KR102490977B1 - Link scheduling method of wireless sensor network and recording media recorded program realizing the same - Google Patents

Abstract

A method and apparatus for measuring AC loss of a superconducting coil are provided. A method for measuring AC loss of a superconducting coil according to an embodiment of the present invention includes cooling the superconducting coil to a target temperature; energizing the superconducting coil with alternating current at the target temperature; checking a saturation temperature at which the superconducting coil is saturated by the alternating current; estimating heat loss of the superconducting coil based on the target temperature and saturation temperature; and measuring AC loss of the superconducting coil based on the heat loss.
The national R&D projects that supported this invention are “Task identification number: R18XA03”, “Name of supporting department: Korea Electric Power Corporation”, “Research project name: Research service”, “Research management institution: Korea Electric Power Corporation”, “Research project name : Basic technology development for floating offshore wind power generation platform based on 10 MW class superconducting wind power generator”, “Research period: 2018.03.01 ~ 2021.02.28”, “Supervisor: Changwon National University Industry-University Cooperation Foundation”.

Description

AC loss measurement method of superconducting coil and its device

The present invention relates to a method and apparatus for measuring AC loss of a superconducting coil.

In general, superconductors have a property called AC loss that does not exist in copper wires. AC loss is a loss that occurs when an AC current is energized in a superconductor. AC loss includes hysteresis loss due to internal metal of superconductor, coupling loss of conductor, and eddy current loss of structural material.

On the other hand, the loss of the superconducting coil is converted into temperature. If all losses of the superconducting coil in a low temperature state are not considered, the operating temperature of the superconducting coil is changed. Therefore, if cooling is not performed as much as the heat load due to alternating current loss or the like, the superconductor may lose superconductivity in the pyroelectric rotating machine in operation, causing a great problem in the rotating machine.

Korean Patent Publication No. 2005-0109807 (published on November 22, 2005) Republic of Korea Patent No. 0758149 (2007.09.06. Registration) Republic of Korea Patent Publication No. 2001-0093678 (published on October 29, 2001)

The present invention is to solve the above problems, and provides a method and apparatus for measuring AC loss of a superconducting coil capable of accurately measuring AC loss of the superconducting coil.

The problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

A method for measuring AC loss of a superconducting coil according to an embodiment of the present invention for achieving the above object includes cooling the superconducting coil to a target temperature; energizing the superconducting coil with alternating current at the target temperature; checking a saturation temperature at which the superconducting coil is saturated by the alternating current; estimating heat loss of the superconducting coil based on the target temperature and saturation temperature; and measuring AC loss of the superconducting coil based on the heat loss.

The measuring of the AC loss may include measuring the heat loss as an AC loss of the superconducting coil.

A method for measuring AC loss of a superconducting coil according to another embodiment of the present invention for achieving the above object includes cooling the superconducting coil to a target temperature; energizing the superconducting coil with direct current at the target temperature; checking a first temperature of the superconducting coil; estimating a first heat loss of the superconducting coil; energizing an armature coil corresponding to the superconducting coil with alternating current; checking a second temperature of the superconducting coil; estimating a second heat loss of the superconducting coil; and measuring AC loss of the superconducting coil based on the first and second heat losses.

The measuring of the AC loss may include measuring a difference between the first and second heat losses as an AC loss of the superconducting coil.

And, acquiring the current density of the superconducting coil; calculating an electric field using the current density; calculating an AC loss of the superconducting coil based on the current density and the magnetic field; and comparing the measured AC loss with the calculated AC loss.

An apparatus for measuring AC loss of a superconducting coil according to an embodiment of the present invention for achieving the above object is a superconducting coil located in a cryogenic container, a temperature sensor for measuring the temperature of the superconducting coil, and supporting the superconducting coil. a superconducting coil unit including a coil support unit; an armature coil unit including an armature coil corresponding to the superconducting coil and a magnetic shield layer positioned at one end of the armature coil; a power supply unit including an AC power supply module for applying AC current and a DC power supply module for applying DC current; and a loss measurer configured to measure a first AC loss or a second AC loss of the superconducting coil, wherein the first AC loss is generated as the temperature of the superconducting coil rises when an AC current is applied to the superconducting coil. The second AC loss is generated according to the magnetic field of the armature coil when AC current is applied to the armature coil after DC current is applied to the superconducting coil.

In addition, the superconducting coil unit may have three or more cryogenic containers.

Also, the temperature sensor may be located in a central cryogenic container among the three cryogenic containers.

In addition, the loss measurement unit cools the superconducting coil located in the cryogenic container to a target temperature, energizes the superconducting coil with AC current by the AC power module at the target temperature, and saturates the superconducting coil by the AC current. Checking a saturation temperature at which a is obtained using the temperature sensor, estimating heat loss of the superconducting coil based on the target temperature and saturation temperature, and determining the first AC loss of the superconducting coil based on the heat loss can be measured

The loss measuring unit cools the superconducting coil located in the cryogenic container to a target temperature, conducts the superconducting coil with DC current at the target temperature, and sets the first temperature of the superconducting coil to the target temperature. After confirmation using a sensor and estimating the first heat loss of the superconducting coil, the armature coil is energized with AC current by the AC power module, and the second temperature of the superconducting coil is measured using the temperature sensor and the second heat loss of the superconducting coil may be estimated, and the second AC loss of the superconducting coil may be measured based on the first and second heat losses.

Other specific details of the invention are included in the detailed description and drawings.

According to the present invention, AC loss can be measured before mounting a superconducting coil on a superconducting rotor or the like, and a cooling system of a superconducting rotor or the like can be implemented by applying the accurately measured AC loss.

1 is a diagram illustrating a sequence of a method for measuring AC loss of a superconducting coil according to an embodiment of the present invention.
2 is a diagram showing a sequence of a method for measuring AC loss of a superconducting coil according to another embodiment of the present invention.
3 is a diagram showing the configuration of an apparatus for measuring AC loss of a superconducting coil according to an embodiment of the present invention.
4 is a diagram showing the configuration of a superconducting coil unit and an armature coil unit of an apparatus for measuring AC loss of a superconducting coil according to an embodiment of the present invention.
5 is a diagram for explaining AC loss occurring in a superconducting coil and an armature coil.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the detailed description of the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, only these embodiments make the disclosure of the present invention complete, and common knowledge in the art to which the present invention belongs. It is provided to fully inform the holder of the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numbers designate like elements throughout the specification.

Although first, second, etc. are used to describe various elements, components and/or sections, it is needless to say that these elements, components and/or sections are not limited by these terms. These terms are only used to distinguish one element, component or section from another element, component or section. Accordingly, it goes without saying that the first element, first element, or first section referred to below may also be a second element, second element, or second section within the spirit of the present invention.

Terminology used herein is for describing the embodiments and is not intended to limit the present invention. In this specification, singular forms also include plural forms unless specifically stated otherwise in a phrase. As used in the specification, a referenced component, step, operation and/or element to "comprises" and/or "made of" refers to one or more other components, steps, operations and/or elements. Existence or additions are not excluded.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used in a meaning commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in commonly used dictionaries are not interpreted ideally or excessively unless explicitly specifically defined.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a diagram illustrating a sequence of a method for measuring AC loss of a superconducting coil according to an embodiment of the present invention.

Referring to FIG. 1, in the method for measuring AC loss of a superconducting coil according to an embodiment of the present invention, the superconducting coil is cooled to a target temperature (S110), and the superconducting coil is energized with AC current at the target temperature (S120). ), confirming the saturation temperature at which the superconducting coil is saturated by the alternating current (S130), estimating the heat loss of the superconducting coil based on the target temperature and saturation temperature (S140), and calculating the heat loss Based on this, AC loss of the superconducting coil is measured (S150).

When a superconducting wire is affected by an alternating current, a loss different from that occurring in a normal copper wire occurs. In general, AC loss of a single superconducting wire can be measured by current and minute voltage generated in the superconducting wire, but in the case of a superconducting coil, it is difficult to accurately define the loss of the coil.

torr 이하로 유지할 수 있다. At this time, each superconducting coil has a device such as a cryostat to maintain a low cooling temperature, and the superconducting coil can be cooled in the cryostat. Here, between the superconducting coil and the cryogenic container, MLI (Multi Layer Insulation) can be used to block heat transfer by internal convection and radiation, and to minimize heat transfer by convection and radiation, the degree of vacuum inside the cryogenic container

It can be kept below torr.

When alternating current is energized in the superconducting coil, loss due to heat load occurs in the superconducting coil in the vacuum state of the cryogenic container.

More specifically, let T0 be the temperature when the superconducting coil is cooled to reach the target temperature. After reaching the target temperature, an alternating current is energized, and a temperature at which the alternating current is saturated is measured and assumed to be T1. Heat loss of the superconducting coil can be estimated using the target temperature and the saturation temperature as shown in Equation 1 below.

는 열 손실에 의한 열량이며,

는 초전도 코일의 비열,

은 초전도 코일의 질량,

는 초전도 코일의 온도 변화이다. 상기

는 T1-T0가 된다.From here,

is the amount of heat due to heat loss,

is the specific heat of the superconducting coil,

is the mass of the silver superconducting coil,

is the temperature change of the superconducting coil. remind

becomes T1-T0.

The amount of heat estimated by Equation 1 becomes the heat loss of the superconducting coil, and the heat loss can be measured as the AC loss of the superconducting coil.

Therefore, through the AC loss measurement method of the superconducting coil according to an embodiment of the present invention, when the AC current is energized in the superconducting coil, after temperature saturation is achieved, the superconducting coil calculates the heat generation to accurately measure the AC loss.

2 is a diagram showing a sequence of a method for measuring AC loss of a superconducting coil according to another embodiment of the present invention.

Referring to FIG. 2 , in a method for measuring AC loss of a superconducting coil according to another embodiment of the present invention, the superconducting coil is cooled to a target temperature (S210), and the superconducting coil is energized with direct current at the target temperature (S220). ), the first temperature of the superconducting coil is checked (S230), and the first heat loss of the superconducting coil is estimated (S240). Then, the armature coil corresponding to the superconducting coil is energized with AC current (S250), the second temperature of the superconducting coil is checked (S260), the second heat loss of the superconducting coil is estimated (S270), AC loss of the superconducting coil is measured based on the first and second heat losses (S280).

torr 이하로 유지할 수 있다.Superconducting coils applied to large-capacity superconducting rotors apply individual cryogenic containers to each superconducting coil in order to efficiently maintain a low cooling temperature of 20 to 40K. That is, one superconducting coil is positioned in one cryogenic container. Here, between the superconducting coil and the cryogenic container, MLI (Multi Layer Insulation) can be used to block heat transfer by internal convection and radiation, and to minimize heat transfer by convection and radiation, the degree of vacuum inside the cryogenic container is increased.

It can be kept below torr.

The superconducting coil generates a constant self magnetic field by direct current, and the armature coil generates an alternating magnetic field by alternating current. At this time, an AC loss due to an alternating magnetic field induced by an AC current occurs in the superconducting coil. That is, the superconducting coil is affected by an external magnetic field by an alternating current applied to the armature coil.

First, when DC current is energized through the superconducting coil, loss due to heat load occurs in the superconducting coil in a vacuum state of the cryogenic container. In a state where current does not flow in the armature coil, when direct current flows as much as possible to create a magnetic field in the superconducting coil, a rotor using the superconducting coil is in a no-load state.

More specifically, after reaching the target temperature by cooling the superconducting coil, direct current is energized, and the current temperature by the direct current is measured. Heat loss of the superconducting coil can be estimated as shown in Equation 1 using the target temperature and the current temperature by direct current. For convenience, the temperature measured by the DC current of the superconducting coil is referred to as the first temperature, and the heat loss of the superconducting coil is referred to as the first heat loss.

Next, an alternating current flows through the armature coil, thereby generating an alternating magnetic field and causing an alternating current loss, so that the temperature of the superconducting coil rises. Heat loss of the superconducting coil can be estimated as shown in Equation 1 using the temperature rise of the superconducting coil due to the alternating magnetic field. For convenience, the temperature of the superconducting coil by the alternating current is referred to as the second temperature, and the heat loss of the superconducting coil is referred to as the second heat loss.

Then, the AC loss may be finally measured using the heat loss estimated by the DC current of the superconducting coil and the heat loss estimated by the AC current. Specifically, when measuring the AC loss, the difference between the first heat loss and the second heat loss may be measured as the AC loss of the superconducting coil.

Therefore, through the AC loss measurement method of a superconducting coil according to another embodiment of the present invention, when an external magnetic field affects a superconducting coil, heat loss calculation for each section according to the temperature change of the superconducting coil, and the external magnetic field after temperature saturation Accurate AC loss measurement is made by calculating the heating of the coil for .

In addition, the AC loss derived through the above-described AC loss measurement method of several superconducting coils can be verified by comparing it with the theoretically calculated AC loss of the superconducting coil.

More specifically, the current density of the superconducting coil is obtained, an electric field is calculated using the current density, an AC loss of the superconducting coil is calculated based on the current density and the magnetic field, and the calculated AC loss is described above. can be compared with the measured AC losses described above.

When the current density of the superconducting coil is obtained, the electric field can be calculated as in Equation 2 below.

는 전류 밀도,

는 전기장 이다. 또한,

는 특성 전기장으로

이며,

는 임계 전류 밀도이다.From here,

is the current density,

is the electric field. also,

is the characteristic electric field

is,

is the critical current density.

In addition, the AC loss of the superconducting coil can be calculated as in Equation 3 below.

는 초전도 코일의 교류 손실이며,

는 교류 전류의 주기,

는 초전도 코일의 총 부피이다.From here,

is the AC loss of the superconducting coil,

is the period of the alternating current,

is the total volume of the superconducting coil.

Through the above-described AC measurement method of several superconducting coils, it is possible to accurately measure the AC loss before applying the superconducting coil to the superconducting rotor, etc., and accordingly, it is possible to configure the cooling system of the superconducting rotor or the like by accurately reflecting the effect of the AC loss. can

3 is a diagram showing the configuration of an apparatus for measuring AC loss of a superconducting coil according to an embodiment of the present invention. 4 is a diagram showing the configuration of a superconducting coil unit and an armature coil unit of an apparatus for measuring AC loss of a superconducting coil according to an embodiment of the present invention. And, FIG. 5 is a diagram for explaining AC loss occurring in a superconducting coil and an armature coil.

Referring to FIG. 3 , an AC loss measuring device of a superconducting coil according to an embodiment of the present invention (hereinafter, referred to as an “AC loss measuring device” 100) includes a superconducting coil unit 110, an armature coil unit 120, It includes a power supply unit 130 and a loss measurement unit 140.

The superconducting coil unit 110 includes a superconducting coil 112 located in a cryogenic container 114, a temperature sensor 116 for measuring the temperature of the superconducting coil 112, and a coil supporting the superconducting coil 112. A support portion 118 may be included.

Each superconducting coil 112 is located in each cryogenic container 114 . The superconducting coil 112 serves as a field of the rotor and generates a magnetic field.

torr 이하로 유지하는 것이 바람직하다.Although not shown in the drawing, a vacuum chamber (not shown) may be connected so that the inside of the cryogenic vessel 114 in which the superconducting coil 112 is located is vacuumed. The inside is vacuumed to block heat transfer by convection and radiation, and the degree of vacuum inside the cryogenic container 114 is adjusted to maximize cooling efficiency.

It is desirable to keep below torr.

At this time, the superconducting coil unit 110 may include three or more cryogenic containers 112 . Accordingly, AC loss may be measured using three or more superconducting coils 112 . This is to check the electromagnetic field and electromagnetic force between the coils.

Referring to FIG. 4 , AC loss may be measured using a coil located in the center among three coils. To this end, the temperature sensor 116 may be connected only to the superconducting coil 112 located in the central cryogenic vessel 114 among the three cryogenic vessels 114 . Among the three superconducting coils 112 arranged side by side, the central coil is for measuring AC loss, and the superconducting coils 112 located on both sides of the center are for simulating the same situation as the superconducting rotor.

The armature coil unit 120 may include an armature coil 122 corresponding to the superconducting coil 112 and a magnetic shield layer 124 positioned at one end of the armature coil 122 . Here, the armature coil 122 may be composed of a copper coil and an iron core, and the magnetic shield layer 124 may be composed of metal or alloy.

The armature coil unit 120 is a part corresponding to one pole of an armature used in a superconducting rotor, etc., and flows an arbitrary alternating current so that the superconducting coil 112 receives the same effect as when the superconducting rotor is loaded.

The power supply unit 130 may include an AC power module 132 that applies AC current and a DC power module 134 that applies DC current.

The AC power module 132 may directly apply an AC current to the superconducting coil 112 to energize the superconducting coil 112 . Also, after applying DC current to the superconducting coil 112 , the AC power module 132 may apply AC current to the armature coil 122 .

The DC power module 134 may apply DC current to the superconducting coil 112 to conduct the superconducting coil 112 .

The loss measurer 140 may measure the first AC loss or the second AC loss.

In this case, the first AC loss occurs as the temperature of the superconducting coil 112 rises when an AC current is applied to the superconducting coil 112 . In addition, the second AC loss is generated according to the magnetic field of the armature coil 122 when the AC current is applied to the armature coil 122 after the DC current is applied to the superconducting coil 112 .

More specifically, the loss measurement unit 140 cools the superconducting coil 112 located in the cryogenic container 114 to a target temperature, and the superconducting coil 112 is cooled at the target temperature by the AC power module 132. The superconducting coil 112 is energized with alternating current, and the saturation temperature at which the superconducting coil 112 is saturated by the alternating current is checked using the temperature sensor 116, and based on the target temperature and the saturation temperature, the superconducting coil 112 ), and a first AC loss of the superconducting coil 112 may be measured based on the heat loss.

Here, the heat loss of the superconducting coil 112 caused by the AC current becomes the first AC loss. Therefore, when AC current is energized in the superconducting coil, after temperature saturation is achieved, heat generation of the superconducting coil 112 is calculated to accurately measure the AC loss.

In addition, the loss measurer 140 cools the superconducting coil 112 located in the cryogenic container 114 to a target temperature, and converts the superconducting coil 112 to a direct current at the target temperature by the DC power supply module 134. After energizing, checking the first temperature of the superconducting coil 112 using the temperature sensor 116, and estimating the first heat loss of the superconducting coil 112, the armature coil 122 is connected to the AC power module. 132, the second temperature of the superconducting coil 112 is checked using the temperature sensor 116, the second heat loss of the superconducting coil 112 is estimated, The second AC loss of the superconducting coil 112 may be measured based on the first and second heat losses.

Here, the difference between the first heat loss and the second heat loss of the superconducting coil 112 becomes the second AC loss. Therefore, when an external magnetic field affects the superconducting coil 112, the heat loss for each section according to the temperature change of the superconducting coil 112 is calculated, and the AC loss is accurately measured by calculating the heating of the coil to the external magnetic field after temperature saturation. this is done

Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art can realize that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. you will be able to understand Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting.

100: AC loss measuring device
110: superconducting coil unit
112: superconducting coil 114: cryogenic vessel
116: temperature sensor 118: coil support
120: armature coil unit
122: armature coil 124: magnetic shield layer
130: power supply unit
132 AC power module 134 DC power module
140: loss measuring unit

Claims (10)

cooling the superconducting coil to a target temperature;
energizing the superconducting coil with alternating current at the target temperature;
checking a saturation temperature at which the superconducting coil is saturated by the alternating current;
estimating heat loss of the superconducting coil based on the target temperature and saturation temperature; and
Measuring an AC loss of the superconducting coil based on the heat loss. According to claim 1,
The step of measuring the alternating current loss,
A method for measuring AC loss of a superconducting coil, comprising measuring the heat loss as an AC loss of the superconducting coil. cooling the superconducting coil to a target temperature;
energizing the superconducting coil with direct current at the target temperature;
checking a first temperature of the superconducting coil;
estimating a first heat loss of the superconducting coil;
energizing an armature coil corresponding to the superconducting coil with alternating current;
checking a second temperature of the superconducting coil;
estimating a second heat loss of the superconducting coil; and
Measuring an AC loss of the superconducting coil based on the first and second heat losses. According to claim 3,
The step of measuring the alternating current loss,
Measuring a difference between the first and second heat losses as an AC loss of the superconducting coil. According to claim 3,
obtaining current density of the superconducting coil;
calculating an electric field using the current density;
calculating an AC loss of the superconducting coil based on the current density and the magnetic field; and
Further comprising the step of comparing the measured AC loss and the calculated AC loss, AC loss measurement method of the superconducting coil. a superconducting coil unit including a superconducting coil disposed in a cryogenic container, a temperature sensor for measuring a temperature of the superconducting coil, and a coil support unit supporting the superconducting coil;
an armature coil unit including an armature coil corresponding to the superconducting coil and a magnetic shield layer positioned at one end of the armature coil;
a power supply unit including an AC power supply module for applying AC current and a DC power supply module for applying DC current; and
A loss measurement unit for measuring a first AC loss or a second AC loss of the superconducting coil,
The first AC loss occurs as the temperature of the superconducting coil rises when an AC current is applied to the superconducting coil,
The second AC loss is generated according to the magnetic field of the armature coil when an AC current is applied to the armature coil after a DC current is applied to the superconducting coil,
The superconducting coil unit, wherein the cryogenic container is three or more, the AC loss measuring device of the superconducting coil. delete According to claim 6,
The temperature sensor,
Among the three cryogenic containers, the AC loss measuring device of the superconducting coil, located in the central cryogenic container. According to claim 6,
The loss measuring unit,
A superconducting coil located in a cryogenic container is cooled to a target temperature, the superconducting coil is energized with AC current by the AC power module at the target temperature, and a saturation temperature at which the superconducting coil is saturated by the AC power is set to the temperature. Alternating current of a superconducting coil, which is confirmed using a sensor, estimating heat loss of the superconducting coil based on the target temperature and saturation temperature, and measuring the first alternating current loss of the superconducting coil based on the heat loss Loss measurement device. According to claim 6,
The loss measurement unit,
The superconducting coil located in the cryogenic container is cooled to a target temperature, the superconducting coil is energized with direct current by the DC power supply module at the target temperature, and the first temperature of the superconducting coil is checked using the temperature sensor, After estimating the first heat loss of the superconducting coil, the armature coil is energized with AC current by the AC power module, the second temperature of the superconducting coil is checked using the temperature sensor, and the superconducting coil An AC loss measuring device of a superconducting coil, which estimates a second heat loss and measures the second AC loss of the superconducting coil based on the first and second heat losses.

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