JP2014078597A - Method for measuring ac loss of superconducting coil - Google Patents
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本発明は、超電導線材を巻線して超電導変圧器,超電導リアクトル,超電導電動機,超電導発電機などの超電導機器に適用する超電導コイルの交流損失測定方法に関する。 The present invention relates to a method for measuring an AC loss of a superconducting coil that is applied to a superconducting device such as a superconducting transformer, a superconducting reactor, a superconducting motive power, or a superconducting generator by winding a superconducting wire.
超電導線材を巻線した超電導コイルは、高磁界発生手段として種々の分野で実用化が進められている。ところで、変圧器などの誘導機器への適用では、超電導コイルに交流損失(主としてヒステリシス損失,渦電流損失,誘導結合損失など)を発生することから機器の開発,実用化が遅れていたが、近年になり超電導導体素線の細線化による交流損失の小さな超電導線材の開発、さらには酸化物超電導体の出現によって、誘導機器の実用化に向けて超電導コイルの研究,開発が急速に進められている。 A superconducting coil wound with a superconducting wire has been put into practical use in various fields as a high magnetic field generating means. By the way, in application to induction devices such as transformers, AC loss (mainly hysteresis loss, eddy current loss, inductive coupling loss, etc.) occurs in superconducting coils, but the development and commercialization of devices have been delayed in recent years. With the development of superconducting wires with low AC loss by thinning the superconducting conductor wire, and the emergence of oxide superconductors, research and development of superconducting coils are rapidly progressing toward the practical application of induction devices. .
ところで、超電導コイルは超電導状態において電気抵抗がゼロであるため抵抗損失はゼロとなるが、前記のように交番電流を通電したり変動磁界を印加すると交流損失が発生する。しかも、超電導コイルを誘導機器に適用して使用する環境下では、超電導コイルをコイル容器(クライオスタット)に収容して冷凍機で冷却することから、この冷凍機の冷凍能力やコイル容器の断熱性等を考慮,検討する上で、超電導コイルの特性,特に交流損失を高い精度で測定・評価することが極めて重要となる。 By the way, although the resistance of the superconducting coil is zero in the superconducting state, the resistance loss is zero. However, when an alternating current is applied or a variable magnetic field is applied as described above, an AC loss occurs. Moreover, in an environment where the superconducting coil is applied to an induction device, the superconducting coil is housed in a coil container (cryostat) and cooled by a refrigerator, so that the refrigerating capacity of the refrigerator, the heat insulation of the coil container, etc. Therefore, it is extremely important to measure and evaluate the characteristics of superconducting coils, particularly AC loss, with high accuracy.
一方、超電導コイルの交流損失測定方法として、従来より、ワットメータ等を用いる方法や、ロックインアンプ等の位相差から求める測定方法などが知られており、その交流損失測定の概要を以下に述べる。 On the other hand, as a method for measuring the AC loss of a superconducting coil, conventionally, a method using a wattmeter or the like, a measurement method obtained from a phase difference of a lock-in amplifier, etc. are known, and an outline of the AC loss measurement is described below. .
すなわち、被測定物の超電導コイルに通電する交番電流をI、超電導コイルに発生する電圧をVとすると、交流損失Whは、 That is, when the alternating current flowing through the superconducting coil of the object to be measured is I and the voltage generated in the superconducting coil is V, the AC loss Wh is
として表される。但し、θは電流Iと発生電圧Vとの位相角である。 Represented as: Where θ is the phase angle between the current I and the generated voltage V.
即ち、交流損失Whは超電導コイルの電流Iと、電流Iと同位相分の電圧Vcosθとの積を周回積分することにより求まり、電源の周波数をf[Hz]とすると、交流損失Phは、
Ph=f×Wh [W]・・・(2)
となる。
That is, the AC loss Wh is obtained by circular integration of the product of the current I of the superconducting coil and the voltage Vcosθ corresponding to the current I and the same phase, and when the frequency of the power source is f [Hz], the AC loss Ph is
Ph = f × Wh [W] (2)
It becomes.
この場合に、通常の誘導機器のように被測定物のコイルが常電導体であれば、前記(1),(2)式にて算出される交流損失は、抵抗損失と交流損失の和となって測定される。これに対して、超電導コイルは抵抗損失がゼロであるために交流損失のみ測定されることとなるが、この場合に超電導コイルに発生する交流損失は極めて小さく、前記(1)式における位相角θは89°以上となる。したがって、通常のワットメータやロックインアンプで交流損失を測定しようとしても測定不能、あるいは測定誤差が大となって交流損失の精度の高い測定,評価が困難となる。 In this case, if the coil of the object to be measured is a normal conductor as in a normal induction device, the AC loss calculated by the equations (1) and (2) is the sum of the resistance loss and the AC loss. Measured. On the other hand, since the resistance loss of the superconducting coil is zero, only the AC loss is measured. In this case, the AC loss generated in the superconducting coil is extremely small, and the phase angle θ in the above equation (1). Is over 89 °. Therefore, even if it is attempted to measure the AC loss with a normal wattmeter or lock-in amplifier, the measurement cannot be performed, or the measurement error becomes large and it is difficult to measure and evaluate the AC loss with high accuracy.
そこで、超電導コイルの交流損失測定精度を高める測定方法として、超電導コイルの発生電圧から得た被測定電圧の誘導成分をキャンセルするいわゆる"キャンセル法"による交流損失の測定方法,およびその測定結果のレポートが報告されている(非特許文献1参照)。 Therefore, as a measurement method to improve the AC loss measurement accuracy of the superconducting coil, a so-called "cancellation method" for measuring the inductive component of the voltage to be measured obtained from the voltage generated by the superconducting coil, and a report of the measurement result Has been reported (see Non-Patent Document 1).
図4は、前記 "キャンセル法"に対応する従来例の交流損失測定回路(等価回路図)である。図4において、1は交流電源、2は被測定物の超電導コイル、3は誘導成分電圧発生コイル(ロゴスキーコイル)、4はシャント抵抗、5は演算器、6はデジタルオシロスコープである。 FIG. 4 is a conventional AC loss measuring circuit (equivalent circuit diagram) corresponding to the “cancellation method”. In FIG. 4, 1 is an AC power source, 2 is a superconducting coil of an object to be measured, 3 is an inductive component voltage generating coil (Rogowski coil), 4 is a shunt resistor, 5 is a calculator, and 6 is a digital oscilloscope.
上記の測定回路にて、交流電源1から被測定物の超電導コイル2に交番電圧を印加して超電導コイル2の発生電圧,および誘導成分電圧発生コイル3で検出した電圧を演算器5に入力し、この演算器5にて超電導コイル2の発生電圧からインダクタンス成分の電圧をキャンセル処理する。そして、演算器5の出力信号を後段のデジタルオシロスコープ6により信号処理して超電導コイル2の交流損失を測定する。
In the above measurement circuit, an alternating voltage is applied from the
次に、図4の交流損失測定回路による電流―電圧のベクトル図を図5に示す。すなわち、交流電源1からの通電により超電導コイル2に発生する電圧(両端端子電圧)はVcであり、該電圧Vcと電流I(電流Iは図4におけるシャント抵抗4の端子電圧から求める)との位相角はθとなる。ここで、発生電圧Vcのうち交流損失の測定に必要な電圧は電流Iと同位相の電圧成分Vlossであり、前記誘導成分電圧発生コイル3で検出した電圧をキャンセル電圧Vcanとして、超電導コイル2の発生電圧Vcからそのインダクタンス成分の電圧VLをキャンセル処理することで交流損失に対応する電圧Vlossが求まる。
Next, FIG. 5 shows a vector diagram of current-voltage by the AC loss measuring circuit of FIG. That is, the voltage (terminal voltage at both ends) generated in the
ところで、図4,図5で述べた従来の交流損失測定方法では測定精度の面で次記のような課題が残る。すなわち短小な超電導線材、あるいは小規模な超電導コイル(あるいは超電導巻線)等を被測定物とする実験室レベルでの測定であれば、前記位相角θがせいぜい89.5°以下のレベルであるので、先記の"キャンセル法"による測定法が有効となる。しかしながら、中・大規模の超電導変圧器や超電導リアクトル等の誘導機器に適用する超電導コイルでは、前記発生電圧Vc,誘導成分の電圧VLが大きく、しかも交流損失の測定位相角θは89.5°以上となるため、先記の"キャンセル法"でも測定誤差が大きくなって交流損失の測定精度が低くなる可能性が高い。 By the way, the conventional AC loss measuring method described with reference to FIGS. 4 and 5 still has the following problems in terms of measurement accuracy. That is, if the measurement is performed at the laboratory level using a short superconducting wire or a small superconducting coil (or superconducting winding) as the object to be measured, the phase angle θ is at most 89.5 ° or less. The measurement method based on the above "cancellation method" is effective. However, in superconducting coils applied to induction devices such as medium- and large-scale superconducting transformers and superconducting reactors, the generated voltage Vc and inductive component voltage V L are large, and the AC loss measurement phase angle θ is 89.5 ° or more. Therefore, the above-mentioned “cancellation method” is likely to increase the measurement error and reduce the AC loss measurement accuracy.
本発明は上記の点に鑑みなされたものであり、その目的は前記課題を解決して誘導機器に適用する超電導コイルの交流損失を高い精度で測定,評価できるように改良した超電導コイルの交流損失測定方法を提供することにある。 The present invention has been made in view of the above points, and its object is to solve the above-mentioned problems and to improve the AC loss of a superconducting coil that can be measured and evaluated with high accuracy. It is to provide a measurement method.
上記目的を達成するために本発明によれば、超電導線材を巻回してなる超電導コイルを交番電圧,あるいは交番電流にて通電する際に発生する交流損失の測定方法において、予め抵抗値を測定した無誘導抵抗を前記超電導コイルに並列に接続し、超電導コイルおよび無誘導抵抗の両端電圧と通電電流との積により求めた損失から、無誘導抵抗による損失分を差し引いて超電導コイルの交流損失を求めるものとする。 In order to achieve the above object, according to the present invention, a resistance value is measured in advance in a method for measuring an AC loss generated when a superconducting coil formed by winding a superconducting wire is energized with an alternating voltage or an alternating current. Non-inductive resistance is connected in parallel to the superconducting coil, and AC loss of the superconducting coil is obtained by subtracting the loss due to non-inductive resistance from the loss obtained by the product of the voltage across the superconducting coil and non-inductive resistance and the conduction current. Shall.
上記測定方法のように、予め抵抗値を測定した無誘導抵抗を被測定物の超電導コイルに並列に接続して求めた損失から、無誘導抵抗による損失分を差し引いて(キャンセル処理)交流損失を求めることにより、図4,図5で述べた先記の"キャンセル法"において測定誤差が大きくなる位相角θが89.5°以上の領域においても精度の高い交流損失測定が可能となる。また、本発明による測定方法の測定結果は、有限要素法による磁場解析を基にした計算結果とよく一致していることが確認されている。 Subtract the loss due to the non-inductive resistance from the loss obtained by connecting the non-inductive resistance whose resistance was measured in advance to the superconducting coil of the object to be measured as in the above measurement method (cancellation processing) to obtain the AC loss. As a result, the AC loss can be measured with high accuracy even in the region where the phase angle θ is 89.5 ° or more where the measurement error increases in the above-described “cancellation method” described with reference to FIGS. Further, it has been confirmed that the measurement result of the measurement method according to the present invention is in good agreement with the calculation result based on the magnetic field analysis by the finite element method.
以下、本発明による超電導コイルの交流損失測定方法を図1〜図3に示す実施例に基づいて説明する。なお、図1の測定回路図において、図4に対応する部材には同じ符号を付してその説明は省略する。 Hereinafter, a method for measuring the AC loss of a superconducting coil according to the present invention will be described based on the embodiments shown in FIGS. In the measurement circuit diagram of FIG. 1, members corresponding to those in FIG.
本発明の超電導コイルの交流損失測定方法に基づく図1の測定回路(等価回路)においては、図4に示した従来の"キャンセル法"による交流損失測定回路を基本として、被測定物の超電導コイル2と並列に予め抵抗値を測定した無誘導抵抗7を追加接続している。 In the measurement circuit (equivalent circuit) of FIG. 1 based on the AC loss measurement method for a superconducting coil of the present invention, the superconducting coil of the object to be measured is based on the AC loss measuring circuit of the conventional “cancellation method” shown in FIG. 2 is connected in parallel with a non-inductive resistor 7 whose resistance value has been measured in advance.
なお、この無誘導抵抗7は被測定物の超電導コイルの規模によっても異なるがその目安として数kΩ〜数十kΩの抵抗を使用し、あらかじめ図1の測定回路から超電導コイル2を外して無誘導抵抗7のみ接続した状態で、無誘導抵抗7の端子電圧を検出してその抵抗損失を求めておく。次に、図1のように、測定回路に超電導コイル2と無誘導抵抗7を並列接続した状態で交流損失を測定する。
The non-inductive resistance 7 varies depending on the size of the superconducting coil of the object to be measured. As a guide, a resistance of several kΩ to several tens of kΩ is used, and the
次に、図1の測定回路による電流−電圧のベクトル図を図2示す。なお、図2のベクトル図には図5における電圧Vc(超電導コイル2の発生電圧)を併記している。 Next, FIG. 2 shows a vector diagram of current-voltage by the measurement circuit of FIG. 2 also shows the voltage Vc (generated voltage of the superconducting coil 2) in FIG.
すなわち、図2のベクトル図において、無誘導抵抗7を並列接続した超電導コイル2の両端子間に発生する端子電圧Vc2は、電流Iと同位相の交流損失と無誘導抵抗7の抵抗損失との合成電圧Vtと、超電導コイル2のリアクトル成分による電圧VLとのベクトル和となる。なお、無誘導抵抗7の誘導成分はゼロであり、よって電流Iと同位相の前記合成電圧Vtより得られる損失は、[超電導コイル2の交流損失]+[無誘導抵抗7の抵抗損失]となる。
That is, in the vector diagram of FIG. 2, the terminal voltage Vc2 generated between both terminals of the
そこで、前記合成電圧Vtより得られた損失から、先記のように予め抵抗値を測定しておいた無誘導抵抗7の抵抗損失分を演算器5にて差し引くことにより、超電導コイル2の交流損失を求めることができる。しかも、超電導コイル2に無誘導抵抗7を並列接続することにより、図2のベクトル図における測定位相角φを、同ベクトル図中に併記した電圧Vc(無誘導抵抗7を接続しない図4の測定回路に対応)の位相角θよりも小さくすることが可能であり、これにより前記の"キャンセル法"で精度の高い交流損失の測定が可能となる。
Therefore, the AC loss of the
図3は、被測定物の超電導コイル2に無誘導抵抗7を接続した図1の測定回路、および無誘導抵抗7を接続しない図4の測定回路にて、発明者等が実際に測定して得た超電導コイル2の交流損失測定結果を、有限要素法の磁場解析に基づく計算値と対比して表した図である。
3 shows the measurement circuit of FIG. 1 in which the non-inductive resistor 7 is connected to the
この測定結果から判るように、超電導コイル2に無誘導抵抗7を並列接続した測定回路(図1参照)による測定法では、電流の小さい領域での交流損失が小さすぎるために測定結果の精度に多少のエラーが見られるものの、電流の大きい領域では計算値ともよく一致している。これに対して無誘導抵抗7を接続しない従来の測定回路(図4参照)で測定した結果では、電流の大きい領域においても大きな測定エラーが残る。この測定結果から、本発明による測定法では、超電導コイルの交流損失測定精度を高めて適正に評価できることが確認できた。
As can be seen from this measurement result, in the measurement method using the measurement circuit (see FIG. 1) in which the non-inductive resistor 7 is connected in parallel to the
1:交流電源
2:超電導コイル
3:誘導成分電圧発生コイル
4:シャント抵抗
5:演算器
6:デジタルオシロスコープ
7:無誘導抵抗
1: AC power supply 2: Superconducting coil 3: Inductive component voltage generating coil 4: Shunt resistance 5: Calculator 6: Digital oscilloscope 7: Non-inductive resistance
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CN108802499A (en) * | 2018-08-16 | 2018-11-13 | 华中科技大学 | A kind of device and method of Measurement of Superconducting Magnet A.C.power loss |
CN108802499B (en) * | 2018-08-16 | 2023-11-14 | 华中科技大学 | Device and method for measuring alternating current loss of superconducting magnet |
CN109884402A (en) * | 2018-12-20 | 2019-06-14 | 华中科技大学 | A kind of acquisition methods of three-dimensional asymmetric structured high temperature Ac Losses of Superconducting Magnet |
CN109884402B (en) * | 2018-12-20 | 2020-02-14 | 华中科技大学 | Method for acquiring alternating current loss of high-temperature superconducting magnet with three-dimensional asymmetric structure |
CN117871987A (en) * | 2023-12-11 | 2024-04-12 | 国网上海市电力公司 | Long-distance superconducting cable loss detection method |
CN117871987B (en) * | 2023-12-11 | 2024-09-03 | 国网上海市电力公司 | Long-distance superconducting cable loss detection method |
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