CN114487919B - Self-adaptive method for wiring mode of three-phase electric energy meter - Google Patents

Self-adaptive method for wiring mode of three-phase electric energy meter Download PDF

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CN114487919B
CN114487919B CN202210392319.8A CN202210392319A CN114487919B CN 114487919 B CN114487919 B CN 114487919B CN 202210392319 A CN202210392319 A CN 202210392319A CN 114487919 B CN114487919 B CN 114487919B
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electric energy
phase
energy meter
unit
control unit
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CN114487919A (en
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王世勇
李峥
董聪
张权
孙天运
张磊
李涛
李席
李义真
李伟克
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Shijiazhuang Kelin Electric Co Ltd
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Shijiazhuang Kelin Electric Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/55—Testing for incorrect line connections
    • 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
    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
    • G01R35/04—Testing or calibrating of apparatus covered by the other groups of this subclass of instruments for measuring time integral of power or current
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
    • G05B19/042—Programme control other than numerical control, i.e. in sequence controllers or logic controllers using digital processors
    • G05B19/0423—Input/output

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Abstract

The utility model provides a self-adaptation method of three-phase electric energy meter mode of connection, belongs to electric energy meter terminal technical field, the electric energy meter includes MCU the control unit, with the help of the analog data acquisition unit that measurement processing unit and MCU the control unit are connected, with the help of the switching power supply unit that power management unit and MCU the control unit are connected and the liquid crystal display unit, memory cell, communication unit, button unit, load control unit and the reference voltage ground switch control unit that MCU the control unit is connected, the self-adaptation method includes adopts triangle-shaped method and slope method to judge three-phase electric energy meter mode of connection. The wiring mode of the electric energy meter can realize the self-adaptation of three phases, three phases and four lines.

Description

Self-adaptive method for wiring mode of three-phase electric energy meter
Technical Field
The invention belongs to the technical field of electric energy meter terminals, and particularly relates to a self-adaptive method for a three-phase electric energy meter wiring mode.
Background
At present, electric energy meters with various voltage specifications exist in the market, for example, domestic three-phase electric energy meters have three-phase four-wire 3 x 220/380V electric energy meters, 3 x 57.7/100V electric energy meters and three-phase three-wire 3 x 100V electric energy meters, and foreign countries have certain differences in voltage according to different regions. Therefore, when the demander has different specification requirements to the three-phase electric energy meter, often can cause very big puzzlement to the producer, for the three-phase electric energy meter demand that satisfies different specifications, need be equipped with the material and many production lines of various specifications in the aspect of the production, very easily cause the waste and the storage confusion in place, be unfavorable for the production management of company and the promotion of production efficiency, can cause the waste of resource even.
Disclosure of Invention
The invention aims to solve the technical problem of providing a self-adaptive method of the wiring mode of a three-phase electric energy meter, which improves the automatic judgment algorithm of the wiring mode of the electric energy meter to enable the three-phase electric energy meter to automatically adapt to the wiring mode of three-phase three-wire or three-phase four-wire, so that the metering parameters of the three-phase electric energy meter do not need to be corrected again after the initialization operation, and the utilization rate of the three-phase electric energy meter is further improved.
The technical scheme adopted by the invention is as follows: a self-adaptive method for a three-phase electric energy meter in a wiring mode comprises an MCU control unit, an analog data acquisition unit connected with the MCU control unit by means of a metering processing unit, a switching power supply unit connected with the MCU control unit by means of a power supply management unit, a liquid crystal display unit, a storage unit, a communication unit, a key unit, a load control unit and a reference voltage ground switching control unit, wherein the liquid crystal display unit, the storage unit, the communication unit, the key unit, the load control unit and the reference voltage ground switching control unit are connected with the MCU control unit, and the self-adaptive method comprises the following steps:
step 1, the analog data acquisition unit carries out wave motion on the three-phase line voltage according to the frequency fShape collection, data reading is carried out after more than two cycles, and waveform data points on one cycle are respectively recorded as a set
Figure DEST_PATH_IMAGE001
、
Figure DEST_PATH_IMAGE002
、
Figure DEST_PATH_IMAGE003
W is the data number of one cycle;
collection
Figure DEST_PATH_IMAGE004
、
Figure DEST_PATH_IMAGE005
、
Figure DEST_PATH_IMAGE006
Calculating by means of a line voltage effective value formula, and respectively recording the calculation results as Uab、Ubc、Uca；
Meanwhile, the metering processing unit also collects and processes three-phase voltage, and reads the processed data as a three-phase voltage effective value Uan、Ubn、Ucn；
Step 2, U in effective value of line voltageab、UbcAnd UcaIf the sum of any two is larger than the sum of any two and the third party, executing the step 3, otherwise, returning to the step 1;
step 3, utilizing the effective value U of the line voltageab、Ubc、UcaDrawing a triangle, and calculating the radius L of a circumscribed circle of the triangle;
step 4, the radius L of the circumscribed circle is respectively equal to the effective value U of the phase voltagean、Ubn、UcnComparing, if at least one data is not equal, judging that the wiring mode of the electric energy meter is a three-phase four-wire mode, and executing the step 5; otherwise, executing step 6;
step 5, judging Uan、Ubn、UcnWhether the zero line is equal to the zero line is judged, if so, the zero line is not accessed in the three-phase four-wire connection mode of the electric energy meter, and an alarm is given; if the three phases are not equal to each other, judging that the three-phase four-wire connection mode of the electric energy meter is correct;
step 6, respectively finding out the sets by adopting a traversal method
Figure 900189DEST_PATH_IMAGE004
、
Figure 82908DEST_PATH_IMAGE005
、
Figure 209783DEST_PATH_IMAGE006
Two adjacent points of upper zero crossing, pair set
Figure 73834DEST_PATH_IMAGE004
、
Figure 216102DEST_PATH_IMAGE005
、
Figure 507406DEST_PATH_IMAGE006
Two adjacent points of middle zero crossing are respectively connected and the respective connection slope is calculated, and then the calculation result of the respective connection slope is recorded as Ka、Kb、Kc；
Step 7, judging Ka、Kb、KcWhether the two phases are equal or not is judged, and if the two phases are equal, the wiring mode of the electric energy meter is judged to be a three-phase four-wire mode; if not, executing step 8;
step 8, judging Ka、KcWhether the two phases are equal or not is judged, if so, the wiring mode of the electric energy meter is judged to be a three-phase three-wire mode; if the difference is not equal, the wiring mode is judged to be wrong, and an alarm is given.
Further, aggregating in step 1
Figure 40019DEST_PATH_IMAGE004
、
Figure 317547DEST_PATH_IMAGE005
、
Figure 455268DEST_PATH_IMAGE006
The effective value of the line voltage is calculated by the following formula:
Figure DEST_PATH_IMAGE007
；
Figure DEST_PATH_IMAGE008
；
Figure DEST_PATH_IMAGE009
；
wherein R is1—RWTaken from the collection
Figure 855156DEST_PATH_IMAGE001
Sampling points of (1); t is1—TWTaken from the collection
Figure 875065DEST_PATH_IMAGE002
Sampling points of (1); p1—PWTaken from the collection
Figure 815339DEST_PATH_IMAGE003
The sampling points of (a).
Further, the phase voltage U in the three-phase four-wire connection mode in step 5 and step 7 is appliedan、Ubn、UcnAnd judging that the voltage of the electric energy meter is 3 × 220/380V if one of the three voltages is more than 70V, and judging that the voltage of the electric energy meter is 3 × 57.7/100V if none of the three voltages is more than 70V.
Further, the reference voltage and the ground are switched for the electric energy meter in the three-phase three-wire connection mode in the step 8, and the method is that the MCU control unit controls the reference voltage and the ground switching control unit to switch the power supply ground wire from the U ground wirenSwitch to Ub。
Further, the method for drawing the triangle and calculating the radius L of the circumscribed circle in step 3 includes:
taking F (0,0) point as a starting point in a coordinate system and taking a line voltage effective value UabIs positioned on the X axis by the value of G (U)ab0) point, then the effective value U of the line voltage is calculatedbc、UcaThe value of (d) is connected as the other two sides of the triangle, and the connection point is H (x)1,y1) Point;
secondly, utilizing a coordinate formula:
Figure DEST_PATH_IMAGE010
，
calculating coordinates of the point H;
with the three-point coordinates of F, G, H known, from the triangle's eccentric characteristics and the system of equations:
Figure DEST_PATH_IMAGE011
；
calculating coordinates of the triangle outer center N' (a, b);
and fourthly, according to the coordinate of the outer center N 'of the triangle (a, b), calculating the radius L of the circumscribed circle, namely the distances from the F point, the G point and the H point to the N' point respectively.
Further, in step 6, the sets are combined
Figure 666620DEST_PATH_IMAGE004
、
Figure 175093DEST_PATH_IMAGE005
、
Figure 885560DEST_PATH_IMAGE006
Two adjacent points of the middle zero crossing are respectively connected and the respective connection slope is calculated, and the respective connection slope calculation method comprises the following steps:
step I. set
Figure 426263DEST_PATH_IMAGE004
Two adjacent points of middle zero crossing are Rj (x j, y j)、Rj+1(x j+1,y j+1)；
According to the formula of the slope of the line, Rj (x j, y j)、Rj+1(x j+1,y j+1) The slope calculation formula of the connecting line between the two points is as follows:
Figure DEST_PATH_IMAGE012
；
step II. set
Figure 866471DEST_PATH_IMAGE005
、
Figure 467217DEST_PATH_IMAGE006
Referring to step I by a slope calculation formula of a connecting line between two adjacent points of middle zero crossing;
step III. in the set
Figure 537417DEST_PATH_IMAGE004
、
Figure 85073DEST_PATH_IMAGE005
、
Figure 910946DEST_PATH_IMAGE006
The values of two adjacent points of zero crossing are respectively searched and respectively substituted into a slope calculation formula, and the line voltage slope K of the three phases A, B, C can be obtaineda 、Kb、Kc。
The beneficial effects produced by adopting the invention are as follows: by improving the automatic judgment algorithm of the wiring mode of the electric energy meter, the three-phase electric energy meter can automatically adapt to the wiring mode of three-phase three-wire or three-phase four-wire, so that the metering parameters of the three-phase electric energy meter do not need to be corrected again after the initialization operation, and the utilization rate of the three-phase electric energy meter is improved; the three-phase electric energy meter has wide application range and can be applied to various occasions.
Drawings
FIG. 1 is a block diagram of a three-phase electric energy meter;
FIG. 2 is a flow chart of an initialization implementation of the three-phase electric energy meter;
FIG. 3 is a flow chart of the wiring manner determination of the three-phase electric energy meter;
FIG. 4 is a flow chart of the load control determination of the three-phase electric energy meter;
FIG. 5 is a voltage-current wiring diagram of an embodiment example 1 of the three-phase electric energy meter;
FIG. 6 is a voltage-current wiring diagram of an embodiment example 2 of the three-phase electric energy meter;
FIG. 7 is a voltage-current wiring diagram of an embodiment 3 of the three-phase electric energy meter;
fig. 8 is a schematic diagram of the three-phase line voltage of the present invention plotted in triangular form.
Detailed Description
Referring to the attached figures 1-8, the electric energy meter comprises an MCU control unit, an analog data acquisition unit connected with the MCU control unit by a metering processing unit, a switching power supply unit connected with the MCU control unit by a power supply management unit, a liquid crystal display unit, a storage unit, a communication unit, a key unit, a load control unit and a reference voltage ground switching control unit, wherein the liquid crystal display unit, the storage unit, the communication unit, the key unit, the load control unit and the reference voltage ground switching control unit are connected with the MCU control unit.
The three-phase electric energy meter of the invention is shown in a schematic block diagram in fig. 1, and mainly comprises an MCU control unit, a liquid crystal display unit, a communication unit, a storage unit, a key unit, a load control unit, a power management unit, a switching power supply unit, a reference voltage ground switching control unit, a metering processing unit and the like, so that the real-time processing of electric energy data is realized, corresponding instantaneous data processing and event processing are carried out, and the three-phase electric energy meter has the functions of maximum demand calculation, voltage monitoring, load control and data storage display.
The electric energy meter is connected to the electric meter terminal according to a three-phase three-wire or three-phase four-wire connection mode according to a field application environment.
The analog data acquisition unit respectively provides the three-phase voltage analog sampling values to the metering processing unit and an ADC sampling port in the MCU, and the three-phase current analog sampling values are provided to the metering processing unit.
The metering chip in the metering processing unit is a core unit, corresponding metering and measuring processing is carried out on the obtained voltage sampling and current sampling according to the loaded metering mode and metering parameters, instantaneous quantities such as voltage, current, power and the like are obtained through calculation, processing of active electric energy, reactive electric energy and apparent electric energy is carried out, data interaction is carried out on the processed data and the MCU control unit through the SPI, and the MCU control unit carries out operations such as data storage and display, event judgment, load control and the like after obtaining the data.
And the ADC of the MCU control unit samples the line voltage waveform and provides data for judging the previous terminal access mode.
The load control unit is mainly used for prompting the control of a load circuit and the trip after the wiring mode is not judged.
The power management unit mainly supplies power.
The communication unit mainly reads data in 485, carrier, GPRS, infrared modes and the like.
Referring to fig. 5-7, the field-installed wiring scheme of the three-phase electric energy meter of the present invention is fully wired in a corresponding wiring scheme.
The access mode of the embodiment 1 of the three-phase electric energy meter is a three-phase four-wire direct access mode, the connection terminal is connected as shown in fig. 5, the terminal 2, the terminal 5, the terminal 8 and the terminal 10 are respectively accessed to the voltage input ends Ua, Ub, Uc and Un, after three-phase currents of A, B and C flow through the mutual inductor, the secondary side output + end of the mutual inductor is respectively accessed to the terminals 1, 4 and 7, and the output-end is respectively accessed to the terminals 3, 6 and 9, so that the installation of the electric energy meter is realized.
The access mode of the embodiment 2 of the three-phase electric energy meter is that three-phase four wires are accessed through a mutual inductor, a wiring terminal is connected as shown in fig. 6, A, B, C three-phase voltage passes through the mutual inductor, the secondary side output + ends of the mutual inductor are respectively accessed to the terminals 2, 5 and 8, the output-ends are commonly accessed to the terminal 10, A, B, C three-phase current passes through the mutual inductor, the secondary side output + ends of the mutual inductor are respectively accessed to the terminals 1, 4 and 7, and the output-ends are respectively accessed to the terminals 3, 6 and 9, so that the installation of the electric energy meter is realized.
The three-phase electric energy meter embodiment 3 is connected in a manner that a three-phase three-wire is connected through a transformer, a wiring terminal is connected as shown in fig. 7, A, C two-phase voltage passes through the transformer, the secondary side output + ends of the transformer are respectively connected to terminals 2 and 8, the output-ends are commonly connected to terminal 5, A, C two-phase current passes through the transformer, the secondary side output + ends of the transformer are respectively connected to terminals 1 and 7, and the output-ends are respectively connected to terminals 3 and 9, so that the electric energy meter is installed.
The specific form of operation of the electric energy meter of the present invention is illustrated by reference to the logic block diagrams shown in fig. 2 and 3, and thus the adaptive method of the present invention comprises the following steps:
step 1, the analog data acquisition unit carries out waveform acquisition on the voltage of the three-phase line according to the frequency f, data reading is carried out after more than two cycles, and waveform data points on one cycle are respectively recorded as a set
Figure 151435DEST_PATH_IMAGE001
、
Figure 367652DEST_PATH_IMAGE002
、
Figure 594366DEST_PATH_IMAGE003
W is the data number of one cycle;
collection
Figure 150112DEST_PATH_IMAGE004
、
Figure 686135DEST_PATH_IMAGE005
、
Figure 389649DEST_PATH_IMAGE006
Calculating by means of a line voltage effective value formula, and respectively recording the calculation results as Uab、Ubc、Uca；
Meanwhile, the metering processing unit also collects and processes three-phase voltage, and reads the processed data as a three-phase voltage effective value Uan、Ubn、Ucn；
Step 2, U in effective value of line voltageab、UbcAnd UcaIf the sum of any two is larger than the sum of any two and the third party, executing the step 3, otherwise, returning to the step 1;
step 3, utilizing the effective value U of the line voltageab、Ubc、UcaDrawing a triangle, and calculating the radius L of a circumscribed circle of the triangle;
step 4, the radius L of the circumscribed circle is respectively equal to the effective value U of the phase voltagean、Ubn、UcnComparing, if at least one data is not equal, judging that the wiring mode of the electric energy meter is a three-phase four-wire mode, and executing a step 5; otherwise, executing step 6;
step 5, judging Uan、Ubn、UcnWhether the zero line is equal to the zero line is judged, if so, the zero line is not accessed in the three-phase four-wire connection mode of the electric energy meter, and an alarm is given; if the three phases are not equal to each other, judging that the three-phase four-wire connection mode of the electric energy meter is correct;
step 6, respectively finding out the sets by adopting a traversal method
Figure 279108DEST_PATH_IMAGE004
、
Figure 830306DEST_PATH_IMAGE005
、
Figure 412597DEST_PATH_IMAGE006
Two adjacent points of upper zero crossing, pair set
Figure 603407DEST_PATH_IMAGE004
、
Figure 421190DEST_PATH_IMAGE005
、
Figure 685950DEST_PATH_IMAGE006
Two adjacent points of the middle zero crossing are respectively connected and the respective connection slope is calculated, and then the calculation result of the respective connection slope is recorded as Ka、Kb、Kc；
Step 7, judging Ka、Kb、KcWhether the two phases are equal or not is judged, and if the two phases are equal, the wiring mode of the electric energy meter is judged to be a three-phase four-wire mode; if not, executing step 8;
step 8, judging Ka、KcWhether the two phases are equal or not is judged, if so, the wiring mode of the electric energy meter is judged to be a three-phase three-wire mode; if the difference is not equal, the wiring mode is judged to be wrong, and an alarm is given.
Further, aggregating in step 1
Figure 314508DEST_PATH_IMAGE004
、
Figure 992614DEST_PATH_IMAGE005
、
Figure 223875DEST_PATH_IMAGE006
The effective value of the line voltage is calculated by the following formula:
Figure 998933DEST_PATH_IMAGE007
；
Figure 657448DEST_PATH_IMAGE008
；
Figure 822850DEST_PATH_IMAGE009
；
wherein R is1—RWTaken from a collection
Figure 458800DEST_PATH_IMAGE001
Sampling points of (1); t is1—TWTaken from the collection
Figure 229310DEST_PATH_IMAGE002
Sampling points of (1); p1—PWTaken from the collection
Figure 183359DEST_PATH_IMAGE003
The sampling points of (a).
For phase voltage U of three-phase four-wire connection mode in step 5 and step 7an、Ubn、UcnAnd judging that the voltage of the electric energy meter is 3 × 220/380V if one of the three voltages is more than 70V, and judging that the voltage of the electric energy meter is 3 × 57.7/100V if none of the three voltages is more than 70V.
Switching the reference voltage and the reference ground of the electric energy meter in the three-phase three-wire connection mode in the step 8, and controlling the reference voltage and ground switching control unit to switch the power supply ground wire from U through the MCU control unitnSwitch to Ub。
Referring to fig. 8, the method for drawing the triangle and determining the radius L of the circumscribed circle in step 3 includes:
taking F (0,0) point as a starting point in a coordinate system, and taking a line voltage effective value UabIs positioned on the X axis by the value of G (U)ab0) point, then the effective value U of the line voltage is calculatedbc、UcaThe value of (d) is connected as the other two sides of the triangle, and the connection point is H (x)1,y1) Point;
and secondly, utilizing a coordinate formula:
Figure 836057DEST_PATH_IMAGE010
，
calculating coordinates of the point H;
with the known F, G, H three-point coordinates, according to the triangle's eccentric characteristics and the system of equations:
Figure 674700DEST_PATH_IMAGE011
；
calculating coordinates of the triangle outer center N' (a, b);
and fourthly, calculating the radius L of the circumscribed circle, namely the distances from the F point, the G point and the H point to the N 'point respectively according to the obtained coordinates of the triangle outsenter N' (a, b).
Set pair in step 6
Figure 643925DEST_PATH_IMAGE004
、
Figure 909821DEST_PATH_IMAGE005
、
Figure 784236DEST_PATH_IMAGE006
Two adjacent points of the middle zero crossing are respectively connected and the respective connection slope is calculated, and the respective connection slope calculation method comprises the following steps:
step I. set
Figure 551204DEST_PATH_IMAGE004
Two adjacent points of middle zero crossing are Rj (x j, y j)、Rj+1(x j+1,y j+1)；
According to the formula of the slope of the line, Rj (x j, y j)、Rj+1(x j+1,y j+1) The slope calculation formula of the connecting line between the two points is as follows:
Figure 30727DEST_PATH_IMAGE012
；
step II. set
Figure 77311DEST_PATH_IMAGE005
、
Figure 642285DEST_PATH_IMAGE006
Referring to step I by a slope calculation formula of a connecting line between two adjacent points of middle zero crossing;
step III. in the set
Figure 619468DEST_PATH_IMAGE004
、
Figure 812552DEST_PATH_IMAGE005
、
Figure 420251DEST_PATH_IMAGE006
The values of two adjacent points of zero crossing are respectively searched and respectively substituted into a slope calculation formula, and the line voltage slope K of the three phases A, B, C can be obtaineda 、Kb、Kc。
The working principle of the invention is as follows: the three-phase electric energy meter performs related operation on data after being sampled by an ADC (analog to digital converter) of the MCU control unit, and acquires data of two adjacent points of zero crossing, so that the slope, the alternate included angle and the voltage amplitude are obtained; and when the three-phase four-wire access mode is not identified, switching the reference ground, sampling the data waveform again, and acquiring two adjacent point data at the zero crossing so as to obtain the slope, the included angle between phases and the voltage amplitude value, thereby identifying whether the three-phase three-wire connection mode exists.
The specific judgment is as follows:
1. and judging whether the three-phase line voltage can form a triangle or not, if the three-phase line voltage cannot meet the requirement, judging as a wiring error and giving an alarm, otherwise, carrying out the next judgment.
2. And (4) calculating the center of the circumscribed circle according to the voltage of the three-phase line, judging whether the outer center is coincident with the grounding point N or not, if the outer center is not coincident with the grounding point N as shown in fig. 8, continuing to judge in the step 3 as shown below, and otherwise, judging in the step 4 as shown below.
3. And judging whether the three-phase voltages are equal, if not, judging the three-phase four-wire connection mode, and if so, judging that the connection is wrong and giving an alarm.
4. And judging whether the slopes between the two points are all equal when the voltage waveforms of the three-phase lines pass through the zero point, if so, judging that the three-phase lines are three-phase four-line lines, and if not, judging the next step.
5. And judging whether the slope between the two points when the voltage waveform of the three-phase line crosses the zero point is equal to the slope of the phase A and the phase C and not equal to the slope of the phase B, if so, determining that the voltage waveform of the three-phase line is three-phase line, otherwise, determining that the voltage waveform of the three-phase line is wrong in wiring and giving an alarm.
6. The three-phase four-wire connection mode is judged, the voltage specification is judged according to the voltage value, when all three phases are less than or equal to 70V, the three-phase four-wire connection mode is judged to be 3X 57.7/100V, and otherwise, the three-phase four-wire connection mode is judged to be 3X 220/380V.
7. And configuring a metering mode and metering parameters according to the identified wiring mode of the electric energy meter, and updating event related parameters according to the voltage specification.
8. And the load judgment subprogram realizes switching-off operation when the wiring mode is not identified, prompts workers and protects the electric equipment of a user. In the case of recognizing the connection method, the load control action is mainly performed, as shown in fig. 4.

Claims (6)

1. A self-adaptive method for a three-phase electric energy meter in a wiring mode comprises an MCU control unit, an analog data acquisition unit connected with the MCU control unit by means of a metering processing unit, a switching power supply unit connected with the MCU control unit by means of a power supply management unit, a liquid crystal display unit, a storage unit, a communication unit, a key unit, a load control unit and a reference voltage ground switching control unit, wherein the liquid crystal display unit, the storage unit, the communication unit, the key unit, the load control unit and the reference voltage ground switching control unit are connected with the MCU control unit, and the self-adaptive method is characterized by comprising the following steps:
step 1, the analog data acquisition unit carries out waveform acquisition on the voltage of the three-phase line according to the frequency f, data reading is carried out after more than two cycles, and waveform data points on one cycle are respectively recorded as a set
Figure 739697DEST_PATH_IMAGE001
、
Figure 938728DEST_PATH_IMAGE002
、
Figure 515203DEST_PATH_IMAGE003
W is the data number of one cycle;
collection
Figure 972729DEST_PATH_IMAGE004
、
Figure 68992DEST_PATH_IMAGE005
、
Figure 422613DEST_PATH_IMAGE006
Calculating by means of a line voltage effective value formula, and respectively recording the calculation results as Uab、Ubc、Uca；
Meanwhile, the metering processing unit also collects and processes three-phase voltage, and reads the processed data as a three-phase voltage effective value Uan、Ubn、Ucn；
Step 2, U in effective value of line voltageab、UbcAnd UcaIf the sum of any two is larger than the sum of any two and the third party, executing the step 3, otherwise, returning to the step 1;
step 3, utilizing the effective value U of the line voltageab、Ubc、UcaDrawing a triangle, and calculating the radius L of a circumscribed circle of the triangle;
step 4, the radius L of the circumscribed circle is respectively equal to the effective value U of the phase voltagean、Ubn、UcnComparing, if at least one data is not equal, judging that the wiring mode of the electric energy meter is a three-phase four-wire mode, and executing the step 5; otherwise, executing step 6;
step 5, judging Uan、Ubn、UcnWhether the zero line is equal to the zero line is judged, if so, the zero line is not accessed in the three-phase four-wire connection mode of the electric energy meter, and an alarm is given; if the three phases are not equal to each other, judging that the three-phase four-wire connection mode of the electric energy meter is correct;
step 6, respectively finding out the sets by adopting a traversal method
Figure 424067DEST_PATH_IMAGE004
、
Figure 154126DEST_PATH_IMAGE005
、
Figure 619742DEST_PATH_IMAGE006
Two adjacent points of upper zero crossing, pair set
Figure 347527DEST_PATH_IMAGE004
、
Figure 380817DEST_PATH_IMAGE005
、
Figure 648988DEST_PATH_IMAGE006
Two adjacent points of the middle zero crossing are respectively connected and the respective connection slope is calculated, and then the calculation result of the respective connection slope is recorded as Ka、Kb、Kc；
Step 7, judging Ka、Kb、KcWhether the three phases are equal to each other or not is judged, and if the three phases are equal to each other, the wiring mode of the electric energy meter is judged to be a three-phase four-wire mode; if not, executing step 8;
step 8, judging Ka、KcWhether the two phases are equal or not is judged, if so, the wiring mode of the electric energy meter is judged to be a three-phase three-wire mode; if the difference is not equal, the wiring mode is judged to be wrong, and an alarm is given.
2. The self-adaptive method for the wiring mode of the three-phase electric energy meter according to claim 1, characterized in that: aggregation in step 1
Figure 969110DEST_PATH_IMAGE004
、
Figure 133376DEST_PATH_IMAGE005
、
Figure 906159DEST_PATH_IMAGE006
The effective value of the line voltage is calculated by the following formula:
Figure 728753DEST_PATH_IMAGE007
；
Figure 903382DEST_PATH_IMAGE008
；
Figure 972970DEST_PATH_IMAGE009
；
wherein R is1—RWTaken from the collection
Figure 233050DEST_PATH_IMAGE001
Sampling points of (1); t is1—TWTaken from the collection
Figure 843023DEST_PATH_IMAGE002
Sampling points of (1); p1—PWTaken from the collection
Figure 622891DEST_PATH_IMAGE003
The sampling points of (a).
3. The self-adaptive method for the wiring mode of the three-phase electric energy meter according to claim 1, characterized in that: for phase voltage U of three-phase four-wire connection mode in step 5 and step 7an、Ubn、UcnAnd judging that the voltage of the electric energy meter is 3 × 220/380V if one of the three voltages is more than 70V, and judging that the voltage of the electric energy meter is 3 × 57.7/100V if none of the three voltages is more than 70V.
4. The self-adaptive method for the wiring mode of the three-phase electric energy meter according to claim 1, characterized in that: and 8, switching the reference voltage and the reference ground of the electric energy meter in the three-phase three-wire connection mode in the step 8 by controlling the reference voltage ground switching control unit through the MCU control unit to enable the power supply ground wire to be switched from UnSwitch to Ub。
5. The self-adaptive method for the wiring mode of the three-phase electric energy meter according to claim 1, characterized in that: the method for drawing the triangle and solving the radius L of the circumscribed circle in the step 3 comprises the following steps:
taking F (0,0) point as a starting point in a coordinate system and taking a line voltage effective value UabIs positioned on the X axis by the value of G (U)abAnd 0) a point of (A),then the effective value U of the line voltage is addedbc、UcaThe value of (d) is connected as the other two sides of the triangle, and the connection point is H (x)1,y1) Point;
secondly, utilizing a coordinate formula:
Figure 191275DEST_PATH_IMAGE010
，
calculating coordinates of the point H;
with the known F, G, H three-point coordinates, according to the triangle's eccentric characteristics and the system of equations:
Figure 876335DEST_PATH_IMAGE011
；
calculating coordinates of the triangle outer center N' (a, b);
and fourthly, calculating the radius L of the circumscribed circle, namely the distances from the F point, the G point and the H point to the N 'point respectively according to the obtained coordinates of the triangle outsenter N' (a, b).
6. The self-adaptive method for the wiring mode of the three-phase electric energy meter according to claim 1, characterized in that: set pair in step 6
Figure 289999DEST_PATH_IMAGE004
、
Figure 439220DEST_PATH_IMAGE005
、
Figure 663659DEST_PATH_IMAGE006
Two adjacent points of the middle zero crossing are respectively connected and the respective connection slope is calculated, and the respective connection slope calculation method comprises the following steps:
step I. set
Figure 836015DEST_PATH_IMAGE004
Two adjacent points of middle zero crossing are Rj (x j, y j)、Rj+1(x j+1,y j+1)；
According to the formula of the slope of the line, Rj (x j, y j)、Rj+1(x j+1,y j+1) The slope calculation formula of the connecting line between the two points is as follows:
Figure 53369DEST_PATH_IMAGE012
；
step II. set
Figure 57097DEST_PATH_IMAGE005
、
Figure 904968DEST_PATH_IMAGE006
Referring to step I by a slope calculation formula of a connecting line between two adjacent points of middle zero crossing;
step III. in the set
Figure 361357DEST_PATH_IMAGE004
、
Figure 124346DEST_PATH_IMAGE005
、
Figure 717001DEST_PATH_IMAGE006
The values of two adjacent points of zero crossing are respectively searched and respectively substituted into a slope calculation formula, and the line voltage slope K of the three phases A, B, C can be obtaineda 、Kb、Kc。
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