JP2004180415A

JP2004180415A - Current limiter

Info

Publication number: JP2004180415A
Application number: JP2002343217A
Authority: JP
Inventors: Junji Kondo; 潤次近藤; Itaru Ishii; 格石井
Original assignee: National Institute of Advanced Industrial Science and Technology AIST
Current assignee: National Institute of Advanced Industrial Science and Technology AIST
Priority date: 2002-11-27
Filing date: 2002-11-27
Publication date: 2004-06-24
Anticipated expiration: 2022-11-27
Also published as: JP3777424B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current limiter for suppression of a fault current which is easily applicable as a transformer provided with a current limiting function. <P>SOLUTION: A first projection 11a and a second projection 11b are made in a fixed iron core 11 which can form a closed magnetic path passing through a primary winding 1 and a secondary winding 2, and a bar-shaped movable structure 15 which is provided by connecting a movable iron piece consisting of ferromagnetic material and a supporting material consisting of nonmagnetic material is arranged slidably between the first projection 11a and the second projection 11b, and at normal current application, the supporting material is positioned between the first projection 11a and the second projection 11b not to form a leakage magnetic path, and at current limitation, the movable iron piece is positioned between the first projection 11a and the second projection 11b to form a leakage magnetic path thereby reducing the magnetic coupling between the primary winding 1 and the secondary winding 2 so as to suppress a fault current. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、系統の事故時の過電流を抑制する限流器に関する。
【０００２】
【従来の技術】
これまで、アーク・抵抗を利用した方式、自己消去能力のあるＧＴＯのような半導体素子を利用した方式、ダイオードブリッジと直流リアクトルを用いた方式、超電導の常電導転移現象を利用した方式、ＬＣ共振を利用した方式等、種々の限流器が提案・開発されている。
【０００３】
【特許文献１】
特開２０００−１３９９３号公報
【特許文献２】
特開２００２−２６２４５０号公報
【０００４】
【発明が解決しようとする課題】
しかしながら、限流器が限流動作を行う際、その限流能力が高いほど限流器の両端子間には高い電圧が印加されるため、電流を零にできる方式の場合は、その両端電圧は線路電圧と等しくなり、この高電圧に耐える限流器は大容量にする必要があり、寸法が大きく、高価になってしまう。また、これを送配電設備として別途設置するには、それを設置する空間を確保しなければならず、設置箇所が制限されるという問題もある。
【０００５】
さらに、超電導の常電導転移現象を利用した方式は、常電導転移後に再び超電導導体に復帰するのに時間がかかる上、その復帰時間を制御するのが難しいという問題がある。その上、クライオスタットの設置を要するなど、設備としても規模が大きくなってしまう。
【０００６】
また、電力系統では、各線路の送電容量に応じて適した電圧階級があり、電力エネルギーの発生から消費の流れの中で、変圧器により数回変圧されるため、線路中に複数台の変圧器が必須であるが、これらの変圧器に対して、上記のような従来の限流装置を設けることは困難である。
【０００７】
そして、現状の送電系統では事故時過電流を遮断器の定格遮断電流以下に抑えつつ、系統の安定度を確保しているが、今後の系統規模の拡大に伴い、系統の連系点などでは事故時過電流が定格遮断電流を上回る状況が考えられる。また、配電系統においては、今後の電気事業自由化の進展に伴い連系される分散電源が増加していくと予想されるが、ある容量以上の回転機系の分散電源が連系された場合、故障電流が配電用遮断器の遮断容量を上回ることが危惧されている。
【０００８】
そこで、本発明は、簡単で経済的な故障電流抑制用の限流器であって、変圧器への応用も簡単な限流器の提供を目的とする。
【０００９】
【課題を解決するための手段】
上記の課題を解決するために、本発明は、給電系統に接続された一次巻線と送電系統に接続された二次巻線を経由する閉じた閉磁路を形成し得る任意形状のヨークと、上記一次巻線と上記二次巻線の間に漏れ磁路を生ぜしめるように、上記ヨークの２点間を磁気的に結合させる任意形状の磁性材料よりなる磁路形成部を備えた可動体と、上記可動体の磁路形成部によって漏れ磁路が形成されない第１位置と、上記可動体の磁路形成部によって漏れ磁路が形成され得る第２位置とに、上記可動体を移動させる可動体移動手段と、予め定めた限流機能作動条件が達成されたことを検出する限流機能作動条件検出手段と、を備え、上記限流機能作動条件検出手段が限流機能作動条件の達成を検出することに基づいて、上記可動体移動手段が可動体を第１位置から第２位置に移動させるようにしたことを特徴とする。
【００１０】
【発明の実施の形態】
次に、添付図面に基づいて、本発明に係る限流器の実施形態を説明する。
【００１１】
図１は、本発明に係る限流器の一実施形態を示す構造図である。図中、１は一次巻線、２は二次巻線、１１は固定鉄心で、上記一次巻線１と二次巻線２を経由する閉じた閉磁路を形成し得る任意形状のヨークとして機能する。
【００１２】
可動体１５の詳細は、図２に示すように、可動鉄片１２と支持材１３からなる棒状体である。可動鉄片１２は、一次巻線１と二次巻線２との間に漏れ磁路を生ぜしめるように、固定鉄心１１の２点間を磁気的に結合させる任意形状の磁性材料よりなる磁路形成部として機能する。なお、この可動鉄片１２と上記固定鉄心１１とは強磁性材料である電磁鋼板を積層して形成される。また、支持材１３は非磁性材料よりなる。
【００１３】
上記のように構成した可動体１５は、固定鉄心１１に設けた第１突部１１ａと第２突部１１ｂとの間に可動鉄片１２が位置する状態と、第１突部１１ａと第２突部１１ｂとの間に支持材１３が位置する状態とに変換可能な方向（図２中における矢印１４の方向）にスライド移動可能である。
【００１４】
上記のように構成された限流器は、一次巻線１と二次巻線２を同じ巻線比にすれば、送配電系統の適所に挿入して使える限流器として機能するが、一次巻線１と二次巻線２の巻線比を変えて構成すれば、限流機能付き変圧器として利用できる。図３および図４は、変圧器として使用した例を示すもので、限流機能が作動していない通常通電状態（固定鉄心１１に設けた第１突部１１ａと第２突部１１ｂとの間に支持材１３が位置する状態）を示した図である。また、図４は、限流機能が作動した限流状態（固定鉄心１１に設けた第１突部１１ａと第２突部１１ｂとの間に可動鉄片１２が位置する状態）を示した図である。なお、図３と図４において、２１は交流電源、２２は負荷である。
【００１５】
図５と図６は、図１の限流器を横から見た側面図であり、図５は通常通電状態（固定鉄心１１に設けた第１突部１１ａと第２突部１１ｂとの間に支持材１３が位置する状態）を示し、図６は限流状態（固定鉄心１１に設けた第１突部１１ａと第２突部１１ｂとの間に可動鉄片１２が位置する状態）を示した図である。
【００１６】
また、図５と図６には、予め定めた限流機能作動条件が達成されたことを検出する限流機能作動条件検出手段として機能する過電流検出器３１や、可動体１５を移動させる可動体移動手段としての駆動機構（例えば、電磁リレー３２、励磁電源３３、電磁石ソレノイド３４、引張ばね３５等より構成）も示してある。
【００１７】
通常通電時には、電磁リレー３２をオンさせる。これにより、励磁電源３３より給電された電磁石ソレノイド３４は励磁され、発生する電磁力が引張ばね３５の縮もうとする力に抗して可動体１５を図５の位置（可動体１５の支持材１３が第１突部１１ａと第２突部１１ｂとの間に来る位置）まで引っ張り、静止させるので、通常通電時においては、可動鉄片１２によって漏れ磁路が形成されない第１位置に可動体１５が移動されることとなる。
【００１８】
上記のように可動体１５が第１位置にあるとき、第１突部１１ａと第２突部１１ｂとの間には非磁性材料よりなる支持材１３があるため、この間の磁気抵抗が大きくなって、第１突部１１ａと第２突部１１ｂとの間の磁束φ_ｇはφ_１やφ_２と比べると小さくなり、第１突部１１ａと第２突部１１ｂとを経る磁路は形成されないものと看做せることから、通常通電時には漏れ磁路が形成されないのである。また、この通常通電時における限流器は、φ_ｇが充分に小さく、φ_１≒φ_２であれば、漏れリアクタンスが小さく電圧変動率の小さい通常のトランスとして機能する。
【００１９】
なお、強磁性体の比透磁率を無限大、非磁性材の比透磁率を１と近似し、鉄心の断面積をＳ、真空の透磁率をμ_０とすると、この磁気抵抗Ｒ_ｎは、第１突部１１ａと第２突部１１ｂとの間のギャップ長ｇを用いて、「Ｒ_ｎ＝ｇ／μ_０Ｓ」と表せる。一次巻線の巻数をｎ_１とすると、一次側から見た漏れリアクタンスＬ_ｎは「Ｌ_ｎ＝ｎ_１ ^２／Ｒ_ｎ」となる。
【００２０】
また、漏れリアクタンスをさらに小さくしたい場合は、非磁性支持材１３に銅やアルミニウムといった良導体を用い、その中を流れる渦電流でφ_ｇを打ち消す方法や、回路に直列にコンデンサを挿入して漏れリアクタンス分を補償する方法、あるいは、巻線に負荷時タップ切換機構を設けて、電圧変動分を補償する方法もある。
【００２１】
続いて、図４のように二次側で短絡または地絡事故が生じ、線路電流Ｉ_１またはＩ_２が限流開始電流値を超えた場合（限流機能作動条件が達成された場合）、これを限流機能作動条件検出手段としての過電流検出器３１で検出し、該過電流検出器３１の検出出力により電磁リレー３２をオフさせる。これにより、電磁石ソレノイド３４は消磁され、引張ばね３５の縮もうとする力により、可動体１５は速やかに図６の位置に移動するので、第１突部１１ａと可動鉄片１２と第２突部１１ｂを経る磁路（漏れ磁路）が形成される。すなわち、限流機能作動時においては、可動鉄片１２によって漏れ磁路が形成され得る第２位置に可動体１５が移動されることとなる。
【００２２】
この時、固定鉄心１１における第１突部１１ａと第２突部１１ｂと可動鉄片１２の接する面に僅かなギャップが生じる（可動体１５の移動に伴う摺動抵抗を発生させないため、僅かなギャップが必要となる）ものの、この僅かなギャップの長さをｐとすると、限流時の可動体１５を通る磁路の磁気抵抗Ｒ_ｆは、Ｒ_ｆ＝ｐ／μ_０Ｓと表すことができ、ｐ≪ｇであることからＲ_ｆ≪Ｒ_ｎとなる。
【００２３】
上記のようにして漏れ磁路を形成した時、一次側から見た漏れリアクタンスＬ_ｆはＬ_ｆ＝ｎ_１ ^２／Ｒ_ｆとなる。二次側事故時は、二次巻線の両端電圧がほぼ零のため、φ_２≒０となり、φ_１≒φ_ｇとなる。このとき一次電流Ｉ_１は、一次電圧をＶ_１、その角周波数をωとすると、Ｉ_１＝Ｖ_１／（ωＬ_ｆ）となる。ｐを小さくしＲ_ｆが小さくなれば、Ｌ_ｆが大きくなりＩ_１を抑制できる。すなわち、二次側で事故が生じた際に、可動体１５を移動させることで、故障電流を限流できる。
【００２４】
事故が解消され、送電を再開する際は、再び電磁リレー３２をオンにして電磁石ソレノイド３４を励磁すれば、発生した電磁力により可動体１５を図５の位置まで引っ張る。斯くして、再び変圧器の漏れリアクタンスは小さくなり、送電が開始される。
【００２５】
図７は、可動鉄片の移動により限流できることを実証する装置を作製し、試験を行った時の波形図である。一次巻線と二次巻線の巻線比は２：１で、二次巻線を短絡し、時刻０秒で電磁石ソレノイドの電流Ｉ_ｓｏｌを遮断した。図７を見て分かるように、電磁石ソレノイドの電流Ｉ_ｓｏｌを遮断して３サイクル半から４サイクル分の時間を経た後に、可動鉄片の移動が完了し、一次電流Ｉ_１と二次電流Ｉ_２が限流された。
【００２６】
なお、図７より分かるように、本実施形態に係る限流器を適用した変圧器で限流機能が作動した後も、二次側の電流を完全に遮断することはできないが、危険回避には十分なレベルに抑制することが可能である。しかも、可動部分に高電圧およびアークが発生しないので、電極の消耗を抑制できるという利点もある。
【００２７】
また、事故の検出から限流動作が完了するまでの時間（実質的には、電磁石ソレノイド３４の電流Ｉ_ｓｏｌを遮断してから一次電流Ｉ_１と二次電流Ｉ_２が限流されるまでの時間）を更に短くするには、引張ばね３５をさらに縮む力の強いものに変えるなど、駆動機構の改良を行えば良い。無論、電磁石ソレノイドと引張バネではない他の可動体駆動機構を採用して、より高速な可動体移動を実現するようにしても良い。なお、可動体移動手段としてどのような機構を採用するかは、任意設計事項の範囲であり、より移動速度が速く小型・軽量・安価なものが望ましい。
【００２８】
また、上記実施形態においては、固定鉄心１１に第１突部１１ａと第２突部１１ｂとを設けて、この間に一つの可動体を位置させることで漏れ磁路を形成するものとしたが、漏れ磁路の形成手法も、これに限定されるものではなく、可動体の磁路形成部が第２位置にある限流作動時における漏れ磁路の磁気抵抗が低く、可動体の磁路形成部が第１位置にある通常通電時における漏れ磁路形成部位間の磁気抵抗が高くなるようにできれば良い。
【００２９】
【発明の効果】
以上説明したように、請求項１に係る限流器によれば、限流機能作動条件が達成されたことを限流機能作動条件検出手段が検出すると、可動体移動手段が可動体を第１位置から第２位置に移動させることで、漏れ磁路が形成され得る状態となり、第１巻線と第２巻線との磁気結合が切り換えられ、短絡等による故障電流を速やかに抑制することができる。しかも、超電導材の常電導転移現象を利用しないので、限流開始電流値や、通常通電状態への復帰時間が制御し易いという利点もある。
【００３０】
また、請求項１に係る限流器は、第１巻線と第２巻線との巻線比を変えることで、限流機能付き変圧器としても利用できる。その場合、可動体移動手段を設ける必要から、普通の変圧器に比べると、寸法が大きく、高価になるが、大容量限流器を変圧器とは別途に設ける場合に比べれば、設置に要する空間を小さくできるし、安価に提供できる。しかも、変圧器の巻線は元々その線路電圧に耐えるよう設計されているので、既存の変圧器に本発明を適用する場合は、その巻線を使用できるという利点もある。
【図面の簡単な説明】
【図１】本発明に係る限流器の一実施形態を示す概略構造図である。
【図２】図１における可動体の外観を示す斜視図である。
【図３】限流器を変圧器に適用した例であり、通常通電状態を表した説明図である。
【図４】限流器を変圧器に適用した例であり、限流状態を表した説明図である。
【図５】通常通電状態にある限流器の側面図である。
【図６】限流状態にある限流器の側面図である。
【図７】限流動作の実証試験における、一次電圧Ｖ_１、二次電圧Ｖ_２、一次電流Ｉ_１、二次電流Ｉ_２、電磁石ソレノイドの電流Ｉ_ｓｏｌの波形を表す図である。
【符号の説明】
１一次巻線
２二次巻線
１１固定鉄心
１２可動鉄片
１３非磁性支持材
１４可動体の可動方向を示す矢印
１５可動体
２１交流電源
２２負荷
３１過電流検出器
３２電磁リレー
３３励磁電源
３４電磁石ソレノイド
３５引張ばね[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a current limiter for suppressing an overcurrent at the time of a system failure.
[0002]
[Prior art]
Up to now, a method using an arc / resistance, a method using a semiconductor element such as GTO with self-erasing ability, a method using a diode bridge and a DC reactor, a method using a normal conduction transition phenomenon of superconductivity, LC resonance Various current limiters, such as a method using a current limiter, have been proposed and developed.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-13939 [Patent Document 2]
JP-A-2002-262450
[Problems to be solved by the invention]
However, when the current limiting device performs the current limiting operation, the higher the current limiting capability, the higher the voltage applied between both terminals of the current limiting device. Is equal to the line voltage, and the current limiter that can withstand this high voltage needs to have a large capacity, and is large in size and expensive. Further, in order to separately install the power transmission and distribution equipment, a space for installing the power transmission and distribution equipment must be secured, and there is a problem that the installation location is limited.
[0005]
Further, the method using the superconducting transition phenomenon of superconductivity has a problem that it takes time to return to the superconducting conductor again after the normal conducting transition, and it is difficult to control the return time. In addition, a cryostat needs to be installed, and the scale of the equipment becomes large.
[0006]
In addition, in the power system, there is a voltage class suitable for the transmission capacity of each line, and in the flow of consumption from the generation of power energy, the transformer is transformed several times by a transformer. Although a transformer is indispensable, it is difficult to provide a conventional current limiting device as described above for these transformers.
[0007]
In the current transmission system, the overcurrent at the time of the accident is kept below the rated breaking current of the circuit breaker and the stability of the system is ensured. It is possible that the overcurrent at the time of the accident exceeds the rated breaking current. In the distribution system, it is expected that the number of distributed power sources connected to each other will increase with the progress of liberalization of the electric power business. It is feared that the fault current exceeds the breaking capacity of the distribution circuit breaker.
[0008]
Therefore, an object of the present invention is to provide a simple and economical current limiter for suppressing a fault current, which can be easily applied to a transformer.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a yoke of any shape capable of forming a closed magnetic flux path via a primary winding connected to a power supply system and a secondary winding connected to a power transmission system, A movable body having a magnetic path forming portion made of a magnetic material of an arbitrary shape for magnetically coupling between two points of the yoke so as to generate a leakage magnetic path between the primary winding and the secondary winding. And moving the movable body to a first position where a leakage magnetic path is not formed by the magnetic path forming portion of the movable body and a second position where a leakage magnetic path can be formed by the magnetic path forming portion of the movable body. A moving body moving means, and a current limiting function operating condition detecting means for detecting that a predetermined current limiting function operating condition is achieved, wherein the current limiting function operating condition detecting means achieves the current limiting function operating condition. The movable body moving means moves the movable body based on detecting Characterized in that from the first position to be moved to the second position.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of a current limiter according to the present invention will be described with reference to the accompanying drawings.
[0011]
FIG. 1 is a structural diagram showing one embodiment of a current limiter according to the present invention. In the drawing, 1 is a primary winding, 2 is a secondary winding, and 11 is a fixed iron core, which functions as a yoke of an arbitrary shape capable of forming a closed magnetic path passing through the primary winding 1 and the secondary winding 2. I do.
[0012]
The details of the movable body 15 are, as shown in FIG. 2, a rod-shaped body composed of a movable iron piece 12 and a support member 13. The movable iron piece 12 is a magnetic path made of a magnetic material of an arbitrary shape that magnetically couples two points of the fixed iron core 11 so as to generate a leakage magnetic path between the primary winding 1 and the secondary winding 2. Functions as a forming unit. Note that the movable iron piece 12 and the fixed iron core 11 are formed by laminating electromagnetic steel sheets, which are ferromagnetic materials. The support 13 is made of a non-magnetic material.
[0013]
The movable body 15 configured as described above has a state in which the movable iron piece 12 is located between the first protrusion 11a and the second protrusion 11b provided on the fixed iron core 11, a state in which the first protrusion 11a and the second protrusion It is slidable in a direction (direction of arrow 14 in FIG. 2) that can be converted to a state in which the support member 13 is located between the support 11 and the portion 11b.
[0014]
If the primary winding 1 and the secondary winding 2 have the same turns ratio, the current limiting device configured as described above functions as a current limiting device that can be inserted into an appropriate place in the power transmission and distribution system. If the winding ratio of the winding 1 and the secondary winding 2 is changed, it can be used as a transformer with a current limiting function. FIGS. 3 and 4 show an example in which the transformer is used as a transformer, in a normal energized state in which the current limiting function is not activated (between the first protrusion 11a and the second protrusion 11b provided on the fixed iron core 11). (A state in which a support member 13 is located at a position shown in FIG. 2). FIG. 4 is a diagram showing a current limiting state in which the current limiting function is activated (a state in which the movable iron piece 12 is located between the first protrusion 11a and the second protrusion 11b provided on the fixed iron core 11). is there. 3 and 4, reference numeral 21 denotes an AC power supply, and reference numeral 22 denotes a load.
[0015]
5 and 6 are side views of the current limiter of FIG. 1 as viewed from the side, and FIG. 5 shows a normal energized state (between the first protrusion 11a and the second protrusion 11b provided on the fixed iron core 11). 6 shows a current limiting state (a state in which the movable iron piece 12 is located between the first projection 11a and the second projection 11b provided on the fixed iron core 11). FIG.
[0016]
FIGS. 5 and 6 show an overcurrent detector 31 functioning as a current limiting function operating condition detecting means for detecting that a predetermined current limiting function operating condition has been achieved, and a movable device for moving the movable body 15. A drive mechanism (for example, configured by an electromagnetic relay 32, an excitation power supply 33, an electromagnet solenoid 34, a tension spring 35, and the like) as a body moving unit is also illustrated.
[0017]
During normal energization, the electromagnetic relay 32 is turned on. As a result, the electromagnet solenoid 34 supplied from the excitation power supply 33 is excited, and the generated electromagnetic force resists the force of the tension spring 35 to shrink, and moves the movable body 15 to the position shown in FIG. 13 is located between the first protrusion 11a and the second protrusion 11b) and is stopped, so that the movable body 15 is at the first position where no leakage magnetic path is formed by the movable iron piece 12 during normal energization. Will be moved.
[0018]
When the movable body 15 is at the first position as described above, the support 13 made of a non-magnetic material is provided between the first protrusion 11a and the second protrusion 11b, so that the magnetic resistance therebetween becomes large. Te, the magnetic flux phi _g between the first projection 11a and the second protrusion 11b decreases when compared to phi ₁ and phi _2, the magnetic path passing through the first projection 11a and the second projection 11b is formed Therefore, no leakage magnetic path is formed during normal energization. Further, the current limiter at the time of the normal energization functions as a normal transformer having a small leakage reactance and a small voltage fluctuation rate if φ _g is sufficiently small and φ ₁ ≒ φ ₂ .
[0019]
Incidentally, infinity relative permeability of the ferromagnetic material, the relative permeability of non-magnetic material is approximated to 1, the cross-sectional area of the core S, the magnetic permeability of vacuum and mu _0, the magnetic resistance R _n is Using the gap length g between the first protrusion 11a and the second protrusion 11b, it can be expressed as “R _n = g / μ ₀ S”. When the number of turns of the primary winding and _{n 1,} the leakage reactance _{L n} as seen from the primary side becomes _{_{^{_{"L n = n 1 2 / R}}}} n ".
[0020]
To further reduce the leakage reactance, a good conductor such as copper or aluminum is used for the non-magnetic support member 13 to cancel φ _g by an eddy current flowing in the non-magnetic support member, or a leakage reactance is inserted by inserting a capacitor in series with the circuit. There is also a method of compensating for the voltage fluctuation, or a method of providing a load tap change mechanism in the winding to compensate for the voltage fluctuation.
[0021]
Subsequently, (if it is achieved limiting function operating conditions) short or ground fault on the secondary side as shown in FIG. 4 occurs, line current I ₁ or I ₂ may exceed the limiting starting current value, This is detected by an overcurrent detector 31 as a current limiting function operating condition detecting means, and the electromagnetic relay 32 is turned off by a detection output of the overcurrent detector 31. As a result, the electromagnet solenoid 34 is demagnetized, and the movable body 15 is promptly moved to the position shown in FIG. 6 by the force of the tension spring 35 to contract, so that the first protrusion 11a, the movable iron piece 12, and the second protrusion A magnetic path (leakage magnetic path) passing through 11b is formed. That is, at the time of the current limiting function operation, the movable body 15 is moved to the second position where the leakage magnetic path can be formed by the movable iron piece 12.
[0022]
At this time, a slight gap is generated on the surface of the fixed iron core 11 where the first protrusion 11a, the second protrusion 11b, and the movable iron piece 12 are in contact (the sliding resistance is not generated due to the movement of the movable body 15; However, assuming that the length of this small gap is p, the magnetic resistance R _f of the magnetic path passing through the movable body 15 at the time of current limiting can be expressed as R _f = p / μ ₀ S. , P≪g, then R _f ≪R _n .
[0023]
When forming a leakage path as described above, the leakage reactance L _f viewed from the primary side becomes _{_{^{L f = n 1 2 / R}}} f. During secondary accident, because the voltage across a substantially zero in the secondary winding, phi ₂ ≒ 0, and becomes a φ ₁ ≒ φ _g. At this time, assuming that the primary voltage is V ₁ and the angular frequency is ω, the primary current I ₁ is I ₁ = V ₁ / (ωL _f ). If p is reduced and R _f is reduced, L _f is increased and I ₁ can be suppressed. That is, when an accident occurs on the secondary side, by moving the movable body 15, the fault current can be limited.
[0024]
When the accident is resolved and power transmission is resumed, the electromagnetic relay 32 is turned on again to excite the electromagnet solenoid 34, and the movable body 15 is pulled to the position shown in FIG. 5 by the generated electromagnetic force. Thus, the leakage reactance of the transformer is reduced again, and power transmission is started.
[0025]
FIG. 7 is a waveform diagram when an apparatus for demonstrating that current can be limited by moving a movable iron piece is manufactured and a test is performed. The winding ratio of the primary winding to the secondary winding was 2: 1, the secondary winding was short-circuited, and the current I _sol of the electromagnet solenoid was cut off at time 0 seconds. As can be seen from FIG. 7, after the current I _sol of the electromagnet solenoid is cut off and a time corresponding to three and a half to four cycles has elapsed, the movement of the movable iron piece is completed, and the primary current I ₁ and the secondary current I ₂ Was current-limited.
[0026]
As can be seen from FIG. 7, even after the current limiting function is activated in the transformer to which the current limiting device according to the present embodiment is applied, the current on the secondary side cannot be completely cut off. Can be suppressed to a sufficient level. In addition, since high voltage and arc are not generated in the movable part, there is an advantage that the consumption of the electrode can be suppressed.
[0027]
Also, the time from the detection of the accident to the completion of the current limiting operation (essentially, the time from the interruption of the current I _sol of the electromagnet solenoid 34 to the current limiting of the primary current I ₁ and the secondary current I _2). In order to further reduce the length, the driving mechanism may be improved by changing the tension spring 35 to one having a stronger contraction force. Of course, an electromagnet solenoid and another movable body drive mechanism other than a tension spring may be adopted to realize a higher speed movable body movement. It should be noted that what kind of mechanism is adopted as the movable body moving means is within the scope of any design matter, and it is desirable that the moving speed is faster, smaller, lighter and cheaper.
[0028]
In the above-described embodiment, the fixed iron core 11 is provided with the first protrusion 11a and the second protrusion 11b, and one movable body is positioned therebetween to form a leakage magnetic path. The method of forming the leakage magnetic path is not limited to this. The magnetic resistance of the leakage magnetic path is low when the magnetic path forming portion of the movable body is in the current limiting operation at the second position. It is only necessary that the magnetic resistance between the leakage magnetic path forming portions when the portion is in the first position during normal energization can be increased.
[0029]
【The invention's effect】
As described above, according to the current limiter according to the first aspect, when the current limiting function operating condition detecting means detects that the current limiting function operating condition has been achieved, the movable body moving means causes the movable body to move to the first position. By moving from the position to the second position, a state in which a leakage magnetic path can be formed is established, the magnetic coupling between the first winding and the second winding is switched, and a fault current due to a short circuit or the like is promptly suppressed. it can. In addition, since the normal conduction transition phenomenon of the superconducting material is not used, there is an advantage that the current limiting start current value and the return time to the normal energized state can be easily controlled.
[0030]
Further, the current limiter according to claim 1 can be used also as a transformer with a current limiting function by changing the winding ratio between the first winding and the second winding. In this case, the movable body moving means must be provided, so that the size is larger and more expensive than an ordinary transformer, but it is required for installation as compared with a case where a large-capacity current limiter is provided separately from the transformer. The space can be reduced and it can be provided at low cost. Moreover, since the winding of the transformer is originally designed to withstand the line voltage, there is an advantage that the winding can be used when the present invention is applied to an existing transformer.
[Brief description of the drawings]
FIG. 1 is a schematic structural view showing one embodiment of a current limiter according to the present invention.
FIG. 2 is a perspective view showing an appearance of a movable body in FIG.
FIG. 3 is an example in which a current limiter is applied to a transformer, and is an explanatory diagram showing a normal energized state.
FIG. 4 is an example in which a current limiter is applied to a transformer, and is an explanatory diagram showing a current limit state.
FIG. 5 is a side view of the current limiter in a normal energized state.
FIG. 6 is a side view of the current limiting device in a current limiting state.
FIG. 7 is a diagram showing waveforms of a primary voltage V ₁ , a secondary voltage V ₂ , a primary current I ₁ , a secondary current I ₂ , and a current I _sol of an electromagnet solenoid in a demonstration test of a current limiting operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Primary winding 2 Secondary winding 11 Fixed iron core 12 Moving iron piece 13 Non-magnetic support material 14 Arrow showing the moving direction of movable body 15 Moving body 21 AC power supply 22 Load 31 Overcurrent detector 32 Electromagnetic relay 33 Excitation power supply 34 Electromagnet Solenoid 35 Tension spring

Claims

給電系統に接続された一次巻線と送電系統に接続された二次巻線を経由する閉じた閉磁路を形成し得る任意形状のヨークと、
上記一次巻線と上記二次巻線の間に漏れ磁路を生ぜしめるように、上記ヨークの２点間を磁気的に結合させる任意形状の磁性材料よりなる磁路形成部を備えた可動体と、
上記可動体の磁路形成部によって漏れ磁路が形成されない第１位置と、上記可動体の磁路形成部によって漏れ磁路が形成され得る第２位置とに、上記可動体を移動させる可動体移動手段と、
予め定めた限流機能作動条件が達成されたことを検出する限流機能作動条件検出手段と、
を備え、
上記限流機能作動条件検出手段が限流機能作動条件の達成を検出することに基づいて、上記可動体移動手段が可動体を第１位置から第２位置に移動させるようにしたことを特徴とする限流器。A yoke of an arbitrary shape capable of forming a closed magnetic path via a primary winding connected to a power supply system and a secondary winding connected to a power transmission system,
A movable body having a magnetic path forming portion made of a magnetic material of an arbitrary shape for magnetically coupling between two points of the yoke so as to generate a leakage magnetic path between the primary winding and the secondary winding. When,
A movable body that moves the movable body between a first position where a leaked magnetic path is not formed by the magnetic path forming unit of the movable body and a second position where a leaked magnetic path can be formed by the magnetic path forming unit of the movable body Means of transportation;
Current limiting function operating condition detecting means for detecting that a predetermined current limiting function operating condition has been achieved,
With
The movable body moving means moves the movable body from the first position to the second position based on the fact that the current limiting function operating condition detecting means detects achievement of the current limiting function operating condition. Current limiter.