JP2004333418A

JP2004333418A - Transmission line current detection device

Info

Publication number: JP2004333418A
Application number: JP2003132830A
Authority: JP
Inventors: Kazunori Sugimachi; 和則杉町
Original assignee: Nishimu Electronics Industries Co Inc
Current assignee: Nishimu Electronics Industries Co Inc
Priority date: 2003-05-12
Filing date: 2003-05-12
Publication date: 2004-11-25
Anticipated expiration: 2023-05-12
Also published as: JP3767748B2

Abstract

PROBLEM TO BE SOLVED: To provide a transmission line current detection device capable of detecting accurately a current flowing in the transmission line of each phase even in the case of both a transmission line of a plurality of phases wherein a wire anchor is bent, and a transmission line having two or more circuits of the transmission line of a plurality of phases. SOLUTION: Data such as the distance between magnetic field sensors Sa-Sc and the transmission lines A-C, the angle formed therefrom, the shape of the wire anchor are inputted from an input part 14 for voltage-current conversion coefficient calculation. A conversion coefficient calculation part 15 calculates the conversion coefficient for showing the relation between detection voltages of the magnetic field sensors Sa-Sc and a current in the transmission line of each phase by using the inputted data. A voltage-current conversion coefficient matrix calculation part 16 forms a matrix from the conversion coefficients, and determines a voltage-current conversion coefficient matrix which is an inverse matrix of the coefficient group by calculation. A current detection part 13 detects the currents in the transmission lines A-C by multiplying detection voltage waveforms of the magnetic field sensors Sa-Sc inputted through an A/D converter 12 by the voltage-current conversion coefficient matrix. COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、送電線に流れている送電線電流や、短絡、地絡などの電気故障時の電流を、送電線に対し非接触状態で検出、監視することのできる送電線電流検出装置に関する。
【０００２】
【従来の技術】
複数相の各送電線に流れている電流を非接触状態で検出する送電線電流検出装置は、各相送電線に対して配置された磁界センサを備える。図６は、送電線電流検出装置における磁界センサ配置の例を示し、３相の送電線Ａ、Ｂ、Ｃに対してそれぞれ磁界センサＳａ、Ｓｂ、Ｓｃを配置する。送電線Ａ〜Ｃの電流により生じる磁界の変化により磁界センサＳａ〜Ｓｃに誘導電圧が生起され、この誘導電圧に基づいて各相送電線Ａ、Ｂ、Ｃに流れている電流を検出する。
【０００３】
磁界センサＳａ〜Ｓｃの出力は、対応する相の送電線により生じる磁界以外に、他相の送電線により生じる磁界の影響を受ける。各相送電線Ａ、Ｂ、Ｃに流れている電流を正確に検出するには、他相送電線により生じた磁界の影響を除去する必要があり、このための技術が種々提案されている。
【０００４】
例えば、特開２００２−１６２４２３号公報には、３相の送電線と磁界センサの間の距離の関数で表される電圧電流変換係数を用いた式により各相送電線に流れている電流を検出する手法が提案されている。
【０００５】
この手法は、送電線に流れている電流を以下の原理で検出する。まず、直線状無限長の送電線が１本だけある場合に、これから距離ｒだけ離れた磁界センサが出力する検出電圧Ｖは公知のビオ・サバールの法則により、式（１）で表わされる。
Ｖ＝ｋ・Ｉ／（２πｒ）・・・式（１）
ただし、ｋ：磁界センサの磁界電圧変換係数、ｒ：送電線と磁界センサの間の距離、Ｉ：送電線電流である。
磁界センサが出力する検出電圧Ｖから送電線電流Ｉを求めるには、（２πｒ／ｋ）を検出電圧Ｖに乗算すればよい。
【０００６】
次に、直線状無限長の３本の送電線がある３相送電系統において、各相送電線Ａ、Ｂ、Ｃに対して図６に示すような相対位置関係に設置された磁界センサＳａの検出電圧Ｖａは、式（２）で表わされる。
Ｖａ＝ｋ・Ｉａ／（２πｒ１）＋ｋ・Ｉｂ／（２πｒ２）＋ｋ・Ｉｃ／（２πｒ３）・・・式（２）
ただし、Ｖａ：磁界センサＳａの検出電圧、ｒ１：磁界センサＳａとａ相送電線Ａの間の距離、ｒ２：磁界センサＳａとｂ相送電線Ｂの間の距離、ｒ３：磁界センサＳａとｃ相送電線Ｃの間の距離、Ｉａ：ａ相送電線Ａの電流、Ｉｂ：ｂ相送電線Ｂの電流、Ｉｃ：ｃ相送電線Ｃの電流である。
【０００７】
それぞれの送電線Ａ、Ｂ、Ｃに対する磁界センサＳａの変換係数すなわちｋｉ／２πｒｉ（ここで、ｉ＝１〜３）をｋ１１、ｋ１２、ｋ１３とおくと、式（２）は式（３）となる。
Ｖａ＝ｋ１１・Ｉａ＋ｋ１２・Ｉｂ＋ｋ１３・Ｉｃ・・・式（３）
他の磁界センサＳｂ、Ｓｃの検出電圧Ｖｂ、Ｖｃについても、Ｖａと同様に考えることができるので、それぞれの検出電圧は式（４）、式（５）のようになる。
Ｖｂ＝ｋ２１・Ｉａ＋ｋ２２・Ｉｂ＋ｋ２３・Ｉｃ・・・式（４）
Ｖｃ＝ｋ３１・Ｉａ＋ｋ３２・Ｉｂ＋ｋ３３・Ｉｃ・・・式（５）
これらの式（３）〜（５）を行列表記すると、図７に示す式（６）が得られる。式（６）からＩａ、Ｉｂ、Ｉｃを求めるためには、式（６）の右辺第１項の行列ｋｉｉの逆行列を同式の両辺に乗算し、図８に示す式（７）のようにすればよいことが分かる。
【０００８】
式（７）の右辺第１項の行列ｋｉｉの逆行列を行列Ｋｉｉとおくと、式（７）は図９に示す式（８）になる。式（８）から分かるように、磁界センサと送電線との相対配置で決まる定数の電圧電流変換係数行列Ｋｉｉを磁界センサの検出電圧の行列Ｖｉに乗算することにより、３相３線の各相送電線の電流を求めることができる。
【０００９】
また、配電線において電圧電流変換係数の最適値を求める方法として、複数の磁界センサの出力をサンプリングし、複数相の配電線間の距離を表す変数および複数の配電線と対応する複数の磁界センサとの間の距離を表す変数を、予め定めた設置許容範囲において変化させて最適値を求める方法が、特開平８−２３３８６８号公報に記載されている。
【００１０】
【発明が解決しようとする課題】
従来の電流検出装置では、前述から明らかなように、電線が直線状であると仮定して電線と磁界センサの間の距離のみの関数である電圧電流変換係数を用いている。また、電圧電流変換係数の最適値は、磁界センサが設置される移動範囲を予め決め、その移動範囲で３相のベクトル和を用いて求めている。
【００１１】
しかしながら、この方法は、図１０に示すように、電線１がピン碍子２で引き留められているような配電線に適用した場合には問題がないが、図１１に示すような、電線１が碍子３により湾曲して引き留められており、かつ磁界センサＳを取り付ける鉄塔４が電線１に対して傾いているような送電線に適用した場合には、電線が直線状であるという仮定は成立しないので、正確な電流が検出されない。すなわち、複数相の送電線において、送電鉄塔に非接触磁界センサを配置した場合、複数相の送電線と複数の磁界センサの間の距離のみの関数である電圧電流変換係数を用いた電流検出装置では、各相送電線に流れている電流を正確に検出することができないという問題がある。
【００１２】
また、ベクトル和で最適な電圧電流変換係数を求める方法は、相対的な算出方法であり、３相の場合には変換係数ｋ１１〜ｋ３３の９個のパラメータを変更してベクトル和を設定値以下にする必要がある。送電線では、図１２に示すように、１つの鉄塔４に２回線の送電線Ａ〜Ｃが支持される場合もあり、このような場合には１個の磁界センサにつき６個のパラメータ（ｒ１１、ｒ１２、ｒ２１、ｒ２２、ｒ３１、ｒ３２）、合計で３６個のパラメータを含むこととなる。このような多数のパラメータを変更してベクトル和が設定値以下になるようにして電圧電流変換係数の最適値を求める計算は複雑であり、現実的には困難である。
【００１３】
さらに、電線引き留め形状の寸法が各相送電線ごとに異なる場合、各相ごとの電線引き留め形状の寸法を入力するために、多大な労力を要するとともに算出方法がさらに複雑になるという問題がある。
【００１４】
本発明は、前記の問題点にかんがみなされたものであり、電線引き留めが湾曲しているような複数相の送電線でも、複数相の送電線が２回線以上あるような送電線でも、各相送電線に流れている電流を正確に検出できる送電線電流検出装置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】
前記した課題を解決するために、本発明は、複数相の送電線の各々に対して、その近傍に非接触状態で配置され、各相送電線に流れている電流による誘導電圧を出力する複数の磁界センサと、電圧電流変換係数を用いて前記複数の磁界センサの出力電圧を他相送電線による磁界の影響を除去しつつ各相送電線に流れている電流に変換する演算手段とを具備する送電線電流検出装置において、前記電圧電流変換係数は、前記磁界センサを設置する鉄塔の前後適当な距離について微小に分割した前記複数相の送電線の微小部分と前記複数の磁界センサの間の距離と、前記複数相の送電線の微小部分と前記複数の磁界センサの３次元角度との関数であることを特徴とする。
【００１６】
この特徴によれば、磁界センサを設置している鉄塔付近の複数相の送電線を微小部分に分け、該微小部分と磁界センサ間についての電圧電流変換係数を計算し、当該鉄塔の前後適当な距離について積分して送電線に対する磁界センサの電圧電流変換係数を求めるので、送電線の電線引き留め形状がどのようなものであっても、各相送電線に流れている電流を他相送電線による磁界の影響を除去して正確に検出することができる。
【００１７】
また、本発明は、前記電圧電流変換係数により変換された電流値が電気所で計測された前記各相送電線の電流値となるように、前記複数相の送電線の微小部分と前記複数の磁界センサの間の距離と３次元角度とを補正し、該補正した電圧電流変換係数を使用して各相送電線に流れている電流を求めることを特徴とする。
【００１８】
さらに、前記鉄塔に設置され、電圧電流変換係数を有する鉄塔局と、前記電気所で計測された前記各相送電線の電流値を前記鉄塔局に伝送する機能を有する親局とから構成されることを特徴とする。
【００１９】
このように電気所で計測された各相送電線の電流値となるように電圧電流変換係数を補正することにより、電線引き留め形状の寸法が各相送電線で異なる場合でも、代表的電線引き留め形状の入力だけで各相送電線に流れている電流を正確に検出することができるようになる。したがって、電圧電流変換係数算出用データの入力作業の効率を向上させることができ、また、磁界センサの取り付け調整も不要になり、その取り付け作業の効率を向上させることもできる。
【００２０】
【発明の実施の形態】
以下、図面を参照して本発明を説明する。図１は、本発明に係る送電線電流検出装置の実施形態を示す回路ブロック図であり、本実施形態は、図６に示されるような、３相３線式送電線に適用した例である。
【００２１】
３相送電線Ａ、Ｂ、Ｃにはそれぞれａ、ｂ、ｃ相の３相電流が流れている。それぞれの相ａ、ｂ、ｃに対する３個の磁界センサＳａ、Ｓｂ、Ｓｃは、棒状コアの中央部に適当巻数のコイルを巻回して構成され、対応する各送電線Ａ、Ｂ、Ｃから安全を確保できる距離だけ離れた鉄塔上の適当位置に配置される。この場合、磁界センサＳａ、Ｓｂ、Ｓｃの配置位置は臨界的では無く、安全距離が確保されれば、上下左右にずれてもよい。
【００２２】
磁界センサＳａ、Ｓｂ、Ｓｃの検出電圧は、それぞれ別個に、対応のフィルタ１１ａ、１１ｂ、１１ｃに入力される。フィルタ１１ａ〜１１ｃは、磁界センサＳａ、Ｓｂ、Ｓｃの検出電圧からノイズを除去する。ノイズが除去されたフィルタ出力（磁界センサの検出電圧波形）は、Ａ／Ｄ変換器１２でデジタル化された後、電流検出部１３に入力される。
【００２３】
鉄塔構造図を参照し、電圧電流変換係数算出用入力部１４から、磁界センサＳａ、Ｓｂ、Ｓｃと３相送電線Ａ、Ｂ、Ｃの間の距離、磁界センサＳａ、Ｓｂ、Ｓｃと３相送電線Ａ、Ｂ、Ｃとの角度、電線引き留め形状などのデータを入力する。
【００２４】
変換係数計算部１５は、電圧電流変換係数算出用入力部１４から入力されたデータを用いて、磁界センサＳａ、Ｓｂ、Ｓｃの検出電圧と各相送電線Ａ、Ｂ、Ｃの電流との関係を表す変換係数を計算する。この計算の方法については、後で詳細に説明する。
【００２５】
電圧電流変換係数行列計算部１６は、変換係数計算部１５で求められた変換係数を行列化し、さらに、その係数群の逆行列である電圧電流変換係数行列を計算により求める。
【００２６】
電流検出部１３は、Ａ／Ｄ変換器１２を介して入力された磁界センサＳａ、Ｓｂ、Ｓｃの検出電圧波形のデジタルデータに電圧電流変換係数行列を乗算することにより、３相送電線Ａ、Ｂ、Ｃの各々に流れている電流を他相送電線による磁界の影響が除去された形で検出する。
【００２７】
以上の構成部分は、鉄塔局に備えられる。本実施形態では、鉄塔局に、さらに伝送部１７および電流比較部１８を備え、親局から伝送される送電線電流情報による電圧電流変換係数行列の補正を可能にしている。
【００２８】
親局の電気所測定部１９で３相送電線Ａ、Ｂ、Ｃの各々に流れている電流を計測して送電線電流情報を得、これを伝送部２０を介して鉄塔局へ伝送する。鉄塔局の伝送部１７は、親局から伝送されてきた送電線電流情報を電流比較部１８に与える。
【００２９】
電流比較部１８は、伝送されてきた電気所測定部１９での各相送電線電流と電流検出部１３で検出された電流とを比較して両者の差を検出し、変換係数計算部１５に出力する。これにより変換係数計算部１５から出力される変換係数が補正され、さらに、電圧電流変換係数行列計算部１６から出力される電圧電流変換係数行列が補正される。
【００３０】
次に、本実施形態の動作を説明する。まず、電圧電流変換係数算出用入力部１４におけるデータ入力について説明する。図２（ａ）、（ｂ）は、１本の送電線５（ＡまたはＢあるいはＣ）とそれに対する磁界センサＳ（Ｓａ、Ｓｂ、Ｓｃ）の配置関係および電線引き留め形状を示す図であり、同図（ａ）のように、送電線５は、点Ｍ、点Ｎで分けられた湾曲した形状で碍子３により引き留められている。
【００３１】
電圧電流変換係数算出用入力部１４では、鉄塔構造図を参照して得られた鉄塔情報から送電線の引き留め形状のモデリングと配置、磁界センサＳの設置位置を同一座標上に展開し、それらの位置の座標を求める。送電線５の引き留め形状のモデリングでは、円や楕円でモデル化してもよいし、送電線５の引き留め形状をプロットしてもよい。また、各相で引き留め形状の寸法が異なる場合には、代表的な引き留め形状をモデル化する。
【００３２】
次に、変換係数計算部１５での計算について説明する。まず、図２（ａ）に示すように、送電線５を点Ｍ、Ｎで３区間に分け、各区間を、例えば１００の微小部分ΔＬに分割し、単位電流による磁界センサＳが微小部分ΔＬから受ける磁界強度ΔＨを考える。
【００３３】
空間のある点Ｐに磁界センサＳがあり、これからｒ（ｍ）離れた微小部分ΔＬに単位電流Ｉ（Ａ）が流れているものとすると、微小部分ΔＬの単位電流Ｉ（Ａ）による点Ｐの磁界強度ΔＨは、ビオ・サバールの法則により、式（９）で表わされる。
ΔＨ＝Ｉ・ΔＬ・ｓｉｎθ／（４πｒ^２）・・・式（９）
ここで、ｒ：微小部分ΔＬと磁界センサＳの間の距離、θ：微小部分ΔＬの接線と点Ｐ−ΔＬを結ぶ直線との角度、Ｉ：単位電流である。
【００３４】
式（９）ではΔＨの方向が明確ではないため、これを明確にするためにＩとｒをベクトル〈Ｉ〉、〈ｒ〉と考え、ΔＨのベクトル〈ΔＨ〉をそれらのベクトル積を用いて式（１０）で表す。なお、〈〉付きは、ベクトルであることを示し、以下においてもベクトルを同様に表記する。
〈ΔＨ〉＝［ΔＬ／（４πｒ^３）］・〈Ｉ〉×〈ｒ〉・・・式（１０）
ここで、〈Ｉ〉：大きさＩ，ΔＬの接線方向のベクトル、〈ｒ〉：大きさｒ，ΔＬから点Ｐ方向のベクトルである。
【００３５】
式（１０）により〈ΔＨ〉のｘ成分ΔＨｘ、ｙ成分ΔＨｙ、ｚ成分ΔＨｚは式（１１ｘ）〜式（１１ｚ）となる。
ΔＨｘ＝［ΔＬ／（４πｒ^３）］・（Ｉｙ・ｒｚ−Ｉｚ・ｒｙ）・・・式（１１ｘ）
ΔＨｙ＝［ΔＬ／（４πｒ^３）］・（Ｉｚ・ｒｘ−Ｉｘ・ｒｚ）・・・式（１１ｙ）
ΔＨｚ＝［ΔＬ／（４πｒ^３）］・（Ｉｘ・ｒｙ−Ｉｙ・ｒｘ）・・・式（１１ｚ）
ここで、Ｉｘ，Ｉｙ，Ｉｚ：〈Ｉ〉のｘ，ｙ，ｚ成分、ｒｘ，ｒｙ，ｒｚ：〈ｒ〉のｘ，ｙ，ｚ成分である。
【００３６】
電圧電流変換係数算出用入力部１４においてモデル化された座標値を用い〈ΔＨ〉のｘ，ｙ，ｚ成分を算出し、各成分について３つの区間について数値積分し、単位電流Ｉにより点Ｐに発生する磁界〈Ｈ〉を算出する。なお、鉄塔の前後の区間については、送電線５に流れる電流による誘導電圧が無視できない適当な距離範囲まで積分すればよい。
【００３７】
点Ｐに置かれた磁界センサＳがＺ軸と平行であれば，磁界センサＳが受ける磁界強度は〈Ｈ〉のｚ成分のＨｚと等しくなる。しかし，磁界センサＳが図２に示すように、Ｘ軸からα、Ｙ軸からβの角度で傾いていた場合、磁界センサＳと〈Ｈ〉との角度をγとすると磁界センサＳが受ける磁界｜〈Ｈｓ〉｜は式（１２）となる。
｜〈Ｈｓ〉｜＝｜〈Ｈ〉｜・ｃｏｓγ ・・・式（１２）
磁界センサＳ方向の方向ベクトル〈ｓ〉は式（１３）のように表されるので
〈ｓ〉＝（ｘ成分，ｙ成分，ｚ成分）
＝（ｃｏｓα，（ｓｉｎα・ｃｏｓβ）／ｓｉｎβ，ｓｉｎα）・・・式（１３）
磁界センサＳ方向の方向ベクトル〈ｓ〉と磁界〈Ｈ〉の内積の式（１４）から、磁界センサＳと磁界〈Ｈ〉の角度γは式（１５）で表される。

送電線５に流れる電流Ｉｐによる磁界センサＳの検出電圧Ｖは、式（１６）で表される。
Ｖ＝ｋ・｜〈Ｈｓ〉｜・Ｉｐ＝ｋ・｜〈Ｈ〉｜・ｃｏｓγ・Ｉｐ・・・式（１６）
ここで、ｋ：磁界センサＳの磁界電圧変換係数である。
【００３８】
上記より明らかなように、磁界センサＳの検出電圧Ｖは、送電線５の微小部分ΔＬと磁界センサＳの間の距離ｒ、微小部分ΔＬの接線と磁界センサＳの中心点−ΔＬを結ぶ直線との角度θ（ｘ，ｙ，ｚ成分で表される）の関数となり、α、βは、磁界センサＳの設置位置で決まる定数となる。
【００３９】
図６に示すように、３相の送電線Ａ、Ｂ、Ｃがある場合、磁界センサＳａの検出電圧は、式（１７）で表される。
Ｖａ＝Ｔ（ｒ１，θ１，α，β）・Ｉａ＋Ｔ（ｒ２，θ２，α，β）・Ｉｂ＋Ｔ（ｒ３，θ３，α，β）・Ｉｃ・・・式（１７）
ただし、Ｖａ：磁界センサＳａの検出電圧、ｒ１〜ｒ３：磁界センサＳａとａ相、ｂ相、ｃ相の送電線Ａ、Ｂ、Ｃの微小部分の間の距離、θ１〜θ３：磁界センサＳａとａ相、ｂ相、ｃ相の送電線Ａ、Ｂ、Ｃの微小部分の接線との角度、α：磁界センサＳａのＸ軸との角、β：磁界センサＳａのＹ軸との角、Ｔ（ｒ，θ，α，β）：電流Ｉの係数で微小部分ΔＬについて積分した値であり、変換係数とする。Ｉａ〜Ｉｃ：ａ相、ｂ相、ｃ相の送電線Ａ、Ｂ、Ｃの電流である。
【００４０】
今、それぞれの電流Ｉａ、Ｉｂ、Ｉｃに対する係数（変換係数）をそれぞれ、Ｔ１１、Ｔ１２、Ｔ１３と置くと、式（１７）は式（１８）となる。
Ｖａ＝Ｔ１１・Ｉａ＋Ｔ１２・Ｉｂ＋Ｔ１３・Ｉｃ・・・式（１８）
同様に、磁界センサＳｂ、Ｓｃの検出電圧Ｖｂ、Ｖｃはそれぞれ、式（１９）、式（２０）で表される。
Ｖｂ＝Ｔ２１・Ｉａ＋Ｔ２２・Ｉｂ＋Ｔ２３・Ｉｃ・・・式（１９）
Ｖｃ＝Ｔ３１・Ｉａ＋Ｔ３２・Ｉｂ＋Ｔ３３・Ｉｃ・・・式（２０）
以上のようにして、変換係数計算部１５は変換係数Ｔ１１〜Ｔ３３を計算により求める。電圧電流変換係数行列計算部１６は、変換係数計算部１５で求められた変換係数Ｔ１１〜Ｔ３３を行列化し、その逆行列である電圧電流変換係数行列を求める。電流検出部１３は、行列演算により式（１８）〜式（２０）の連立方程式を解いて各相送電線Ａ〜Ｃに流れている電流Ｉａ〜Ｉｃを求める。
【００４１】
次に、電圧電流変換係数行列の補正について説明する。以下に説明する電圧電流変換係数行列の補正処理は、装置取付時や装置点検時などに適宜実行される。親局の電気所測定部１９で３相送電線Ａ、Ｂ、Ｃの各々に流れている電流を計測して得た送電線電流情報を伝送部２０を介して鉄塔局へ伝送する。鉄塔局では、この送電線電流情報を伝送部１７で受け、電流比較部１８に与える。
【００４２】
電流比較部１８は、伝送されてきた電気所測定部１９での各相送電線電流と電流検出部１３で検出された電流とを比較する。この比較の方法は、電流のサンプリング値そのものを比較する方法、あるいは電流値、位相角の数値を比較する方法でよい。この比較の結果、どの相の電流がどれだけ大きいかの差が得られる。この差は変換係数計算部１５に与えられる。
【００４３】
変換係数計算部１５は、電流比較部１８より与えられる差が設定された許容範囲内に入るまで、差の大きい相の電流に対応する変換係数から順次磁界センサの位置データ（送電線と磁界センサの間の距離、角度）を変更し、電圧電流変換係数行列計算部１６は、変更された変換係数に基づいて電圧電流変換係数行列を求めて電流検出部１３に与える。電流比較部１８より与えられる差が許容範囲に入ったらその時の電圧電流変換係数行列を保持して、補正処理を停止する。
【００４４】
なお、鉄塔局での測定値、親局からの送電線電流情報それぞれにより式（１８）〜式（２０）のＶａ〜Ｖｃを計算し、それらが同じになるように電圧電流変換係数行列を補正するようにしてもよい。補正処理を停止した以後は、保持した電圧電流変換係数行列を使用して各相送電線に流れている電流を算出する。
【００４５】
この補正方法によれば、ベクトル和を用いずに各相ごとに補正するため、計算に使用するパラメータを少なくすることができる。本例の場合、パラメータは各相３個ずつでよく、３相分の９個のパラメータを一度に変化させる必要がないため計算が簡単になり、２回線以上の送電線でも一度に変化させるパラメータの増加を抑えることができる。
【００４６】
電圧電流変換係数行列の補正は、親局から鉄塔局へ送電線電流情報を伝送せずに行うこともできる。例えば、同一時刻での複数相送電線の電流を電気所と鉄塔局の送電線電流検出装置とで計測して記録し、後に電気所で記録した電流値を送電線電流検出装置に入力してこれを行うようにしてもよいし、パソコンで変換係数や電圧電流変換係数行列の補正計算を行い、その結果得られた変換係数や電圧電流変換係数行列を送電線電流検出装置に入力するようにしてもよい。
【００４７】
本発明は、図２に示すような３区間に分けられる湾曲引き留め形状の送電線５に限らず、他の形状の引き留め形状の送電線にも適用できる。図３は、鉄塔４に配置された懸垂碍子６による引き留め形状の送電線５を示す。この引き留め形状の場合、図２（ａ）の点Ｍ、点Ｎで分けられた中間の区間がなく、点Ｍと点Ｎとが一致したと考えれば、前記と同様に電圧電流変換係数行列を算出することができる。
【００４８】
図４は、送電線５が鉄塔４に配置された碍子３により曲がって支持される場合であり、このような場合でも送電線５を微小部分に分割して電圧電流変換係数行列を算出することにより、送電線５の電流を正確に検出することができる。
【００４９】
さらに、図５に示すような、３相３線式４回線の送電線５の場合、送電線５の本数に等しい１２の磁界センサＳを各相の送電線にそれぞれ対応して配置し、１２×１２行列の電圧電流変換係数を用いることにより各相送電線５の電流を求めることができるが、このような場合でも本発明は適用できる。
【００５０】
【発明の効果】
以上に説明したように、本発明によれば、複数相の送電線の各々に対して非接触状態で配置された複数の磁界センサの出力電圧に、磁界センサを設置する鉄塔の前後適当な距離について微小に分割した複数相の送電線の微小部分と複数の磁界センサの間の距離と、複数相の送電線の微小部分と複数の磁界センサの３次元角度との関数である電圧電流変換係数を適用することにより、引き留め形状が湾曲した送電線でも各相の電流を正確に検出することができるようになる。
【００５１】
これにより、２回線以上の多回線の送電線でも正確な零相電流や短絡電流を計測でき、送電線路の送電電流増減状況や電気故障時の故障電流の大きさや故障種別、故障相、故障回線などの監視が可能になる。また、公知の故障区間検出器やこの種の装置と組み合わせることにより、故障区間の判定や故障方向の判定などの処理も可能になる。
【００５２】
さらに、電気所で計測された各相送電線の電流値を使用して電圧電流変換係数を補正することにより、電線引き留め形状の寸法が各相送電線で異なる場合でも、代表的電線引き留め形状の入力だけで各相送電線に流れる電流を正確に検出することができるようになる。したがって、電圧電流変換係数算出用データの入力作業の効率を向上させることができ、また、磁界センサの取り付け調整も不要になり、その取り付け作業の効率を向上させることもできる。
【図面の簡単な説明】
【図１】本発明に係る送電線電流検出装置の実施形態を示す回路ブロック図である。
【図２】送電線引き留め形状の一例および本発明による送電線電流検出原理の説明図である。
【図３】送電線引き留め形状の他の例の側面図である。
【図４】送電線引き留め形状のさらに他の例の平面図である。
【図５】３相４回線の送電線に対する磁界センサ配置の例を示す側面図である。
【図６】従来の送電線電流検出装置の動作説明図である。
【図７】式（６）の行列表示を示す図である。
【図８】式（７）の行列表示を示す図である。
【図９】式（８）の行列表示を示す図である。
【図１０】配電線の引き留め形状の例を示す側面図である。
【図１１】送電線の引き留め形状の例を示す側面図である。
【図１２】３相２回線送電線に対する従来の送電線電流検出装置の動作説明図である。
【符号の説明】
１，５…（送、配）電線、２，３，６…碍子、４…鉄塔、１１ａ〜１１ｃ…フィルタ、１２…Ａ／Ｄ変換器、１３…電流検出部、１４…電圧電流変換係数算出用入力部、１５…変換係数計算部、１６…電圧電流変換係数行列計算部、１７，２０…伝送部、１８…電流比較部、１９…電気所測定部、Ａ，Ｂ、Ｃ…送電線、Ｓ，Ｓａ，Ｓｂ，Ｓｃ…磁界センサ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transmission line current detection device capable of detecting and monitoring a transmission line current flowing in a transmission line and a current at the time of an electrical failure such as a short circuit or a ground fault in a non-contact state with the transmission line.
[0002]
[Prior art]
A transmission line current detection device that detects a current flowing in each transmission line of a plurality of phases in a non-contact state includes a magnetic field sensor arranged for each phase transmission line. FIG. 6 shows an example of the arrangement of the magnetic field sensors in the transmission line current detection device, and the magnetic field sensors Sa, Sb, and Sc are arranged for the three-phase transmission lines A, B, and C, respectively. An induced voltage is generated in the magnetic field sensors Sa to Sc due to a change in the magnetic field generated by the currents of the transmission lines A to C, and the current flowing through each of the phase transmission lines A, B, and C is detected based on the induced voltage.
[0003]
The outputs of the magnetic field sensors Sa to Sc are affected by the magnetic field generated by the transmission line of the other phase, in addition to the magnetic field generated by the transmission line of the corresponding phase. In order to accurately detect the current flowing in each of the phase transmission lines A, B, and C, it is necessary to remove the effect of the magnetic field generated by the other phase transmission lines, and various techniques have been proposed for this purpose.
[0004]
For example, Japanese Patent Application Laid-Open No. 2002-162423 discloses that a current flowing in each phase transmission line is detected by an expression using a voltage-current conversion coefficient expressed as a function of a distance between a three-phase transmission line and a magnetic field sensor. Have been proposed.
[0005]
This method detects a current flowing in a transmission line based on the following principle. First, when there is only one linear infinite length transmission line, the detection voltage V output by the magnetic field sensor separated by a distance r from the transmission line is expressed by Expression (1) according to the well-known Bio-Savart law.
V = kI / (2πr) Equation (1)
Here, k is the magnetic field voltage conversion coefficient of the magnetic field sensor, r is the distance between the transmission line and the magnetic field sensor, and I is the transmission line current.
In order to obtain the transmission line current I from the detection voltage V output by the magnetic field sensor, the detection voltage V may be multiplied by (2πr / k).
[0006]
Next, in a three-phase power transmission system having three linear infinite length transmission lines, a magnetic field sensor Sa installed in a relative positional relationship to each of the phase transmission lines A, B, and C as shown in FIG. The detection voltage Va is represented by Expression (2).
Va = k · Ia / (2πr1) + k · Ib / (2πr2) + k · Ic / (2πr3) Equation (2)
Here, Va: the detection voltage of the magnetic field sensor Sa, r1: the distance between the magnetic field sensor Sa and the a-phase transmission line A, r2: the distance between the magnetic field sensor Sa and the b-phase transmission line B, r3: the magnetic field sensors Sa and c Distance between phase transmission lines C, Ia: current of a-phase transmission line A, Ib: current of b-phase transmission line B, Ic: current of c-phase transmission line C.
[0007]
If the conversion coefficients of the magnetic field sensor Sa for the transmission lines A, B, and C, that is, ki / 2πri (where i = 1 to 3) are set to k11, k12, and k13, the equation (2) becomes the equation (3). Become.
Va = k11 ・ Ia + k12 ・ Ib + k13 ・ Ic (3)
Since the detection voltages Vb and Vc of the other magnetic field sensors Sb and Sc can be considered in the same manner as Va, the respective detection voltages are as shown in Expressions (4) and (5).
Vb = k21 · Ia + k22 · Ib + k23 · Ic Expression (4)
Vc = k31 · Ia + k32 · Ib + k33 · Ic Expression (5)
When these equations (3) to (5) are expressed in a matrix, equation (6) shown in FIG. 7 is obtained. In order to obtain Ia, Ib, and Ic from Expression (6), both sides of the same expression are multiplied by the inverse matrix of the matrix kii of the first term on the right side of Expression (6), and as shown in Expression (7) in FIG. It turns out that it is better to make it.
[0008]
If the inverse matrix of the matrix kii of the first term on the right side of the equation (7) is set as a matrix Kii, the equation (7) becomes the equation (8) shown in FIG. As can be seen from equation (8), by multiplying the detected voltage matrix Vi of the magnetic field sensor by a constant voltage-current conversion coefficient matrix Kii determined by the relative arrangement of the magnetic field sensor and the transmission line, each phase of the three-phase three-wire is obtained. The current of the transmission line can be determined.
[0009]
In addition, as a method of obtaining the optimum value of the voltage-current conversion coefficient in the distribution line, the output of a plurality of magnetic field sensors is sampled, a variable representing the distance between the multi-phase distribution lines, and the plurality of magnetic field sensors corresponding to the plurality of distribution lines. Japanese Patent Application Laid-Open No. 8-233868 describes a method of obtaining an optimum value by changing a variable representing a distance between the two in a predetermined installation allowable range.
[0010]
[Problems to be solved by the invention]
As is apparent from the above description, the conventional current detection device uses a voltage-current conversion coefficient that is a function of only the distance between the electric wire and the magnetic field sensor, assuming that the electric wire is linear. Further, the optimum value of the voltage-current conversion coefficient is determined in advance by determining a moving range in which the magnetic field sensor is installed, and using a three-phase vector sum in the moving range.
[0011]
However, this method has no problem when applied to a distribution line in which the electric wire 1 is retained by a pin insulator 2 as shown in FIG. 10, but the electric wire 1 is not used as shown in FIG. When the present invention is applied to a transmission line that is bent and retained by 3 and the steel tower 4 to which the magnetic field sensor S is attached is inclined with respect to the electric wire 1, the assumption that the electric wire is linear is not established. , No accurate current is detected. That is, when a non-contact magnetic field sensor is arranged on a power transmission tower in a multi-phase transmission line, a current detection device using a voltage-to-current conversion coefficient that is a function of only the distance between the multi-phase transmission line and the plurality of magnetic field sensors. Thus, there is a problem that the current flowing in each phase transmission line cannot be detected accurately.
[0012]
The method of obtaining the optimum voltage-current conversion coefficient by the vector sum is a relative calculation method. In the case of three phases, the nine parameters of the conversion coefficients k11 to k33 are changed to make the vector sum equal to or less than the set value. Need to be As shown in FIG. 12, two transmission lines A to C may be supported by one tower 4 in a transmission line. In such a case, six parameters (r11) are required for one magnetic field sensor. , R12, r21, r22, r31, r32), and a total of 36 parameters are included. The calculation to obtain the optimum value of the voltage-current conversion coefficient by changing such a large number of parameters so that the vector sum becomes equal to or less than the set value is complicated and practically difficult.
[0013]
Further, when the dimensions of the wire retaining shape are different for each phase transmission line, there is a problem that a large amount of labor is required and the calculation method becomes more complicated in order to input the dimensions of the wire retaining shape for each phase.
[0014]
The present invention has been made in view of the above-described problems, and is applicable to a multi-phase power transmission line in which wire retention is curved, a multi-phase power transmission line having two or more multi-phase power lines, and An object of the present invention is to provide a transmission line current detection device capable of accurately detecting a current flowing in a transmission line.
[0015]
[Means for Solving the Problems]
In order to solve the above-described problem, the present invention provides a plurality of transmission lines each of which is arranged in a non-contact state in the vicinity of each of the transmission lines of a plurality of phases and outputs an induced voltage by a current flowing through each of the transmission lines of the phases. A magnetic field sensor, and computing means for converting the output voltages of the plurality of magnetic field sensors into currents flowing in each phase transmission line while removing the influence of the magnetic field due to the other phase transmission lines using a voltage-current conversion coefficient. In the transmission line current detection device, the voltage-to-current conversion coefficient is set between the minute portion of the multi-phase transmission line and the plurality of magnetic field sensors that are finely divided for an appropriate distance before and after the steel tower on which the magnetic field sensor is installed. It is a function of a distance and a three-dimensional angle of a minute portion of the multi-phase transmission line and the plurality of magnetic field sensors.
[0016]
According to this feature, the multi-phase transmission line near the tower where the magnetic field sensor is installed is divided into minute parts, the voltage-current conversion coefficient between the minute part and the magnetic field sensor is calculated, and an appropriate value is calculated before and after the tower. Since the distance is integrated and the voltage-current conversion coefficient of the magnetic field sensor with respect to the transmission line is determined, the current flowing through each phase transmission line is determined by the other phase transmission line regardless of the shape of the transmission line. Accurate detection can be achieved by removing the influence of the magnetic field.
[0017]
Further, the present invention provides a method of manufacturing a micro-part of the multi-phase transmission line and the plurality of multi-phase transmission lines so that the current value converted by the voltage-current conversion coefficient is a current value of each phase transmission line measured at an electric substation. The distance between the magnetic field sensors and the three-dimensional angle are corrected, and the current flowing through each phase transmission line is obtained using the corrected voltage-current conversion coefficient.
[0018]
Further, the tower is installed in the tower, the tower station having a voltage-current conversion coefficient, and a master station having a function of transmitting the current value of each of the phase transmission lines measured at the electric substation to the tower station. It is characterized by the following.
[0019]
By correcting the voltage-current conversion coefficient so as to be the current value of each phase transmission line measured at the substation in this way, even if the dimensions of the wire retention shape are different for each phase transmission line, the typical wire retention shape , The current flowing through each phase transmission line can be accurately detected. Therefore, the efficiency of the input operation of the data for calculating the voltage-current conversion coefficient can be improved, and the adjustment of the mounting of the magnetic field sensor becomes unnecessary, and the efficiency of the mounting operation can be improved.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a circuit block diagram showing an embodiment of a transmission line current detection device according to the present invention. This embodiment is an example applied to a three-phase three-wire transmission line as shown in FIG. .
[0021]
Three-phase currents of phases a, b, and c flow through the three-phase transmission lines A, B, and C, respectively. The three magnetic field sensors Sa, Sb, Sc for the respective phases a, b, c are configured by winding a suitable number of coils around the center of the rod-shaped core, and are safe from the corresponding transmission lines A, B, C. Is placed at an appropriate position on the tower that is separated by a distance that can secure In this case, the arrangement positions of the magnetic field sensors Sa, Sb, Sc are not critical, and may be shifted up, down, left, and right as long as a safe distance is secured.
[0022]
The detection voltages of the magnetic field sensors Sa, Sb, Sc are individually input to the corresponding filters 11a, 11b, 11c. The filters 11a to 11c remove noise from the detection voltages of the magnetic field sensors Sa, Sb, Sc. The output of the filter from which noise has been removed (detected voltage waveform of the magnetic field sensor) is digitized by the A / D converter 12 and then input to the current detection unit 13.
[0023]
Referring to the steel tower structure diagram, the distance between the magnetic field sensors Sa, Sb, Sc and the three-phase transmission lines A, B, C, the magnetic field sensors Sa, Sb, Sc and the three-phase Data such as angles with the transmission lines A, B, and C, and the shape of the electric wire detent are input.
[0024]
The conversion coefficient calculation unit 15 uses the data input from the voltage-current conversion coefficient calculation input unit 14 to determine the relationship between the detection voltage of the magnetic field sensors Sa, Sb, Sc and the current of each phase transmission line A, B, C. Is calculated. This calculation method will be described later in detail.
[0025]
The voltage-current conversion coefficient matrix calculation unit 16 converts the conversion coefficients obtained by the conversion coefficient calculation unit 15 into a matrix, and further calculates a voltage-current conversion coefficient matrix that is an inverse matrix of the coefficient group.
[0026]
The current detection unit 13 multiplies the digital data of the detected voltage waveforms of the magnetic field sensors Sa, Sb, and Sc input via the A / D converter 12 by a voltage-current conversion coefficient matrix, thereby three-phase transmission lines A, The current flowing in each of B and C is detected in a form in which the influence of the magnetic field due to the multi-phase transmission line is removed.
[0027]
The above components are provided in the tower bureau. In the present embodiment, the tower station further includes a transmission unit 17 and a current comparison unit 18 to enable correction of the voltage-current conversion coefficient matrix based on transmission line current information transmitted from the master station.
[0028]
The electric station measuring unit 19 of the master station measures the current flowing in each of the three-phase transmission lines A, B, and C to obtain transmission line current information, and transmits this to the tower station via the transmission unit 20. The transmission unit 17 of the tower station supplies the transmission line current information transmitted from the master station to the current comparison unit 18.
[0029]
The current comparing unit 18 compares each phase transmission line current transmitted by the electric substation measuring unit 19 with the current detected by the current detecting unit 13 to detect a difference between the two, and the conversion coefficient calculating unit 15 Output. Thereby, the conversion coefficient output from the conversion coefficient calculation unit 15 is corrected, and further, the voltage-current conversion coefficient matrix output from the voltage-current conversion coefficient matrix calculation unit 16 is corrected.
[0030]
Next, the operation of the present embodiment will be described. First, data input in the voltage-current conversion coefficient calculation input unit 14 will be described. FIGS. 2A and 2B are diagrams showing the arrangement relationship of one transmission line 5 (A, B, or C), the magnetic field sensor S (Sa, Sb, Sc) and the electric wire retaining shape, As shown in FIG. 1A, the power transmission line 5 is held by the insulator 3 in a curved shape divided at points M and N.
[0031]
In the voltage-current conversion coefficient calculation input unit 14, modeling and arrangement of the retaining shape of the transmission line and the installation position of the magnetic field sensor S are developed on the same coordinates from the tower information obtained with reference to the tower structure diagram. Find the coordinates of a location. In the modeling of the retaining shape of the transmission line 5, modeling may be performed using a circle or an ellipse, or the retaining shape of the transmission line 5 may be plotted. If the dimensions of the retaining shape are different in each phase, a representative retaining shape is modeled.
[0032]
Next, the calculation in the conversion coefficient calculator 15 will be described. First, as shown in FIG. 2A, the transmission line 5 is divided into three sections at points M and N, and each section is divided into, for example, 100 minute portions ΔL. Consider the magnetic field intensity ΔH received from
[0033]
Assuming that the magnetic field sensor S is located at a certain point P in the space, and the unit current I (A) flows in the minute portion ΔL separated from the point P by a unit current I (A) of the minute portion ΔL Is represented by equation (9) according to Biot-Savart's law.
ΔH = I · ΔL · sin θ / (4πr ² ) Equation (9)
Here, r is the distance between the minute portion ΔL and the magnetic field sensor S, θ is the angle between the tangent to the minute portion ΔL and the line connecting the points P-ΔL, and I is the unit current.
[0034]
Since the direction of ΔH is not clear in equation (9), I and r are considered as vectors and <r> to clarify this, and the vector <ΔH> of ΔH is calculated using their vector product. It is represented by equation (10). Note that <> indicates a vector, and the vector is similarly described below.
<ΔH> = [ΔL / (4πr ³ )] · × <r> Expression (10)
Here, : a vector in the tangential direction of the magnitude I, ΔL, and <r>: a vector in the direction of the point P from the magnitude r, ΔL.
[0035]
According to Expression (10), the x component ΔHx, the y component ΔHy, and the z component ΔHz of <ΔH> are expressed by Expressions (11x) to (11z).
ΔHx = [ΔL / (4πr ³ )] · (Iy · rz−Iz · ry) Equation (11x)
ΔHy = [ΔL / (4πr ³ )] · (Iz · rx−Ix · rz) Equation (11y)
ΔHz = [ΔL / (4πr ³ )] · (Ix · ry−Iy · rx) Equation (11z)
Here, Ix, Iy, Iz: x, y, z components of , and rx, ry, rz: x, y, z components of <r>.
[0036]
The x, y, and z components of <ΔH> are calculated using the coordinate values modeled in the voltage-current conversion coefficient calculation input unit 14, and numerical integration is performed on each component in three sections. The generated magnetic field <H> is calculated. It should be noted that in the section before and after the tower, the induced voltage due to the current flowing through the transmission line 5 may be integrated to an appropriate distance range that cannot be ignored.
[0037]
If the magnetic field sensor S placed at the point P is parallel to the Z axis, the magnetic field intensity received by the magnetic field sensor S becomes equal to the Hz of the z component of <H>. However, when the magnetic field sensor S is inclined at an angle of α from the X axis and β from the Y axis as shown in FIG. 2, if the angle between the magnetic field sensor S and <H> is γ, the magnetic field sensor S receives | <Hs> | is given by equation (12).
| <Hs> | = | <H> | · cosγ (12)
Since the direction vector <s> in the direction of the magnetic field sensor S is expressed as in Expression (13), <s> = (x component, y component, z component)
= (Cosα, (sinα · cosβ) / sinβ, sinα) Expression (13)
From Expression (14) of the inner product of the direction vector <s> in the direction of the magnetic field sensor S and the magnetic field <H>, the angle γ between the magnetic field sensor S and the magnetic field <H> is expressed by Expression (15).

The detection voltage V of the magnetic field sensor S based on the current Ip flowing through the transmission line 5 is represented by Expression (16).
V = k · | <Hs> | · Ip = k · | <H> | · cosγ · Ip Expression (16)
Here, k is a magnetic field voltage conversion coefficient of the magnetic field sensor S.
[0038]
As is clear from the above, the detection voltage V of the magnetic field sensor S is a distance r between the minute portion ΔL of the transmission line 5 and the magnetic field sensor S, a straight line connecting the tangent of the minute portion ΔL and the center point −ΔL of the magnetic field sensor S. (Represented by x, y, and z components), and α and β are constants determined by the installation position of the magnetic field sensor S.
[0039]
As shown in FIG. 6, when there are three-phase transmission lines A, B, and C, the detection voltage of the magnetic field sensor Sa is expressed by Expression (17).
Va = T (r1, θ1, α, β) Ia + T (r2, θ2, α, β) Ib + T (r3, θ3, α, β) Ic Equation (17)
Where Va is the detection voltage of the magnetic field sensor Sa, r1 to r3 are the distances between the magnetic field sensor Sa and minute portions of the transmission lines A, B, and C of the a-phase, b-phase, and c-phase, and θ1 to θ3 are the magnetic field sensors Sa. , Angles between the tangents of the minute portions of the transmission lines A, B, and C of the a-phase, b-phase, and c-phases, α: an angle with the X axis of the magnetic field sensor Sa, β: an angle with the Y axis of the magnetic field sensor Sa, T (r, θ, α, β): a value obtained by integrating the minute portion ΔL with the coefficient of the current I, which is used as a conversion coefficient. Ia to Ic: currents of transmission lines A, B, and C of a phase, b phase, and c phase.
[0040]
Now, if the coefficients (conversion coefficients) for the currents Ia, Ib, and Ic are T11, T12, and T13, respectively, the equation (17) becomes the equation (18).
Va = T11 · Ia + T12 · Ib + T13 · Ic Equation (18)
Similarly, the detection voltages Vb and Vc of the magnetic field sensors Sb and Sc are expressed by Expressions (19) and (20), respectively.
Vb = T21 · Ia + T22 · Ib + T23 · Ic (19)
Vc = T31 · Ia + T32 · Ib + T33 · Ic Expression (20)
As described above, the conversion coefficient calculator 15 calculates the conversion coefficients T11 to T33. The voltage-current conversion coefficient matrix calculation unit 16 converts the conversion coefficients T11 to T33 obtained by the conversion coefficient calculation unit 15 into a matrix, and obtains a voltage-current conversion coefficient matrix that is an inverse matrix thereof. The current detection unit 13 solves the simultaneous equations of Expressions (18) to (20) by matrix operation, and obtains the currents Ia to Ic flowing through the phase transmission lines A to C.
[0041]
Next, correction of the voltage-current conversion coefficient matrix will be described. The voltage-current conversion coefficient matrix correction process described below is appropriately executed when the device is mounted or the device is inspected. Transmission line current information obtained by measuring the current flowing in each of the three-phase transmission lines A, B, and C by the electric station measuring unit 19 of the master station is transmitted to the tower station via the transmission unit 20. In the tower station, the transmission line current information is received by the transmission unit 17 and is provided to the current comparison unit 18.
[0042]
The current comparing unit 18 compares each of the transmitted transmission line currents of the substation measuring unit 19 and the current detected by the current detecting unit 13. This comparison method may be a method of comparing the current sampling value itself or a method of comparing the current value and the numerical value of the phase angle. The result of this comparison is the difference in which phase currents are large and how large. This difference is provided to the conversion coefficient calculation unit 15.
[0043]
The conversion coefficient calculation unit 15 sequentially stores the position data of the magnetic field sensor (the transmission line and the magnetic field sensor) from the conversion coefficient corresponding to the current of the phase having a large difference until the difference given by the current comparison unit 18 falls within the set allowable range. Is changed, and the voltage-current conversion coefficient matrix calculation unit 16 obtains a voltage-current conversion coefficient matrix based on the changed conversion coefficient, and provides the current-detection unit 13 with the voltage-current conversion coefficient matrix. When the difference given by the current comparison unit 18 falls within the allowable range, the voltage-current conversion coefficient matrix at that time is held, and the correction processing is stopped.
[0044]
It should be noted that Va to Vc in equations (18) to (20) are calculated from the measured values at the tower station and the transmission line current information from the master station, and the voltage-current conversion coefficient matrix is corrected so that they are the same. You may make it. After the correction processing is stopped, the current flowing through each phase transmission line is calculated using the held voltage-current conversion coefficient matrix.
[0045]
According to this correction method, since the correction is performed for each phase without using the vector sum, the parameters used for the calculation can be reduced. In the case of this example, the parameters may be three for each phase, and it is not necessary to change nine parameters for three phases at once, so that the calculation is simplified, and the parameters for changing two or more transmission lines at once are also provided. Increase can be suppressed.
[0046]
The correction of the voltage-current conversion coefficient matrix can be performed without transmitting the transmission line current information from the master station to the tower station. For example, the current of the multi-phase transmission line at the same time is measured and recorded by the electric substation and the transmission line current detection device of the tower bureau, and then the current value recorded at the electric substation is input to the transmission line current detection device. This may be performed, or the correction coefficient of the conversion coefficient or the voltage-current conversion coefficient matrix may be calculated by a personal computer, and the resulting conversion coefficient or voltage-current conversion coefficient matrix may be input to the transmission line current detection device. You may.
[0047]
The present invention can be applied not only to the transmission line 5 having a curved retaining shape divided into three sections as shown in FIG. 2 but also to a transmission line having another retaining shape. FIG. 3 shows the transmission line 5 in the shape of a captive stop by the suspension insulators 6 arranged on the steel tower 4. In the case of this retaining shape, there is no intermediate section divided by the points M and N in FIG. 2A, and if it is considered that the points M and N match, the voltage-current conversion coefficient matrix is calculated in the same manner as described above. Can be calculated.
[0048]
FIG. 4 shows a case where the transmission line 5 is bent and supported by the insulator 3 arranged on the steel tower 4. Even in such a case, the transmission line 5 is divided into minute parts to calculate the voltage-current conversion coefficient matrix. Thereby, the current of the transmission line 5 can be accurately detected.
[0049]
Further, in the case of a three-phase, three-wire, four-circuit transmission line 5 as shown in FIG. 5, twelve magnetic field sensors S equal to the number of transmission lines 5 are arranged corresponding to the transmission lines of each phase, respectively. Although the current of each phase transmission line 5 can be obtained by using the voltage-current conversion coefficient of the × 12 matrix, the present invention can be applied to such a case.
[0050]
【The invention's effect】
As described above, according to the present invention, the output voltage of the plurality of magnetic field sensors arranged in a non-contact state with respect to each of the multi-phase power transmission lines has an appropriate distance before and after the steel tower on which the magnetic field sensors are installed. The voltage-current conversion coefficient which is a function of the distance between the minute portion of the multi-phase transmission line and the plurality of magnetic field sensors and the three-dimensional angle of the minute portion of the multi-phase transmission line and the plurality of magnetic field sensors. Is applied, the current of each phase can be accurately detected even with a transmission line having a detented shape.
[0051]
This makes it possible to accurately measure zero-phase current and short-circuit current even in multi-line transmission lines of two or more lines, increase or decrease of transmission current in transmission lines, magnitude and type of failure current in case of electrical failure, failure type, failure phase, and failure line. Monitoring becomes possible. Further, by combining with a known fault section detector or a device of this type, processing such as determination of a fault section and determination of a fault direction becomes possible.
[0052]
Furthermore, by correcting the voltage-current conversion coefficient using the current value of each phase transmission line measured at the substation, even if the dimensions of the wire retention shape are different for each phase transmission line, the typical wire retention shape The current flowing through each phase transmission line can be accurately detected only by the input. Therefore, the efficiency of the input operation of the data for calculating the voltage-current conversion coefficient can be improved, and the adjustment of the mounting of the magnetic field sensor becomes unnecessary, and the efficiency of the mounting operation can be improved.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram illustrating an embodiment of a transmission line current detection device according to the present invention.
FIG. 2 is an explanatory diagram of an example of a transmission line retaining shape and a transmission line current detection principle according to the present invention.
FIG. 3 is a side view of another example of the transmission line retaining shape.
FIG. 4 is a plan view of still another example of a transmission line retaining shape.
FIG. 5 is a side view showing an example of a magnetic field sensor arrangement with respect to a three-phase four-line transmission line.
FIG. 6 is a diagram illustrating the operation of a conventional transmission line current detection device.
FIG. 7 is a diagram showing a matrix display of equation (6).
FIG. 8 is a diagram showing a matrix display of equation (7).
FIG. 9 is a diagram showing a matrix display of equation (8).
FIG. 10 is a side view showing an example of a retaining shape of a distribution line.
FIG. 11 is a side view showing an example of a retaining shape of a transmission line.
FIG. 12 is a diagram illustrating the operation of a conventional transmission line current detection device for a three-phase two-circuit transmission line.
[Explanation of symbols]
1, 5 ... (transmission and distribution) electric wires, 2, 3, 6 ... insulators, 4 ... steel towers, 11a to 11c ... filters, 12 ... A / D converters, 13 ... current detectors, 14 ... voltage-current conversion coefficient calculation Input unit, 15: conversion coefficient calculation unit, 16: voltage / current conversion coefficient matrix calculation unit, 17, 20: transmission unit, 18: current comparison unit, 19: electric station measurement unit, A, B, C: transmission line, S, Sa, Sb, Sc ... magnetic field sensor

Claims

For each of the multi-phase transmission lines, a plurality of magnetic field sensors arranged in the vicinity thereof in a non-contact state and outputting an induced voltage due to the current flowing through each phase transmission line, and using the voltage-current conversion coefficient, A transmission line current detection device comprising: an arithmetic unit that converts output voltages of a plurality of magnetic field sensors into currents flowing through each phase transmission line while removing the influence of a magnetic field caused by the other phase transmission line;
The voltage-to-current conversion coefficient is a distance between the minute portion of the multi-phase transmission line and the plurality of magnetic field sensors, which are finely divided at an appropriate distance before and after the steel tower on which the magnetic field sensor is installed, and the transmission of the plurality of phases. A transmission line current detection device, which is a function of a minute portion of an electric wire and a three-dimensional angle of the plurality of magnetic field sensors.

The distance between the minute part of the multi-phase transmission line and the plurality of magnetic field sensors so that the current value converted by the voltage-current conversion coefficient becomes the current value of each phase transmission line measured at an electric substation. 2. The transmission line current detecting device according to claim 1, wherein the current flowing through each phase transmission line is obtained by using the corrected voltage-current conversion coefficient.

A tower station installed on the tower, having a voltage-current conversion coefficient, and a master station having a function of transmitting the current value of each phase transmission line measured at the electric substation to the tower station. The transmission line current detection device according to claim 2, wherein: