CN111366761A - Sampling device capable of eliminating leakage current - Google Patents

Sampling device capable of eliminating leakage current Download PDF

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Publication number
CN111366761A
CN111366761A CN201811590561.6A CN201811590561A CN111366761A CN 111366761 A CN111366761 A CN 111366761A CN 201811590561 A CN201811590561 A CN 201811590561A CN 111366761 A CN111366761 A CN 111366761A
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China
Prior art keywords
winding
terminal
current
sampling
secondary winding
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CN201811590561.6A
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Chinese (zh)
Inventor
靳绍平
李敏
吴宇
胡琛
毛永晶
周春芽
唐新宇
李欣
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Ganxi Power Supply Branch Of Jiangxi Electric Power Co ltd
State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Jiangxi Electric Power Co Ltd
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Ganxi Power Supply Branch Of Jiangxi Electric Power Co ltd
State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Jiangxi Electric Power Co Ltd
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Priority to CN201811590561.6A priority Critical patent/CN111366761A/en
Publication of CN111366761A publication Critical patent/CN111366761A/en
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    • G—PHYSICS
    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R11/00—Electromechanical arrangements for measuring time integral of electric power or current, e.g. of consumption
    • G01R11/02—Constructional details
    • G01R11/06—Magnetic circuits of induction meters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R22/00—Arrangements for measuring time integral of electric power or current, e.g. electricity meters
    • G01R22/06—Arrangements for measuring time integral of electric power or current, e.g. electricity meters by electronic methods
    • G01R22/10—Arrangements for measuring time integral of electric power or current, e.g. electricity meters by electronic methods using digital techniques

Abstract

The invention discloses a sampling device capable of eliminating leakage current, which comprises a current converter, wherein the current converter comprises converter arms, each arm comprises a main switching element, and the main switching element of each arm can be switched into and out of a circuit between a corresponding DC terminal and an AC terminal so as to control the form of AC voltage at the AC terminal; the system comprises a double-secondary winding two-stage voltage transformer, two A/D sampling circuits, a wireless communication device II, a direct-current power supply and a microprocessor II; the direct current power supply supplies power to the wireless communication equipment II, the microprocessor II and the two A/D sampling circuits; double secondary winding two-stage voltage transformer A0Terminal, ALTerminal, 2n and current transducerP of1End connection; input end V of A/D sampling circuit IINThe input end V of the A/D sampling circuit II is connected with the 2a end of the double-secondary winding double-stage voltage transformerINU with current converteriAnd end connection. The invention achieves the purpose of eliminating leakage current and simultaneously meets the requirements of high-voltage equipotential sampling and low-voltage potential direct measurement.

Description

Sampling device capable of eliminating leakage current
Technical Field
The invention relates to a sampling device capable of eliminating leakage current, and belongs to the technical field of electrical measurement.
Background
The sampling of the high-voltage electric energy metering device relates to the accurate measurement of current and voltage values under the high-voltage state, the conventional measurement method is to convert primary high voltage and large current into secondary voltage and current which are convenient to measure by a mutual inductor in proportion (as shown in figure 1), because a primary winding and a secondary winding of the current mutual inductor are insulated and uniformly wound on the same magnetic core and the insulation quality is the same, a certain distributed capacitance and leakage reactance exist between the primary winding and the secondary winding according to the electrician principle, when operating voltage is applied between the primary winding and the secondary winding, leakage current is generated and superposed with the secondary current of the current mutual inductor, so that the measurement of the current under the high-voltage state generates additional errors, and the measurement of the high-voltage electric energy is inaccurate.
Disclosure of Invention
The invention aims to provide a sampling device capable of eliminating leakage current so as to eliminate the influence of the leakage current and achieve the purpose of wide-range measurement.
The invention (1) adopts a secondary current equipotential sampling method to force a secondary loop and a primary loop of a current proportional converter to have equal potential, and the voltage difference between the primary loop and the secondary loop of the current proportional converter is zero, so as to achieve the purpose of eliminating leakage current; (2) the equipotential method of the secondary voltage sampling circuit and the current sampling circuit is adopted, so that the requirement that the current and voltage values must be synchronously sampled when the electric energy is measured at high precision is met; (3) in order to adapt to the measurement of current, voltage high voltage equipotential, adopt the double secondary winding double-stage voltage transformer to replace the ordinary voltage transformer, the ordinary voltage transformer has only one secondary winding, the invention is on the basis of keeping a primary secondary winding originally, increase two secondary windings taking primary voltage as reference potential;
the sampling device capable of eliminating leakage current comprises a current converter (201), wherein the current converter (201) comprises converter arms, each arm comprises a main switching element, and the main switching element of each arm can be switched into and out of a circuit between a corresponding DC terminal and an AC terminal to control the form of an AC voltage at the AC terminal; the system comprises a double-secondary winding two-stage voltage transformer, two A/D sampling circuits, a wireless communication device II, a direct-current power supply and a microprocessor II; the direct current power supply supplies power to the wireless communication equipment II, the microprocessor II and the two A/D sampling circuits; double secondary winding two-stage voltage transformer A0Terminal, ALTerminal, 2n and P of current transformer1X of end-connected, double-secondary winding two-stage voltage transformer0Terminal and XLEnd connection; input end V of A/D sampling circuit IINThe input end V of the A/D sampling circuit II is connected with the 2a end of the double-secondary winding double-stage voltage transformerINAnd current converterU of (1)iThe common terminal com of the A/D sampling circuit I and the A/D sampling circuit II, and the grounding ends GND of the wireless communication equipment II, the direct current power supply and the microprocessor are connected to the P of the current converter1The end is equipotential with the primary voltage of the integral testing device of the electric energy metering device; and the microprocessor II controls the A/D sampling circuit I and the A/D sampling circuit II, and is connected with the wireless communication equipment II.
The invention has the advantages that the primary circuit and the secondary circuit are equipotential current proportion converters, so that the potential difference of the primary circuit to the secondary circuit is zero, and the aim of eliminating leakage current is fulfilled. Because the potential difference of the primary loop to the secondary loop is zero, the insulation structure of the current proportional converter is simple, the application of the wide-range zero-flux current transformer is convenient, the rated secondary current is designed to be 0.1A, the increase of the turn ratio is favorable for improving the accuracy of the transformer, the program control automatic switching of the current range can be realized, and meanwhile, the sectional areas of the magnetic core and the secondary winding wire are reduced, so that the current proportional converter has the advantages of small volume, light weight, low manufacturing cost, convenience in integration and the like; the double-secondary winding two-stage voltage transformer is adopted, and the requirements of high-voltage equipotential sampling and low-voltage potential direct measurement are met simultaneously.
Drawings
FIG. 1 is a schematic diagram of a sampling apparatus capable of eliminating leakage current;
fig. 2 is a schematic diagram of a current transducer.
The symbols in the figure are as follows:
TVG-is a double secondary winding double stage voltage transformer;
A0、X0a primary winding N of a two-stage voltage transformer with two secondary windings1A high potential terminal and a low potential terminal;
AL、XL-two-stage voltage transformer excitation windings N with double secondary windings respectivelyLA high potential terminal and a low potential terminal;
1a and 1N-are secondary windings N of a double-secondary-winding two-stage voltage transformer respectively2The non-polar end and the polar end of (1);
2a, 2n- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Is a secondary winding N of a double-secondary winding two-stage voltage transformer3The non-polar end and the polar end of (1);
I1-is a primary current;
P1、P2the primary winding polarity end and the non-polarity end of the current transformer are respectively represented as-a-and-b-;
W1-is a primary winding of a current transformer;
W2-is a current transformer secondary proportional winding;
WT-a secondary detection winding for the current transformer;
1. 2- - -two annular iron cores of the current transformer are respectively arranged;
J01、J02、J03、J04、J05-the secondary proportional winding range switching relay contacts of the wide-range zero-flux current transformer are respectively;
S1-is a wide-range zero-flux current transformer secondary winding polarity end;
S2、S3、S4、S5、S6-is a wide-range non-polar end of each range of the secondary winding of the zero-flux current transformer;
T1、T2the secondary magnetic balance detection winding polarity end and the non-polarity end of the wide-range zero-flux current transformer are respectively arranged;
Ui-is the output voltage terminal of the current transformer;
r < - > -is a secondary current sampling resistor of the current converter;
VIN-is analog input end of analog-to-digital conversion integrated circuit;
com- -is a common end;
data bus-is a data bus;
GND-is a common terminal;
V+-is a dc power supply;
Vcc-is an input terminal of an operating power supply of the integrated circuit;
Detailed Description
The following describes the steps of the present invention with reference to the accompanying drawings.
A sampling device for eliminating leakage current as shown in figure 1, comprising a current converter (201), said current converter (201) comprising converter limbs, each limb portion comprising a main switching element, the main switching element of each limb portion being switchable to switch the corresponding limb portion into and out of circuit between the corresponding DC terminal and the AC terminal to control the form of the AC voltage at the AC terminal; the system comprises a double-secondary winding two-stage voltage transformer (202), two A/D sampling circuits, a wireless communication device II (205), a direct current power supply (206) and a microprocessor II (207); the direct current power supply (206) supplies power to the wireless communication equipment II (205), the microprocessor II (207) and the two A/D sampling circuits; a of double secondary winding two-stage voltage transformer (202)0Terminal, ALTerminal, 2n and P of current transformer (201)1X of end-connected, dual secondary winding, two-stage voltage transformer (202)0Terminal and XLEnd connection; input terminal V of A/D sampling circuit I (203)INThe input end V of the A/D sampling circuit II (204) is connected with the 2a end of the double-secondary winding two-stage voltage transformer (202)INU with current converter (201)iThe common terminal com of the A/D sampling circuit I (203) and the A/D sampling circuit II (204) and the grounding terminals GND of the wireless communication equipment II (205), the direct current power supply (206) and the microprocessor (207) are connected to P of the current converter (201)1The end is equipotential with the primary voltage of the integral testing device of the electric energy metering device; and the microprocessor II (207) controls the A/D sampling circuit I (203) and the A/D sampling circuit II (204) to carry out synchronous sampling and data storage on the current and voltage signals after the proportional conversion, and respectively calculates a current effective value, a voltage effective value, active power, reactive power, electric energy and a phase position, wherein the calculation method comprises the following steps:
calculating the effective value of the voltage:
Figure BDA0001920144920000041
Figure BDA0001920144920000042
calculating the effective value of the current:
Figure BDA0001920144920000043
the derivation is referred to electric energy metering skill assessment training teaching materials, China Power Press, Chen Suo Shu Suo, P139-P140; calculating the average active power in one period:
Figure BDA0001920144920000044
calculating the active electric energy in one period:
Figure BDA0001920144920000045
the derivation is referred to electric energy metering skill assessment training teaching materials, China Power Press, Chen Suo Shu, P97-P98;
calculating the average reactive power in one period:
Figure BDA0001920144920000046
reactive power calculation in one period:
Figure BDA0001920144920000051
for derivation, see "teaching materials for assessment and training of skills in electric energy metering, electric power publishing in China, Chen Suo Shu, P133 Power factor calculation:
Figure BDA0001920144920000052
for derivation, see "teaching materials for assessment and training of skills in electric energy metering," electric power publishing house, Chen Dynasty, and P135 formulas (1) to (8): t-sine wave cycle time;
n is the number of samples in a period;
u is voltage effective value;
i is the effective value of current;
p is the average active power in one period;
q-average reactive power over a period;
phi-phase
I(tk) At tkA current transient at a time;
U(tk) At tkA voltage instantaneous value of a time;
Δ t-sampling time interval;
Figure BDA0001920144920000053
-lag tkA current transient of one quarter cycle at a time;
the current transformer (201) is shown in fig. 2. Comprises a zero-flux current transformer, a current/voltage conversion sampling resistor, a magnetic balance detection and drive circuit, and five proportional winding range switching relays J01、J02、J03、J04、J05. Primary winding W1A through-core one turn, which can be replaced by a primary current lead in specific implementation; w2Is a secondary proportional winding with a tap S2、S3、S4、S5、S6The current measuring ranges are respectively corresponding to 1A, 5A, 20A, 100A and 500A; wTA magnetic balance detection winding. The logical relationship between the current range and the relay contact (see table 1); wTT of winding1Signal input end S of magnetic balance circuiti，WTT of winding2A com end is connected; w2S of the winding1Is connected with the output end Ui，W2S of the winding2、S3、S4、S5、S6J with terminals connected to relays respectively01、J02、J03、J04、J05Opening and closing contact, relay J01～J05Fixed contact magnetic balance detectionAnd a current output terminal I of the drive circuit0(ii) a The current sampling resistor R is connected in series with S1And the common end com end. The com of the magnetic balance detection and drive circuit is connected with the com of the public end. The magnetic balance detection winding is uniformly wound on the annular iron core I1, the annular iron core II 2 is embedded inside the annular iron core I1, and the proportional winding is uniformly wound on the annular iron core I1 and the annular iron core II 2. And the primary winding is also uniformly wound on the annular iron core I1 and the annular iron core II 2.
TABLE 1
Figure BDA0001920144920000061
Note that in the table, "√" indicates a contact is closed and "×" indicates a contact is open.
And (3) calculating the number of winding turns:
according to the basic principle of current transformer, the product of primary current and the number of turns of primary winding is equal to the product of secondary current and the number of turns of secondary winding, that is:
I1W1＝I2W2……………(9)
in the formula:
I1、I2primary current and secondary current respectively;
W1、W2the number of turns of the primary winding and the number of turns of the secondary winding are respectively;
due to W1Is 1 turn, I2When the ratio is 0.1A:
Figure BDA0001920144920000062
each range secondary winding is formed by connecting segmented winding coils in series, and the number of turns of each segment of winding is shown in a table 2:
TABLE 2
Figure BDA0001920144920000063
Figure BDA0001920144920000071
Referring to fig. 1, the double-secondary winding two-stage voltage transformer includes a first stage core, a second stage core, and an excitation winding NLWound on the first-stage iron core and having a primary winding N1And a secondary winding N2Secondary winding N3Wound on the first and second iron cores, and an excitation winding NLHigh potential terminal A ofLAnd a primary winding N1High potential terminal A of0Connecting, exciting windings NLLow potential terminal X ofLAnd a primary winding N1Low potential terminal X of0Connecting; secondary winding N32N and the primary winding N1High potential terminal A of0Connecting, secondary winding N3Is arranged at the primary winding N1High potential terminal A of0One side. Secondary winding N3Non-polar terminal 2a and primary winding N1Low potential terminal X of0Should not be less than the primary winding N1High potential terminal A of0And a primary winding N1Low potential terminal X of0The distance of (c). Secondary winding N3Non-polar terminal 2a and primary winding N1High potential terminal A of0The insulation distance between the two should be not less than 2 mm. Self primary winding N1High potential terminal A of0Lead-out A0Terminal, self primary winding N1Low potential terminal X of0Lead out X0Terminal, self-secondary winding N2The non-polar end 1a of the secondary winding is led out to form an end 1a21N from the secondary winding N3The non-polar end 2a of (2) leads out the end 2 a.
The sampling device capable of eliminating leakage current comprises the following manufacturing steps:
(1) constructing a current converter (201), a primary winding W1The core is penetrated by one turn, and the core can be replaced by a primary high-current lead in specific implementation; w2Is a secondary proportional winding with a tap S2、S3、S4、S5、S6The current measuring device respectively corresponds to five current measuring ranges of 1A, 5A, 20A, 100A and 500A, and the rated secondary current is 0.1A; wTFor detecting magnetic equilibriumAnd (4) grouping. The logical relationship between the current range and the relay contact is shown in table 1; wTT of winding1Signal input terminal S connected with magnetic balance detection and drive circuiti，WTT of winding2A com end connected with the magnetic balance detection and drive circuit; w2S of the winding1Is connected with the output end Ui，W2S of the winding2、S3、S4、S5、S6J with terminals connected to relays respectively01、J02、J03、J04、J05Opening and closing contact, relay J01～J05The fixed contact is connected with the current output end I of the magnetic balance detection and drive circuit0(ii) a The current sampling resistor R is connected in series with S1And com terminal. The com of the magnetic balance detection and drive circuit is connected with the common end com, wherein, the magnetic balance detection winding is uniformly wound on the annular iron core 1, then the annular iron core 2 is embedded inside the annular iron core 1, and then the proportional winding is uniformly wound on the annular iron core 1 and the annular iron core 2. The primary winding is also uniformly wound on the annular iron core 1 and the annular iron core 2.
(2) Constructing a current and voltage proportional conversion and sampling unit: a of double secondary winding two-stage voltage transformer (202)0Terminal, ALTerminal, 2n and P of current transformer (201)1X of end-connected, dual secondary winding, two-stage voltage transformer (202)0Terminal and XLEnd connection; input terminal V of A/D sampling circuit I (203)INThe input end V of the A/D sampling circuit II (204) is connected with the 2a end of the double-secondary winding two-stage voltage transformer (202)INU with current converter (201)iThe common terminal com of the A/D sampling circuit I (203) and the A/D sampling circuit II (204) and the grounding terminals GND of the wireless communication equipment II (205), the direct current power supply (206) and the microprocessor II (207) are connected to P of the current converter (201)1And the end is equipotential with the primary voltage of the integral testing device of the electric energy metering device.
Those skilled in the art will appreciate that the invention may be practiced without these specific details.

Claims (6)

1. Can eliminate hourglassThe sampling device of electric current, its characterized in that: comprising a current converter (201), the current converter (201) comprising converter limbs, each limb portion comprising a main switching element, the main switching element of each limb portion being switchable to switch the respective limb portion into and out of circuit between the respective DC and AC terminals to control the profile of the AC voltage at the AC terminals; the system comprises a double-secondary winding two-stage voltage transformer (202), a wireless communication device II (205), a direct current power supply (206) and a microprocessor II (207); the direct current power supply (206) supplies power to the wireless communication equipment II (205) and the microprocessor II (207); a of double secondary winding two-stage voltage transformer (202)0Terminal, ALTerminal, 2n and P of current transformer (201)1X of end-connected, dual secondary winding, two-stage voltage transformer (202)0Terminal and XLEnd connection; input terminal V of A/D sampling circuit I (203)INThe input end V of the A/D sampling circuit II (204) is connected with the 2a end of the double-secondary winding two-stage voltage transformer (202)INU with current converter (201)iThe common terminal com of the A/D sampling circuit I (203) and the A/D sampling circuit II (204) and the grounding terminals GND of the wireless communication equipment II (205), the power supply (206) and the microprocessor (207) are connected to P of the converter (201)1A terminal; and the microprocessor II (207) controls the A/D sampling circuit I (203) and the A/D sampling circuit II (204), and the microprocessor II (207) is connected with the wireless communication equipment II (205).
2. The sampling device of claim 1, wherein the sampling device is characterized in that: the current proportional converter (201) comprises a zero-flux current transformer, a current/voltage conversion sampling resistor, a magnetic balance detection and drive circuit and five proportional winding range switching relays J01、J02、J03、J04、J05Primary winding W1Secondary proportional winding W2Magnetic balance detection winding WT(ii) a Magnetic balance detection winding WTT of1Signal input terminal S connected with magnetic balance detection and drive circuitiMagnetic balance detecting winding WTT of2The com end of the end connection driving circuit; second order proportionWinding W2Polar terminal S of1Is connected with the output end UiSecond order proportional winding W2S of2、S3、S4、S5、S6J with terminals connected to relays respectively01、J02、J03、J04、J05Opening and closing contact, relay J01～J05The fixed contact is connected with the current output end I of the magnetic balance detection and drive circuito(ii) a The current sampling resistor R is connected in series with S1And com terminal; the com of the magnetic balance detection and drive circuit is connected with the com of the public end.
3. The sampling device of claim 2, wherein the sampling device is characterized in that: the magnetic balance detection winding is uniformly wound on the annular iron core I (1), the annular iron core II (2) is embedded inside the annular iron core I (1), and the proportion winding is uniformly wound on the annular iron core I (1) and the annular iron core II (2). The primary winding is also uniformly wound on the annular iron core I (1) and the annular iron core II (2).
4. The sampling device of claim 1, wherein the sampling device is characterized in that: the double-secondary winding two-stage voltage transformer comprises a first-stage iron core, a second-stage iron core and an excitation winding NLWound on the first-stage iron core and having a primary winding N1And a secondary winding N2Secondary winding N3Wound on the first and second iron cores, and an excitation winding NLHigh potential terminal A ofLAnd a primary winding N1High potential terminal A of0Connecting, exciting windings NLLow potential terminal X ofLAnd a primary winding N1Low potential terminal X of0Connecting; secondary winding N32N and the primary winding N1High potential terminal A of0Connecting, secondary winding N3Is arranged at the primary winding N1High potential terminal A of0One side.
5. The sampling device of claim 4, which can eliminate leakage currentIs characterized in that: secondary winding N3Non-polar terminal 2a and primary winding N1Low potential terminal X of0Should not be less than the primary winding N1High potential terminal A of0And a primary winding N1Low potential terminal X of0The distance of (c).
6. The sampling device of claim 4, wherein the sampling device is characterized in that: self primary winding N1High potential terminal A of0Lead-out A0Terminal, self primary winding N1Low potential terminal X of0Lead out X0Terminal, self-secondary winding N2The non-polar end 1a of the secondary winding is led out to form an end 1a21N from the secondary winding N3The non-polar end 2a of (2) leads out the end 2 a.
CN201811590561.6A 2018-12-25 2018-12-25 Sampling device capable of eliminating leakage current Pending CN111366761A (en)

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