JP3956794B2

JP3956794B2 - Parallel operation current detector for uninterruptible power supply and current detection method

Info

Publication number: JP3956794B2
Application number: JP2002230724A
Authority: JP
Inventors: 一喜梅沢
Original assignee: Fuji Electric Holdings Ltd
Current assignee: Fuji Electric Co Ltd
Priority date: 2002-08-08
Filing date: 2002-08-08
Publication date: 2007-08-08
Anticipated expiration: 2022-08-08
Also published as: JP2004072928A

Description

【０００１】
【発明の属する技術分野】
この発明は、直送給電回路または無停電電源装置が並列運転する際に必要とする電流を検出する装置と、その電流検出方法に関する。
【０００２】
【従来の技術】
複数の無停電電源装置を並列運転する場合に、各無停電電源装置がその出力電流を均等に分担する必要があることは周知である。そのために、並列運転中の各無停電電源装置の出力電流を別個に計測し、これらを合計し、この合計値を運転台数で割り算する手順の計算回路を設ける。また、並列運転中に故障などで無停電電源装置の運転台数が変化すれば、運転を継続している無停電電源装置の分担電流も変化するが、分担電流の計算がこのような状況の変化に速やかに対応できるようにしておく必要もある。更に、このようにして得られた平均電流値を目標値にして、各無停電電源装置はその出力電流を目標値に一致させるべく制御をするのであるから、この平均電流値は正しくなければならない。
【０００３】
図４は直送切り換え回路バックアップ方式無停電電源装置の電流検出の従来例を示した回路図である。図示のように、無停電電源装置２と直送給電回路３とは無瞬断切り換え装置４を介して並列に接続されていて、保守用開閉器７を介して母線１に接続される。この母線１には、図示は省略しているが、同じ構成の無停電電源装置を複数接続することで、並列運転を行う。
【０００４】
無瞬断切り換え装置４は交流スイッチ４Ａと直送用開閉器４Ｂと出力用開閉器４Ｃで構成されていて、通常は交流スイッチ４Ａと直送用開閉器４Ｂはオフで出力用開閉器４Ｃをオンにすることで、無停電電源装置２が保守用開閉器７を介して母線１へ交流電力を供給するのであるが、このときの無停電電源装置２の出力と直送給電回路３の出力は同期状態を維持しているから、無停電電源装置２が故障したり過電流になれば、即座に交流スイッチ４Ａをオンにして、母線１への交流電力の供給を、無瞬断で且つショックを生じることなしで、無停電電源装置２から直送給電回路３へ切り換えることができる。直送給電回路３の給電中は無停電電源装置２が直送給電回路３ど同期した電圧を発生してスタンバイしており、切り換え指令に従って直送給電回路３から無停電電源装置２への電力の切り換えが無瞬断でなされる。
【０００５】
複数の無停電電源装置２が並列運転しているとき、各無停電電源装置２の出力電流を均等化する必要がある。そこで保守用開閉器７の回路に設けた主変流器６が検出する電流を、他の無停電電源装置の主変流器６が検出する電流と共に電流加算器４１へ入力してこれらの合計電流を計算する。一方で出力用開閉器４Ｃのオン信号を他の無停電電源装置の出力用開閉器４Ｃのオン信号と共に運転台数カウンタ４２へ入力することで、並列運転中の無停電電源装置の台数を求める。除算器４３は合計電流値を運転台数で除算することで１台当たりの平均電流を計算する。制御装置８はこの平均電流を指令値にして、出力変流器５が検出する当該無停電電源装置２の出力電流をこの平均電流に一致させる制御を行う。並列運転中の各無停電電源装置は、すべてがこの平均電流を指令値にした制御を行うから、全無停電電源装置を同一出力電流で運転させることができる。
【０００６】
また、図示は省略しているけれども、直送給電回路３で給電しているときの合計電流を電流加算器４１で知ることができるし、直送用開閉器４Ｂがオンしている台数から、自動または手動で直送給電回路の１回路当たりの平均電流を知ることもできる。
【０００７】
【発明が解決しようとする課題】
図４に図示の従来例回路において、無停電電源装置の並列運転中は除算器４３が各無停電電源装置へ電流指令値を与えるのであるが、平均電流を算出する各回路が誤動作して正しい電流指令値が得られないと、すべての無停電電源装置が制御不能状態に陥る危険があるが、それにもかかわらず、算出した電流指令値が正しいか否かを確認できない不具合を生じる。
【０００８】
また、例えば３回路並列で給電中の直送給電回路の１回路当たりの出力電流が100Aであって、スタンバイしている無停電電源装置の１台当たりの電流容量が120Aであるとすると、３回路並列の直送給電回路から３台並列の無停電電源装置へ切り換わるときは全く問題無いが、故障などのためにスタンバイしている無停電電源装置が２台しかない場合は、１台が150Aの電流を分担することになって過電流になるから、再び直送給電回路からの給電に戻ってしまう不具合を生じる。すなわち従来設備では、並列運転中の無停電電源装置の一台当たりの平均電流の算出はできても、直送給電回路の１回路あたりの平均電流の算出や、スタンバイ状態にある無停電電源装置が並列運転したならば分担することになるであろう１台当たりの平均電流を予測できない不具合があった。
【０００９】
そこでこの発明の目的は、並列運転中の無停電電源装置の電流指令値となる平均電流を二重に算出して相互チェックを可能にすると共に、直送給電回路の平均電流と、スタンバイ状態にある無停電電源装置が並列運転する際の平均電流が算出できるようにすることにある。
【００１０】
【課題を解決するための手段】
前記の目的を達成するために、この発明の無停電電源装置の並列運転電流検出装置とその電流検出方法は、
直送給電回路の出力側に備えた直送用開閉器と、無停電電源装置の出力側に備えた出力用開閉器とを結合し、この結合点と母線との間に保守用開閉器を設けて直送切り換え回路バックアップ方式無停電電源装置を構成し、これの複数組を母線に接続することで構成される無停電電源装置の並列運転装置において、
前記出力用開閉器の回路の電流を検出する出力変流器と、該出力変流器の二次巻線に直接または補助変流器を介して接続してその入力信号を所望のレベルの信号に変換する第１信号変換器と、前記保守用開閉器の回路の電流を検出する第１変流器と第２変流器と、該第１変流器の二次巻線に接続して、前記出力用開閉器と前記保守用開閉器の両者がオンで且つ前記無停電電源装置が運転状態のときにオンとなる第１スイッチと、該第１スイッチの出力側と、他の各無停電電源装置に属するそれぞれの第１スイッチの出力側とを接続する第１スイッチ接続線と、前記第１変流器の二次巻線に抵抗を介して接続する第１補助変流器と、該第１補助変流器の二次巻線に接続してその入力信号を所望のレベルの信号に変換する第２信号変換器と、前記第２変流器の二次巻線に接続して、前記直送用開閉器または前記出力用開閉器のいずれかがオンで且つ前記保守用開閉器がオンのときにオンとなる第２スイッチと、該第２スイッチの出力側と、他の各無停電電源装置に属するそれぞれの第２スイッチの出力側とを接続する第２スイッチ接続線と、この第２変流器の二次巻線に接続して、前記無停電電源装置が運転状態のときにオンとなる第３スイッチと、該第３スイッチの出力側に、抵抗を介して接続する第２補助変流器と、該第２補助変流器の二次巻線に接続してその入力信号を所望のレベルの信号に変換する第３信号変換器と、前記第２変流器の二次巻線に接続して、この二次巻線の電圧が所定値を越えると導通して当該二次巻線を短絡する半導体素子と、を備える。
【００１２】
前記第２信号変換器の出力信号と比較するべき並列運転中の無停電電源装置１台当たりの平均出力電流信号は、直送切り換え回路バックアップ方式無停電電源装置の直送給電回路と無停電電源装置の出力回路とを結合した回路に第２変流器を設置し、並列運転中の各無停電電源装置のそれぞれに属する各第２変流器の二次巻線同士を第２スイッチ接続線で接続すると共に、並列運転中の各無停電電源装置に属する前記第２変流器の二次巻線のそれぞれに抵抗を介して第２補助変流器を接続し、該第２補助変流器の二次巻線のそれぞれに別個に接続した第３信号変換器から検出する。
【００１３】
直送給電回路から無停電電源装置へ切り換わったときに並列運転となるべき台数の無停電電源装置１台当たりの平均出力電流信号は、直送切り換え回路バックアップ方式無停電電源装置の直送給電回路と無停電電源装置の出力回路とを結合した回路に第２変流器を設置し、並列運転中の各直送給電回路のそれぞれに属する各第２変流器の二次巻線同士を第２スイッチ接続線で接続すると共に、動作中の各無停電電源装置に属する第２変流器の二次巻線のそれぞれに抵抗を介して第２補助変流器を接続し、該第２補助変流器の二次巻線のそれぞれに別個に接続した第３信号変換器から検出する。
【００１４】
【発明の実施の形態】
図１は本発明の第１実施例を表した回路図であるが、この第１実施例回路に記載している主回路部分である母線１，無停電電源装置２，直送給電回路３，無瞬断切り換え装置４，出力変流器５，主変流器６および保守用開閉器７の名称・用途・機能は、図４で既述の従来例回路と同じであるから、同じ部分の説明は省略する。
【００１５】
この第１実施例回路では、主変流器６の二次巻線に第１変流器１１と第２変流器２１を設置しているが、これら第１変流器１１と第２変流器２１の代わりに主変流器６と同種の変流器を保守用開閉器７の回路に挿入しても同じである。この第１変流器１１の二次巻線には抵抗１５を介して第１補助変流器１６を設置するが、この第１補助変流器１６の二次巻線には信号変換器としての第１電流電圧変換器１７を接続する。さらに第１変流器１１の二次巻線には第１スイッチ１２を設け、この第１スイッチ１２の出力側に接続した第１スイッチ接続線１３が、他の無停電電源装置に設けている第１スイッチ１２の出力側に接続されている。ここで第１スイッチ１２は、出力用開閉器４Ｃと保守用開閉器７とがオンで且つ無停電電源装置２が動作中のときにオンとなる。第１スイッチ１２がオンすると、第１電流電圧変換器１７には並列運転中の無停電電源装置の出力電流の１台当たりの平均値が現れる。また出力用開閉器４Ｃの二次巻線に設けた出力補助変流器３１の二次巻線に第３電流電圧変換器３２を接続すると無停電電源装置２の出力電流を検出できる。よって制御装置８において、第１補助変流器１６の出力（無停電電源装置の平均電流）を指令値にして、第３電流電圧変換器３２の出力である無停電電源装置２の出力電流を指令値に一致させる制御が行える。
【００１６】
なお第１スイッチ１２をオフにすれば、保守用開閉器７の回路の電流を検出できる。
主変流器６の二次巻線に設けた第２変流器２１の二次巻線には、第３スイッチ２４と抵抗２５を介して第２補助変流器２６が設置されており、この第２補助変流器２６の二次巻線には信号変換器としての第２電流電圧変換器２７を接続している。更に第２変流器２１の二次巻線には第２スイッチ２２を設け、この第２スイッチ２２の出力側に接続した第２スイッチ接続線２３が、他の無停電電源装置に設けている第２スイッチ２２の出力側に接続されている。よって第２スイッチ２２と第３スイッチ２４をオンにすれば、前述と同様に第２電流電圧変換器２７は並列運転中の無停電電源装置の１台当たりの平均電流を検出するから、第２電流電圧変換器２７の出力と第１電流電圧変換器１７の出力とを比較し、両者に差異があれば、いずれかの回路に異常ありと判定できる。すなわち電流指令値が正しいか否かを知ることができる。
【００１７】
第２スイッチ２２は、直送用開閉器４Ｂまたは出力用開閉器４Ｃの何れかがオンで、且つ保守用開閉器７がオンのときにオンする。また第３スイッチ２４は、無停電電源装置２が動作中（動作中とは出力用開閉器４Ｃをオンにすれば電力を供給できる状態）のときにオンとなる。従って、例えば各直送給電回路が電力供給中ならば、第２電流電圧変換器２７が検出する電流は、動作中の無停電電源装置の台数に対応した１台当たりの平均電流である。すなわち直送給電回路の３回路が運転中で、これを無停電電源装置へ切り換えたときに、運転できるのが２台の無停電電源装置であるならば、直送給電回路の３回路分の電流を２台の無停電電源装置で受け持つときの１台当たりの電流を検出する。よって無停電電源装置に故障機があるときに、過電流になるか否かを判断できる。
【００１８】
図２は本発明の第２実施例を表した回路図であって、平均電流を検出する回路であるが、この図２は２台の無停電電源装置の平均電流を検出する場合である。
この図２において、中央より左側が１号機で、右側が２号機であるとする。１号機のみが単独で運転しているときは、スイッチ３４はオンするがスイッチ３９はオフであるから、接続線３０には電流は流れない。このとき定電流源３１（図１の第１変流器１１に対応）の出力は、補助変変流器３２を介して信号変換器３３で表示される。
【００１９】
ここで２号機も運転するとスイッチ３９もオンするから、定電流源３１の出力と定電流源３６の出力に差異があっても、接続線３０にはこの差を解消する方向の電流が流れ、信号変換器３３と３８は、定電流源３１と定電流源３６の出力を平均した値を表示する。
図３は図１の電流検出部を複線で示して本発明の第３実施例を表した回路図であるが、各符号とその名称・用途・機能は、図１と同じであるから、これらの説明は省略しその動作の説明を行う。
【００２０】
無停電電源装置が運転中は第１スイッチ１２はオンであるが、他機と並列運転していなければ、第１スイッチ接続線１３は他機とつながらないから、第１電流電圧変換器１７は自機の出力電流が表示される。また他機と並列運転していれば、図２で既述の動作で平均電流が得られるから、この平均電流を自機の出力電流の目標値にして、自機の出力電流を制御する。更に直送給電回路で運転中ならば第１スイッチ１２はオフとなるから、自己の直送給電回路の電流が第１電流電圧変換器１７から得られる。
【００２１】
更に、無停電電源装置が運転中で他機と並列運転中ならば第２スイッチ２２と第３スイッチ２４が共にオンであるから、第２電流電圧変換器２７は並列運転中の無停電電源装置の平均電流を計測する。これのとき第１電流電圧変換器１７も平均電流を計測するから両者は同じ値であるが、もしも値が異なるときはなんらかの以上が発生して、電流指令値が正しくない恐れがあると判断できる。
【００２２】
また複数の直送給電回路が電力を送出中にスタンバイして、いつでも電力を送出できる状態にある無停電電源装置のみが第３スイッチ２４をオンにするから、例えば直送給電回路が３回路でそれぞれが100Aを出力している場合でも、スタンバイしている無停電電源装置が２台ならば、100A×３÷２＝150Aなる計算を行って、３回路の直送給電回路から２台の無停電電源装置に切り換わったときに、無停電電源装置の１台分の電流値を第２電流電圧変換器２７が表示する。よって直送給電回路から無停電電源装置へ切り換わったときに、無停電電源装置が過電流になる恐れの有無を、予め知ることができる。
【００２３】
【発明の効果】
直送切り換え回路バックアップ方式無停電電源装置の複数組を並列運転する場合に、本発明では無停電電源装置の電流目標値となる１台当たりの平均電流を別個の回路で算出するから、両者を比較することで電流指令値に異常があるか否かを判断できるという効果が得られる。また、直送給電回路の運転回路数よりもスタンバイしている無停電電源装置の台数が少ない場合は、直送給電回路から無停電電源装置へ切り換えた場合に無停電電源装置が過電流になる恐れがあるが、本発明では無停電電源装置の１台分が分担すべき電流を予め知ることができるように回路を構成しているので、無停電電源装置側へ切り換えた途端に無停電電源装置が過電流になって、再び直送給電回路へ切り換わってしまうような不具合を未然に防止できる効果も得られる。
【図面の簡単な説明】
【図１】本発明の第１実施例を表した回路図
【図２】本発明の第２実施例を表した回路図
【図３】図１の電流検出部を複線で示して本発明の第３実施例を表した回路図
【図４】直送切り換え回路バックアップ方式無停電電源装置の電流検出の従来例を示した回路図
【符号の説明】
１母線
２無停電電源装置
３直送給電回路
４無瞬断切り換え装置
４Ａ交流スイッチ
４Ｂ直送用開閉器
４Ｃ出力用開閉器
５出力変流器
６主変流器
７保守用開閉器
８制御装置
１１第１変流器
１２第１スイッチ
１３第１スイッチ接続線
１６第１補助変流器
１７第１電流電圧変換器
２１第２変流器
２２第２スイッチ
２３第２スイッチ接続線
２４第３スイッチ
２６第２補助変流器
２７第２電流電圧変換器
２８短絡ダイオード
３１出力補助変流器
３２第３電流電圧変換器
４１電流加算器
４２運転台数カウンタ
４３除算器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a device for detecting a current required when a direct feed power supply circuit or an uninterruptible power supply operates in parallel, and a method for detecting the current.
[0002]
[Prior art]
When a plurality of uninterruptible power supply devices are operated in parallel, it is well known that each uninterruptible power supply device must share its output current equally. For this purpose, a calculation circuit for the procedure of separately measuring the output currents of the uninterruptible power supply devices in parallel operation, summing them, and dividing the total value by the number of operating units is provided. In addition, if the number of uninterruptible power supply units changes due to a failure during parallel operation, the shared current of the uninterruptible power supply unit that continues to operate also changes. It is also necessary to be able to respond promptly. Furthermore, the average current value obtained in this way is used as a target value, and each uninterruptible power supply is controlled so that its output current matches the target value. Therefore, this average current value must be correct. .
[0003]
FIG. 4 is a circuit diagram showing a conventional example of current detection in a direct transmission switching circuit backup type uninterruptible power supply. As shown in the figure, the uninterruptible power supply 2 and the direct feed circuit 3 are connected in parallel via an uninterruptible switching device 4 and connected to the bus 1 via a maintenance switch 7. Although not shown in the figure, the bus 1 is connected in parallel by connecting a plurality of uninterruptible power supply devices having the same configuration.
[0004]
The uninterruptible switching device 4 is composed of an AC switch 4A, a direct switch 4B, and an output switch 4C. Normally, the AC switch 4A and the direct switch 4B are turned off and the output switch 4C is turned on. Thus, the uninterruptible power supply 2 supplies AC power to the bus 1 via the maintenance switch 7. At this time, the output of the uninterruptible power supply 2 and the output of the direct feed circuit 3 are in a synchronized state. Therefore, if the uninterruptible power supply 2 breaks down or becomes overcurrent, the AC switch 4A is immediately turned on, and the supply of AC power to the bus 1 is uninterrupted and generates a shock. It is possible to switch from the uninterruptible power supply 2 to the direct feed circuit 3 without any trouble. During the feeding of the direct power feeding circuit 3, the uninterruptible power supply 2 generates a voltage synchronized with the direct feeding power circuit 3 and is in a standby state, and the power switching from the direct feeding power circuit 3 to the uninterruptible power supply 2 is performed according to the switching command. Made without interruption.
[0005]
When a plurality of uninterruptible power supply devices 2 are operating in parallel, it is necessary to equalize the output current of each uninterruptible power supply device 2. Therefore, the current detected by the main current transformer 6 provided in the circuit of the maintenance switch 7 is input to the current adder 41 together with the current detected by the main current transformer 6 of the other uninterruptible power supply, and the sum of these currents. Calculate the current. On the other hand, by inputting the ON signal of the output switch 4C together with the ON signal of the output switch 4C of another uninterruptible power supply to the operating number counter 42, the number of uninterruptible power supplies in parallel operation is obtained. The divider 43 calculates the average current per unit by dividing the total current value by the number of operating units. The control device 8 uses the average current as a command value, and performs control to match the output current of the uninterruptible power supply 2 detected by the output current transformer 5 with the average current. Since each uninterruptible power supply unit in parallel operation performs control with this average current as a command value, all uninterruptible power supply units can be operated with the same output current.
[0006]
Although not shown in the figure, the total current when power is fed by the direct feed circuit 3 can be known by the current adder 41, and from the number of direct feed switches 4B turned on automatically or It is also possible to know the average current per circuit of the direct feed circuit manually.
[0007]
[Problems to be solved by the invention]
In the conventional circuit shown in FIG. 4, the divider 43 gives a current command value to each uninterruptible power supply unit during parallel operation of the uninterruptible power supply units, but each circuit that calculates the average current malfunctions and is correct. If the current command value cannot be obtained, there is a risk that all uninterruptible power supplies fall into an uncontrollable state, but nevertheless, there is a problem that it cannot be confirmed whether or not the calculated current command value is correct.
[0008]
For example, assuming that the output current per circuit of a direct power feeding circuit that is feeding power in parallel in three circuits is 100 A, and the current capacity per unit of an uninterruptible power supply in standby is 120 A, three circuits There is no problem when switching from a parallel direct power supply circuit to three parallel uninterruptible power supply units, but if there are only two uninterruptible power supply units on standby due to a failure, etc., one unit is 150A. Since the current is shared and the overcurrent occurs, a problem of returning to the power feeding from the direct feed power supply circuit occurs again. That is, in the conventional equipment, even if the average current per unit of uninterruptible power supply units in parallel operation can be calculated, the average current per circuit of the direct power feeding circuit or the uninterruptible power supply unit in the standby state can be calculated. There was a problem that the average current per unit that would be shared if operated in parallel could not be predicted.
[0009]
Accordingly an object of this invention is to allow the mutual check by calculating the average current as a current command value of the uninterruptible power supply in parallel operation to double the average current of the direct power supply circuit, Stan Ba Yi state It is to be able to calculate the average current when the uninterruptible power supply devices in the above are operated in parallel.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the parallel operation current detection device and the current detection method of the uninterruptible power supply according to the present invention include:
Connect the direct switch provided on the output side of the direct feed circuit and the output switch provided on the output side of the uninterruptible power supply, and provide a maintenance switch between this connection point and the bus. In the parallel operation device of the uninterruptible power supply configured by configuring the direct transfer switching circuit backup method uninterruptible power supply and connecting multiple sets of these to the bus,
An output current transformer for detecting the current of the circuit of the output switch, and a signal of a desired level connected to the secondary winding of the output current transformer directly or via an auxiliary current transformer A first signal converter for converting to a first current transformer, a first current transformer for detecting a current of the circuit of the maintenance switch, a second current transformer, and a secondary winding of the first current transformer; A first switch that is turned on when both the output switch and the maintenance switch are on and the uninterruptible power supply is in operation; the output side of the first switch; A first switch connection line connecting the output side of each first switch belonging to the power failure power supply, a first auxiliary current transformer connected to the secondary winding of the first current transformer via a resistor, A second signal converter connected to the secondary winding of the first auxiliary current transformer to convert the input signal into a signal of a desired level; A second switch that is connected to the secondary winding of the two current transformers and that is turned on when either the direct feed switch or the output switch is on and the maintenance switch is on; A second switch connection line connecting the output side of the second switch and the output side of each second switch belonging to each of the other uninterruptible power supplies, and connected to the secondary winding of the second current transformer A third switch that is turned on when the uninterruptible power supply is in operation, a second auxiliary current transformer that is connected to the output side of the third switch via a resistor, and the second auxiliary current transformer. A third signal converter connected to the secondary winding of the current transformer to convert the input signal into a signal of a desired level, and connected to the secondary winding of the second current transformer, A semiconductor element that conducts when the voltage of the wire exceeds a predetermined value and short-circuits the secondary winding.
[0012]
The average output current signal per uninterruptible power supply unit in parallel operation to be compared with the output signal of the second signal converter is the direct feed power supply circuit of the direct feed switching circuit backup type uninterruptible power supply unit and the uninterruptible power supply unit. A second current transformer is installed in the circuit combined with the output circuit, and the secondary windings of each second current transformer belonging to each uninterruptible power supply unit in parallel operation are connected by the second switch connection line. In addition, a second auxiliary current transformer is connected to each of the secondary windings of the second current transformer belonging to each uninterruptible power supply unit in parallel operation through a resistor, and the second auxiliary current transformer Detection is from a third signal converter connected separately to each of the secondary windings.
[0013]
The average output current signal per unit of uninterruptible power supply units that should be operated in parallel when switching from the direct feed circuit to the uninterruptible power supply unit is the same as that of the direct feed circuit of the direct transfer switching circuit backup type uninterruptible power supply unit. A second current transformer is installed in a circuit that is coupled with the output circuit of the power failure power supply, and the secondary windings of each second current transformer belonging to each of the direct power feeding circuits in parallel operation are connected to the second switch. A second auxiliary current transformer is connected to each of the secondary windings of the second current transformer belonging to each uninterruptible power supply in operation via a resistor, and the second auxiliary current transformer From a third signal converter connected separately to each of the secondary windings.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a circuit diagram showing a first embodiment of the present invention. The main circuit portion described in the circuit of the first embodiment is a bus 1, an uninterruptible power supply 2, a direct feed circuit 3, and The names, applications, and functions of the instantaneous interruption switching device 4, the output current transformer 5, the main current transformer 6, and the maintenance switch 7 are the same as those of the conventional circuit described above with reference to FIG. Is omitted.
[0015]
In the circuit of the first embodiment, the first current transformer 11 and the second current transformer 21 are installed in the secondary winding of the main current transformer 6, but the first current transformer 11 and the second current transformer 21 are provided. It is the same even if a current transformer of the same type as the main current transformer 6 is inserted in the circuit of the maintenance switch 7 instead of the current transformer 21. A first auxiliary current transformer 16 is installed in the secondary winding of the first current transformer 11 via a resistor 15. The secondary winding of the first auxiliary current transformer 16 is provided as a signal converter. The first current-voltage converter 17 is connected. Further, a first switch 12 is provided in the secondary winding of the first current transformer 11, and a first switch connection line 13 connected to the output side of the first switch 12 is provided in another uninterruptible power supply. It is connected to the output side of the first switch 12. Here, the first switch 12 is turned on when the output switch 4C and the maintenance switch 7 are on and the uninterruptible power supply 2 is operating. When the first switch 12 is turned on, an average value per unit of the output current of the uninterruptible power supply unit in parallel operation appears in the first current-voltage converter 17. Further, when the third current-voltage converter 32 is connected to the secondary winding of the output auxiliary current transformer 31 provided in the secondary winding of the output switch 4C, the output current of the uninterruptible power supply 2 can be detected. Therefore, in the control device 8, the output of the first auxiliary current transformer 16 (average current of the uninterruptible power supply device) is used as a command value, and the output current of the uninterruptible power supply 2 that is the output of the third current-voltage converter 32 is calculated. Control to match the command value can be performed.
[0016]
If the first switch 12 is turned off, the circuit current of the maintenance switch 7 can be detected.
In the secondary winding of the second current transformer 21 provided in the secondary winding of the main current transformer 6, a second auxiliary current transformer 26 is installed via a third switch 24 and a resistor 25. A second current-voltage converter 27 as a signal converter is connected to the secondary winding of the second auxiliary current transformer 26. Further, the secondary winding of the second current transformer 21 is provided with a second switch 22, and a second switch connection line 23 connected to the output side of the second switch 22 is provided in another uninterruptible power supply. It is connected to the output side of the second switch 22. Therefore, if the second switch 22 and the third switch 24 are turned on, the second current-voltage converter 27 detects the average current per unit of uninterruptible power supply units in parallel operation as described above. If the output of the current-voltage converter 27 and the output of the first current-voltage converter 17 are compared and there is a difference between them, it can be determined that there is an abnormality in any of the circuits. That is, it can be known whether or not the current command value is correct.
[0017]
The second switch 22 is turned on when either the direct switch 4B or the output switch 4C is on and the maintenance switch 7 is on. Further, the third switch 24 is turned on when the uninterruptible power supply 2 is in operation (in operation, a state where power can be supplied by turning on the output switch 4C). Therefore, for example, if each direct feed power supply circuit is supplying power, the current detected by the second current-voltage converter 27 is an average current per unit corresponding to the number of uninterruptible power supply units in operation. That is, if three circuits of the direct power feeding circuit are in operation and are switched to the uninterruptible power supply, if two uninterruptible power supplies can be operated, the current for the three circuits of the direct power feeding circuit is The current per unit when it is handled by two uninterruptible power supplies is detected. Therefore, it can be determined whether or not there is an overcurrent when the uninterruptible power supply has a fault device.
[0018]
FIG. 2 is a circuit diagram showing a second embodiment of the present invention, which is a circuit for detecting an average current. FIG. 2 shows a case in which the average current of two uninterruptible power supplies is detected.
In FIG. 2, it is assumed that the left side from the center is Unit 1 and the right side is Unit 2. When only Unit 1 is operating alone, the switch 34 is turned on but the switch 39 is turned off, so that no current flows through the connection line 30. At this time, the output of the constant current source 31 (corresponding to the first current transformer 11 in FIG. 1) is displayed by the signal converter 33 via the auxiliary current transformer 32.
[0019]
Here, when Unit 2 is also operated, the switch 39 is also turned on. Therefore, even if there is a difference between the output of the constant current source 31 and the output of the constant current source 36, a current in a direction to eliminate this difference flows through the connection line 30. The signal converters 33 and 38 display values obtained by averaging the outputs of the constant current source 31 and the constant current source 36.
FIG. 3 is a circuit diagram showing the third embodiment of the present invention by showing the current detection unit of FIG. 1 with double lines, but since the reference numerals, names, uses, and functions are the same as those in FIG. The explanation of the operation will be omitted.
[0020]
During operation the uninterruptible power supply has a first switch 12 is turned on, if not parallel OPERATION other machines, since the first switch connecting line 13 is not connected to other apparatus, the first current-voltage converter 17 The output current of your machine is displayed. If the operation is performed in parallel with another machine, the average current can be obtained by the operation described above with reference to FIG. 2. Therefore, the output current of the own machine is controlled by setting the average current as a target value of the output current of the own machine. Furthermore, since the first switch 12 is turned off when the direct feed power supply circuit is operating, the current of the direct feed power supply circuit can be obtained from the first current-voltage converter 17.
[0021]
Furthermore, since the second switch 22 and the third switch 24 are both on when the uninterruptible power supply is in operation and in parallel operation with other units, the second current-voltage converter 27 is connected to the uninterruptible power supply in parallel operation. Measure the average current. At this time, since the first current-voltage converter 17 also measures the average current, both are the same value. However, if the values are different, it can be determined that there is a risk that the current command value may be incorrect if some value occurs. .
[0022]
In addition, since only the uninterruptible power supply that is in a state where a plurality of direct power feeding circuits are in a power standby state and can send power at any time turns on the third switch 24, for example, each of the three direct power feeding circuits includes three circuits. Even if 100A is output, if there are two uninterruptible power supplies in standby, calculate 100A x 3/2 = 150A and calculate 2 uninterruptible power supplies from 3 direct feed circuits. When switching to, the second current-voltage converter 27 displays the current value for one uninterruptible power supply. Therefore, it is possible to know in advance whether or not the uninterruptible power supply may become overcurrent when the direct power supply circuit is switched to the uninterruptible power supply.
[0023]
【The invention's effect】
When multiple sets of direct transmission switching circuit backup type uninterruptible power supply units are operated in parallel, the present invention calculates the average current per unit, which is the current target value of the uninterruptible power supply unit, in a separate circuit. effect that can determine whether there is an abnormality in the current command value by. In addition, if the number of uninterruptible power supply units that are in standby is smaller than the number of operating circuits of the direct power supply circuit, the uninterruptible power supply unit may become overcurrent when switching from the direct power supply circuit to the uninterruptible power supply unit. the case, since one minute of uninterruptible power supply in the present invention is a circuit to be able to know in advance the current to be shared, the uninterruptible power supply as soon as switched to the uninterruptible power supply side It is also possible to prevent an inconvenience such that the overcurrent is switched to the direct feed circuit again.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a first embodiment of the present invention. FIG. 2 is a circuit diagram showing a second embodiment of the present invention. FIG. 3 shows the current detection unit of FIG. Circuit diagram showing the third embodiment [FIG. 4] Circuit diagram showing a conventional example of current detection of the direct-switching circuit backup type uninterruptible power supply [description of symbols]
1 Busbar 2 Uninterruptible Power Supply 3 Direct Power Supply Circuit 4 Uninterruptible Switching Device 4A AC Switch 4B Direct Switch 4C Output Switch 5 Output Current Transformer 6 Main Current Transformer 7 Maintenance Switch 8 Controller 11 1 current transformer 12 first switch 13 first switch connection line 16 first auxiliary current transformer 17 first current voltage converter 21 second current transformer 22 second switch 23 second switch connection line 24 third switch 26 second 2 Auxiliary current transformer 27 Second current-voltage converter 28 Short-circuit diode 31 Output auxiliary current transformer 32 Third current-voltage converter 41 Current adder 42 Number of operating counters 43 Divider

Claims

Connect the direct switch provided on the output side of the direct feed circuit and the output switch provided on the output side of the uninterruptible power supply, and provide a maintenance switch between this connection point and the bus. In the parallel operation device of the uninterruptible power supply configured by configuring the direct transfer switching circuit backup method uninterruptible power supply and connecting multiple sets of these to the bus,
An output current transformer for detecting a current of a circuit of the output switch;
A first signal converter connected to the secondary winding of the output current transformer directly or via an auxiliary current transformer to convert the input signal to a signal of a desired level;
A first current transformer and a second current transformer for detecting a current in a circuit of the maintenance switch;
A first switch connected to the secondary winding of the first current transformer and turned on when both the output switch and the maintenance switch are on and the uninterruptible power supply is in operation. When,
A first switch connection line connecting the output side of the first switch and the output side of each first switch belonging to each other uninterruptible power supply;
A first auxiliary current transformer connected via a resistor to the secondary winding of the first current transformer;
A second signal converter connected to the secondary winding of the first auxiliary current transformer to convert the input signal to a signal of a desired level;
A second switch connected to the secondary winding of the second current transformer and turned on when either the direct-feed switch or the output switch is on and the maintenance switch is on When,
A second switch connection line connecting the output side of the second switch and the output side of each second switch belonging to each of the other uninterruptible power supply devices;
A third switch connected to the secondary winding of the second current transformer and turned on when the uninterruptible power supply is in operation;
A second auxiliary current transformer connected to the output side of the third switch via a resistor;
A third signal converter connected to the secondary winding of the second auxiliary current transformer to convert the input signal into a signal of a desired level;
A semiconductor element connected to the secondary winding of the second current transformer and conducting when the voltage of the secondary winding exceeds a predetermined value to short-circuit the secondary winding;
A parallel operation current detecting device for an uninterruptible power supply, comprising:

In the parallel operation current detection device of the uninterruptible power supply according to claim 1,
The first current transformer and the second current transformer that detect a current of the maintenance switch circuit are connected to a secondary winding of a main current transformer provided in the maintenance switch circuit. An uninterruptible power supply parallel operating current detector.

The first current transformer and the second current transformer are installed in a circuit that combines the direct feed power supply circuit of the direct feed switching circuit backup method uninterruptible power supply and the output circuit of the uninterruptible power supply,
The secondary windings of the respective first current transformers belonging to the respective uninterruptible power supply units in parallel operation are connected to each other by the first switch connection line, and the secondary windings of the respective first current transformers are connected to each other. Connect the first auxiliary current transformer through a resistor,
An average output current signal serving as a current target value per uninterruptible power supply unit in parallel operation is detected from a second signal converter separately connected to each secondary winding of the first auxiliary current transformer. ,
The secondary windings of the respective second current transformers belonging to the respective uninterruptible power supply units in parallel operation are connected to each other by the second switch connection line, and the second belonging to each uninterruptible power supply unit in parallel operation. A second auxiliary current transformer is connected to each of the secondary windings of the current transformer through a resistor;
Per uninterruptible power supply unit in parallel operation to be compared with the output signal of the second signal converter from a third signal converter separately connected to each of the secondary windings of the second auxiliary current transformer An average output current signal of the uninterruptible power supply is detected.

The second current transformer is installed in the circuit that combines the direct power feeding circuit of the direct transmission switching circuit backup method uninterruptible power supply and the output circuit of the uninterruptible power supply,
The secondary windings of the second current transformers belonging to the respective direct power feeding circuits in parallel operation are connected to each other by the second switch connection line, and the second current transformers belonging to the uninterruptible power supply units in operation A second auxiliary current transformer is connected to each of the secondary windings of the
The number of uninterruptible power supplies to be operated in parallel when the third signal converter connected to each of the secondary windings of the second auxiliary current transformer is switched from the direct feed circuit to the uninterruptible power supply. A parallel operation current detection method for an uninterruptible power supply, wherein an average output current signal per device is detected.