JP3767748B2

JP3767748B2 - Transmission line current detector

Info

Publication number: JP3767748B2
Application number: JP2003132830A
Authority: JP
Inventors: 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: 2006-04-19
Anticipated expiration: 2023-05-12
Also published as: JP2004333418A

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。
〈ｓ〉・〈Ｈ〉＝｜〈ｓ〉｜・｜〈Ｈ〉｜・cosγ
＝Ｈｘ・cosα＋Ｈｙ・（sinα・cosβ）／sinβ＋Ｈｚ・sinα・・・式（１４）
cosγ＝[Ｈｘ・cosα＋Ｈｙ・（sinα・cosβ）／sinβ＋Ｈｚ・sinα]／（｜〈ｓ〉｜・｜〈Ｈ〉｜）・・・式（１５）
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]
BACKGROUND 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 respect to the transmission line.
[0002]
[Prior art]
A power transmission line current detection device that detects a current flowing in each power transmission line of a plurality of phases in a non-contact state includes a magnetic field sensor arranged for each phase power transmission line. FIG. 6 shows an example of magnetic field sensor arrangement in the transmission line current detection device, and 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 caused by the currents of the transmission lines A to C, and currents flowing through the phase transmission lines A, B, and C are 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 power transmission line of the other phase in addition to the magnetic field generated by the power transmission line of the corresponding phase. In order to accurately detect the current flowing in each phase transmission line A, B, C, it is necessary to remove the influence of the magnetic field generated by the other phase transmission line, and various techniques for this purpose have been proposed.
[0004]
For example, in Japanese Patent Laid-Open No. 2002-162423, a current flowing through 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. A technique has been proposed.
[0005]
This method detects the current flowing through the transmission line according to the following principle. First, when there is only one linear infinitely long transmission line, the detection voltage V output by the magnetic field sensor separated from the distance r by this is expressed by the equation (1) according to the well-known Bio-Savart law.
V = k · I / (2πr) (1)
Where k: magnetic field voltage conversion coefficient of the magnetic field sensor, r: distance between the transmission line and the magnetic field sensor, and I: transmission line current.
In order to obtain the transmission line current I from the detection voltage V output from the magnetic field sensor, (2πr / k) may be multiplied by the detection voltage V.
[0006]
Next, in a three-phase power transmission system with three linear infinitely long transmission lines, the magnetic field sensors Sa installed in the relative positional relationship as shown in FIG. The detection voltage Va is expressed by equation (2).
Va = k · Ia / (2πr1) + k · Ib / (2πr2) + k · Ic / (2πr3) (2)
Where, Va: detection voltage of the magnetic field sensor Sa, r1: distance between the magnetic field sensor Sa and the a-phase transmission line A, r2: distance between the magnetic field sensor Sa and the b-phase transmission line B, r3: magnetic field sensors Sa and c The distance between the phase transmission lines C, Ia: current of the a-phase transmission line A, Ib: current of the b-phase transmission line B, and Ic: current of the c-phase transmission line C.
[0007]
When the conversion coefficient of the magnetic field sensor Sa for each of the transmission lines A, B, and C, that is, ki / 2πri (where i = 1 to 3) is set to k11, k12, and k13, Equation (2) becomes 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 expressed by equations (4) and (5).
Vb = k21 · Ia + k22 · Ib + k23 · Ic (4)
Vc = k31 · Ia + k32 · Ib + k33 · Ic (5)
When these equations (3) to (5) are expressed in matrix, equation (6) shown in FIG. 7 is obtained. In order to obtain Ia, Ib, and Ic from Expression (6), the inverse matrix of the matrix kii of the first term on the right side of Expression (6) is multiplied to both sides of the expression, and Expression (7) shown in FIG. You can see that.
[0008]
When the inverse matrix of the matrix kii in the first term on the right side of Equation (7) is set as the matrix Kii, Equation (7) becomes Equation (8) shown in FIG. As can be seen from equation (8), by multiplying a constant voltage-current conversion coefficient matrix Kii determined by the relative arrangement of the magnetic field sensor and the power transmission line with the detection voltage matrix Vi of the magnetic field sensor, each phase of the three-phase three-wire The current of the transmission line can be obtained.
[0009]
In addition, as a method for obtaining the optimum value of the voltage-current conversion coefficient in the distribution line, a plurality of magnetic field sensors corresponding to the plurality of distribution lines and a variable representing the distance between the distribution lines of the plurality of phases by sampling the outputs of the plurality of magnetic field sensors are sampled. Japanese Patent Application Laid-Open No. 8-233868 discloses a method for obtaining an optimum value by changing a variable representing the distance between the two in a predetermined installation allowable range.
[0010]
[Problems to be solved by the invention]
As is apparent from the above, 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 obtained by determining a moving range in which the magnetic field sensor is installed in advance 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 held by a pin insulator 2 as shown in FIG. 10, but the electric wire 1 as shown in FIG. 3 is applied to a transmission line in which the steel tower 4 to which the magnetic field sensor S is attached is inclined with respect to the electric wire 1 because the assumption that the electric wire is linear is not valid. , The exact current is not detected. That is, when a non-contact magnetic field sensor is arranged on a transmission tower in a multi-phase transmission line, a current detection device using a voltage-current conversion coefficient that is a function only of the distance between the multi-phase transmission line and the plurality of magnetic field sensors Then, there exists a problem that the electric current which is flowing into each phase power transmission line cannot be detected correctly.
[0012]
The method for 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. It is necessary to. In the transmission line, as shown in FIG. 12, there are cases where two transmission lines A to C are supported on one tower 4, and in such a case, six parameters (r 11) per one magnetic field sensor. , R12, r21, r22, r31, r32), a total of 36 parameters. Calculation for obtaining 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 difficult in practice.
[0013]
Furthermore, when the dimensions of the electric wire retaining shape are different for each phase transmission line, there is a problem that inputting the electric wire retaining shape dimensions for each phase requires a lot of labor and further complicates the calculation method.
[0014]
The present invention has been considered in view of the above-mentioned problems, and it is possible to use a multi-phase power transmission line in which electric wire retention is curved or a transmission line in which there are two or more multi-phase power transmission lines. 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 problems, the present invention is arranged in a non-contact state in the vicinity of each of a plurality of phase transmission lines, and outputs a plurality of induced voltages due to currents flowing through the respective phase transmission lines. And a calculation means for converting the output voltage of the plurality of magnetic field sensors into a current flowing in each phase transmission line while removing the influence of the magnetic field from the other phase transmission line using a voltage-current conversion coefficient. In the transmission line current detecting device, the voltage-current conversion coefficient is defined between the minute portions of the transmission lines of the plurality of phases and the plurality of magnetic field sensors that are finely divided with respect to an appropriate distance before and after the steel tower on which the magnetic field sensor is installed. It is a function of a distance, a minute portion of the transmission lines of the plurality of phases, and a three-dimensional angle of the plurality of magnetic field sensors.
[0016]
According to this feature, a plurality of phases of transmission lines in the vicinity of a steel tower in which a magnetic field sensor is installed are divided into minute parts, a voltage-current conversion coefficient between the minute part and the magnetic field sensor is calculated, and appropriate before and after the steel tower. Since the voltage-current conversion coefficient of the magnetic field sensor for the transmission line is obtained by integrating the distance, the current flowing in each phase transmission line is determined by the other-phase transmission line regardless of the wire retention shape of the transmission line. The influence of the magnetic field can be removed and accurately detected.
[0017]
Further, the present invention provides a minute portion of the plurality of phase transmission lines and the plurality of the plurality of phase transmission lines so that a current value converted by the voltage-current conversion coefficient becomes a current value of each phase transmission line measured at an electric station. 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]
Furthermore, it is composed of a tower station installed in the tower and 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 station to the tower station. It is characterized by that.
[0019]
Thus, by correcting the voltage-current conversion coefficient so as to be the current value of each phase transmission line measured at the electric station, even if the dimensions of the wire retention shape are different for each phase transmission line, a typical wire retention shape It becomes possible to accurately detect the current flowing in each phase power transmission line only by inputting. Therefore, it is possible to improve the efficiency of the input operation of the voltage-current conversion coefficient calculation data, and it becomes unnecessary to adjust the attachment of the magnetic field sensor, and the efficiency of the attachment operation can be improved.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below 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, and this embodiment is an example applied to a three-phase three-wire transmission line as shown in FIG. .
[0021]
Three-phase currents of a, b, and c phases flow through the three-phase power transmission lines A, B, and C, respectively. The three magnetic field sensors Sa, Sb, Sc for each phase a, b, c are configured by winding a coil with an appropriate number of turns around the center of the rod-shaped core, and are safe from the corresponding transmission lines A, B, C. It is arranged at an appropriate position on the steel tower separated by a distance that can secure In this case, the arrangement positions of the magnetic field sensors Sa, Sb, and Sc are not critical, and may be shifted vertically and horizontally as long as a safe distance is secured.
[0022]
The detection voltages of the magnetic field sensors Sa, Sb, and Sc are separately input to the corresponding filters 11a, 11b, and 11c. The filters 11a to 11c remove noise from the detection voltages of the magnetic field sensors Sa, Sb, and Sc. The filter output from which the noise has been removed (detection 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, from the voltage-current conversion coefficient calculation input unit 14, 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 an angle with the power transmission lines A, B, and C, and a wire retaining shape are input.
[0024]
The conversion coefficient calculation unit 15 uses the data input from the voltage-current conversion coefficient calculation input unit 14 to relate the detected voltages of the magnetic field sensors Sa, Sb, Sc to the currents of the respective phase transmission lines A, B, C. Is calculated. This calculation method will be described later in detail.
[0025]
The voltage-current conversion coefficient matrix calculation unit 16 forms a matrix of the conversion coefficients obtained by the conversion coefficient calculation unit 15, and further obtains a voltage-current conversion coefficient matrix that is an inverse matrix of the coefficient group by calculation.
[0026]
The current detection unit 13 multiplies the digital data of the detected voltage waveforms of the magnetic field sensors Sa, Sb, Sc input via the A / D converter 12 by a voltage-current conversion coefficient matrix to thereby obtain a three-phase transmission line 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 other-phase transmission line is removed.
[0027]
The above components are provided in the tower office. In the present embodiment, the tower station is further provided with a transmission unit 17 and a current comparison unit 18 to enable correction of the voltage-current conversion coefficient matrix based on the transmission line current information transmitted from the parent station.
[0028]
The electric station measurement unit 19 of the master station measures the current flowing through 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 gives the current comparison unit 18 the transmission line current information transmitted from the master station.
[0029]
The current comparison unit 18 compares each phase transmission line current transmitted from the electric power station measurement unit 19 with the current detected by the current detection unit 13 to detect a difference between the two, and the conversion coefficient calculation unit 15 Output. As a result, the conversion coefficient output from the conversion coefficient calculator 15 is corrected, and the voltage-current conversion coefficient matrix output from the voltage-current conversion coefficient matrix calculator 16 is corrected.
[0030]
Next, the operation of this embodiment will be described. First, data input in the voltage / current conversion coefficient calculation input unit 14 will be described. 2 (a) and 2 (b) are diagrams showing an arrangement relationship and a wire retaining shape of one power transmission line 5 (A, B, or C) and a magnetic field sensor S (Sa, Sb, Sc) corresponding thereto, As shown in FIG. 5A, the power transmission line 5 is held by the insulator 3 in a curved shape divided by points M and N.
[0031]
The voltage / current conversion coefficient calculation input unit 14 develops modeling and arrangement of the retaining shape of the transmission line and the installation position of the magnetic field sensor S on the same coordinates from the tower information obtained by referring to the tower structure diagram. Find the coordinates of the position. In modeling the retention shape of the transmission line 5, the modeling may be a circle or an ellipse, or the retention shape of the transmission line 5 may be plotted. In addition, when the dimensions of the retaining shape are different in each phase, a typical retaining shape is modeled.
[0032]
Next, calculation in the conversion coefficient calculation unit 15 will be described. First, as shown in FIG. 2A, the transmission line 5 is divided into three sections at points M and N, each section is divided into, for example, 100 minute portions ΔL, and the magnetic field sensor S based on unit current is divided into minute portions ΔL. Let us consider the magnetic field strength ΔH received from.
[0033]
Assuming that the magnetic field sensor S is at a point P in the space and the unit current I (A) flows through a minute part ΔL that is r (m) away from the point P, the point P due to the unit current I (A) of the minute part ΔL. The magnetic field strength ΔH is expressed by Equation (9) according to Bio-Savart's law.
ΔH = I · ΔL · sinθ / (4πr ² ) (9)
Here, r is the distance between the minute portion ΔL and the magnetic field sensor S, θ is the angle between the tangent line of the minute portion ΔL and the straight line connecting the point P−ΔL, and I is the unit current.
[0034]
Since the direction of ΔH is not clear in equation (9), in order to clarify this, I and r are considered as vectors <I> and <r>, and the vector <ΔH> of ΔH is used by their vector product. It represents with Formula (10). In addition, <> shows that it is a vector, and a vector is described similarly similarly below.
<ΔH> = [ΔL / (4πr ³ )] · <I> × <r> (10)
Here, <I> is a vector in the tangential direction of magnitudes I and ΔL, and <r> is a vector in the direction of point P from the magnitudes r and ΔL.
[0035]
From the equation (10), the x component ΔHx, the y component ΔHy, and the z component ΔHz of <ΔH> are expressed by the equations (11x) to (11z).
ΔHx = [ΔL / (4πr ³ )] · (Iy · rz−Iz · ry) (11x)
ΔHy = [ΔL / (4πr ³ )] · (Iz · rx−Ix · rz) (11y)
ΔHz = [ΔL / (4πr ³ )] · (Ix · ry−Iy · rx) (11z)
Here, Ix, Iy, Iz: x, y, z components of <I>, rx, ry, rz: x, y, z components of <r>.
[0036]
Using the coordinate values modeled in the voltage-current conversion coefficient calculation input unit 14, the x, y, and z components of <ΔH> are calculated, and numerical integration is performed for three sections for each component. The generated magnetic field <H> is calculated. In addition, about the area before and behind a steel tower, what is necessary is just to integrate to the suitable distance range in which the induced voltage by the electric current which flows into the transmission line 5 cannot be disregarded.
[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 is equal to the z component Hz 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, the magnetic field received by the magnetic field sensor S when the angle between the magnetic field sensor S and <H> is γ. | <Hs> | is represented by Expression (12).
| <Hs> | = | <H> | .cosγ Expression (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) (13)
From the equation (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 represented by the equation (15).
<S> ・ <H> = | <s> | ・ | <H> | ・ cosγ
= Hx · cosα + Hy · (sinα · cosβ) / sinβ + Hz · sinα (14)
cosγ = [Hx · cosα + Hy · (sinα · cosβ) / sinβ + Hz · sinα] / (| <s> | · | <H> |) (15)
The detection voltage V of the magnetic field sensor S by the current Ip flowing through the power transmission line 5 is expressed by Expression (16).
V = k · | <Hs> | · Ip = k · | <H> | · cosγ · Ip (16)
Here, k is the magnetic field voltage conversion coefficient of the magnetic field sensor S.
[0038]
As apparent from the above, the detection voltage V of the magnetic field sensor S is a straight line connecting the distance r between the minute portion ΔL of the power transmission line 5 and the magnetic field sensor S, the tangent line of the minute portion ΔL and the center point −ΔL of the magnetic field sensor S. And θ 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 (17)
Where Va is the detection voltage of the magnetic field sensor Sa, r1 to r3 is the distance between the magnetic field sensor Sa and the minute portions of the a-phase, b-phase and c-phase transmission lines A, B and C, and θ1 to θ3 is the magnetic field sensor Sa. And the angle between the tangents of the a-phase, b-phase, and c-phase power transmission lines A, B, and C, α: the angle with the X axis of the magnetic field sensor Sa, β: the 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 a conversion coefficient. Ia to Ic: currents of power 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 set as T11, T12, and T13, respectively, Equation (17) becomes Equation (18).
Va = T11 · Ia + T12 · Ib + T13 · Ic (18)
Similarly, the detection voltages Vb and Vc of the magnetic field sensors Sb and Sc are expressed by Expression (19) and Expression (20), respectively.
Vb = T21 · Ia + T22 · Ib + T23 · Ic (19)
Vc = T31 · Ia + T32 · Ib + T33 · Ic (20)
As described above, the conversion coefficient calculation unit 15 calculates the conversion coefficients T11 to T33 by calculation. The voltage / current conversion coefficient matrix calculation unit 16 forms a matrix of the conversion coefficients T11 to T33 obtained by the conversion coefficient calculation unit 15 and obtains a voltage / current conversion coefficient matrix which is an inverse matrix thereof. The current detector 13 solves the simultaneous equations of Expressions (18) to (20) by matrix calculation to obtain the currents Ia to Ic flowing in the phase transmission lines A to C.
[0041]
Next, correction of the voltage / current conversion coefficient matrix will be described. The correction process of the voltage-current conversion coefficient matrix described below is appropriately executed when the apparatus is attached or when the apparatus is inspected. Transmission line current information obtained by measuring the current flowing through each of the three-phase transmission lines A, B, and C at the electric station measurement 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 provided to the current comparison unit 18.
[0042]
The current comparison unit 18 compares each phase transmission line current transmitted from the electric station measurement unit 19 with the current detected by the current detection unit 13. This comparison method may be a method of comparing current sampling values themselves or a method of comparing current values and numerical values of phase angles. As a result of this comparison, the difference in which phase current is how large is obtained. This difference is given to the conversion coefficient calculator 15.
[0043]
The conversion coefficient calculation unit 15 sequentially detects the position data of the magnetic field sensor (transmission line and magnetic field sensor) from the conversion coefficient corresponding to the current of the phase with the large difference until the difference given by the current comparison unit 18 falls within the set allowable range. And the voltage-current conversion coefficient matrix calculation unit 16 obtains a voltage-current conversion coefficient matrix based on the changed conversion coefficient and supplies the voltage-current conversion coefficient matrix to the current detection unit 13. When the difference given by the current comparator 18 falls within the allowable range, the voltage-current conversion coefficient matrix at that time is held and the correction process is stopped.
[0044]
It should be noted that Va to Vc in Equation (18) to Equation (20) are calculated based on the measured values at the tower station and the transmission line current information from the parent station, and the voltage-current conversion coefficient matrix is corrected so that they are the same. You may make it do. After stopping the correction process, the current flowing through each phase transmission line is calculated using the held voltage-current conversion coefficient matrix.
[0045]
According to this correction method, correction is performed for each phase without using the vector sum, so that the parameters used for the calculation can be reduced. In this example, three parameters are required for each phase, and it is not necessary to change nine parameters for three phases at once. 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 pylon station. For example, the current of a multi-phase transmission line at the same time is measured and recorded by an electric station and a transmission line current detection device of a tower station, and the current value recorded at the electric station is input to the transmission line current detection device later. This may be performed, or the calculation of the conversion coefficient or voltage-current conversion coefficient matrix is performed by a personal computer, and the conversion coefficient or voltage-current conversion coefficient matrix obtained as a result is input to the transmission line current detection device. May be.
[0047]
The present invention is not limited to the curved transmission line 5 divided into three sections as shown in FIG. 2, but can also be applied to other types of retention transmission lines. FIG. 3 shows a transmission line 5 having a retaining shape by a suspended insulator 6 arranged on the steel tower 4. In the case of this retaining shape, if there is no intermediate section divided by point M and point N in FIG. 2 (a) and it is considered that point M and point N match, the voltage-current conversion coefficient matrix is set as described above. Can be calculated.
[0048]
FIG. 4 shows a case where the power transmission line 5 is bent and supported by the insulator 3 arranged on the steel tower 4. Even in such a case, the voltage / current conversion coefficient matrix is calculated by dividing the power transmission line 5 into minute portions. Thus, the current of the transmission line 5 can be accurately detected.
[0049]
Further, in the case of a three-phase three-wire four-line power transmission line 5 as shown in FIG. 5, twelve magnetic field sensors S equal to the number of power transmission lines 5 are arranged corresponding to the transmission lines of each phase, 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 even in such a case.
[0050]
【The invention's effect】
As described above, according to the present invention, an appropriate distance before and after the tower on which the magnetic field sensor is installed, to the output voltage of the plurality of magnetic field sensors arranged in a non-contact state with respect to each of the plurality of phase transmission lines. Is a voltage-current conversion coefficient that is a function of the distance between a minute portion of a plurality of phase transmission lines and a plurality of magnetic field sensors and a three-dimensional angle of the plurality of phase transmission line minute portions and the plurality of magnetic field sensors. By applying, the current of each phase can be accurately detected even with a transmission line having a curved retaining shape.
[0051]
As a result, accurate zero-phase current and short-circuit current can be measured even with two or more multi-line transmission lines, the transmission current increase / decrease status of the transmission line, the magnitude of failure current at the time of an electrical failure, failure type, failure phase, failure line Monitoring becomes possible. Further, by combining with a known failure section detector or this type of device, processing such as determination of a failure section and determination of a failure direction can be performed.
[0052]
Furthermore, by correcting the voltage-current conversion coefficient using the current value of each phase transmission line measured at the electric power station, even if the dimensions of the wire retention shape are different for each phase transmission line, The current flowing through each phase transmission line can be accurately detected only by input. Therefore, it is possible to improve the efficiency of the input operation of the voltage-current conversion coefficient calculation data, and it becomes unnecessary to adjust the attachment of the magnetic field sensor, and the efficiency of the attachment operation can be improved.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram showing 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 a transmission line retaining shape.
FIG. 4 is a plan view of still another example of a power transmission line retaining shape.
FIG. 5 is a side view showing an example of a magnetic field sensor arrangement for a three-phase four-line power transmission line.
FIG. 6 is an operation explanatory diagram of a conventional transmission line current detection device.
FIG. 7 is a diagram showing a matrix display of Expression (6).
FIG. 8 is a diagram showing a matrix display of Expression (7).
FIG. 9 is a diagram showing a matrix display of Expression (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 power transmission line.
FIG. 12 is an operation explanatory diagram of a conventional transmission line current detection apparatus for a three-phase two-line transmission line.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,5 ... (Transmission, distribution) Electric wire, 2, 3, 6 ... Insulator, 4 ... Steel tower, 11a-11c ... Filter, 12 ... A / D converter, 13 ... Current detection part, 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 ... electricity station measurement unit, A, B, C ... power transmission line, S, Sa, Sb, Sc ... Magnetic field sensor

Claims

A plurality of magnetic field sensors that are arranged in a non-contact state in the vicinity of each of the multi-phase power transmission lines and output an induced voltage due to a current flowing through each phase power transmission line, and the voltage-current conversion coefficient In a transmission line current detection device comprising a calculation means for converting the output voltage of a plurality of magnetic field sensors into a current flowing in each phase transmission line while removing the influence of a magnetic field by another phase transmission line,
The voltage-current conversion coefficient includes the distance between the minute portions of the transmission lines of the plurality of phases and the plurality of magnetic field sensors that are finely divided at an appropriate distance before and after the tower on which the magnetic field sensor is installed, and the transmission of the plurality of phases. A transmission line current detection device, wherein the transmission line current detection device is a function of a minute portion of an electric wire and a three-dimensional angle of the plurality of magnetic field sensors.

Distances between the minute portions of the plurality of phase transmission lines 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 power station. The transmission line current detection device according to claim 1, wherein the current flowing through each phase transmission line is obtained using the corrected voltage-current conversion coefficient.

A tower station installed in the tower and 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 station to the tower station. The transmission line current detection device according to claim 2, wherein