A method for determining wrong wiring of three-phase three-wire electric energy metering device based on current angle

Abstract

The present invention provides a method for determining the miswiring of a three-phase three-wire electric energy metering device based on current angle, which belongs to the field of electric energy metering technology and includes the following steps: obtaining and processing data such as phase-by-phase active and reactive power; calculating the power factor angle between the voltage and current of the two phases A and C; calculating the angle difference and the angle sum; and determining whether the electric energy metering device is miswired. The present invention uses easily accessible data items such as current and power in an automated meter reading system, and determines whether the electric energy metering device is miswired by calculating the numerical range of the current angle (sum / difference) of the two phases A and C.

Description

Technical Field

[0001] The present invention relates to the technical field of electric energy metering, and in particular to a method for judging wrong wiring of a three-phase three-wire electric energy metering device based on current angle and difference interval. Background Art

[0002] Miswiring inspection is an important part of ensuring the correct measurement of metering devices. Compared with easily detected metering abnormalities such as loss of pressure and loss of current, miswiring events are more hidden, with no obvious data missing or abnormalities, and are not easy to detect with ordinary monitoring methods. Manual troubleshooting requires high technical experience of personnel and is time-consuming and labor-intensive. Although the current remote automated troubleshooting methods can identify most forms of miswiring, there are still some shortcomings. For situations of three-phase imbalance or special load characteristics of users, the system will make wrong judgments, requiring manual review and correction, which consumes additional manpower. Therefore, there is a need for a more accurate method for identifying miswiring of three-phase three-wire electric energy metering devices that can adapt to more special situations. Summary of the invention

[0003] Based on this, the present invention proposes a method for determining the wrong wiring of a three-phase three-wire electric energy metering device based on current angle and difference interval.

[0004] In order to achieve the above objectives, the present invention is implemented by the following technical solutions:

[0005] The method for judging wrong wiring of a three-phase three-wire electric energy metering device based on current angle comprises the following steps:

[0006] Step S1: obtaining the active curve and reactive curve data of the A and C phases of the three-phase three-wire electric energy metering device on a certain day from the automatic meter reading system, combining and preprocessing the data to obtain a valid data group;

[0007] Step S2: Calculate the measured power factor angle α1 between the measured voltage and measured current of phase A and the measured power factor angle α3 between the measured voltage and measured current of phase C based on the split-phase power in the effective data group;

[0008] Step S3: Calculate the angle difference between α1 and α3, which must satisfy the angle difference ∈ [0°, 360°); calculate the angle sum of α1 and α3, which must satisfy half of the angle sum ∈ [0°, 180°);

[0009] Step S4: According to the three-phase three-wire electric energy metering device miswiring identification table, based on the relationship between the measured power factor angles α1, α3 and the angle sum and angle difference between the measured voltage and measured current of phases A and C, determine whether the electric energy metering device has miswiring.

[0010] In step S1, the daily measurement frequency is once every 15 minutes, that is, one day contains 96 time points in total. The active power curve and reactive power curve of phases A and C are combined according to the corresponding time points to obtain 96 groups of data, each group containing four data items of active power and reactive power of phases A and C.

[0011] In step S1, data processing is performed group by group, abnormal data groups are eliminated, and the group with the largest average active power of phases A and C among the remaining data groups is taken as the valid data group.

[0012] In step S2, the measured power factor angles α1 and α3 of phase A and phase C are

[0013] Among them, the measured power factor angle α1 is:

[0014]

[0015] In the formula, P1 is the active power of phase A, and Q1 is the reactive power of phase A; and The value range is

[0016] [-45°, 45°], the value range of α1 is [0°, 360°];

[0017] The measured power factor angle α3 is:

[0018]

[0019] In the formula, P3 is the active power of phase C, and Q3 is the reactive power of phase C; and The value range of is [-45°, 45°], and the value range of α3 is [0°, 360°].

[0020] In step S3,

[0021] The angular difference between α1 and α3 is (α1-α3);

[0022] Half of the sum of the angles α1 and α3 is

[0023] In step S3, if (α1-α3)∈[0°,360°) does not hold,

[0024] Calculate (α1-α3) and take the modulo 360°;

[0025] like Not true.

[0026] calculate And take the remainder of 180°.

[0027] In step S4, the three-phase three-wire electric energy metering device miswiring judgment table lists α1, α3, α1-α3, The numerical range of the four items;

[0028] The three-phase three-wire electric energy metering device wrong wiring judgment table is as follows:

[0029]

[0030] By looking up the table, if any of the four items is not satisfied, there is a wrong wiring.

[0031] In operation, the present invention utilizes easily obtainable data items such as current and power in the automatic meter reading system, and determines whether the electric energy metering device is miswired by calculating the numerical range of the A and C two-phase current angles (sum / difference). The present invention is applicable to miswiring determination in various special situations such as three-phase imbalance and special load properties, and has a high determination accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a flow chart of the implementation of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings.

[0034] The present invention Figure 1 As shown, a method for determining wrong wiring of a three-phase three-wire electric energy metering device based on current angle includes the following steps:

[0035] Step S1: Obtain the active and reactive curve data of the A and C phases of the three-phase three-wire electric energy metering device on a certain day from the automatic meter reading system, combine and pre-process the data to obtain a valid data group, and prepare for subsequent analysis and calculation;

[0036] Step S2: Calculate the measured power factor angle α1 between the measured voltage and measured current of phase A and the measured power factor angle α3 between the measured voltage and measured current of phase C based on the split-phase power in the effective data group;

[0037] Step S3: Calculate the angle difference between α1 and α3, which must satisfy the angle difference ∈ [0°, 360°); calculate the angle sum of α1 and α3, which must satisfy half of the angle sum ∈ [0°, 180°);

[0038] Step S4: According to the three-phase three-wire electric energy metering device miswiring identification table, based on the relationship between the measured power factor angles α1, α3 and the angle sum and angle difference between the measured voltage and measured current of phases A and C, determine whether the electric energy metering device has miswiring.

[0039] In step S1, the daily measurement frequency is once every 15 minutes, that is, a day contains 96 time points in total, and the active power curves and reactive power curves of phases A and C are combined according to the corresponding time points to obtain 96 groups of data, each group containing four data items of active power and reactive power of phases A and C. In this way, the accuracy of judgment is improved and misjudgment is reduced.

[0040] In step S1, data processing is performed group by group, abnormal data groups are eliminated, and the group with the largest average active power of phases A and C among the remaining data groups is taken as the valid data group.

[0041] Data are processed group by group, and data groups with null values, obvious abnormal data, or low active power are eliminated. The group with the largest average active power of phases A and C among the remaining data groups is taken as the valid data group. If there is no valid data group that meets the requirements on that day, the relevant data of another historical day is re-selected for processing until a valid data group is obtained.

[0042] In step S2, the measured power factor angles α1 and α3 of phase A and phase C are

[0043] Among them, the measured power factor angle α1 is:

[0044]

[0045] In the formula, P1 is the active power of phase A, and Q1 is the reactive power of phase A; and The value range is

[0046] [-45°, 45°], the value range of α1 is [0°, 360°];

[0047] The measured power factor angle α3 is:

[0048]

[0049] In the formula, P3 is the active power of phase C, and Q3 is the reactive power of phase C; and The value range of is [-45°, 45°], and the value range of α3 is [0°, 360°].

[0050] In step S3,

[0051] The angular difference between α1 and α3 is (α1-α3);

[0052] Half of the sum of the angles α1 and α3 is

[0053] In step S3, if (α1-α3)∈[0°,360°) does not hold,

[0054] Calculate (α1-α3) and take the modulo 360°;

[0055] like Not true.

[0056] calculate And take the remainder of 180°.

[0057] In step S4, the three-phase three-wire electric energy metering device miswiring judgment table lists α1, α3, α1-α3, The numerical range of the four items;

[0058] The three-phase three-wire electric energy metering device wrong wiring judgment table is as follows:

[0059]

[0060] By looking up the table, if any one of the four items is not satisfied (that is, the four items cannot be satisfied at the same time), there is a wrong wiring.

[0061] The table for judging incorrect wiring of three-phase three-wire electric energy metering device lists various possible situations where the metering result is correct (here, although the reverse phase sequence is incorrectly wired, the metering result is correct and is considered correct). The value range of the table can be used to determine whether there is a wiring error in the three-phase three-wire electric energy metering device. If it is not within the specified range in the table, it is a wrong wiring.

[0062] In order to explain the implementation of the present invention in more detail, the following is an explanation based on a case.

[0063] (1) Data preparation: Based on the daily 96-point phase power curve of a three-phase three-line user, the effective data set is obtained: phase A active power P1 = 7.8 kW, phase C active power P3 = 77.5 kW, phase A reactive power Q1 = 97.2 kvar, phase C reactive power Q3 = -61.1 kvar.

[0064] (2) Determine the angle:

[0065]

[0066] (3) Determine the angle sum and angle difference:

[0067] α1-α3=85.41°-321.75°=

[0068] -236.34°, -236.34°÷360° remainder is 123.66°;

[0069] 203.58°÷180°, remainder is 23.58°;

[0070] By taking the remainder, (α1-α3)∈[0°,360°) is satisfied;

[0071] (4) Determination of wrong wiring type: Check the wrong wiring identification table of three-phase three-wire electric energy metering device and find that this group of angle combinations is not within the value range specified in the table, so it is judged as wrong wiring.

[0072] With regard to the above description of the disclosed embodiments, professionals in the field should understand that the above description is only a specific implementation mode of the present invention and does not limit the protection scope of the present invention. Any technical solution obtained by any equivalent replacement or equivalent transformation should be included in the protection scope of the present invention.

Claims

1. A method for determining wrong wiring of a three-phase three-wire electric energy metering device based on current angle, characterized in that: The following steps are involved: Step S1: obtaining the active curve and reactive curve data of the A and C phases of the three-phase three-wire electric energy metering device on a certain day from the automatic meter reading system, combining and preprocessing the data to obtain a valid data group; Step S2: Calculate the measured power factor angle α1 between the measured voltage and measured current of phase A and the measured power factor angle α3 between the measured voltage and measured current of phase C based on the split-phase power in the effective data group; Step S3: Calculate the angle difference between α1 and α3, which must satisfy the angle difference ∈ [0°, 360°); calculate the angle sum of α1 and α3, which must satisfy half of the angle sum ∈ [0°, 180°); Step S4: according to the three-phase three-wire electric energy metering device wrong wiring identification table, based on the relationship between the measured power factor angles α1 and α3 between the measured voltage and the measured current of the A and C phases and the angle sum and angle difference, determine whether the electric energy metering device has a wrong wiring; In step S3, The angular difference between α1 and α3 is (α1-α3); Half of the sum of the angles α1 and α3 is In step S3, if (α1-α3)∈[0°,360°) does not hold, Calculate (α1-α3) and take the modulo 360°; like Not true. calculate And take the remainder of 180°; In step S4, the three-phase three-wire electric energy metering device miswiring judgment table lists α1, α3, α1-α3, The numerical range of the four items; The three-phase three-wire electric energy metering device wrong wiring judgment table is as follows: By looking up the table, if any of the four items is not satisfied, there is a wrong wiring.

2. The method for determining wrong wiring of a three-phase three-wire electric energy metering device based on current angle according to claim 1 is characterized in that: In step S1, the daily measurement frequency is once every 15 minutes, that is, one day contains 96 time points in total. The active power curve and reactive power curve of phases A and C are combined according to the corresponding time points to obtain 96 groups of data, each group containing four data items of active power and reactive power of phases A and C.

3. The method for determining wrong wiring of a three-phase three-wire electric energy metering device based on current angle according to claim 2 is characterized in that: In step S1, data processing is performed group by group, abnormal data groups are eliminated, and the group with the largest average active power of phases A and C among the remaining data groups is taken as the valid data group.

4. The method for determining wrong wiring of a three-phase three-wire electric energy metering device based on current angle according to claim 1, characterized in that: In step S2, the measured power factor angles α1 and α3 of phase A and phase C are measured, wherein the measured power factor angle α1 is: In the formula, P1 is the active power of phase A, and Q1 is the reactive power of phase A; and The value range of is [-45°, 45°], and the value range of α1 is [0°, 360°]; The measured power factor angle α3 is: In the formula, P3 is the active power of phase C, and Q3 is the reactive power of phase C; and The value range of is [-45°, 45°], and the value range of α3 is [0°, 360°].

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