CN111650415B - Self-powered current detection system and detection method for wide-current-band power transmission line - Google Patents
Self-powered current detection system and detection method for wide-current-band power transmission line Download PDFInfo
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- CN111650415B CN111650415B CN202010516480.2A CN202010516480A CN111650415B CN 111650415 B CN111650415 B CN 111650415B CN 202010516480 A CN202010516480 A CN 202010516480A CN 111650415 B CN111650415 B CN 111650415B
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
- G01R15/183—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core
- G01R15/185—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using transformers with a magnetic core with compensation or feedback windings or interacting coils, e.g. 0-flux sensors
Abstract
The invention discloses a self-powered current detection system and a self-powered current detection method for a wide-current-band power transmission line, wherein the system comprises a current detection device and an energy taking device, wherein the current detection device is sleeved on the power transmission line and is used for primary side current detection, and the energy taking device provides electric energy for the current detection device; the energy-taking magnetic core always works in a linear region through information transmission and compensation excitation current effective value and phase parameter configuration of the induction energy-taking device and the current detection device. Compared with the traditional current detection device, the current detection device has the advantages that the current precision detection and the real-time energy supply of the active circuit module under the condition of large current fluctuation range are realized, the energy-taking magnetic core always works in a linear area by combining the information transmission of the induction energy-taking device and the current detection device and compensating the excitation current key parameter configuration, the service life of the energy-taking magnetic core is effectively prolonged, and the accident rate of electrical equipment is reduced.
Description
Technical Field
The invention relates to hanging type current detection of a high-voltage power transmission and transformation line and a real-time power supply technology thereof, in particular to a self-powered current detection system and a detection method of a wide-current-band power transmission line.
Background
The power transmission and transformation circuit of the power system is used as an important carrier of power transmission, the real-time current detection significance is great, and due to safety considerations, the circuit current detection device cannot be directly additionally arranged on a circuit cable, so that the non-contact current detection device is required to be operated. Due to the influence of the exciting current in the magnetic core of the current detection device on the detection precision, the ratio of the primary side current to the secondary side current and the number of turns are difficult to form an inverse proportional relation, so that the amplitude and the phase of the secondary side current need to be compensated. At present traditional passive compensation mode is replaced by active compensation mode gradually, the measurement grade of current detection device has been improved to a very big degree, but it is difficult at the active partial energy source of current detection device of high latitude to articulate, in view of the fortune dimension cost, the circuit response can get the mode and become for a comparatively suitable energy supply mode, but traditional response can get the mode when circuit current fluctuates on a large scale, can't acquire certain energy at a certain moment by the energy-taking device, perhaps lead to generating heat seriously at another moment because the magnetic core supersaturation, damage can get device itself.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a self-powered current detection system for a wide-current-band power transmission line, which can realize accurate current detection and real-time energy supply of an active circuit module in a large current fluctuation range.
Another object of the present invention is to provide a detection method of the current detection system, wherein the energy-extracting magnetic core always works in a linear region by information transfer and compensation of the induction energy-extracting device and the current detection device, and effective value and phase parameter configuration of the excitation current.
The technical scheme is as follows: the self-powered current detection system for the wide-current-band power transmission line comprises a current detection device and an energy taking device, wherein the current detection device and the energy taking device are sleeved on the power transmission line, the current detection device is used for primary side current detection, and the energy taking device provides electric energy for the current detection device.
Preferably, the current detection device comprises a current detection main magnetic core, a current detection auxiliary magnetic core, a detection winding I, a feedback winding, a detection winding II, a compensation winding I and a high-precision sampling resistor ZpThe current detection device comprises a detection winding I and a feedback winding, wherein the detection winding I and the feedback winding are wound on a current detection main magnetic core, the detection winding II and the compensation winding I are wound on a current detection auxiliary magnetic core, the current detection auxiliary magnetic core is nested in an inner ring of the current detection main magnetic core, a power transmission line penetrates through the inner ring of the current detection auxiliary magnetic core, the feedback winding and the compensation winding I are connected through the current detection device excitation current compensation unit, and the detection winding I and the detection winding II are connected through a high-precision sampling resistor ZpConnected with a signal processing unit and a high-precision sampling resistor ZpAre connected in parallel.
Preferably, the exciting current compensation unit of the current detection device comprises a signal amplification circuit I, a filter circuit I, a phase shift circuit I, a V-I conversion circuit I and a micro control unit I, wherein the signal amplification circuit I, the filter circuit I, the phase shift circuit I and the V-I conversion circuit I are sequentially connected in series, the micro control unit I is respectively connected with the signal amplification circuit I, the phase shift circuit I and the V-I conversion circuit I, the signal amplification circuit I has a high input impedance characteristic and realizes signal amplification of induced electromotive force of the feedback winding, the phase shift angle of the phase shift circuit I is 90 degrees or-270 degrees, and the micro control unit I judges the condition of magnetic flux in an iron core according to the magnitude of the induced electromotive force in the feedback winding and controls the current amplitude passing through the compensation winding I in real time.
Preferably, the energy taking device comprises an energy taking magnetic core, an energy taking winding, a compensation winding II, an energy taking device exciting current compensation unit, a switch unit, an energy processing unit, a super capacitor C and an energy distribution unit, wherein the energy taking magnetic core and a current detection main magnetic core of the current detection device are arranged in parallel, a power transmission line penetrates through an inner ring of the energy taking magnetic core, the energy taking winding and the compensation winding II are wound on the energy taking magnetic core, the input end of the energy taking device exciting current compensation unit is connected with the output end of the signal processing unit, the output end of the energy taking device exciting current compensation unit is connected with the compensation winding II through the switch unit, the energy taking winding is connected with the energy processing unit, the output end of the energy processing unit is connected with the energy distribution unit, the super capacitor C is connected in parallel, and the output end of the energy distribution unit is respectively connected with the current detection device exciting current compensation unit, The signal processing unit and the energy taking device exciting current compensation unit are connected with the energy input end of the switch unit.
Preferably, the signal processing unit comprises a signal amplifying circuit II, a filter circuit II and a V-I conversion circuit II which are sequentially connected in series, and the signal amplifying circuit II is used for sampling the high-precision sampling resistor ZpThe filter circuit II filters high-frequency signals by adopting a low-pass filter circuit, the V-I conversion circuit II performs voltage-current conversion on the filtered voltage signals, so that the measurement of primary side current is realized, and output current is taken as an energy taking deviceAn input current of the exciting current compensating unit.
Preferably, the excitation current compensation unit signal of the energy taking device comprises a signal amplification circuit III, a phase shift circuit II and a micro control unit II, wherein the signal amplification circuit III and the phase shift circuit II are sequentially connected in series, and the micro control unit II is respectively connected with the signal amplification circuit III and the phase shift circuit II; the signal amplification circuit III is used for carrying out amplitude amplification processing on the output current of the signal processing module, the phase shift circuit II is used for taking a phase shift measure on the amplified current, and the micro control unit II is used for adjusting the amplitude and the phase of the compensation current by using the signal amplification circuit III and the phase shift circuit II based on the energy taking magnetic core magnetomotive force balance principle.
Preferably, the switch unit includes a voltage comparator i, a voltage comparator ii, a filter circuit iii, a filter circuit IV, a drive circuit i, a drive circuit ii, a voltage relay i, and a voltage relay ii, the voltage comparator i, the filter circuit iii, the drive circuit i, and the voltage relay i are sequentially connected in series, the filter circuit iii performs an amplitude stabilizing function on the output of the voltage comparator i, removes a signal spike caused by crosstalk, and the drive circuit i improves the capability of the voltage comparator i to drive the voltage relay i after filtering; the voltage comparator II, the filter circuit IV, the driving circuit II and the voltage relay II are sequentially connected in series, the filter circuit IV plays a role in stabilizing the output of the voltage comparator II, signal spikes caused by crosstalk are removed, and the driving circuit II improves the capability of the voltage comparator II for driving the voltage relay II after filtering;
the voltage relay I and the voltage relay II are both in a normally open state and are connected in parallel, after being connected in parallel, the voltage relay I and the voltage relay II form a series circuit with an excitation current compensation unit and a compensation winding II, action signals of the two voltage relays are respectively controlled by high and low levels output by respective voltage comparators, the nonlinear characteristic that an energy-taking magnetic core changes along with the current of a power transmission and transformation line is input in advance, and input signals of the two voltage comparators are primary side current RMS (I is the input signal of the primary side current RMS)1) The reference signals are respectively RMS (I)1min) And RMS (I)1max)，I1minMinimum current of power transmission and transformation circuit representing starting charging state of super capacitor, and starting charging state of super capacitor representing minimum currentThe current flowing through the super capacitor is equal to the leakage current and is at I1minThe exciting current under the working environment is I0min， I1maxThe current of the power transmission and transformation line indicating that the energy-taking magnetic core is in a critical saturation state is I1maxThe excitation current under the working environment is I0max。
Preferably, the energy processing unit comprises a rectifying circuit and a filtering circuit V, the rectifying circuit converts the inductive alternating current output by the energy taking device into direct current, and the filtering circuit V filters ripple components of the direct current.
The detection method of the self-powered current detection system of the wide-current-band power transmission line comprises the following steps:
(1) induced voltage detected by a feedback winding in a current detection main magnetic core generates compensation current through an excitation current compensation unit of the current detection device, the current generates reverse excitation magnetomotive force through a compensation winding I, so that the current detection main magnetic core is in a zero magnetic flux state, the excitation current is reduced to an extremely low level, and the signal processing circuit conditions the high-precision sampling resistance voltage signal to realize primary side current detection;
(2) if the switch unit judges that the primary side current is less than RMS (I)1min) The digital signal control switch is closed, the energy taking device exciting current compensation unit controls the compensation winding II to be in a current forward excitation state, and the current forward excitation state shows that the energy taking device compensates current and improves an exciting current effective value, so that the induced voltage is increased; if the switch module judges that the primary side current is larger than RMS (I)1max) The digital signal control switch is closed, the energy taking device exciting current compensation unit controls the compensation winding group II to be in a current reverse excitation state, and the current reverse excitation state represents that the energy taking device compensation current reduces an exciting current effective value and relieves the saturation degree of an energy taking magnetic core; if the primary side current works in the threshold current interval, the switch unit does not act, and the excitation current compensation unit of the energy taking device is in a dormant state;
(3) the energy-taking magnetic core supplies power to the super capacitor through the energy processing unit, the super capacitor supplies power to the current detection device when primary side current is over, and meanwhile, the electric energy output by the energy processing unit provides real-time energy supply of different voltage levels for the exciting current compensation unit of the current detection device, the signal processing unit, the exciting current compensation unit of the energy-taking device and the switch unit through the energy distribution unit.
Furthermore, ignoring the magnetizing current in the step (2), the configuration method of the specific parameters of the compensation amplitude and the phase of the excitation current compensation unit of the energy taking device is represented as follows:
wherein, | I3L is the effective value of the current flowing through the compensation winding II, and delta is I3And a primary side current I1Phase angle of (I)2Is the secondary side output current of the energy-taking magnetic core, and alpha is I2And e2Phase angle between e2For obtaining induced electromotive force, R, of secondary side of the magnetic coreLAnd XLRespectively a secondary side equivalent load resistance and an equivalent load reactance, RwAnd XwRespectively the equivalent resistance and the equivalent leakage impedance of the secondary side coil; reasonable configuration of parameter | I by microcontroller II3And | and delta control the excitation current of the energy-taking magnetic core within a threshold value interval.
Has the advantages that: compared with the prior art, the invention has the advantages that: (1) the primary side current can be measured with high precision by an active exciting current compensation technology. (2) The energy supply pain point of the active part of the current detection device and other electric equipment is solved. (3) The energy-taking magnetic core always works in a linear area, the service life of the energy-taking magnetic core is effectively prolonged, the accident rate of electrical equipment is reduced, and good social benefit and economic benefit are achieved.
Drawings
FIG. 1 is a schematic diagram of the current sensing system of the present invention;
FIG. 2 is a schematic circuit diagram of the disassembled current detection system of the present invention;
FIG. 3 is a schematic diagram of an active compensation unit of the current sensing device;
FIG. 4 is a schematic diagram of a signal processing unit;
FIG. 5 is a schematic diagram of an excitation current compensation unit of the energy extracting device;
FIG. 6 is a schematic diagram of a switching unit;
fig. 7 is a working mechanism phasor diagram of the energy-extracting magnetic core.
Detailed Description
The invention will be further described with reference to the following drawings and specific embodiments. The following are only preferred embodiments of the present invention, it being noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.
The system comprises a current detection device and an energy taking device, wherein the current detection device is used for primary side current detection, the energy taking device provides electric energy for the current detection device, and the current detection device and the energy taking device are both sleeved on a power transmission line.
As shown in FIG. 1 and FIG. 2, the current detection device comprises a main current detection core, an auxiliary current detection core, a detection winding I, a feedback winding, a detection winding II, a compensation winding I, and a high-precision sampling resistor ZpThe current detection auxiliary magnetic core is nested in an inner ring of the current detection main magnetic core, the power transmission line penetrates through an inner ring of the current detection auxiliary magnetic core, the feedback winding is connected with the compensation winding I through the current detection device exciting current compensation unit, and the detection winding I and the detection winding II are connected through a high-precision sampling resistor ZpConnected with the signal processing unit and the high-precision sampling resistor ZpAre connected in parallel. The number of turns of the detection winding I is N1The number of turns of the feedback winding is N0The number of turns of the detection winding II is N1The number of turns of the compensation winding I is N4. The exciting current compensation unit of the current detection device comprises a signal amplification circuit I, a filter circuit I, a phase shift circuit I, a V-I conversion circuit I and a micro control unit I, as shown in FIG. 3The signal amplification circuit I, the filter circuit I, the phase shift circuit I and the V-I conversion circuit I are sequentially connected in series, the micro control unit I is respectively connected with the signal amplification circuit I, the phase shift circuit I and the V-I conversion circuit I, the signal amplification circuit I has a high input impedance characteristic, signal amplification of induced electromotive force of the feedback winding is achieved, the phase shift angle of the phase shift circuit I is 90 degrees or-270 degrees, the micro control unit I judges the magnetic flux condition in an iron core according to the magnitude of the induced electromotive force in the feedback winding, current amplitude flowing through the compensation winding I is controlled in real time, and the influence of exciting current on current detection precision is eliminated to the maximum extent.
The energy taking device comprises an energy taking magnetic core, an energy taking winding, a compensation winding II, an energy taking device exciting current compensation unit, a switch unit, an energy processing unit, a super capacitor and an energy distribution unit, wherein the energy taking magnetic core and a current detection main magnetic core are arranged in parallel, a power transmission line penetrates through the inner ring of the energy taking magnetic core, the energy taking winding and the compensation winding II are wound on the energy taking magnetic core, and the number of turns of the energy taking winding is N2The number of turns of the compensation winding II is N3The input end of the excitation current compensation unit of the energy taking device is connected with the output end of the signal processing module, the output end of the excitation current compensation unit of the energy taking device is connected with the compensation winding II through the switch unit, the energy taking winding is connected with the energy processing unit, the output end of the energy processing unit is connected with the energy distribution unit, the super capacitor C is connected in parallel, and the output end of the energy distribution unit is respectively connected with the excitation current compensation unit of the current detection device, the signal processing unit, the excitation current compensation unit of the energy taking device and the energy input end of the switch unit.
The current detection main magnetic core, the current detection auxiliary magnetic core and the energy taking magnetic core are made of nanocrystalline magnetically soft alloy, the current detection main magnetic core and the energy taking magnetic core are arranged in parallel, and the current detection auxiliary magnetic core is nested in the inner ring of the current detection main magnetic core, so that the occupancy rate of a high-level space of a power transmission and transformation circuit is effectively reduced.
As shown in fig. 4, the signal processing unit includes a signal amplifying circuit ii, a filter circuit ii, and a V-I conversion circuit ii, the signal amplifying circuit ii, the filter circuit ii, and the V-I conversion circuit ii are connected in series in this order, and the signal amplifying circuit iiCircuit II pair high precision sampling resistance ZpThe voltage value of the energy taking device is amplified, a low-pass filter circuit is adopted by the filter circuit II to filter high-frequency signals, the voltage-current conversion is carried out on the filtered voltage signals by the V-I conversion circuit II, so that the measurement of primary side current is realized, and output current is used as input current of an excitation current compensation unit of the energy taking device.
As shown in fig. 5, the excitation current compensation unit of the energy taking device comprises a signal amplification circuit iii, a phase shift circuit ii and a micro control unit ii, wherein the signal amplification circuit iii and the phase shift circuit ii are sequentially connected in series, and the micro control unit ii is respectively connected with the signal amplification circuit iii and the phase shift circuit ii. The amplifying circuit III is used for amplifying the amplitude of the output current of the signal processing module, the phase-shifting circuit II is used for taking a phase-shifting measure for the amplified current, and the micro-control unit II is used for adjusting the amplitude and the phase of the compensation current by using the amplifying circuit III and the phase-shifting circuit II based on the energy-taking magnetic core magnetomotive force balance principle.
As shown in fig. 6, the switch unit includes a voltage comparator i, a voltage comparator ii, a filter circuit iii, a filter circuit iv, a driver circuit i, a driver circuit ii, a voltage relay i, and a voltage relay ii. The voltage comparator I, the filter circuit III, the driving circuit I and the voltage relay I are sequentially connected in series, the filter circuit III plays an amplitude stabilizing role in outputting of the voltage comparator I, signal spikes caused by crosstalk are removed, the driving circuit I improves the capacity of the voltage comparator I for driving the voltage relay I after filtering, and the signal loading capacity is improved. The voltage comparator II, the filter circuit IV, the driving circuit II and the voltage relay II are sequentially connected in series, the filter circuit IV plays a role in stabilizing the output of the voltage comparator II, signal spikes caused by crosstalk are removed, and the driving circuit II improves the capability of the voltage comparator II for driving the voltage relay II after filtering.
As shown in fig. 2, both the voltage relay i and the voltage relay ii are in a normally open state and are connected in parallel, and after being connected in parallel, the voltage relay i and the voltage relay ii form a series circuit with the excitation current compensation unit and the compensation winding ii, and the operation signals of the two voltage relays are respectively controlled by the high and low levels output by the respective voltage comparators and are input in advanceThe nonlinear characteristic of the energy-taking magnetic core changing along with the current of the power transmission and transformation line, the input signals of the two voltage comparators are primary side current RMS (I)1) The reference signals are respectively RMS (I)1min) And RMS (I)1max) Said I is1minThe minimum current of the power transmission and transformation circuit represents the starting charging state of the super capacitor, the starting charging state of the super capacitor represents that the current flowing through the super capacitor is equal to the leakage current and is in the I1minThe exciting current under the working environment is I0minSaid I is1maxThe current of the power transmission and transformation line indicating that the energy-taking magnetic core is in a critical saturation state is in the I1maxThe exciting current under the working environment is I0max。
The energy processing unit comprises a rectifying circuit and a filter circuit V, the rectifying circuit converts induction alternating current output by the energy taking device into direct current, and the filter circuit V filters ripple components of the direct current.
The detection method comprises the following steps:
(1) induced voltage detected by a feedback winding in a current detection main magnetic core generates compensation current through an excitation current compensation unit of the current detection device, the current generates reverse excitation magnetomotive force through a compensation winding I, so that the current detection main magnetic core is in a zero magnetic flux state, the excitation current is reduced to an extremely low level, and the signal processing circuit conditions the high-precision sampling resistance voltage signal to realize primary side current detection. The method specifically comprises the following steps:
the radius and the thickness of the inner and the outer rings of the circular ring of the current detection main magnetic core are respectively R1，R2And h1The radius and the thickness of the inner and the outer rings of the circular ring of the current detection auxiliary magnetic core are respectively R5，R6And h3The radius and thickness of the inner and outer rings of the ring of the energy-taking magnetic core are respectively R3，R4And h2The magnetomotive force balance equations of the main magnetic core and the auxiliary magnetic core of the current detection device before compensation are respectively as follows:
wherein, I1For the primary side of the transmission line current, I01And I02Excitation currents, I, of the main and auxiliary cores, respectively, of the pre-compensation current detection device1' to compensate for the current flowing through the high precision sampling resistor before, as obtained from the above formula, I01＝I02The magnetomotive force balance equations of the main magnetic core and the auxiliary magnetic core of the compensated current detection device are respectively as follows:
wherein, I01 #And I02 #Excitation currents, I, of main and auxiliary cores, respectively, of the pre-compensation current-sensing device1"is the current flowing through the high-precision sampling resistor after compensation, I5For the compensation current flowing through the compensation winding I, only N is needed4I5＝I02 #The main magnetic core of the system satisfies the 'zero magnetic flux' state, I1"and I1Absence of phase difference by measuring I1' the current I of the primary side power transmission line can be converted according to the turn ratio1Wherein the voltage of high accuracy sampling resistor is provided by the reverse excitation electromotive force that compensation winding I produced, and current detection device main magnetic core feedback winding induced voltage is:
then:
wherein rho is the distance from any point in the main magnetic core of the current detection device to the center of the circle, and omega is the current I of the primary side transmission line1F is the primary side transmission line current I1Frequency of (1), N0The number of turns of the feedback winding. The exciting current and the induced electromotive force in the current detection main magnetic coreThe phase difference is 90 degrees or-270 degrees, mu is the magnetic permeability of the nanocrystalline soft magnetic alloy, AkAnd the current detection device is used for amplifying the exciting current compensation unit.
(2) If the switch module judges that the primary side current is less than RMS (I)1min) The digital signal controls the voltage relay II to be closed, the energy taking device exciting current compensation unit controls the compensation winding II to be in a current forward excitation state, and the current forward excitation state represents that the energy taking device compensates current and improves an exciting current effective value, so that the induction voltage is increased; if the switch module judges that the primary side current is larger than RMS (I)1max) The digital signal controls the voltage relay I to be closed, the energy taking device exciting current compensation unit controls the compensation winding II to be in a current reverse excitation state, and the current reverse excitation state represents that the energy taking device compensation current reduces an exciting current effective value and relieves the saturation degree of an energy taking magnetic core; and if the primary side current works in the threshold current interval, the switch unit does not act, and the excitation current compensation unit of the energy taking device is in a dormant state. The method specifically comprises the following steps:
under the same condition of exciting current of the current detection main magnetic core and the current detection auxiliary magnetic core, in order to enable the compensation winding I and the feedback winding to generate the same induced electromotive force, the current detection main magnetic core and the auxiliary magnetic core structure need to meet the following requirements:
wherein R is the radius of the power transmission and transformation line. In addition, neglecting the magnetizing current, the following analytical formula can be obtained from the energy-taking core working phase diagram shown in FIG. 7, N2Number of turns of winding for taking energy, N3In order to compensate the number of turns of the winding II,
is equivalent load resistance power factor angle, delta is compensation current I3And bus current I1Phase angle of (1), I3The current value output by the exciting current compensation unit of the energy taking device, I0And I0' is the exciting current value of the energy-taking magnetic core before and after the excitation current compensation of the energy-taking device, and alpha is I2And E2Phase angle between and I2Hysteresis E2，E2And E2The effective value of the induced electromotive force of the secondary side of the energy-taking magnetic core before and after the compensation of the exciting current of the energy-taking device is I2And I2' secondary side current value before and after compensation for excitation current of energy taking device, U2Compensating the equivalent load voltage value of the front and the secondary sides for the exciting current of the energy taking device, ZLFor secondary side equivalent load impedance, and for simplifying analysis, keeping secondary side equivalent load impedance Z before and after excitation current compensation of energy taking deviceLInvariable, RLAnd XLRespectively an equivalent load resistance and an equivalent load reactance, RwAnd XwRespectively, the equivalent resistance and the equivalent leakage impedance of the secondary side coil.
Therefore, neglecting the magnetizing current, the specific parameter configuration method for compensating amplitude and phase of the excitation current compensation unit of the energy taking device is represented as follows:
wherein, | I3I is the effective value of the current flowing through the compensation winding II, and a parameter I is reasonably configured through the microcontroller II3I and delta can be used for converting the excitation current I of the energy-taking magnetic core0' control is within a threshold interval.
(3) The energy-taking magnetic core supplies power to the super capacitor through the energy processing unit, the super capacitor supplies power to the current detection device when primary side current passes through, and meanwhile, electric energy output by the energy processing unit is supplied to the current detection device exciting current compensation unit, the signal processing unit, the energy-taking device exciting current compensation unit and the switch unit through the energy distribution unit respectively to supply real-time energy of different voltage levels.
Claims (8)
1. A self-powered current detection system of a wide-current-band power transmission line is characterized by comprising a current detection device and an energy taking device, wherein the current detection device and the energy taking device are sleeved on the power transmission line;
the energy taking device comprises an energy taking magnetic core, an energy taking winding, a compensation winding II, an energy taking device exciting current compensation unit, a switch unit, an energy processing unit, a super capacitor C and an energy distribution unit, wherein the energy taking magnetic core and a current detection main magnetic core of the current detection device are arranged in parallel, a power transmission line penetrates through an inner ring of the energy taking magnetic core, the energy taking winding and the compensation winding II are wound on the energy taking magnetic core, the input end of the energy taking device exciting current compensation unit is connected with the output end of the signal processing unit, the output end of the energy taking device exciting current compensation unit is connected with the compensation winding II through the switch unit, the energy taking winding is connected with the energy processing unit, the output end of the energy processing unit is connected with the energy distribution unit, the super capacitor C is connected in parallel, and the output end of the energy distribution unit is respectively connected with the current detection device exciting current compensation unit, the signal processing unit, the super capacitor C, the output end of the energy distribution unit is respectively connected with the current detection device exciting current compensation unit, the signal processing unit, the switch unit, the super capacitor C is connected with the energy distribution unit, the super capacitor C, the energy distribution unit, the super capacitor C is connected with the energy distribution unit, the super capacitor C is connected with the super capacitor C, the super capacitor C is connected with the energy distribution unit, the energy distribution unit is connected with the energy distribution unit, and the energy distribution unit, the energy distribution unit is connected with the energy distribution unit, and the energy distribution unit is connected with the energy distribution unit, and the energy distribution unit is connected with the energy distribution unit, and the energy distribution unit is connected with the energy distribution unit, and the energy distribution unit is connected with the energy distribution unit, and the energy distribution unit, The energy taking device exciting current compensation unit is connected with the energy input end of the switch unit;
the switch unit comprises a voltage comparator I, a voltage comparator II, a filter circuit III, a filter circuit IV, a drive circuit I, a drive circuit II, a voltage relay I and a voltage relay II, wherein the voltage comparator I, the filter circuit III, the drive circuit I and the voltage relay I are sequentially connected in series, the filter circuit III plays an amplitude stabilizing role in the output of the voltage comparator I, signal spikes caused by crosstalk are removed, and the drive circuit I improves the capacity of the voltage comparator I to drive the voltage relay I after filtering; the voltage comparator II, the filter circuit IV, the driving circuit II and the voltage relay II are sequentially connected in series, the filter circuit IV plays a role in stabilizing the output of the voltage comparator II, signal spikes caused by crosstalk are removed, and the driving circuit II improves the capability of the voltage comparator II for driving the voltage relay II after filtering;
the voltage relay I and the voltage relay II are both in a normal stateThe two voltage relays are respectively controlled by high and low levels output by respective voltage comparators, and are input with nonlinear characteristics of the energy-taking magnetic core changing along with the current of the power transmission line in advance, and input signals of the two voltage comparators are primary side current RMS (I)1) The reference signals are respectively RMS (I)1min) And RMS (I)1max)，I1minThe minimum current of the power transmission and transformation circuit represents the starting charging state of the super capacitor, the starting charging state of the super capacitor represents that the current flowing through the super capacitor is equal to the leakage current and is in I1minThe exciting current under the working environment is I0min，I1maxThe current of the power transmission and transformation line indicating that the energy-taking magnetic core is in a critical saturation state is I1maxExcitation current under working environment is I0max。
2. The system of claim 1, wherein the current detection device comprises a main current detection core, an auxiliary current detection core, a first detection winding, a feedback winding, a second detection winding, a first compensation winding, and a high-precision sampling resistor ZpThe current detection device comprises a detection winding I and a feedback winding, wherein the detection winding I and the feedback winding are wound on a current detection main magnetic core, the detection winding II and the compensation winding I are wound on a current detection auxiliary magnetic core, the current detection auxiliary magnetic core is nested in an inner ring of the current detection main magnetic core, a power transmission line penetrates through an inner ring of the current detection auxiliary magnetic core, the feedback winding and the compensation winding I are connected through the current detection device excitation current compensation unit, and the detection winding I and the detection winding II are connected through a high-precision sampling resistor ZpConnected with the signal processing unit and the high-precision sampling resistor ZpAre connected in parallel.
3. The self-powered current detection system of the wide-current transmission line according to claim 2, wherein the current detection device exciting current compensation unit comprises a signal amplification circuit I, a filter circuit I, a phase shift circuit I, a V-I conversion circuit I, a micro control unit I, a signal amplification circuit I, the filter circuit I, the phase-shifting circuit I and the V-I conversion circuit I are sequentially connected in series, the micro-control unit I is respectively connected with the signal amplification circuit I, the phase-shifting circuit I and the V-I conversion circuit I, the signal amplification circuit I is high in input impedance characteristic and can amplify signals of induced electromotive force of the feedback winding, the phase-shifting angle of the phase-shifting circuit I is 90 degrees or-270 degrees, the micro-control unit I judges the condition of magnetic flux in an iron core according to the magnitude of the induced electromotive force in the feedback winding and controls the current amplitude flowing through the compensation winding I in real time.
4. The self-powered current detection system of the wide-current transmission line according to claim 1, wherein the signal processing unit comprises a signal amplification circuit II, a filter circuit II and a V-I conversion circuit II which are sequentially connected in series, and the signal amplification circuit II samples a high-precision sampling resistor ZpThe voltage value of the energy taking device is amplified, a low-pass filter circuit is adopted by the filter circuit II to filter high-frequency signals, the voltage-current conversion is carried out on the filtered voltage signals by the V-I conversion circuit II, so that the measurement of primary side current is realized, and output current is used as input current of an excitation current compensation unit of the energy taking device.
5. The system for detecting the self-powered current of the wide-current-band power transmission line according to claim 1, wherein the signal of the excitation current compensation unit of the energy taking device comprises a signal amplification circuit III, a phase-shifting circuit II and a micro-control unit II, the signal amplification circuit III and the phase-shifting circuit II are sequentially connected in series, and the micro-control unit II is respectively connected with the signal amplification circuit III and the phase-shifting circuit II; the signal amplification circuit III is used for carrying out amplitude amplification processing on the output current of the signal processing module, the phase shift circuit II is used for carrying out phase shift on the amplified current, and the micro control unit II is used for adjusting the amplitude and the phase of the compensation current by the signal amplification circuit III and the phase shift circuit II based on the energy-taking magnetic core magnetomotive force balance principle.
6. The self-powered current detection system of the wide-current power transmission line according to claim 1, wherein the energy processing unit comprises a rectifying circuit and a filtering circuit V, the rectifying circuit converts the induced alternating current output by the energy taking device into direct current, and the filtering circuit V filters ripple components of the direct current.
7. The detection method of the self-powered current detection system of the wide-band power transmission line of any one of claims 1 to 6, characterized by comprising the following steps:
(1) induced voltage detected by a feedback winding in a current detection main core generates compensation current through an excitation current compensation unit of the current detection device, the current generates reverse excitation magnetomotive force through a compensation winding I, so that the current detection main core is in a zero magnetic flux state, the excitation current is reduced to an extremely low level, and the signal processing circuit conditions a high-precision sampling resistance voltage signal to realize primary side current detection;
(2) if the switch unit judges that the primary side current is less than RMS (I)1min) The digital signal controls the voltage relay II to be closed, the energy taking device exciting current compensation unit controls the compensation winding II to be in a current forward excitation state, and the current forward excitation state represents that the energy taking device compensates current and improves an exciting current effective value, so that the induction voltage is increased; if the switch module judges that the primary side current is larger than RMS (I)1max) When the digital signal control voltage relay I is closed, the energy taking device exciting current compensation unit controls the compensation winding II to be in a current reverse excitation state, and the current reverse excitation state shows that the energy taking device compensation current reduces an exciting current effective value and relieves the saturation degree of an energy taking magnetic core; if the primary side current works in the threshold current interval, the switch unit does not act, and the excitation current compensation unit of the energy taking device is in a dormant state;
(3) the energy-taking magnetic core supplies power to the super capacitor through the energy processing unit, the super capacitor supplies power to the current detection device when primary side current is over, and meanwhile, the electric energy output by the energy processing unit provides real-time energy supply of different voltage levels for the exciting current compensation unit of the current detection device, the signal processing unit, the exciting current compensation unit of the energy-taking device and the switch unit through the energy distribution unit.
8. The detection method of the self-powered current detection system of the wide-current transmission line according to claim 7, wherein the magnetizing current is ignored in the step (2), and the configuration method of the specific parameters of the compensation amplitude and the compensation phase of the excitation current compensation unit of the energy-taking device is represented as:
wherein, | I3L is the effective value of the current flowing through the compensation winding II, and delta is I3And a primary side current I1Phase angle of (I)2Is the secondary side output current of the energy-taking magnetic core, and alpha is I2And e2Phase angle between e2For obtaining induced electromotive force, R, of secondary side of the magnetic coreLAnd XLRespectively a secondary side equivalent load resistance and an equivalent load reactance, RwAnd XwEquivalent resistance and equivalent leakage impedance of the secondary side coil, N2Number of turns of winding for taking energy, N3For compensating for number of turns of winding II, R3，R4The radius of the inner circle and the outer circle of the ring of the energy-taking magnetic core respectively, mu is the magnetic conductivity of the nanocrystalline magnetically soft alloy, and f is the current I of the primary side power transmission line1Frequency of (I)0' is the exciting current value of the energy-taking magnetic core after the exciting current compensation of the energy-taking device; reasonable configuration of parameter | I by microcontroller II3And | and delta control the excitation current of the energy-taking magnetic core within a threshold interval.
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