A method for distinguishing abnormal current phase loss of dedicated transformer users

Abstract

The present invention relates to a method for distinguishing abnormal phase loss of current of a dedicated transformer user. The normal data of the other two phases on the low-voltage side of the suspected phase loss user are deduced to the high-voltage side line voltage, and then the calculated value of the phase loss current is obtained by reverse deduction from the high-voltage side line voltage. The longest common subsequence algorithm is used to analyze and judge the calculated value of the phase loss current and the actual values ​​of the other two phases to distinguish whether the phase loss problem is caused by the meter itself or by the existence of two-phase electricity consumption by the dedicated transformer user itself. The method of the present invention can help relevant departments to conduct targeted on-site surveys, avoid excessive duplication of work, reduce the workload of on-site staff, and efficiently maintain the safety of power grid operation.

Description

Technical Field

[0001] The present invention belongs to the field of abnormal electricity consumption of dedicated transformer users, and is applied to a method for identifying meter inaccuracy and user electricity theft, and is particularly suitable for determining the phase loss problem of a phase current in metering data. Specifically, it relates to a method for determining the abnormal phase loss of dedicated transformer user current. Background Art

[0002] Special transformer users generally consume a large amount of electricity, and the metering device is prone to current phase loss faults. Once the fault occurs, the electric energy metering will be deviated. Whether the metering device can operate normally and accurately measure is related to the vital interests of the power department and the user. In work, the metering device of such users is often encountered. Due to various reasons, the current transformer is phase-loss, which causes disputes due to the need to compensate the user for the amount of electricity. In order to enable power marketing personnel to correctly handle such problems, let users know the reasons when such problems occur, and make the compensation work go smoothly, the present invention attempts to analyze the working status of the electric energy metering device when one of the three phases A, B, and C of the current transformer is broken. Through the power consumption data of the special transformer users collected by the user information collection system (the data types used include operating condition data such as voltage, current, power, power factor, etc.), the abnormal current power consumption data is quickly found and the cause of the abnormal data is explored. Such information is delivered to the relevant departments for targeted on-site investigation, avoiding excessive duplication of work, reducing the workload of on-site staff, and efficiently maintaining the safety of power grid operation. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for distinguishing the abnormality of phase loss of current of a dedicated transformer user. When the sampling data of the dedicated transformer user only contains two-phase current data, through reverse deduction, it is analyzed whether the phase loss of current of the dedicated transformer user is caused by the normal current data presented by the user himself using two-phase electricity, or by the abnormality of the current transformer in the metering device.

[0004] To achieve the above objectives, the technical solution of the present invention is: a method for distinguishing abnormal phase loss of current in dedicated transformer users, which derives the normal data of the other two phases on the low-voltage side of the suspected phase loss user to the high-voltage side line voltage, and then reversely deduces the calculated value of the phase loss current from the high-voltage side line voltage. The longest common subsequence algorithm is used to analyze the calculated value of the phase loss current and the actual values ​​of the other two phases to determine whether the phase loss problem is caused by the meter itself or by the dedicated transformer user's own two-phase electricity consumption. The specific implementation steps of this method are as follows:

[0005] Step 1: Collect the operating condition data of 96 points of the dedicated transformer user every day in the electricity consumption information collection system, including voltage, current, active power, reactive power, voltage and current phase, as well as the transformer capacity data in the system archive;

[0006] Step 2: Calculate the average current per phase of the dedicated transformer user on a certain day

[0007]

[0008] Where, is the current value of each phase, i is A, B, C, x=1,2,3,……,96;

[0009] Step 3: Set the current phase loss abnormal threshold. If the average current of a phase of the transformer user is When the current is lower than 30% of the average value of the other two phases, it is identified as a suspected abnormal user;

[0010] Step 4: Obtain the transformer parameters corresponding to the suspected abnormal transformer user, search the transformer capacity data through the system file, and further obtain the transformer equivalent impedance parameter R T 、X T ;

[0011] Step 5: Based on the load characteristic principle, assuming that the suspected abnormal dedicated transformer user has abnormal phase C current, derive the voltage and current data of phase A and phase B of the dedicated transformer user to the high-voltage side line voltage. The specific derivation process is shown in the following formula:

[0012]

[0013]

[0014] Where U a0 、U b0 is the voltage on the primary side of the transformer after conversion, U a 、U b is the three-phase voltage on the low-voltage side collected by the acquisition system, I a , I b is the three-phase current value on the low-voltage side, is the impedance angle;

[0015] Step 6: Calculate the three-phase voltage angle on the high-voltage side of phases A and B. The formula is as follows:

[0016]

[0017]

[0018] ψ a =δ a +β a -β b (6)

[0019] Where, β a , β b is the phase shift, that is, U i0 with Ui The angle between them, i = a, b, c; δ a The angle between the A and B phase voltages collected by the acquisition system, namely U a 、U b The angle between a The voltage angle between phases A and B on the high voltage side is U a0 、U b0 Angle between

[0020] Step 7: Calculate the high-voltage side line voltage U using the triangle side formula LA :

[0021]

[0022] Step 8: The high voltage side of the dedicated transformer user is a 10kV high voltage line. Assuming that the three phases of the external high voltage line are balanced and the amplitudes are close to equal, there is U LA =U LB =U LC ,Right now:

[0023]

[0024] Step 9: Solve for U b0 、U c0 Angle Ψ b , then ψ c =360°-ψ a -ψ b , calculate the high voltage side phase voltage U using the triangle side formula c0 and Ψ b , the specific formula is as follows:

[0025]

[0026]

[0027] Solve equations (8), (9), and (10) together to obtain U c0 ,Ψ b value;

[0028] Step 10: Create U b0 、U c0 Angle Ψ b and C phase impedance angle The relationship between them:

[0029]

[0030] ψ b =δ b +β b -β c (12)

[0031] Where, β c is the phase shift, that is, U c0 with U b0 The angle between b The angle between the B and C phase voltages collected by the acquisition system, namely U b 、U c The angle between b is the voltage angle between phases B and C on the high voltage side, that is, U b0 、U c0 Angle between

[0032] Step 11: The following formula is used to derive the voltage and current data of phase C of the dedicated transformer user to the high-voltage side line voltage:

[0033]

[0034] Step 12: U calculated in step 9 c0 ,Ψ b The value is taken as a known value, and then equations (11), (12), and (13) are solved together to obtain the calculated value of phase C current I at 96 points of the dedicated transformer user on that day. c And the C phase current phase:

[0035]

[0036] Step 13: Use the longest common subsequence algorithm LCSS to calculate the missing phase current I c The similarity between the calculated value and the actual value of the other two-phase currents is as follows: For the A and C phase currents, let the A and C phase current sequence point set be C1 = {a1, a2, ..., a 96} and C2={c1,c2,...,c 96}, then the length of the longest common subsequence is:

[0037]

[0038] Where t = 1, 2, 3, ..., 96; i = 1, 2, 3, ..., 96; γ is the set distance threshold; LCSS (a t , b i ) is the sequence point set C1 at trajectory point a t And the sequence point set C2 at trajectory point b i The maximum common subsequence length before dist(a t , b t ) is the ath t point b in C2 i The distance between points;

[0039] Step 14: Measure the similarity of the curves by calculating the number of trajectory points of the current sequences of phases A and C that meet the distance threshold between points. The matching rate ρ of the two sequence point sets C1 and C2 is calculated as follows:

[0040]

[0041] Where ρ(C1, C2)∈[0, 1]; and the larger the value of ρ(C1, C2), the more similar C1 and C2 are;

[0042] Step 15: Calculate the missing phase current I c The matching rate between the calculated value and the other two-phase current actual value sequence C'={C1,C2,C3} is calculated by dividing each two sets C i and C j The matching degree between them is accumulated, and a judgment threshold η is set through experience. When the accumulated result is higher than η, that is, ∑ρ(C i ,C j )>η, it is considered that the calculated value of the phase-missing current is inconsistent with the actual value, and there is a phenomenon of metering inaccuracy or power theft; when the accumulated result is lower than η and the calculated current I c The average current When the current is lower than 30% of the average value of the other two phases, it is considered that the dedicated transformer user has two-phase power consumption.

[0043] Compared with the prior art, the present invention has the following beneficial effects: Through the present invention, a method for distinguishing the phase-loss problem of the current of a dedicated transformer user based on the load characteristic principle can be realized, by deducing the normal data of the other two phases on the low-voltage side of the suspected phase-loss user to the high-voltage side line voltage, and then reversely deducing the calculated value of the phase-loss current from the high-voltage side line voltage, and using the longest common subsequence algorithm to analyze the calculated value of the phase-loss current and the actual values ​​of the other two phases, it can be determined whether the phase-loss problem is caused by the meter itself or by the fact that the dedicated transformer user itself has two-phase electricity consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Flow chart of the method of the present invention.

[0045] Figure 2 This is the equivalent circuit diagram of the transformer.

[0046] Figure 3 It is the vector diagram of low pressure side and high pressure side.

[0047] Figure 4 It is the three-phase voltage vector conversion diagram. DETAILED DESCRIPTION

[0048] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0049] The present invention provides a method for distinguishing abnormal phase loss of current of a dedicated transformer user. The method derives the normal data of the other two phases on the low-voltage side of the suspected phase loss user to the high-voltage side line voltage, and then reversely deduces the calculated value of the phase loss current from the high-voltage side line voltage. The longest common subsequence algorithm is used to analyze the calculated value of the phase loss current and the actual values ​​of the other two phases. It can be determined whether the phase loss problem is caused by the meter itself or by the two-phase electricity consumption of the dedicated transformer user itself.

[0050] like Figure 1 As shown, the present invention provides a method for distinguishing the abnormality of the current phase loss of a dedicated transformer user, which mainly includes the following steps:

[0051] Step 1: Collect the voltage, current, active power, reactive power, voltage and current phase and other operating condition data of the dedicated transformer user at 96 points every day in the power consumption information collection system, as well as the transformer capacity data in the system archive;

[0052] Step 2: Calculate the average current per phase of the dedicated transformer user on a certain day

[0053]

[0054] Where i is A, B, and C.

[0055] Step 3: Set the current phase loss abnormal threshold. If the average current of a phase of the transformer user is When the current is lower than 30% of the average value of the other two phases, it is identified as a suspected abnormal user;

[0056] Step 4: Obtain the transformer parameters corresponding to the suspected abnormal transformer user, search the transformer capacity data through the system file, and further obtain the transformer equivalent impedance parameter R T 、X T , the transformer equivalent circuit is as follows Figure 2 As shown;

[0057] Step 5: Based on the load characteristic principle, taking the abnormal phase C current of the suspected abnormal transformer user as an example, deduce the voltage and current data of the phase A and phase B of the user to the high-voltage side line voltage, and then calculate the voltage and current data of the phase A and phase B of the user to obtain the voltage of the high-voltage side line. Figure 3 From the vector diagram of the medium and low voltage side and the high voltage side (taking phase A as an example), we can see that the specific derivation process is shown in the following formula:

[0058]

[0059]

[0060] Where U a0 、U b0 is the voltage on the primary side of the transformer after conversion, U a 、U bis the three-phase voltage on the low-voltage side collected by the acquisition system, I a , I b is the three-phase current value on the low-voltage side, is the impedance angle;

[0061] Step 6: Calculate the three-phase voltage angle on the high-voltage side of phases A and B. The formula is as follows:

[0062]

[0063]

[0064] ψ a =δ a +β a -β b (6)

[0065] Where, β a , β b is the phase shift, that is, U i0 with U i The angle between them, i = a, b, c; δ a The angle between the A and B phase voltages collected by the acquisition system, namely U a 、U b The angle between a The voltage angle between phases A and B on the high voltage side is U a0 、U b0 The angle between them. The three-phase voltage vector conversion diagram is as follows Figure 4 As shown;

[0066] Step 7: Calculate the high-voltage side line voltage U using the triangle side formula LA :

[0067]

[0068] Step 8: The high voltage side of the dedicated transformer is a 10kV high voltage line. It can be assumed that the three phases of the external high voltage line are balanced and the amplitudes are also close to equal, so there is U LA =U LB =U LC ,Right now:

[0069]

[0070] Step 9: Solve for U b0 、U c0 Angle Ψ b , then ψ c =360°-ψ a -ψ b , calculate the high voltage side phase voltage U using the triangle side formula c0 and Ψ b , the specific formula is as follows:

[0071]

[0072]

[0073] Solve equations (8), (9), and (10) together to obtain U c0 , Ψ b value.

[0074] Step 10: Create U b0 、U c0 Angle Ψ b and C phase impedance angle The relationship between them:

[0075]

[0076] ψ b =δ b +β b -β c (12)

[0077] Where, β c is the phase shift, that is, U c0 with U b0 The angle between b The angle between the B and C phase voltages collected by the acquisition system, namely U b 、U c The angle between b is the voltage angle between phases B and C on the high voltage side, that is, U b0 、U c0 Angle between

[0078] Step 11: The following formula is used to derive the user's C-phase voltage and current data to the high-voltage side line voltage:

[0079]

[0080] Step 12: U calculated in step 9 c0 , Ψ b The value is taken as a known value, and then equations (11), (12), and (13) are solved together to obtain the calculated value of phase C current I at 96 points of the dedicated transformer user on that day. c And the C phase current phase:

[0081]

[0082] Step 13: Use the longest common subsequence algorithm (LCSS) to calculate the missing phase current I cThe similarity between the calculated value and the actual value of the other two-phase currents is as follows: Taking the A and C phase currents as an example, let the A and C phase current sequence point set be C1 = {a1, a2, ..., a 96} and C2={c1,c2,...,c 96}, then the length of the longest common subsequence is:

[0083]

[0084] Where t = 1, 2, 3, ..., 96; i = 1, 2, 3, ..., 96; γ is the set distance threshold; LCSS (a t , b i ) is the sequence C1 at trajectory point a t and sequence C2 at trajectory point b i The maximum common subsequence length before dist(a t , b t ) is the ath in the C1 trajectory t point and the bth point in the C2 sequence i The distance between points;

[0085] Step 14: Measure the similarity of the curves by calculating the number of trajectory points of the two-phase current sequences A and C that meet the distance threshold between points. The matching rate ρ of the two sequence point sets C1 and C2 is calculated as follows:

[0086]

[0087] Where ρ(C1, C2)∈[0, 1]; and the larger the value of ρ(C1, C2), the more similar the C1 sequence is to the C2 sequence.

[0088] Step 15: Calculate the missing phase current I c The matching rate between the calculated value and the other two-phase current actual value sequence C'={C1,C2,C3} is calculated by dividing each two sets C i and C j The matching degree between them is accumulated, and a judgment threshold η is set through experience. When the accumulated result is higher than η, that is, ∑ρ(C i ,C j )>η, it is considered that the calculated value of the phase-missing current is inconsistent with the actual value, and there is a phenomenon of metering inaccuracy or power theft; when the accumulated result is lower than η and the calculated current I c The average current I c When the current is lower than 30% of the average value of the other two phases, it is considered that the dedicated transformer user has two-phase power consumption.

[0089] The above are preferred embodiments of the present invention. Any changes made according to the technical solution of the present invention, as long as the resulting functions and effects do not exceed the scope of the technical solution of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A method for distinguishing the abnormality of phase loss of current of a dedicated transformer user, characterized in that: The normal data of the other two phases on the low-voltage side of the suspected phase-loss user is deduced to the high-voltage side line voltage, and then the calculated value of the phase-loss current is obtained by reverse deduction from the high-voltage side line voltage. The longest common subsequence algorithm is used to analyze the calculated value of the phase-loss current and the actual values ​​of the other two phases to determine whether the phase-loss problem is caused by the meter itself or by the dedicated transformer user's own two-phase power consumption. The longest common subsequence algorithm is used to analyze the calculated value of the missing phase current and the actual values ​​of the other two phases to determine whether the missing phase problem is caused by the meter itself or by the user's own two-phase power consumption. The specific implementation steps are as follows: S1. Use the longest common subsequence algorithm LCSS to calculate the missing phase current I c The similarity between the calculated value and the actual value of the other two-phase currents is as follows: for the two-phase currents A and C, let the set of the two-phase current sequence points A and C be C1 = {a1, a2, ..., a 96 } and C2={c1,c2,...,c 96 }, then the length of the longest common subsequence is: Where t = 1, 2, 3, ..., 96; i = 1, 2, 3, ..., 96; γ is the set distance threshold; LCSS (a t , b i ) is the sequence point set C1 at trajectory point a t And the sequence point set C2 at trajectory point b i The maximum common subsequence length before dist(a t , b t ) is the ath t point b in C2 i The distance between points; S2. The similarity of the curves is measured by calculating the number of trajectory points of the two-phase current sequences A and C that meet the distance threshold between points. The matching rate ρ of the two sequence point sets C1 and C2 is calculated as follows: Where ρ(C1, C2)∈[0, 1]; and the larger the value of ρ(C1, C2), the more similar C1 and C2 are; S3, calculate the missing phase current I c The matching rate between the calculated value and the other two-phase current actual value sequence C'={C1,C2,C3} is calculated by dividing each two sets C i and C j The matching degree between them is accumulated, and a judgment threshold η is set through experience. When the accumulated result is higher than η, that is, ∑ρ(C i ,C j )>η, it is considered that the calculated value of the missing phase current is inconsistent with the actual value, and there is inaccurate measurement or electricity theft; when the accumulated result is lower than η and the current I c Calculated current average value When the current is lower than 30% of the average value of the other two phases, it is considered that the dedicated transformer user has two-phase power consumption.

2. The method for distinguishing the abnormality of current phase loss of a dedicated transformer user according to claim 1 is characterized in that: The normal data of the other two phases on the low-voltage side of the suspected phase-loss user are deduced to the high-voltage side line voltage, and then the calculated value of the phase-loss current is obtained by reverse deduction from the high-voltage side line voltage. The specific implementation steps are as follows: Step 1: Collect the operating condition data of 96 points of the dedicated transformer user every day in the electricity consumption information collection system, including voltage, current, active power, reactive power, voltage and current phase, as well as the transformer capacity data in the system archive; Step 2: Calculate the average current per phase of the dedicated transformer user on a certain day Where, is the current value of each phase, i is A, B, C, x=1,2,3,……,96; Step 3: Set the current phase loss abnormal threshold. If the average current of a phase of the transformer user is When the current is lower than 30% of the average value of the other two phases, it is identified as a suspected abnormal user; Step 4: Obtain the transformer parameters corresponding to the suspected abnormal transformer user, search the transformer capacity data through the system file, and further obtain the transformer equivalent impedance parameter R T 、X T ; Step 5: Based on the load characteristic principle, assuming that the suspected abnormal dedicated transformer user has abnormal phase C current, derive the voltage and current data of phase A and phase B of the dedicated transformer user to the high-voltage side line voltage. The specific derivation process is shown in the following formula: Where U a0 、U b0 is the voltage on the primary side of the transformer after conversion, U a 、U b is the three-phase voltage on the low-voltage side collected by the acquisition system, I a , I b is the three-phase current value on the low-voltage side, is the impedance angle; Step 6: Calculate the three-phase voltage angle on the high-voltage side of phases A and B. The formula is as follows: ψ a =d a +b a -b b (6) Where, β a , β b is the phase shift, that is, U i0 with U i The angle between them, i = a, b, c; δ a The angle between the A and B phase voltages collected by the acquisition system, namely U a 、U b The angle between a The voltage angle between phases A and B on the high voltage side is U a0 、U b0 Angle between Step 7: Calculate the high-voltage side line voltage U using the triangle side formula LA : Step 8: The high voltage side of the dedicated transformer user is a 10kV high voltage line. Assuming that the three phases of the external high voltage line are balanced and the amplitudes are close to equal, there is U LA =U LB =U LC ,Right now: Step 9: Solve for U b0 、U c0 Angle Ψ b , then ψ c =360°-ψ a -ψ b , calculate the high voltage side phase voltage U using the triangle side formula c0 and Ψ b , the specific formula is as follows: Solve equations (8), (9), and (10) together to obtain U c0 , Ψ b value; Step 10: Create U b0 、U c0 Angle Ψ b and C phase impedance angle The relationship between them: ψ b =d b +b b -b c (12) Where, β c is the phase shift, that is, U c0 with U b0 The angle between b The angle between the B and C phase voltages collected by the acquisition system, namely U b 、U c The angle between b is the voltage angle between phases B and C on the high voltage side, that is, U b0 、U c0 Angle between Step 11: The following formula is used to derive the voltage and current data of phase C of the dedicated transformer user to the high-voltage side line voltage: Step 12: U calculated in step 9 c0 ,Ψ b The value is taken as a known value, and then equations (11), (12), and (13) are solved together to obtain the calculated value of phase C current I at 96 points of the dedicated transformer user on that day. c And the C phase current phase:

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