JP3879792B2 - Distribution system ground fault detection device and power distribution equipment using the ground fault detection device - Google Patents

Description

【０００１】
【発明の属する技術分野】
本発明は、受配電設備で高圧配電線の地絡事故を検出するために用いる地絡検出装置、及び該地絡検出装置を用いた受配電設備に関するものである。
【０００２】
【従来の技術】
配電系統においては、電源変電所から引き出された複数の高圧配電線にネットワーク受配電設備や常用予備受配電設備などの様々な受配電設備が接続されている。また最近では、配電系統に、自家発電設備や太陽光発電設備などの分散型電源が接続されるため、該分散型電源を配電系統と連系させることが必要になっている。
【０００３】
配電系統において、いずれかの高圧配電線で地絡事故が発生した場合には、電源変電所の変圧器と事故が生じた高圧配電線との間に設けられた遮断器に遮断動作を行なわせて、地絡事故が生じた高圧配電線を電源変電所の変圧器から切り離すようにしている。
【０００４】
地絡事故が生じた場合には、事故が生じた高圧配電線を直ちに無電圧状態として、その事故の復旧作業を行う必要がある。ところが、配電系統にネットワーク受配電設備が設けられている場合には、複数の高圧配電線の間がネットワーク受配電設備内の回路を通して相互に接続されるため、事故が発生した高圧配電線を電源変電所の変圧器から切り離しても、他の健全な高圧配電線からネットワーク変圧器を通して、事故が発生した高圧配電線に逆電力の潮流が起る。
【０００５】
ネットワーク受配電設備では、事故が生じた配電線につながるネットワーク変圧器（受電用変圧器）の励磁電流と事故が生じた配電線の対地静電容量を通して流れる充電電流との合成電流から逆電力の潮流が生じたことを、各ネットワーク変圧器の低圧側で検出するネットワーク継電器を各ネットワーク変圧器に対して設けて、該ネットワーク継電器により所定の位相、及びしきい値以上の逆電力の潮流が検出されたときに、ネットワーク変圧器の低圧側に設けられたプロテクタ遮断器を開くことにより、直ちにその回線を事故が生じた高圧配電線から切り離して逆電力の潮流を遮断するようにしている。
【０００６】
【発明が解決しようとする課題】
ネットワーク受配電設備や常用予備受配電設備などの各種の受配電設備が設けられている配電系統に分散型電源が連系している場合には、系統の負荷バランス状態や分散型電源の発電状態等の系統条件によって電力の潮流状況が複雑に変わり、地絡事故の発生がない定常状態でも、ネットワーク受配電設備のネットワーク母線側からネットワーク変圧器を通して高圧配電線側に逆電力の潮流が起ることがある。このような定常時の逆電力の潮流に応答してネットワーク受配電設備内の遮断器が遮断動作を行なうことは避ける必要があるため、系統に分散型電源が連系している場合等の、逆電力の潮流が発生し易い系統条件の下では、ネットワーク受配電設備内で逆電力の潮流を検出している継電器のしきい値を高く設定して、該受配電設備内のプロテクタ遮断器の遮断動作に抑制をかける必要がある。
【０００７】
ところが、高圧配電線側で地絡事故が発生して変電所側の遮断器が開いたときに、ネットワーク変圧器の励磁電流と高圧配電線の対地静電容量を通して流れる充電電流との合成電流は極めて小さいため、各ネットワーク受配電設備内の逆電力検出用の継電器のしきい値を高く設定すると、高圧配電線で地絡事故が発生したときに生じる逆電力の潮流を検出できなくなり、事故が生じた高圧配電線につながるネットワーク受配電設備内の回線を高圧配電線から切り離すことができなくなる。その結果、他の健全な高圧配電線から事故が生じた高圧配電線に給電され続けることになり、事故の復旧のための点検、修理作業等を行なうことができなくなる。
【０００８】
上記のような事態を避けるためには、ネットワーク受配電設備内に高圧配電線の地絡事故を検出する地絡検出装置を設けて、該地絡検出装置が地絡を検出した時に直ちにネットワーク変圧器に直列に接続されているプロテクタ遮断器を開いて、事故が生じた高圧配電線につながるネットワーク受配電設備内の回線を該高圧配電線から切り離すことができるようにしておく必要がある。
【０００９】
配電系統で従来から用いられている地絡検出装置は、零相変流器を用いて地絡事故発生時に流れる零相分を検出するようにしたものが多く、該地絡検出装置によりネットワーク受配電設備内で高圧配電線の地絡事故を検出するためには、ネットワーク変圧器の高圧側の回路に地絡検出装置を接続する必要がある。
【００１０】
ところが、ネットワーク変圧器の高圧側の回路には高い電圧が印加されているため、この回路に零相変流器などの検出器を取り付けることは好ましくない。またネットワーク受配電設備では、ネットワーク変圧器と高圧配電線との間の構成をできるだけ簡素にしたいとの要請があるため、ネットワーク変圧器の高圧側の回路に余計な装置を接続することは避ける必要がある。
【００１１】
そこで、高圧配電線側で生じた地絡事故を、ネットワーク変圧器の低圧側の回路で検出できるようにするのが望ましいが、高圧配電線側で地絡事故が生じた際に流れる零相電流は絶縁変圧器からなるネットワーク変圧器を通らないため、従来の地絡検出装置をネットワーク変圧器の低圧側の回路に接続しても高圧配電線側の地絡事故を検出することはできない。
【００１２】
高圧配電線に高圧側が接続された受電用変圧器を備えたネットワーク受配電設備以外の受配電設備、例えば、低圧側に分散型電源を連系している受配電設備でも、同様の理由により、従来の地絡検出装置を用いて受電用変圧器の低圧側の回路で高圧配電線側の回路の地絡事故を検出することはできない。
【００１３】
本発明の目的は、配電系統に設けられている受電用変圧器の低圧側の回路で高圧配電線側の地絡事故を検出することができるようにした配電系統の地絡検出装置を提供することにある。
【００１４】
本発明の他の目的は、高圧配電線の地絡事故が生じたときにその事故を受電用変圧器の低圧側の回路で検出することにより受電用変圧器の高圧側の回路と低圧側の回路とを切り離して、事故が生じた高圧配電線への給電を停止するようにした受配電設備を提供することにある。
【００１５】
【課題を解決するための手段】
本発明は、電源変電所から引き出された複数の高圧配電線にそれぞれ絶縁変圧器からなる受電用変圧器を備えた受配電設備が接続されている配電系統の高圧配電線で地絡事故が生じたことを検出する地絡検出装置に係わるもので、受電用変圧器の低圧側の回路を流れる３相交流電流を検出する３相交流検出部と、３相交流検出部により検出された３相交流電流の基本波の逆相分を検出する基本波逆相分検出部と、該基本波逆相分検出部により検出された逆相分から地絡事故の発生の有無を判定する地絡判定部とを備えたことを特徴とする。
【００１６】
電源変電所から複数の高圧配電線が引き出されている配電系統において、いずれかの高圧配電線で地絡事故が生じると、変電所の遮断器が動作して事故が生じた高圧配電線を変電所の変圧器から切り離す。このとき、例えば他の健全な高圧配電線側から事故が生じた高圧配電線につながる受電用変圧器の低圧側に給電されるようになっていると、該受電用変圧器の低圧コイルに励磁電流が流れるとともに、該受電用変圧器を通して地絡事故が生じた高圧配電線側に、該高圧配電線の対地静電容量を充電する充電電流が流れる。地絡が生じた高圧配電線に流れる充電電流は不平衡３相交流電流となり、該不平衡３相電流に含まれる成分のうち、正相分と逆相分は受電用変圧器を低圧側から高圧側に通過するため、事故が生じた高圧配電線につながる受電用変圧器の低圧側の回路で逆相分電流の顕著な変化が生じる。
【００１７】
従って、上記のように、受配電設備に設けられた絶縁変圧器の低圧側の回路を流れる３相交流電流から基本波の逆相分を検出するようにすると、検出された逆相分電流を予め定めた判定基準と比較することにより、受配電設備の各変圧器がつながる高圧配電線で地絡事故が生じたか否かを検出することができる。
【００１８】
上記逆相分から地絡事故の有無を判定するには、例えば、一定の時間毎に逆相分を検出するようにしておいて、各検出時刻において検出された逆相分と前回検出された逆相分との差をとることにより逆相分の変化量を検出し、検出された逆相分の変化量が所定の判定基準値以上になったときに地絡事故が発生したと判定するようにすればよい。
【００１９】
また随時検出される逆相分に対して所定の判定基準を定めておいて、随時検出される逆相分が判定基準以上になったときに地絡事故が発生したと判定するようにしてもよい。
【００２０】
上記のように、本発明によれば、配電系統に設けられている各受電用変圧器の低圧側の回路でその回路がつながる高圧配電線で地絡事故が発生したことを検出することができるため、受電用変圧器と高圧配電線との間の回路の構成を簡素にするという要請に応えつつ、各受配電設備で高圧配電線の地絡事故を検出して、事故が生じた高圧配電線につながる回線を該高圧配電線から切り離すなどの措置を講じることができる。
【００２１】
上記基本波逆相分検出部は、例えば、３相交流検出部により検出された３相交流電流を３軸静止座標系におけるベクトル量として扱って該３軸静止座標系の３相交流電流を２軸が互いに直交する２軸静止座標系における２相交流電流に変換する３相／２相変換部と、２軸静止座標系を２相交流電流の基本波正相分の相回転方向または基本波逆相分の相回転方向に回転する第１の２軸回転座標系に変換することにより２相交流電流の基本波正相分及び基本波逆相分の一方を直流電流に変換し、他方を基本波周波数の２倍の周波数の交流電流に変換する第１の回転座標変換部と、第１の回転座標変換部の出力から２相交流電流の基本波正相分を除去して基本波逆相分を抽出するフィルタ手段と、第１の２軸回転座標系を該第１の２軸回転座標系と逆方向に回転する第２の２軸回転座標系に変換することにより、フィルタ手段により抽出された２相交流電流の基本波逆相分を２軸静止座標系における２相交流電流の基本波逆相分に逆変換する第２の回転座標変換部とを備えることにより構成できる。この場合、第２の回転座標変換部から得られる２相交流電流の基本波逆相分を基本波逆相分検出部の検出出力として用いるようにしてもよく、該２相交流電流の基本波逆相分を２相／３相変換することにより得た３相交流電流の基本波逆相分を基本波逆相分検出部の検出出力として用いるようにしてもよい。
【００２２】
上記３相／２相変換部と、第１の回転座標変換部と、フィルタ手段と、第２の回転座標変換部と、地絡判定部とは、コンピュータと、該コンピュータに実行させる所定のプログラムとにより実現することができる。
【００２３】
本発明において、３相不平衡電流の逆相分を検出するための演算は、３相の各相の電流にベクトル演算子ａ［＝exp{ｊ（２π／３)}］及びａ² を乗じることにより逆相分を求める対称座標法によってもよい。
【００２４】
但し、対称座標法により３相不平衡電流の逆相分を求めるためには、ベクトル演算子ａ，ａ² を乗じるための移相演算と、各相電流の平均化処理とを必要とするため、演算に要する時間が長くなり、逆相分を検出するまでに時間がかかるのを避けられない。
【００２５】
これに対し、上記のように、座標変換法により逆相分を求めるようにすれば、演算を比較的短い時間で終えることができるため、逆相分の検出を高速で行なうことができ、逆相分電流の時々刻々の変化を容易かつ迅速に検出することができる。
【００２６】
本発明において、第２の回転座標変換部から得られる２相交流電流の基本波逆相分を基本波逆相分検出部の検出出力として用いるようにした場合には、３相不平衡電流の様相を検証することはできない。しかし、高圧配電線側の回路で地絡事故が生じたことの検出のみを行なうのであれば、第２の回転座標変換部から得られる２相交流電流の基本波逆相分を基本波逆相分検出部の検出出力として用いてもなんら問題はない。
【００２７】
第２の回転座標変換部から得られる２相交流電流の基本波逆相分を２相／３相変換することにより得た基本波３相交流の逆相分を基本波逆相分検出部の検出出力として用いるようにした場合には、高圧配電線側の回路で地絡事故が生じた場合に、その地絡事故を検出することができるだけでなく、受電用変圧器を流れる３相不平衡電流の様相の検証をも行なうことができる。
【００２８】
上記３相交流検出部は、例えば受電用変圧器の低圧側回路に取り付けた変流器により構成できるが、通常、ネットワーク受配電設備などの受配電設備では、受電用変圧器の低圧側の回路に変流器が設けられているので、その既設の変流器を利用して上記３相交流検出部を構成することができる。
【００２９】
本発明に係わる受配電設備は、電源変電所から引き出された高圧配電線に高圧側が接続された絶縁変圧器からなる受電用変圧器と該受電用変圧器の高圧側の回路または低圧側の回路を開閉する遮断器とを備えたもので、受電用変圧器の低圧側の回路に設けられて該受電用変圧器を通して流れる３相交流電流を検出する変流器と、変流器により検出された３相交流電流の基本波の逆相分を検出する基本波逆相分検出部と、基本波逆相分検出部により検出された逆相分から受電用変圧器につながる高圧配電線側の回路で地絡事故が発生したか否かを判定する地絡判定部と、該地絡判定部により地絡事故が発生したと判定した時に遮断器に遮断指令を与える遮断器制御部とを備えたことを特徴とする。
【００３０】
上記受配電設備としては、電源変電所から引き出された複数の高圧配電線にそれぞれ高圧側が接続された絶縁変圧器からなる複数のネットワーク変圧器と、該複数のネットワーク変圧器に対して共通に設けられたネットワーク母線と、各ネットワーク変圧器の低圧側とネットワーク母線との間に設けられたネットワークプロテクタとを備えたネットワーク受配電設備が多く用いられている。ネットワークプロテクタは、対応するネットワーク変圧器の低圧側とネットワーク母線との間に設けられたプロテクタ遮断器と、対応するネットワーク変圧器の低圧側の回路を流れる電流を検出する変流器と、対応するネットワーク変圧器の低圧側から高圧側に逆電力の潮流が生じたことを検出したときにプロテクタ遮断器に遮断指令を与えるネットワーク継電器とを備えていて、ネットワーク継電器が逆電力の潮流を検出したときにプロテクタ遮断器を遮断する。
【００３１】
このようなネットワーク受配電設備に本発明を適用する場合には、上記変流器が検出した３相交流電流の基本波の逆相分を検出する基本波逆相分検出部と、該基本波逆相分検出部が検出した逆相分から対応するネットワーク変圧器につながる回路で地絡事故が発生したか否かを判定する地絡判定部と、地絡判定部が地絡事故が発生したと判定したときにプロテクタ遮断器に遮断指令を与える遮断器制御部とをネットワークプロテクタに設ける。
【００３２】
上記のようにネットワーク受配電設備に地絡検出装置を設けておくと、受配電設備内で高圧配電線側の回路の地絡事故を検出することができるため、地絡事故が検出された高圧配電線につながる受電用変圧器の高圧側の回路と低圧側の回路とを切り離して、事故が生じた高圧配電線への給電を停止するなどの措置を迅速に講じることができるようになる。
【００３３】
【発明の実施の形態】
以下図面を参照して本発明に係わる地絡検出装置の構成例を説明する。
【００３４】
図４は本発明を適用する配電系統の構成例を示したもので、同図において１は発電所２に送電線を通して高圧側が接続された変圧器１A1〜１A3と、変圧器１A1〜１A3のそれぞれの低圧側に接続された母線１B1〜１B3とを備えた電源側変電所である。
【００３５】
変電所１の母線１B1〜１B3にはそれぞれ遮断器１C1〜１C3を介して高圧配電線３ａ〜３ｃが接続されている。母線１B3には更に遮断器１C4を通して高圧配電線３ｄが接続されている。この例では、変圧器１A1〜１A3から母線１B1〜１B3と遮断器１C1〜１C4とを通して配電線３ａ〜３ｄに２０ＫＶ級の特別高圧の電圧が印加されている。
【００３６】
図示してないが、電源変電所１には配電線３ａ〜３ｄを流れる電流が制限値を超えた時に遮断器１C1〜１c4をトリップする過電流継電器（ＯＣ）と、高圧配電線３ａ〜３ｃで地絡事故が発生した時に遮断器１c1〜１C3をトリップする地絡継電器（ＧＲ）とが設けられている。
【００３７】
図示の例では、本発明に係わるネットワーク受配電設備４が高圧配電線３ａ〜３ｃに接続されている。この受配電設備は、高圧配電線３ａ〜３ｃにそれぞれ断路器４Aa〜４Acを通して高圧側が接続されたネットワーク変圧器４Ba〜４Bcと、変圧器４Ba〜４Bcの低圧側にそれぞれプロテクタヒューズ４Ca〜４Ccを通して一端が接続されたプロテクタ遮断器４Da〜４Dcと、遮断器４Da〜４Dcの他端に接続されたネットワーク母線ＢＵＳ1 と、遮断器４Da〜４Dcを制御する遮断器制御部４Ea〜４Ecとを備えている。変圧器４Ba〜４Bcの低圧側の回路には変流器４Fa〜４Fcが取り付けられていて、これらの変流器により検出された３相交流の信号が遮断器制御部４Ea〜４Ecに与えられている。遮断器制御部４Ea〜４Ecにはまたネットワーク変圧器４Ba〜４Bcの低圧側の電圧が与えられている。
【００３８】
遮断器制御部４Ea〜４Ecはそれぞれ、ネットワーク継電器を備えていて、ネットワーク変圧器４Ba〜４Bcの低圧側から高圧側に（ネットワーク母線側ＢＵＳ1 から高圧配電線３ａ〜３ｃ側に）しきい値以上の逆電力の潮流が生じた時に、プロテクタ遮断器４Da〜４Dcをトリップするようになっている。
【００３９】
ネットワーク母線ＢＵＳ1 には、高圧配電線３ａ〜３ｃの特別高圧の電圧（２２ＫＶ）をネットワーク変圧器４Ba〜４Bcにより降圧して得た電圧（例えば４００Ｖ）が印加されている。
【００４０】
図示の例では、プロテクタヒューズ４Ca、プロテクタ遮断器４Da、変流器４Fa及び遮断器制御部４Eaにより、ネットワークプロテクタ４Gaが構成され、プロテクタヒューズ４Cb、プロテクタ遮断器４Db、変流器４Fb及び遮断器制御部４Ebにより、ネットワークプロテクタ４Gbが構成されている。またプロテクタ遮断器４Dc、変流器４Fc及び遮断器制御部４Ecにより、ネットワークプロテクタ４Gcが構成されている。
【００４１】
また、図示の例では、本発明に係わるネットワーク受配電設備以外に、本発明に係わる地絡検出装置を用いた受配電設備として、低圧側に分散型電源を連系した常用予備受配電設備５が高圧配電線３ａ及び３ｂに接続されている。この受配電設備は、配電線３ａ及び３ｂにそれぞれ遮断器５Aa及び５Abを介して高圧側が接続された受電用変圧器５Ｂと、受電用変圧器５Ｂの低圧側に遮断器５Ｃを通して接続された母線ＢＵＳ2 と、変圧器５Ｂの低圧側の回路に取り付けられた変流器５Ｄと、変流器５Ｄの出力及び変圧器５Ｂの低圧側の電圧を入力として、変圧器５Ｂの低圧側から高圧側に逆電力の潮流が生じたことが検出されたときに遮断器５Ｃをトリップする継電器を有する遮断器制御部５Ｅとを備えている。母線ＢＵＳ2 には、特別高圧の電圧を変圧器５Ｂにより降圧して得た電圧（例えば６０００Ｖ）が印加されている。
【００４２】
図示の例では、ネットワーク母線ＢＵＳ1 に開閉器ＳＷ0 を通して配電線用変圧器Ｔr の高圧側が接続されるとともに、開閉器ＳＷ1 〜ＳＷ4 を通して負荷Ａ1 〜Ａ4 が接続されている。また常用予備受配電設備５の母線ＢＵＳ2 には負荷Ａ5 及びＡ6 が接続され、高圧配電線３ｄには、２２［ＫＶ］の負荷Ａ7 が接続されている。
【００４３】
更に、ネットワーク母線ＢＵＳ1 及び常用予備受配電設備の母線ＢＵＳ2 にそれぞれ分散型電源Ｇ1 及びＧ2 が接続されている。
【００４４】
図４には図示してないが、配電系統には更に配電塔などの各種の受配電設備や分散型電源が接続されることがある。
【００４５】
図４に示したような配電系統において、例えば高圧配電線３ａのＸ点で地絡事故が発生した場合には、変電所１に設けられている地絡保護継電器が変圧器１A1と事故が生じた高圧配電線３ａとの間に設けられた遮断器１c1に遮断動作を行なわせて、地絡事故が生じた配電線３ａを変電所の変圧器１A1から切り離す。このとき、健全な高圧配電線３ｂ及び３ｃ側から、ネットワーク受配電設備４内の回路（断路器４Ab−ネットワーク変圧器４Bb−遮断器４Dbの回路及び断路器４Ac−ネットワーク変圧器４Bc−遮断器４Dcの回路）とネットワーク母線ＢＵＳ1 とを通して事故が起きた高圧配電線３ａにつながるネットワーク変圧器４Baに電流が流れ込み、該変圧器４Baの低圧側から高圧側に逆電力の潮流が生じる。このとき、遮断器制御部４Ｅa に設けられたネットワーク継電器は、変圧器４Baの励磁電流と、ネットワーク母線ＢＵＳ1 側から変圧器４Baを通して高圧配電線３ａの対地静電容量Ｃに流れる充電電流との合成電流及び変圧器４Ｂa の低圧側の電圧を検出して逆電力の潮流を検出し、プロテクタ遮断器４Daを開く。
【００４６】
図４に示したネットワーク受配電設備４において、逆電力に対するネットワーク継電器のしきい値を低くしておくと、高圧配電線３ａ〜３ｃに地絡事故が生じていない状態で、分散型電源Ｇ1 からネットワーク母線ＢＵＳ1 とネットワーク変圧器４Ba〜４Bcとを通して配電線３ａ〜３ｃ側に逆電力の潮流が生じたときにもプロテクタ遮断器４Da〜４Dcが遮断動作を行ってしまう。
【００４７】
上記のように定常時の逆電力の潮流に応答してネットワーク受配電設備４内の遮断器が遮断動作を行なうことは避ける必要がある。従って、図４に示したように系統に分散型電源が連系している場合には、受配電設備４内で逆電力の潮流を検出している継電器のしきい値を高く設定して、該受配電設備内の遮断器の動作に抑制をかける必要があり、高圧配電線３ａ〜３ｃ側で地絡事故が生じた時に、事故が生じた高圧配電線につながる回線を切り離すことができなくなることがある。このような事態が生じないようにするためには、ネットワーク受配電設備４内に高圧配電線の地絡事故を検出する地絡検出装置を設けて、該地絡検出装置により高圧配電線の地絡事故が検出された時にネットワーク変圧器の高圧側の回路と低圧側の回路とを切り離すようにしておけばよい。
【００４８】
図１は、本発明に係わる地絡検出装置の全体的な構成を示したもので、同図において、１０ｕ〜１０ｗは配電系統に接続されている絶縁変圧器（図４の例では、ネットワーク変圧器４Ba〜４Bc）の低圧側のＵ，Ｖ，Ｗ３相の回路であり、これらの回路には、変流器ＣＴau，ＣＴav及びＣＴawが取り付けられている。ネットワーク受配電設備のように、絶縁変圧器の低圧側の回路に既に変流器（例えば図４の変流器４Fa〜４Fc）が設けられている場合には、その既設の変流器を変流器ＣＴau〜ＣＴawとして利用することができる。図１に示した例では、変流器ＣＴau，ＣＴav及びＣＴawにより、絶縁変圧器の低圧側の回路を流れる３相交流電流を検出する３相交流検出部１１が構成され、この３相交流検出部１１から得られる３相交流電流の検出値が基本波逆相分検出部１２に与えられている。
【００４９】
基本波逆相分検出部１２は、座標変換法により不平衡３相交流電流の逆相分を検出する部分で、この基本波逆相分検出部は、３相交流検出部１１により検出された３相交流を３軸静止座標系におけるベクトル量として扱って該３軸静止座標系における３相交流電流を２軸が互いに直交する２軸静止座標系における２相交流電流に変換する３相／２相変換部１３と、２軸静止座標系を２相交流電流の基本波正相分の相回転方向または基本波逆相分の相回転方向に回転する第１の２軸回転座標系に変換することにより３相／２相変換部１３が求めた２相交流電流の基本波正相分及び基本波逆相分の一方を直流電流に変換し、他方を基本波周波数の２倍の周波数の交流電流に変換する第１の回転座標変換部１４と、該第１の回転座標変換部１４の出力から２相交流電流の基本波正相分を除去して基本波逆相分を抽出するフィルタ手段１５と、第１の２軸回転座標系を該第１の２軸回転座標系と逆方向に回転する第２の２軸回転座標系に変換することにより、フィルタ手段１５により抽出された２相交流電流の基本波逆相分を２軸静止座標系における２軸静止座標系における２相交流電流の基本波逆相分に逆変換する第２の回転座標変換部１６と、該基本波２相交流を２相／３相変換することにより３相交流電流の基本波逆相分を得る２相／３相変換部１７とからなっている。２相／３相変換部１７から得られる３相交流電流の基本波逆相分は、地絡事故の発生の有無を判定する地絡判定部１８に与えられている。基本波逆相分検出部１２及び地絡判定部１８は、マイクロコンピュータと該マイクロコンピュータに実行させる所定のプログラムとにより実現される。
【００５０】
３相／２相変換部１３は、３相交流検出部１１により検出された３軸静止座標系の３相交流電流を２軸が互いに直交する２軸静止座標系における２相交流電流に変換する部分で、図２に示したように、Ｕ，Ｖ，Ｗの３軸が平面上で互いに１２０度の角度間隔をもって交差する３軸静止座標系をα及びβの２軸が直交する２軸静止座標系に変換する演算（３相／２相変換）を行なって、３軸静止座標系の３相交流Ｉｕ，Ｉｖ及びＩｗ（文章中ではベクトル量を示すドットの表示を省略する。）の信号を、２軸静止座標系の２相交流電流Ｉα及びＩβの信号に変換する。図２に示したように、３軸静止座標と２軸静止座標とがなす角をδとした場合、３相／２相変換の演算は下記の式［数１］の通りである。
【００５１】
【数１】

ここでδ＝０となるように、α軸及びβ軸を定めると、上記の式は次の式［数２］のようになる。
【００５２】
【数２】

また［数２］の式の電流（Ｉｕ，Ｉｖ，Ｉｗ）は、対称座標法により、対称分である零相分電流Ｉ0 、正相分電流Ｉ1 及び逆相分電流Ｉ2 とベクトル演算子ａ及びａ² とを用いて、下記の［数３］のように表される。
【００５３】
【数３】

ここで、零相分電流を無視すると、Ｉ0 ＝０となるため、［数３］の式は下記の［数４］のようになる。
【００５４】
【数４】

［数４］の式を［数２］の式に代入すると、Ｉα及びＩβを求める式は下記の［数５］のようになる。
【００５５】
【数５】

ここで［数５］の行列式を展開してＩαを演算する式を求めると、下記の［数６］のようになる。
【００５６】
【数６】

ベクトル演算子ａ及びａ² はそれぞれ下記の［数７］及び［数８］の通りである。
【００５７】
【数７】

【数８】

［数７］及び［数８］の式を［数６］の式に代入すると、電流Ｉαは下記の式［数９］で与えられる。
【００５８】
【数９】

図３に示すように、基準電圧Ｖ1 と正相分電流Ｉ1 とがなす角度をΦとし、基準電圧Ｖ1 と逆相分電流Ｉ2 がなす角度をθとすると、Ｉ1 （ベクトル）＝Ｉ1 ε^{ｊ（ωｔ＋Φ）}、Ｉ2 （ベクトル）＝Ｉ2 ε^{ｊ（ωｔ＋θ）}と表示できるため、電流Ｉαは、下記の［数１０］で与えられる。
【００５９】
【数１０】

同様にして、電流Ｉβは、下記の式［数１１］から求められる。
【００６０】
【数１１】

上記の式［数１０］及び［数１１］の演算をコンピュータに行なわせることにより、３相／２相変換を行い、２軸静止座標系における２相交流Ｉα及びＩβを求める。
【００６１】
次に第１の回転座標変換部１４は、α，βの２軸静止座標系を２相交流電流の基本波正相分の相回転方向または基本波逆相分の相回転方向に相回転の速度と同速度で回転する第１の２軸回転座標系に変換することにより３相／２相変換部１３が求めた２相交流電流Ｉα及びＩβの基本波正相分及び基本波逆相分の一方を直流成分に変換し、他方を基本波周波数の２倍の周波数成分に変換する。ここで、第１の２軸回転座標系を基本波正相分の相回転方向と同方向に該基本波正相分と同速度で回転させると、基本波正相分は直流分として現れ、基本波逆相分は基本波の周波数の２倍の周波数の成分として現れる。また第１の２軸回転座標系を基本波逆相分の相回転方向と同方向に該逆相分と同速度で回転させると、基本波正相分は基本波周波数の２倍の周波数の成分として現れ、基本波逆相分は直流分として現れる。
【００６２】
第１の２軸回転座標系の回転方向はいずれの方向としてもよいが、以下の説明では、第１の２軸回転座標系の回転方向が、基本波逆相分の相回転方向と同方向（配電系統の電圧ベクトルの回転方向と逆方向）であるとする。
【００６３】
すなわち、２相変換した２相電流Ｉα及びＩβ（いずれもベクトル量）のα，β直交２軸静止座標系を、配電系統の電圧ベクトルと逆方向に、該電圧ベクトルと同速度で回転する直交２軸回転座標系の２相電流Ｉｐ及びＩｑ（ベクトル量）に変換する。直交２軸静止座標系から直交２軸回転座標系への変換式は下記の式［数１２］の通りである。
【００６４】
【数１２】

この行列式を開いて回転座標系の電流Ｉｐを求めると下記の［数１３］のようになる。
【００６５】
【数１３】

同様にして、回転座標系の電流Ｉｑは、下記の［数１４］から求められる。
【００６６】
【数１４】

回転座標系の電流Ｉｐ及びＩｑの第１項は正相分電流Ｉ1 であり、角速度２ωｔの交流成分となる。また第２項は逆相分電流Ｉ2 であり、この逆相分電流Ｉ2 は時間的要素がないので直流成分となる。
【００６７】
図１のフィルタ手段１５は、ローパスフィルタからなっていて、上記Ｉｐ及びＩｑから交流成分（正相分電流）を除去することにより、ｐ，ｑ２軸回転座標系における逆相分電流を抽出する。
【００６８】
ｐ，ｑ２軸回転座標系における逆相分電流のｐ軸成分Ｉp-DCは下記の式［数１５］のようになる。
【００６９】
【数１５】

またｐ，ｑ２軸回転座標系における逆相分電流のｑ軸成分Ｉq-DCは下記の式［数１６］のようになる。
【００７０】
【数１６】

第２の回転座標変換部１６は、第１の回転座標変換部１４により行った演算処理と逆の手順でｐ，ｑ２軸回転座標系（第１の２軸回転座標系）を該第１の２軸回転座標系と逆方向に、該第１の２軸回転座標系と同速度で回転する第２の２軸回転座標系に変換することによって、フィルタ手段１５により抽出された２相逆相分電流（上記［数１５］及び［数１６］の逆相成分Ｉp-DC及びＩq-DCを有する２相交流）を、α，β２軸静止座標系における２相交流電流の基本波逆相分に逆変換する。
【００７１】
２相／３相変換部１７は、第２の回転座標変換部１６から得られる２相交流電流の基本波逆相分を、３相／２相変換部１３で行った処理と逆の手順で３軸静止座標系における３相交流電流の基本波逆相分（受電用変圧器の低圧側の回路から検出された３相交流電流Ｉｕ，Ｉｖ，Ｉｗに含まれる逆相分電流）に変換する。
地絡判定部１８は、基本波逆相分検出部１２により検出された逆相分から地絡事故の発生の有無を判定する。基本波逆相分検出部１２により検出された逆相分から地絡事故の有無を判定するには、例えば、一定の時間毎に逆相分を検出するようにしておいて、各検出時刻において検出された逆相分と前回検出された逆相分との差をとることにより逆相分の変化量を検出し、検出された逆相分の変化量が所定の判定値以上になったときに地絡事故が発生したと判定するようにすればよい。
【００７２】
また随時検出される逆相分に対して所定の判定基準を定めておいて、検出された逆相分が判定基準以上になったときに地絡事故が発生したと判定するようにしてもよい。
【００７３】
上記の例では、第１の回転座標変換部１４で、２軸回転座標系を系統電圧に含まれる逆相分の相回転方向と同方向に回転させたが、該２軸回転座標系を系統電圧に含まれる正相分の相回転方向と同方向に回転させるようにしてもよい。この場合には、逆相分電流が基本波周波数の２倍の周波数の信号として得られるので、フィルタ手段１５はハイパスフィルタにより構成する。
【００７４】
上記の例では、基本波逆相分検出部１２において、第２の回転座標変換部１６により得た２相交流電流の逆相分を２相／３相変換部により３相交流電流の逆相分に変換するようにしたが、このように構成すると、外部回路で地絡事故が生じた場合に、その地絡事故を検出することができるだけでなく、受電用変圧器を流れる３相不平衡電流の様相の検証をも行なうことができる。
【００７５】
なお外部回路で地絡事故が生じたことの検出のみを行なうのであれば、第２の回転座標変換部１６から得られる２相交流電流の基本波逆相分を基本波逆相分検出部の検出出力として用いてもなんら問題はないので、２相／３相変換部１７は省略することもできる。
【００７６】
図１に示した例では、３相交流検出部１１と、基本波逆相分検出部１２と、地絡判定部１８とにより、本発明に係わる地絡検出装置が構成されている。
【００７７】
図４に示した配電系統に本発明を適用する場合には、図１に示した基本波逆相分検出部１２と地絡判定部１８とをネットワークプロテクタ４Ga〜４Gcのそれぞれに設けるとともに、ネットワークプロテクタ４Ga〜４Gcにそれぞれに設けられた地絡判定部１８により高圧配電線３ａ〜３ｃで地絡事故が発生したと判定されたときに、遮断器制御部４Ea〜４Ecがそれぞれ遮断器４Da〜４Dcに遮断指令を与えるようにしておく。
【００７８】
同様に、常用予備受配電設備５にも基本波逆相分検出部１２と地絡判定部１８とを設けるとともに、地絡判定部１８により高圧配電線側で地絡事故が発生したと判定されたときに、遮断器制御部５Ｅが遮断器５Ｃに遮断指令を与えるように構成しておく。また遮断器５Ｃに代えて、遮断器５Aaまたは５Abに遮断指令を与えるようにしてもよい。
【００７９】
上記のように構成すると、例えば図４のＸ点で地絡事故が生じて、高圧配電線３ａが変電所１の母線１B1から切り離されたときに、ネットワーク受配電設備では、遮断器制御部４Eaに設けられた地絡判定部が高圧配電線３ａで地絡事故が発生したことを検出するため、プロテクタ遮断器４Daが開いて、変圧器４Baの高圧側回路と低圧側回路とを切り離す。これにより、他の健全な配電線３ｂ及び３ｃ側から変圧器４Bb及び４Bcとネットワーク母線ＢＵＳ1 と変圧器４Baとを通して高圧配電線３ａ側に逆電力の潮流が生じるのを防止することができる。
【００８０】
また常用予備受配電設備でも、上記のように構成すると、例えば図４のＸ点で地絡事故が生じて、高圧配電線３ａが変電所１の母線１B1から切り離されたときに、遮断器制御部５Ｅに設けられた地絡判定部が高圧配電線３ａで地絡事故が発生したことを検出するため、遮断器５Ｃが開いて、変圧器５Ｂの高圧側回路と低圧側回路とを切り離す。これにより、分散型電源Ｇ2 から母線ＢＵＳ2 と変圧器５Ｂとを通して高圧配電線３ａ側に逆電力の潮流が生じるのを防止することができる。
【００８１】
本発明に係わる地絡検出装置は、低圧側に例えば分散型電源を連系している受配電設備または他の配電系統と連系している受配電設備に適用できる。
【００８２】
【発明の効果】
以上のように、本発明によれば、配電系統に設けられている各受電用変圧器の低圧側の回路でその回路がつながる高圧配電線で地絡事故が発生したことを検出することができるため、受電用変圧器と高圧配電線との間の回路の構成を簡素にするという要請に応えつつ、各受配電設備で高圧配電線の地絡事故を検出して、事故が生じた高圧配電線につながる回線を該高圧配電線から切り離すなどの措置を講じることができる利点がある。
【００８３】
また本発明のように受配電設備を構成すれば、該受配電設備内で高圧配電線側の回路の地絡事故を検出することができるため、地絡事故が検出された高圧配電線につながる受電用変圧器の高圧側の回路と低圧側の回路とを切り離して、事故が生じた高圧配電線への給電を停止するなどの措置を迅速に講じることができる。
【図面の簡単な説明】
【図１】本発明に係わる地絡検出装置の構成例を示したブロック図である。
【図２】本発明に係わる地絡検出装置を説明するために用いるベクトル図である。
【図３】本発明に係わる地絡検出装置を説明するために用いるベクトル図である。
【図４】本発明を適用する配電系統の構成例を示した回路図である。
【符号の説明】
１ 電源変電所
３ａ〜３ｄ 配電線
４ ネットワーク受配電設備
４Aa〜４Ac 断路器
４Ba〜４Bc ネットワーク変圧器
４Da〜４Dc プロテクタ遮断器
４Ea〜４Ec 遮断器制御部
ＢＵＳ1 ネットワーク母線
１１ ３相交流検出部
１２ 基本波逆相分検出部
１８ 地絡判定部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ground fault detection device used for detecting a ground fault in a high voltage distribution line in a power distribution facility, and a power distribution facility using the ground fault detection device.
[0002]
[Prior art]
In a power distribution system, various power distribution facilities such as a network power distribution facility and a regular standby power distribution facility are connected to a plurality of high-voltage distribution lines drawn from a power substation. Recently, since a distributed power source such as a private power generation facility or a solar power generation facility is connected to the power distribution system, it is necessary to connect the distributed power source to the power distribution system.
[0003]
In the distribution system, if a ground fault occurs in any of the high-voltage distribution lines, the circuit breaker provided between the transformer in the power supply substation and the high-voltage distribution line in which the accident has occurred must be cut off. Therefore, the high-voltage distribution line where the ground fault occurred is disconnected from the transformer of the power substation.
[0004]
When a ground fault occurs, it is necessary to immediately restore the high-voltage distribution line where the accident has occurred to a no-voltage state and to recover from the accident. However, when network distribution / distribution equipment is provided in the distribution system, the multiple high-voltage distribution lines are connected to each other through the circuits in the network distribution / distribution equipment. Even if it is disconnected from the transformer at the substation, the reverse power flow will occur in the high voltage distribution line where the accident occurred through the network transformer from other healthy high voltage distribution lines.
[0005]
In the network power distribution facility, the reverse power is calculated from the combined current of the exciting current of the network transformer (power receiving transformer) connected to the distribution line where the accident occurred and the charging current flowing through the ground capacitance of the distribution line where the accident occurred. A network relay that detects the occurrence of power flow on the low voltage side of each network transformer is provided for each network transformer, and a reverse power flow exceeding a predetermined phase and threshold is detected by the network relay. When this happens, the protector breaker provided on the low-voltage side of the network transformer is opened to immediately disconnect the line from the high-voltage distribution line where the accident occurred and to block the reverse power flow.
[0006]
[Problems to be solved by the invention]
When a distributed power source is connected to a power distribution system with various power receiving / distribution facilities such as network power distribution facilities and regular standby power distribution facilities, the load balance status of the system and the power generation status of the distributed power source Even in a steady state where there is no ground fault, the power flow situation of the network changes from the network bus side of the network power distribution facility to the high voltage distribution line side through the network transformer Sometimes. Since it is necessary to avoid that the circuit breaker in the network power distribution facility responds to such a reverse power flow during steady state, such as when a distributed power source is connected to the system, etc. Under system conditions where reverse power flow is likely to occur, the threshold of the relay that detects reverse power flow in the network power distribution facility is set high, and the protector breaker in the power distribution facility It is necessary to control the shut-off operation.
[0007]
However, when a ground fault occurs on the high-voltage distribution line and the circuit breaker on the substation opens, the combined current of the excitation current of the network transformer and the charging current flowing through the ground capacitance of the high-voltage distribution line is If the threshold value of the relay for detecting reverse power in each network power distribution facility is set high, the reverse power flow that occurs when a ground fault occurs in the high-voltage distribution line cannot be detected. The line in the network power distribution facility connected to the generated high voltage distribution line cannot be disconnected from the high voltage distribution line. As a result, power is continuously supplied from another healthy high-voltage distribution line to the high-voltage distribution line in which the accident has occurred, and it becomes impossible to perform inspection, repair work, etc. for recovery from the accident.
[0008]
In order to avoid the above situation, a ground fault detection device for detecting a ground fault in a high-voltage distribution line is provided in the network power distribution facility, and network transformation is immediately performed when the ground fault detection device detects a ground fault. It is necessary to open the protector circuit breaker connected in series with the power supply so that the line in the network power receiving / distributing facility connected to the high voltage distribution line where the accident has occurred can be disconnected from the high voltage distribution line.
[0009]
Many ground fault detection devices conventionally used in distribution systems are designed to detect the zero-phase component that flows when a ground fault occurs using a zero-phase current transformer. In order to detect a ground fault in a high-voltage distribution line in a distribution facility, it is necessary to connect a ground fault detection device to the circuit on the high voltage side of the network transformer.
[0010]
However, since a high voltage is applied to the circuit on the high voltage side of the network transformer, it is not preferable to attach a detector such as a zero-phase current transformer to this circuit. In network power distribution facilities, there is a need to simplify the configuration between the network transformer and the high-voltage distribution line as much as possible, so it is necessary to avoid connecting extra equipment to the high-voltage circuit of the network transformer. There is.
[0011]
Therefore, it is desirable that the ground fault accident that occurred on the high voltage distribution line side should be detected by the circuit on the low voltage side of the network transformer, but the zero-phase current that flows when a ground fault occurs on the high voltage distribution line side. Does not pass through a network transformer composed of an insulation transformer, and therefore, even if a conventional ground fault detector is connected to a circuit on the low voltage side of the network transformer, a ground fault on the high voltage distribution line side cannot be detected.
[0012]
For the same reason, in power receiving / distributing equipment other than network power receiving / distributing equipment provided with a power receiving transformer connected to the high voltage distribution line, for example, power receiving / distributing equipment linked to a distributed power source on the low voltage side, It is not possible to detect a ground fault in the circuit on the high voltage distribution line side with the circuit on the low voltage side of the power receiving transformer using the conventional ground fault detection device.
[0013]
An object of the present invention is to provide a ground fault detection device for a distribution system that can detect a ground fault on the high voltage distribution line side with a low voltage side circuit of a power receiving transformer provided in the distribution system. There is.
[0014]
Another object of the present invention is to detect a ground fault in a high voltage distribution line with a low voltage side circuit of the power receiving transformer by detecting the accident in the low voltage side circuit of the power receiving transformer. An object of the present invention is to provide a power receiving / distributing facility in which power supply to a high-voltage distribution line in which an accident has occurred is stopped by separating the circuit.
[0015]
[Means for Solving the Problems]
According to the present invention, a ground fault occurs in a high-voltage distribution line of a distribution system in which a plurality of high-voltage distribution lines drawn from a power substation are connected to a power distribution facility including a power receiving transformer composed of an insulating transformer. A three-phase AC detection unit for detecting a three-phase AC current flowing in a circuit on the low-voltage side of the power receiving transformer, and a three-phase detected by the three-phase AC detection unit. A fundamental wave antiphase component detecting unit for detecting the antiphase component of the fundamental wave of the alternating current, and a ground fault determining unit for determining the occurrence of a ground fault from the antiphase component detected by the fundamental wave antiphase component detecting unit. It is characterized by comprising.
[0016]
In a distribution system in which multiple high-voltage distribution lines are drawn from a power substation, if a ground fault occurs in any of the high-voltage distribution lines, the circuit breaker in the substation will operate and the high-voltage distribution line will be transformed. Disconnect from the transformer. At this time, for example, when power is supplied to the low voltage side of the power receiving transformer connected to the high voltage power distribution line where the accident occurred from another healthy high voltage distribution line side, the low voltage coil of the power receiving transformer is excited. As current flows, a charging current for charging the ground capacitance of the high-voltage distribution line flows to the high-voltage distribution line side where the ground fault has occurred through the power receiving transformer. The charging current flowing through the high-voltage distribution line in which a ground fault has occurred becomes an unbalanced three-phase AC current. Among the components included in the unbalanced three-phase current, the normal phase component and the reverse phase component are connected to the receiving transformer from the low voltage side. Since it passes to the high voltage side, a significant change in the reverse phase current occurs in the circuit on the low voltage side of the power receiving transformer connected to the high voltage distribution line where the accident occurred.
[0017]
Therefore, as described above, when the negative phase component of the fundamental wave is detected from the three-phase alternating current flowing through the low-voltage side circuit of the insulation transformer provided in the power distribution facility, the detected negative phase current is By comparing with a predetermined criterion, it is possible to detect whether or not a ground fault has occurred in the high-voltage distribution line to which each transformer of the power distribution facility is connected.
[0018]
In order to determine the presence or absence of a ground fault from the reverse phase component, for example, the reverse phase component is detected at regular intervals, and the reverse phase component detected at the detection time and the previously detected reverse phase component are detected. The amount of change in the reverse phase is detected by taking the difference from the phase, and it is determined that a ground fault has occurred when the detected amount of change in the reverse phase is equal to or greater than a predetermined criterion value. You can do it.
[0019]
In addition, a predetermined determination criterion may be set for the negative phase component detected at any time, and it may be determined that a ground fault has occurred when the negative phase component detected at any time exceeds the determination criterion. Good.
[0020]
As described above, according to the present invention, it is possible to detect that a ground fault has occurred in a high-voltage distribution line connected to a low-voltage side circuit of each power receiving transformer provided in the distribution system. Therefore, while responding to the request to simplify the circuit configuration between the power receiving transformer and the high voltage distribution line, each power distribution facility detects a ground fault in the high voltage distribution line and It is possible to take measures such as disconnecting the line connected to the electric wire from the high-voltage distribution line.
[0021]
The fundamental wave anti-phase component detection unit treats, for example, the three-phase alternating current detected by the three-phase alternating current detection unit as a vector quantity in the three-axis stationary coordinate system, and converts the three-phase alternating current in the three-axis stationary coordinate system to 2 A three-phase / two-phase converter for converting into a two-phase alternating current in a biaxial stationary coordinate system whose axes are orthogonal to each other, and a phase rotation direction or a fundamental wave of the two-phase stationary coordinate system for the fundamental positive phase of the two-phase alternating current By converting to the first two-axis rotating coordinate system that rotates in the phase rotation direction of the reverse phase, one of the fundamental wave positive phase component and the fundamental wave reverse phase component of the two-phase AC current is converted to DC current, and the other A first rotation coordinate conversion unit that converts to an alternating current having a frequency that is twice the fundamental wave frequency, and the fundamental wave reverse phase by removing the normal phase of the two-phase alternating current from the output of the first rotation coordinate conversion unit. Filter means for extracting phase components, and the first two-axis rotational coordinate system and the first two-axis rotational coordinate system By converting the second biaxial rotating coordinate system rotating in the direction, the fundamental wave antiphase of the two phase alternating current extracted by the filter means is converted into the fundamental antiphase of the two phase alternating current in the biaxial stationary coordinate system. It can comprise by providing the 2nd rotation coordinate transformation part reversely converted into minute. In this case, the fundamental wave reverse phase component of the two-phase alternating current obtained from the second rotational coordinate conversion unit may be used as the detection output of the fundamental wave antiphase component detection unit. You may make it use the fundamental wave antiphase part of the three-phase alternating current obtained by carrying out 2 phase / 3 phase conversion of an antiphase part as a detection output of a fundamental wave antiphase part detection part.
[0022]
The three-phase / two-phase conversion unit, the first rotation coordinate conversion unit, the filter means, the second rotation coordinate conversion unit, and the ground fault determination unit are a computer and a predetermined program to be executed by the computer And can be realized.
[0023]
In the present invention, the calculation for detecting the antiphase component of the three-phase unbalanced current is performed by calculating the vector operators a [= exp {j (2π / 3)}] and a on the currents of the three phases. ² It is also possible to use a symmetric coordinate method for obtaining an antiphase component by multiplying by.
[0024]
However, in order to obtain the antiphase component of the three-phase unbalanced current by the symmetric coordinate method, the vector operators a and a ² Since the phase shift calculation for multiplying and the averaging process of each phase current are required, the time required for the calculation becomes long, and it is inevitable that it takes time to detect the reverse phase.
[0025]
On the other hand, as described above, if the antiphase component is obtained by the coordinate transformation method, the calculation can be completed in a relatively short time, and therefore the antiphase component can be detected at high speed. It is possible to easily and quickly detect the change of the phase current every moment.
[0026]
In the present invention, when the fundamental wave antiphase component of the two-phase alternating current obtained from the second rotational coordinate converter is used as the detection output of the fundamental wave antiphase component detector, the three-phase unbalanced current The aspect cannot be verified. However, if only the detection of the occurrence of a ground fault in the circuit on the high voltage distribution line side is performed, the fundamental wave antiphase component of the two-phase alternating current obtained from the second rotating coordinate conversion unit is converted to the fundamental wave antiphase component. There is no problem even if it is used as the detection output of the minute detection unit.
[0027]
The fundamental phase of the three-phase alternating current obtained by performing the two-phase / three-phase transformation of the fundamental phase of the two-phase alternating current obtained from the second rotational coordinate transformation unit When used as a detection output, when a ground fault occurs in the circuit on the high-voltage distribution line side, not only can the ground fault be detected, but also a three-phase imbalance flowing through the power receiving transformer. It is also possible to verify the current mode.
[0028]
The three-phase AC detection unit can be configured by a current transformer attached to a low-voltage circuit of a power receiving transformer, for example. Usually, in a power receiving / distributing facility such as a network power receiving / distributing facility, a circuit on a low voltage side of the power receiving transformer Since the current transformer is provided, the above-described three-phase alternating current detection unit can be configured using the existing current transformer.
[0029]
The power distribution facility according to the present invention includes a power receiving transformer composed of an insulating transformer in which a high voltage side is connected to a high voltage distribution line drawn from a power substation, and a high voltage side circuit or a low voltage side circuit of the power receiving transformer. A circuit breaker that opens and closes the circuit, and is provided in a circuit on the low voltage side of the power receiving transformer to detect a three-phase alternating current flowing through the power receiving transformer, and is detected by the current transformer. In addition, a fundamental wave antiphase component detecting unit for detecting the antiphase component of the fundamental wave of the three-phase AC current, and a circuit on the high voltage distribution line side connected to the receiving transformer from the antiphase component detected by the fundamental wave antiphase component detecting unit A ground fault determination unit that determines whether or not a ground fault has occurred, and a circuit breaker control unit that gives a circuit breaker command to the circuit breaker when the ground fault determination unit determines that a ground fault has occurred. It is characterized by that.
[0030]
The power distribution facility is provided in common with a plurality of network transformers composed of insulation transformers each having a high voltage side connected to a plurality of high voltage distribution lines drawn from a power substation, and the plurality of network transformers. A network power receiving / distribution facility including a network bus provided and a network protector provided between the low voltage side of each network transformer and the network bus is widely used. The network protector corresponds to a protector breaker provided between the low-voltage side of the corresponding network transformer and the network bus, and a current transformer that detects the current flowing through the circuit on the low-voltage side of the corresponding network transformer. When a network relay is provided that gives a breaker command to the protector breaker when it detects that a reverse power flow has occurred from the low voltage side to the high voltage side of the network transformer, and the network relay detects a reverse power flow Shut off the protector circuit breaker.
[0031]
When the present invention is applied to such a network power receiving / distributing facility, a fundamental wave antiphase component detecting unit for detecting an antiphase component of the fundamental wave of the three-phase alternating current detected by the current transformer, and the fundamental wave A ground fault determination unit that determines whether or not a ground fault has occurred in the circuit connected to the corresponding network transformer from the reverse phase detected by the reverse phase detection unit, and the ground fault determination unit has a ground fault The network protector is provided with a circuit breaker control unit that gives a break command to the protector circuit breaker when it is determined.
[0032]
If a ground fault detector is installed in the network power distribution facility as described above, it is possible to detect a ground fault in the circuit on the high voltage distribution line in the power distribution facility. By disconnecting the high voltage side circuit and the low voltage side circuit of the power receiving transformer connected to the distribution line, it becomes possible to quickly take measures such as stopping the power supply to the high voltage distribution line where the accident occurred.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
A configuration example of a ground fault detection apparatus according to the present invention will be described below with reference to the drawings.
[0034]
FIG. 4 shows an example of the configuration of a distribution system to which the present invention is applied. In FIG. 4, reference numeral 1 denotes a transformer 1A1 to 1A3 and a transformer 1A1 to 1A3 each having a high voltage side connected to a power plant 2 through a transmission line. It is a power supply side substation provided with bus-bar 1B1-1B3 connected to the low voltage | pressure side of this.
[0035]
High voltage distribution lines 3a to 3c are connected to the buses 1B1 to 1B3 of the substation 1 through circuit breakers 1C1 to 1C3, respectively. A high-voltage distribution line 3d is further connected to the bus 1B3 through a circuit breaker 1C4. In this example, an extra high voltage of 20 KV class is applied to the distribution lines 3a to 3d from the transformers 1A1 to 1A3 through the buses 1B1 to 1B3 and the circuit breakers 1C1 to 1C4.
[0036]
Although not shown, the power substation 1 has an overcurrent relay (OC) that trips the circuit breakers 1C1 to 1c4 when the current flowing through the distribution lines 3a to 3d exceeds the limit value, and the high voltage distribution lines 3a to 3c. A ground fault relay (GR) that trips the circuit breakers 1c1 to 1C3 when a ground fault occurs is provided.
[0037]
In the illustrated example, the network power distribution facility 4 according to the present invention is connected to the high voltage distribution lines 3a to 3c. This power distribution facility includes network transformers 4Ba to 4Bc whose high voltage side is connected to high voltage distribution lines 3a to 3c through disconnectors 4Aa to 4Ac, respectively, and one end through protector fuses 4Ca to 4Cc on the low voltage side of transformers 4Ba to 4Bc. Are connected to the other ends of the circuit breakers 4Da to 4Dc, and circuit breaker control units 4Ea to 4Ec for controlling the circuit breakers 4Da to 4Dc. Current transformers 4Fa-4Fc are attached to the low voltage side circuits of the transformers 4Ba-4Bc, and the three-phase AC signals detected by these current transformers are given to the circuit breaker controllers 4Ea-4Ec. Yes. The circuit breaker controllers 4Ea to 4Ec are also supplied with the low-voltage side voltages of the network transformers 4Ba to 4Bc.
[0038]
Each of the circuit breaker control units 4Ea to 4Ec is provided with a network relay, and the network transformers 4Ba to 4Bc are more than a threshold value from the low voltage side to the high voltage side (from the network bus side BUS1 to the high voltage distribution lines 3a to 3c side). When reverse power flow occurs, the protector breakers 4Da to 4Dc are tripped.
[0039]
A voltage (for example, 400 V) obtained by stepping down the extra high voltage (22 KV) of the high-voltage distribution lines 3a to 3c by the network transformers 4Ba to 4Bc is applied to the network bus BUS1.
[0040]
In the illustrated example, the protector fuse 4Ca, the protector circuit breaker 4Da, the current transformer 4Fa, and the circuit breaker control unit 4Ea constitute the network protector 4Ga, and the protector fuse 4Cb, the protector circuit breaker 4Db, the current transformer 4Fb, and the circuit breaker control. The network protector 4Gb is configured by the unit 4Eb. The protector circuit breaker 4Dc, the current transformer 4Fc, and the circuit breaker control unit 4Ec constitute a network protector 4Gc.
[0041]
In the illustrated example, in addition to the network power distribution facility according to the present invention, as a power distribution facility using the ground fault detection device according to the present invention, a common standby power distribution facility 5 in which a distributed power source is connected to the low voltage side. Is connected to the high voltage distribution lines 3a and 3b. This power distribution facility includes a power receiving transformer 5B whose high voltage side is connected to distribution lines 3a and 3b via circuit breakers 5Aa and 5Ab, respectively, and a busbar connected to the low voltage side of power receiving transformer 5B through circuit breaker 5C. BUS2, current transformer 5D attached to the circuit on the low voltage side of transformer 5B, and the output of current transformer 5D and the voltage on the low voltage side of transformer 5B as inputs, from the low voltage side of transformer 5B to the high voltage side And a circuit breaker control unit 5E having a relay that trips the circuit breaker 5C when it is detected that a reverse power flow has occurred. A voltage (for example, 6000 V) obtained by stepping down an extra high voltage with the transformer 5B is applied to the bus BUS2.
[0042]
In the illustrated example, the high-voltage side of the distribution line transformer Tr is connected to the network bus BUS1 through the switch SW0, and the loads A1 to A4 are connected through the switches SW1 to SW4. Loads A5 and A6 are connected to the bus BUS2 of the standby standby power distribution facility 5, and a load A7 of 22 [KV] is connected to the high voltage distribution line 3d.
[0043]
Further, distributed power sources G1 and G2 are connected to the network bus BUS1 and the bus BUS2 of the regular standby power distribution facility, respectively.
[0044]
Although not shown in FIG. 4, various power receiving / distribution facilities such as a power distribution tower and a distributed power source may be further connected to the power distribution system.
[0045]
In the distribution system as shown in FIG. 4, for example, when a ground fault occurs at point X of the high-voltage distribution line 3a, the ground fault protective relay provided at the substation 1 causes an accident with the transformer 1A1. The circuit breaker 1c1 provided between the high voltage distribution line 3a and the high voltage distribution line 3a performs a breaking operation, and the distribution line 3a in which the ground fault has occurred is disconnected from the transformer 1A1 of the substation. At this time, from the healthy high-voltage distribution line 3b and 3c side, the circuit in the network power distribution facility 4 (disconnector 4Ab-network transformer 4Bb-breaker 4Db circuit and disconnector 4Ac-network transformer 4Bc-breaker 4Dc Circuit) and the network bus BUS1, current flows into the network transformer 4Ba connected to the high voltage distribution line 3a where the accident occurred, and a reverse power flow is generated from the low voltage side to the high voltage side of the transformer 4Ba. At this time, the network relay provided in the circuit breaker control unit 4Ea combines the exciting current of the transformer 4Ba and the charging current flowing from the network bus BUS1 side through the transformer 4Ba to the ground capacitance C of the high-voltage distribution line 3a. The current and the voltage on the low voltage side of the transformer 4Ba are detected to detect the reverse power flow, and the protector breaker 4Da is opened.
[0046]
In the network power receiving / distributing facility 4 shown in FIG. 4, if the threshold value of the network relay with respect to the reverse power is set low, the distributed power source G1 is connected to the high voltage distribution lines 3a to 3c in a state where no ground fault has occurred. The protector circuit breakers 4Da to 4Dc also perform a breaking operation when a reverse power flow occurs on the distribution lines 3a to 3c through the network bus BUS1 and the network transformers 4Ba to 4Bc.
[0047]
As described above, it is necessary to avoid the circuit breaker in the network power distribution / distribution equipment 4 from performing a shut-off operation in response to a reverse power flow in a steady state. Therefore, as shown in FIG. 4, when the distributed power supply is connected to the system, the threshold value of the relay that detects the reverse power flow in the power distribution facility 4 is set high, It is necessary to suppress the operation of the circuit breaker in the power distribution facility, and when a ground fault occurs on the high voltage distribution lines 3a to 3c, it becomes impossible to disconnect the line connected to the high voltage distribution line where the accident occurred. Sometimes. In order to prevent such a situation from occurring, a ground fault detection device for detecting a ground fault in the high voltage distribution line is provided in the network power distribution facility 4, and the ground of the high voltage distribution line is detected by the ground fault detection device. What is necessary is just to isolate | separate the high voltage side circuit and low voltage side circuit of a network transformer when a fault is detected.
[0048]
FIG. 1 shows an overall configuration of a ground fault detection apparatus according to the present invention. In FIG. 1, 10u to 10w are isolation transformers (in the example of FIG. 4B to 4Bc) are U, V, W three-phase circuits on the low-pressure side, and current transformers CTau, CTav, and CTaw are attached to these circuits. When a current transformer (for example, current transformers 4Fa to 4Fc in FIG. 4) is already provided in the circuit on the low voltage side of the insulation transformer as in the network power distribution facility, the existing current transformer is changed. It can be used as the flow devices CTau to CTaw. In the example shown in FIG. 1, the current transformers CTau, CTav, and CTaw constitute a three-phase alternating current detection unit 11 that detects a three-phase alternating current flowing through a circuit on the low voltage side of the insulation transformer. The detected value of the three-phase alternating current obtained from the unit 11 is given to the fundamental wave reverse phase detection unit 12.
[0049]
The fundamental wave anti-phase component detection unit 12 is a part that detects the anti-phase component of the unbalanced three-phase AC current by the coordinate transformation method. The fundamental wave anti-phase component detection unit 12 is detected by the three-phase AC detection unit 11. Three-phase / 2 that treats a three-phase alternating current as a vector quantity in a three-axis stationary coordinate system and converts the three-phase alternating current in the three-axis stationary coordinate system into a two-phase alternating current in a two-axis stationary coordinate system in which the two axes are orthogonal to each other The phase converter 13 and the biaxial stationary coordinate system are transformed into a first biaxial rotational coordinate system that rotates in the phase rotation direction of the fundamental wave normal phase or the phase rotation direction of the fundamental wave antiphase of the two-phase alternating current. Thus, one of the fundamental wave positive phase component and the fundamental wave antiphase component of the two-phase alternating current obtained by the three-phase / two-phase conversion unit 13 is converted into a direct current, and the other is an alternating current having a frequency twice the fundamental wave frequency. A first rotation coordinate conversion unit 14 for converting into an electric current and an output of the first rotation coordinate conversion unit 14; Filter means 15 for extracting the fundamental wave anti-phase component by removing the fundamental wave normal phase component of the two-phase alternating current from the first biaxial rotational coordinate system in the opposite direction to the first biaxial rotational coordinate system By converting to the rotating second biaxial rotating coordinate system, the two-phase alternating current in the biaxial stationary coordinate system in the biaxial stationary coordinate system is converted from the fundamental wave antiphase component of the two-phase alternating current extracted by the filter means 15. A second rotating coordinate conversion unit 16 that performs reverse conversion to the fundamental wave anti-phase component of the two-phase, and two-phase to obtain the fundamental wave anti-phase component of the three-phase alternating current by performing two-phase / three-phase conversion of the fundamental two-phase alternating current / 3-phase converter 17. The fundamental phase reverse phase portion of the three-phase alternating current obtained from the two-phase / three-phase converter 17 is given to the ground fault determination unit 18 that determines whether or not a ground fault has occurred. The fundamental antiphase component detection unit 12 and the ground fault determination unit 18 are realized by a microcomputer and a predetermined program to be executed by the microcomputer.
[0050]
The three-phase / two-phase conversion unit 13 converts the three-phase alternating current in the three-axis stationary coordinate system detected by the three-phase alternating current detection unit 11 into the two-phase alternating current in the two-axis stationary coordinate system in which the two axes are orthogonal to each other. As shown in FIG. 2, in the three-axis stationary coordinate system in which the three axes U, V, and W intersect with each other at an angular interval of 120 degrees on the plane, the two-axis stationary where the two axes α and β are orthogonal Signals of three-phase alternating currents Iu, Iv, and Iw (a dot indicating a vector amount is omitted in the text) of a three-axis stationary coordinate system are performed by performing a conversion to the coordinate system (three-phase / two-phase conversion). Is converted into signals of two-phase alternating currents Iα and Iβ in a biaxial stationary coordinate system. As shown in FIG. 2, when the angle formed by the three-axis stationary coordinate and the two-axis stationary coordinate is δ, the calculation of the three-phase / two-phase conversion is as follows:
[0051]
[Expression 1]

Here, when the α axis and the β axis are determined so that δ = 0, the above equation is expressed by the following equation [Equation 2].
[0052]
[Expression 2]

Further, the current (Iu, Iv, Iw) of the formula [Equation 2] is obtained by a symmetric coordinate method using a zero-phase current I0, a positive-phase current I1, a negative-phase current I2, and a vector operator a and a ² And [Expression 3] below.
[0053]
[Equation 3]

Here, if the zero-phase current is ignored, I0 = 0, so the equation of [Equation 3] becomes the following [Equation 4].
[0054]
[Expression 4]

Substituting the equation of [Equation 4] into the equation of [Equation 2], the equation for obtaining Iα and Iβ is as shown in the following [Equation 5].
[0055]
[Equation 5]

Here, when the determinant of [Equation 5] is expanded to obtain an equation for calculating Iα, the following [Equation 6] is obtained.
[0056]
[Formula 6]

Vector operators a and a ² Are the following [Equation 7] and [Equation 8], respectively.
[0057]
[Expression 7]

[Equation 8]

Substituting the equations of [Equation 7] and [Equation 8] into the equation of [Equation 6], the current Iα is given by the following equation [Equation 9].
[0058]
[Equation 9]

As shown in FIG. 3, if the angle formed by the reference voltage V1 and the positive phase current I1 is Φ and the angle formed by the reference voltage V1 and the negative phase current I2 is θ, then I1 (vector) = I1 ε ^{j (ωt + Φ)} , I2 (vector) = I2 ε ^{j (ωt + θ)} The current Iα is given by the following [Equation 10].
[0059]
[Expression 10]

Similarly, the current Iβ is obtained from the following equation [Equation 11].
[0060]
[Expression 11]

By causing the computer to perform the calculations of the above equations [Equation 10] and [Equation 11], three-phase / two-phase conversion is performed to obtain two-phase alternating currents Iα and Iβ in the two-axis stationary coordinate system.
[0061]
Next, the first rotating coordinate conversion unit 14 performs phase rotation in the biaxial stationary coordinate system of α and β in the phase rotation direction of the fundamental wave normal phase or the phase rotation direction of the fundamental wave reverse phase of the two-phase alternating current. The fundamental wave positive phase component and the fundamental wave antiphase component of the two-phase alternating currents Iα and Iβ obtained by the three-phase / two-phase conversion unit 13 by converting the first two-axis rotating coordinate system that rotates at the same speed as the velocity. Is converted into a DC component, and the other is converted into a frequency component twice the fundamental frequency. Here, when the first biaxial rotating coordinate system is rotated in the same direction as the phase rotation direction of the fundamental wave positive phase at the same speed as the fundamental wave positive phase component, the fundamental wave positive phase component appears as a DC component, The fundamental wave anti-phase component appears as a component having a frequency twice that of the fundamental wave. When the first biaxial rotating coordinate system is rotated in the same direction as the phase rotation direction of the fundamental wave anti-phase and at the same speed as the anti-phase component, the fundamental wave normal phase component has a frequency twice the fundamental wave frequency. It appears as a component, and the fundamental wave antiphase component appears as a direct current component.
[0062]
The rotation direction of the first biaxial rotational coordinate system may be any direction, but in the following description, the rotational direction of the first biaxial rotational coordinate system is the same as the phase rotational direction of the fundamental wave anti-phase component. It is assumed that (the direction opposite to the rotation direction of the voltage vector of the distribution system).
[0063]
In other words, an α, β orthogonal two-axis stationary coordinate system of two-phase currents Iα and Iβ (both vector quantities) converted in two phases is orthogonally rotated in the opposite direction to the voltage vector of the distribution system at the same speed as the voltage vector. Conversion into two-phase currents Ip and Iq (vector quantities) in a biaxial rotating coordinate system. The conversion formula from the orthogonal two-axis stationary coordinate system to the orthogonal two-axis rotational coordinate system is as follows:
[0064]
[Expression 12]

When this determinant is opened to obtain the current Ip of the rotating coordinate system, the following [Equation 13] is obtained.
[0065]
[Formula 13]

Similarly, the current Iq of the rotating coordinate system is obtained from the following [Equation 14].
[0066]
[Expression 14]

The first term of the currents Ip and Iq in the rotating coordinate system is the positive phase current I1, which is an AC component of the angular velocity 2ωt. The second term is the reverse-phase component current I2, and this reverse-phase component current I2 has no time factor and thus becomes a direct current component.
[0067]
The filter means 15 of FIG. 1 is composed of a low-pass filter, and extracts an antiphase component current in the p, q2 axis rotation coordinate system by removing an alternating current component (positive phase current) from the Ip and Iq.
[0068]
The p-axis component Ip-DC of the reversed-phase component current in the p, q2 axis rotation coordinate system is expressed by the following equation [Equation 15].
[0069]
[Expression 15]

Further, the q-axis component Iq-DC of the reversed-phase component current in the p, q2-axis rotating coordinate system is expressed by the following equation [Equation 16].
[0070]
[Expression 16]

The second rotational coordinate conversion unit 16 converts the p and q two-axis rotational coordinate system (first two-axis rotational coordinate system) into the first procedure by a procedure reverse to the arithmetic processing performed by the first rotational coordinate conversion unit 14. The two-phase reversed phase extracted by the filter means 15 is converted into a second two-axis rotating coordinate system that rotates in the opposite direction to the two-axis rotating coordinate system at the same speed as the first two-axis rotating coordinate system. The divided current (two-phase alternating current having the antiphase components Ip-DC and Iq-DC in [Equation 15] and [Equation 16] above) is converted into the fundamental antiphase component of the two-phase alternating current in the α, β2 axis stationary coordinate system. Convert back to.
[0071]
The two-phase / three-phase converter 17 converts the fundamental phase of the two-phase alternating current obtained from the second rotational coordinate converter 16 in the reverse order of the process performed by the three-phase / 2-phase converter 13. Converts to the three-phase AC current in the three-axis stationary coordinate system with the opposite phase of the fundamental wave (the three-phase AC currents Iu, Iv, and Iw detected from the low-voltage circuit of the power receiving transformer). .
The ground fault determination unit 18 determines whether or not a ground fault has occurred from the negative phase detected by the fundamental wave negative phase detection unit 12. In order to determine the presence or absence of a ground fault from the negative phase component detected by the fundamental wave negative phase component detection unit 12, for example, the negative phase component is detected at regular intervals and detected at each detection time. The amount of change in the reverse phase is detected by taking the difference between the detected reverse phase and the previously detected reverse phase, and when the detected amount of change in the reverse phase exceeds the predetermined judgment value It may be determined that a ground fault has occurred.
[0072]
Further, a predetermined determination criterion may be set for the reverse phase component detected at any time, and it may be determined that a ground fault has occurred when the detected reverse phase component is equal to or greater than the determination criterion. .
[0073]
In the above example, the first rotating coordinate conversion unit 14 rotates the biaxial rotating coordinate system in the same direction as the phase rotating direction of the reverse phase included in the system voltage. You may make it rotate in the same direction as the phase rotation direction for the positive phase contained in a voltage. In this case, since the reverse phase current is obtained as a signal having a frequency twice as high as the fundamental wave frequency, the filter means 15 is constituted by a high-pass filter.
[0074]
In the above example, in the fundamental wave antiphase component detection unit 12, the antiphase component of the two phase AC current obtained by the second rotational coordinate conversion unit 16 is converted into the antiphase of the three phase AC current by the two phase / 3 phase conversion unit. In this way, when a ground fault occurs in the external circuit, not only can the ground fault be detected, but also the three-phase unbalance flowing through the power receiving transformer. It is also possible to verify the current mode.
[0075]
If only the detection of the occurrence of the ground fault in the external circuit is performed, the fundamental wave antiphase component of the two-phase alternating current obtained from the second rotating coordinate converter 16 is converted into the fundamental wave antiphase component detector. Since there is no problem even if it is used as a detection output, the 2-phase / 3-phase converter 17 can be omitted.
[0076]
In the example shown in FIG. 1, a ground fault detection device according to the present invention is configured by the three-phase AC detection unit 11, the fundamental wave antiphase component detection unit 12, and the ground fault determination unit 18.
[0077]
When the present invention is applied to the power distribution system shown in FIG. 4, the fundamental wave antiphase component detection unit 12 and the ground fault determination unit 18 shown in FIG. 1 are provided in each of the network protectors 4Ga to 4Gc, and the network When it is determined that a ground fault has occurred in the high voltage distribution lines 3a to 3c by the ground fault determination unit 18 provided in each of the protectors 4Ga to 4Gc, the circuit breaker control units 4Ea to 4Ec are respectively connected to the circuit breakers 4Da to 4Dc. A shutoff command is given to.
[0078]
Similarly, the basic standby anti-distribution facility 5 is also provided with a fundamental antiphase component detection unit 12 and a ground fault determination unit 18, and the ground fault determination unit 18 determines that a ground fault has occurred on the high voltage distribution line side. The circuit breaker control unit 5E is configured to give a circuit break command to the circuit breaker 5C. In place of the circuit breaker 5C, a circuit break command may be given to the circuit breaker 5Aa or 5Ab.
[0079]
With the above configuration, for example, when a ground fault occurs at the point X in FIG. 4 and the high-voltage distribution line 3a is disconnected from the bus 1B1 of the substation 1, the network power distribution facility has the circuit breaker control unit 4Ea. In order to detect that a ground fault has occurred in the high-voltage distribution line 3a, the protector circuit breaker 4Da is opened, and the high-voltage side circuit and the low-voltage side circuit of the transformer 4Ba are disconnected. Thereby, it is possible to prevent a reverse power flow from occurring on the high voltage distribution line 3a side from the other healthy distribution lines 3b and 3c side through the transformers 4Bb and 4Bc, the network bus BUS1 and the transformer 4Ba.
[0080]
In the case of the construction of the standby standby power distribution facility as described above, for example, when a ground fault occurs at point X in FIG. 4 and the high voltage distribution line 3a is disconnected from the bus 1B1 of the substation 1, the circuit breaker control is performed. In order for the ground fault determination part provided in the part 5E to detect that a ground fault has occurred in the high voltage distribution line 3a, the circuit breaker 5C is opened, and the high voltage side circuit and the low voltage side circuit of the transformer 5B are disconnected. As a result, it is possible to prevent a reverse power flow from occurring on the high-voltage distribution line 3a side from the distributed power source G2 through the bus BUS2 and the transformer 5B.
[0081]
The ground fault detection apparatus according to the present invention can be applied to, for example, a power receiving / distributing facility connected to a distributed power source on the low voltage side, or a power receiving / distributing facility connected to another power distribution system.
[0082]
【The invention's effect】
As described above, according to the present invention, it is possible to detect that a ground fault has occurred in the high-voltage distribution line connected to the low-voltage circuit of each power receiving transformer provided in the distribution system. Therefore, while responding to the request to simplify the circuit configuration between the power receiving transformer and the high voltage distribution line, each power distribution facility detects a ground fault in the high voltage distribution line and There is an advantage that measures such as disconnecting the line connected to the electric wire from the high-voltage distribution line can be taken.
[0083]
If the power distribution facility is configured as in the present invention, a ground fault in the circuit on the high voltage distribution line side can be detected in the power distribution facility, which leads to the high voltage distribution line in which the ground fault is detected. The high voltage side circuit and the low voltage side circuit of the power receiving transformer can be separated to quickly take measures such as stopping the power supply to the high voltage distribution line where the accident occurred.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration example of a ground fault detection apparatus according to the present invention.
FIG. 2 is a vector diagram used for explaining a ground fault detection apparatus according to the present invention.
FIG. 3 is a vector diagram used to explain a ground fault detection apparatus according to the present invention.
FIG. 4 is a circuit diagram showing a configuration example of a power distribution system to which the present invention is applied.
[Explanation of symbols]
1 Power substation
3a-3d Distribution line
4 Network power distribution facilities
4Aa ～ 4Ac Disconnector
4Ba-4Bc network transformer
4Da ~ 4Dc protector circuit breaker
4Ea ~ 4Ec Circuit breaker controller
BUS1 network bus
11 Three-phase AC detector
12 Fundamental phase detector
18 Ground fault judgment part

Claims (5)

電源変電所から引き出された高圧配電線に絶縁変圧器からなる受電用変圧器を備えた受配電設備が接続されている配電系統の前記高圧配電線で地絡事故が生じたことを前記受配電設備で検出する地絡検出装置において、
前記受電用変圧器の低圧側の回路を流れる３相交流電流を検出する３相交流検出部と、
前記３相交流検出部により検出された３相交流電流の基本波の逆相分を検出する基本波逆相分検出部と、
前記基本波逆相分検出部により検出された逆相分から地絡事故の発生の有無を判定する地絡判定部と、
を具備したことを特徴とする配電系統の地絡検出装置。The fact that a ground fault has occurred in the high-voltage distribution line of the distribution system in which the high-voltage distribution line drawn from the power supply substation is connected to the distribution system equipped with a power receiving transformer consisting of an insulating transformer. In the ground fault detection device to detect with equipment,
A three-phase alternating current detecting unit for detecting a three-phase alternating current flowing through a circuit on the low voltage side of the power receiving transformer;
A fundamental wave antiphase component detection unit for detecting an antiphase component of the fundamental wave of the three phase AC current detected by the three phase AC detector;
A ground fault determination unit that determines whether or not a ground fault has occurred from the negative phase component detected by the fundamental phase detection unit;
A ground fault detection device for a power distribution system. 前記基本波逆相分検出部は、
前記３相交流検出部により検出された３相交流電流を３軸静止座標系におけるベクトル量として扱って該３軸静止座標系における３相交流電流を、２軸が互いに直交する２軸静止座標系における２相交流電流に変換する３相／２相変換部と、
前記２軸静止座標系を前記２相交流電流の基本波正相分の相回転方向または基本波逆相分の相回転方向に回転する第１の２軸回転座標系に変換することにより前記２相交流電流の基本波正相分及び基本波逆相分の一方を直流電流に変換し、他方を基本波周波数の２倍の周波数の交流電流に変換する第１の回転座標変換部と、
前記第１の回転座標変換部の出力から２相交流電流の基本波正相分を除去して基本波逆相分を抽出するフィルタ手段と、
前記第１の２軸回転座標系を該第１の２軸回転座標系と逆方向に回転する第２の２軸回転座標系に変換することにより、前記フィルタ手段により抽出された２相交流電流の基本波逆相分を２軸静止座標系における２相交流電流の基本波逆相分に逆変換する第２の回転座標変換部とを備え、
前記第２の回転座標変換部から得られる２相交流電流の基本波逆相分、または該２相交流電流の基本波逆相分を２相／３相変換することにより得た３相交流電流の基本波逆相分を前記基本波逆相分検出部の検出出力として用いることを特徴とする請求項１に記載の地絡検出装置。The fundamental wave antiphase component detecting unit is
A three-phase alternating current detected by the three-phase alternating current detection unit is treated as a vector quantity in a three-axis stationary coordinate system, and a three-phase alternating current in the three-axis stationary coordinate system is converted into a two-axis stationary coordinate system in which two axes are orthogonal to each other. A three-phase / two-phase converter for converting into a two-phase alternating current in
By converting the biaxial stationary coordinate system into a first biaxial rotational coordinate system that rotates in the phase rotation direction of the fundamental wave normal phase or the phase rotation direction of the fundamental wave antiphase of the two-phase alternating current. A first rotating coordinate conversion unit that converts one of the fundamental phase and the fundamental phase of the phase alternating current into a direct current and the other into an alternating current having a frequency twice the fundamental frequency;
Filter means for extracting a fundamental wave anti-phase component by removing a fundamental wave normal phase component of a two-phase alternating current from an output of the first rotational coordinate converter;
The two-phase alternating current extracted by the filter means by converting the first two-axis rotating coordinate system into a second two-axis rotating coordinate system that rotates in the opposite direction to the first two-axis rotating coordinate system. A second rotating coordinate conversion unit that reversely converts the fundamental wave anti-phase component of the fundamental wave to the fundamental wave anti-phase component of the two-phase alternating current in the biaxial stationary coordinate system,
A three-phase alternating current obtained by performing a two-phase / three-phase conversion on the fundamental wave anti-phase portion of the two-phase alternating current obtained from the second rotational coordinate conversion unit or the fundamental wave anti-phase portion of the two-phase alternating current. The ground fault detection device according to claim 1, wherein the fundamental wave negative phase component is used as a detection output of the fundamental wave negative phase detection unit. 電源変電所から引き出された高圧配電線に高圧側が接続された絶縁変圧器からなる受電用変圧器と該受電用変圧器の高圧側の回路または低圧側の回路を開閉する遮断器とを備えた受配電設備において、
前記受電用変圧器の低圧側の回路に設けられて該受電用変圧器を通して流れる３相交流電流を検出する変流器と、
前記変流器により検出された３相交流電流の基本波の逆相分を検出する基本波逆相分検出部と、
前記基本波逆相分検出部により検出された逆相分から前記受電用変圧器につながる前記高圧配電線側の回路で地絡事故が発生したか否かを判定する地絡判定部と、
前記地絡判定部が地絡事故が発生したと判定した時に前記遮断器に遮断指令を与える遮断器制御部と、
を具備したことを特徴とする受配電設備。A power receiving transformer comprising an insulating transformer having a high voltage side connected to a high voltage distribution line drawn from a power substation, and a circuit breaker for opening and closing the high voltage side circuit or the low voltage side circuit of the power receiving transformer. In power distribution facilities
A current transformer provided in a circuit on a low-voltage side of the power receiving transformer to detect a three-phase alternating current flowing through the power receiving transformer;
A fundamental antiphase component detector for detecting the antiphase component of the fundamental wave of the three-phase alternating current detected by the current transformer;
A ground fault determination unit that determines whether a ground fault has occurred in the circuit on the high-voltage distribution line side connected to the power receiving transformer from the negative phase component detected by the fundamental wave negative phase detection unit;
A circuit breaker control unit that gives a circuit break command to the circuit breaker when the ground fault determination unit determines that a ground fault has occurred;
A power distribution facility characterized by comprising: 電源変電所から引き出された複数の高圧配電線にそれぞれ高圧側が接続された絶縁変圧器からなる複数のネットワーク変圧器と、前記複数のネットワーク変圧器に対して共通に設けられたネットワーク母線と、各ネットワーク変圧器の低圧側と前記ネットワーク母線との間に設けられたネットワークプロテクタとを備え、
前記ネットワークプロテクタは、対応するネットワーク変圧器の低圧側と前記ネットワーク母線との間に設けられたプロテクタ遮断器と、対応するネットワーク変圧器の低圧側の回路を流れる電流を検出する変流器と、対応するネットワーク変圧器の低圧側から高圧側に逆電力の潮流が生じたことを検出した時に前記プロテクタ遮断器を開くネットワーク継電器とを備えている受配電設備において、
前記ネットワークプロテクタは、
前記変流器が検出した３相交流電流の基本波の逆相分を検出する基本波逆相分検出部と、
前記基本波逆相分検出部が検出した逆相分から対応するネットワーク変圧器につながる前記高圧配電線側の回路で地絡事故が発生したか否かを判定する地絡判定部と、
前記地絡判定部が地絡事故が発生したと判定したときに前記プロテクタ遮断器に遮断指令を与える遮断器制御部と、
を具備したことを特徴とする受配電設備。A plurality of network transformers composed of insulating transformers each having a high voltage side connected to a plurality of high voltage distribution lines drawn out from a power substation; a network bus provided in common to the plurality of network transformers; and A network protector provided between the low-voltage side of the network transformer and the network bus;
The network protector includes a protector breaker provided between a low voltage side of a corresponding network transformer and the network bus, a current transformer that detects a current flowing through a circuit on the low voltage side of the corresponding network transformer, In a power distribution facility comprising a network relay that opens the protector breaker when detecting that a reverse power flow has occurred from the low voltage side to the high voltage side of the corresponding network transformer,
The network protector
A fundamental wave anti-phase component detector for detecting the anti-phase component of the fundamental wave of the three-phase alternating current detected by the current transformer;
A ground fault determination unit that determines whether or not a ground fault has occurred in the circuit on the high-voltage distribution line side connected to the corresponding network transformer from the negative phase component detected by the fundamental wave negative phase detection unit;
A circuit breaker control unit that gives a break command to the protector breaker when the ground fault determination unit determines that a ground fault has occurred;
A power distribution facility characterized by comprising: 前記基本波逆相分検出部は、
前記変流器により検出された３相交流電流を３軸静止座標系におけるベクトル量として扱って該３軸静止座標系の３相交流電流を、２軸が互いに直交する２軸静止座標系における２相交流電流に変換する３相／２相変換部と、
前記２軸静止座標系を前記２相交流電流の基本波正相分の相回転方向または基本波逆相分の相回転方向に回転する第１の２軸回転座標系に変換することにより前記２相交流電流の基本波正相分及び基本波逆相分の一方を直流電流に変換し、他方を基本波周波数の２倍の周波数の交流電流に変換する第１の回転座標変換部と、
前記第１の回転座標変換部の出力から２相交流電流の基本波正相分を除去して基本波逆相分を抽出するフィルタ手段と、
前記第１の２軸回転座標系を該第１の２軸回転座標系と逆方向に回転する第２の２軸回転座標系に変換することにより、前記フィルタ手段により抽出された２相交流電流の基本波逆相分を２軸静止座標系における２相交流電流の基本波逆相分に逆変換する第２の回転座標変換部とを備え、
前記第２の回転座標変換部から得られる２相交流電流の基本波逆相分、または該２相交流電流の基本波逆相分を２相／３相変換することにより得た３相交流電流の基本波逆相分を前記基本波逆相分検出部の検出出力として用いることを特徴とする請求項３または４に記載の受配電設備。The fundamental wave antiphase component detecting unit is
The three-phase alternating current detected by the current transformer is treated as a vector quantity in the three-axis stationary coordinate system, and the three-phase alternating current in the three-axis stationary coordinate system is converted to 2 in the two-axis stationary coordinate system in which the two axes are orthogonal to each other. A three-phase / two-phase converter for converting into a phase alternating current;
By converting the biaxial stationary coordinate system into a first biaxial rotational coordinate system that rotates in the phase rotation direction of the fundamental wave normal phase or the phase rotation direction of the fundamental wave antiphase of the two-phase alternating current. A first rotating coordinate conversion unit that converts one of the fundamental phase and the fundamental phase of the phase alternating current into a direct current and the other into an alternating current having a frequency twice the fundamental frequency;
Filter means for extracting a fundamental wave anti-phase component by removing a fundamental wave normal phase component of a two-phase alternating current from an output of the first rotational coordinate converter;
The two-phase alternating current extracted by the filter means by converting the first two-axis rotating coordinate system into a second two-axis rotating coordinate system that rotates in the opposite direction to the first two-axis rotating coordinate system. A second rotating coordinate conversion unit that reversely converts the fundamental wave anti-phase component of the fundamental wave to the fundamental wave anti-phase component of the two-phase alternating current in the biaxial stationary coordinate system,
A three-phase alternating current obtained by performing a two-phase / three-phase conversion on the fundamental wave anti-phase portion of the two-phase alternating current obtained from the second rotational coordinate conversion unit or the fundamental wave anti-phase portion of the two-phase alternating current. 5. The power receiving and distributing equipment according to claim 3, wherein the fundamental wave negative phase component is used as a detection output of the fundamental wave negative phase detection unit.

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