Smart power grid single-ended grounding system evaluation method and device based on multi-frequency injection

Abstract

The invention discloses an intelligent power grid single-ended grounding system evaluation method and device based on multi-frequency injection, and relates to the technical field of intelligent power grids. Through accurate state diagnosis, dynamic monitoring and strong anti-interference capability, live detection of the high-voltage cable single-ended grounding system is realized. Fault power failure can be reduced, maintenance cost and electric energy loss are reduced, power supply reliability is improved, and safety and economical efficiency of a power grid are remarkably enhanced.

Description

Technical Field

[0001] This invention discloses an evaluation method and apparatus for a single-ended grounding system of a smart grid based on multi-frequency injection, which relates to the field of smart grid technology. Background Technology

[0002] High-voltage cables are a crucial component of power systems, and their safe operation is essential for the reliability of power supply. In high-voltage cable systems, single-end grounding is a common grounding method, typically used for short-distance cable lines or connections between cables and overhead lines. In this grounding method, the cable's metallic sheath or shielding is grounded at only one end, while the other end remains insulated to prevent circulating currents and reduce energy loss.

[0003] However, the connection status of a single-ended grounding system can be affected by a variety of factors. For example, after long-term operation, the grounding terminals may loosen due to oxidation, corrosion, or mechanical vibration, leading to increased contact resistance; aging or damage to the cable insulation may cause partial discharge, thus affecting the performance of the grounding system; in addition, external damage, poor construction quality, and other factors may also lead to poor grounding system connections. If these problems are not detected and addressed in a timely manner, they may cause a series of serious consequences, such as overheating of the grounding system, insulation breakdown, or even power outages, threatening the safe and stable operation of the power system.

[0004] Currently, the main method for detecting the connection status of single-end grounding systems of high-voltage cables relies on periodic power outages. This method requires interrupting the power supply, which not only affects users' normal electricity use but also causes significant economic losses. Moreover, power outage detection only reflects the connection status at the moment of detection and cannot monitor changes in the cable's status during operation. In addition, while some live-line detection methods can be performed while the cable is running, they suffer from low detection accuracy and poor anti-interference capabilities, making it difficult to accurately determine the true connection status of the grounding system. Summary of the Invention

[0005] This invention addresses the problems of existing technologies by providing a method and apparatus for evaluating single-ended grounding systems in smart grids based on multi-frequency injection. The technical solution adopted is as follows: Firstly, a method for evaluating a single-ended grounding system in a smart grid based on multi-frequency injection includes: S1, based on the measurement sensor module, signals are injected between phases of the single-ended protective grounding system through three-way power test clamps; S2, based on the excitation signal, controls the excitation signal and switches the LC module through adjustable inductors and adjustable capacitors to obtain the measurement signal; S3, by switching the LC module, the equivalent impedance is obtained using the adjustable inductor and adjustable capacitor through the admittance method; S4, the grounding loop resistance is evaluated by measuring the single-ended protective grounding loop resistance R; In some implementations, S1, the current sensors measure the magnitude of the injected current, and the power test clamp injects and measures the voltage signal for phases AB, AC, and BC respectively, according to the signal injection sequence.

[0006] In some implementations, in S3, the equivalent impedance is obtained through the admittance method, including: S41, calculate the equivalent impedance ZLC of the parallel LC section, using the following formula: Anti-X L = wL Capacitive

[0007] Sum of admittances: Inductor admittance:

[0008] Capacitor admittance:

[0009] Total Admission:

[0010] S42, connected in series with a resistor, yields the total impedance Ztotal, as shown in the following formula: Equivalent impedance

[0011]

[0012] Total impedance (R and (in series) Resistance R and After being connected in series, the total impedance is a complex summation:

[0013] In some implementations, in S1, the power test clamp injects and measures voltage signals for phases AB, AC, and BC respectively, according to the signal injection sequence, including: S11, connect the AB phase grounding loop, the controller controls the excitation module to generate an excitation signal with frequency f1 and simultaneously adjusts the LC module, according to the formula Calculate the value of LC, and then calculate the impedance.

[0014] ; S12, repeat S11, inject at a known frequency. , ,…, Measure the corresponding impedance , ,…, .

[0015] S13, Construct a system of equations: Substitute the impedance corresponding to each frequency into the formula to obtain n equations, where L and C are unknowns, and R is the quantity to be determined: For each frequency Substitute into the formula:

[0016] We obtain a system of n equations:

[0017]

[0018] S14, fit the value of R using the least squares method, or simplify the calculation by selecting the high-frequency / low-frequency limiting case: High-frequency limit (f→∞): The inductive reactance of the inductor L is much greater than that of the resistor, and the capacitive reactance of the capacitor C approaches 0. At this time, Z≈R.

[0019] Low-frequency limit (f→0): The inductive reactance of inductor L approaches 0, and the capacitive reactance of capacitor C approaches infinity. At this time, Z≈R.

[0020] Secondly, embodiments of the present invention provide an evaluation device for a single-ended grounding system of a smart grid based on multi-frequency injection, comprising: The signal injection unit is used to inject signals between phases of the single-ended protective grounding system according to the excitation sensor module through three power test clamps; The signal measurement unit is used to control the excitation signal and switch the LC module according to the excitation signal through adjustable inductors and adjustable capacitors to obtain the measurement signal; Impedance analysis unit is used to obtain the equivalent impedance by means of the adjustable inductor and adjustable capacitor through the admittance method by switching the LC module; The grounding assessment unit is used to assess the resistance of a grounding loop by measuring the resistance R of a single-ended protective grounding loop.

[0021] In some implementations, in the signal injection unit, the current sensor measures the magnitude of the injected current, and the power test clamp injects and measures the voltage signal for phases AB, AC, and BC respectively according to the signal injection sequence.

[0022] In some implementations, the equivalent impedance is obtained in the impedance analysis unit by means of the admittance method, including: The equivalent impedance sub-unit is used to calculate the equivalent impedance ZLC of the parallel LC section, as shown in the following formula: Anti-X L = wL Capacitive

[0023] Sum of admittances: Inductor admittance:

[0024] Capacitor admittance:

[0025] Total Admission:

[0026] The total impedance sub-unit is used in series with a resistor to obtain the total impedance Ztotal, as shown in the following formula: Equivalent impedance

[0027]

[0028] Total impedance (R and (in series) Resistance R and After being connected in series, the total impedance is a complex summation:

[0029] In some implementations, the signal injection unit includes: The impedance analysis subunit is used to connect the AB phase grounding loop. The controller controls the excitation module to generate an excitation signal with frequency f1 while adjusting the LC module, according to the formula... Calculate the value of LC, and then calculate the impedance. :

[0030] The analytical processing subunit is used to repeat the impedance analysis subunit operation and inject a known frequency. , ,…, Measure the corresponding impedance , ,…, .

[0031] Equation building sub-units are used to construct a system of equations: Substituting the impedance corresponding to each frequency into the formula yields n equations, where L and C are unknowns, and R is the unknown quantity: For each frequency Substitute into the formula:

[0032] We obtain a system of n equations:

[0033]

[0034] Impedance handling subunits are used to fit the value of R using the least squares method, or to simplify calculations by selecting high-frequency / low-frequency limiting cases. High-frequency limit (f→∞): The inductive reactance of the inductor L is much greater than that of the resistor, and the capacitive reactance of the capacitor C approaches 0. At this time, Z≈R.

[0035] Low-frequency limit (f→0): The inductive reactance of inductor L approaches 0, and the capacitive reactance of capacitor C approaches infinity. At this time, Z≈R.

[0036] In some implementations, Thirdly, embodiments of the present invention provide an electronic device, including a memory and a processor, wherein the memory is used to store one or more computer instructions, wherein when the one or more computer instructions are executed by the processor, they implement the method described in the first aspect above.

[0037] Fourthly, embodiments of the present invention provide a computer storage medium, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, it implements the method described in the first aspect.

[0038] One or more embodiments of the present invention can bring at least the following beneficial effects: This invention enables live-line detection of single-end grounded high-voltage cable systems through precise condition diagnosis, dynamic monitoring, and strong anti-interference capabilities. It reduces power outages, lowers maintenance costs and energy losses, improves power supply reliability, and significantly enhances grid security and economy. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a block diagram of a single-ended grounding system structure, which is part of an evaluation method for a single-ended grounding system of a smart grid based on multi-frequency injection, provided in an embodiment of the present invention. Figure 2 This is a test wiring diagram for a single-ended grounding system provided in an embodiment of the present invention. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0042] Example 1: Figure 1 A block diagram of a single-ended grounding system structure is shown, illustrating an evaluation method for a smart grid single-ended grounding system based on multi-frequency injection. Figure 1 As shown in this embodiment, the evaluation method for a single-ended grounding system of a smart grid based on multi-frequency injection includes: S1, based on the measurement sensor module, signals are injected between phases of the single-ended protective grounding system through three-way power test clamps; S2, based on the excitation signal, controls the excitation signal and switches the LC module through adjustable inductors and adjustable capacitors to obtain the measurement signal; S3, by switching the LC module, the equivalent impedance is obtained using the adjustable inductor and adjustable capacitor through the admittance method; S4, the grounding loop resistance is evaluated by measuring the single-ended protective grounding loop resistance R; The following evaluation criteria shall be followed: Table 1

[0043] Furthermore, in S1, the current sensors measure the magnitude of the injected current, and the power test clamp injects and measures the voltage signal for phases AB, AC, and BC respectively, according to the signal injection sequence.

[0044] Furthermore, in S3, the equivalent impedance is obtained through the admittance method, including: S41, calculate the equivalent impedance ZLC of the parallel LC section, using the following formula: Anti-X L = wL Capacitive

[0045] Sum of admittances: Inductor admittance:

[0046] Capacitor admittance:

[0047] Total Admission:

[0048] S42, connected in series with a resistor, yields the total impedance Ztotal, as shown in the following formula: Equivalent impedance

[0049]

[0050] Total impedance (R and (in series) Resistance R and After being connected in series, the total impedance is a complex summation:

[0051] Furthermore, in S1, the power test clamp injects and measures voltage signals for phases AB, AC, and BC respectively, according to the signal injection sequence, including: S11, connect the AB phase grounding loop, the controller controls the excitation module to generate an excitation signal with frequency f1 and simultaneously adjusts the LC module, according to the formula Calculate the value of LC, and then calculate the impedance.

[0052]

[0053] S12, repeat S11, inject at a known frequency. , ,…, Measure the corresponding impedance , ,…, .

[0054] S13, Construct a system of equations: Substitute the impedance corresponding to each frequency into the formula to obtain n equations, where L and C are unknowns, and R is the quantity to be determined: For each frequency Substitute into the formula:

[0055] We obtain a system of n equations:

[0056]

[0057] S14, fit the value of R using the least squares method, or simplify the calculation by selecting the high-frequency / low-frequency limiting case: High-frequency limit (f→∞): The inductive reactance of the inductor L is much greater than that of the resistor, and the capacitive reactance of the capacitor C approaches 0. At this time, Z≈R.

[0058] Low-frequency limit (f→0): The inductive reactance of inductor L approaches 0, and the capacitive reactance of capacitor C approaches infinity. At this time, Z≈R.

[0059] Example 2: Secondly, embodiments of the present invention provide an evaluation device for a single-ended grounding system of a smart grid based on multi-frequency injection, comprising: The signal injection unit is used to inject signals between phases of the single-ended protective grounding system according to the excitation sensor module through three power test clamps; The signal measurement unit is used to control the excitation signal and switch the LC module according to the excitation signal through adjustable inductors and adjustable capacitors to obtain the measurement signal; Impedance analysis unit is used to obtain the equivalent impedance by means of the adjustable inductor and adjustable capacitor through the admittance method by switching the LC module; The grounding assessment unit is used to assess the resistance of a grounding loop by measuring the resistance R of a single-ended protective grounding loop.

[0060] Furthermore, in the signal injection unit, the current sensors measure the magnitude of the injected current, and the power test clamp injects and measures the voltage signal for phases AB, AC, and BC respectively, according to the signal injection sequence.

[0061] Furthermore, in the impedance analysis unit, the equivalent impedance is obtained through the admittance method, including: The equivalent impedance sub-unit is used to calculate the equivalent impedance ZLC of the parallel LC section, as shown in the following formula: Anti-X L = wL Capacitive

[0062] Sum of admittances: Inductor admittance:

[0063] Capacitor admittance:

[0064] Total Admission:

[0065] The total impedance sub-unit is used in series with a resistor to obtain the total impedance Ztotal, as shown in the following formula: Equivalent impedance

[0066]

[0067] Total impedance (R and (in series) Resistance R and After being connected in series, the total impedance is a complex summation:

[0068] Furthermore, the signal injection unit includes: The impedance analysis subunit is used to connect the AB phase grounding loop. The controller controls the excitation module to generate an excitation signal with frequency f1 while adjusting the LC module, according to the formula... Calculate the value of LC, and then calculate the impedance. : ; The analytical processing subunit is used to repeat the impedance analysis subunit operation and inject a known frequency. , ,…, Measure the corresponding impedance , ,…, .

[0069] Equation building sub-units are used to construct a system of equations: Substituting the impedance corresponding to each frequency into the formula yields n equations, where L and C are unknowns, and R is the unknown quantity: For each frequency Substitute into the formula:

[0070] We obtain a system of n equations:

[0071]

[0072] Impedance handling subunits are used to fit the value of R using the least squares method, or to simplify calculations by selecting high-frequency / low-frequency limiting cases. High-frequency limit (f→∞): The inductive reactance of the inductor L is much greater than that of the resistor, and the capacitive reactance of the capacitor C approaches 0. At this time, Z≈R.

[0073] Low-frequency limit (f→0): The inductive reactance of inductor L approaches 0, and the capacitive reactance of capacitor C approaches infinity. At this time, Z≈R.

[0074] Example 3: This embodiment also provides an electronic device, including a memory and a processor, wherein the memory is used to store one or more computer instructions, wherein the one or more computer instructions are executed by the processor to implement the method of Embodiment 1; In practical applications, the processor can be implemented as an Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Digital Signal Processing Device (DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), controller, microcontroller unit (MCU), microprocessor, or other electronic components to execute the methods described in the above embodiments.

[0075] The method implemented in this embodiment is as described in Embodiment 1.

[0076] Example 4: This embodiment also provides a computer storage medium, in which a computer program is stored, and when the computer program is executed by one or more processors, it implements the method of embodiment one. The computer-readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0077] The method implemented in this embodiment is as described in Embodiment 1.

[0078] In the several embodiments provided in this invention, it should be understood that the disclosed systems and methods can also be implemented in other ways. The system and method embodiments described above are merely illustrative.

[0079] It should be noted that, in this document, the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0080] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for evaluating a single-ended grounding system in a smart grid based on multi-frequency injection, characterized in that, include: S1, based on the measurement sensor module, signals are injected between phases of the single-ended protective grounding system through three-way power test clamps; S2, based on the excitation signal, controls the excitation signal and switches the LC module through adjustable inductors and adjustable capacitors to obtain the measurement signal; S3, by switching the LC module, the equivalent impedance is obtained using the adjustable inductor and adjustable capacitor through the admittance method; S4 assesses the grounding loop resistance by measuring the single-ended protective grounding loop resistance R.

2. The method according to claim 1, characterized in that, S1, wherein the current sensors measure the magnitude of the injected current, and the power test clamp injects and measures the voltage signal for phases AB, AC, and BC respectively in the order of signal injection.

3. The method according to claim 2, characterized in that, In S3, the equivalent impedance is obtained through the admittance method, including: S41, calculate the equivalent impedance ZLC of the parallel LC section, using the following formula: Anti-X L = wL; Capacitive ; Sum of admittances: Inductor admittance: ; Capacitor admittance: ; Total Admission: ; S42, connected in series with a resistor, yields the total impedance Ztotal, as shown in the following formula: Equivalent impedance ; Total impedance (R and (in series); Resistance R and After being connected in series, the total impedance is a complex summation: .

4. The method according to claim 3, characterized in that, In S1, the power test clamp injects and measures voltage signals for phases AB, AC, and BC respectively, according to the signal injection sequence, including: S11, connect the AB phase grounding loop, the controller controls the excitation module to generate an excitation signal with frequency f1 and simultaneously adjusts the LC module, according to the formula Calculate the value of LC, and then calculate the impedance. ; S12, repeat S11, inject at a known frequency. , ,…, Measure the corresponding impedance , ,…, ; S13, Construct a system of equations: Substitute the impedance corresponding to each frequency into the formula to obtain n equations, where L and C are unknowns, and R is the quantity to be determined: For each frequency Substitute into the formula: ； We obtain a system of n equations: ； S14, fit the value of R using the least squares method, or simplify the calculation by selecting the high-frequency / low-frequency limiting case: High-frequency limit (f→∞): The inductive reactance of the inductor L is much greater than that of the resistor, and the capacitive reactance of the capacitor C approaches 0. At this time, Z≈R; Low-frequency limit (f→0): The inductive reactance of inductor L approaches 0, and the capacitive reactance of capacitor C approaches infinity. At this time, Z≈R.

5. An evaluation device for a single-ended grounding system of a smart grid based on multi-frequency injection, characterized in that, include: The signal injection unit is used to inject signals between phases of the single-ended protective grounding system according to the excitation sensor module through three power test clamps; The signal measurement unit is used to control the excitation signal and switch the LC module according to the excitation signal through adjustable inductors and adjustable capacitors to obtain the measurement signal; Impedance analysis unit is used to obtain the equivalent impedance by means of the adjustable inductor and adjustable capacitor through the admittance method by switching the LC module; The grounding assessment unit is used to assess the resistance of a grounding loop by measuring the resistance R of a single-ended protective grounding loop.

6. The apparatus according to claim 5, characterized in that, In the signal injection unit, the current sensors measure the magnitude of the injected current, and the power test clamp injects and measures the voltage signal for phases AB, AC, and BC respectively, according to the signal injection sequence.

7. The apparatus according to claim 6, characterized in that, In the impedance analysis unit, the equivalent impedance is obtained through the admittance method, including: The equivalent impedance sub-unit is used to calculate the equivalent impedance ZLC of the parallel LC section, as shown in the following formula: Anti-X L = wL; Capacitive ; Sum of admittances: Inductor admittance: ; Capacitor admittance: ; Total Admission: ; The total impedance sub-unit is used in series with a resistor to obtain the total impedance Ztotal, as shown in the following formula: Equivalent impedance ; Total impedance (R and (in series); Resistance R and After being connected in series, the total impedance is a complex summation: .

8. The apparatus according to claim 7, characterized in that, The signal injection unit includes: The impedance analysis subunit is used to connect the AB phase grounding loop. The controller controls the excitation module to generate an excitation signal with frequency f1 while adjusting the LC module, according to the formula... Calculate the value of LC, and then calculate the impedance. : ； The analytical processing subunit is used to repeat the impedance analysis subunit operation and inject a known frequency. , ,…, Measure the corresponding impedance , ,…, ; Equation building sub-units are used to construct a system of equations: Substituting the impedance corresponding to each frequency into the formula yields n equations, where L and C are unknowns, and R is the unknown quantity: For each frequency Substitute into the formula: ； We obtain a system of n equations: ； Impedance handling subunits are used to fit the value of R using the least squares method, or to simplify calculations by selecting high-frequency / low-frequency limiting cases. High-frequency limit (f→∞): The inductive reactance of the inductor L is much greater than that of the resistor, and the capacitive reactance of the capacitor C approaches 0. At this time, Z≈R; Low-frequency limit (f→0): The inductive reactance of inductor L approaches 0, and the capacitive reactance of capacitor C approaches infinity. At this time, Z≈R.

9. An electronic device, characterized in that, The system includes a memory and a processor, the memory being used to store one or more computer instructions, wherein the one or more computer instructions, when executed by the processor, implement the method as described in any one of claims 1-4.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, is used to implement the method as described in any one of claims 1-4.

Images