JP4146606B2

JP4146606B2 - Power distribution protection system

Info

Publication number: JP4146606B2
Application number: JP2000184482A
Authority: JP
Inventors: 知恵高橋; 行盛岸田; 博之笹尾; 貢高橋
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2000-06-20
Filing date: 2000-06-20
Publication date: 2008-09-10
Anticipated expiration: 2020-06-20
Also published as: JP2002010481A

Description

【０００１】
【発明の属する技術分野】
本発明は、商用電源と自家発電機を併用する受配電系統において、短絡事故の発生時に、他の系統への影響を低減する受配電保護システムに関する。
【０００２】
【従来の技術】
従来より、商用電源と自家発電機を併用する受配電系統が知られている。当該受配電系統において、例えば、商用電源側の系統（以下、商用系統という）の商用母線から下流側で短絡事故が発生すると商用電源の電圧が急激に低下すると共に、商用母線と自家発電機側の系統（以下、自家発系統という）の自家発母線との連携点を介して自家発電機から商用系統に過電流が流れ込む。この場合、自家発電機を保護するには当該自家発電機を停止させなければならない。しかし、一般に自家発母線の下流には、商用電源からの給電が停止したときも継続して運転しなければならない重要負荷を接続していることが多く、自家発電機を停止させるのは好ましくない。
【０００３】
上記短絡事故の発生時の自家発電機の停止を避けるために、特開平6-339227号公報には、商用系統と自家発系統との連携点に高速スイッチと事故検出器を設置しておき、当該事故検出器により商用系統での短絡事故が検出された場合には、高速スイッチを動作させて商用系統と自家発系統を高速に切り離すシステムが開示されている。
【０００４】
また、最近の計算機を組み込んだ機器の増加に伴い、瞬時に電圧が低下すること（以下、瞬低という）により運転停止に陥る負荷が多くなった。このため、商用系統での短絡事故により生じる瞬低の影響を、自家発母線に接続されている重要な負荷が受けないように配慮した受配電システムが要求されている。
【０００５】
上記瞬低が起こるのは、短絡箇所に過電流が流れ込むためである。短絡事故発生時における瞬低を防止するため、例えば、特開平6-233459号公報には、過電流が流れた場合に回路に直列に高インピーダンスを挿入して電流を小さくする限流器を備える装置が開示されている。当該限流器を採用することで、短絡事故発生時における系統内の電圧の変動を緩和することができる。
【０００６】
また、特開平6-255370号公報には、上記限流器を使うことにより事故電流を小さくして、事故電流を遮断する遮断器の責務（要求される性能）を軽減する装置が開示されている。当該装置を採用することで、より遮断容量の小さな遮断器が使用可能となり、また、遮断器自体の寿命を改善することもできる。
【０００７】
一般に商用系統のみから成る受配電系統に自家発系統を追加する場合、短絡事故の発生時に流れる過電流の増加に対処するために既設の遮断器を大容量のものに取り換える必要が生じるが、上記限流器を採用することで、短絡事故発生時に流れる過電流を限流することができ、既設の遮断器をそのまま利用することができるようになる。
【０００８】
図７は、上記の従来技術を用いて構成される受配電システム５００（点線で区切る下側の範囲）を示す。商用系統３は、上流側より順に、遮断器５、限流動作指令信号の入力に応じて限流動作を行う限流器６、当該限流器６の直ぐ下流に流れる電流を測定し、測定値が予定値を超えた場合に限流器６に対して限流動作指令信号を出力する過電流検出器７、商用母線８が接続されている。商用母線８の各支流には、分岐遮断器９，…，９’を介して一般負荷１１，…，１１’が接続されている。
【０００９】
自家用系統１３は、上流側より順に、遮断器１４、限流動作指令信号の入力に応じて限流動作を行う限流器１５、当該限流器１５の直ぐ下流に流れる電流を測定し、測定値が予定値を超えた場合に限流器１５に対して限流動作指令信号を出力する過電流検出器１６、自家発母線１７が接続されている。自家発母線１７の各支流には、分岐遮断器１８，…，１８’を介して重要負荷２０，…，２０’が接続されている。
【００１０】
商用母線８と自家発母線１７は、連携点遮断器２１、連携点限流器２２、及び、当該連携点限流器２２に流れる電流が予定値を超えた場合に上記限流器２２に限流動作指令信号を出力する過電流検出器２３を介して接続されている。
【００１１】
過電流が流れた場合、分岐遮断器９，…，９’、１８，…，１８’は、遮断器５，１４よりも早く動作するように設定される。また、連携点遮断器２１の動作時間は遮断器５，１４と同じ値に設定される。
【００１２】
過電流検出器７，１６，２３及び限流器６，１５，２２は、短絡事故発生時に生じる過電流の最初のピークを制限して遮断器にかかる負担を軽減するために設けられる。即ち、過電流の発生後、各遮断器が作動する前に、過電流検出器７，１６，２３が限流動作指令信号を出力し、限流器６，１５，２２が限流動作を完了するように設定されている。限流器用の過電流検出器７，１６，２３は、過電流が収まったときに限流器に限流動作の解除指令信号を出力する。
【００１３】
上記構成の受配電システムにおける動作について簡単に説明を行う。
通常は、一般負荷１１，…，１１’は主に商用電源１から電力の供給を受けると共に、重要負荷２０，…，２０’は主に自家発電機１２から電力の供給を受けている。商用母線８から下流側で短絡事故が起きると、商用電源１からは限流器６を通って過電流が流れる。過電流検出器７は、当該過電流を検出して限流器６を作動させる。同時に自家発母線１７からも連携点の限流器２２を通って過電流が流れるため、過電流検出器２３が過電流を検出して限流器２２を作動させる。自家発母線１７に流れる過電流は、限流器２２により最初のピークを迎える前に限流される。これにより、自家発母線１７における急激な電圧降下が抑制され、重要負荷２０の運転停止が避けられる。また、限流器２２の働きにより、遮断器１４が作動して自家発電機１２からの給電が停止するのを防止することができる。
【００１４】
例えば、分岐系統１０において短絡事故が発生した場合、分岐遮断器９が限流器６，２２の動作により限流された過電流によって作動して電路を遮断する。このように、分岐遮断器９には、限流器６，２２の働きにより過電流が印加されることが無いため、比較的遮断容量の小さなものを採用することができる、これにより配電設備のコスト低減を図ることができる。
【００１５】
分岐遮断器９が作動して、限流器６，２２により限流された過電流の一般負荷１１への給電が遮断されると、限流器６，２２に流れる電流は通常の負荷電流に復帰する。これに対応して過電流検出器７，２３は、限流器６，２２に限流解除指令信号を出力し、限流器６，２２の限流動作を解除する。これにより短絡事故発生時の一連の処理が完了する。
【００１６】
商用母線８と自家発母線１７は、切り離されていないため、再連携のための周波数や位相などの調整の必要が無く、短絡事故発生時の処理完了後、直ちに通常の状態に戻ることができる。
【００１７】
一方、自家発系統１３側で短絡事故が発生した場合には、主に限流器による遮断器の遮断責務の軽減、遮断容量の低下すなわち低コスト化を目的として以下の処理が実行される。
【００１８】
自家発母線１７から下流側で短絡事故が起きた場合、自家発側限流器１５と連携点限流器２２が動作して、過電流を小さく限流する。例えば、分岐系統１９で短絡事故が発生した場合、分岐遮断器１８が上記限流された過電流により作動する。過電流の遮断に伴い限流器１５，２２の限流動作が解除されて通常状態に戻る。当該短絡事故の場合、限流器１５，２２により分岐遮断器１８の遮断責務が軽減され、限流器を用いない場合に比べて容量の小さな遮断器の使用が可能になる。また、自家発電機１２の過電流も限流器１５により阻止できるので、自家発電機１２の停止も免れる。また、自家発母線１７自体で短絡事故が起きた場合も、遮断器１４、連携点遮断器２１はそれぞれ限流器１５、２２によって限流された電流を遮断するだけでよくなり、大きな遮断容量の遮断器が必要無くなり低コスト化を図ることができる。どちらの事故の場合でも、商用母線８の急激な電圧低下は、防止される。
【００１９】
【発明が解決しようとする課題】
図７で示した従来技術で構成される受配電保護システムは、限流器を用いることにより短絡事故により発生する過電流を抑制し、直列遮断器に必要とされる遮断責務を軽減でき、さらに商用側事故の影響による瞬時電圧低下や停電を自家発電機側に発生させないようにできるといった利点を有する。
【００２０】
しかし、上記利点を得るためには、商用電源１側の短絡事故発生時に、自家発母線１７から商用母線８に流れ込む過電流によって連携点限流器２２が限流動作するまでは自家発側限流器１５が動作しないことが絶対的に要求される。万一、連携点限流器２２が限流動作する前に限流器１５が動作すると自家発系統１３に高インピーダンスが挿入されることになり、自家発母線１７の電圧が低下して重要負荷２０，…，２０’の継続動作を確保できないことになる。
【００２１】
仮に、限流器６，１５の動作開始タイミングを遅延させ、限流器２２を最も早く動作するように設定すると、上記問題は解決できる。しかし、例えば、重要負荷側２０で短絡事故が発生した場合、上記遅延させた時間だけ、重要負荷２０の短絡箇所に限流されていない過電流が流れ込み、瞬間的に他の重要負荷に供給される電圧が低下する。当該他の重要負荷に供給する電圧の低下を防ぐには、遮断器１８を作動させれば良いのであるが、この場合、限流器１８には、限流されていない過電流に対して正常に遮断動作し得るだけの大きな遮断容量を備えることが必要になる。これでは、遮断器の遮断債務の軽減を目的として限流器を採用した意味が没却されてしまう。
【００２２】
そこで、本発明は、商用電源と自家発電機とを併用する系において、上記各限流器の動作タイミングの制御の難しさを解消し、短絡事故の発生時に他方の系への影響を効果的に低減することのできる受配電保護システムを提供することを目的とする。
【００２３】
【課題を解決するための手段】
請求項１に記載の受配電保護システムでは、商用電源に、第１遮断器（５）と、第１限流器（６）と、１以上の負荷であってそれぞれの上流側に第１分岐遮断器（９）を有している第１負荷（１１）と、を順に接続してある商用母線と、自家発電機に、第２遮断器（１４）と、第２限流器（１５）と、１以上の負荷であってそれぞれの上流側に第２分岐遮断器（１８）を有している第２負荷（２０）と、を順に接続してある自家発母線と、を含んでおり、上記商用母線の第１限流器と第１分岐遮断器との間の部分と、上記自家発母線の第２限流器と第２分岐遮断器との間の部分とが、第３遮断器（２１）と、第３限流器（２２）と、を介して接続されている受配電系統で用いる受配電保護システムであって、短絡事故検出部と、制御部と、を含んでおり、上記短絡事故検出部が、上記商用母線と自家発母線とを第３遮断器と第３限流器とを介して接続する線での過電流の発生と、該過電流の流れる方向と、を検出する第１短絡方向検出器（２６）を含んでおり、上記制御部が、第１短絡方向検出器によって商用母線から自家発母線へと過電流が流れていることが検出された場合（ステップＳ２、Ｓ２２、Ｓ３２）、上記第１、第２、第３遮断器が動作する前に第２、第３限流器を動作させる（２３、ステップＳ７、Ｓ２７、Ｓ３７）ものであり、第１短絡方向検出器によって自家発母線から商用母線へと過電流が流れていることが検出された場合、上記第１、第２、第３遮断器が動作する前に第１、第３限流器を動作させる（２３、ステップＳ４、Ｓ２４、Ｓ３４）ものであり、上記第１、第２分岐遮断器が、限流器によって限流された過電流によって、第１、第２、第３遮断器よりも早く動作するものである、ことを特徴とする。
【００２４】
請求項２に記載の受配電保護システムでは、請求項１に記載の受配電保護システムであって、上記短絡事故検出部が含んでいる１以上の短絡方向検出器の各々が、過電流を検出していない場合、事故処理完了信号を出力するものであり、上記制御部が、全ての短絡方向検出器からの事故処理完了信号の入力に応じて（ステップＳ５、Ｓ８、Ｓ２５、Ｓ２８、Ｓ３５、Ｓ３８）、第１、第２、第３限流器の動作を解除するものである（ステップＳ６、Ｓ９、Ｓ２６、Ｓ２９、Ｓ３６、Ｓ３９ ) 、ことを特徴とする。
【００２５】
請求項３に記載の受配電保護システムでは、請求項１又は請求項２に記載の受配電保護システムであって、上記短絡事故検出部が、更に、第２、第３短絡方向検出器（２４、２５）を含んでおり、上記第２短絡方向検出器（２４）が、商用母線での過電流の発生と、該過電流の流れる方向と、を検出するものであり、上記第３短絡方向検出器（２５）が、自家発母線での過電流の発生と、該過電流の流れる方向と、を検出するものであり、上記制御部が、制御装置（２７）を含んでおり、上記制御装置が、第２、第３短絡方向検出器によって商用母線と自家発母線との下流側へと過電流が流れていることが検出され、且つ、第１短絡方向検出器によって商用母線から自家発母線へと過電流が流れていることが検出された場合（ステップＳ２）、第２、第３限流器を動作させる（ステップＳ７）ものであり、第２、第３短絡方向検出器によって商用母線と自家発母線との下流側へと過電流が流れていることが検出され、且つ、第１短絡方向検出器によって自家発母線から商用母線へと過電流が流れていることが検出された場合、第１、第３限流器を動作させる（ステップＳ４）ものである、ことを特徴とする。
【００２６】
請求項４に記載の受配電保護システムでは、請求項１又は請求項２に記載の受配電保護システムであって、上記短絡事故検出部が、更に、第２、第３短絡方向検出器（２４、２５）を含んでおり、上記第２短絡方向検出器（２４）が、商用母線での過電流の発生と、該過電流の流れる方向と、を検出するものであり、上記第３短絡方向検出器（２５）が、自家発母線での過電流の発生と、該過電流の流れる方向と、を検出するものであり、上記制御部が、制御装置（２７’）と、過電流検出器（２３）と、を含んでおり、上記制御装置が、第２、第３短絡方向検出器によって商用母線と自家発母線との下流側へと過電流が流れていることが検出され、且つ、第１短絡方向検出器によって商用母線から自家発母線へと過電流が流れていることが検出された場合（ステップＳ２２）、第２限流器を動作させる（ステップＳ２７）ものであり、第２、第３短絡方向検出器によって商用母線と自家発母線との下流側へと過電流が流れていることが検出され、且つ、第１短絡方向検出器によって自家発母線から商用母線へと過電流が流れていることが検出された場合、第１限流器を動作させる（ステップＳ４、Ｓ２４）ものであり、上記過電流検出器が、商用母線と自家発母線との間に流れる過電流を検出し、過電流の検出に応じて第３限流器を動作させる限流動作信号を出力するものである、ことを特徴とする。
【００２７】
請求項５に記載の受配電保護システムでは、請求項１又は請求項２に記載の受配電保護システムであって、上記制御部が、制御装置（２７”）と、過電流検出器（２３）と、を含んでおり、上記制御装置が、第１短絡方向検出器によって商用母線から自家発母線へと過電流が流れていることが検出された場合（ステップＳ３２ ) 、第２限流器を動作させる（ステップＳ３７ ) ものであり、第１短絡方向検出器によって自家発母線から商用母線へと過電流が流れていることが検出された場合、第１限流器を動作させる（ステップＳ３４ ) ものであり、上記過電流検出器が、商用母線と自家発母線との間に流れる過電流を検出し、過電流の検出に応じて第３限流器を動作させる限流動作信号を出力するものである、ことを特徴とする。
【００３２】
【発明の実施の形態】
（１）発明の概要
本発明の受配電保護システムは、商用電源と自家発電機を併用する受配電系統において、限流動作指令信号の入力に応じて限流動作を行う第１限流器を介して上記商用電源に接続されている商用母線と、第２限流器を介して上記自家発電機に接続されると共に、上記商用母線と第３限流器を介して接続されている自家発母線と、上記商用母線及び自家発母線から下流側での短絡事故の発生を検出し、短絡事故の発生、及び、当該短絡事故が商用母線及び自家発母線の何れで発生したのかを表す事故情報信号を出力する短絡事故検出部と、上記短絡事故検出部から出力される事故情報信号に基づいて商用母線及び自家発母線の何れで短絡事故が発生したのかを判断し、当該判断より特定された母線側の限流器及び第３限流器の内、少なくとも第３限流器を含む１又は２の限流器に対して限流動作指令信号を送る制御装置とを備えることを特徴とする。上記制御装置を利用して、短絡事故発生時における限流器の動作タイミングの調整を行うことで、短絡事故の発生時に他の系における急激な電位の低下を効果的に防止する。また、適切な限流動作を実現することで、短絡事故発生時に各遮断器に要求される遮断責務を軽減することができる。
【００３３】
また、上記第１限流器、第２限流器、及び、第３限流器の各近傍に第１遮断器、第２遮断器、及び、第３遮断器を備え、上記短絡事故検出部が短絡事故を検出してから所定の限流器が限流動作を完了するまでに要する時間が、当該短絡事故の発生から上記何れの遮断器が作動するのに要する時間よりも短くなるように設定したことを特徴とする。当該構成を採用することで、短絡事故を起こした系の事故処理が完了する前に、他の系の遮断器の誤作動を防止することができる。
以下、上記特徴を具備する受配電保護システムの実施の形態１乃至３について添付の図面を用いて順に説明する。
【００３４】
（２）実施の形態１
(2-1)システム構成
図１は、実施の形態１に係る受配電保護システム１００の構成を示す。図７を用いて説明した従来の受配電保護システム５００と同じ構成物には同じ参照番号を付す。当該システム１００は、商用電源１からそれぞれの需要家へと伸びる商用系統２の内、受電端４を介して接続されている一の需要家内の商用系統３、及び、需要家内が備える自家発電機１２より伸びる自家発系統１３の配線で構成される（点線で区切る下側の範囲）。
【００３５】
商用系統３は、上流側より順に、遮断器５、限流動作指令信号の入力に応じて限流動作を行う限流器６、限流器６に流れる電流及び電圧を測定し、測定した電流値から過電流の発生を検出すると共に、電流と電圧の位相差から過電流の流れる方向を特定し、過電流の発生及び当該過電流の流れる向きを表す事故情報信号を制御装置２７に出力する短絡方向検出器２４、並びに、商用母線８が接続されている。商用母線８には、分岐遮断器９，…，９’が接続されており、該分岐遮断器９，…，９’の下流より伸びる線（分岐系統１０，…，１０’）の終端には、一般負荷１１，…，１１’が接続されている。
【００３６】
自家用系統１３は、上流側より順に、遮断器１４、限流動作指令信号の入力に応じて限流動作を行う限流器１５、限流器１５に流れる電流及び電圧を測定し、電流の測定値から過電流の発生を検出すると共に、電流と電圧の位相差から過電流の流れる方向を特定し、過電流の発生及び当該過電流の流れる向きを表す事故情報信号を制御装置２７に出力する短絡方向検出器２５、並びに、自家発母線１７が接続されている。自家発母線１７には、分岐遮断器１８，…，１８’が接続されており、分岐遮断器１８，…，１８’の下流より伸びる線（分岐系統１９，…，１９’）の終端には、重要負荷（需要家が無停電動作させようとして接続している負荷）２０，…，２０’が接続されている。
【００３７】
商用母線８と自家発母線１７は、連携点遮断器２１、連携点限流器２２、及び、限流器２２に流れる電流を測定し、当該測定値から過電流の発生を検出し、過電流の発生及び当該過電流の流れる向きを表す事故情報信号を制御装置２７に出力する短絡方向検出器２６を介して互いに接続されている。
【００３８】
遮断器５，１４は、過電流検出手段を備えており、所定値を超える電流が所定時間Ｔだけ流れた場合に通電を遮断する。また、遮断器９，…，９’、１８，…，１８’も過電流検出手段を備えており、所定値を超える電流が所定時間Ｔ’だけ流れた場合に通電を遮断する。遮断器５，１４と分岐遮断器９，…，９’、１８，…，１８’の動作特性は、通常の配電保護形式である時限協調方式となるように設定する。即ち、過電流が流れた場合に分岐遮断器９，…，９’、１８，…，１８’は、遮断器５，１４よりも早く動作する（Ｔ’＜Ｔの関係を満たす）ものを採用する。但し、通常の遮断器の遮断動作完了までに要する時間は、交流電流が３サイクルする期間であり、分岐遮断器９，…，９’、１８，…，１８’もこれ以上早く事故電流を遮断することはできない。なお、連携点遮断器２１は、遮断器５，１４と同じ動作時間Ｔのものを採用する。
【００３９】
短絡方向検出器２４，２５，２６は、系に流れる電流及び電圧を測定する測定器と、該測定器による電流の測定値が所定のしきい値を超えた場合に過電流が発生したと判断すると共に、測定される電流と電圧の位相差より過電流の流れる方向を特定し、当該過電流の発生及びその流れる方向を表すディジタルの事故情報信号を出力するＤＳＰ（Digital Signal Processor）で構成される。短絡方向検出器２４，２５，２６は、過電流が発生してから時間ｔ１経過後に事故情報信号を出力する。
また、短絡方向検出器２５，２６，２７は、系を流れる電流が過電流から通常の負荷電流に復帰した場合に、制御装置２７に対して事故処理完了信号を出力する。
【００４０】
制御装置２７は、演算処理装置（以下、ＣＰＵという）２７ａ、信号処理プログラムを格納しているＲＯＭ２７ｂ、及び、前記ＣＰＵ２７ａによる信号処理プログラムの実行時に作業領域として利用されるＲＡＭ２７ｃで構成される。ＣＰＵ２７ａは、短絡方向検出器２４，２５，２６からの事故情報信号に基づいて短絡事故の内容を判別し、又は、事故処理完了信号に基づいて事故処理の完了を認識し、前記事故情報信号を受けてから時間ｔ２後に所定の限流器６，１５，２２に対して限流動作指令信号又は限流動作解除指令信号を出力する。なお、当該信号処理プログラムの内容については、後に説明する。
【００４１】
限流器６，１５，２２は、短絡事故発生時に生じる過電流の最初のピークを制限して遮断器にかかる負担を軽減するために設けられる。限流器６，１５，２２は、制御装置２７から限流動作指令信号を受けてから時間ｔ３経過後に限流動作を完了する。
また、限流器６，１５，２２は、限流動作解除指令信号の入力に応じて限流動作を解除する。
【００４２】
限流器により限流された過電流に対して動作する遮断器がダメージを受ける前に、必要な限流器による限流動作を確実に完了させるため、各遮断器に過電流が流れ出してから作動するまでに要する時間Ｔ，Ｔ’よりも、上記時間ｔ１，ｔ２，ｔ３の合計が大幅に小さくなるように、短絡方向検出器２４，２５，２６、制御装置２７、限流器６，１５，２２、及び、遮断器５，９，…，９’，１４，１８，…，１８’，２１を選択する。
【００４３】
(2-2)短絡事故処理
図２は、短絡事故の発生時に制御装置２７が実行する信号処理のフローチャートである。以下、図１に示す受配電保護システムの構成、及び、図２に示す制御装置２７の信号処理のフローを参照しつつ、上記構成の受配電保護システム１００で短絡事故が発生した際に実行する事故処理について、短絡事故発生箇所毎に説明する。
【００４４】
(2-2-1)商用電源側の分岐系統での短絡事故
商用電源１側の分岐系統１０、…、１０’の何れか１つ、例えば、分岐系統１０において短絡事故が発生した場合について説明する。当該短絡事故の発生に伴い商用電源１からは、限流動作を行っていない限流器６を通って過電流が流れる。この際、短絡方向検出器２４は、限流器６の下流側の短絡事故であることを検出し、当該内容を示す事故情報信号を制御装置２７に出力する。また、当該短絡事故の発生に伴い自家発電機１２からは、自家発電側限流器１５、自家発母線１７、連携点限流器２２を通り過電流が分岐系統１０の短絡事故箇所に流れ込む。自家発電機１２側の短絡方向検出器２５は、限流器１５の下流側の短絡事故であることを検出し、これを表す事故情報信号を制御装置２７に出力する。また、連携点短絡方向検出器２６は、限流器２２の図面左側の商用電源１側での短絡事故であることを検出し、これを表す事故情報信号を制御装置２７に出力する。
【００４５】
制御装置２７は、短絡方向検出器２４，２５，２６から事故情報信号が入力された場合に短絡事故が発生したと判断し（図２のステップＳ１でＹＥＳ）、短絡方向検出器２４，２５，２６からの事故情報信号の内容に基づいて事故内容の判別を行う（図２のステップＳ２）。具体的には、制御装置２７は短絡方向検出器２４，２５からの事故情報信号が共に下流側での短絡事故を表し、短絡方向検出器２６からの事故情報信号が商用電源１側での短絡事故を表していることに基づいて、商用電源１側の系統での短絡事故であると判断し（図２のステップＳ３でＹＥＳ）、商用側限流器６、及び、連携点限流器２２に限流動作指令信号を出力する（図２のステップＳ４）。限流器６及び２２は、当該限流動作指令信号の入力に応じて、短絡事故により発生した過電流がピーク値を迎える前に電流の絞込みを完了する。以下、限流器６及び２２により絞り込まれた過電流を事故電流という。
【００４６】
なお、システムの簡略化及び処理の迅速化を目的として、短絡方向検出器２４，２５を省き、短絡方向検出器２６のみを設け、当該短絡方向検出器２６からの事故情報信号が表す短絡事故の発生した方向だけに基づいて上記ステップＳ３の処理を実行することとしても良い。
【００４７】
短絡事故が商用電源１側の分岐系統１０で発生した場合、事故電流に応じて、遮断器５よりも早く作動するように設定されている分岐遮断器９が作動して、事故電流が短絡箇所に流れ込むのを遮断する。当該遮断器９の働きにより系内に流れる電流が通常の負荷電流に復帰する。短絡方向検出器２４，２６は、商用電源１からの供給される電流が通常の負荷電流に復帰すると事故処理完了信号を制御装置２７に出力する。制御装置２７は、事故処理完了信号の入力に応じて（図２のステップＳ５でＹＥＳ）、限流器６，２２に対して限流解除指令信号を出力する（ステップＳ６）。以上の処理により制御装置２７による一連の事故処理が完了する。
【００４８】
連携点限流器２２の働きにより、自家発母線１７から商用母線８へと流れ込む電流は小さく抑制される。この際、自家発側限流器１５は限流動作しておらず、自家発母線１７における電位が急激に低下することはない。これにより、重要負荷２０，…，２０’の継続的な動作が保証される。
また、自家発電機１２から流れる過電流も連携点限流器２２で通常の負荷電流に抑制されるため、遮断器１４は動作せず自家発電機１２の停止も避けられる。
【００４９】
(2-2-2)商用電源側の商用母線での短絡事故
次に、商用電源１側の商用母線８で短絡事故が発生した場合について考察する。この場合、短絡方向検出器２４，２５，２６は、上記分岐系統１０での短絡事故発生時と同じ事故情報信号を出力する。制御装置２７は、当該事故情報信号の入力に応じて短絡事故の発生を検出し（図２のステップＳ１でＹＥＳ）、入力される事故情報信号の内容に基づいて事故内容の判別を行う（図２のステップＳ２）。具体的には、制御装置２７は短絡方向検出器２４，２５からの事故情報信号が共に下流側での短絡事故を表し、短絡方向検出器２６からの事故情報信号が商用電源１側での短絡事故を表していることに基づいて、商用電源１側の系統での短絡事故であると判断し（図２のステップＳ３でＹＥＳ）、商用側限流器６、及び、連携点限流器２２に限流動作指令信号を出力して商用母線８に流れ込む過電流を小さく絞り込む（図２のステップＳ４）。当該小さく絞り込まれた過電流により、商用側遮断器５及び連携点限流器２１が作動する。これにより自家発電機１２より供給される電流が通常の負荷電流に復帰する。これに伴い短絡方向検出器２４，２６は、事故処理完了信号を制御装置２７に出力する。制御装置２７は、前記事故処理完了信号の入力に対して（図２のステップＳ５でＹＥＳ）、限流器６，２２に対して限流解除指令信号を出力する（図２のステップＳ６）。以上の処理により、事故処理が完了する。
【００５０】
連携点限流器２２の働きにより、自家発母線１７から商用母線８へと流れ込む電流は小さく抑制される。この際、自家発側限流器１５は限流動作しておらず、自家発母線１７における電位が急激に低下することはない。これにより、重要負荷２０，…，２０’の継続的な動作が保証される。また、自家発電機１２から流れる過電流も連携点限流器２２で通常の負荷電流に抑制されるため、遮断器１４は動作せず自家発電機１２の停止も避けられる。
【００５１】
(2-2-3)自家発電機側での短絡事故
引き続き、自家発電機１２側で短絡事故が発生した場合について説明する。自家発系統１３側で短絡事故が発生した場合には、重要負荷２０，…，２０’への電圧低下の影響や停電を防ぐのではなく、限流器による遮断器の遮断責務の軽減、遮断容量の低下すなわち低コスト化を目的として以下の処理を実行する。
【００５２】
自家発電機１２側で短絡事故が起った場合、自家発電機１２からは、限流器１５を通って過電流が流れる。このため、短絡方向検出器２５は、限流器１５の下流側の短絡事故であることを表す事故情報信号を制御装置２７に出力する。同時に商用電源１からは商用側限流器６、商用母線８、連携点限流器２２を通り過電流が自家発母線１７に流れ込む。商用側限流器６の短絡方向検出器２４は、限流器６の下流側の短絡事故であることを表す事故情報信号を制御装置２７に出力する。連携点限流器２２の短絡方向検出器２６は、限流器２２の図面右側の自家発側での短絡事故であることを表す事故情報信号を制御装置２７に出力する。
【００５３】
制御装置２７は、短絡方向検出器２４，２５及び２６からの事故情報信号の入力により短絡事故が発生したと判断し（図２のステップＳ１でＹＥＳ）、短絡方向検出器２４，２５及び２６からの事故情報信号の内容に基づいて事故内容の判別を行う（図２のステップＳ２）。具体的には、制御装置２７は、短絡方向検出器２４，２５からの事故情報信号が共に下流側での短絡事故を表し、短絡方向検出器２６からの事故情報信号が自家発電機１２側での短絡事故を表していることから、自家発電機１２側の系統での短絡事故であると判断し（図２のステップＳ３でＮＯ）、自家発電機１２側の限流器１５、及び、連携点限流器２２に限流動作指令信号を出力する（図２のステップＳ７）。当該限流動作指令信号の入力に応じて限流器１５及び２２は、短絡事故により発生した過電流がピーク値を迎える前に電流の絞込みを行う。
【００５４】
限流器１５、２２の限流動作により商用母線８から自家発母線１７へ流れる電流は小さく抑制される。この際、商用側限流器６は動作していないので商用母線８へ供給する電圧の低下を防ぐことができる。例えば、自家発電機１２側の短絡箇所が分岐系統１９に在る場合、短絡箇所の直ぐ上流に位置する分岐遮断器１８は、限流器１５、２２の動作により小さく絞られた事故電流を遮断する。事故電流が遮断されると限流器１５、２２の電流は負荷電流に復帰するため短絡方向検出器２５、２６は、事故処理完了信号を制御装置２７に出力する。制御装置２７は、事故処理完了信号の入力に応じて（図２のステップＳ８でＹＥＳ）、限流器１５、２２に限流解除指令信号を出力して（図２のステップＳ９）、限流動作を解除する。
【００５５】
事故箇所が自家発母線１７に在る場合、限流器１５、２２によって限流された電流によって遮断器１４、連携点遮断器２１は動作する。この場合であっても、商用電源１側における一般負荷１１，…，１１’への電力供給は継続される。遮断器１４及び２１の動作により限流器１５、２２の電流は、負荷電流に復帰するため短絡方向検出器２５、２６は、事故処理完了信号を制御装置２７に出力する。制御装置２７は、事故処理完了信号の入力に応じて（図２のステップＳ８でＹＥＳ）、限流器１５、２２に限流解除指令信号を出力して（図２のステップＳ９）、限流動作を解除する。
【００５６】
（３）実施の形態２
図３は、実施の形態２に係る受配電保護システム２００の構成を示す図である。図１に示した受配電保護システム１００と同じ構成物には同じ参照番号を付してここでの重複した説明は省く。図１に示した実施の形態１にかかる受配電保護システム１００と異なる点は、方向短絡限流器２６の他に、従来の受配電保護システム５００で使用していた過電流検出器２３を併用することである。即ち、受配電保護システム２００では、商用電源１側、自家発電機１２側の何れかで短絡事故が発生した場合、制御装置２７’からの限流動作信号によらず、過電流検出器２３が限流器２２の動作を直接制御する。この結果、商用母線８と自家発母線１７との連携点を流れる電流が素早く絞り込まれ、短絡していない側の系統に流れる電位の低下をより迅速に防ぐことができる。過電流検出器２３は、所定の遮断器が作動して過電流が通常の負荷電流に復帰した場合、限流解除指令信号を出力して限流器２２の限流動作を解除する。
【００５７】
図４は、受配電保護システム２００の備える制御装置２７’の実行する信号処理のフローチャートである。各ステップ番号の下一桁の番号は、図２に示した受配電保護システム１００の備える制御装置２７の実行する事故処理のフローチャートの対応するステップ番号に対応する。制御装置２７’では、ステップＳ２４において、商用電源１側の限流器６に対してのみ限流動作指令信号を出力する点、及び、ステップＳ２７において、自家発電機１２側の限流器１５に対してのみ限流動作指令信号を出力する点で、受配電保護システム１００で制御装置２７が実行する事故処理と相異する。当該構成を採用することで、制御装置の実行する処理内容の簡略化が行われ、処理の迅速を図ることができる。
【００５８】
（４）実施の形態３
図５は、実施の形態３に係る受配電保護システム３００の構成を示す図である。図３に示した受配電保護システム２００と同じ構成物には同じ参照番号を付してここでの重複した説明は省く。図３に示した受配電保護システム２００と異なる点は、短絡方向検出器２４及び２５を除去したことである。制御装置２７”は、短絡方向検出器２６からの事故情報信号の表す過電流の流れる方向の情報に基づいて短絡事故を起こした系統を特定する。具体的には、過電流が商用電源１側へと流れる場合には、短絡事故が商用電源１側で発生したと判断して限流器６に限流動作信号を出力する。一方、過電流が自家発電機１２側へと流れる場合には、自家発電機１２側で短絡事故が発生したと判断して限流器１５に限流動作信号を出力する。
【００５９】
図６は、受配電保護システム３００の備える制御装置２７”の実行する事故処理のフローチャートである。各ステップ番号の下一桁は、図４に示した受配電保護システム２００の備える制御装置２７’の実行する事故処理のフローチャートの対応するステップ番号の下一桁に対応する。制御装置２７”では、ステップＳ２２における事故内容の判別処理において、短絡方向検出器２６からの事故情報信号の表す過電流の流れる方向の情報に基づいて短絡事故を起こした系統を特定する。この他、ステップＳ３４において、商用電源１側の限流器６に対してのみ限流動作指令信号を出力する点、及び、ステップＳ３７において、自家発電機１２側の限流器１５に対してのみ限流動作指令信号を出力する点は、受配電保護システム２００と同じである。当該構成を採用することで、制御装置２７”の実行する処理内容の一層の簡略化を図り処理の高速化を図ると共に、システムの構成を簡略化することでコストダウンを図ることができる。
【００６０】
【発明の効果】
請求項１乃至請求項５に記載の受配電保護システムでは、短絡事故発生時における限流器の動作タイミングの調整を行うことで、短絡事故の発生時に他の系における急激な電位の低下を効果的に防止する。また、適切な限流動作を実現することで、短絡事故発生時に各遮断器に要求される遮断責務を軽減することができる。また、短絡事故検出部が短絡事故を検出してから所定の限流器が限流動作を完了するまでに要する時間が、当該短絡事故の発生から上記何れの遮断器が作動するのに要する時間よりも短くなるように設定したことによって、短絡事故を起こした系の事故処理が完了する前に、他の系の遮断器の誤作動を防止することができる。
【図面の簡単な説明】
【図１】実施の形態１に係る受配電保護システムの構成を示す図である。
【図２】制御装置の実行する信号処理フローチャートである。
【図３】実施の形態２に係る受配電保護システムの構成を示す図である。
【図４】制御装置の実行する信号処理のフローチャートである。
【図５】実施の形態３に係る受配電保護システムの構成を示す図である。
【図６】制御装置の実行する信号処理のフローチャートである。
【図７】従来の受配電保護システムの構成を示す図である。
【符号の説明】
１商用電源、２商用系統、３需要家内の商用系統、４受電端、５，１４，２１遮断器、６，１５，２２限流器、８商用母線、９…９’，１８…１８’ 分岐遮断器、１０…１０’，１９…１９’ 分岐系統、１１…１１’ 一般負荷、２０…２０’ 重要負荷、２７，２７’，２７”制御装置。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power distribution protection system that reduces the influence on other systems when a short circuit accident occurs in a power distribution system that uses both a commercial power source and a private generator.
[0002]
[Prior art]
Conventionally, a power distribution system using both a commercial power source and a private generator is known. In the power distribution system, for example, when a short-circuit accident occurs downstream from the commercial bus of the commercial power supply system (hereinafter referred to as the commercial system), the voltage of the commercial power supply suddenly decreases, and the commercial bus and the private generator side Overcurrent flows into the commercial system from the private generator through a linkage point with the self-generated bus of this system (hereinafter referred to as the self-generated system). In this case, in order to protect the private generator, the private generator must be stopped. However, in general, downstream of the private bus is often connected with an important load that must be continuously operated even when power supply from the commercial power supply is stopped, and it is not preferable to stop the private generator. .
[0003]
In order to avoid stopping the private generator when the short-circuit accident occurs, JP-A-6-339227 discloses that a high-speed switch and an accident detector are installed at the connection point between the commercial system and the private system, A system is disclosed in which when the accident detector detects a short-circuit accident in a commercial system, a high-speed switch is operated to disconnect the commercial system and the in-house system at high speed.
[0004]
In addition, with the recent increase in the number of devices incorporating computers, the load that causes the operation to stop due to the instantaneous voltage drop (hereinafter referred to as “instantaneous drop”) has increased. For this reason, there is a demand for a power distribution system that takes into account the influence of a sag caused by a short circuit accident in a commercial system so that an important load connected to the private bus is not received.
[0005]
The momentary drop occurs because an overcurrent flows into the short-circuit portion. In order to prevent a sag in the event of a short circuit accident, for example, Japanese Patent Laid-Open No. 6-233459 includes a current limiter that reduces the current by inserting a high impedance in series with the circuit when an overcurrent flows. An apparatus is disclosed. By adopting the current limiting device, it is possible to reduce fluctuations in the voltage in the system when a short-circuit accident occurs.
[0006]
Japanese Patent Application Laid-Open No. 6-255370 discloses a device that reduces the fault current by using the current limiting device and reduces the duty (required performance) of the circuit breaker that interrupts the fault current. Yes. By adopting the device, a circuit breaker having a smaller breaking capacity can be used, and the life of the circuit breaker itself can be improved.
[0007]
In general, when adding an in-house system to a power distribution system consisting only of a commercial system, it is necessary to replace the existing circuit breaker with a large-capacity one to cope with the increase in overcurrent that occurs when a short-circuit accident occurs. By adopting a current limiter, it is possible to limit the overcurrent that flows when a short circuit accident occurs, and the existing circuit breaker can be used as it is.
[0008]
FIG. 7 shows a power receiving and distributing system 500 (a lower range divided by a dotted line) configured using the above-described conventional technology. The commercial system 3 measures, in order from the upstream side, the circuit breaker 5, the current limiting device 6 that performs current limiting operation in response to the input of the current limiting operation command signal, and the current that flows immediately downstream of the current limiting device 6. An overcurrent detector 7 and a commercial bus 8 for outputting a current limiting operation command signal to the current limiter 6 when the value exceeds a predetermined value are connected. General loads 11,..., 11 'are connected to the tributaries of the commercial bus 8 via branch circuit breakers 9,.
[0009]
The private system 13 measures, in order from the upstream side, the circuit breaker 14, the current limiter 15 that performs current limiting operation in response to the input of the current limiting operation command signal, and the current that flows immediately downstream of the current limiter 15. An overcurrent detector 16 for outputting a current limiting operation command signal to the current limiter 15 when the value exceeds a predetermined value, and a self-generated bus 17 are connected. An important load 20,..., 20 ′ is connected to each tributary of the private bus 17 via branch circuit breakers 18,.
[0010]
The commercial bus 8 and the private bus 17 are limited to the current limiter 22 when the current flowing through the linkage point breaker 21, the linkage point current limiter 22, and the linkage point current limiter 22 exceeds a predetermined value. It is connected via an overcurrent detector 23 that outputs a flow operation command signal.
[0011]
When an overcurrent flows, the branch breakers 9,..., 9 ', 18, ..., 18' are set to operate faster than the breakers 5,14. Further, the operating time of the linkage point circuit breaker 21 is set to the same value as the circuit breakers 5 and 14.
[0012]
The overcurrent detectors 7, 16, 23 and the current limiters 6, 15, 22 are provided to reduce the burden on the circuit breaker by limiting the first peak of overcurrent that occurs when a short circuit accident occurs. That is, after the occurrence of overcurrent, before each circuit breaker is activated, the overcurrent detectors 7, 16, 23 output a current limiting operation command signal, and the current limiting devices 6, 15, 22 complete the current limiting operation. It is set to be. The current limiter overcurrent detectors 7, 16, and 23 output a current limiting operation release command signal to the current limiter when the overcurrent is settled.
[0013]
The operation of the power receiving and distributing system having the above configuration will be briefly described.
Usually, the general loads 11,..., 11 ′ are mainly supplied with electric power from the commercial power source 1, and the important loads 20,..., 20 ′ are mainly supplied with electric power from the private generator 12. When a short circuit accident occurs downstream from the commercial bus 8, an overcurrent flows from the commercial power source 1 through the current limiter 6. The overcurrent detector 7 detects the overcurrent and activates the current limiter 6. At the same time, since the overcurrent flows from the self-generated bus 17 through the current limiter 22 at the cooperation point, the overcurrent detector 23 detects the overcurrent and activates the current limiter 22. The overcurrent flowing through the private bus 17 is limited by the current limiter 22 before reaching the first peak. As a result, a rapid voltage drop in the private bus 17 is suppressed, and the operation of the important load 20 is avoided. Further, the action of the current limiter 22 can prevent the circuit breaker 14 from operating and stopping the power supply from the private generator 12.
[0014]
For example, when a short circuit accident occurs in the branch system 10, the branch circuit breaker 9 is activated by an overcurrent that is limited by the operation of the current limiters 6 and 22 and interrupts the electric circuit. Thus, since the overcurrent is not applied to the branch breaker 9 by the action of the current limiters 6 and 22, it is possible to adopt a relatively small breaking capacity. Cost reduction can be achieved.
[0015]
When the branch breaker 9 is activated and the power supply to the general load 11 with the overcurrent limited by the current limiters 6 and 22 is interrupted, the current flowing through the current limiters 6 and 22 is changed to a normal load current. Return. In response to this, the overcurrent detectors 7 and 23 output a current limit release command signal to the current limiters 6 and 22 to cancel the current limit operation of the current limiters 6 and 22. As a result, a series of processes when a short-circuit accident occurs is completed.
[0016]
Since the commercial bus 8 and the private bus 17 are not disconnected, there is no need to adjust the frequency, phase, etc. for re-cooperation, and it is possible to immediately return to the normal state after the completion of the processing when the short-circuit accident occurs. .
[0017]
On the other hand, when a short circuit accident occurs on the in-house power generation system 13 side, the following processing is executed mainly for the purpose of reducing the interrupting duty of the circuit breaker by the current limiter and reducing the interrupting capacity, that is, reducing the cost.
[0018]
When a short circuit accident occurs downstream from the private bus 17, the private current limiter 15 and the linkage point current limiter 22 operate to limit the overcurrent to a small value. For example, when a short circuit accident occurs in the branch system 19, the branch circuit breaker 18 is activated by the limited current. As the overcurrent is interrupted, the current limiting operations of the current limiters 15 and 22 are released and the normal state is restored. In the case of the short-circuit accident, the interrupting duty of the branch circuit breaker 18 is reduced by the current limiters 15 and 22, and a circuit breaker having a smaller capacity can be used as compared with the case where the current limiter is not used. Moreover, since the overcurrent of the private generator 12 can be prevented by the current limiter 15, the stop of the private generator 12 is also avoided. Further, even when a short circuit accident occurs in the self-generated bus 17 itself, the circuit breaker 14 and the cooperation point circuit breaker 21 only have to cut off the current limited by the current limiters 15 and 22, respectively, and the large breaking capacity. This eliminates the need for a circuit breaker and can reduce costs. In either case, a sudden voltage drop of the commercial bus 8 is prevented.
[0019]
[Problems to be solved by the invention]
The power distribution protection system configured by the prior art shown in FIG. 7 can suppress overcurrent caused by a short-circuit accident by using a current limiter, and can reduce the interruption duty required for the series circuit breaker. There is an advantage that an instantaneous voltage drop or a power failure due to the influence of a commercial accident can be prevented from occurring on the private generator side.
[0020]
However, in order to obtain the above-described advantage, the self-power generation side limit until the cooperation point current limiter 22 performs a current-limiting operation due to an overcurrent flowing from the self-power generation bus 17 to the commercial bus 8 when a short-circuit accident occurs on the commercial power source 1 side. It is absolutely required that the flow device 15 does not operate. In the unlikely event that the current limiter 15 operates before the cooperation point current limiter 22 performs the current limiting operation, a high impedance is inserted into the self-generated system 13, and the voltage of the self-generated bus 17 decreases and an important load is generated. Therefore, the continuous operation of 20,.
[0021]
If the operation start timing of the current limiters 6 and 15 is delayed and the current limiter 22 is set to operate earliest, the above problem can be solved. However, for example, when a short-circuit accident occurs on the important load side 20, an overcurrent that is not limited to the short-circuit location of the important load 20 flows for the delay time and is instantaneously supplied to another important load. Voltage drops. In order to prevent a decrease in the voltage supplied to the other important load, the circuit breaker 18 may be operated. In this case, the current limiter 18 is normal to an overcurrent that is not limited. It is necessary to provide a large breaking capacity that can perform a breaking operation. In this case, the meaning of adopting a current limiting device for the purpose of reducing the circuit breaker debt is lost.
[0022]
Therefore, the present invention eliminates the difficulty of controlling the operation timing of each current limiter in a system using both a commercial power source and a private generator, and effectively affects the other system when a short-circuit accident occurs. It is an object of the present invention to provide a power distribution protection system that can be reduced.
[0023]
[Means for Solving the Problems]
  Claim 1In the power distribution protection system,A commercial power source includes a first circuit breaker (5), a first current limiter (6), and a first branch circuit breaker (9) that is one or more loads and upstream of each load. A load (11), a commercial bus connected in sequence, a private generator, a second circuit breaker (14), a second current limiter (15), and one or more loads, each upstream A second load (20) having a second branch breaker (18) on the side, and a self-generated bus connected in sequence, the first current limiter of the commercial bus and the second A portion between the first branch breaker and a portion between the second current breaker and the second branch breaker of the self-bus is a third circuit breaker (21) and a third current limiter ( 22), and a power distribution protection system used in a power distribution system connected via a short circuit accident detection unit and a control unit. A first short-circuit direction detector that detects the occurrence of overcurrent in the line connecting the bus and the self-generated bus via the third circuit breaker and the third current limiter and the direction in which the overcurrent flows ( 26), and when the controller detects that an overcurrent is flowing from the commercial bus to the private bus by the first short circuit direction detector (steps S2, S22, S32), Before the first, second and third circuit breakers are operated, the second and third current limiters are operated (23, Steps S7, S27, S37). When it is detected that overcurrent flows to the commercial bus, the first and third current limiters are operated before the first, second, and third circuit breakers are operated (23, step S4, S24, S34), and the first and second branch breakers are The streamed over current, first, second, and operates faster than the third circuit breakers,It is characterized by that.
[0024]
  Claim 2In the power distribution protection system, the power distribution protection system according to claim 1,When each of the one or more short-circuit direction detectors included in the short-circuit accident detection unit does not detect an overcurrent, it outputs an accident processing completion signal, and the control unit detects all short-circuit directions. The operation of the first, second, and third current limiters is canceled according to the input of the accident processing completion signal from the device (steps S5, S8, S25, S28, S35, S38) (step S6, S9, S26, S29, S36, S39 ) ,It is characterized by that.
[0025]
  Claim 3In the power distribution protection system,Claim 1 or claim 2A power distribution protection system,The short-circuit accident detection unit further includes second and third short-circuit direction detectors (24, 25), and the second short-circuit direction detector (24) generates an overcurrent in a commercial bus, The direction in which the overcurrent flows is detected, and the third short-circuit direction detector (25) detects the occurrence of an overcurrent in the self-generated bus and the direction in which the overcurrent flows. The control unit includes a control device (27), and the control device causes the overcurrent to flow downstream from the commercial bus and the private bus by the second and third short circuit direction detectors. And when the first short circuit direction detector detects that overcurrent is flowing from the commercial bus to the private bus (step S2), the second and third current limiters are operated. (Step S7), and the second and third short circuit direction detectors When it is detected that an overcurrent flows downstream from the private bus and the first short-circuit direction detector detects that an overcurrent flows from the private bus to the commercial bus The first and third current limiters are operated (step S4).It is characterized by that.
[0026]
  Claim 4In the power distribution protection system,Claim 1 or claim 2A power distribution protection system,The short-circuit accident detection unit further includes second and third short-circuit direction detectors (24, 25), and the second short-circuit direction detector (24) generates an overcurrent in a commercial bus, The direction in which the overcurrent flows is detected, and the third short-circuit direction detector (25) detects the occurrence of an overcurrent in the self-generated bus and the direction in which the overcurrent flows. The control unit includes a control device (27 ′) and an overcurrent detector (23), and the control device is connected to the commercial bus and the home by the second and third short-circuit direction detectors. When it is detected that an overcurrent flows downstream from the bus and the first short-circuit direction detector detects that an overcurrent flows from the commercial bus to the private bus (step S22) ), Operating the second current limiter (step S27), and the second, third short circuit It is detected that an overcurrent flows downstream of the commercial bus and the private bus by the wire direction detector, and an overcurrent flows from the private bus to the commercial bus by the first short circuit direction detector. Is detected (step S4, S24), the overcurrent detector detects an overcurrent flowing between the commercial bus and the private bus, A current limiting operation signal for operating the third current limiter in response to detection of an overcurrent;It is characterized by that.
[0027]
  Claim 5In the power distribution protection system,Claim 1 or claim 2A power distribution protection system,The control unit includes a control device (27 ″) and an overcurrent detector (23), and the control device detects overcurrent from a commercial bus to a private bus by a first short-circuit direction detector. When it is detected that it is flowing (step S32) ) The second current limiter is operated (step S37). ) If it is detected by the first short-circuit direction detector that an overcurrent flows from the private bus to the commercial bus, the first current limiter is operated (step S34). ) The overcurrent detector detects an overcurrent flowing between the commercial bus and the private bus, and outputs a current limiting operation signal for operating the third current limiter in response to the detection of the overcurrent. Is,It is characterized by that.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
(1) Summary of the invention
The power distribution and protection system according to the present invention is a power distribution system using both a commercial power source and a private generator. The commercial power source is connected to the commercial power source via a first current limiter that performs a current limiting operation in response to an input of a current limiting operation command signal. A commercial bus connected to the private power generator via a second current limiter, and a private bus connected to the commercial power bus via a third current limiter, and the commercial bus. A short-circuit accident that detects the occurrence of a short-circuit accident downstream from the private bus and outputs an accident information signal indicating the occurrence of the short-circuit accident and whether the short-circuit accident occurred on the commercial bus or the private bus Based on the accident information signal output from the detection unit and the short-circuit accident detection unit, it is determined whether a short-circuit accident has occurred in either the commercial bus or the private bus, and the bus-side current limiter specified by the determination And at least the third current limiter Characterized in that it comprises a control device for feeding a current limiting operation command signal to the first or second current limiting device comprising a current limiter. By adjusting the operation timing of the current limiter at the time of occurrence of a short-circuit accident using the above-described control device, it is possible to effectively prevent a sudden decrease in potential in another system when a short-circuit accident occurs. Moreover, by realizing an appropriate current limiting operation, it is possible to reduce the interrupting duty required for each circuit breaker when a short circuit accident occurs.
[0033]
In addition, a first circuit breaker, a second circuit breaker, and a third circuit breaker are provided in the vicinity of each of the first current limiter, the second current limiter, and the third current limiter, and the short circuit accident detection unit. The time required for a given current limiter to complete the current-limiting operation after detecting a short-circuit accident is shorter than the time required for any of the circuit breakers to operate from the occurrence of the short-circuit accident. It is characterized by setting. By adopting this configuration, it is possible to prevent the malfunction of the breaker of the other system before the accident handling of the system causing the short circuit accident is completed.
Hereinafter, Embodiments 1 to 3 of the power distribution protection system having the above features will be described in order with reference to the accompanying drawings.
[0034]
(2) Embodiment 1
(2-1) System configuration
FIG. 1 shows a configuration of a power distribution protection system 100 according to the first embodiment. The same components as those in the conventional power distribution protection system 500 described with reference to FIG. The system 100 includes a commercial system 2 extending from a commercial power source 1 to each consumer, a commercial system 3 in one consumer connected via a power receiving end 4, and a private generator provided in the consumer. 12 is composed of wiring of a self-generated system 13 extending from 12 (lower range divided by a dotted line).
[0035]
The commercial system 3 measures, in order from the upstream side, the circuit breaker 5, the current limiting device 6 that performs current limiting operation in response to the input of the current limiting operation command signal, the current and voltage that flow through the current limiting device 6, and the measured current The occurrence of an overcurrent is detected from the value, the direction in which the overcurrent flows is identified from the phase difference between the current and the voltage, and an accident information signal indicating the occurrence of the overcurrent and the direction in which the overcurrent flows is output to the control device 27. The short-circuit direction detector 24 and the commercial bus 8 are connected. A branch breaker 9,..., 9 ′ is connected to the commercial bus 8, and at the end of a line (branch system 10,..., 10 ′) extending from the downstream of the branch breaker 9,. The general loads 11,..., 11 ′ are connected.
[0036]
The private system 13 measures, in order from the upstream side, the circuit breaker 14, the current limiter 15 that performs a current limiting operation in response to the input of the current limiting operation command signal, the current and voltage flowing through the current limiter 15, and the current measurement. The occurrence of an overcurrent is detected from the value, the direction in which the overcurrent flows is identified from the phase difference between the current and the voltage, and an accident information signal indicating the occurrence of the overcurrent and the direction in which the overcurrent flows is output to the control device 27. A short-circuit direction detector 25 and a private bus 17 are connected. Branch breakers 18,..., 18 ′ are connected to the private bus 17, and at the end of a line (branch system 19,..., 19 ′) extending from the downstream of the branch breakers 18,. , 20 ′ are connected to important loads (loads connected by a customer to operate uninterrupted).
[0037]
The commercial bus 8 and the private bus 17 measure the current flowing through the linkage point breaker 21, the linkage point current limiter 22, and the current limiter 22, detect the occurrence of overcurrent from the measured value, and overcurrent Are connected to each other via a short-circuit direction detector 26 that outputs to the control device 27 an accident information signal indicating the occurrence of the overcurrent and the direction in which the overcurrent flows.
[0038]
The circuit breakers 5 and 14 are provided with overcurrent detection means, and cut off energization when a current exceeding a predetermined value flows for a predetermined time T. The circuit breakers 9,..., 9 ', 18,..., 18' are also provided with overcurrent detection means, and the current supply is interrupted when a current exceeding a predetermined value flows for a predetermined time T '. The operating characteristics of the circuit breakers 5 and 14 and the branch circuit breakers 9,..., 9 ', 18, ..., 18' are set so as to be a timed cooperative method that is a normal power distribution protection type. That is, when an overcurrent flows, the branch breakers 9, ..., 9 ', 18, ..., 18' operate faster than the breakers 5 and 14 (that satisfies the relationship of T '<T). To do. However, the time required to complete the normal circuit breaker operation is a period in which the alternating current is cycled, and the branch circuit breakers 9,..., 9 ′, 18,. I can't do it. In addition, the thing with the same operation time T as the circuit breakers 5 and 14 is employ | adopted for the cooperation point circuit breaker 21. FIG.
[0039]
The short-circuit direction detectors 24, 25, and 26 determine that an overcurrent has occurred when a measuring device that measures current and voltage flowing through the system and a measured value of the current by the measuring device exceeds a predetermined threshold value. And a DSP (Digital Signal Processor) that specifies the direction of overcurrent flow from the phase difference between the measured current and voltage and outputs a digital accident information signal indicating the occurrence of the overcurrent and the flow direction. The The short-circuit direction detectors 24, 25, and 26 output an accident information signal after the time t1 has elapsed since the occurrence of an overcurrent.
Further, the short-circuit direction detectors 25, 26, 27 output an accident processing completion signal to the control device 27 when the current flowing through the system returns from the overcurrent to the normal load current.
[0040]
The control device 27 includes an arithmetic processing unit (hereinafter referred to as CPU) 27a, a ROM 27b that stores a signal processing program, and a RAM 27c that is used as a work area when the signal processing program is executed by the CPU 27a. The CPU 27a determines the content of the short-circuit accident based on the accident information signal from the short-circuit direction detectors 24, 25, 26, or recognizes the completion of the accident processing based on the accident processing completion signal, and outputs the accident information signal. A current limiting operation command signal or a current limiting operation release command signal is output to a predetermined current limiter 6, 15, 22 after a time t2 from receiving. The contents of the signal processing program will be described later.
[0041]
The current limiters 6, 15 and 22 are provided to reduce the burden on the circuit breaker by limiting the first peak of overcurrent that occurs when a short circuit accident occurs. The current limiters 6, 15, and 22 complete the current limiting operation after the elapse of time t <b> 3 after receiving the current limiting operation command signal from the control device 27.
Further, the current limiters 6, 15, and 22 release the current limiting operation in response to the input of the current limiting operation release command signal.
[0042]
Before the circuit breaker that operates against the overcurrent limited by the current limiter is damaged, the overcurrent flows through each circuit breaker to ensure that the current limiting operation by the necessary current limiter is completed. The short-circuit direction detectors 24, 25, 26, the control device 27, the current limiters 6, 15 so that the total of the times t1, t2, t3 is significantly smaller than the times T, T ′ required to operate. , 22 and circuit breakers 5, 9, ..., 9 ', 14, 18, ..., 18', 21 are selected.
[0043]
(2-2) Short-circuit accident handling
FIG. 2 is a flowchart of signal processing executed by the control device 27 when a short circuit accident occurs. Hereinafter, referring to the configuration of the power distribution protection system shown in FIG. 1 and the signal processing flow of the control device 27 shown in FIG. 2, it is executed when a short circuit accident occurs in the power distribution protection system 100 configured as described above. Accident handling will be explained for each location where a short circuit accident occurs.
[0044]
(2-2-1) Short circuit accident in the branch system on the commercial power supply side
A case where a short-circuit accident occurs in any one of the branch systems 10,..., 10 ′ on the commercial power source 1 side, for example, the branch system 10 will be described. With the occurrence of the short circuit accident, an overcurrent flows from the commercial power supply 1 through the current limiter 6 that is not performing the current limiting operation. At this time, the short circuit direction detector 24 detects a short circuit accident on the downstream side of the current limiter 6 and outputs an accident information signal indicating the content to the control device 27. Further, with the occurrence of the short circuit accident, the overcurrent flows from the private power generator 12 through the private power generation side current limiter 15, the private power generation bus 17, and the cooperation point current limiter 22 into the short circuit accident location of the branch system 10. The short circuit direction detector 25 on the private generator 12 side detects a short circuit accident on the downstream side of the current limiter 15, and outputs an accident information signal representing this to the control device 27. Moreover, the cooperation point short circuit direction detector 26 detects a short circuit accident on the commercial power supply 1 side on the left side of the current limiter 22 in the drawing, and outputs an accident information signal indicating this to the control device 27.
[0045]
The control device 27 determines that a short-circuit accident has occurred when an accident information signal is input from the short-circuit direction detectors 24, 25, and 26 (YES in step S1 in FIG. 2), and the short-circuit direction detectors 24, 25, The accident content is determined based on the content of the accident information signal from 26 (step S2 in FIG. 2). Specifically, in the control device 27, both of the accident information signals from the short-circuit direction detectors 24 and 25 indicate a short-circuit accident on the downstream side, and the accident information signal from the short-circuit direction detector 26 is a short-circuit on the commercial power source 1 side. Based on the fact that it represents an accident, it is determined that this is a short circuit accident in the system on the commercial power source 1 side (YES in step S3 in FIG. 2), and the commercial side current limiter 6 and the linkage point current limiter 22 are determined. A current limiting operation command signal is output to (step S4 in FIG. 2). In response to the input of the current limiting operation command signal, the current limiters 6 and 22 complete the current narrowing before the overcurrent generated by the short-circuit accident reaches the peak value. Hereinafter, the overcurrent narrowed down by the current limiters 6 and 22 is referred to as an accident current.
[0046]
In order to simplify the system and speed up the process, the short-circuit direction detectors 24 and 25 are omitted, only the short-circuit direction detector 26 is provided, and a short-circuit accident represented by the accident information signal from the short-circuit direction detector 26 is provided. The process of step S3 may be executed based only on the direction in which it occurred.
[0047]
When a short circuit accident occurs in the branch system 10 on the commercial power source 1 side, the branch circuit breaker 9 set to operate faster than the circuit breaker 5 is activated according to the accident current, and the accident current is shorted. Shut off from flowing into. Due to the action of the circuit breaker 9, the current flowing in the system returns to the normal load current. The short-circuit direction detectors 24 and 26 output an accident processing completion signal to the control device 27 when the current supplied from the commercial power source 1 returns to the normal load current. In response to the input of the accident processing completion signal (YES in step S5 in FIG. 2), the control device 27 outputs a current limit release command signal to the current limiters 6 and 22 (step S6). With the above processing, a series of accident processing by the control device 27 is completed.
[0048]
The current flowing from the private bus 17 to the commercial bus 8 is suppressed to a small value by the function of the linked point current limiter 22. At this time, the home-side current limiter 15 is not current-limiting, and the potential at the home bus 17 does not drop rapidly. This guarantees continuous operation of the important loads 20,.
Moreover, since the overcurrent flowing from the private generator 12 is also suppressed to a normal load current by the linkage point current limiter 22, the circuit breaker 14 does not operate and the private generator 12 can be prevented from stopping.
[0049]
(2-2-2) Short circuit accident at the commercial bus on the commercial power supply side
Next, a case where a short circuit accident occurs in the commercial bus 8 on the commercial power source 1 side will be considered. In this case, the short circuit direction detectors 24, 25, and 26 output the same accident information signal as when a short circuit accident occurs in the branch system 10. The control device 27 detects the occurrence of a short circuit accident in response to the input of the accident information signal (YES in step S1 in FIG. 2), and determines the accident content based on the content of the input accident information signal (FIG. 2). 2 step S2). Specifically, in the control device 27, both of the accident information signals from the short-circuit direction detectors 24 and 25 indicate a short-circuit accident on the downstream side, and the accident information signal from the short-circuit direction detector 26 is a short-circuit on the commercial power source 1 side. Based on the fact that the accident is represented, it is determined that this is a short circuit accident in the system on the commercial power source 1 side (YES in step S3 in FIG. 2), and the commercial side current limiter 6 and the cooperation point current limiter 22 are detected. To limit the overcurrent flowing into the commercial bus 8 (step S4 in FIG. 2). The commercial-side circuit breaker 5 and the linkage point current limiter 21 are activated by the overcurrent that has been narrowed down. As a result, the current supplied from the private generator 12 returns to the normal load current. Accordingly, the short-circuit direction detectors 24 and 26 output an accident processing completion signal to the control device 27. In response to the input of the accident processing completion signal (YES in step S5 in FIG. 2), the control device 27 outputs a current limit release command signal to the current limiters 6 and 22 (step S6 in FIG. 2). The accident processing is completed by the above processing.
[0050]
The current flowing from the private bus 17 to the commercial bus 8 is suppressed to a small value by the function of the linked point current limiter 22. At this time, the home-side current limiter 15 is not current-limiting, and the potential at the home bus 17 does not drop rapidly. This guarantees continuous operation of the important loads 20,. Further, since the overcurrent flowing from the private generator 12 is also suppressed to the normal load current by the linkage point current limiter 22, the circuit breaker 14 does not operate and the private generator 12 can be stopped.
[0051]
(2-2-3) Short-circuit accident on the private generator side
Next, a case where a short circuit accident occurs on the private generator 12 side will be described. If a short circuit accident occurs on the self-powered system 13 side, instead of preventing the voltage drop or power outage to the important loads 20, ..., 20 ', the circuit breaker's duty to shut down the circuit breaker is reduced and cut off. The following processing is executed for the purpose of reducing the capacity, that is, reducing the cost.
[0052]
When a short circuit accident occurs on the private generator 12 side, an overcurrent flows from the private generator 12 through the current limiter 15. For this reason, the short circuit direction detector 25 outputs an accident information signal indicating a short circuit accident downstream of the current limiter 15 to the control device 27. At the same time, overcurrent flows from the commercial power source 1 through the commercial-side current limiter 6, the commercial bus 8, and the linked point current limiter 22 into the private bus 17. The short circuit direction detector 24 of the commercial side current limiter 6 outputs an accident information signal indicating a short circuit accident on the downstream side of the current limiter 6 to the control device 27. The short circuit direction detector 26 of the linkage point current limiter 22 outputs to the control device 27 an accident information signal indicating a short circuit accident on the home side on the right side of the current limiter 22 in the drawing.
[0053]
The control device 27 determines that a short-circuit accident has occurred due to the input of the accident information signal from the short-circuit direction detectors 24, 25, and 26 (YES in step S1 in FIG. 2), and the short-circuit direction detectors 24, 25, and 26 The accident content is determined based on the content of the accident information signal (step S2 in FIG. 2). Specifically, in the control device 27, both the accident information signals from the short-circuit direction detectors 24 and 25 indicate a short-circuit accident on the downstream side, and the accident information signal from the short-circuit direction detector 26 is on the private generator 12 side. Therefore, it is determined that this is a short-circuit accident in the system on the private generator 12 side (NO in step S3 in FIG. 2), and the fault current limiter 15 on the private generator 12 side and cooperation are determined. A current limiting operation command signal is output to the point current limiter 22 (step S7 in FIG. 2). In response to the input of the current limiting operation command signal, the current limiters 15 and 22 narrow down the current before the overcurrent generated by the short circuit accident reaches the peak value.
[0054]
The current flowing from the commercial bus 8 to the private bus 17 is suppressed to be small by the current limiting operation of the current limiters 15 and 22. At this time, since the commercial side current limiter 6 is not operating, it is possible to prevent the voltage supplied to the commercial bus 8 from being lowered. For example, when the short-circuit location on the private generator 12 side is in the branch system 19, the branch breaker 18 located immediately upstream of the short-circuit location cuts off the accident current that is narrowed down by the operation of the current limiters 15 and 22. To do. When the fault current is interrupted, the currents of the current limiters 15 and 22 return to the load current, so the short circuit direction detectors 25 and 26 output an accident processing completion signal to the control device 27. In response to the input of the accident processing completion signal (YES in step S8 in FIG. 2), the control device 27 outputs a current limit release command signal to the current limiters 15 and 22 (step S9 in FIG. 2). Cancel the operation.
[0055]
When the accident location is on the private bus 17, the circuit breaker 14 and the cooperation point circuit breaker 21 are operated by the current limited by the current limiters 15 and 22. Even in this case, power supply to the general loads 11,..., 11 'on the commercial power source 1 side is continued. Since the currents of the current limiters 15 and 22 return to the load current by the operation of the circuit breakers 14 and 21, the short-circuit direction detectors 25 and 26 output an accident processing completion signal to the control device 27. In response to the input of the accident processing completion signal (YES in step S8 in FIG. 2), the control device 27 outputs a current limit release command signal to the current limiters 15 and 22 (step S9 in FIG. 2). Cancel the operation.
[0056]
(3) Embodiment 2
FIG. 3 is a diagram illustrating a configuration of the power distribution protection system 200 according to the second embodiment. The same components as those in the power distribution protection system 100 shown in FIG. 1 are denoted by the same reference numerals, and a duplicate description is omitted here. 1 differs from the power distribution and protection system 100 according to the first embodiment shown in FIG. 1 in addition to the directional short circuit current limiter 26 in addition to the overcurrent detector 23 used in the conventional power distribution and protection system 500. It is to be. That is, in the power distribution protection system 200, when a short circuit accident occurs on either the commercial power source 1 side or the private generator 12 side, the overcurrent detector 23 is not dependent on the current limiting operation signal from the control device 27 ′. The operation of the current limiter 22 is directly controlled. As a result, the current flowing through the connection point between the commercial bus 8 and the private bus 17 can be quickly narrowed down, and the decrease in the potential flowing through the non-short-circuited system can be prevented more quickly. The overcurrent detector 23 outputs a current limit release command signal to release the current limiting operation of the current limiter 22 when a predetermined circuit breaker is activated and the overcurrent returns to the normal load current.
[0057]
FIG. 4 is a flowchart of signal processing executed by the control device 27 ′ included in the power distribution protection system 200. The last digit number of each step number corresponds to the corresponding step number in the flowchart of the accident process executed by the control device 27 included in the power distribution protection system 100 shown in FIG. The control device 27 ′ outputs a current limiting operation command signal only to the current limiter 6 on the commercial power source 1 side in step S24, and to the current limiter 15 on the private generator 12 side in step S27. However, it is different from the accident process executed by the control device 27 in the power receiving and distribution protection system 100 in that the current limiting operation command signal is output only for the power distribution protection system 100. By adopting this configuration, the processing content executed by the control device is simplified, and the processing can be speeded up.
[0058]
(4) Embodiment 3
FIG. 5 is a diagram illustrating a configuration of a power distribution protection system 300 according to the third embodiment. The same components as those in the power distribution protection system 200 shown in FIG. 3 are denoted by the same reference numerals, and redundant description is omitted here. The difference from the power distribution protection system 200 shown in FIG. 3 is that the short-circuit direction detectors 24 and 25 are removed. The control device 27 ″ identifies the system that has caused the short-circuit accident based on the information on the direction in which the overcurrent flows represented by the accident information signal from the short-circuit direction detector 26. Specifically, the overcurrent is on the commercial power source 1 side. When the current flows to the current generator 1, it is determined that a short circuit accident has occurred on the commercial power supply 1 side, and a current limiting operation signal is output to the current limiter 6. On the other hand, when an overcurrent flows to the private generator 12 side Then, it is determined that a short circuit accident has occurred on the private generator 12 side, and a current limiting operation signal is output to the current limiter 15.
[0059]
FIG. 6 is a flowchart of the accident process executed by the control device 27 ″ included in the power distribution protection system 300. The last digit of each step number is the control device 27 ′ included in the power distribution protection system 200 shown in FIG. This corresponds to the last digit of the corresponding step number in the flowchart of the accident processing executed by the controller 27 ". In the control device 27", the overcurrent represented by the accident information signal from the short-circuit direction detector 26 in the accident content determination processing in step S22. The system that caused the short-circuit accident is identified based on the information on the direction of flow. In addition, in step S34, a current limiting operation command signal is output only to the current limiter 6 on the commercial power source 1 side, and in step S37, only to the current limiter 15 on the private generator 12 side. The point that the current limiting operation command signal is output is the same as the power distribution protection system 200. By adopting this configuration, it is possible to further simplify the processing contents executed by the control device 27 ″ and increase the processing speed, and also to reduce the cost by simplifying the system configuration.
[0060]
【The invention's effect】
  In the power distribution protection system according to any one of claims 1 to 5, by adjusting the operation timing of the current limiter at the time of occurrence of a short circuit accident, it is possible to effectively reduce the potential in other systems when the short circuit accident occurs. Prevent it. Moreover, by realizing an appropriate current limiting operation, it is possible to reduce the interrupting duty required for each circuit breaker when a short circuit accident occurs. In addition, the time required for the predetermined current limiter to complete the current limiting operation after the short-circuit accident detection unit detects the short-circuit accident is the time required for any of the circuit breakers to operate from the occurrence of the short-circuit accident. By setting it to be shorter than that, it is possible to prevent the malfunction of the circuit breakers of other systems before the accident handling of the system causing the short circuit accident is completed.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a power distribution protection system according to a first embodiment.
FIG. 2 is a signal processing flowchart executed by the control device;
FIG. 3 is a diagram illustrating a configuration of a power distribution protection system according to a second embodiment.
FIG. 4 is a flowchart of signal processing executed by a control device.
FIG. 5 is a diagram showing a configuration of a power distribution protection system according to a third embodiment.
FIG. 6 is a flowchart of signal processing executed by the control device.
FIG. 7 is a diagram showing a configuration of a conventional power distribution protection system.
[Explanation of symbols]
1 commercial power source, 2 commercial system, 3 commercial system in customer, 4 receiving end, 5, 14, 21 circuit breaker, 6, 15, 22 current limiter, 8 commercial bus, 9 ... 9 ', 18 ... 18' branch Circuit breaker, 10 ... 10 ', 19 ... 19' Branch system, 11 ... 11 'General load, 20 ... 20' Important load, 27, 27 ', 27 "control device.

Claims

A commercial power source includes a first circuit breaker (5), a first current limiter (6), and a first branch circuit breaker (9) that is one or more loads and upstream of each load. A load (11), a commercial bus connected in sequence, a private generator, a second circuit breaker (14), a second current limiter (15), and one or more loads, each upstream A second load (20) having a second branch breaker (18) on the side, and a self-generated bus connected in sequence, the first current limiter of the commercial bus and the second A portion between the first branch breaker and a portion between the second current breaker and the second branch breaker of the self-bus is a third circuit breaker (21) and a third current limiter ( 22), and a power distribution protection system used in a power distribution system connected via
Including a short-circuit accident detection unit and a control unit,
The short-circuit accident detection unit is configured to generate an overcurrent in a line connecting the commercial bus and the private bus via a third circuit breaker and a third current limiter, and a direction in which the overcurrent flows. A first short-circuit direction detector (26) for detecting,
When it is detected by the first short circuit direction detector that an overcurrent is flowing from the commercial bus to the private bus (steps S2, S22, S32), the first, second, third Before the circuit breaker operates, the second and third current limiters are operated (23, steps S7, S27, S37), and the first short circuit direction detector causes an overcurrent from the private bus to the commercial bus. When the flow is detected, the first and third current limiters are operated before the first, second and third circuit breakers are operated (23, steps S4, S24 and S34). ,
The first and second branch circuit breakers operate faster than the first, second and third circuit breakers due to the overcurrent limited by the current limiter.
A power distribution protection system characterized by that.

When each of the one or more short-circuit direction detectors included in the short-circuit accident detection unit does not detect an overcurrent, an accident processing completion signal is output.
The control unit operates the first, second, and third current limiters in response to input of accident processing completion signals from all short-circuit direction detectors (steps S5, S8, S25, S28, S35, and S38). (Steps S6, S9, S26, S29, S36, S39 ) ,
The power distribution protection system according to claim 1.

The short-circuit accident detection unit further includes second and third short-circuit direction detectors (24, 25),
The second short-circuit direction detector (24) detects the occurrence of overcurrent in the commercial bus and the direction in which the overcurrent flows;
The third short-circuit direction detector (25) detects the occurrence of an overcurrent in the private bus and the direction in which the overcurrent flows,
The control unit includes a control device (27),
In the control device, it is detected by the second and third short circuit direction detectors that an overcurrent is flowing downstream from the commercial bus and the private bus, and from the commercial bus by the first short circuit direction detector. When it is detected that an overcurrent flows to the private bus (step S2), the second and third current limiters are operated (step S7). The second and third short circuit direction detectors Detects that an overcurrent flows downstream from the commercial bus and the private bus, and the first short circuit direction detector detects that an overcurrent flows from the private bus to the commercial bus. If so, the first and third current limiters are operated (step S4).
The power distribution protection system according to claim 1 or 2 .

The short-circuit accident detection unit further includes second and third short-circuit direction detectors (24, 25),
The second short-circuit direction detector (24) detects the occurrence of overcurrent in the commercial bus and the direction in which the overcurrent flows;
The third short-circuit direction detector (25) detects the occurrence of an overcurrent in the private bus and the direction in which the overcurrent flows,
The control unit includes a control device (27 ′) and an overcurrent detector (23),
In the control device, it is detected by the second and third short circuit direction detectors that an overcurrent is flowing downstream from the commercial bus and the private bus, and from the commercial bus by the first short circuit direction detector. When it is detected that overcurrent flows to the private bus (step S22), the second current limiter is operated (step S27), and the commercial bus is detected by the second and third short circuit direction detectors. When it is detected that an overcurrent flows downstream from the private bus and the first short-circuit direction detector detects that an overcurrent flows from the private bus to the commercial bus The first current limiter is operated (steps S4 and S24).
The overcurrent detector detects an overcurrent flowing between the commercial bus and the private bus, and outputs a current limiting operation signal for operating the third current limiter according to the detection of the overcurrent.
The power distribution protection system according to claim 1 or 2 .

The control unit includes a control device (27 ″) and an overcurrent detector (23),
The control device, when the fact that overcurrent flows from the commercial bus to house power bus detected by the first short-circuit direction detector (step S32), to operate the second current limiting device (step S37) one And when the first short circuit direction detector detects that overcurrent is flowing from the private bus to the commercial bus, the first current limiter is operated (step S34 ) .
The overcurrent detector detects an overcurrent flowing between the commercial bus and the private bus, and outputs a current limiting operation signal for operating the third current limiter according to the detection of the overcurrent.
The power distribution protection system according to claim 1 or 2 .