Wireless synchronous measurement method and system for resistive current of zinc oxide arrester

Abstract

The invention relates to the technical field of lightning arrester measurement, in particular to a zinc oxide lightning arrester resistive current wireless synchronous measurement method and system, and the method comprises the steps: collecting A, B and C phase leakage current signals of a to-be-measured zinc oxide lightning arrester and a power grid A phase voltage signal; a time synchronization instruction is sent to the A, B and C phase current acquisition units and the voltage acquisition unit through the aggregation node; the A-phase current acquisition unit sends a second time synchronization instruction to the B-phase current acquisition unit, the C-phase current acquisition unit and the voltage acquisition unit according to the time synchronization result; sampling according to the result of the second time synchronization; and performing wireless synchronous measurement on the resistive current of the zinc oxide arrester according to the sampled data framing, the A-phase leakage current signal, the B-phase leakage current signal, the C-phase leakage current signal and the A-phase voltage signal of the power grid. The sink node, the A-phase current acquisition unit, the B-phase current acquisition unit, the C-phase current acquisition unit and the voltage acquisition unit perform wireless transmission data synchronous acquisition; the problem of insulation damage or electromagnetic interference caused by traditional wired connection is avoided, and the operation risk in a high-voltage environment is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of lightning arrester measurement, and particularly relates to a method for wireless synchronous measurement of resistive current of zinc oxide lightning arrester and a system for wireless synchronous measurement of resistive current of zinc oxide lightning arrester. Background Art

[0002] A lightning arrester is an important device used to protect power equipment and power systems, and its main function is to discharge overvoltage to the ground during lightning strikes. The leakage current refers to the current flowing through the lightning arrester under normal operating conditions, and its magnitude is closely related to the operating state of the lightning arrester. An excessive leakage current of the lightning arrester can lead to faults such as overheating and burnout of the equipment, and may even cause accidents such as fires in severe cases.

[0003] In recent years, due to the wide distribution of transmission lines, zinc oxide lightning arresters are installed at the cable terminals to protect high-voltage cables, and most of them are located outdoors far from the substation. The reference phase signal cannot be connected to the lightning arrester status measurement equipment of the overhead transmission line by wire. As a result, the aging phenomenon of zinc oxide lightning arresters cannot be detected in time, which seriously affects the service life and safety of zinc oxide lightning arresters, and may endanger the safety of the power system.

[0004] The requirement for power supply reliability has changed the lightning arrester test from the original power-off pre-test to the live test, and the live test work has been strengthened. The live test of zinc oxide lightning arresters judges the aging and moisture absorption of the lightning arrester valve disc by measuring the resistive component in the leakage current of the lightning arrester valve disc without power interruption. The current live test method for zinc oxide lightning arresters is mainly to introduce the voltage signal and current signal of the lightning arrester collected through a signal cable into a measurement device to obtain the resistive current of the lightning arrester. Each measurement requires on-site wiring, with a large workload. For example, the invention patent with the publication number CN118707223A discloses a method for monitoring the resistive current of a transmission cable lightning arrester, and the invention patent with the publication number CN114236297A discloses an on-line monitoring system for lightning arresters.

[0005] Regarding wireless measurement, relevant prior arts have also been disclosed. For example, the invention patent with the publication number CN118033350B discloses a system and method for wireless acquisition and monitoring of lightning arrester operating parameters. It realizes digital intelligent status monitoring of line lightning arresters through wireless acquisition and monitoring of the operating parameters of in-station lightning arresters, improves the analysis and judgment ability of the operating status of lightning arresters, and provides strong support for preventive maintenance and fault handling. However, it does not consider the time error caused by the delay of micro-power wireless communication, which results in the inability to guarantee the accuracy of the leakage current measurement of the lightning arrester. Moreover, this application does not give a specific implementation scheme for the resistive current of the zinc oxide lightning arrester, but only gives a rough analysis and judgment method for the operating status of the lightning arrester. Summary of the Invention

[0006] Object of the Invention: In order to overcome the deficiencies of the prior art, the present invention provides a method for wireless synchronous measurement of resistive current of zinc oxide arresters, which solves the problem of low accuracy of leakage current measurement of arresters caused by the delay of micro-power wireless communication. The present invention also provides a system for wireless synchronous measurement of resistive current of zinc oxide arresters.

[0007] Technical Solution: According to the first aspect of the present invention, there is provided a method for wireless synchronous measurement of resistive current of zinc oxide arresters, which includes the following steps:

[0008] An on-line monitoring device of a zinc oxide arrester is used to collect leakage current signals corresponding to zinc oxide arresters on the A-phase, B-phase, and C-phase lines and the A-phase voltage signal of the power grid. Among them, the on-line monitoring device of the zinc oxide arrester is installed on the power grid and includes a convergence node, a voltage acquisition unit, and A-phase, B-phase, and C-phase current acquisition units. The A-phase, B-phase, and C-phase current acquisition units are respectively connected to zinc oxide arresters on the A-phase, B-phase, and C-phase lines and are respectively used to collect leakage current signals to be measured corresponding to zinc oxide arresters on the A-phase, B-phase, and C-phase lines; the voltage acquisition unit is used to collect the voltage signal on the A-phase line of the power grid. The convergence node is wirelessly communicatively connected to the voltage acquisition unit and the A-phase, B-phase, and C-phase current acquisition units and sends relevant instructions;

[0009] The convergence node sends a first time synchronization instruction to the A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit, and completes the first time synchronization of the A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit;

[0010] The A-phase current acquisition unit sends a second time synchronization instruction to the B-phase and C-phase current acquisition units and the voltage acquisition unit according to the time after the first time synchronization. The B-phase and C-phase current acquisition units and the voltage acquisition unit reset the count value of their own counters to zero and start counting from zero;

[0011] After the first time synchronization and the second time synchronization are completed, the convergence node stores the sampling values of the leakage current signals to be measured of the A-phase, B-phase, and C-phase and the voltage signal of the A-phase of the power grid and the current value of the current counter in their respective sampling data buffer areas;

[0012] The convergence node performs wireless synchronous measurement of the resistive currents corresponding to the leakage current signals to be measured of the A-phase, B-phase, and C-phase and the voltage signal of the A-phase of the power grid according to the sampling data group frame obtained from the sampling values and the corresponding counter values.

[0013] Further, it includes:

[0014] When performing the first time synchronization for the A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit, it specifically includes:

[0015] The aggregation node sends a first time synchronization instruction to the A-phase current acquisition unit and records the time T1 at the moment when the first time synchronization instruction is sent;

[0016] After receiving the first time synchronization instruction sent by the aggregation node, the A-phase current acquisition unit performs message time synchronization response to the first time synchronization instruction. Among them, the time T2 when the first time synchronization instruction is received and the time T3 at the moment when the response message is sent are included in the response message for time synchronization;

[0017] The aggregation node receives the time synchronization response message of the A-phase current acquisition unit and records the reception time T4, and then obtains the time error during information reception between the aggregation node and the A-phase current acquisition unit due to the delay of the micro-power wireless communication;

[0018] Perform the operation of sending and receiving the first time synchronization instruction multiple times to obtain T1, T2, T3, and T4 under different numbers of times, calculate the time error multiple times to obtain multiple time error values, and calculate the average value of the multiple time error values to obtain the average time error ΔT A ;

[0019] The aggregation node forms an accurate time synchronization message by combining the current time T5 and the average time error, and sends an accurate time synchronization instruction to the A-phase current acquisition unit;

[0020] The aggregation node sequentially performs the first time synchronization for the B-phase, C-phase current acquisition units and the voltage acquisition unit.

[0021] Furthermore, it includes:

[0022] Perform the operation of sending and receiving the first time synchronization instruction multiple times to obtain T1, T2, T3, and T4 under different numbers of times, calculate the time error multiple times to obtain multiple time error values, and calculate the average value of the multiple time error values to obtain the average time error ΔT A , which is expressed as:

[0023] ΔT A = avg(ΔT Am );

[0024] ΔT Am =(T 2m -T 1m )-(T 4m -T 3m ) / 2;

[0025] Among them, ΔT Am is the time error value corresponding to the m-th operation of sending and receiving the first time synchronization instruction, T 1mis the time of the first pair command transmission moment in the m-th first pair command transceiver operation, T 2m is the time when the A-phase current acquisition unit receives the first pair command in the m-th first pair command transceiver operation, T 3m is the time of the A-phase current acquisition unit response message transmission moment in the m-th first pair command transceiver operation, T 4m is the time when the aggregation node receives the pair response message of the A-phase current acquisition unit in the m-th first pair command transceiver operation.

[0026] Further, it includes:

[0027] The A-phase current acquisition unit sends a second pair command to the B-phase and C-phase current acquisition units and the voltage acquisition unit according to the time after the first pair. It also includes:

[0028] represents the count values of the counters inside the A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit before receiving the synchronous acquisition command in the next synchronization period.

[0029] Further, it includes:

[0030] The aggregation node stores the sampling values of the leakage current signals to be measured of the A-phase, B-phase, and C-phase and the voltage signal of the grid A-phase and the current counter value in their respective sampling data buffers each time. The set sampling frequency is:

[0031] The A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit start an A / D sampling every M timers, that is, start an A / D sampling every M*N, where N is the counter period, and store the signal sampling values and counter values.

[0032] Further, it includes:

[0033] After completing the first pair and the second pair, the aggregation node stores the sampling values of the leakage current signals to be measured of the A-phase, B-phase, and C-phase and the voltage signal of the grid A-phase and the current counter value in their respective sampling data buffers each time. After that, it also includes:

[0034] The aggregation node sends a synchronous acquisition command to the A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit. The A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit frame and transmit the sampling data in their respective sampling data buffers that contain the sampling time point Q and the sampling data before the Q point to the aggregation node. Among them, the synchronous acquisition command contains the time scale information of the sampling time point Q, that is, when sending the synchronous acquisition command, the time scale of the counter is the sampling time point Q.

[0035] Further, it includes:

[0036] The aggregation node wirelessly synchronously measures the resistive current corresponding to the leakage current signals to be measured of phases A, B, and C and the voltage signal of phase A of the power grid by framing the sampling data obtained according to the sampling values and the values of the corresponding counters. Specifically, it includes:

[0037] Obtain the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signals to be measured corresponding to phases A, B, and C and the voltage signal of phase A of the power grid by framing the sampling data obtained according to the sampling values;

[0038] Calculate the amplitude, phase angle, and effective value of the k-th harmonic corresponding to the measurement, and the phase angle of the voltage signal of phase A of the power grid according to the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signals to be measured of phases A, B, and C and the voltage signal of phase A of the power grid. Among them, the voltage signal of phase A of the power grid is used as the reference phase signal of the on-line monitoring device of the zinc oxide arrester;

[0039] Obtain the phase angle differences between the leakage current signals to be measured of phases A, B, and C and the reference phase signal according to the phase angles of the leakage current signals to be measured of phases A, B, and C and the phase angle of the voltage signal of phase A of the power grid;

[0040] Obtain the fundamental wave resistive current, third harmonic resistive current, and dielectric loss factor of the leakage current signals of phases A, B, and C according to the phase angle differences;

[0041] Furthermore, it includes:

[0042] The obtaining of the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signals to be measured corresponding to phases A, B, and C and the voltage signal of phase A of the power grid by framing the sampling data obtained according to the sampling values includes:

[0043] The Fourier coefficients of the fundamental wave component and harmonic components of the leakage current signal of phase A are respectively expressed as:

[0044]

[0045] where, a kn is the real part of the Fourier coefficients of the fundamental wave and harmonic components of the leakage current signal of phase A of the zinc oxide arrester to be measured, b kn is the imaginary part of the Fourier coefficients of the fundamental wave and harmonic components of the leakage current signal of phase A of the zinc oxide arrester to be measured, T is the sampling period, I A (n) is the n-th A / D sampling value of the leakage current signal of phase A, n = 1, 2,..., 127, N = 128, and k is a positive integer.

[0046] Furthermore, it includes:

[0047] Calculating the amplitude, phase angle, and effective value of the k-th harmonic corresponding to the measured value, and the phase angle of the grid A-phase voltage signal according to the Fourier coefficients of the fundamental wave component and harmonic component of the leakage current signals to be measured in phases A, B, and C and the grid A-phase voltage signal, including:

[0048] The amplitude, phase angle, and effective value of the k-th harmonic of the phase A leakage current signal are respectively expressed as:

[0049]

[0050] Where, I Ak is the amplitude of the k-th harmonic of the phase A leakage current signal, φ Ak is the phase angle of the k-th harmonic of the phase A leakage current signal, is the effective value of the k-th harmonic of the phase A leakage current signal;

[0051] The phase angle of the grid A-phase voltage signal is expressed as:

[0052] φ UAk = arctg(b UAkn a UAkn );

[0053] Where, b UAkn is the imaginary part of the Fourier coefficient of the fundamental wave and harmonic components of the grid A-phase voltage signal, a UAkn is the real part of the Fourier coefficient of the fundamental wave and harmonic components of the grid A-phase voltage signal.

[0054] Furthermore, it includes:

[0055] Obtaining the fundamental wave resistive current, third harmonic resistive current, and dielectric loss factor of the leakage current signals in phases A, B, and C according to the phase angle difference, including:

[0056] The fundamental wave resistive current, third harmonic resistive current, and dielectric loss factor of the phase A leakage current signal are respectively expressed as:

[0057]

[0058] Where, I A1r is the fundamental wave resistive current of the phase A leakage current signal, I A3r is the third harmonic resistive current of the phase A leakage current signal, tgσ A is the dielectric loss factor of the phase A leakage current signal, φ IA1 is the phase angle difference between the phase A leakage current signal and the grid A-phase voltage signal, φ IA1 = φ A1 - φ UA1 , φ UA1 That is, φUAk where the phase angle corresponding to k = 1 is φ A1 is φ Ak the phase angle corresponding to k = 1.

[0060] On the other hand, the present invention also provides a wireless synchronous measurement system for resistive current of a zinc oxide lightning arrester. The system includes:

[0061] A signal acquisition module, which is used to collect leakage current signals corresponding to zinc oxide lightning arresters on the A-phase, B-phase, and C-phase lines and the A-phase voltage signal of the power grid by using an on-line monitoring device of the zinc oxide lightning arrester. Among them, the on-line monitoring device of the zinc oxide lightning arrester is installed on the power grid and includes a convergence node, a voltage acquisition unit, and A-phase, B-phase, and C-phase current acquisition units. The A-phase, B-phase, and C-phase current acquisition units are respectively connected to the zinc oxide lightning arresters on the A-phase, B-phase, and C-phase lines and are respectively used to collect the to-be-measured leakage current signals corresponding to the zinc oxide lightning arresters on the A-phase, B-phase, and C-phase lines; the voltage acquisition unit is used to collect the voltage signal on the A-phase line of the power grid, and the convergence node is wirelessly communicatively connected to the voltage acquisition unit and the A-phase, B-phase, and C-phase current acquisition units and sends relevant instructions;

[0062] A first time synchronization module, which is used to send a first time synchronization instruction to the A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit by using the convergence node and complete the first time synchronization of the A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit;

[0063] A second time synchronization module, which is used to send a second time synchronization instruction to the B-phase and C-phase current acquisition units and the voltage acquisition unit by using the A-phase current acquisition unit according to the time after the first time synchronization. The B-phase and C-phase current acquisition units and the voltage acquisition unit reset the count value of their own counters to zero and start counting from zero;

[0064] A data sampling module, which is used to store the sampling values of the to-be-measured leakage current signals of the A-phase, B-phase, and C-phase and the voltage signal of the A-phase of the power grid and the current value of the current counter in their respective sampling data buffers after the first time synchronization and the second time synchronization are completed;

[0065] A synchronous measurement module, which is used to wirelessly synchronously measure the resistive current corresponding to the to-be-measured leakage current signals of the A-phase, B-phase, and C-phase and the voltage signal of the A-phase of the power grid by using the sampling data frame obtained by the convergence node according to the sampling value and the value of the corresponding counter.

[0066] Furthermore, it includes:

[0067] The system further includes a synchronous acquisition module, which is arranged between the data sampling module and the synchronous measurement module and is used for: sending a synchronous acquisition instruction to the A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit by using the aggregation node, and the A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit frame and transmit the sampling data in their respective sampling data buffers that include the sampling time point Q and the sampling data before the point Q to the aggregation node, wherein the synchronous acquisition instruction includes the time scale information of the sampling time point Q, that is, when the synchronous acquisition instruction is sent, the time scale of the counter is the sampling time point Q.

[0068] Finally, the present invention also provides a computer-readable storage medium storing a computer program, characterized in that when the computer program is executed by a processor, it implements the method for wireless synchronous measurement of the resistive current of a zinc oxide arrester as described above.

[0069] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0070] (1) The traditional measurement method of zinc oxide arresters is wired and requires wiring, with complex installation. In the method of the present invention, wireless data synchronous acquisition is adopted between the aggregation node, the A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit of the zinc oxide arrester, avoiding the problems of insulation damage or electromagnetic interference that may be caused by traditional wired connections, reducing the operation risk in a high-voltage environment, being convenient for on-site installation, and adapting to harsh environments.

[0071] (2) The present invention does not require a GPS or Beidou satellite timing module, overcomes the problem that the PPS pulse may fail due to weather, faults, and other factors in the GPS or Beidou module, and only realizes synchronous sampling and measurement of each acquisition unit for the status monitoring of the zinc oxide arrester through a high-precision crystal oscillator and micro-power wireless communication inside the on-line monitoring device of the zinc oxide arrester, accurately capturing the phase and amplitude changes of the leakage current of the arrester, and saving hardware costs.

[0072] (3) The present invention collects the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured and the grid phase A voltage signal, and then sends a first time synchronization instruction to the current acquisition units and voltage acquisition units of phases A, B, and C of the zinc oxide arrester to be measured through the aggregation node to achieve the first time synchronization. The current acquisition unit of phase A of the zinc oxide arrester to be measured sends a second time synchronization instruction to the current acquisition units and voltage acquisition units of phases B and C of the zinc oxide arrester to be measured according to the result of the first time synchronization to achieve the second time synchronization, and samples according to the result of the second time synchronization. The sampling results and the counter values are stored in their respective sampling data buffers. When the aggregation node sends a synchronous acquisition instruction, each acquisition unit frames and transmits its sampling data to the aggregation node; finally, the aggregation node wirelessly synchronously measures the resistive current of the zinc oxide arrester to be measured according to the sampled data frame, the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured, and the grid phase A voltage signal. Thus, wireless synchronous measurement can be performed, and due to the rough time synchronization and precise time synchronization operations, the measurement of the resistive current of the zinc oxide arrester is more accurate. Therefore, the aging of the zinc oxide arrester can be accurately identified in a timely manner, thereby improving the service life of the zinc oxide arrester and the safety of the power system. Description of the Drawings

[0073] Figure 1 It is a flowchart of the method for wireless synchronous measurement of the resistive current of the zinc oxide arrester according to Embodiment 1 of the present invention;

[0074] Figure 2 It is a flowchart of the method for wireless synchronous measurement of the resistive current of the zinc oxide arrester according to Embodiment 2 of the present invention;

[0075] Figure 3 It is a schematic diagram of the on-line monitoring device of the zinc oxide arrester according to Embodiment 2 of the present invention;

[0076] Figure 4 It is a schematic diagram of the count value of the counter before sending the second time synchronization instruction according to Embodiment 2 of the present invention;

[0077] Figure 5 It is a schematic diagram of the count value of the counter after sending the second time synchronization instruction according to Embodiment 2 of the present invention;

[0078] Figure 6 It is a schematic diagram of the sampled data frame being transmitted to the aggregation node according to Embodiment 2 of the present invention;

[0079] Figure 7 It is a schematic diagram of the wireless synchronous measurement system of the resistive current of the zinc oxide arrester according to Embodiment 3 of the present invention;

[0080] Figure 8 It is a flowchart of the wireless synchronous measurement of the resistive current of the zinc oxide arrester to be measured according to Embodiment 2 of the present invention. Specific Embodiment

[0081] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0082] Embodiment 1

[0083] As Figure 1 shown, the embodiment of the present invention provides a method for wireless synchronous measurement of resistive current of a zinc oxide lightning arrester. The method includes the following steps:

[0084] S1. An on-line monitoring device of a zinc oxide lightning arrester is used to collect leakage current signals corresponding to the zinc oxide lightning arresters on the A-phase, B-phase, and C-phase lines and the A-phase voltage signal of the power grid. Among them, the on-line monitoring device of the zinc oxide lightning arrester is installed on the power grid and includes a convergence node, a voltage acquisition unit, and A-phase, B-phase, and C-phase current acquisition units. The A-phase, B-phase, and C-phase current acquisition units are respectively connected to the zinc oxide lightning arresters on the A-phase, B-phase, and C-phase lines and are respectively used to collect the leakage current signals to be measured corresponding to the zinc oxide lightning arresters on the A-phase, B-phase, and C-phase lines; the voltage acquisition unit is used to collect the voltage signal on the A-phase line of the power grid. The convergence node is wirelessly communicatively connected to the voltage acquisition unit and the A-phase, B-phase, and C-phase current acquisition units and sends relevant instructions;

[0085] S2. The convergence node sends a first time synchronization instruction to the A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit and completes the first time synchronization of the A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit;

[0086] S3. The A-phase current acquisition unit sends a second time synchronization instruction to the B-phase and C-phase current acquisition units and the voltage acquisition unit according to the result of the first time synchronization, realizing the micro time base synchronization of the A-phase current acquisition unit to the B-phase and C-phase current acquisition units and the voltage acquisition unit;

[0087] S4. The A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit perform sampling according to the result of the second time synchronization and store the sampling values and counter values of the leakage current signals to be measured of the A-phase, B-phase, and C-phases and the voltage signal of the A-phase of the power grid in their respective sampling data buffer areas;

[0088] S5. The convergence node performs wireless synchronous measurement of the resistive current corresponding to the leakage current signals to be measured of the A-phase, B-phase, and C-phases and the voltage signal of the A-phase of the power grid according to the sampling data framed by the sampling values.

[0089] Example 2

[0090] Based on Example 1, the present application provides Example 2, which further includes between steps S4 and S5:

[0091] Step S41: The aggregation node sends a synchronous acquisition instruction to the A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit. The A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit frame and transmit the sampling data in their respective sampling data buffers that include the sampling time point Q and the sampling data before point Q to the aggregation node. Among them, the synchronous acquisition instruction includes the time scale information of the sampling time point Q, that is, when sending the synchronous acquisition instruction, the time scale of the counter is the sampling time point Q.

[0092] Here, the present application makes a specific description of Example 2, including:

[0093] As Figure 2 shown, the method for wireless synchronous measurement of resistive current of zinc oxide arresters in the embodiments of the present invention includes the following steps:

[0094] S1: According to the on-line monitoring device of the zinc oxide arrester, the leakage current signals of the A-phase, B-phase, and C-phase of the zinc oxide arrester to be measured and the A-phase voltage signal of the power grid are collected. Among them, the on-line monitoring device of the zinc oxide arrester includes an aggregation node, A-phase, B-phase, and C-phase current acquisition units of the zinc oxide arrester, and a voltage acquisition unit.

[0095] In an embodiment of the present invention, as Figure 3 shown, the A-phase, B-phase, and C-phase current acquisition units of the zinc oxide arrester to be measured with microampere current sensors can be clamped on the connection lead between the zinc oxide arrester body and the lightning strike counter. Therefore, it is used to collect the leakage current signals of the A-phase, B-phase, and C-phase of the zinc oxide arrester to be measured. At the same time, the voltage acquisition unit of the zinc oxide arrester can also be connected to the A-phase voltage line on the transmission line through a voltage transformer to collect the A-phase voltage signal of the power grid and use the A-phase voltage signal of the power grid as the reference phase signal of the on-line monitoring device of the zinc oxide arrester.

[0096] S2: The aggregation node sends a first time synchronization instruction to the A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit of the zinc oxide arrester to be measured to achieve the first time synchronization of the aggregation node to the A-phase, B-phase, and C-phase current acquisition units and the voltage acquisition unit of the zinc oxide arrester to be measured.

[0097] In an embodiment of the present invention, the aggregation node performs wireless communication with other units and can implement relevant data processing. Specifically: after the aggregation node, the current acquisition units of phases A, B, and C of the zinc oxide arrester to be measured, and the voltage acquisition unit are powered on and running, the aggregation node can send a first time synchronization instruction to the current acquisition units of phases A, B, and C of the zinc oxide arrester to be measured and the voltage acquisition unit every 5 minutes to achieve time synchronization at the millisecond level. Among them, the aggregation node, the current acquisition units of phases A, B, and C of the zinc oxide arrester to be measured, and the voltage acquisition unit all have the micro-power wireless communication function, and communication can be carried out between the aggregation node, the current acquisition units of phases A, B, and C of the zinc oxide arrester to be measured, and the voltage acquisition unit through micro-power wireless.

[0098] Among them, the first time synchronization of the aggregation node to the current acquisition units of phases A, B, and C of the zinc oxide arrester to be measured and the voltage acquisition unit may specifically include:

[0099] The aggregation node sends a first time synchronization instruction to the current acquisition unit of phase A of the zinc oxide arrester to be measured, and the aggregation node records the time when the first time synchronization instruction is sent as T1; after receiving the first time synchronization instruction sent by the aggregation node, the current acquisition unit of phase A of the zinc oxide arrester to be measured performs message time synchronization response to the first time synchronization instruction. Among them, the message of the time synchronization response contains the time T2 when the first time synchronization instruction is received and the time T3 when the response message is sent; the aggregation node receives the time synchronization response message of the current acquisition unit of phase A of the zinc oxide arrester to be measured and records the reception time T4;

[0100] Calculate the time error ΔT between the aggregation node and the current acquisition unit of phase A of the zinc oxide arrester to be measured caused by the delay of micro-power wireless communication through the aggregation node A1 , where the time error ΔT A1 The calculation formula is:

[0101] ΔT A1 =(T2 - T1)-(T4 - T3) / 2 (1)

[0102] Perform multiple calculations on the time error ΔT A1 to obtain multiple time errors ΔT Am , in this embodiment, that is, perform information transmission multiple times to obtain T1, T2, T3, and T4 under different numbers of times, and then the aggregation node can perform 10 operations on the time error ΔT A1 , where m is a positive integer greater than or equal to 1 and less than or equal to 10; calculate the average value of multiple time errors ΔT Am to obtain the average time error ΔT between the aggregation node and the current acquisition unit of phase A of the zinc oxide arrester to be measured A , where the average time error ΔT A The calculation formula is:

[0103] ΔT A = avg(ΔT Am ); (2)

[0104] where avg is the average value function.

[0105] Specifically, in this embodiment, the operation of sending and receiving the first pair of time synchronization commands is performed multiple times to obtain T1, T2, T3, and T4 under different numbers of times, and the time error is calculated multiple times to obtain multiple time error values. The average value of the multiple time error values is obtained to obtain the average time error ΔT A , which is expressed as:

[0106] ΔT A = avg(ΔT Am ); (3)

[0107] ΔT Am = (T 2m - T 1m ) - (T 4m - T 3m ) / 2; (4)

[0108] where ΔT Am is the time error value corresponding to the m-th operation of sending and receiving the first pair of time synchronization commands, T 1m is the time at which the first pair of time synchronization commands is sent during the m-th operation of sending and receiving the first pair of time synchronization commands, T 2m is the time when the A-phase current acquisition unit receives the first pair of time synchronization commands during the m-th operation of sending and receiving the first pair of time synchronization commands, T 3m is the time at which the A-phase current acquisition unit sends the response message during the m-th operation of sending and receiving the first pair of time synchronization commands, T 4m is the time when the aggregation node receives the time synchronization response message of the A-phase current acquisition unit during the m-th operation of sending and receiving the first pair of time synchronization commands.

[0109] In this embodiment, the aggregation node forms an accurate time synchronization message by combining the current time T5 and the average time error ΔT A and sends an accurate time synchronization command to the A-phase current acquisition unit of the zinc oxide arrester to be measured. The time tag of the accurate time synchronization command is (T5 + ΔT A );

[0110] After the A-phase current acquisition unit of the zinc oxide arrester to be measured receives the accurate time synchronization command from the aggregation node, it modifies its own time;

[0111] The aggregation node performs time synchronization on the B-phase and C-phase current acquisition units and the voltage acquisition unit of the zinc oxide arrester to be measured in sequence according to the above steps.

[0112] The operation process of synchronizing the current acquisition units and voltage acquisition units of the B and C phases of the zinc oxide lightning arrester to be measured is the same as the operation process of synchronizing the current acquisition unit of the A phase of the zinc oxide lightning arrester to be measured.

[0113] S3 The phase A current acquisition unit of the zinc oxide lightning arrester to be measured sends a second timing instruction to the phase B and C current acquisition units and voltage acquisition units of the zinc oxide lightning arrester to be measured according to the result of the first timing, so as to realize the second timing of the phase A current acquisition unit of the zinc oxide lightning arrester to be measured on the phase B and C current acquisition units and voltage acquisition units of the zinc oxide lightning arrester to be measured.

[0114] In one embodiment of the present invention, the A-phase current acquisition unit of the zinc oxide arrester to be measured can perform time base micro-synchronization on the B-phase and C-phase current acquisition units of the zinc oxide arrester to be measured every 5 seconds, and the timing accuracy can reach 10uS level.

[0115] Among them, when the A-phase current acquisition unit of the zinc oxide lightning arrester to be measured is the second pair of the B-phase and C-phase current acquisition units and the voltage acquisition unit to be measured, it can specifically include: after the A-phase, B-phase and C-phase current acquisition units and the voltage acquisition units of the zinc oxide lightning arrester to be measured are powered on for the first time, the built-in counters of the A-phase, B-phase and C-phase current acquisition units and the voltage acquisition units of the zinc oxide lightning arrester to be measured start counting from 0 respectively;

[0116] When the A-phase current acquisition unit of the zinc oxide lightning arrester to be measured sends the second pair of time instructions to the B-phase and C-phase current acquisition units and the voltage acquisition units of the zinc oxide lightning arresters to be measured, the B-phase and C-phase current acquisition units and the voltage acquisition units of the zinc oxide lightning arresters to be measured reset the count values of their own counters to zero.

[0117] Specifically, since the hardware inside the A, B, and C phase current acquisition units and voltage acquisition units of each zinc oxide lightning arrester to be measured uses a high-precision crystal oscillator of ±2ppm, a fixed timing interval can be set through the timer integrated in the hardware CPU (Central Processing Unit), thereby realizing a counter Ticks, where the timing interval is less than or equal to 10uS.

[0118] In order to facilitate the following description, the counters in the current acquisition unit and voltage acquisition unit of the A, B, and C phases of the zinc oxide arrester to be measured can be represented by TicksA, TicksB, TicksC, and TicksD, respectively, and the count values of the counters can be represented by N A 、N B 、N C and N D express.

[0119] like Figure 4As shown, after the current acquisition units and voltage acquisition units of the zinc oxide arresters A, B, and C to be measured are powered on for the first time, TicksA, TicksB, TicksC, and TicksD start counting from 0 respectively. Due to the difference in the power-on time, there will be asynchronous counting for TicksA, TicksB, TicksC, and TicksD, and the counted values of TicksA, TicksB, TicksC, and TicksD may all be different. Among them, PO represents the power-on time of the current acquisition units and voltage acquisition units of the zinc oxide arresters A, B, and C to be measured.

[0120] As Figure 5 shown, when the current acquisition unit of phase A of the zinc oxide arrester to be measured sends the second time synchronization instruction to the current acquisition units and voltage acquisition units of phases B and C of the zinc oxide arrester to be measured, all the acquisition units that receive the second time synchronization instruction reset the counted value of their own counter to zero, that is, Ticks starts counting from 0.

[0121] In this embodiment, Figure 5 it is expressed that after the current acquisition units and voltage acquisition units of the zinc oxide arresters A, B, and C to be measured are powered on for the first time, TicksA, TicksB, TicksC, and TicksD start counting from 0 respectively. Due to the difference in the power-on time, there will be asynchronous counting for TicksA, TicksB, TicksC, and TicksD, and the counted values of TicksA, TicksB, TicksC, and TicksD may all be different. Among them, PO represents the power-on time of the current acquisition units and voltage acquisition units of the zinc oxide arresters A, B, and C to be measured. BSI represents the second time synchronization instruction. When the current acquisition unit of phase A of the zinc oxide arrester to be measured sends the second time synchronization instruction to the current acquisition units and voltage acquisition units of phases B and C of the zinc oxide arrester to be measured, all the acquisition units that receive the second time synchronization instruction reset the counted value of their own counter to zero, that is, Ticks starts counting from 0. Among them, N’ A 、N’ B 、N’ C 、N’ D can represent the counted values of the counters inside the current acquisition units and voltage acquisition units of the zinc oxide arresters A, B, and C to be measured before receiving the second time synchronization instruction in the next synchronization period. This figure shows that the second time synchronization instruction can be used to achieve synchronous counting of TicksA, TicksB, TicksC, and TicksD of the current acquisition units and voltage acquisition units of the zinc oxide arresters A, B, and C to be measured, and then achieve accurate synchronous timing.

[0122] For the current acquisition units and voltage acquisition units of phases A, B, and C of the zinc oxide lightning arrester to be measured in S4, according to the result of the second time synchronization, A / D sampling is performed every n counters, and the sampling values and counter values are stored in their respective sampling data buffers.

[0123] In a specific embodiment of the present invention, after the first time synchronization and the second time synchronization are completed, the current acquisition units and voltage acquisition units of phases A, B, and C of the zinc oxide lightning arrester to be measured can start A / D sampling every 15 Ticks. That is to say, if the period of the counter is 10 μs, then the current acquisition units and voltage acquisition units of phases A, B, and C of the zinc oxide lightning arrester to be measured can start A / D sampling every 150 μs, sample 1 point at a time, and store the sampling values and counter values.

[0124] S41 The aggregation node sends a synchronous acquisition instruction to the current acquisition units and voltage acquisition units of phases A, B, and C of the zinc oxide lightning arrester to be measured. As Figure 6 shown, the current acquisition units and voltage acquisition units of phases A, B, and C of the zinc oxide lightning arrester to be measured frame and transmit 127 sampling data groups before the sampling time point Q and including the sampling time point Q in their respective sampling data buffers to the aggregation node. Among them, the synchronous acquisition instruction includes the time scale information of the sampling time point Q, that is, when the synchronous acquisition instruction is sent, the time scale of the counter is the sampling time point Q.

[0125] In a specific embodiment of the present invention, as Figure 6 shown, when it is necessary for the aggregation node to send a synchronous acquisition instruction to the current acquisition units and voltage acquisition units of phases A, B, and C of the zinc oxide lightning arrester to be measured, the aggregation node can send the synchronous acquisition instruction through micro-power wireless communication. The synchronous acquisition instruction can include the time scale information of the sampling time point Q, that is, Ticks = Q. After receiving the synchronous acquisition instruction from the aggregation node, the current acquisition units and voltage acquisition units of phases A, B, and C of the zinc oxide lightning arrester to be measured frame and transmit the sampling data with the time scale of Q and 127 sampling data groups before the Q point in their respective sampling data buffers to the aggregation node.

[0126] S5 The aggregation node wirelessly synchronously measures the resistive current of the zinc oxide lightning arrester to be measured according to the sampled data frame, the leakage current signals of phases A, B, and C of the zinc oxide lightning arrester to be measured, and the grid phase A voltage signal.

[0127] In this embodiment, preferably, the aggregation node wirelessly synchronously measures the resistive current of the zinc oxide lightning arrester to be measured according to the sampled data frame, the leakage current signals of phases A, B, and C of the zinc oxide lightning arrester to be measured, and the grid phase A voltage signal. As Figure 8 shown, it specifically includes:

[0128] S51 Obtain the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured and the grid phase A voltage signal according to the discrete Fourier transform;

[0129] S52 Calculate the amplitude, phase angle, and effective value of the k-th harmonic of the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured, and the phase angle of the grid phase A voltage signal according to the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured and the grid phase A voltage signal. Among them, the grid phase A voltage signal is used as the reference phase signal of the on-line monitoring device of the zinc oxide arrester;

[0130] S53 Calculate the phase angle differences between the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured and the reference phase signal according to the phase angles of the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured and the grid phase A voltage signal;

[0131] S54 Calculate the fundamental wave resistive current, third harmonic resistive current, and dielectric loss factor of the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured according to the phase angle differences between the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured and the reference phase signal.

[0132] Specifically, in an embodiment of the present invention, taking the leakage current signal of phase A of the zinc oxide arrester to be measured as an example, first, the leakage current signal of phase A of the zinc oxide arrester to be measured can be collected by the phase A current acquisition unit of the zinc oxide arrester to be measured through A / D sampling. Among them, the waveform sequence of the leakage current signal of phase A of the zinc oxide arrester to be measured can be expressed as a periodic signal as follows:

[0133]

[0134] Among them, I A (t) is the leakage current signal of phase A of the zinc oxide arrester to be measured, I A0 is the DC component of the leakage current signal of phase A of the zinc oxide arrester to be measured, I Ak is the amplitude of the k-th harmonic of the leakage current signal of phase A of the zinc oxide arrester to be measured, k is a positive integer, ω is the angular frequency, and φ Ak is the phase angle of the k-th harmonic of the leakage current signal of phase A of the zinc oxide arrester to be measured.

[0135] Among them, the waveform sequences of the leakage current signals of phases B and C of the zinc oxide arrester to be measured and the grid phase A voltage signal are the same as the waveform sequence of the leakage current signal of phase A of the zinc oxide arrester to be measured expressed as a periodic signal, and will not be elaborated here one by one.

[0136] Further, according to the sampling theorem and the discrete Fourier transform, the Fourier coefficients of the fundamental wave components and harmonic wave components of the leakage current signals of the ZnO arresters A, B, and C to be measured and the grid A-phase voltage signal can be obtained.

[0137] In an embodiment of the present invention, taking the leakage current signal of the ZnO arrester A to be measured as an example, the Fourier coefficients of the fundamental wave components and harmonic wave components of the leakage current signal of the ZnO arrester A to be measured can be respectively expressed as:

[0138]

[0139] where a kn is the real part of the Fourier coefficient of the fundamental wave and harmonic wave components of the leakage current signal of the ZnO arrester A to be measured, b kn is the imaginary part of the Fourier coefficient of the fundamental wave and harmonic wave components of the leakage current signal of the ZnO arrester A to be measured, T is the sampling period, I A (n) is the nth A / D sampling value of the leakage current signal of the ZnO arrester A to be measured, n = 1, 2,..., 127, N = 128, and k is a positive integer.

[0140] Among them, the expressions of the Fourier coefficients of the fundamental wave components and harmonic wave components of the leakage current signals of the ZnO arresters B and C to be measured and the grid A-phase voltage signal are the same as those of the Fourier coefficients of the fundamental wave components and harmonic wave components of the leakage current signal of the ZnO arrester A to be measured, and will not be elaborated here one by one.

[0141] Further, according to the Fourier coefficients of the fundamental wave components and harmonic wave components of the leakage current signals of the ZnO arresters A, B, and C to be measured and the grid A-phase voltage signal, calculate the amplitude, phase angle, and effective value of the kth harmonic of the leakage current signals of the ZnO arresters A, B, and C to be measured, and the phase angle of the grid A-phase voltage signal.

[0142] In an embodiment of the present invention, taking the leakage current signal of the ZnO arrester A to be measured as an example, the amplitude, phase angle, and effective value of the kth harmonic of the leakage current signal of the ZnO arrester A to be measured can be respectively expressed as:

[0143]

[0144] where I Ak is the amplitude of the kth harmonic of the leakage current signal of the ZnO arrester A to be measured, φ Ak is the phase angle of the kth harmonic of the leakage current signal of the ZnO arrester A to be measured, is the effective value of the kth harmonic of the leakage current signal of the ZnO arrester A to be measured; the phase angle of the grid A-phase voltage signal is expressed as:

[0145] φ UAk = arctg(b UAkn a UAkn );

[0146] wherein, b UAkn is the imaginary part of the Fourier coefficient of the fundamental wave and harmonic components of the grid A-phase voltage signal, and a UAkn is the real part of the Fourier coefficient of the fundamental wave and harmonic components of the grid A-phase voltage signal.

[0147] In this embodiment, the grid A-phase voltage signal can be used as the reference phase.

[0148] wherein, the expressions of the amplitude, phase angle and effective value of the k-th harmonic of the leakage current signals of the B and C phases of the zinc oxide arrester to be measured are the same as those of the k-th harmonic of the leakage current signal of the A phase of the zinc oxide arrester to be measured, and will not be elaborated here one by one.

[0149] It should be noted that since the grid A-phase voltage signal is used as the reference phase, when performing discrete Fourier transform, only the phase angle of the grid A-phase voltage signal needs to be calculated, and the amplitude and effective value of the grid A-phase voltage signal do not need to be calculated.

[0150] Furthermore, in an embodiment of the present invention, taking the leakage current signal of the A phase of the zinc oxide arrester to be measured as an example, the phase angle of the k-th harmonic of the leakage current signal of the A phase of the zinc oxide arrester to be measured can be subtracted from the phase angle of the k-th harmonic of the grid A-phase voltage signal, and the phase angle difference between the k-th harmonic of the leakage current signal of the A phase of the zinc oxide arrester to be measured and the k-th harmonic of the grid A-phase voltage signal can be obtained, that is, φ IAk = φ Ak - φ UAk , at this time, k = 1 can be substituted to obtain the phase angle difference between the leakage current signal of the A phase of the zinc oxide arrester to be measured and the grid A-phase voltage signal, that is, φ IA1 = φ A1 - φ UA1 .

[0151] Finally, the fundamental wave resistive current, third harmonic resistive current and dielectric loss factor of the leakage current signals of the A, B, and C phases of the zinc oxide arrester to be measured can be calculated according to the phase angle differences of the leakage current signals of the A, B, and C phases of the zinc oxide arrester to be measured and the reference phase signal.

[0152] In an embodiment of the present invention, taking the leakage current signal of the A phase of the zinc oxide arrester to be measured as an example, the fundamental wave resistive current, third harmonic resistive current and dielectric loss factor of the leakage current signal of the A phase of the zinc oxide arrester to be measured can be respectively expressed as:

[0153]

[0154] Among them, I A1r is the fundamental resistive current of the leakage current signal of phase A of the zinc oxide arrester to be measured, and I A3r is the third harmonic resistive current of the leakage current signal of phase A of the zinc oxide arrester to be measured, and tgσ A is the dielectric loss factor of the leakage current signal of phase A of the zinc oxide arrester to be measured.

[0155] Among them, the expressions of the fundamental resistive current, the third harmonic resistive current, and the dielectric loss factor of the leakage current signals of phases B and C of the zinc oxide arrester to be measured are the same as those of the fundamental resistive current, the third harmonic resistive current, and the dielectric loss factor of the leakage current signal of phase A of the zinc oxide arrester to be measured, and will not be elaborated here one by one.

[0156] According to the method for wireless synchronous measurement of the resistive current of a zinc oxide arrester according to an embodiment of the present invention, by collecting the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured and the grid phase A voltage signal, and then sending a first time synchronization instruction to the current acquisition units and voltage acquisition units of phases A, B, and C of the zinc oxide arrester to be measured through a convergence node to achieve the first time synchronization, and the current acquisition unit of phase A of the zinc oxide arrester to be measured sends a second time synchronization instruction to the current acquisition units and voltage acquisition units of phases B and C of the zinc oxide arrester to be measured according to the result of the first time synchronization to achieve the second time synchronization, and sampling is performed according to the result of the second time synchronization, and the sampling results and counter values are stored in their respective sampling data buffer areas. When the convergence node sends a synchronous acquisition instruction, each acquisition unit frames and transmits its respective sampling data to the convergence node. Finally, the convergence node wirelessly synchronously measures the resistive current of the zinc oxide arrester to be measured according to the sampled data frames, the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured, and the grid phase A voltage signal. Thus, the resistive current of the zinc oxide arrester can be wirelessly synchronously measured, and the aging of the zinc oxide arrester can be timely identified, thereby improving the service life of the zinc oxide arrester and the safety of the power system.

[0157] The traditional method for measuring zinc oxide arresters is wired and requires wiring, with complex installation. In the method of the present invention, wireless data transmission and synchronous acquisition are adopted between the convergence node, the current acquisition units of phases A, B, and C of the zinc oxide arrester, and the voltage acquisition unit, avoiding problems such as insulation damage or electromagnetic interference that may be caused by traditional wired connections, reducing the operation risk in a high-voltage environment, and being convenient for on-site installation and adaptable to harsh environments.

[0158] In addition, the present invention does not require a GPS or Beidou satellite time synchronization module, overcoming the problem that the PPS pulse may fail due to weather, faults, and other factors in the GPS or Beidou module. Only through the high-precision crystal oscillator and micro-power wireless communication inside the on-line monitoring device of the zinc oxide arrester, the synchronous sampling and measurement of each acquisition unit for the status monitoring of the zinc oxide arrester are realized, accurately capturing the phase and amplitude changes of the leakage current of the arrester, and saving the hardware cost.

[0159] Embodiment 3

[0160] To implement the wireless synchronous measurement method of the resistive current of the zinc oxide arrester in the above embodiment, the present invention also proposes a wireless synchronous measurement system for the resistive current of the zinc oxide arrester.

[0161] As Figure 7 shown, a wireless synchronous measurement system for the resistive current of a zinc oxide arrester includes: a signal acquisition module 100, a first time synchronization module 200, a second time synchronization module 300, a data sampling module 400, a synchronous acquisition module 500, and a synchronous measurement module 600. The signal acquisition module 100 is used to collect the leakage current signals of the A, B, and C phases of the zinc oxide arrester to be measured and the grid A-phase voltage signal according to the on-line monitoring device of the zinc oxide arrester. Among them, the on-line monitoring device of the zinc oxide arrester includes a convergence node, and the current acquisition units and voltage acquisition units of the A, B, and C phases of the zinc oxide arrester; the first time synchronization module 200 is used to send a first time synchronization instruction to the current acquisition units and voltage acquisition units of the A, B, and C phases of the zinc oxide arrester to be measured through the convergence node, so as to realize the first time synchronization of the convergence node to the current acquisition units and voltage acquisition units of the A, B, and C phases of the zinc oxide arrester to be measured;

[0162] The second time synchronization module 300 is used for the A-phase current acquisition unit of the zinc oxide arrester to be measured to send a second time synchronization instruction to the B-phase and C-phase current acquisition units and voltage acquisition units of the zinc oxide arrester to be measured according to the result of the first time synchronization, so as to realize the second time synchronization of the A-phase current acquisition unit of the zinc oxide arrester to be measured to the B-phase and C-phase current acquisition units and voltage acquisition units of the zinc oxide arrester to be measured. Specifically, it includes: presetting a fixed time interval through the hardware timers inside the current acquisition units and voltage acquisition units of the A, B, and C phases of the zinc oxide arrester to be measured as a counter, and the time interval is less than or equal to 10uS. Among them, the hardware inside the current acquisition units and voltage acquisition units of the A, B, and C phases of the zinc oxide arrester to be measured all uses a high-precision crystal oscillator with ±2ppm; after the current acquisition units and voltage acquisition units of the A, B, and C phases of the zinc oxide arrester to be measured are powered on for the first time, the counters built in the current acquisition units and voltage acquisition units of the A, B, and C phases of the zinc oxide arrester to be measured start counting from 0 respectively. Among them, due to the difference in the power-on time, the count values of the counters inside the current acquisition units and voltage acquisition units of the A, B, and C phases of the zinc oxide arrester to be measured are all different;

[0163] After the current acquisition unit of phase A of the zinc oxide arrester to be measured sends the second time synchronization instruction to the current acquisition units of phases B and C and the voltage acquisition unit of the zinc oxide arrester to be measured, the current acquisition units of phases B and C and the voltage acquisition unit of the zinc oxide arrester to be measured reset the count values of their own counters to zero; the data sampling module 400 is used for the current acquisition units of phases A, B, and C and the voltage acquisition unit of the zinc oxide arrester to be measured to perform A / D sampling every n counters according to the result of the second time synchronization, and store the sampling values and counter values in their respective sampling data buffers; the synchronous acquisition module 500 is used for the aggregation node to send a synchronous acquisition instruction to the current acquisition units of phases A, B, and C and the voltage acquisition unit of the zinc oxide arrester to be measured, and the current acquisition units of phases A, B, and C and the voltage acquisition unit of the zinc oxide arrester to be measured frame and transmit 127 sampling data before the sampling time point Q and including the sampling time point Q in their respective sampling data buffers to the aggregation node, wherein the synchronous acquisition instruction includes the time scale information of the sampling time point Q, that is, when the synchronous acquisition instruction is sent, the time scale of the counter is the sampling time point Q;

[0164] The synchronous measurement module 600 is used for the aggregation node to perform wireless synchronous measurement of the resistive current of the zinc oxide arrester to be measured according to the sampled data frame, the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured, and the grid phase A voltage signal.

[0165] In an embodiment of the present invention, the signal acquisition module 100 can clamp the current acquisition units of phases A, B, and C of the zinc oxide arrester to be measured with microampere current sensors on the connection lead between the zinc oxide arrester body and the lightning strike counter for collecting the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured. At the same time, the voltage acquisition unit of the zinc oxide arrester can also be connected to the phase A voltage line on the transmission line by using a voltage transformer for collecting the grid phase A voltage signal, and use the grid phase A voltage signal as the reference phase signal of the on-line monitoring device of the zinc oxide arrester.

[0166] In an embodiment of the present invention, after the aggregation node, the current acquisition units of phases A, B, and C and the voltage acquisition unit of the zinc oxide arrester to be measured are powered on and run, the first time synchronization module 200 can control the aggregation node to send the first time synchronization instruction to the current acquisition units of phases A, B, and C and the voltage acquisition unit of the zinc oxide arrester to be measured every 5 minutes to achieve time synchronization at the millisecond level. Among them, the aggregation node, the current acquisition units of phases A, B, and C and the voltage acquisition unit of the zinc oxide arrester to be measured all have micro-power wireless communication functions, and the aggregation node, the current acquisition units of phases A, B, and C and the voltage acquisition unit of the zinc oxide arrester to be measured can communicate with each other through micro-power wireless.

[0167] Among them, the first pair of timing modules 200 controls the first pair of timings of the aggregation node for the current acquisition unit and voltage acquisition unit of the zinc oxide lightning arrester to be measured for phases A, B, and C. Specifically, it may include: the aggregation node sends a first pair of timing instructions to the current acquisition unit of phase A of the zinc oxide lightning arrester to be measured, and the aggregation node records the time at which the first pair of timing instructions is sent as T1; after the current acquisition unit of phase A of the zinc oxide lightning arrester to be measured receives the first pair of timing instructions sent by the aggregation node, it performs message pair timing response on the first pair of timing instructions. Among them, the message of the pair timing response contains the time T2 when the first pair of timing instructions is received and the time T3 when the response message is sent; the aggregation node receives the pair timing response message of the current acquisition unit of phase A of the zinc oxide lightning arrester to be measured and records the reception time T4; the aggregation node calculates the time error ΔT between the aggregation node and the current acquisition unit of phase A of the zinc oxide lightning arrester to be measured due to the delay of the micro-power wireless communication. A1 , where the time error ΔT A1 The calculation formula of is:

[0168]

[0169] For the time error ΔT A1 Perform multiple calculations to obtain multiple time errors ΔT Am , where the aggregation node can perform 10 operations on the time error ΔT A1 , then m is a positive integer greater than or equal to 1 and less than or equal to 10; for multiple time errors ΔT Am Calculate the average value to obtain the average time error ΔT between the aggregation node and the current acquisition unit of phase A of the zinc oxide lightning arrester to be measured A , where the average time error ΔT A The calculation formula of is:

[0170] ΔT A = avg(ΔT Am );

[0171] Among them, avg is the average value taking function; the aggregation node combines the current time T5 and the average time error ΔT A to form an accurate pair timing message and sends an accurate pair timing instruction to the current acquisition unit of phase A of the zinc oxide lightning arrester to be measured. The time tag of the accurate pair timing instruction is (T 5+ ΔT A );

[0172] After the current acquisition unit of phase A of the zinc oxide lightning arrester to be measured receives the accurate pair timing instruction from the aggregation node, it modifies its own time; the aggregation node performs pair timing on the current acquisition units of phases B and C of the zinc oxide lightning arrester to be measured and the voltage acquisition unit in sequence according to the above steps.

[0173] Among them, the operation process of time synchronization for the current acquisition units and voltage acquisition units of phases B and C of the zinc oxide arrester to be measured is the same as that of the current acquisition unit of phase A of the zinc oxide arrester to be measured.

[0174] In an embodiment of the present invention, the second time synchronization module 300 can control the current acquisition unit of phase A of the zinc oxide arrester to be measured to perform time base micro-synchronization on the current acquisition units of phases B and C of the zinc oxide arrester to be measured every 5 seconds, and the time synchronization accuracy can reach the 10uS level. Among them, the second time synchronization of the current acquisition unit of phase A of the zinc oxide arrester to be measured to the current acquisition units of phases B and C of the zinc oxide arrester to be measured and the voltage acquisition unit specifically includes:

[0175] After the current acquisition units and voltage acquisition units of phases A, B, and C of the zinc oxide arrester to be measured are powered on for the first time, the counters built in the current acquisition units and voltage acquisition units of phases A, B, and C of the zinc oxide arrester to be measured start counting from 0 respectively; when the current acquisition unit of phase A of the zinc oxide arrester to be measured sends a second time synchronization instruction to the current acquisition units of phases B and C of the zinc oxide arrester to be measured and the voltage acquisition unit, the current acquisition units of phases B and C of the zinc oxide arrester to be measured and the voltage acquisition unit reset the count values of their own counters to zero.

[0176] Specifically, since the hardware inside each of the current acquisition units and voltage acquisition units of phases A, B, and C of the zinc oxide arrester to be measured uses a high-precision crystal oscillator of ±2ppm, a fixed time interval can be set through the timer integrated in the hardware CPU (Central Processing Unit), thereby implementing a counter Ticks, where the time interval is less than or equal to 10uS. For the convenience of subsequent description, the counters inside the current acquisition units and voltage acquisition units of phases A, B, and C of the zinc oxide arrester to be measured can be represented by TicksA, TicksB, TicksC, and TicksD respectively, and the count values of the counters can be represented by N A 、N B 、N C and N D respectively.

[0177] After the current acquisition units and voltage acquisition units of phases A, B, and C of the zinc oxide arrester to be measured are powered on for the first time, TicksA, TicksB, TicksC, and TicksD start counting from 0 respectively. Due to the difference in the power-on time, there will be a situation of counting asynchrony for TicksA, TicksB, TicksC, and TicksD, and the count values of TicksA, TicksB, TicksC, and TicksD may all be different. Among them, PO represents the power-on time of the current acquisition units and voltage acquisition units of phases A, B, and C of the zinc oxide arrester to be measured.

[0178] After the current acquisition unit of phase A of the zinc oxide arrester to be measured sends the second pairing instruction to the current acquisition units of phases B and C and the voltage acquisition unit of the zinc oxide arrester to be measured, all acquisition units that receive the second pairing instruction reset the count value of their own counter to zero, that is, Ticks starts counting from 0. Among them, N’ A 、N’ B 、N’ C 、N’ D can represent the count values of the counters inside the current acquisition units of phases A, B, and C and the voltage acquisition unit of the zinc oxide arrester to be measured before receiving the second pairing instruction in the next synchronization period.

[0179] In a specific embodiment of the present invention, after the first pairing and the second pairing are completed, the data acquisition module 400 can control the current acquisition units of phases A, B, and C and the voltage acquisition unit of the zinc oxide arrester to be measured to start A / D sampling every 15 Ticks. That is to say, if the period of the counter is 10uS, then the current acquisition units of phases A, B, and C and the voltage acquisition unit of the zinc oxide arrester to be measured can start A / D sampling every 150uS, sample 1 point at a time, and store the sampling value and the counter value.

[0180] In a specific embodiment of the present invention, as Figure 5 shown, when the aggregation node needs to send a synchronous acquisition instruction to the current acquisition units of phases A, B, and C and the voltage acquisition unit of the zinc oxide arrester to be measured, the synchronous acquisition module 500 can control the aggregation node to send the synchronous acquisition instruction through micro-power wireless communication. The synchronous acquisition instruction can include the time scale information of the sampling time point Q, that is, Ticks = Q. After receiving the synchronous acquisition instruction from the aggregation node, the current acquisition units of phases A, B, and C and the voltage acquisition unit of the zinc oxide arrester to be measured frame and transmit the sampling data with the time scale of Q and 127 sampling data groups before point Q in their respective sampling data buffers to the aggregation node.

[0181] In an embodiment of the present invention, the synchronous measurement module 600 can specifically be used to: obtain the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured and the grid phase A voltage signal according to the discrete Fourier transform; calculate the amplitude, phase angle, and effective value of the k-th harmonic of the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured, and the phase angle of the grid phase A voltage signal according to the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured and the grid phase A voltage signal, wherein the grid phase A voltage signal is used as the reference phase signal of the on-line monitoring device of the zinc oxide arrester; calculate the phase angle difference between the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured and the reference phase signal according to the phase angles of the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured and the grid phase A voltage signal; calculate the fundamental wave resistive current, third harmonic resistive current, and dielectric loss factor of the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured according to the phase angle difference between the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured and the reference phase signal.

[0182] Specifically, in an embodiment of the present invention, taking the leakage current signal of phase A of the zinc oxide arrester to be measured as an example, first, the leakage current signal of phase A of the zinc oxide arrester to be measured can be collected by the current acquisition unit of phase A of the zinc oxide arrester to be measured through A / D sampling. Among them, the waveform sequence of the leakage current signal of phase A of the zinc oxide arrester to be measured can be expressed as a periodic signal as follows:

[0183]

[0184] where, I A (t) is the leakage current signal of phase A of the zinc oxide arrester to be measured, I A0 is the DC component of the leakage current signal of phase A of the zinc oxide arrester to be measured, I Ak is the amplitude of the k-th harmonic of the leakage current signal of phase A of the zinc oxide arrester to be measured, k is a positive integer, ω is the angular frequency, and φ Ak is the phase angle of the k-th harmonic of the leakage current signal of phase A of the zinc oxide arrester to be measured.

[0185] Among them, the waveform sequences of the leakage current signals of phases B and C of the zinc oxide arrester to be measured and the grid phase A voltage signal are the same as the waveform sequence of the leakage current signal of phase A of the zinc oxide arrester to be measured expressed as a periodic signal, and will not be elaborated here one by one.

[0186] Furthermore, according to the sampling theorem and discrete Fourier transform, the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signals of the ZnO lightning arresters A, B, and C to be measured and the grid A-phase voltage signal can be obtained. In an embodiment of the present invention, taking the leakage current signal of the ZnO lightning arrester A to be measured as an example, the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signal of the ZnO lightning arrester A to be measured can be respectively expressed as:

[0187]

[0188] where a kn is the real part of the Fourier coefficient of the fundamental wave and harmonic components of the leakage current signal of the ZnO lightning arrester A to be measured, b kn is the imaginary part of the Fourier coefficient of the fundamental wave and harmonic components of the leakage current signal of the ZnO lightning arrester A to be measured, T is the sampling period, I A (n) is the nth A / D sampling value of the leakage current signal of the ZnO lightning arrester A to be measured, n = 1, 2,..., 127, N = 128, and k is a positive integer.

[0189] Among them, the expressions of the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signals of the ZnO lightning arresters B and C to be measured and the grid A-phase voltage signal are the same as those of the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signal of the ZnO lightning arrester A to be measured, and will not be elaborated here one by one.

[0190] Furthermore, according to the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signals of the ZnO lightning arresters A, B, and C to be measured and the grid A-phase voltage signal, calculate the amplitude, phase angle, and effective value of the kth harmonic of the leakage current signals of the ZnO lightning arresters A, B, and C to be measured, and the phase angle of the grid A-phase voltage signal.

[0191] In an embodiment of the present invention, taking the leakage current signal of the ZnO lightning arrester A to be measured as an example, the amplitude, phase angle, and effective value of the kth harmonic of the leakage current signal of the ZnO lightning arrester A to be measured can be respectively expressed as:

[0192]

[0193] where I Ak is the amplitude of the kth harmonic of the leakage current signal of the ZnO lightning arrester A to be measured, φ Ak is the phase angle of the kth harmonic of the leakage current signal of the ZnO lightning arrester A to be measured, is the effective value of the kth harmonic of the leakage current signal of the ZnO lightning arrester A to be measured; the phase angle of the grid A-phase voltage signal is expressed as:

[0194] φUAk = arctg(b UAkn a UAkn );

[0195] Wherein, b UAkn is the imaginary part of the Fourier coefficient of the fundamental wave and harmonic components of the grid A-phase voltage signal, and a UAkn is the real part of the Fourier coefficient of the fundamental wave and harmonic components of the grid A-phase voltage signal. And in this embodiment, the grid A-phase voltage signal can be used as the reference phase.

[0196] Wherein, the expressions of the amplitude, phase angle and effective value of the k-th harmonic of the leakage current signals of phases B and C of the zinc oxide arrester to be measured are the same as those of the leakage current signal of phase A of the zinc oxide arrester to be measured, and will not be elaborated here one by one.

[0197] It should be noted that since the grid A-phase voltage signal is used as the reference phase, when performing discrete Fourier transform, only the phase angle of the grid A-phase voltage signal needs to be calculated, and the amplitude and effective value of the grid A-phase voltage signal do not need to be calculated.

[0198] Furthermore, in an embodiment of the present invention, taking the leakage current signal of phase A of the zinc oxide arrester to be measured as an example, the phase angle of the k-th harmonic of the leakage current signal of phase A of the zinc oxide arrester to be measured can be subtracted from the phase angle of the k-th harmonic of the grid A-phase voltage signal, and the phase angle difference between the k-th harmonic of the leakage current signal of phase A of the zinc oxide arrester to be measured and the k-th harmonic of the grid A-phase voltage signal can be obtained, that is, φ IAk = φ Ak - φ UAk At this time, k = 1 can be substituted to obtain the phase angle difference between the leakage current signal of phase A of the zinc oxide arrester to be measured and the grid A-phase voltage signal, that is, φ IA1 = φ A1 - φ UA1 .

[0199] Finally, the fundamental resistive current, third harmonic resistive current and dielectric loss factor of the leakage current signals of phases A, B and C of the zinc oxide arrester to be measured can be calculated according to the phase angle differences of the leakage current signals of phases A, B and C of the zinc oxide arrester to be measured and the reference phase signal.

[0200] In an embodiment of the present invention, taking the leakage current signal of phase A of the zinc oxide arrester to be measured as an example, the fundamental resistive current, third harmonic resistive current and dielectric loss factor of the leakage current signal of phase A of the zinc oxide arrester to be measured can be respectively expressed as:

[0201]

[0202] Wherein, IA1r is the fundamental resistive current of the leakage current signal of the zinc oxide arrester's phase A to be measured, I A3r is the third harmonic resistive current of the leakage current signal of the zinc oxide arrester's phase A to be measured, tgσ A is the dielectric loss factor of the leakage current signal of the zinc oxide arrester's phase A to be measured.

[0203] Among them, the expressions of the fundamental resistive current, third harmonic resistive current, and dielectric loss factor of the leakage current signals of phases B and C of the zinc oxide arrester to be measured are the same as those of the fundamental resistive current, third harmonic resistive current, and dielectric loss factor of the leakage current signal of phase A of the zinc oxide arrester to be measured, and will not be elaborated here one by one.

[0204] In summary, the present invention collects the leakage current signals of phases A, B, and C of the zinc oxide arrester to be measured and the grid phase A voltage signal through the signal acquisition module, then realizes the first time synchronization by sending the first time synchronization instruction through the first time synchronization module, realizes the second time synchronization by sending the second time synchronization instruction through the second time synchronization module, and samples according to the result of the second time synchronization through the data acquisition module, stores the sampling result and the counter value in their respective sampling data buffer areas. When the aggregation node sends a synchronous acquisition instruction, the synchronous acquisition module frames and transmits the sampling data to the aggregation node, and finally wirelessly synchronously measures the resistive current of the zinc oxide arrester to be measured through the synchronous measurement module. Thus, it can wirelessly synchronously measure the resistive current of the zinc oxide arrester, can timely identify the aging of the zinc oxide arrester, and thereby improve the service life of the zinc oxide arrester and the safety of the power system.

[0205] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. The meaning of "a plurality" is two or more, unless otherwise clearly and specifically defined.

[0206] In the present invention, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected to", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0207] In the present invention, unless otherwise clearly defined or limited, a first feature being "on" or "under" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "over" and "on top of" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the horizontal height of the first feature is higher than that of the second feature. A first feature being "under", "below" and "beneath" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the horizontal height of the first feature is less than that of the second feature.

[0208] In the description of this specification, the description of reference terms such as "an embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0209] Any process or method description, whether in a flowchart or described otherwise herein, can be understood to represent a module, segment, or portion of code including one or more executable instructions for implementing a specific logical function or process. The scope of the preferred embodiments of the present invention includes additional implementations, where the functions may be executed in a manner not shown or discussed, including in a substantially simultaneous manner or in a reverse order according to the functions involved, which should be understood by those skilled in the art to which the embodiments of the present invention pertain.

[0210] The logic and / or steps represented in the flowchart or otherwise described herein can, for example, be considered as a definitional sequence list of executable instructions for implementing logical functions, and can be embodied specifically in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium include the following: an electrical connection part having one or more wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable medium on which the program can be printed, as the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpretation, or otherwise processing as appropriate, and then storing it in a computer memory.

[0211] It should be understood that various parts of the present invention can be implemented by hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0212] Those of ordinary skill in the art of this technology can understand that all or part of the steps carried by the method of the above embodiments can be completed by instructing relevant hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

[0213] In addition, each functional unit in various embodiments of the present invention may be integrated into a processing module, may exist separately physically for each unit, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. When the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0214] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A wireless synchronous measurement method for resistive current of zinc oxide arrester, characterized in that, The method includes the following steps: An on-line monitoring device of a zinc oxide arrester is used to collect leakage current signals corresponding to the zinc oxide arresters on phases A, B, and C of the line and the A-phase voltage signal of the power grid. Among them, the on-line monitoring device of the zinc oxide arrester is installed on the power grid and includes a convergence node, a voltage acquisition unit, and current acquisition units for phases A, B, and C. The current acquisition units for phases A, B, and C are respectively connected to the zinc oxide arresters on phases A, B, and C of the line, and are respectively used to collect the leakage current signals to be measured corresponding to the zinc oxide arresters on phases A, B, and C of the line; the voltage acquisition unit is used to collect the voltage signal on the A-phase line of the power grid, and the convergence node is wirelessly connected to the voltage acquisition unit and the current acquisition units for phases A, B, and C, and sends relevant instructions; The convergence node sends a first time synchronization instruction to the current acquisition units for phases A, B, and C and the voltage acquisition unit, and completes the first time synchronization of the current acquisition units for phases A, B, and C and the voltage acquisition unit; The current acquisition unit for phase A sends a second time synchronization instruction to the current acquisition units for phases B and C and the voltage acquisition unit according to the time after the first time synchronization. The current acquisition units for phases B and C and the voltage acquisition unit reset the count value of their own counters to zero and start counting from zero; After the first time synchronization and the second time synchronization are completed, the convergence node stores the sampling values of the leakage current signals to be measured for phases A, B, and C and the voltage signal of the A-phase of the power grid each time and the value of the current counter in their respective sampling data buffers; The convergence node performs wireless synchronous measurement of the resistive currents corresponding to the leakage current signals to be measured for phases A, B, and C and the voltage signal of the A-phase of the power grid according to the sampling data group frames obtained from the sampling values and the values of the corresponding counters.

2. The method for wireless synchronous measurement of resistive current of zinc oxide lightning arrester according to claim 1, characterized in that The completion of the first time synchronization of the current acquisition units for phases A, B, and C and the voltage acquisition unit specifically includes: The convergence node sends a first time synchronization instruction to the current acquisition unit for phase A, and records the time T1 at the moment when the first time synchronization instruction is sent; After receiving the first time synchronization instruction sent by the convergence node, the current acquisition unit for phase A performs message time synchronization response to the first time synchronization instruction. Among them, the time T2 when the first time synchronization instruction is received and the time T3 at the moment when the response message is sent are included in the time synchronization response message; The convergence node receives the time synchronization response message of the current acquisition unit for phase A and records the reception time T4, and further obtains the time error during information reception between the convergence node and the current acquisition unit for phase A caused by the delay of the micro-power wireless communication; Perform the operation of receiving and transmitting the first pair of timing commands multiple times to obtain T1, T2, T3, and T4 at different times, calculate the time error multiple times to obtain multiple time error values, and calculate the average value of the multiple time error values to obtain the average time error ΔT A ; The convergence node forms an accurate time synchronization message with the current time T5 and the average time error, and sends an accurate time synchronization instruction to the current acquisition unit for phase A; The convergence node sequentially performs the first time synchronization on the current acquisition units for phases B and C and the voltage acquisition unit.

3. The method for wireless synchronous measurement of resistive current of zinc oxide arrester according to claim 2, characterized in that, The operation of receiving and transmitting the first pair of time commands multiple times is performed to obtain T1, T2, T3, and T4 at different times, and the time error is calculated multiple times to obtain multiple time error values. The average value of the multiple time error values is obtained to get the average time error ΔT A , which is expressed as: ΔT A = avg(ΔT Am ); ΔT Am =(T 2m - T 1m ) - (T 4m - T 3m ) / 2; Among them, ΔT Am is the time error value corresponding to the instruction operation during the m-th transceiver of the first pair, T 1m is the time of the sending moment of the first pair instruction in the instruction operation during the m-th transceiver of the first pair, T 2m is the time when the A-phase current acquisition unit receives the first pair instruction in the instruction operation during the m-th transceiver of the first pair, T 3m is the time of the sending moment of the response message of the A-phase current acquisition unit in the instruction operation during the m-th transceiver of the first pair, T 4m is the time when the aggregation node receives the time synchronization response message of the A-phase current acquisition unit in the instruction operation during the m-th transceiver of the first pair.

4. The method for wireless synchronous measurement of resistive current of zinc oxide lightning arrester according to claim 3, characterized in that, The current acquisition unit for phase A sending a second time synchronization instruction to the current acquisition units for phases B and C and the voltage acquisition unit according to the time after the first time synchronization further includes: It represents the count values of the counters inside the phase-A, phase-B, and phase-C current acquisition units and the voltage acquisition unit before receiving the synchronous acquisition instruction in the next synchronous cycle.

5. The method for wireless synchronous measurement of resistive current of zinc oxide lightning arrester according to claim 4, characterized in that The aggregation node stores the sampling values of the leakage current signals to be measured for phase-A, phase-B, and phase-C and the voltage signal of phase-A of the power grid and the current value of the current counter in their respective sampling data buffers each time. The set sampling frequency is: The phase-A, phase-B, and phase-C current acquisition units and the voltage acquisition unit start an A / D sampling every M timers, that is, start an A / D sampling every M*N, where N is the period of the counter, and store the signal sampling values and the counter values.

6. The method for wireless synchronous measurement of resistive current of zinc oxide lightning arrester according to any one of claims 1-5, characterized in that After completing the first pairing and the second pairing, the aggregation node stores the sampling values of the leakage current signals to be measured for phase-A, phase-B, and phase-C and the voltage signal of phase-A of the power grid and the current value of the current counter in their respective sampling data buffers each time. What follows also includes: The aggregation node sends a synchronous acquisition instruction to the phase-A, phase-B, and phase-C current acquisition units and the voltage acquisition unit. The phase-A, phase-B, and phase-C current acquisition units and the voltage acquisition unit frame and transmit the sampling data in their respective sampling data buffers that contain the sampling time point Q and the sampling data group before point Q to the aggregation node. Among them, the synchronous acquisition instruction contains the time scale information of the sampling time point Q, that is, when sending the synchronous acquisition instruction, the time scale of the counter is the sampling time point Q.

7. The method for wireless synchronous measurement of resistive current of zinc oxide lightning arrester according to claim 6, characterized in that, The aggregation node performs wireless synchronous measurement on the resistive currents corresponding to the leakage current signals to be measured for phase-A, phase-B, and phase-C and the voltage signal of phase-A of the power grid according to the sampling data frames obtained from the sampling values and the corresponding counter values. Specifically, it includes: Obtaining the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signals to be measured for phase-A, phase-B, and phase-C and the voltage signal of phase-A of the power grid from the sampling data frames obtained from the sampling values; Calculating the amplitude, phase angle, and effective value of the kth harmonic corresponding to the measurement, and the phase angle of the voltage signal of phase-A of the power grid according to the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signals to be measured for phase-A, phase-B, and phase-C and the voltage signal of phase-A of the power grid. Among them, the voltage signal of phase-A of the power grid is used as the reference phase signal of the on-line monitoring device of the zinc oxide arrester; Obtaining the phase angle differences between the leakage current signals to be measured for phase-A, phase-B, and phase-C and the reference phase signal according to the phase angles of the leakage current signals to be measured for phase-A, phase-B, and phase-C and the phase angle of the voltage signal of phase-A of the power grid; Obtaining the fundamental wave resistive current, third harmonic resistive current, and dielectric loss factor of the leakage current signals for phase-A, phase-B, and phase-C according to the phase angle differences; 8. The method for wireless synchronous measurement of resistive current of zinc oxide lightning arrester according to claim 7, characterized in that The obtaining the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signals to be measured for phase-A, phase-B, and phase-C and the voltage signal of phase-A of the power grid from the sampling data frames obtained from the sampling values includes: The Fourier coefficients of the fundamental wave component and harmonic components of the phase-A leakage current signal are respectively expressed as: where a kn is the real part of the Fourier coefficient of the fundamental wave and harmonic components of the leakage current signal of phase A of the zinc oxide arrester to be measured, b kn is the imaginary part of the Fourier coefficient of the fundamental wave and harmonic components of the leakage current signal of phase A of the zinc oxide arrester to be measured, T is the sampling period, I A (n) is the nth A / D sampling value of the leakage current signal of phase A, n = 1, 2, …, 127, N = 128, and k is a positive integer.

9. The method for wireless synchronous measurement of resistive current of zinc oxide arrester according to claim 8, characterized in that, Calculating the amplitude, phase angle, and effective value of the k-th harmonic corresponding to the measurement, as well as the phase angle of the grid A-phase voltage signal, based on the Fourier coefficients of the fundamental wave components and harmonic components of the leakage current signals to be measured for phases A, B, and C and the grid A-phase voltage signal, includes: The amplitude, phase angle, and effective value of the k-th harmonic of the phase A leakage current signal are respectively expressed as: Among them, I Ak is the amplitude of the k-th harmonic of the A-phase leakage current signal, and φ Ak is the phase angle of the k-th harmonic of the A-phase leakage current signal, is the effective value of the k-th harmonic of the A-phase leakage current signal; The phase angle of the grid A-phase voltage signal is expressed as: φ UAk = arctan(b UAkn / a UAkn ); Among them, b UAkn is the imaginary part of the Fourier coefficients of the fundamental and harmonic components of the grid A-phase voltage signal, and a UAkn is the real part of the Fourier coefficients of the fundamental and harmonic components of the grid A-phase voltage signal.

10. The method for wireless synchronous measurement of resistive current of zinc oxide lightning arrester according to claim 9, characterized in that, Obtaining the fundamental resistive current, third-harmonic resistive current, and dielectric loss factor of the leakage current signals for phases A, B, and C based on the phase angle difference, includes: The fundamental resistive current, third-harmonic resistive current, and dielectric loss factor of the phase A leakage current signal are respectively expressed as: Among them, I A1r is the fundamental resistive current of the leakage current signal of phase A, I A3r is the third harmonic resistive current of the leakage current signal of phase A, tgσ A is the dielectric loss factor of the leakage current signal of phase A, φ IA1 is the phase angle difference between the leakage current signal of phase A and the grid phase A voltage signal, φ IA1 = φ A1 - φ UA1 , φ UA1 that is, φ UAk is the phase angle corresponding to k = 1 in φ A1 is φ Ak is the phase angle corresponding to k = 1 in φ 。 11. A wireless synchronous measurement system for resistive current of zinc oxide lightning arrester, characterized in that, This system includes: A signal acquisition module, which uses an on-line monitoring device of a zinc oxide arrester to acquire the leakage current signals corresponding to the zinc oxide arresters on phases A, B, and C of the line and the grid A-phase voltage signal. Among them, the on-line monitoring device of the zinc oxide arrester is installed on the grid and includes a convergence node, a voltage acquisition unit, and current acquisition units for phases A, B, and C. The current acquisition units for phases A, B, and C are respectively connected to the zinc oxide arresters on phases A, B, and C of the line and are respectively used to acquire the leakage current signals to be measured corresponding to the zinc oxide arresters on phases A, B, and C of the line; the voltage acquisition unit is used to acquire the voltage signal on the grid A-phase line, and the convergence node is wirelessly communicatively connected to the voltage acquisition unit and the current acquisition units for phases A, B, and C and sends relevant instructions; A first time synchronization module, which uses the convergence node to send a first time synchronization instruction to the current acquisition units for phases A, B, and C and the voltage acquisition unit and completes the first time synchronization of the current acquisition units for phases A, B, and C and the voltage acquisition unit; A second time synchronization module, which uses the phase A current acquisition unit to send a second time synchronization instruction to the phase B and C current acquisition units and the voltage acquisition unit according to the time after the first time synchronization. The phase B and C current acquisition units and the voltage acquisition unit reset the count value of their own counters to zero and start counting from zero; A data sampling module, which is used to, after the first time synchronization and the second time synchronization are completed, the convergence node stores the sampling values of the leakage current signals to be measured for phases A, B, and C and the grid A-phase voltage signal each time and the current value of the current counter in their respective sampling data buffers; A synchronous measurement module, which uses the convergence node to perform wireless synchronous measurement of the resistive currents corresponding to the leakage current signals to be measured for phases A, B, and C and the grid A-phase voltage signal according to the sampling data group frames obtained from the sampling values and the corresponding counter values.

12. The resistive current wireless synchronous measurement system for zinc oxide lightning arrester according to claim 11, characterized in that, The system further includes a synchronous acquisition module, which is arranged between the data sampling module and the synchronous measurement module and is used for: using the aggregation node to send synchronous acquisition instructions to the A-phase, B-phase, and C-phase current acquisition units and voltage acquisition units, and the A-phase, B-phase, and C-phase current acquisition units and voltage acquisition units frame and transmit the sampling data in their respective sampling data buffers that include the sampling time point Q and the sampling data before the point Q to the aggregation node, wherein the synchronous acquisition instruction includes the time scale information of the sampling time point Q, that is, when the synchronous acquisition instruction is sent, the time scale of the counter is the sampling time point Q.

13. A computer-readable storage medium stores a computer program, characterized in that, When the computer program is executed by a processor, it implements the method for wireless synchronous measurement of resistive current of zinc oxide arresters as described in any one of claims 1 to 10.

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