Method for checking current phase sequence of power distribution measurement terminal by comparing line current phase difference

Abstract

The invention discloses a method for checking a current phase sequence of a power distribution measurement terminal by comparing a line current phase difference, which comprises the following steps of: acquiring three-phase voltage of a 10kV bus of a transformer substation and active power P and reactive power Q of a 10kV line interval based on wide-area synchronization information, and calculating a power factor angle of the 10kV line interval of the transformer substation in real time; further calculating the difference value between the power factor angle of each 10kV line interval of the transformer substation and the power factor angle of the 10kV reference line by taking the power factor angle of a certain 10kV line interval of the transformer substation as a reference; taking a certain phase current of the power distribution measurement terminal at the head end of the reference 10kV line of the transformer substation as a reference, calculating a phase difference angle of a certain phase current of the power distribution measurement terminal at the head end of each 10kV line lagging behind a certain phase current of the power distribution measurement terminal at the head end of the 10kV reference line, and comparing the difference values of the two angles to be close or meet corresponding conditions; and the phase sequence of each phase current of the measuring terminal on each 10kV distribution line can be automatically checked.

Description

Technical Field

[0001] The present invention relates to a method for verifying the current phase and phase sequence of a distribution measurement terminal by comparing the phase difference of line currents, belonging to the technical field of protection and control of power distribution networks. Background Art

[0002] In the prior art, in an ungrounded system, an arc suppression coil grounded system, and a small resistance grounded system, current measurement terminals (SGS for overhead type and RCMU for cable type) are installed at each measurement point on a 10 kV distribution line as measurement terminals for detecting the current in a certain line segment during a single-phase ground or interphase short circuit fault. After the above measurement terminals are installed, it is necessary to check the three-phase current phase and phase sequence to ensure that the phase currents of each phase A, B, and C of each measurement terminal on all distribution lines of the 10 kV bus of the substation are similar, the phase sequence is the positive phase sequence (abbreviated as the phase currents and phase sequence of each phase of the line are correct), and the correct operation of each measurement terminal. For how to make the comparison, currently, it is generally verified by experience: for example, by observing whether the phase currents of each phase of each line measurement terminal on the 10 kV bus of the substation are similar. This approach often leads to incorrect judgments. For example, when there is local power generation or new energy generation on the line, there will be reverse power flow of active power and reactive power into the power grid, and the above conclusion will not hold. The present invention proposes a relay protection technical solution for an ungrounded system, an arc suppression coil grounded system, and a small resistance grounded system in a 10 kV system. Based on wide-area synchronous information, the three-phase voltages of the 10 kV bus of the substation, the active power P and reactive power Q of the 10 kV line interval are collected, and the power factor angle of the 10 kV line interval of the substation is calculated in real time; further, based on the power factor angle of a certain 10 kV line interval of the substation or the three-phase voltages of the bus, the difference between the power factor angles of each 10 kV line interval of the substation and the power factor angle of the 10 kV reference line is calculated; then, based on the phase A current of the distribution measurement terminal at the head end of the reference 10 kV line of the substation or the three-phase voltages of the bus, the phase difference angle by which the current of a certain phase of the distribution measurement terminal at the head end of each 10 kV line lags behind the current of the distribution measurement terminal at the head end of the 10 kV reference line is calculated, and by comparing that these two angle differences should be similar or the difference between the two satisfies the corresponding conditions, the phase sequence of each phase current of each measurement terminal on the 10 kV distribution line is automatically verified and checked. Summary of the Invention

[0003] In order to solve the problems described in the background technology part, the purpose of the present invention is to collect the three-phase voltage of the 10kV busbar of the substation and the active power P and reactive power Q of the 10kV line interval based on the wide area synchronization information in the 10kV system which is an ungrounded system, an arc suppression coil grounding system, and a low resistance grounding system, and calculate the power factor angle of the 10kV line interval of the substation in real time; further, based on the power factor angle of a certain 10kV line interval of the substation, calculate the power factor angle of each 10kV line interval of the substation and the power factor angle of the 10kV line interval of the substation. kV reference line power factor angle difference; then take the distribution measurement terminal at the head end of the benchmark 10kV line of the substation as the benchmark, or take the bus three-phase voltage as the benchmark, calculate the phase difference angle of the distribution measurement terminal at the head end of each 10kV line that lags behind the distribution measurement terminal at the head end of the 10kV reference line, compare the two angle differences should be close or the difference between the two meets the corresponding conditions, and realize the relay protection method of automatically checking the phase and phase sequence of each phase current of the measurement terminal on each 10kV distribution line.

[0004] To achieve the above object, the present invention adopts the following technical solution:

[0005] A method for checking the phase sequence of current at a distribution measurement terminal by comparing the phase difference of line currents comprises the following steps:

[0006] Step 1), first confirm whether the phase sequence of the three-phase current at the head-end power distribution measurement terminal is correct, and then dispatch the master station system at the master station or substation to perform the following method:

[0007] ⑴ Real-time collection of the three-phase voltage of the 10kV busbar of the substation, the active power P and reactive power Q of each 10kV line interval, and real-time calculation of the power factor angle of each 10kV line interval of the substation

[0008] (2) Take a certain line interval power factor angle As a benchmark (generally a line close to 0° is selected), the power factor angle of each 10kV line interval of the substation is calculated in real time. Power factor angle from the reference line The angle difference between

[0009] ⑶ Collect the three-phase current of the distribution measurement terminal at the head end of each 10kV line at the same time as step ⑴, and calculate the phase angle of the three-phase current of the distribution measurement terminal at the head end of each 10kV line based on a certain phase current of the distribution measurement terminal at the head end of the reference line in step ⑵ The phase difference between the phase angle of the three-phase current at the distribution measurement terminal at the head end of each 10kV line and the phase angle of a phase current at the distribution measurement terminal at the head end of the reference line is further calculated.

[0010] Alternatively, collect the three-phase currents of the distribution measurement terminal at the head end of the 10 kV line at the same time as step (1), and, taking the three-phase voltages of the 10 kV busbar of the substation as the reference, calculate in real time the phase angles by which the currents of each phase of the distribution measurement terminal at the head end of the 10 kV line of the substation lag behind the voltages of each phase of the 10 kV busbar of the substation. Taking the current of a certain phase of the distribution measurement terminal at the head end of the reference line in step (2) as the reference, calculate the phase difference angles between the three-phase currents of the distribution measurement terminals at the head ends of each 10 kV line and the current of a certain phase of the distribution measurement terminal at the head end of the reference line.

[0011] (4) By calculating and comparing the phase difference angles of the currents of a certain phase of the distribution measurement terminals at the head ends of each 10 kV line and the power factor angle differences of the corresponding 10 kV line intervals of the substation the differences between these two angles judge whether it meets the qualified standard;

[0012] ① When the qualified standard is met, it indicates that the phase sequence of the currents of each phase of the distribution measurement terminal at the head end of the 10 kV line is correct;

[0013] ② If the qualified standard is not met, it indicates that the phase sequence is incorrect, and the phase sequence of the currents of each phase of this distribution measurement terminal needs to be adjusted and corrected. The adjustment and correction method is as follows:

[0014] When taking the current of phase A of the reference line of the substation as the reference, mark the phase with the smallest difference as phase A, and then adjust the phase angles of the other two-phase currents and mark them as phase B and phase C in sequence according to the requirements of the positive phase sequence (in the vector diagram, in the clockwise direction);

[0015] When taking the current of phase B of the reference line of the substation as the reference, mark the phase with the smallest difference as phase B, and then adjust the phase angles of the other two-phase currents and mark them as phase C and phase A in sequence according to the requirements of the positive phase sequence (in the vector diagram, in the clockwise direction);

[0016] When taking the current of phase C of the reference line of the substation as the reference, mark the phase with the smallest difference as phase C, and then adjust the phase angles of the other two-phase currents and mark them as phase A and phase B in sequence according to the requirements of the positive phase sequence (in the vector diagram, in the clockwise direction);

[0017] Step (2): On the basis of confirming the phase sequence of the three-phase currents of the distribution measurement terminal at the head end, further verify the phase sequence of the three-phase currents of each distribution measurement terminal downstream of the distribution measurement terminal at the head end; The verification time is preferably selected at the time point with the smallest load fluctuation, avoiding the power generation period of local power plants on the line, reducing the verification error and preventing misjudgment.

[0018] The master station system at the dispatching master station end or the substation end performs the following steps:

[0019] ⑴ Collect the three-phase currents of the i-th first-end distribution measurement terminal and each downstream distribution measurement terminal, and use the current phase of a certain phase among the three phases of the first-end distribution measurement terminal of this line as a reference to calculate in real time the phase angle by which the current of this phase of each distribution measurement terminal on this line lags behind the current of this phase of the first-end distribution measurement terminal

[0020] ⑵ Calculate the phase difference angle of a certain phase current between each downstream distribution measurement terminal and the first-end distribution measurement terminal on the 10kV line and the phase angle of a certain phase current of the distribution measurement terminal at the first end on the 10kV line and determine whether the difference between these two angles meets the qualified standard:

[0021] ① If it meets the qualified standard, it means that the phase and phase sequence of each phase current of the downstream distribution measurement terminals on the 10kV line are correct;

[0022] ② If it does not meet the qualified standard, the phase and phase sequence of each phase current of this distribution measurement terminal need to be adjusted and corrected;

[0023] The method of adjustment and correction is as follows:

[0024] When taking the phase angle of the A-phase current of the first-end distribution measurement terminal as the reference, mark the phase with the smallest difference as the A phase, and then adjust and mark the phases of the other two phases as the B phase and the C phase in sequence according to the positive phase sequence requirements;

[0025] When taking the phase angle of the B-phase current of the first-end distribution measurement terminal as the reference, mark the phase with the smallest difference as the B phase, and then adjust and mark the phases of the other two phases as the C phase and the A phase in sequence according to the positive phase sequence requirements;

[0026] When taking the phase angle of the C-phase current of the first-end distribution measurement terminal as the reference, mark the phase with the smallest difference as the C phase, and then adjust and mark the phases of the other two phases as the A phase and the B phase in sequence according to the positive phase sequence requirements.

[0027] Preferably, the power factor angle of each 10kV line breaker interval in the substation described in step 1) is:

[0028]

[0029] In formula (1): P is the active power of each 10kV line breaker interval in the substation, and Q is the reactive power of each 10kV line breaker interval in the substation; φ represents phase A or phase B or phase C; i ranges from 1 to n, representing the i-th line; the directions of P and Q are specified as follows: it is set that the line loads P and Q are in the positive direction when sent from the substation bus to the line. That is, the active power P sent from the substation bus to the line is + (positive direction), and the reactive power Q sent from the substation bus to the line is + (positive direction).

[0030] Preferably, steps 1) to 2) require calculating the current phase angles of the phase A current, phase B current, phase C current of the j-th set of distribution measurement terminals on the i-th 10kV line with the phase current of a certain phase of the reference line as the reference. The calculation formula is: In formula (2),

[0031]

[0032] is the phase angle of the phase A current, phase B current, phase C current of the j-th set of distribution measurement terminals on the i-th line, φ represents phase A or phase B or phase C, represents the phase A current or phase B current or phase C current of the reference line, represents the phase A current or phase B current or phase C current flowing through the j-th set of distribution measurement terminals on the i-th line, i represents the i-th line, i ranges from 1 to n; j represents the j-th set of distribution measurement terminals on the i-th line, j ranges from 1 to m;

[0033] In addition, when step 1) requires using the three-phase voltage of the substation bus as the reference, calculate the current phase angles of the phase A current, phase B current, phase C current of the first set (the first set) of distribution measurement terminals on the i-th 10kV line. The calculation formula is: In formula (3),

[0034]

[0035] is the phase angle of the phase A current, phase B current, phase C current of the first set of distribution measurement terminals on the i-th line, and Indicates the three-phase voltage of the 10kV bus of the substation

[0036] Preferably, in step 1), the power factor angle of the reference line interval is used as the reference to calculate the power factor angles of each 10kV line interval of the substation in real time And the angle difference between the power factor angle of the reference line interval And the power factor angle of the reference line interval Is calculated

[0037] Preferably, in step 1), the calculation is based on a certain phase current of the distribution measurement terminal at the head of the reference line, or on the three-phase voltage of the substation bus, and the three-phase current phase angles of the distribution measurement terminals at the heads of each 10kV line interval of the substation are calculated in real time And the angle difference between the three-phase current phase angles of the distribution measurement terminal at the head of the reference line Is calculated

[0038] Preferably, in step 1), the phase difference angles of the three-phase currents of the distribution measurement terminals at the heads of each 10kV line described in (4) are compared And the angle difference of the power factor of the corresponding 10kV line interval of the substation The difference between these two angle differences The calculation formula is as follows

[0039]

[0040] The difference between the two angle differences calculated for each line And Is calculated The qualified standard is ±20°

[0041] Preferably, in step 2), the current phase of a certain phase current of the distribution measurement terminal at the head of the corresponding reference line Is used as the reference, and the angle difference between the phase angle of a certain phase current of the jth set of distribution measurement terminals on the ith line downstream of the head of a certain 10kV line and the phase angle of a certain phase current of the distribution measurement terminal at the head Is calculated And the phase angle of a certain phase current of the distribution measurement terminal at the head The difference between these two angles The calculation formula is as follows

[0042]

[0043] The calculated angle difference The qualified standard is ±20°

[0044] Preferably, the voltage level of the distribution line applicable to the present invention is 6 kV to 35 kV, and it is used in an ungrounded system, an arc suppression coil grounded system, or a small resistance grounded system with a 6 kV to 35 kV system grounding method.

[0045] The method of the present invention can also be applied to the verification of the three-phase current phase sequence of a distribution automation terminal (FTU).

[0046] By means of the above solution, the present invention has at least the following advantages:

[0047] 1. By collecting the active power P and reactive power Q of the 10 kV line interval of the substation, calculating the power factor angle of the line and the difference in power factor from the reference line, and simultaneously collecting the three-phase currents of phases A, B, and C of the distribution measurement terminal at the head end of the line, with the current of a certain phase of the distribution measurement terminal at the head end of the reference line as the reference, calculating the phase difference angle of the three-phase currents of the distribution measurement terminal at the head end of the substation for this line, and then calculating the difference between the difference in the phase angles of the currents of each phase of the distribution measurement terminal at the head end of the 10 kV line and the power factor angle difference of the three-phase currents of the 10 kV line interval of the substation, and judging whether it is within the qualified range, the phase sequence of the three-phase currents of phases A, B, and C of the distribution measurement terminal at the head end of this line can be judged very accurately, which is beneficial to quickly and accurately judging faults in the 10 kV distribution network.

[0048] 2. With the current of a certain phase of the distribution measurement terminal at the head end of the reference line as the reference, by collecting the three-phase currents of phases A, B, and C of each distribution measurement terminal on this line, calculating the phase angles of the three-phase currents at each measurement point, and then calculating the difference between the phase angle of the current of a certain phase of each distribution measurement terminal downstream of the head end of the 10 kV line and the phase angle of the current of this phase of the distribution measurement terminal at the head end, and judging whether it is within the qualified range, the phase sequence of the three-phase currents of phases A, B, and C of each distribution measurement terminal on this line can be judged very accurately. The implementation scheme is simple and easy to implement, which is beneficial to improving the power supply reliability of the 10 kV distribution network.

[0049] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly and implement it according to the content of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. Description of the Drawings

[0050] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, so they should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts.

[0051] Figure 1 It is the single-line diagram of the connection of two 10kV distribution lines of the present invention;

[0052] Figure 2 It is the flow chart for discriminating the current phase sequence of the distribution measurement terminal of the 10kV line by verifying with phase A as the reference of the present invention. Specific embodiments

[0053] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. The components of the embodiments of the present application usually described and illustrated in the drawings here can be arranged and designed in various different configurations.

[0054] Therefore, the following detailed description of the embodiments of the present application provided in the attached Figure 1 , 2 is not intended to limit the scope of the present application claimed, but merely represents the selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts fall within the scope of protection of the present application.

[0055] In a 10kV system that is an ungrounded system, an arc suppression coil grounded system, or a small resistance grounded system, based on wide-area synchronous information, a main station for single-phase grounding or interphase fault discrimination is set at the dispatching main station end or the substation end. By collecting the three-phase voltages of the 10kV busbar of the substation and the active power P and reactive power Q of the 10kV line interval, the power factor angle of the 10kV line interval of the substation is calculated in real time; taking the power factor angle of a certain line interval as the reference, the difference between the power factor angles of each 10kV line interval of the substation and the power factor angle of the reference line interval is calculated in real time; taking the current of a certain phase of the above reference line as the reference, the three-phase currents of the distribution measurement terminal at the head end of the 10kV line are further collected, and the phase difference angle between the currents of each phase of the distribution measurement terminal at the head end of each 10kV line of the substation and the current of phase A of the reference line is calculated in real time; by comparing and calculating the difference between the two difference angles of the power factor angle differences of each line interval and the phase difference angles of the distribution measurement terminals at the head ends of each 10kV line, according to the judgment criteria, a relay protection method for automatically verifying the phase sequence of the currents of each phase of the measurement terminals on each 10kV distribution line is realized.

[0056] Specifically, the method for verifying the current phase sequence of the distribution measurement terminal by comparing the phase differences of line currents of the present invention includes the following steps:

[0057] Step 1), first confirm whether the three-phase current phase sequence of the distribution measurement terminal at the head end is correct. The main station system at the dispatching main station end or the substation end shall execute the following method:

[0058] ⑴ Collect the three-phase voltages of the 10kV busbars of the substation and the active power P and reactive power Q of each 10kV line interval in real time, and calculate the power factor angle of each 10kV line interval of the substation in real time

[0059] ⑵ Take the power factor angle of a certain line interval as the reference (generally select the line close to 0°), and calculate the power factor angle of each 10kV line interval of the substation and the power factor angle of the reference line interval in real time, and calculate the angle difference

[0060] ⑶ Collect the three-phase currents of the distribution measurement terminal at the head end of each 10kV line at the same time as in step ⑴. Take a certain phase current of the distribution measurement terminal at the head end of the reference line in step ⑵ as the reference, and calculate the phase angle of the three-phase currents of the distribution measurement terminal at the head end of each 10kV line Then further calculate the phase difference angle between the phase angle of the three-phase currents of the distribution measurement terminal at the head end of each 10kV line and the phase angle of a certain phase current of the distribution measurement terminal at the head end of the reference line

[0061] Or, collect the three-phase currents of the distribution measurement terminal at the head end of the 10kV line at the same time as in step ⑴. Take the three-phase voltages of the 10kV busbars of the substation as the reference, and calculate the phase angle by which each phase current of the distribution measurement terminal at the head end of the 10kV line of the substation lags behind each phase voltage of the 10kV busbars of the substation in real time Take a certain phase current of the distribution measurement terminal at the head end of the reference line in step ⑵ as the reference, and calculate the phase difference angle between the three-phase currents of the distribution measurement terminal at the head end of each 10kV line and the phase angle of a certain phase current of the distribution measurement terminal at the head end of the reference line

[0062] (4) By calculating and comparing the phase difference angle of a certain phase current of the distribution measurement terminal at the head end of each 10kV line and the power factor angle difference of the corresponding 10kV line interval of the substation, judge whether the difference of these two angle differences meets the qualified standard;

[0063] ① When the qualified standard is met, it means that the phase sequence of each phase current of the distribution measurement terminal at the head end of the 10kV line is correct;

[0064] ②If the qualified standard is not met, it indicates that the phase and phase sequence are incorrect, and the phase and phase sequence of each phase current of the distribution measurement terminal need to be adjusted and corrected. The adjustment and correction method are as follows:

[0065] When taking the A-phase current of the reference line of the substation as the reference, take the difference The phase with the smallest difference is marked as the A phase, and then the phase angles of the other two-phase currents are adjusted and marked as the B phase and C phase in sequence according to the requirements of the positive phase sequence (in the vector diagram, in the clockwise direction);

[0066] When taking the B-phase current of the reference line of the substation as the reference, take the difference The phase with the smallest difference is marked as the B phase, and then the phase angles of the other two-phase currents are adjusted and marked as the C phase and A phase in sequence according to the requirements of the positive phase sequence (in the vector diagram, in the clockwise direction);

[0067] When taking the C-phase current of the reference line of the substation as the reference, take the difference The phase with the smallest difference is marked as the C phase, and then the phase angles of the other two-phase currents are adjusted and marked as the A phase and B phase in sequence according to the requirements of the positive phase sequence (in the vector diagram, in the clockwise direction);

[0068] Step 2), on the basis of confirming the phase and phase sequence of the three-phase current of the distribution measurement terminal at the head end, further verify the phase and phase sequence of the three-phase current of each distribution measurement terminal downstream of the head end distribution measurement terminal; The verification time is preferably selected at the time point with the smallest load fluctuation, avoiding the power generation period of local power plants on the line, reducing the verification error and preventing misjudgment.

[0069] The main station system at the dispatching main station end or substation end shall execute the following steps:

[0070] ⑴Collect the three-phase currents of the i-th head-end distribution measurement terminal and each downstream distribution measurement terminal, and use the current phase of a certain phase current among the three phases of the head-end distribution measurement terminal of this line as the reference, and calculate in real time the phase angle by which the current of this phase of each distribution measurement terminal on this line lags behind the current of this phase of the head-end distribution measurement terminal

[0071] ⑵Calculate the phase difference angle of a certain phase current of each downstream distribution measurement terminal from the head end on the 10kV line and the phase angle of a certain phase current of the distribution measurement terminal at the head end on the 10kV line The difference between these two angles Judge whether it meets the qualified standard:

[0072] ①If the qualified standard is met, it indicates that the phase and phase sequence of each phase current of the distribution measurement terminal downstream from the head end on the 10kV line are correct;

[0073] ② If the qualified standard is not met, it is necessary to adjust and correct the phase sequence of the phase currents of each phase of the distribution measurement terminal;

[0074] The method of adjustment and correction is as follows:

[0075] When taking the phase current phase angle of phase A of the distribution measurement terminal at the head end as the reference, mark the phase with the smallest difference as phase A, and then adjust and mark the phases of the other two phases as phase B and phase C in sequence according to the requirements of the positive phase sequence;

[0076] When taking the phase current phase angle of phase B of the distribution measurement terminal at the head end as the reference, mark the phase with the smallest difference as phase B, and then adjust and mark the phases of the other two phases as phase C and phase A in sequence according to the requirements of the positive phase sequence;

[0077] When taking the phase current phase angle of phase C of the distribution measurement terminal at the head end as the reference, mark the phase with the smallest difference as phase C, and then adjust and mark the phases of the other two phases as phase A and phase B in sequence according to the requirements of the positive phase sequence.

[0078] Furthermore, the power factor angle of each 10kV line breaker interval in the substation described in step 1) is:

[0079]

[0080] In formula (8): P is the active power of each 10kV line breaker interval in the substation, Q is the reactive power of each 10kV line breaker interval in the substation; φ represents phase A or phase B or phase C; i is from 1 to n, representing the i-th line; the directions of P and Q are specified as follows: it is set that the line load P and Q are in the positive direction from the substation bus to the line. That is, the active power P is in the positive direction from the substation bus to the line, and the reactive power Q is in the positive direction from the substation bus to the line.

[0081] Furthermore, steps 1) to 2) require taking the phase current of a certain phase of the reference line as the reference to calculate the phase current of phase A of phase B of phase C of the j-th set of distribution measurement terminals on the i-th 10kV line.

[0082]

[0083] In formula (9), is the phase current of phase A of the j-th set of distribution measurement terminals on the i-th line phase current of phase B phase current of phase C The phase angle, where φ represents the A-phase or B-phase or C-phase, represents the current of phase A of the reference line or the current of phase B or the current of phase C represents the current of phase A flowing through the j-th distribution measurement terminal of the i-th line or the current of phase B or the current of phase C i represents the i-th line, where i ranges from 1 to n; j represents the j-th set of distribution measurement terminals on the i-th line, where j ranges from 1 to m;

[0084] Moreover, step 1) requires calculating the current phase angle of phase A of the first set of distribution measurement terminals of the i-th line on the 10kV line the current of phase B the current of phase C with the three-phase voltage of the substation bus as the reference The calculation formula is:

[0085]

[0086] (In formula (10), represents the phase angle of phase A the phase angle of phase B the phase angle of phase C current of the first set of distribution measurement terminals of the i-th line, represents the three-phase voltage of the 10kV bus of the substation

[0087] Furthermore, in step 1), the power factor angle of the reference line interval is used as the reference to calculate in real time the power factor angle of each 10kV line interval of the substation and the power factor angle of the reference line interval the angular difference between them

[0088] Furthermore, in step 1), the calculation is based on the current of a certain phase of the distribution measurement terminal at the head end of the reference line, or the three-phase voltage of the substation bus as the reference, and the three-phase current phase angles of the distribution measurement terminals at the head ends of each 10kV line interval of the substation are calculated in real time and the three-phase current phase angles of the distribution measurement terminal at the head end of the reference line the angular difference between them

[0089] Furthermore, in step 1), comparing the three-phase current phase difference angles of the distribution measurement terminals at the head ends of each 10kV line as described in (4) The power factor angle difference of 10kV line interval corresponding to the substation The difference between these two angles The calculation formula is:

[0090]

[0091] The calculated two angle differences for each line and The difference between The acceptance standard is ±20°.

[0092] Further, in step 2), the current of a phase of the terminal corresponding to the head end of the reference line is measured. The current phase As a benchmark, the phase angle of a phase current at the jth distribution measurement terminal of the i-th line downstream of a 10kV line is The phase angle of a phase current at the distribution measurement terminal at the head end The difference between these two angles The calculation formula is:

[0093]

[0094] Calculated angle difference The acceptance standard is ±20°.

[0095] The voltage level of the distribution line applicable to the present invention is 6kV-35kV, and the grounding modes used in the 6kV-35kV system are an ungrounded system, a grounding system through an arc suppression coil, and a low-resistance grounding system.

[0096] The following embodiments all take 10 kV as an example.

[0097] Embodiment 1: Phase and sequence verification of three-phase current at the distribution measurement terminal at the head end of each 10kV line in the substation

[0098] A substation has 9 10kV lines. The active power P and reactive power Q measured at each 10kV line interval are obtained. Based on P and Q, the power factor angle is calculated. Further calculate the difference between the power factor angle of each line and the reference line See Table 1; Taking the A-phase current of the reference line as the reference, the A-phase current phase of the distribution measurement terminal at the head end of each 10kV line is measured. The phase difference between the A phase current and the reference line current Then calculate the phase current of the A phase of the power distribution measurement terminal at the head end of the line and the phase of the reference line The difference Difference between the calculated power factor angle and The difference between these two differences The phase verification is shown in Table 1.

[0099] Table 1 Three-phase current phase and sequence verification table of the distribution measurement terminal at the head of the 10kV line of a certain substation

[0100]

[0101] Comparing with the phase difference angle between the A-phase currents, we have: there are errors in the three-phase current phases of the current measurement terminals at the heads of Line 4 and Line 5, where CAB corresponds to ABC, and there is an error in the three-phase current phase of the current measurement terminal at the head of Line 8, where BCA corresponds to ABC.

[0102] Example 2: Verification of the three-phase current phase and sequence of the distribution measurement terminal downstream of the head of a 10kV line of a certain substation

[0103] A total of 9 sets of distribution measurement terminals are installed on a 10kV line of a certain substation, which are installed on poles No. 18, No. 35, No. 51, No. 57, No. 75, No. 85, No. 106, No. 116, and No. 119 respectively. Measure the phase of each phase current at each measurement point of this line at night, and then calculate the phase angle with the A-phase current of the distribution measurement terminal at the head. If it is within ±10, the verification is correct. The phase verification is shown in Table 2.

[0104] Table 2 Three-phase current phase and sequence verification table of the distribution measurement terminal downstream of the head of a 10kV line of a certain substation

[0105]

[0106] In addition to the above embodiments, the present invention can also have other implementation manners. All technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope required by the present invention.

Claims

1. A method for checking the phase sequence of current at a distribution measurement terminal by comparing the phase difference of line currents, characterized in that: The following steps are involved: Step 1), first confirm whether the phase sequence of the three-phase current at the head-end power distribution measurement terminal is correct, and then dispatch the master station system at the master station or substation to perform the following method: ⑴ Real-time collection of the three-phase voltage of the 10kV busbar of the substation, the active power P and reactive power Q of each 10kV line interval, and real-time calculation of the power factor angle of each 10kV line interval of the substation (2) Take a certain line interval power factor angle Based on the power factor angle of each 10kV line interval in the substation, the power factor angle is calculated in real time. Power factor angle from the reference line The angle difference between ⑶ Collect the three-phase current of the distribution measurement terminal at the head end of each 10kV line at the same time as step ⑴, and calculate the phase angle of the three-phase current of the distribution measurement terminal at the head end of each 10kV line based on a certain phase current of the distribution measurement terminal at the head end of the reference line in step ⑵ The phase difference between the phase angle of the three-phase current at the distribution measurement terminal at the head end of each 10kV line and the phase angle of a phase current at the distribution measurement terminal at the head end of the reference line is further calculated. Alternatively, collect the three-phase current of the distribution measurement terminal at the head end of the 10kV line at the same time as step (1), and use the three-phase voltage of the 10kV busbar of the substation as the reference to calculate in real time the phase angle of the current of each phase of the distribution measurement terminal at the head end of the 10kV line of the substation lagging behind the phase voltage of each phase of the 10kV busbar of the substation Taking the phase current of the distribution measurement terminal at the head end of the reference line in step (2) as the reference, calculate the phase difference between the three-phase current of the distribution measurement terminal at the head end of each 10kV line and the phase angle of the phase current of the distribution measurement terminal at the head end of the reference line. (4) By calculating and comparing the phase difference angle of a phase current at the distribution measurement terminal at the head end of each 10kV line The power factor angle difference of 10kV line interval corresponding to the substation The difference between these two angles Determine whether the eligibility criteria are met; ① When the qualified standard is met, it means that the phase sequence of each phase current at the distribution measurement terminal at the head end of the 10kV line is correct; ② If the qualified standard is not met, it means that the phase sequence is wrong, and the phase sequence of each phase current of the power distribution measurement terminal needs to be adjusted and corrected. The adjustment and correction method is as follows: When the A phase current of the substation reference line is used as the reference, the difference is taken The smallest phase is marked as phase A, and then the other two phases are adjusted in sequence according to the positive phase sequence requirements and marked as phase B and phase C; When the B-phase current of the substation reference line is used as the reference, the difference is taken The smallest phase is marked as phase B, and then the other two phases are adjusted in sequence according to the positive phase sequence requirements and marked as phase C and phase A; When the C phase current of the substation reference line is used as the reference, the difference is taken The smallest phase is marked as phase C, and then the other two phases are adjusted in sequence according to the positive phase sequence requirements and marked as phase A and phase B; Step 2), based on the confirmation of the phase sequence of the three-phase current of the head-end distribution measurement terminal, further verify the phase sequence of the three-phase current of each distribution measurement terminal downstream of the head-end distribution measurement terminal; The master station system at the dispatching master station or substation performs the following steps: ⑴ Collect the three-phase current of the distribution measurement terminal at the head end of the i-th line and each downstream distribution measurement terminal, and use the current of one of the three phases of the distribution measurement terminal at the head end of this line The current phase As a benchmark, the phase angle of each phase current of each distribution measurement terminal on the line lagging behind the phase current of the head distribution measurement terminal is calculated in real time. (2) Calculate the phase difference angle of a phase current at each distribution measurement terminal downstream of the head end of the 10kV line The phase angle of a phase current at the distribution measurement terminal at the head end of the 10kV line The difference between these two angles Determine whether it meets the eligibility criteria: ① If the qualified standard is met, it means that the phase and phase sequence of each phase current of the distribution measurement terminal downstream of the head end of the 10kV line are correct; ② If the qualified standards are not met, the phase sequence of each phase current of the power distribution measurement terminal needs to be adjusted and corrected; The adjustment and correction methods are: When the phase angle of the A-phase current at the distribution measurement terminal at the head end is used as the reference, the difference The smallest phase is marked as phase A, and then the other two phases are adjusted in sequence according to the positive phase sequence requirements and marked as phase B and phase C; When the phase angle of the B phase current at the distribution measurement terminal at the head end is used as the reference, the difference The smallest phase is marked as phase B, and then the other two phases are adjusted in sequence according to the positive phase sequence requirements and marked as phase C and phase A; When the phase angle of the C phase current at the distribution measurement terminal at the head end is used as the reference, the difference The smallest phase is marked as phase C, and then the phases of the other two phases are adjusted in sequence according to the positive phase sequence requirements and marked as phase A and phase B.

2. The method for checking the phase sequence of the current at the distribution measurement terminal by comparing the phase difference of the line current as claimed in claim 1 is characterized in that: The power factor angle of each 10kV line breaker interval of the substation in step 1) for: In formula (1), P is the active power of each 10 kV line breaker bay of the substation, Q is the reactive power of each 10 kV line breaker bay of the substation; φ represents phase A, phase B or phase C; i is 1 to n, representing the i-th line; the direction of P and Q is defined as follows: the line load P and Q are set to be sent from the substation bus to the line in the positive direction.

3. The method for checking the phase sequence of the current at the distribution measurement terminal by comparing the phase difference of the line current as claimed in claim 1 is characterized in that: Steps 1) to 2) require that the current of a phase of the reference line be used as the reference to calculate the current of phase A of the jth distribution measurement terminal on the i-th line of the 10kV line. Phase B current Phase C current The current phase angle The calculation formula is: (2) In the formula, The current of phase A at the terminal of the jth distribution unit of the i-th line is measured Phase B current Phase C current The phase angle, φ represents phase A, phase B or phase C, Indicates the reference line A phase current Or B phase current or C phase current Indicates the A-phase current flowing through the j-th distribution measurement terminal of the i-th line Or B phase current or C phase current i represents the i-th line, i is 1 to n; j represents the j-th group of distribution measurement terminals on the i-th line, j is 1 to m; And, step 1) requires the substation bus three-phase voltage As the reference, calculate the A phase current of the first distribution measurement terminal of the ith line on the 10kV line Phase B current Phase C current The current phase angle The calculation formula is: (3) In the formula, Indicates the first distribution measurement terminal A phase of the i-th line Phase B Phase C current The phase angle, Indicates the three-phase voltage of the 10kV busbar of the substation 4. The method for checking the phase sequence of the current at the power distribution measurement terminal by comparing the phase difference of the line current as claimed in claim 1, characterized in that: Step 1) calculates the power factor angle of the reference line interval Based on the power factor angle of each 10kV line interval in the substation, the power factor angle of each 10kV line interval in the substation is calculated in real time. Power factor angle from the reference line The angle difference between 5. The method for checking the phase sequence of the current at the distribution measurement terminal by comparing the phase difference of the line current as claimed in claim 1, characterized in that: In step 1), the three-phase current phase angle of the distribution measurement terminal at the head end of each 10kV line interval of the substation is calculated in real time based on the current of a certain phase of the distribution measurement terminal at the head end of the reference line, or based on the three-phase voltage of the substation busbar. The phase angle of the three-phase current at the power distribution measurement terminal at the head end of the reference line The angle difference between 6. The method for checking the phase sequence of the current at the distribution measurement terminal by comparing the line current phase difference as claimed in claim 1, characterized in that: The comparison of the phase difference angle of the three-phase current of the distribution measurement terminal at the head end of each 10kV line in step 1) (4) The power factor angle difference of 10kV line interval corresponding to the substation The difference between these two angles The calculation formula is: The calculated two angle differences for each line and The difference between The acceptance standard is ±20°.

7. The method for checking the phase sequence of the current at the distribution measurement terminal by comparing the phase difference of the line current as claimed in claim 1, characterized in that: In step 2), the current of a certain phase of the terminal is measured by the power distribution at the head end of the corresponding reference line. The current phase As a benchmark, the phase angle of a phase current at the jth distribution measurement terminal of the i-th line downstream of a 10kV line is The phase angle of a phase current at the distribution measurement terminal at the head end The difference between these two angles The calculation formula is: Calculated angle difference The acceptance standard is ±20°.

8. The method for checking the phase sequence of the current at the distribution measurement terminal by comparing the phase difference of the line current as claimed in claim 1, characterized in that: The voltage level applicable to distribution lines is 6kV~35kV. The grounding methods used in 6kV~35kV systems are ungrounded system, arc suppression coil grounding system, and low resistance grounding system.

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