるものであるため、その表面汚損の検出が困難であるが、本発明では碍子から離れた位置に光源２１と検出器２２を設置することが可能であり、高所に配置される碍子についても表面汚損を簡単に推定することができる。つまり、地上にレーザ光線等の光源２１と検出器２２を設置し、碍子の近傍に設置したミラー２４によって検出光１４を反射させることで、地上から鉄塔上の碍子の表面にかかる電位分担を測定することができる。このため、碍子の表面汚損の堆積状況を簡単にモニタすることができ、設備の保守上非常に有効である。
【００６５】
また、ブッシングや碍子等の部材１２に割れ等の破損が生じた場合には、その部分の電位分担が減少し、その周囲の電界影響領域１３の誘電率異方性が変化する。したがって、光路１５の透過光の偏光状態も変化するので、透過光の偏光状態の変化に基づいて部材１２の割れ等の破損を検出することができる。
【００６６】
なお、上述の各実施形態は本発明の好適な形態の一例ではあるがこれに限定されるものではなく本発明の要旨を逸脱しない範囲において種々変形実施可能である。例えば、検出光１４を変調して光路１５に透過させると共に、光路１５の電界影響領域１３を透過した透過光を同期検波し、同期検波後の透過光の偏光状態から前記対応関係を利用して部材１２の電圧を求めるようにしても良く、あるいは、同期検波後の透過光の偏光状態を観測することで部材１２の表面汚損を推定するようにしても良い。温度変化や、短絡電流などの急峻な電流変化に起因する電磁力等により、気体１１が揺らぐことがある。また、光源２１の出力に揺らぎが生じることがある。気体１１の揺動や光源２１の揺らぎは、測定出力である透過光の特定方向成分の光強度に対しノイズ要因になるので、測定出力にノイズが含まれることになる。本発明では、検出光１４にある周波数で位相変調をかけ、それを光検出器２２で検出した後、例えばロックインアンプ等のフィルタ装置を用いて同期検波、即ち特定の周波数成分だけ取り出すことで、先にかけた変調の周波数成分だけを取り出すことができる。これにより、周波数が異なる気体１１の揺らぎや光源２１の揺らぎ等のノイズ要因を除去することができ、Ｓ／Ｎ（信号／雑音）比を向上させることができる。
【００６７】
【発明の効果】
以上説明したように請求項１記載の気体透過光を用いた電圧測定方法では、気体の電界影響領域に検出光を透過させる光路を決定し、測定対象の電圧と光路の透過光の偏光状態との対応関係を予め求めておき、光路に検出光を透過させて、その透過光の偏光状態から前記対応関係を利用して測定対象の電圧を求めるようにしているので、もともと、機器の絶縁材料として使用されているものを測定器の一部として利用することから、計器用変圧器を接続して電圧測定を行う場合のように絶縁の為に大掛かりな設備が不要になり、コンパクトな構造によって測定対象にかかる電圧を測定することができる。このため、設備コストを低減することができる。また、光路の選択の自由度が高く、汎用性に優れ使い勝手の良い電圧測定方法を提供することができる。さらに、ブッシングや碍子等の絶縁部材の表面にかかる電圧を測定することができる。
【００６８】
また、請求項２記載の気体透過光を用いた電圧測定方法では、ガス絶縁機器の高電圧導体又はブッシングの口出線を測定対象とし、測定対象に既知の値の試験電圧をかけながら光路に検出光を透過させて測定対象にかけた電圧と透過光の偏光状態との対応関係を予め求めておくようにしている。
【００６９】
また、請求項３記載の気体透過光を用いた電圧測定方法では、窓を利用して光路を確保して電圧測定を行うことができる。
【００７０】
また、請求項４記載の気体透過光を用いた電圧測定方法では、窓の電位をタンクの電位と等しくしているので、例えばガス絶縁機器のガスタンクのような遮光体に窓を形成した場合、ガスタンクの電位を接地電位に落とすことで窓の電位も接地電位に落とすことができ、絶縁上より安全である。
【００７１】
また、請求項５記載の気体透過光を用いた電圧測定方法では、検出光を反射させて電界影響領域を複数回通過するように光路を決定しているので、透過光の偏光状態を大きく変化させることができ、測定の感度を向上させることができる。
【００７２】
さらに、請求項６記載の気体透過光を用いた電圧測定方法では、検出光を変調して光路に透過させると共に、光路を透過した透過光を同期検波し、同期検波後の透過光の偏光状態から前記対応関係を利用して測定対象の電圧を求めるようにしているので、測定出力から気体の揺らぎや光源の揺らぎなどのノイズ要因を除去することができ、測定出力のＳ／Ｎ（信号／雑音）比を向上させることができ、測定の精度を向上させることができる。
【００７３】
また、請求項７記載の気体透過光を用いた表面汚損の測定方法では、気体の電界影響領域に検出光を透過させる光路を決定し、光路に検出光を透過させてその透過光の偏光状態を観測し、当該偏光状態の変化に基づいて推定対象の表面汚損を推定するようにしているので、例えば高所に設置された碍子や地上からの観察では隠れてしまうような推定対象の部分の表面汚損を推定することができる。また、簡単な設備で推定対象の表面汚損を推定することができる。
【００７４】
また、請求項８記載の気体透過光を用いた表面汚損の推定方法では、検出光を反射させて電界影響領域を複数回通過するように光路を決定しているので、透過光の偏光状態を大きく変化させることができ、偏光状態の観測の感度を向上させることができる。
【００７５】
また、請求項９記載の気体透過光を用いた表面汚損の推定方法では、検出光を変調して光路に透過させると共に、光路を透過した透過光を同期検波し、同期検波後の透過光の偏光状態を観測するようにしているので、測定出力から気体の揺らぎや光源の揺らぎなどのノイズ要因を除去することができ、測定出力のＳ／Ｎ（信号／雑音）比を向上させることができ、偏光状態の観測の精度を向上させることができる。
【図面の簡単な説明】
【図１】本発明に係る気体透過光を用いた電圧測定方法の実施形態の一例を示すフローチャートである。
【図２】本発明をガス絶縁機器に適用した場合の斜視図である。
【図３】本発明をガス絶縁機器に適用した場合の断面図である。
【図４】誘電率異方性を持つ気体によって検出光が偏光される様子を概念的に示す説明図である。
【図５】本発明をブッシングに適用した場合の概念図である。
【図６】検出光を反射させて電界影響領域を複数回通過するように光路を決定する概念図である。
【図７】本発明に係る気体透過光を用いた表面汚損の推定方法の実施形態の一例を示すフローチャートである。
【図８】印加電界とＣＯ_２の偏波間位相差測定結果を示す図である。
【符号の説明】
１１気体
１２部材
１３気体の電界影響領域
１４検出光
１５光路
１７タンク（遮光体）
１８入射窓
１９出射窓[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a voltage measurement method using gas transmitted light and a method for estimating surface contamination. More specifically, the present invention relates to a voltage measurement method and a surface contamination estimation method using a gas electro-optic Kerr effect.
[0002]
[Prior art]
For example, in order to monitor the voltage of equipment such as gas insulation equipment, a voltage measuring instrument is connected to the equipment terminal. In particular, when monitoring the voltage of high voltage equipment, a measuring instrument such as an instrument transformer (VT) is used. In this case, a high voltage terminal is taken out from the equipment, and an instrument transformer is connected to the high voltage terminal.
[0003]
Insulating members such as bushings and insulators that use the atmosphere as an insulating material are used outdoors, and the surface is soiled. Contamination of the surface of the insulating member reduces the potential sharing of that part (voltage applied to that part), and increases the potential sharing of other parts accordingly, so it is difficult to maintain the insulation state. There is a risk. For this reason, it is preferable to regularly observe the surface contamination of the insulating member to prevent dielectric breakdown.
[0004]
[Problems to be solved by the invention]
However, in the method of monitoring the voltage of equipment using the above-described instrument transformer, it is necessary to take out the high voltage terminal outside the equipment and connect the instrument transformer to this high voltage terminal. Large isolation distances and dedicated gas insulation tanks are required for transformer insulation. For this reason, the size of the system is increased, making it difficult to reduce the equipment cost.
[0005]
On the other hand, for insulating members such as bushings and insulators, there is a risk that dielectric breakdown may occur if sensors are attached to the surface, so sensors should be attached and the surface voltage measured, and surface contamination estimated based on this It is difficult. In particular, since the insulator is installed at a high place, it is difficult to directly observe the surface. For these reasons, there is a demand for the development of a method for estimating the surface contamination of insulating members such as bushings and insulators.
[0006]
An object of the present invention is to provide a voltage measurement method that can reduce the size of equipment without requiring a high-voltage terminal to be taken out of the equipment. Another object of the present invention is to provide a method capable of estimating the surface contamination of insulating members such as bushings and insulators.
[0007]
[Means for Solving the Problems]
As a result of intensive studies on the electro-optic Kerr effect (electric Kerr effect) of the gas, the present inventors have revealed that the electro-optic Kerr effect of gas is manifested only in some limited gases. In addition to finding out that the gas is generally expressed in gas, the Kerr constant of the gas is very small, but it has been found that the electric field can be measured using the electro-optic force effect of the gas.
[0008]
The present invention is based on such knowledge, and the invention according to claim 1 The measurement object is either a high-voltage conductor or bushing lead wire of a gas insulation device as a conductor installed in a gas, or a bushing or insulator as a solid insulation material installed in a gas. An electric field is generated in the gas present in Case Power of In the pressure measurement method, determine the optical path through which the detection light is transmitted to the electric field affected region of the gas, Measurement target The correspondence relationship between the voltage of the light and the polarization state of the transmitted light in the optical path is obtained in advance, the detection light is transmitted through the optical path, and the correspondence relationship is utilized from the polarization state of the transmitted light. Measurement target Is obtained.
[0009]
Voltage was applied Measurement target An electric field is generated around the. And in the electric field affected area of gas (area affected by electric field) Measurement target The dielectric anisotropy (refractive index anisotropy) changes according to the voltage of. When light is transmitted through the electric field affected region, the transmitted light is polarized according to the dielectric anisotropy of the electric field affected region. Therefore, Measurement target Based on the polarization state of the transmitted light actually measured by using this correspondence, Measurement target Can be obtained.
[0010]
Moreover, the voltage measuring method using the gas transmitted light according to claim 2 is: Measure high voltage conductors or bushing lead wires of gas insulation equipment. , Measurement target Let the detection light pass through the optical path while applying a known test voltage to Measurement target The correspondence relationship between the voltage applied to and the polarization state of the transmitted light is obtained in advance.
[0011]
conductor Measurement target When voltage is applied to Measurement target An electric field is generated around And in the electric field effect region of gas, Measurement target The dielectric anisotropy (refractive index anisotropy) changes according to the voltage of. When light is transmitted through the electric field affected region, the transmitted light is polarized according to the dielectric anisotropy of the electric field affected region. Therefore, Measurement target The voltage applied to and the polarization state of the transmitted light show a certain correspondence relationship, and based on the polarization state of the transmitted light actually measured by using this correspondence relationship, Measurement target Can be obtained. Measurement target The relationship between the applied voltage and the polarization state of transmitted light is Measurement target Is obtained by repeating the actual measurement with a known test voltage applied.
[0012]
Moreover, the voltage measuring method using the gas transmitted light according to claim 3 is: Measuring high voltage conductors of gas insulated equipment Gas Measurement target The light source of the detection light is provided outside the tank, and the detection light is emitted toward the gas from a window provided in the tank.
[0013]
Ga In a gas insulating device, a gas, that is, a gas insulator, which insulates a conductor having a high voltage is stored in a tank. For this reason, if a light source and a light detector are installed outside the tank, which is a light shielding body, in order to measure the voltage of the high voltage conductor, the detection light cannot be incident on the gas insulator. Therefore, by forming a window in the light shield, detection light can be incident from the light source to the gas insulator, and transmitted light that has passed through the electric field effect region of the gas insulator is emitted toward the photodetector. be able to.
[0014]
The voltage measurement method using gas-transmitted light according to claim 4 is characterized in that the potential of the window is set. tank It is made equal to the potential. Therefore, for example, in a gas insulating device, the potential of the window portion can be lowered to the ground potential by dropping the potential of the gas tank as the light shield to the ground potential.
[0015]
According to a fifth aspect of the present invention, there is provided a voltage measuring method using gas transmitted light, wherein the optical path is determined so as to reflect the detection light and pass through the electric field affected region a plurality of times.
[0016]
Therefore, the detection light applied to the optical path passes through the electric field affected region a plurality of times. Since the detection light (transmitted light) changes the polarization state every time it passes through the electric field effect region, the polarization state can be changed greatly. In other words, since the polarization plane change of the transmitted light is integrated while passing through a medium with dielectric anisotropy, the polarization plane change of the transmitted light is increased by increasing the distance that passes through the electric field affected region. Can do.
[0017]
The voltage measurement method using the gas transmitted light according to claim 6 modulates the detection light and transmits the modulated light to the optical path, synchronously detects the transmitted light transmitted through the optical path, and the polarization state of the transmitted light after the synchronous detection. From the above correspondence Measurement target Is obtained.
[0018]
Gas fluctuations, output fluctuations of the light source of detection light, and the like become measurement noise. By extracting only the frequency component of the modulation from the polarization state of the transmitted light that has passed through the optical path, it is possible to remove the noise factor such as gas fluctuation and light source fluctuation and perform voltage measurement.
[0019]
Furthermore, the invention of claim 7 A bushing or insulator installed in the gas is the target of estimation, and an electric field is generated in the gas around the target of estimation. Case Table In the estimation method of surface contamination, the optical path through which the detection light is transmitted to the gas electric field affected region is determined, the detection light is transmitted through the optical path, the polarization state of the transmitted light is observed, and the change in the polarization state is determined. Estimation target This is to estimate the surface contamination.
[0020]
In the gas electric field effect region (region affected by the electric field), dielectric anisotropy (refractive index anisotropy) corresponding to the value of the voltage generating the electric field is obtained. Therefore, Estimation target By fouling on the surface of Estimation target When the voltage on the surface changes, the dielectric anisotropy of the electric field affected region also changes. When light is transmitted through the field-affected region, the polarization state of the transmitted light depends on the dielectric anisotropy of the field-affected region. Estimation target Change in surface voltage, ie Estimation target It is possible to estimate the presence / absence of surface contamination and the accumulation state.
[0021]
According to another aspect of the present invention, there is provided a method for estimating surface contamination using gas-transmitted light, wherein the optical path is determined so as to reflect the detection light and pass through the electric field affected region a plurality of times.
[0022]
Therefore, the detection light applied to the optical path passes through the electric field affected region a plurality of times. Since the detection light (transmitted light) changes the polarization state every time it passes through the electric field effect region, the polarization state can be changed greatly. In other words, since the polarization plane change of the transmitted light is integrated while passing through a medium with dielectric anisotropy, the polarization plane change of the transmitted light is increased by increasing the distance that passes through the electric field affected region. Can do.
[0023]
The method of estimating surface contamination using gas transmitted light according to claim 9 modulates the detection light and transmits the modulated light to the optical path, synchronously detects the transmitted light transmitted through the optical path, and transmits the transmitted light after the synchronous detection. It observes the polarization state.
[0024]
Gas fluctuation, output fluctuation of the light source of detection light, and the like become measurement noise. By extracting only the frequency component of the modulation from the polarization state of the transmitted light that has passed through the optical path, it is possible to estimate the surface contamination by removing noise factors such as gas fluctuations and light source fluctuations.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail based on the best mode shown in the drawings. FIG. 1 shows an example of an embodiment of a voltage measuring method using gas transmitted light to which the present invention is applied. Moreover, the example which applied this voltage measuring method to the gas insulation apparatus is shown in FIG.2 and FIG.3.
[0026]
This voltage measurement method is Either a high-voltage conductor or bushing lead wire of a gas insulation device as a conductor installed in the gas 11 or a bushing or insulator as a solid insulation material installed in the gas 11 (hereinafter referred to as member 12) And when an electric field is generated in the gas 11 existing around the member 12 In this method for measuring voltage, an optical path 15 for transmitting the detection light 14 to the electric field affected region 13 of the gas 11 is determined (step S1), and the correspondence between the voltage of the member 12 and the polarization state of the transmitted light of the optical path 15 is determined. A (function) is obtained in advance (step S2), the detection light 14 is transmitted through the optical path 15 (step S3), and the voltage of the member 12 is obtained from the polarization state of the transmitted light using the corresponding relationship (step). S4).
[0027]
In the example of measuring the voltage of the high voltage conductor of the gas insulation device 16 shown in FIGS. 2 and 3, the member 12 whose voltage is to be measured is the high voltage conductor of the gas insulation device 16 (hereinafter referred to as the high voltage conductor 12). is there. Further, as a correspondence relationship between the voltage of the member 12 and the polarization state of the transmitted light of the optical path 15, the detection light 14 is transmitted through the optical path 15 and applied to the high-voltage conductor 12 while applying a known test voltage to the high-voltage conductor 12. The correspondence between the measured voltage and the polarization state of the transmitted light is obtained.
[0028]
The tank 17 of the gas insulation device 16 is filled with a gas insulator as the gas 11 (hereinafter referred to as the gas insulator 11), and the high voltage conductor 12 is insulated by the gas insulator 11. An electric field is generated around the high voltage conductor 12. Therefore, the gas insulator 11 exists in the electric field.
[0029]
First, an optical path 15 through which the detection light 14 is transmitted to the electric field affected region (region affected by the electric field) 13 of the gas insulator 11 is determined (step S1). By propagating the detection light 14 on the optical path 15, the detection light 14 is transmitted through the electric field affected region 13 of the gas insulator 11.
[0030]
Next, the correspondence between the voltage applied to the high voltage conductor 12 in the optical path 15 and the polarization state of the transmitted light is obtained (step S2). The reason why the voltage applied to the high voltage conductor 12 and the polarization state of the transmitted light show a certain correspondence is as follows.
[0031]
Since an electric field is generated around the high voltage conductor 12, the gas insulator 11 becomes a dielectric anisotropy due to the electro-optic Kerr effect (electric Kerr effect) in the electric field affected region 13. The refractive index changes in proportion to the square of the voltage applied to the high voltage conductor 12.
[0032]
Here, the present inventors have confirmed through experiments that the electric field can be measured using the electro-optic Kerr effect of gas.
[0033]
In the experiment, the gas to be measured was pressurized and sealed in a high-pressure sealed container with an observation window, a high DC voltage was applied to the parallel plate electrodes in the sealed container, and laser light was transmitted between the parallel plate electrodes. went. Due to the birefringence due to the gas Kerr effect, the laser beam transmitted between the electrodes has a polarization phase difference Γ proportional to the square of the electric field E between the electrodes. This inter-polarization phase difference Γ is shown in Equation 1.
[Expression 1]
Γ = 2πBlE ² (B is the Kerr constant, l is the optical path length)
Since the Kerr constant of gas is extremely small, it is necessary to improve the S / N ratio in order to detect a phase difference due to the Kerr effect. Therefore, using an optical mirror, the optical path l is lengthened and the signal itself is increased, and incident laser light (He-Ne laser, wavelength 632.8 nm) is phase-modulated at 50 kHz by an acousto-optic modulator (Photo Elestic Modulator). The O / E converter detection signal was synchronously detected by a lock-in amplifier.
[0034]
In FIG. 8, 0.495 MPa, CO ₂ An example of the measurement result is shown below. The square of the applied electric field (applied voltage divided by the electrode distance of 20 mm) is shown in the upper part of the figure, and the measurement result of the phase difference between the polarizations is shown in the lower part of the figure. The electric field is raised to 5.2 [MV / m] over about 20 seconds, and further up to 6.2 [MV / m] over 7 seconds, and then the power is turned off according to the circuit time constant. Lowering.
[0035]
From FIG. 8, it can be seen that the detected phase difference well follows the square of the applied electric field.
[0036]
Table 1 shows the Kerr constant measurement results under various gases and pressures. Since the Kerr constant has pressure dependence, each numerical value is a value normalized around 0.1 MPa.
[Table 1]

[0037]
Therefore, when light is transmitted through the gas insulator 11 exhibiting dielectric anisotropy, the polarization state changes according to the dielectric anisotropy of the gas insulator 11. That is, the dielectric anisotropy of the gas insulator 11 is determined according to the voltage of the high voltage conductor 12, and the polarization state of the transmitted light is determined according to the dielectric anisotropy of the gas insulator 11. A certain correspondence relationship is established between the voltage applied to the gas and the polarization state of the transmitted light of the gas insulator 11.
[0038]
The detection light 14 is transmitted through the electric field affected region 13 of the gas insulator 11 with a known test voltage applied to the high voltage conductor 12, and the polarization state of the transmitted light is measured. For example, a specific direction component of transmitted light is extracted by an analyzer and the light intensity is measured. Then, the same measurement is repeated by changing the test voltage applied to the high voltage conductor 12. By repeatedly performing the measurement with the test voltage changed in this way, the correspondence between the voltage applied to the high voltage conductor 12 and the polarization state of the transmitted light transmitted through the electric field affected region 13 can be obtained.
[0039]
Even in the same gas insulating device 16, if the optical path 15 is different, the correspondence between the voltage applied to the high voltage conductor 12 and the polarization state of the transmitted light changes. Therefore, the correspondence between the voltage applied to the high voltage conductor 12 and the polarization state of the transmitted light is obtained for the optical path 15 for actually measuring the voltage.
[0040]
After obtaining the correspondence between the voltage applied to the high voltage conductor 12 and the polarization state of the transmitted light in this way, the detection light 14 is transmitted through the optical path 15 (step S3), and the correspondence relationship is determined from the polarization state of the transmitted light. Is used to determine the voltage of the high voltage conductor 12 (step S4). That is, by applying the actually measured polarization state of transmitted light to the correspondence relationship, a voltage corresponding to the polarization state can be derived, and this voltage becomes the voltage of the high-voltage conductor 12.
[0041]
As the detection light 14, light having a wavelength that can pass through the gas insulator 11 is used. Since the tank 17 is a light shielding body that does not transmit the detection light 14, a window that transmits the detection light 14 is formed in a portion on the optical path 15 of the tank 17. In the present embodiment, an incident window 18 through which the detection light 14 is incident and an emission window 19 through which the transmitted light that has passed through the electric field affected region 13 is emitted are formed in a portion on the optical path 15 of the tank 17.
[0042]
The

windows

18 and 19 are configured by opening a hole 17 a in the tank 17 and closing the hole 17 a with a plug 20 of a material that can transmit the detection light 14. The stopper 20 is made of, for example, glass. For example, a conductive coat is applied to the outer surface of the stopper 20 so that the potentials of the

windows

18 and 19 are equal to the potential of the tank 17. The potential of the tank 17 is lowered to the ground potential, and if the conductive coating is not applied to the

windows

18 and 19, there is a possibility that a voltage is generated at the plug 20 portion. Therefore, by applying a conductive coating on the outer surface of the plug 20, the potential of the plug 20 is lowered to the ground potential, preventing the generation of voltage and further improving the safety in insulation. For example, an ITO (indium tin oxide) film is formed as the conductive coat. In this embodiment, a glass piece on which an ITO film is formed is fitted into the hole 17a as a plug 20 and adhered airtightly to form

windows

18 and 19. The sizes of the

windows

18 and 19 are preferably as small as possible as long as the detection light 14 can pass through. By making the

windows

18 and 19 small, insulation safety can be further improved.
[0043]
For example, as shown in FIGS. 2 and 3, a light source 21 for the detection light 14 is attached to the incident window 18. A detector 22 is attached to the exit window 19. The detector 22 includes an analyzer and a light receiver. The output of the light receiver is supplied to a voltage recording device (not shown), for example. The tank 17 is dropped to the ground potential, and the light source 21 and the detector 22 can be attached to the outer peripheral surface of the tank 17.
[0044]
When the detection light 14 is irradiated from the light source 21 toward the incident window 18, the detection light 14 enters the analyzer of the detector 22 from the emission window 19 through the electric field effect region 13 of the gas insulator 11.
[0045]
Since the gas insulator 11 has anisotropy in the dielectric constant in the electric field affected region 13, the detection light 14 incident on the gas insulator 11 is a straight line in the direction where the dielectric constant is large and the direction where the dielectric constant is small (orthogonal to each other). It is divided into polarized waves and propagates through the optical path 15 at each refractive index (speed). As a result, as shown in FIG. 4, there is a phase difference between the linearly polarized waves in the direction with a large dielectric constant and the direction with a small dielectric constant. The wavefront is deformed. Therefore, when attention is paid to the specific direction component of the transmitted light after passing through the electric field effect region 13 of the gas insulator 11 (for example, the component in the direction of 45 degrees with respect to the x axis and the y axis in FIG. 4), The light intensity depends on the magnitude of the dielectric anisotropy of the gas insulator 11. When light of this specific direction component is extracted by an analyzer in an appropriate direction determined from the electric field direction of the detector 22 and is incident on the light receiver, a signal corresponding to the light intensity, that is, the dielectric anisotropy of the electric field affected region 13 is increased. A signal corresponding to the size can be obtained. In the case of a material having a distribution in refractive index anisotropy, this phenomenon appears to be averaged.
[0046]
Then, a test voltage having a known value is applied to the high voltage conductor 12 to measure the light intensity of the component in the specific direction of the transmitted light, and this measurement is performed a plurality of times while changing the test voltage. A relational expression between the voltage value applied to the high voltage conductor 12 and the light intensity of the specific direction component of the transmitted light is fitted based on the measurement results of a plurality of times (step S2). For example, a relational expression such as Expression 2 is fitted.
[Expression 2]
Light intensity = A × cos (B × square of voltage + C)
However, A, B, and C are coefficients determined for each relational expression set for each gas insulation device 16.
After obtaining such a relational expression, the voltage of the high voltage conductor 12 of the gas insulation device 16 in operation is measured. By measuring the light intensity of the component in the specific direction of the transmitted light (step S3), the voltage of the high voltage conductor 12 can be obtained from the above relational expression (step S4).
[0047]
Actually, since an alternating current having a commercial frequency, for example, a frequency of 50 Hz or 60 Hz, flows through the high voltage conductor 12 of the gas insulating device 16, the light intensity of the specific direction component of the transmitted light changes at that frequency. By continuously irradiating the detection light 14 from the light source 21, the light intensity of the component in the specific direction of the transmitted light can be continuously measured, and the voltage of the high voltage conductor 12 can be continuously monitored.
[0048]
Thus, in the present invention, the voltage value of the high voltage conductor 12 can be measured using the gas insulator 11 that insulates the high voltage conductor 12. For this reason, the equipment required for voltage measurement becomes compact, and the equipment cost can be reduced.
[0049]
Moreover, since the voltage of the high voltage conductor 12 can be measured by transmitting the detection light 14 through the electric field effect region 13 of the gas insulator 11 that insulates the high voltage conductor 12, the voltage can be easily measured.
[0050]
In addition, since the optical path 15 to be actually measured is determined, and the voltage measurement is performed by obtaining the above-described correspondence relationship with respect to the optical path 15, the degree of freedom in selecting the optical path 15 is high, and it can be applied to various places. That is, even the same gas insulation device 16 can be applied to various places, and the members other than the high voltage conductor 12 of the gas insulation device 16 can be selected and applied. . For these reasons, it is possible to provide a voltage measurement method that is versatile and easy to use.
[0051]
In the above description, the case of measuring the voltage of the high voltage conductor 12 of the gas insulating device 16 is taken as an example, but it is needless to say that the present invention is not limited to this. For example, the present invention may be applied to measure the voltage of a bushing lead wire or the like.
[0052]
Further, the member 12 to be subjected to voltage measurement is not necessarily a conductor, and may be, for example, a solid insulating material such as a bushing or an insulator or other members. Like bushing 碍 It is also possible to measure the potential sharing on the surface of the tube.
[0053]
FIG. 5 shows an example in which the potential sharing (voltage applied to the portion) of the surface of the bushing (hereinafter referred to as the bushing 12) as the member 12 is measured. For example, when measuring the potential sharing of a portion indicated by reference numeral 23 in FIG. 5, the detection light 14 is allowed to pass through the electric field affected region 13 around the portion 23.
[0054]
Also in this case, the optical path 15 for transmitting the detection light 14 to the electric field affected region 13 of the gas 11 is determined (step S1), and the correspondence between the voltage of the portion 23 and the polarization state of the transmitted light of the optical path 14 is obtained in advance. Then (step S2), the detection light 14 is transmitted through the optical path 15 (step S3), and the voltage of the portion 23 can be obtained from the polarization state of the transmitted light using the correspondence (step S4).
[0055]
The potential sharing of the surface of the bushing 12 is determined according to the shape and dielectric constant of the bushing 12. Therefore, the potential sharing of the portion 23 can be calculated based on the voltage of the lead wire (not shown) of the bushing 12. That is, in this case, in step S2, the detection light 14 is transmitted through the optical path 15 while applying a test voltage of a known value to the lead line, and the potential sharing of the portion 23 calculated based on the test voltage of the lead line is performed. What is necessary is just to obtain | require the correspondence with the polarization state of transmitted light.
[0056]
In the embodiment of FIG. 5, the detection light 14 emitted from the light source 21 and passing through the electric field effect region 13 is reflected by the mirror 24, and once again passes through the electric field effect region 13 and is incident on the detector 22. ing. That is, the optical path 15 is determined so that the detection light 14 passes through the electric field affected region 13 twice. In this way, the detection light 14 passes through the electric field affected region 13 twice, so that the polarization state of the gas transmitted light incident on the detector 22 can be changed more greatly, and the detection sensitivity is improved and more accurately. Voltage measurements can be made.
[0057]
Further, the number of times the detection light 14 passes through the electric field affected region 13 is not limited to two times, and it is needless to say that the detection light 14 may pass through the electric field affected region 13 three times or more. By allowing the detection light 14 to pass through the electric field effect region 13 many times, the distance that the detection light 14 passes through the region having dielectric anisotropy can be increased, and the polarization state of the transmitted light can be changed more greatly. Can do. FIG. 6 shows a concept in which the detection light 14 is reciprocated three times to pass through the region having the dielectric anisotropy, that is, the electric field affected region 13 six times to improve the detection sensitivity six times. It is to be noted that the detection sensitivity can be improved by reflecting the detection light 14 and passing the electric field affected region 13 a plurality of times in the same manner as in the embodiments other than the embodiment shown in FIG.
[0058]
In addition, when calculating | requiring a correspondence in step S2 of FIG. 1, the several correspondence, ie, the correspondence which changed the temperature (gas density) of the electric field influence area | region 13 little by little, is calculated | required, and it measures (step S3). ) A suitable correspondence may be selected according to the actual temperature (gas density) of the electric field effect region 13 and the voltage value may be obtained using the selected correspondence (step S4).
[0059]
Next, an example of an embodiment of a method for estimating surface contamination using gas transmitted light to which the present invention is applied will be described. This surface contamination estimation method estimates surface contamination based on the same principle as the voltage measurement method described above. For example, surface contamination such as bushings and insulators installed outdoors can be estimated. This will be specifically described with reference to FIGS.
[0060]
Now, it is assumed that the bushing 12 of FIG. 5 is installed outdoors. A fouling substance adheres to the surface of the bushing 12. Some fouling substances, such as salt, show conductivity when dissolved in water. When fouling substances adhering to the surface of the bushing 12 are wetted by rain or moisture, the portion becomes conductive, so the potential sharing (voltage applied to that portion) is reduced, and the potential of the other portion is reduced by that amount. Sharing becomes large. For this reason, if the deposit of the fouling substance is left unattended, the insulation cannot be maintained and there is a risk that discharge will occur. In the present invention, since the surface contamination of the bushing 12 can be estimated, the replacement time of the bushing 12 can be known.
[0061]
The estimation method of surface fouling of the present invention is as follows: When a bushing or insulator installed in the gas 11 is an estimation target (hereinafter referred to as a member 12), and an electric field is generated in the gas 11 existing around the estimation target In this method, the optical path 15 through which the detection light 14 is transmitted to the electric field affected region 13 of the gas 11 is determined (step S5), the detection light 14 is transmitted through the optical path 15 and the polarization state of the transmitted light is determined. Is observed (step S6), and the surface contamination of the member 12 is estimated based on the change in the polarization state (step S7).
[0062]
As the surface contamination accumulates, the potential sharing of the portion 23 changes, so the electric field around the portion 23 also changes, and the dielectric anisotropy of the surrounding electric field affected region 13 also changes. Since the polarization state of the transmitted light in the optical path 15 also changes in accordance with the change in the dielectric anisotropy of the electric field affected region 13, the polarization state of the transmitted light in the optical path 15 is eventually monitored. Based on this, it is possible to estimate the surface contamination of the portion 23. Further, since the amount of change in the polarization state of transmitted light increases as the amount of accumulated dirt increases, it is possible to estimate not only the presence or absence of surface contamination but also the accumulated state of surface contamination.
[0063]
The potential sharing may be measured at a plurality of locations on the surface of the bushing 12. Although it is possible to estimate the surface contamination of the bushing 12 even if there is only one measurement location, it is possible to estimate which portion of the contamination material is accumulated by measuring the potential sharing at multiple locations and estimating the surface contamination. It becomes possible to do. In addition, when there is only one measurement location, the change in the measurement value is caused by surface contamination, or the change in the applied voltage of the lead wire (conductor passing through the bushing 12) Sometimes it is difficult to judge whether or not. On the other hand, such determination is facilitated by measuring at a plurality of locations.
[0064]
The present invention is also suitable for measuring the surface contamination of an insulating member such as an insulator attached to a steel tower or the like. In particular, since the insulator is arranged at a high place such as a steel tower, it is difficult to detect the surface contamination, but in the present invention, the light source 21 and the detector 22 can be installed at a position away from the insulator. Yes, surface contamination can be easily estimated for insulators placed at high places. That is, the light source 21 such as a laser beam and the detector 22 are installed on the ground, and the detection light 14 is reflected by the mirror 24 installed in the vicinity of the insulator, thereby measuring the potential sharing applied to the insulator surface on the steel tower from the ground. can do. For this reason, it is possible to easily monitor the accumulation state of the surface contamination of the insulator, which is very effective for maintenance of the equipment.
[0065]
Further, when breakage such as a crack occurs in the member 12 such as a bushing or an insulator, the potential sharing of the portion decreases, and the dielectric anisotropy of the surrounding electric field effect region 13 changes. Therefore, since the polarization state of the transmitted light in the optical path 15 also changes, it is possible to detect breakage such as a crack in the member 12 based on the change in the polarization state of the transmitted light.
[0066]
Each of the above-described embodiments is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention. For example, the detection light 14 is modulated and transmitted through the optical path 15, the transmitted light transmitted through the electric field affected region 13 of the optical path 15 is synchronously detected, and the correspondence is used from the polarization state of the transmitted light after the synchronous detection. The voltage of the member 12 may be obtained, or the surface contamination of the member 12 may be estimated by observing the polarization state of the transmitted light after synchronous detection. The gas 11 may fluctuate due to an electromagnetic force or the like caused by a temperature change or a steep current change such as a short-circuit current. Further, the output of the light source 21 may fluctuate. The fluctuation of the gas 11 and the fluctuation of the light source 21 cause a noise factor with respect to the light intensity of the specific direction component of the transmitted light that is the measurement output, so that the measurement output includes noise. In the present invention, the detection light 14 is phase-modulated at a certain frequency, detected by the photodetector 22, and then subjected to synchronous detection using a filter device such as a lock-in amplifier, that is, only a specific frequency component is extracted. Only the frequency component of the previously applied modulation can be extracted. Thereby, noise factors such as fluctuations in the gas 11 having different frequencies and fluctuations in the light source 21 can be removed, and the S / N (signal / noise) ratio can be improved.
[0067]
【The invention's effect】
As described above, in the voltage measurement method using the gas transmitted light according to claim 1, an optical path for transmitting the detection light to the electric field affected region of the gas is determined, Measurement target The correspondence relationship between the voltage of the light and the polarization state of the transmitted light in the optical path is obtained in advance, the detection light is transmitted through the optical path, and the correspondence relationship is utilized from the polarization state of the transmitted light. Measurement target Since the voltage used for the instrument is originally used as a part of the measuring instrument, the voltage is measured by connecting an instrument transformer. Large equipment is not required for insulation, and the compact structure Measurement target Can be measured. For this reason, equipment cost can be reduced. In addition, it is possible to provide a voltage measurement method that has a high degree of freedom in selecting an optical path, is versatile, and is easy to use. Furthermore, the voltage applied to the surface of an insulating member such as a bushing or insulator can be measured.
[0068]
In the voltage measurement method using the gas transmitted light according to claim 2, Measure high voltage conductors or bushing lead wires of gas insulation equipment. , Measurement target Let the detection light pass through the optical path while applying a known test voltage to Measurement target The correspondence relationship between the voltage applied to and the polarization state of the transmitted light is obtained in advance.
[0069]
Further, in the voltage measurement method using the gas transmitted light according to claim 3, ,window Secure the optical path using do it Voltage measurements can be made.
[0070]
Further, in the voltage measurement method using gas transmitted light according to claim 4, the potential of the window is set. tank For example, when a window is formed in a light shield such as a gas tank of a gas insulation device, the potential of the window can be lowered to the ground potential by dropping the potential of the gas tank to the ground potential. Safer than above.
[0071]
Further, in the voltage measurement method using the gas transmitted light according to claim 5, the optical path is determined so as to reflect the detection light and pass through the electric field affected region a plurality of times, so that the polarization state of the transmitted light changes greatly. Measurement sensitivity can be improved.
[0072]
Furthermore, in the voltage measurement method using gas transmitted light according to claim 6, the detected light is modulated and transmitted through the optical path, the transmitted light transmitted through the optical path is synchronously detected, and the polarization state of the transmitted light after synchronous detection is detected. From the above correspondence Measurement target Therefore, noise factors such as gas fluctuations and light source fluctuations can be removed from the measurement output, and the S / N (signal / noise) ratio of the measurement output can be improved. Measurement accuracy can be improved.
[0073]
Further, in the method for measuring surface contamination using gas transmitted light according to claim 7, an optical path through which the detection light is transmitted to the electric field effect region of the gas is determined, and the detection light is transmitted through the optical path, and the polarization state of the transmitted light is determined. And based on the change in the polarization state Estimation target The surface contamination is estimated so that, for example, an insulator placed at a high altitude or hidden from observation from the ground Estimation target It is possible to estimate the surface contamination of the part. Also with simple equipment Estimation target Can be estimated.
[0074]
Further, in the method for estimating surface contamination using gas transmitted light according to claim 8, since the optical path is determined so as to reflect the detection light and pass through the electric field affected region a plurality of times, the polarization state of the transmitted light is changed. It can be changed greatly, and the sensitivity of observation of the polarization state can be improved.
[0075]
Further, in the method for estimating surface contamination using gas transmitted light according to claim 9, the detection light is modulated and transmitted through the optical path, and the transmitted light transmitted through the optical path is synchronously detected, and the transmitted light after the synchronous detection is detected. Since the polarization state is observed, noise factors such as gas fluctuations and light source fluctuations can be removed from the measurement output, and the S / N (signal / noise) ratio of the measurement output can be improved. The accuracy of observation of the polarization state can be improved.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an example of an embodiment of a voltage measurement method using gas-transmitted light according to the present invention.
FIG. 2 is a perspective view when the present invention is applied to a gas insulating device.
FIG. 3 is a cross-sectional view when the present invention is applied to a gas insulating device.
FIG. 4 is an explanatory diagram conceptually showing how detection light is polarized by a gas having dielectric anisotropy.
FIG. 5 is a conceptual diagram when the present invention is applied to a bushing.
FIG. 6 is a conceptual diagram for determining an optical path so as to reflect detection light and pass through an electric field affected region a plurality of times.
FIG. 7 is a flowchart showing an example of an embodiment of a surface contamination estimation method using gas transmission light according to the present invention.
FIG. 8: Applied electric field and CO ₂ It is a figure which shows the phase difference measurement result of no polarization.
[Explanation of symbols]
11 Gas
12 members
13 Field effect area of gas
14 Detection light
15 light path
17 Tank (shading body)
18 Entrance window
19 Exit window

Claims

The measurement object is either a high-voltage conductor or bushing lead wire of a gas insulation device as a conductor installed in a gas, or a bushing or insulator as a solid insulation material installed in a gas. in the method of the voltage when the electric field in said gas has occurred that exists to determine the optical path for transmitting the detection light in the electric field region of influence of the gas, the transmitted light voltage and the optical path of the measurement object A correspondence relationship with the polarization state of the light is obtained in advance, the detection light is transmitted through the optical path, and the voltage of the measurement target is obtained from the polarization state of the transmitted light using the correspondence relationship. Voltage measurement method using gas transmitted light.

The voltage applied to the measurement object by transmitting the detection light through the optical path while applying a test voltage of a known value to the measurement object, with the high voltage conductor of the gas insulation device or the lead wire of the bushing as the measurement object. The voltage measurement method using gas-transmitted light according to claim 1, wherein a correspondence relationship between the polarization state of the transmitted light and the polarization state of the transmitted light is obtained in advance.

The high-voltage conductor of the gas insulating device is the measurement object , the gas is filled in a tank that accommodates the measurement object , and the light source of the detection light is provided outside the tank. The voltage measurement method using gas transmission light according to claim 1 or 2, wherein the detection light is irradiated toward the gas from a provided window.

4. The voltage measuring method using gas transmitted light according to claim 3, wherein the potential of the window is made equal to the potential of the tank.

5. The voltage measurement method using gas-transmitted light according to claim 1, wherein the optical path is determined so as to reflect the detection light and pass through the electric field affected region a plurality of times.

The detected light is modulated and transmitted through the optical path, the transmitted light transmitted through the optical path is synchronously detected, and the voltage of the measurement target is obtained from the polarization state of the transmitted light after synchronous detection using the correspondence relationship. The voltage measurement method using the gas transmitted light according to any one of claims 1 to 5.

The installed bushing or insulator and estimation target in a gas, in the estimation method of the front surface contamination when the electric field is generated in said gas existing around the estimated target, detected in the electric field region of influence of the gas An optical path for transmitting light is determined, a detection light is transmitted through the optical path, a polarization state of the transmitted light is observed, and surface contamination of the estimation target is estimated based on a change in the polarization state. A method for estimating surface fouling using gas transmitted light.

8. The method for estimating surface contamination using gas transmitted light according to claim 7, wherein the optical path is determined so as to reflect the detection light and pass through the electric field affected region a plurality of times.

9. The detection light according to claim 7, wherein the detection light is modulated and transmitted through the optical path, the transmitted light transmitted through the optical path is synchronously detected, and a polarization state of the transmitted light after synchronous detection is observed. A method for estimating surface fouling using gas transmitted light.