CN103558467A - Capacitive equipment on-line monitoring device based on anisotropy magnetic resistance bridge - Google Patents

Abstract

The invention discloses a capacitive equipment on-line monitoring device based on an anisotropy magnetic resistance bridge. The capacitive equipment on-line monitoring device comprises a monitoring circuit. The input end of the monitoring circuit is marked to be an end A, the two output ends of the monitoring circuit are marked to be an end B and an end C respectively, and the grounding end of the monitoring circuit is marked to be an end D. The monitoring circuit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor and a sixth resistor, wherein the end A is connected with the output end of capacitive equipment, the first resistor and the third resistor are connected between the end A and the end C after being connected in series, the sixth resistor is connected between the end A and the end B, the fifth resistor is connected between the end C and the end D, the second resistor and the fourth resistor are connected between the end B and the end D after being connected in series, the first resistor and the second resistor are fixed resistors with the same resistance, the third resistor and the fourth resistor are first anisotropic magnetic resistors with the same zero field specific resistance, and the fifth resistor and the sixth resistor are second anisotropic magnetic resistors with the same zero field specific resistance. By means of the capacitive equipment on-line monitoring device based on the anisotropy magnetic resistance bridge, synchronous real-time measurement can be truly realized.

Description

A kind of capacitive apparatus on-Line Monitor Device based on anisotropic magnetic conducting bridge

Technical field

The present invention relates to electric system measurement and on-line monitoring technique field, be specifically related to a kind of capacitive apparatus on-Line Monitor Device based on anisotropic magnetic conducting bridge, the real time on-line monitoring sensor that especially a kind of employing anisotropic magneto-resistive effect (AMR) magneto-resistor is sensing element.

Background technology

Capacitive apparatus refers to that insulation system adopts the electrical equipment of electric capacity, and the bushing shell for transformer in current system, current transformer, capacitance type potential transformer, coupling condenser etc., all belong to such, and quantity accounts for 40%～50% of Substation Electric Equipment.High voltage capacitive apparatus is long-term in service, and due to the impact of the factors such as filth, chemical corrosion, electrocorrosion, heating, mechanical stress, insulating property decline gradually, may cause major defect.If do not find in time and take measures, latent defect further develops, and may cause insulation breakdown, causes device damage, and then affects the operation of transformer station, even causes large area blackout, causes tremendous economic loss to electric system and social production life.

Under normal running conditions, the capacity current of capacitive apparatus, current in resistance property and Dielectric loss tangent have characterized the performance state of equipment, when the current in resistance property of capacitive apparatus and Dielectric loss tangent are when bigger than normal, the decreasing insulating that shows this equipment, therefore to the state of capacitive apparatus as equipment voltage, device current, capacity current, current in resistance property, Dielectric loss tangent, substitutional resistance, equivalent capacitance, carry out real time on-line monitoring, can find in advance the insulation defect of capacitive apparatus, early warning is provided, and change in time the capacitive apparatus after aging, safe operation to electric system is significant.

General capacitive apparatus on-line monitoring system is mainly by voltage sensor and current sensor, to measure respectively voltage, the electric current of capacitive apparatus, by fft analysis calculating voltage amplitude, current amplitude and both phase differential, then extrapolate the information such as current in resistance property, capacity current and Dielectric loss tangent of capacitive apparatus.Because the current in resistance property of equipment is very little, dielectric loss is very little under normal circumstances, and electric current and voltage phase differential approaches 0.And general capacitive apparatus on-line monitoring system is because voltage and circuit signal are to gather respectively, therefore the synchronous requirement both being gathered is very high, very little temporal error may cause the error of current in resistance property, capacity current and Dielectric loss tangent very large, easily cause erroneous judgement, cause trouble to the operation of normal transformer station.

Therefore for the shortcoming of the current technology of appeal, the present invention is under National 863 planning item fund (2012AA050209) is subsidized, and has proposed a kind of capacitive apparatus on-line monitoring method and device based on anisotropic magnetic conducting bridge.

Summary of the invention

For above-mentioned deficiency, the invention provides a kind of capacitive apparatus on-Line Monitor Device based on anisotropic magnetic conducting bridge, voltage, electric current, current in resistance property, capacity current, substitutional resistance, equivalent capacitance and the Dielectric loss tangent of its energy Real-Time Monitoring capacitive apparatus.By the measuring-signal of voltage and current being integrated in the output signal of a sensor, when reducing acquisition channel, really realize synchronous real-time measurement, avoid because of voltage, the temporal asynchronous error that causes of current acquisition, can significantly improve measuring accuracy, realize high-precision real time on-line monitoring and the fault pre-alarming of transformer station's capacitive apparatus.

For realizing above object, the technical scheme that the present invention takes is:

A kind of capacitive apparatus on-Line Monitor Device based on anisotropic magnetic conducting bridge, it comprises observation circuit and capacitive apparatus, the input end of described observation circuit is labeled as A end, two output terminal is labeled as respectively B end and C end, its earth terminal is labeled as D end, described observation circuit comprises the first resistance, the second resistance, the 3rd resistance, the 4th resistance, the 5th resistance and the 6th resistance, wherein, described A end is connected with the output terminal of capacitive apparatus, after the first resistance and the 3rd resistance serial connection, be connected between A end and C end, the 6th resistance is connected between side a and b, the 5th resistance is connected between C end and D end, after the second resistance and the 4th resistance serial connection, be connected between B end and D end, described the first resistance is the fixed resistance that resistance is identical with the second resistance, described the 3rd resistance and the 4th resistance are the first different in nature magneto-resistor that null field resistivity equates, described the 5th resistance and the 6th resistance are the second different in nature magneto-resistor that null field resistivity equates.

Described capacitive apparatus is equivalent to equivalent capacitance and the substitutional resistance being in parallel, and the one end after parallel connection is connected with A end, and the other end is connected with ground wire.

Described observation circuit adopts MEMS technique to be integrated on a chip.

Described observation circuit is close on ground wire.

The null field resistivity of described the first different in nature magneto-resistor and the second different in nature magneto-resistor all equates, and the absolute value of the sensitivity coefficient of the two is identical, and wherein, the sensitivity coefficient of the first different in nature magneto-resistor is for just, and the sensitivity coefficient of described the second different in nature magneto-resistor is for bearing.

Observation circuit is integrated on the chip that a slice is very little by MEMS technique, can be close on the ground wire of tested capacitive apparatus simultaneously, and volume is very little.The voltage output end of observation circuit gathers by the collecting device of rear end, and analyze, thereby calculate current in resistance property, capacity current, substitutional resistance, equivalent capacitance and the Dielectric loss tangent of capacitive apparatus, by the signal is far passed, to transformer station's on-line monitoring center ，Wei transformer station, provide real-time status information of equipment and fault pre-alarming simultaneously.

The computing method of the current in resistance property of derivation of equation capacitive apparatus, capacity current, substitutional resistance, equivalent capacitance and Dielectric loss tangent below.

The output voltage u=Usin ω t that makes capacitive apparatus, the current i of capacitive apparatus is:

$i=\frac{u}{R_{\mathrm{DUT}}}+C_{\mathrm{DUT}}\frac{\mathrm{du}}{\mathrm{dt}}=\frac{U\sin \mathrm{\ωt}}{R_{\mathrm{DUT}}}+\mathrm{\ω}{C}_{\mathrm{DUT}}U\cos \mathrm{\ωt}---\left(1\right)$

And the output voltage u of observation circuit _out(voltages between B, C two ends) are:

$\begin{array}{c}{u}_{\mathrm{out}}=u\·\frac{R_1+2k_{G}i}{R_1+2R_2}\\ =\frac{R_1}{R_1+2R_2}U\sin \mathrm{\ωt}+\frac{2k_G}{R_1+2R_2}U\sin \mathrm{\ωt}+(\frac{U\sin \mathrm{\ωt}}{R_{\mathrm{DUT}}}+\mathrm{\ω}{C}_{\mathrm{DUT}}U\cos \mathrm{\ωt})\\ =\frac{R_1}{R_1+2R_2}U\sin \mathrm{\ωt}+\frac{2k_G{U}^2}{R_1+2R_2}\frac{1}{R_{\mathrm{DUT}}}{\sin }^2\mathrm{\ωt}+\frac{{2k}_G{U}^2}{R_1+2R_2}\mathrm{\ω}{C}_{\mathrm{DUT}}\sin \mathrm{\ω}t\cos \mathrm{\ωt}\\ =\frac{k_G{U}^2}{(R_1+2R_2)R_{\mathrm{DUT}}}+\frac{R_{1}U}{R_1+2R_2}\sin \mathrm{\ωt}+\frac{k_G{U}^2\sqrt{1+{\mathrm{\ω}}^2{R}_{\mathrm{DUT}}^2{C}_{\mathrm{DUT}}^2}}{(R_1+2R_2)R_{\mathrm{DUT}}}\sin (2\mathrm{\ωt}-\arctan \frac{1}{\mathrm{\ω}{R}_{\mathrm{DUT}}{C}_{\mathrm{DUT}}})\end{array}---\left(2\right)$

Wherein u is A terminal voltage value, and i is the electric current on ground wire, k _gbe the absolute value of the sensitivity coefficient of the first different in nature magneto-resistor and the second different in nature magneto-resistor, R ₁for the resistance of fixed resistance, R ₂the zero electric field resistivity of the first different in nature magneto-resistor and the second different in nature magneto-resistor, the voltage that U is capacitive apparatus, R _dUTfor the resistance of capacitive apparatus substitutional resistance, C _dUTcapacitance for capacitive apparatus equivalent capacitance.

The output voltage of observation circuit comprises three frequency components as seen from formula (2): DC component, fundamental component and 2 harmonics.

By the output voltage of observation circuit is carried out to signal spectral analysis, the DC component that extracts signal (makes as A ₀), fundamental component (A ₁), 2 harmonic (A ₂) and the phase differential θ of fundamental component and 2 harmonics.According to above-mentioned amount, can instead release voltage, electric current, current in resistance property, capacity current, substitutional resistance, equivalent capacitance and the Dielectric loss tangent that calculates capacitive apparatus, computing method are as follows:

The voltage U of capacitive apparatus is:

$U=(1+\frac{2R_2}{R_1})A_1---\left(3\right)$

The electric current I of capacitive apparatus is:

$I=\frac{R_1{A}_1{A}_2}{k_G}---\left(4\right)$

The substitutional resistance R of capacitive apparatus _dUTfor:

$R_{\mathrm{DUT}}=\frac{R_1+2R_2}{k_G{U}^2}{A}_0---\left(5\right)$

The equivalent capacitance C of capacitive apparatus _dUTfor:

$C_{\mathrm{DUT}}=\frac{\sqrt{{\left(\frac{A_2}{A_0}\right)}^2-1}}{\mathrm{\ω}{R}_{\mathrm{DUT}}}---\left(6\right)$

The current in resistance property I of capacitive apparatus _rfor:

$I_R=\frac{U}{R_{\mathrm{DUT}}}---\left(7\right)$

The capacity current I of capacitive apparatus _cfor:

I _C=ωC _DUTU （8）

The Dielectric loss tangent tan δ of capacitive apparatus is:

t _anδ=t _anθ （9）

The present invention compared with prior art, tool has the following advantages: the present invention is by being input to capacitive apparatus voltage signal the voltage input end of observation circuit, observation circuit is clung on the ground wire of capacitive apparatus simultaneously, by induction capacitive apparatus, flow through the magnetic field that ground line current produces, thereby can instead release size of current.Observation circuit, by natural multiplication relation, is integrated into the voltage and current of tested capacitive apparatus in same signal.By harvester, this signal is carried out to collection analysis, can extrapolate voltage, electric current, current in resistance property, capacity current, substitutional resistance, equivalent capacitance and the Dielectric loss tangent of equipment, when reducing acquisition channel, really realize synchronous real-time measurement, avoid because of voltage, the temporal asynchronous error that causes of current acquisition, can significantly improve measuring accuracy, realize high-precision real time on-line monitoring and the fault pre-alarming of transformer station's capacitive apparatus.

Accompanying drawing explanation

Fig. 1 is the electrical schematic diagram that the present invention is based on the capacitive apparatus on-Line Monitor Device of anisotropic magnetic conducting bridge;

Fig. 2 is the equivalent circuit theory figure of observation circuit.

Wherein: 1, observation circuit; 11, fixed resistance; 111, resistance; 112, resistance; 12, different in nature magneto-resistor; 121, resistance; 122, resistance; 13, different in nature magneto-resistor; 131, resistance; 132, resistance; 2, capacitive apparatus; 21, equivalent capacitance; 22, substitutional resistance; 23, ground wire.

Embodiment

Below in conjunction with the drawings and specific embodiments, content of the present invention is described in further details.

Embodiment

Please refer to shown in Fig. 1, a kind of capacitive apparatus on-Line Monitor Device based on anisotropic magnetic conducting bridge, it comprises observation circuit 1 and capacitive apparatus 2, the input end of observation circuit 1 is labeled as A end, two output terminal is labeled as respectively B end and C end, its earth terminal is labeled as D end, observation circuit 1 comprises resistance 111, resistance 112, resistance 121, resistance 122, resistance 131 and resistance 132, wherein, A end is connected with the output terminal of capacitive apparatus 2, after resistance 111 and resistance 121 series connection, be connected between A end and C end, resistance 132 is connected between side a and b, resistance 131 is connected between C end and D end, after resistance 112 and resistance 122 series connection, be connected between B end and D end.In order to keep the balance of electric bridge, resistance 111 is identical with the resistance of resistance 112, and resistance 121 is identical with the resistance of resistance 122, and resistance 131 is identical with the resistance of resistance 132.Resistance 111 and resistance 112 are collectively referred to as fixed resistance 11, resistance 121, resistance 122, resistance 131 and resistance 132 all adopt different in nature magnetic resistance structure, for the ease of calculating, in the present invention, four adopt the absolute value of equal null field resistivity and four sensitivity coefficient to equate, the sensitivity coefficient of resistance 121 and resistance 122, for just, is collectively referred to as different in nature magneto-resistor 12 simultaneously, the sensitivity coefficient of resistance 131 and resistance 132, for negative, is collectively referred to as different in nature magneto-resistor 13.Certainly, as long as guarantee that the parameter of two resistance in different in nature magneto-resistor 12 is identical, in the identical situation of the parameter of two resistance in different in nature magneto-resistor 13, also can calculate.

In order in real time capacitive apparatus to be monitored by this observation circuit 1, in preferred embodiment of the present invention, six resistance of observation circuit 1 adopt MEMS techniques to be integrated on a very little chip, simultaneously, this observation circuit 1 is also close to the ground wire 23(of capacitive apparatus 2 or the connecting line of the input end of the output terminal of capacitive apparatus 2 and observation circuit 1) upper, make its volume very little.Observation circuit 1 flows through the magnetic field of the electric current generation of ground wire 23 by induction capacitive apparatus 2, thereby can instead release the size of current on ground wire 23.

The kind of capacitive apparatus 2 has a lot, but general equal equivalent capacitance 21 and the substitutional resistance 22 being in parallel that be equivalent to, its one end after parallel connection is connected with the input end of observation circuit 1 (tie point is A end) as output terminal, and its other end is connected with ground wire 23.

Please refer to shown in Fig. 2, it is the equivalent electrical circuit of this observation circuit 1, and wherein, resistance 111 and resistance 112 are equivalent to resistance R ₁₁and resistance R ₁₂, its resistance is R ₁; Resistance 121 and resistance 122 are equivalent to resistance R ₁₃and resistance R ₁₄, its resistance is R ₂, be+k of its sensitivity coefficient _g, so the two resistance value while being affixed on ground wire 23 is R ₂+ k _gi(wherein i is the electric current on ground wire); Resistance 131 and resistance 132 are equivalent to resistance R ₁₅and resistance R ₁₆, its resistance is R ₂, be-k of its sensitivity coefficient _g, so the two resistance value while being affixed on ground wire 23 is R ₂-k _gi.

The voltage output end of observation circuit is gathered and is analyzed by the collecting device of rear end, thereby calculate voltage, electric current, current in resistance property, capacity current, substitutional resistance, equivalent capacitance and the Dielectric loss tangent of capacitive apparatus 2, by the signal is far passed, to transformer station's on-line monitoring center ，Wei transformer station, provide real-time status information of equipment and fault pre-alarming simultaneously.

Computing method below by the parameters of derivation of equation capacitive apparatus 2.

The output voltage u=Usin ω t that makes capacitive apparatus, the current i of capacitive apparatus is:

$i=\frac{u}{R_{\mathrm{DUT}}}+C_{\mathrm{DUT}}\frac{\mathrm{du}}{\mathrm{dt}}=\frac{U\sin \mathrm{\ωt}}{R_{\mathrm{DUT}}}+\mathrm{\ω}{C}_{\mathrm{DUT}}U\cos \mathrm{\ωt}---\left(10\right)$

And the output voltage u of observation circuit _out(voltages between B, C two ends) are:

$\begin{array}{c}{u}_{\mathrm{out}}=u\·\frac{R_1+2k_{G}i}{R_1+2R_2}\\ =\frac{R_1}{R_1+2R_2}U\sin \mathrm{\ωt}+\frac{2k_G}{R_1+2R_2}U\sin \mathrm{\ωt}+(\frac{U\sin \mathrm{\ωt}}{R_{\mathrm{DUT}}}+\mathrm{\ω}{C}_{\mathrm{DUT}}U\cos \mathrm{\ωt})\\ =\frac{R_1}{R_1+2R_2}U\sin \mathrm{\ωt}+\frac{2k_G{U}^2}{R_1+2R_2}\frac{1}{R_{\mathrm{DUT}}}{\sin }^2\mathrm{\ωt}+\frac{{2k}_G{U}^2}{R_1+2R_2}\mathrm{\ω}{C}_{\mathrm{DUT}}\sin \mathrm{\ω}t\cos \mathrm{\ωt}\\ =\frac{k_G{U}^2}{(R_1+2R_2)R_{\mathrm{DUT}}}+\frac{R_{1}U}{R_1+2R_2}\sin \mathrm{\ωt}+\frac{k_G{U}^2\sqrt{1+{\mathrm{\ω}}^2{R}_{\mathrm{DUT}}^2{C}_{\mathrm{DUT}}^2}}{(R_1+2R_2)R_{\mathrm{DUT}}}\sin (2\mathrm{\ωt}-\arctan \frac{1}{\mathrm{\ω}{R}_{\mathrm{DUT}}{C}_{\mathrm{DUT}}})\end{array}---\left(11\right)$

Wherein u is A terminal voltage value, the voltage that U is capacitive apparatus, R _dUTfor the resistance of capacitive apparatus substitutional resistance, C _dUTcapacitance for capacitive apparatus equivalent capacitance.

The output voltage of observation circuit comprises three frequency components as seen from formula (2): DC component, fundamental component and 2 harmonics.

By the output voltage of observation circuit is carried out to signal spectral analysis, the DC component that extracts signal (makes as A ₀), fundamental component (A ₁), 2 harmonic (A ₂) and the phase differential θ of fundamental component and 2 harmonics.According to above-mentioned amount, can instead release voltage, electric current, current in resistance property, capacity current, substitutional resistance, equivalent capacitance and the Dielectric loss tangent that calculates capacitive apparatus, computing method are as follows:

The voltage U of capacitive apparatus is:

$U=(1+\frac{2R_2}{R_1})A_1---\left(12\right)$

The electric current I of capacitive apparatus is:

$I=\frac{R_1{A}_1{A}_2}{k_G}---\left(13\right)$

The substitutional resistance R of capacitive apparatus _dUTfor:

$R_{\mathrm{DUT}}=\frac{R_1+2R_2}{k_G{U}^2}{A}_0---\left(14\right)$

The equivalent capacitance C of capacitive apparatus _dUTfor:

$C_{\mathrm{DUT}}=\frac{\sqrt{{\left(\frac{A_2}{A_0}\right)}^2-1}}{\mathrm{\ω}{R}_{\mathrm{DUT}}}---\left(15\right)$

The current in resistance property I of capacitive apparatus _rfor:

$I_R=\frac{U}{R_{\mathrm{DUT}}}---\left(16\right)$

The capacity current I of capacitive apparatus _cfor:

I _C=ωC _DUTU （17）

The Dielectric loss tangent tan δ of capacitive apparatus is:

t _anδ=t _anθ （18）

Due to the information that the output signal of described observation circuit contains redundancy, above-mentioned computing method are a kind of method more easily wherein just, but is not limited only to above-mentioned computing method, by many algorithms comparison, can improve the accuracy of measurement.

Above-listed detailed description is for the illustrating of possible embodiments of the present invention, and this embodiment is not in order to limit the scope of the invention, and the equivalence that all the present invention of disengaging do is implemented or change, all should be contained in the protection domain of this case.

Claims (5)

1. the capacitive apparatus on-Line Monitor Device based on anisotropic magnetic conducting bridge, it is characterized in that, it comprises observation circuit (1) and capacitive apparatus (2), the input end of described observation circuit (1) is labeled as A end, two output terminal is labeled as respectively B end and C end, its earth terminal is labeled as D end, described observation circuit (1) comprises the first resistance (111), the second resistance (112), the 3rd resistance (121), the 4th resistance (122), the 5th resistance (131) and the 6th resistance (132), wherein, described A end is connected with the output terminal of capacitive apparatus (2), after the first resistance (112) and the 3rd resistance (121) serial connection, be connected between A end and C end, the 6th resistance (132) is connected between side a and b, the 5th resistance (131) is connected between C end and D end, after the second resistance (112) and the 4th resistance (122) serial connection, be connected between B end and D end, described the first resistance (111) is the fixed resistance that resistance is identical (11) with the second resistance (112), the first different in nature magneto-resistor (12) that described the 3rd resistance (121) and the 4th resistance (122) equate for null field resistivity, the second different in nature magneto-resistor (13) that described the 5th resistance (131) and the 6th resistance (132) equate for null field resistivity.

2. the capacitive apparatus on-Line Monitor Device based on anisotropic magnetic conducting bridge according to claim 1, it is characterized in that, described capacitive apparatus (2) is equivalent to equivalent capacitance (21) and the substitutional resistance (22) being in parallel, one end after parallel connection is connected with A end, and the other end is connected with ground wire (23).

3. the capacitive apparatus on-Line Monitor Device based on anisotropic magnetic conducting bridge according to claim 2, is characterized in that, described observation circuit (1) adopts MEMS technique to be integrated on a chip.

4. according to the capacitive apparatus on-Line Monitor Device based on anisotropic magnetic conducting bridge described in claim 2 or 3, it is characterized in that, described observation circuit (1) is close on ground wire (23).

5. the capacitive apparatus on-Line Monitor Device based on anisotropic magnetic conducting bridge according to claim 1, it is characterized in that, the null field resistivity of described the first different in nature magneto-resistor (13) and the second different in nature magneto-resistor (14) all equates, and the absolute value of the sensitivity coefficient of the two is identical, wherein, the sensitivity coefficient of the first different in nature magneto-resistor (13) is for just, and the sensitivity coefficient of described the second different in nature magneto-resistor (14) is for negative.

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