CN115347684A - CT energy taking device for wide-range current change of high-voltage power transmission line - Google Patents

CT energy taking device for wide-range current change of high-voltage power transmission line Download PDF

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Publication number
CN115347684A
CN115347684A CN202211058229.1A CN202211058229A CN115347684A CN 115347684 A CN115347684 A CN 115347684A CN 202211058229 A CN202211058229 A CN 202211058229A CN 115347684 A CN115347684 A CN 115347684A
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China
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energy
diode
unit
phase rectification
storage unit
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CN202211058229.1A
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Chinese (zh)
Inventor
曹建安
角远亮
彭佳
孟格非
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Xian Jiaotong University
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Xian Jiaotong University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/005—Mechanical details of housing or structure aiming to accommodate the power transfer means, e.g. mechanical integration of coils, antennas or transducers into emitting or receiving devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/14—Arrangements for reducing ripples from dc input or output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/06—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode

Abstract

The invention discloses a CT energy-taking device facing wide-range current change of a high-voltage transmission line, which comprises: the energy acquisition unit is connected with the single-phase rectification unit and is used for providing electric energy for the single-phase rectification unit; the single-phase rectification unit is connected with the filtering energy storage unit, and the single-phase rectification unit and the filtering energy storage unit are simultaneously grounded; the filtering energy storage unit is connected with an equivalent load RL; the single-phase rectification unit rectifies the electric energy; the filtering energy storage unit filters the electric energy and improves the output power. The invention collects stable energy through the magnetic core under the condition of current change in the voltage transmission line; and stable and sufficient energy is provided for the load through rectification and filtering treatment; the purpose of providing stable electric energy for on-line monitoring equipment in a high-voltage power transmission system is achieved.

Description

CT energy taking device for wide-range current change of high-voltage power transmission line
Technical Field
The invention belongs to the technical field of electromagnetic induction, and relates to a CT energy-taking device for wide-range current change of a high-voltage transmission line.
Background
Along with the increasing degree of intelligence of the power system, various wireless online monitoring devices are often assembled in the high-voltage power transmission system, and the devices monitor the state of the high-voltage power transmission system in real time. However, the high voltage environment of the transmission line makes it a challenge to design a safe power supply for the monitoring device.
In a high-voltage environment, the safety, the output stability and the anti-interference capability of the power supply should be fully considered. Common methods for supplying power to online equipment in high-voltage transmission lines include: the system comprises a battery power supply mode, a solar power supply mode, a laser power supply mode, a current transformer on-line power taking mode and the like. Among the disadvantages of battery power are limited capacity, short battery life, and the need for periodic replacement. Solar power has the disadvantages of low conversion efficiency, limited power and greater weather exposure. The disadvantages of laser power supply are complex principle, high implementation difficulty and high cost. The current transformer type power taking mode utilizes the electromagnetic induction principle to take power from a high-voltage transmission line, and has larger power taking power and low cost. Because the power collected by the CT is in direct proportion to the current of the transmission line, the power collected by the secondary side is in positive correlation with the current on the high-voltage transmission line. If faults such as short circuit, grounding and the like occur to the high-voltage transmission line, the current of the high-voltage transmission line can be increased sharply, so that the energy taken by the energy taking device is excessive, the current transformer is caused to generate heat seriously, and even the energy taking device is directly damaged.
In order to solve the problems of the current transformer type energy-taking device, a large number of studies have been made by researchers, and methods such as an impedance matching method, a design-dedicated control circuit, and a hybrid power supply method have been proposed. But the defects of the methods are also obvious, the impedance matching method is complex in principle and difficult to realize, and a large amount of calculation verification is needed; designing a dedicated control circuit increases the complexity and cost of the system; the hybrid power supply method not only increases the cost and complexity of the energy-taking device, but also has an influence on the stability of the system.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides a CT energy acquisition device for high-voltage power transmission line with wide current change, which can acquire stable energy through an easily-saturated magnetic core under the condition of current change in a voltage power transmission line; and provide stable and sufficient energy for the load through rectification and filtering; the purpose of providing stable electric energy for on-line monitoring equipment in a high-voltage power transmission system is achieved.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
a CT energy-taking device for wide range of current variation of a high-voltage power transmission line, comprising: the device comprises an energy acquisition unit, a single-phase rectification unit, a filtering energy storage unit and an equivalent load RL;
the energy acquisition unit is connected with the single-phase rectification unit and is used for providing electric energy for the single-phase rectification unit; the single-phase rectification unit is connected with the filtering energy storage unit, and the single-phase rectification unit and the filtering energy storage unit are grounded simultaneously; the filtering energy storage unit is connected with an equivalent load RL; the single-phase rectification unit rectifies the electric energy; the filtering energy storage unit filters the electric energy and improves the output power.
The invention is further improved in that:
the energy acquisition unit comprises a magnetic core, an electric power transmission line and a secondary winding;
the magnetic core is a circular ring; the power transmission line passes through the center of the magnetic core; the secondary winding is uniformly wound on the surface of the magnetic core; the secondary winding is connected with the single-phase rectification unit;
the magnetic core is an easily saturated magnetic core; the saturation magnetic induction intensity Bs of the magnetic core is less than or equal to 0.6T; the maximum relative magnetic conductivity mu max is more than or equal to 1000000; the magnetic hysteresis loop rectangle ratio Br/Bs is more than or equal to 0.9; the loss Ps of the magnetic core is less than or equal to 65W/kg under the conditions of 50Hz frequency and 0.4T magnetic induction.
The energy acquisition unit is used for providing the electric energy to single-phase rectifier unit, specifically is: the power transmission line generates a changing magnetic field when current flows through the power transmission line, and the changing magnetic field excites an induction voltage in the secondary winding and is input to the single-phase rectification unit.
The waveform of the induction voltage is centrosymmetric alternating-current voltage; in a half cycle, the absolute value of the volt-second product of the induced voltage is constant.
The secondary winding is a coil obtained by uniformly winding a magnetic core on an enameled wire.
The single-phase rectification unit comprises a diode D1, a diode D2, a diode D3 and a diode D4; the anode of the diode D1 is respectively connected with the cathode of the diode D2 and one output end of the secondary winding, the anode of the diode D2 is respectively connected with the anode of the diode D4, the grounding end and the filtering energy storage unit, the cathode of the diode D4 is respectively connected with the anode of the diode D3 and the other output end of the secondary winding, and the cathode of the diode D3 is connected with the cathode of the diode D1 and the filtering energy storage unit.
The filtering energy storage unit comprises a plurality of capacitor groups Cf, an output terminal P1-1 and an output terminal P1-2;
several capacitor banks Cf are connected in parallel with each other, including: a first capacitor bank Cf, a last capacitor bank Cf and a middle capacitor bank Cf;
one end of the first capacitor bank Cf is connected with the cathode of the diode D3 and one end of the adjacent middle capacitor bank Cf respectively, and the other end of the first capacitor bank Cf is connected with the anode of the diode D4 and the other end of the adjacent middle capacitor bank Cf; one end of the last capacitor bank Cf is connected with the output terminal P1-1 and one end of the previous capacitor bank Cf respectively; the other end of the last capacitor bank Cf is connected with the output terminal P1-2 and the other end of the previous capacitor bank Cf; the output terminals P1-1 and P1-2 are connected to an equivalent load RL.
The diode D1, the diode D2, the diode D3, and the diode D4 are schottky diodes.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, when the easily-saturated magnetic core is used for CT, the voltage-second product of the secondary winding is a constant value, the energy acquisition unit, the single-phase rectification unit, the filtering energy storage unit and the equivalent load RL are sequentially cascaded, the energy acquisition unit provides electric energy and sequentially flows through the single-phase rectification unit and the filtering energy storage unit, and the single-phase rectification unit and the filtering energy storage unit respectively rectify and filter the electric energy and improve the output power; and finally to the equivalent load RL. The invention can realize the purpose of providing stable electric energy for the on-line monitoring equipment in the high-voltage power transmission system.
Furthermore, the current flows through the power transmission line to generate a changing magnetic field, and the changing magnetic field excites an induction voltage in the secondary winding and inputs the induction voltage to the single-phase rectification unit; can effectively provide stable voltage.
The invention has simple design, stable output and strong surge current resistance.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.
FIG. 1 is a schematic diagram of a CT energy-taking device facing a wide-range current change of a high-voltage transmission line;
fig. 2 is a hysteresis loop of an easily saturable core.
The device comprises an energy acquisition unit, a 2-single-phase rectification unit, a 3-filtering energy storage unit, a 4-magnetic core, a 5-secondary winding and a 6-power transmission line.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. are used for indicating the orientation or positional relationship based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship which is usually arranged when the product of the present invention is used, the description is merely for convenience and simplicity, and the indication or suggestion that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, cannot be understood as limiting the present invention. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.
Furthermore, the term "horizontal", if present, does not mean that the component is required to be absolutely horizontal, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
In the description of the embodiments of the present invention, it should be further noted that unless otherwise explicitly stated or limited, the terms "disposed," "mounted," "connected," and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
The invention is described in further detail below with reference to the accompanying drawings:
referring to fig. 1, the present invention discloses a CT energy-taking device facing a wide range of current variation of a high-voltage power transmission line, comprising: the device comprises an energy acquisition unit 1, a single-phase rectification unit 2, a filtering energy storage unit 3 and an equivalent load RL;
the energy acquisition unit 1 is connected with the single-phase rectification unit 2, and the energy acquisition unit 1 is used for providing electric energy for the single-phase rectification unit 2; the single-phase rectification unit 2 is connected with the filtering energy storage unit 3, and the single-phase rectification unit 2 and the filtering energy storage unit 3 are grounded simultaneously; the filtering energy storage unit 3 is connected with an equivalent load RL; the single-phase rectification unit 2 rectifies the electric energy; the filtering energy storage unit 3 filters the electric energy and improves the output power. The energy acquisition unit 1 comprises a magnetic core 4, an electric power transmission line 6 and a secondary winding 5; the magnetic core 4 is a circular ring; the electrical power transmission line 6 passes through the centre of the magnetic core 4; the secondary winding 5 is uniformly wound on the surface of the magnetic core 4; the secondary winding 5 is connected to the single-phase rectification unit 2. The energy acquisition unit 1 is used for providing electric energy for the single-phase rectification unit 2, and specifically is: the electric power transmission line 6 generates a changing magnetic field by flowing a current, and the changing magnetic field excites an induced voltage in the secondary winding 5 and is input to the single-phase rectification unit 2. The waveform of the induction voltage is an alternating voltage with central symmetry; the absolute value of the volt-second product of the induced voltage is constant during each half cycle. The secondary winding 5 is a coil obtained by uniformly winding the enameled wire around the magnetic core 4.
The magnetic core 4 is an easily saturated magnetic core; the saturable core has a high magnetic permeability, and thus can have a high magnetic permeability when the saturable core is not saturated to generate a sufficiently large induced electromotive force. The saturation magnetic induction density Bs of the magnetic core 4 is less than or equal to 0.6T; the maximum relative magnetic permeability mu max is more than or equal to 1000000; the rectangle ratio Br/Bs of the magnetic hysteresis loop is more than or equal to 0.9; the loss Ps of the magnetic core 4 is less than or equal to 65W/kg under the conditions of 50Hz frequency and 0.4T magnetic induction.
The coercive force Hr and the saturation magnetic induction Bs of the magnetic material are very small, and the hysteresis loop is a rectangle with a very small area, so that the hysteresis loss is very low. When the magnetic material is used as a core, the induced voltage generated in the secondary winding 5 has a characteristic that the absolute value of the volt-second product is constant.
The single-phase rectification unit 2 comprises a diode D1, a diode D2, a diode D3 and a diode D4; the anode of the diode D1 is respectively connected with the cathode of the diode D2 and one output end of the secondary winding 5, the anode of the diode D2 is respectively connected with the anode of the diode D4, the grounding end and the filtering energy storage unit 3, the cathode of the diode D4 is respectively connected with the anode of the diode D3 and the other output end of the secondary winding 5, and the cathode of the diode D3 is connected with the cathode of the diode D1 and the filtering energy storage unit 3.
The filtering energy storage unit 3 comprises a plurality of capacitor groups Cf, an output terminal P1-1 and an output terminal P1-2;
several capacitor banks Cf are connected in parallel with each other, including: a first capacitor bank Cf, a last capacitor bank Cf and a middle capacitor bank Cf;
one end of the first capacitor bank Cf is connected with the cathode of the diode D3 and one end of the adjacent middle capacitor bank Cf respectively, and the other end of the first capacitor bank Cf is connected with the anode of the diode D4 and the other end of the adjacent middle capacitor bank Cf; one end of the last capacitor bank Cf is connected with the output terminal P1-1 and one end of the previous capacitor bank Cf respectively; the other end of the last capacitor bank Cf is connected with the output terminal P1-2 and the other end of the previous capacitor bank Cf; the output terminals P1-1 and P1-2 are connected to an equivalent load RL.
The diode D1, the diode D2, the diode D3, and the diode D4 are schottky diodes.
Referring to fig. 2, the principle of the present invention that the volt-second product is constant is described: in the hysteresis loop, the saturation induction at the point B is represented by B s Corresponding to a saturation magnetic field strength of H s . In the figure, point a represents the remanence B r Coercive force of H r 。
Wherein i p (t) represents the current in the high-voltage power transmission line, when i p (t) increasing from zero to i t1 When the magnetization point on the hysteresis loop moves from point a' to point b on the curve. In this process, the magnetic induction B is changed from B r Is changed into B s At this time, the secondary winding of the energy collecting unit generates an induced electromotive force v s (t) of (d). When i is p (t) continues to increase to i p-pk At value, the magnetization curve moves from point b to point c. In this process, the core is always in a saturated state, and the change in magnetic flux density from the point b to the point c is zero. According to the electromagnetic induction principle, the secondary winding of the energy acquisition unit hardly generates induced electromotive force at this time, and it can be considered that v is s (t) is zero. When the current i in the power transmission line p (t) after entering the negative half-cycle, the principle is the same, the process is similar, and v produced in this stage s (t) the voltage is negative. The shaded area in FIG. 1 representsV generation in CT secondary winding s (t) time period.
Further, according to the ampere-loop theorem, the magnetic field strength H is: h = k · i p And k is determined by the number of turns of a secondary winding on a magnetic ring in the energy acquisition unit and the effective magnetic path length of the magnetic core. When H is H s When i is p Reach saturation current i t1 . When the easily saturable material is determined, H s Is a fixed value, i t1 Also a fixed value. As shown in fig. 1, regardless of i p How the value of (t) varies, the current i t1 The variations of (a) are all very slight. Therefore, the analysis can know that the saturation time is t at the moment by combining the experimental data 1 。
i p (t) is represented by i p (t)＝i p-pk Sin (2 π f t), where f is the voltage frequency. When the current value is i t1 Time, corresponding time t 1 Can be represented by formula (1):
Figure BDA0003825888290000071
from the above equation (1), t 1 With i being p (t) is increased and decreased.
According to the law of electromagnetic induction, the induced voltage in the coil of the energy collection unit can be expressed as formula (2):
v s (t)＝-N·ΔB·S/Δt (2)
for a core that is easily saturable, Δ t in equation (2) is the unsaturated run time, which is equivalent to t in FIG. 1 1 Or t 2 . Δ B is a fixed value based on the core material, denoted as 2B in FIG. 1 s . N is the number of turns of the secondary winding, S is the cross-sectional area of the core, and is a fixed value when the core size is determined.
The aforementioned volt-second product is Λ, and is expressed by the following formula (3):
Λ＝v s (t)·Δt＝-N·2B s ·S (3)
as can be seen from the foregoing, when the magnetic core 4 is determined, the parameters on the right side of the equation (3) are all known fixed values. Thus, the volt-second productThe value of Λ is also fixed. Further, let T be the current i p (t) period, average voltage U output by secondary winding of CT o 2 Λ/T, again of fixed value, and is not influenced by the current i in the transmission line p (t) influence of; can be expressed as:
Figure BDA0003825888290000072
the invention comprises an energy acquisition unit 1, a single-phase rectification unit 2 and a filtering energy storage unit 3 which are cascaded in sequence.
Specifically, an outgoing line of a secondary winding 5 in the energy acquisition unit 1 is a connecting terminal connected with a lower unit; the alternating current side of a rectifier bridge in the single-phase rectification unit 2 is connected with two terminals and is connected with a secondary winding 5 of a CT in the energy acquisition unit 1; similarly, the dc side has two connection terminals for connection to the filtering and energy storage unit 3.
Capacitor bank C of filtering energy storage unit 3 f The left and right sides are respectively connected with two terminals. The two terminals on the left side are front connection terminals for the unit to be cascaded with the single-phase rectification unit 2; two terminals on the right side are output terminals P 1-1 And P 1-2 For connecting an equivalent load RL. This example finally passes through P 1-1 And P 1-2 Energy is output for the load.
Due to the current i in the high-voltage power transmission line p (t) is a line-frequency AC current, so that when the current i p (t) saturation current I not reaching the core s During the process, the secondary winding of the CT in the energy acquisition unit generates corresponding induced electromotive force, and the induced electromotive force is rectified by the single-phase rectification unit and then is transmitted to the capacitor bank C f And an equivalent load RL; when i is p (t) when increased to a certain value, the magnetic field it generates causes the core to saturate. At this time, the secondary winding of the CT no longer generates induced electromotive force, and the CT no longer extracts energy from the high-voltage power transmission line. Therefore, the capacitor bank C at this time f The equivalent load RL is supplied with energy separately.
The specific working steps of this embodiment are as follows:
1. the power transmission line is passed through a magnetic loop in the energy harvesting unit.
2. The current in the power transmission line excites a magnetic field in a magnetic ring of the energy acquisition unit, and when the instantaneous value of the current in the power transmission line is smaller than the saturation current of the magnetic core, the magnetic core of the CT works in a non-saturation state mode, and induced electromotive force with the time duration of delta t can be induced in the secondary winding.
3. The induced electromotive force in the step 2 is converted into direct current pulse voltage v through the single-phase rectification unit s (t)。
4. When the DC pulse voltage v in step 3 s (t) is less than the capacitor bank C in the filtering energy storage unit f When the voltage is applied, the induced energy and the capacitor set C f The discharged energy together powers the load.
5. When the DC pulse voltage in the step 3 is larger than the capacitor bank C f When the voltage is applied, the energy collected by the energy collecting unit is the capacitor bank C f And charging, and supplying power to the equivalent load RL.
6. When the CT magnetic ring in the energy collecting unit 1 works in a saturation state, that is, the current in the power transmission line is larger than the saturation current, the induced electromotive force induced by the secondary winding 5 is negligibly small.
7. The induced electromotive force described in step 6 is too small to pass through the single-phase rectification unit. Therefore, this part of the energy is not transferred to the capacitor bank C f In this way, the conclusion that the volt-second product is constant is not influenced. I.e. the average voltage U output by the secondary winding mentioned above o The energy stability of the collection can not be influenced.
8. When a magnetic ring of a CT in the energy acquisition unit works in a saturation state mode, a capacitor bank C in the filtering energy storage unit f The released electric energy alone supplies the equivalent load RL.
9. In the above power supply process of step 8, the energy storage capacitor bank C f The capacity value is large enough, the electric energy is enough, and the voltage U does not appear o Down to 0.
10. For the embodiments of the present invention, the CT is in a discontinuous energy-taking state, but because of the single-phase rectificationThe presence of the element and the filtering energy-storage unit enables the voltage U output on the transmission terminal o Is a continuous direct current voltage with small ripples.
It is particularly worth noting that in the process from step 2 to step 8, the second product of the voltage generated by the secondary winding is a constant value as long as the magnetic field generated by the current of the high-voltage power transmission line exists within a period at which the easily saturable core can be brought into a saturation state.
The invention utilizes the characteristic that the easily-saturated magnetic material is easily saturated to ensure that the CT in the energy acquisition unit works in an intermittent energy taking mode, thereby improving the current application range of the energy taking device; the thermal stability of the CT energy taking device is improved by utilizing the characteristics of small hysteresis loop area and small iron loss of the easily-saturated magnetic core; the output stability and the anti-surge current capability of the energy taking device are improved by utilizing the characteristic that the volt-second product is a constant value; and finally, a single-phase rectifying unit and a filtering energy storage unit are designed to improve the output power.
The present invention has been described in terms of the preferred embodiment, and it is not intended to be limited to the embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. A CT energy-taking device for wide-range current variation of a high-voltage power transmission line, comprising: the device comprises an energy acquisition unit (1), a single-phase rectification unit (2), a filtering energy storage unit (3) and an equivalent load RL;
the energy acquisition unit (1) is connected with the single-phase rectification unit (2), and the energy acquisition unit (1) is used for providing electric energy for the single-phase rectification unit (2); the single-phase rectification unit (2) is connected with the filtering energy storage unit (3), and the single-phase rectification unit (2) and the filtering energy storage unit (3) are simultaneously grounded; the filtering energy storage unit (3) is connected with an equivalent load RL; the single-phase rectification unit (2) rectifies electric energy; the filtering energy storage unit (3) filters the electric energy and improves the output power.
2. The CT energy-extraction device facing wide range of current variations of high voltage transmission lines according to claim 1, characterized in that said energy-harvesting unit (1) comprises a magnetic core (4), an electric power transmission line (6) and a secondary winding (5);
the magnetic core (4) is a circular ring; said electrical power transmission line (6) passing through the centre of the magnetic core (4); the secondary winding (5) is uniformly wound on the surface of the magnetic core (4); the secondary winding (5) is connected with the single-phase rectifying unit (2);
the magnetic core (4) is an easily saturated magnetic core; the saturation magnetic induction intensity Bs of the magnetic core (4) is less than or equal to 0.6T; the maximum relative magnetic conductivity mu max is more than or equal to 1000000; the magnetic hysteresis loop rectangle ratio Br/Bs is more than or equal to 0.9; the loss Ps of the magnetic core (4) is less than or equal to 65W/kg under the conditions of 50Hz frequency and 0.4T magnetic induction.
3. The CT energy-extraction device facing high voltage transmission lines with wide range of current variation according to claim 2, characterized in that the energy-harvesting unit (1) is used to provide electric energy to the single-phase rectification unit (2), specifically: the power transmission line (6) generates a changing magnetic field by flowing current, and the changing magnetic field excites an induced voltage in the secondary winding (5) and is input to the single-phase rectification unit (2).
4. The CT energy extraction device facing wide range of current variation of high voltage transmission line according to claim 3, characterized in that the waveform of the induced voltage is a centrosymmetric AC voltage; in a half cycle, the absolute value of the volt-second product of the induced voltage is constant.
5. The CT energy extraction device facing wide range of current variation of high voltage transmission line according to claim 4, characterized in that the secondary winding (5) is a coil obtained by uniformly winding enameled wire around the magnetic core (4).
6. The CT energy-extraction device facing high-voltage transmission lines with wide range of current variations according to claim 5, characterized in that said single-phase rectification unit (2) comprises a diode D1, a diode D2, a diode D3 and a diode D4; the positive pole of diode D1 connects diode D2's negative pole and an output of secondary winding (5) respectively, and diode D2's positive pole is connected diode D4's positive pole, ground connection and filtering energy storage unit (3) respectively, and diode D4's negative pole is connected diode D3's positive pole and another output of secondary winding (5) respectively, and diode D3's negative pole is connected diode D1's negative pole and filtering energy storage unit (3).
7. The CT energy-taking device facing high voltage transmission lines with wide range of current variation according to claim 6, characterized in that said filtering energy-storage unit (3) comprises several capacitor banks Cf, output terminals P1-1 and P1-2;
the plurality of capacitor groups Cf are connected in parallel with each other, and include: a first capacitor group Cf, a last capacitor group Cf and a middle capacitor group Cf;
one end of the first capacitor bank Cf is connected with the cathode of the diode D3 and one end of the adjacent middle capacitor bank Cf respectively, and the other end of the first capacitor bank Cf is connected with the anode of the diode D4 and the other end of the adjacent middle capacitor bank Cf; one end of the last capacitor bank Cf is connected with the output terminal P1-1 and one end of the previous capacitor bank Cf respectively; the other end of the last capacitor bank Cf is connected with the output terminal P1-2 and the other end of the previous capacitor bank Cf; the output terminal P1-1 and the output terminal P1-2 are connected with an equivalent load RL.
8. The CT energy-extracting device for wide range of current variation facing high voltage transmission lines according to claim 7, characterized in that the diodes D1, D2, D3 and D4 are schottky diodes.
CN202211058229.1A 2022-08-31 2022-08-31 CT energy taking device for wide-range current change of high-voltage power transmission line Pending CN115347684A (en)

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