A method, apparatus, and electronic equipment for determining ground parameters of a power distribution system.

Abstract

This invention discloses a method, apparatus, and electronic device for determining the ground parameters of a power distribution system. The method includes: injecting voltages of different amplitudes twice into the neutral point using a voltage injection device, measuring the output voltage of the voltage source and the injected voltage at the neutral point for each injection; and calculating the inductance of the arc suppression coil and the ground parameters of the power distribution system based on the measured voltages from the two different injections. The ground parameters include ground conductance and ground capacitance. This invention solves the technical problem in related technologies where the determination of ground parameters of a power distribution system is inaccurate.

Description

Technical Field

[0001] This invention relates to the field of power distribution systems, and more specifically, to a method, apparatus, and electronic device for determining ground parameters of a power distribution system. Background Technology

[0002] Ground parameters can characterize the electrical characteristics between the power distribution system lines and the ground. Accurate measurement of ground parameters is crucial for the operational safety of the power distribution system. However, in related technologies, there are technical problems with the inaccurate determination of ground parameters of the power distribution system.

[0003] There is currently no effective solution to the above problems. Summary of the Invention

[0004] This invention provides a method, apparatus, and electronic device for determining the ground parameters of a power distribution system, in order to at least solve the technical problem in the related art where the determination of the ground parameters of a power distribution system is inaccurate.

[0005] According to one aspect of the present invention, a method for determining the ground parameters of a power distribution system is provided, wherein the neutral point of the power distribution system is grounded via an arc suppression coil, wherein a voltage injection device for injecting voltage into the neutral point is provided, the voltage injection device comprising a voltage source, a resistor, and an injection transformer connected in a series circuit of the voltage source and the resistor, the method comprising: injecting voltages of different amplitudes into the neutral point twice sequentially through the voltage injection device, measuring the output voltage of the voltage source and the injected voltage of the neutral point for each injection; and calculating the inductance of the arc suppression coil and the ground parameters of the power distribution system based on the voltages measured during the two different injections, wherein the ground parameters include ground conductance and ground capacitance.

[0006] Optionally, the voltage source is obtained from the voltage of the power distribution system bus through a grounding transformer.

[0007] Optionally, the resistors include: a first resistor R1, a second resistor R2, and a third resistor R3; the voltage source, the first resistor R1, the second resistor R2, and the third resistor R3 are connected in series to form a loop, the secondary side of the injection transformer is connected in parallel across the two ends of the third resistor R3, and the primary side of the injection transformer is connected between the neutral point and ground.

[0008] Optionally, the first resistor R1 and the third resistor R3 are adjustable resistors, and the second resistor R2 is a protective resistor. The voltage amplitude injected into the neutral point by the voltage injection device can be adjusted by adjusting the first resistor R1 and / or the third resistor R3.

[0009] Optionally, based on the voltages measured during two different injections, the inductance of the arc suppression coil and the capacitance to ground in the ground parameter are calculated, including:

[0010]

[0011] in, This indicates the operation of taking the imaginary part; This refers to the number of turns injected into the primary side of the transformer; This refers to the number of turns injected into the secondary side of the transformer; It is the voltage source output voltage measured during the first neutral point injection; It is the voltage source output voltage measured during the second neutral point injection; It is the neutral point injection voltage measured during the first neutral point injection; It is the neutral point injection voltage measured during the second neutral point injection; It is the resistance value of the first resistor R1 during the first neutral point injection; It is the resistance value of the first resistor R1 during the second neutral point injection; Let R2 be the resistance value of the second resistor. It is the resistance value of the third resistor R3 during the first neutral point injection; It is the resistance value of the third resistor R3 during the second neutral point injection; It is the angular frequency corresponding to the power frequency; Indicates the inductance of the arc suppression coil; This refers to the capacitance to ground in the ground parameters. It represents the imaginary unit.

[0012] Optionally, the ground conductance in the ground parameters is calculated based on the voltages measured during two different injections, including:

[0013]

[0014] in, This indicates the operation of taking the real part; This refers to the number of turns injected into the primary side of the transformer; This refers to the number of turns injected into the secondary side of the transformer; It is the output voltage of the voltage source measured during any neutral point injection; It is the neutral point injection voltage measured during any neutral point injection; The resistance value of the first resistor R1 during any neutral point injection; Let R2 be the resistance value of the second resistor. The resistance value of the third resistor R3 during any neutral point injection; It is the angular frequency corresponding to the power frequency; It is the inductance of the arc suppression coil; Represents the imaginary unit; It indicates electrical conductance to ground.

[0015] Optionally, the step of calculating the inductance of the arc suppression coil and the ground parameters of the power distribution system based on the voltages measured by the two different injections includes: determining the three-phase lines corresponding to the neutral point; determining the phase voltage correlation relationship corresponding to the three-phase lines; and calculating the inductance of the arc suppression coil and the ground parameters of the power distribution system based on the phase voltage correlation relationship and the voltages measured by the two different injections.

[0016] Optionally, before injecting voltages of different amplitudes into the neutral point twice via the voltage injection device, and measuring the output voltage of the voltage source and the injected voltage at the neutral point for each injection, the method further includes: determining a voltage stabilization period corresponding to the output voltage; determining multiple candidate voltages corresponding to the neutral point within the voltage stabilization period; determining the duration corresponding to each of the multiple candidate voltages; and determining the injected voltage at the neutral point based on the duration corresponding to each of the multiple candidate voltages and the multiple candidate voltages.

[0017] According to one aspect of the present invention, a device for determining the ground parameters of a power distribution system is provided, comprising: a first determining module, configured to inject voltages of different amplitudes into the neutral point of the power distribution system twice via a voltage injection device when the neutral point is grounded through an arc suppression coil, wherein the output voltage of a voltage source and the injected voltage of the neutral point are measured for each injection, wherein a voltage injection device for injecting voltage into the neutral point is provided at the neutral point, the voltage injection device comprising a voltage source, a resistor, and an injection transformer connected in a series circuit of the voltage source and the resistor; and a second determining module, configured to calculate the inductance of the arc suppression coil and the ground parameters of the power distribution system based on the voltages measured during the two different injections, wherein the ground parameters include ground conductance and ground capacitance.

[0018] According to one aspect of the present invention, an electronic device is provided, comprising: a processor; and a memory for storing processor-executable instructions; wherein the processor is configured to execute the instructions to implement the method for determining ground parameters of a power distribution system as described in any of the preceding claims.

[0019] In this embodiment of the invention, the neutral point of the power distribution system is grounded via an arc suppression coil, and a voltage injection device consisting of a voltage source, a resistor, and an injection transformer is installed at the neutral point. This device injects voltages of different amplitudes into the neutral point twice, simultaneously measuring the output voltage of the voltage source and the injected voltage at the neutral point for each injection. Based on the two sets of measured voltage data, the inductance of the arc suppression coil and the ground conductance and capacitance of the power distribution system are calculated. This allows for precise active voltage excitation of the neutral point using a dedicated voltage injection device. By obtaining multiple sets of valid measurement data through two voltage injections of different amplitudes, and combining the measured data, accurate calculations of core electrical parameters are completed, avoiding calculation deviations caused by single measurement data. This achieves accurate determination of the power distribution system's ground parameters and the arc suppression coil inductance, thereby solving the technical problem in related technologies where the determination of the power distribution system's ground parameters is inaccurate. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0021] Figure 1 This is a flowchart of a method for determining ground parameters of a power distribution system according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the voltage injection device circuit in an optional embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of a ground parameter measurement model in an optional embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of a simplified model for equivalent ground parameter measurement in an optional embodiment of the present invention;

[0025] Figure 5 This is a structural block diagram of a power distribution system ground parameter determination device according to an embodiment of the present invention. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] Example 1

[0029] According to an embodiment of the present invention, an embodiment of a method for determining ground parameters of a power distribution system is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0030] Figure 1 This is a flowchart of a method for determining ground parameters of a power distribution system according to an embodiment of the present invention, such as... Figure 1 As shown, the method includes the following steps:

[0031] S102, the neutral point of the power distribution system is grounded through an arc suppression coil. A voltage injection device for injecting voltage into the neutral point is provided at the neutral point. The voltage injection device includes a voltage source, a resistor, and an injection transformer connected in the series circuit of the voltage source and the resistor. The voltage injection device injects voltages of different amplitudes into the neutral point twice in succession. The output voltage of the voltage source and the injected voltage of the neutral point are measured each time.

[0032] This involves a power distribution system, which is a system for distributing electrical energy within a power system. Specifically, the neutral point of this power distribution system is grounded via an arc suppression coil.

[0033] This involves the neutral point, which is the common connection point of the three-phase windings in the power distribution system and the potential reference point of the three-phase circuit. Specifically, the neutral point is connected to one end of the arc suppression coil, and the other end of the arc suppression coil is grounded. It is the core working node of the voltage injection device and also the key measuring point for measuring the ground parameters of the power distribution system.

[0034] This involves an arc suppression coil, which is connected between the neutral point and ground in the power distribution system. It can be used to generate an inductive current to compensate for the grounding capacitance current, extinguish the arc, and suppress overvoltage when a single-phase ground fault occurs in the power distribution system.

[0035] This involves a voltage injection device, which is an active excitation electrical measurement device configured at the neutral point of the power distribution system. The voltage injection device (also known as a flexible voltage injection device) includes a voltage source, a resistor, and an injection transformer connected in the series circuit of the voltage source and the resistor. It can accurately inject power frequency voltages of different amplitudes into the neutral point, providing excitation signals for the calculation of the power distribution system's ground parameters (ground conductance, ground capacitance) and the inductance of the arc suppression coil.

[0036] This involves a voltage source, which serves as the energy source for the voltage injection device. It can provide a stable power frequency voltage, thus providing a basis for injecting voltage into the neutral point.

[0037] This involves resistors, which are resistors in the series circuit of the voltage injection device. Specifically, they may include a first resistor R1, a second resistor R2, and a third resistor R3, which are connected in series with the voltage source to form a complete circuit.

[0038] This involves an injection transformer, which is used for voltage transformation and electrical isolation. Specifically, the secondary side of the injection transformer is connected in parallel across the two ends of the third resistor R3, and the primary side of the injection transformer is connected between the neutral point and ground.

[0039] This involves injecting voltages of different amplitudes into the neutral point twice using a voltage injection device. The output voltage of the voltage source and the injected voltage at the neutral point are measured for each injection. For the two injections, including the first and second injections, the output voltage of the voltage source and the injected voltage at the neutral point are measured for each injection. This includes measuring the output voltage of the corresponding voltage source and the injected voltage at the neutral point after the first voltage injection, and measuring the output voltage of the corresponding voltage source and the injected voltage at the neutral point after the second voltage injection.

[0040] By grounding the neutral point of the power distribution system through an arc suppression coil and installing a voltage injection device at the neutral point, which includes a voltage source, a resistor, and an injection transformer, different amplitude voltages are injected into the neutral point twice. The output voltage of the voltage source and the injected voltage at the neutral point are measured simultaneously with each injection. This allows for basic compensation for grounding faults in the power distribution system based on the arc suppression coil, and enables precise and active injection of power frequency voltages of different amplitudes into the neutral point using the hardware components of the voltage injection device.

[0041] S104. Based on the voltages measured during two different injections, calculate the inductance of the arc suppression coil and the ground parameters of the power distribution system. The ground parameters include ground conductance and ground capacitance.

[0042] This involved measuring the voltages from two different injections: specifically, after the first injection, measuring the output voltage of the corresponding voltage source and the injection voltage at the neutral point; and after the second injection, measuring the output voltage of the corresponding voltage source and the injection voltage at the neutral point.

[0043] This involves ground parameters, which are parameters that characterize the electrical characteristics between the power distribution system lines and the ground, including ground conductance and ground capacitance.

[0044] By injecting voltages of different amplitudes twice and simultaneously measuring the corresponding electrical parameters, two sets of valid and different voltage measurement data are obtained. This provides a real and effective original measurement basis for subsequent calculations of key ground parameters such as the inductance of the arc suppression coil and the ground conductance and ground capacitance of the power distribution system, ensuring the accuracy and feasibility of subsequent parameter calculations.

[0045] Through the steps S102-S104 described above, the neutral point of the power distribution system is grounded via an arc suppression coil, and a voltage injection device consisting of a voltage source, a resistor, and an injection transformer is installed at the neutral point. This device injects voltages of different amplitudes into the neutral point twice, simultaneously measuring the output voltage of the voltage source and the injected voltage at the neutral point for each injection. Based on the two sets of measured voltage data, the inductance of the arc suppression coil and the ground conductance and capacitance of the power distribution system are calculated. This allows for precise active voltage excitation of the neutral point using a dedicated voltage injection device. By obtaining multiple sets of effective measurement data through two voltage injections of different amplitudes, and combining this data with the measured data, accurate calculations of core electrical parameters are completed, avoiding calculation deviations caused by single measurement data. This achieves accurate determination of the power distribution system's ground parameters and the arc suppression coil inductance, thus solving the technical problem of inaccurate determination of the power distribution system's ground parameters in related technologies.

[0046] As an alternative embodiment, the voltage source is obtained from the voltage of the power distribution system bus via a grounding transformer.

[0047] This involves a grounding transformer, which is a transformer in the power distribution system that realizes voltage conversion. It can convert the high-voltage power frequency voltage of the power distribution system bus into a low-voltage power frequency voltage suitable for the operation of the voltage injection device.

[0048] This involves the power distribution system busbar, which is the core conductive trunk line for collecting, distributing and transmitting electrical energy in the power distribution system. It is the connection hub for various electrical equipment in the power distribution system and can provide a stable power frequency voltage input for obtaining voltage sources.

[0049] This involves obtaining the voltage from the distribution system busbar through a grounding transformer. Specifically, the primary side of the grounding transformer is connected to the distribution system busbar. Utilizing the transformer's turns ratio characteristics, the high-voltage power frequency voltage of the distribution system busbar is stepped down and converted into a low-voltage power frequency voltage that meets the amplitude adaptation requirements of the voltage injection device. This converted low-voltage power frequency voltage is the voltage source required by the voltage injection device.

[0050] The primary side of the grounding transformer is connected to the power distribution system bus, which serves as the power hub of the power distribution system. The transformation ratio characteristics of the grounding transformer are used to step down the high-voltage power frequency voltage of the bus and convert it into a low-voltage power frequency voltage suitable for the operation of the voltage injection device. This voltage is used as the voltage source for the voltage injection device. It can directly obtain a stable voltage input from the power distribution system's own bus, ensuring that the amplitude of the voltage source accurately matches the operating requirements of the voltage injection device. This provides a stable and suitable energy source for the voltage injection device to accurately inject voltages of different amplitudes into the neutral point, ensuring the smooth implementation of the voltage injection operation.

[0051] As an optional embodiment, the resistors include: a first resistor R1, a second resistor R2, and a third resistor R3; the voltage source, the first resistor R1, the second resistor R2, and the third resistor R3 are connected in series to form a loop, the secondary side of the injection transformer is connected in parallel across the two ends of the third resistor R3, and the primary side of the injection transformer is connected between the neutral point and ground.

[0052] This involves a first resistor R1, which is an adjustable resistor in the series circuit of the voltage injection device. It is a key component for adjusting the amplitude of the injected voltage and can adjust the total impedance and voltage division of the circuit by changing its own resistance in conjunction with other resistors.

[0053] This involves a second resistor R2, which is a protective resistor in the series circuit of the voltage injection device. It is used to limit the current in the circuit and prevent overcurrent damage to other electrical components in the device.

[0054] This involves a third resistor, R3, which is an adjustable resistor in the series circuit of the voltage injection device. It is both a voltage divider element in the circuit and a key component that works in conjunction with the secondary side of the injection transformer. The input voltage of the injection transformer can be changed by adjusting its resistance value.

[0055] This involves a voltage source, a first resistor R1, a second resistor R2, and a third resistor R3 connected in series to form a circuit. Specifically, the output terminal of the voltage source is electrically connected to the first resistor R1, the second resistor R2, and the third resistor R3 in sequence to form a closed series electrical circuit, so that the current output by the voltage source can flow through each resistor in sequence to realize voltage division and current regulation of the circuit.

[0056] This involves the secondary side, which is the low-voltage winding of the injection transformer. It is the side connected in series with the voltage injection device circuit and can receive the electrical signals from the circuit and transmit them to the primary side.

[0057] This involves the primary side, which is the high-voltage winding of the injection transformer. It is the side connected to the neutral point and ground in the power distribution system and can convert the voltage transmitted from the secondary side and apply it between the neutral point and ground.

[0058] This involves connecting the secondary side of the injection transformer in parallel across the two ends of the third resistor R3, and connecting the primary side of the injection transformer between the neutral point and ground. Specifically, the two terminals of the secondary side of the injection transformer are electrically connected to the two ends of the third resistor R3 to obtain the voltage drop across the third resistor R3. At the same time, one end of the primary side of the injection transformer is connected to the neutral point of the power distribution system, and the other end is connected to the ground, so as to realize the voltage conversion of the secondary side and the injection of voltage into the neutral point.

[0059] The voltage injection device is configured with resistors R1, R2, and R3, which are connected in series with the voltage source to form a closed loop. The secondary side of the injection transformer is connected in parallel across the third resistor R3, and the primary side is connected between the neutral point and ground. The second resistor R2 can limit the loop current to prevent overcurrent damage to the device components. The adjustable characteristics of the first resistor R1 and the third resistor R3 are used to adjust the loop voltage division and total impedance, so that the voltage division of the third resistor R3 can be accurately used as the input voltage of the secondary side of the injection transformer.

[0060] As an optional embodiment, the first resistor R1 and the third resistor R3 are adjustable resistors, and the second resistor R2 is a protective resistor. The voltage amplitude injected into the neutral point by the voltage injection device can be adjusted by adjusting the first resistor R1 and / or the third resistor R3.

[0061] This involves adjustable resistors, which are resistive elements with adjustable resistance values. By changing their own resistance values, the voltage division, total impedance, and current in the circuit can be adjusted.

[0062] This involves a protective resistor, which is a component used to limit the current in the circuit and prevent overcurrent from damaging the voltage source.

[0063] This involves adjusting the first resistor R1 and / or the third resistor R3 to adjust the injection voltage amplitude from the voltage injection device to the neutral point, including:

[0064] Adjust the first resistor R1 to adjust the voltage amplitude (i.e., voltage amplitude) injected into the neutral point by the voltage injection device.

[0065] Adjust the third resistor R3 to adjust the voltage amplitude injected into the neutral point by the voltage injection device;

[0066] Adjust the first resistor R1 and the third resistor R3 to adjust the voltage amplitude injected into the neutral point by the voltage injection device.

[0067] By setting the second resistor R2 as a protective resistor, overcurrent in the circuit can be limited, preventing the voltage source from being damaged by excessive current and providing basic overcurrent protection for the entire voltage injection device circuit. By using the first resistor R1 and the third resistor R3 as adjustable resistors, dual control of the total circuit impedance and the voltage division of the third resistor R3 can be achieved. Compared to setting only the third resistor R3 as an adjustable resistor, adding an adjustable first resistor R1 can further refine the voltage division adjustment accuracy of the circuit, making the voltage division adjustment range of the third resistor R3 wider and the value more precise. By adjusting the first resistor R1 alone, adjusting the third resistor R3 alone, or adjusting both simultaneously, the input voltage on the secondary side of the injection transformer can be flexibly adjusted, thereby precisely controlling the injection voltage amplitude to the neutral point and stably achieving the operational requirements of injecting different amplitude voltages to the neutral point twice, ensuring the accuracy and flexibility of voltage injection.

[0068] As an optional embodiment, the inductance of the arc suppression coil and the capacitance to ground in the ground parameters are calculated based on the voltages measured during two different injections, including:

[0069]

[0070] in, This indicates the operation of taking the imaginary part; This refers to the number of turns injected into the primary side of the transformer; This refers to the number of turns injected into the secondary side of the transformer; It is the voltage source output voltage measured during the first neutral point injection; It is the voltage source output voltage measured during the second neutral point injection; It is the neutral point injection voltage measured during the first neutral point injection; It is the neutral point injection voltage measured during the second neutral point injection; It is the resistance value of the first resistor R1 during the first neutral point injection; It is the resistance value of the first resistor R1 during the second neutral point injection; Let R2 be the resistance value of the second resistor. It is the resistance value of the third resistor R3 during the first neutral point injection; It is the resistance value of the third resistor R3 during the second neutral point injection; It is the angular frequency corresponding to the power frequency; Indicates the inductance of the arc suppression coil; This refers to the capacitance to ground in the ground parameters. It represents the imaginary unit.

[0071] This involves the power frequency, which is the operating frequency of AC power in the power distribution system. It is the rated frequency of the power distribution system during normal operation and can be 50Hz.

[0072] By substituting the measured voltage and resistance values ​​corresponding to the two voltage injections, along with parameters such as the transformer turns ratio and power frequency, into the set of formulas for calculating the capacitance to ground, and performing the imaginary part operation on the complex quantities in the formulas to complete the corresponding numerical calculations, a set of equations about the inductance of the arc suppression coil and the capacitance to ground can be constructed based on the measurement data of the two different injections. By solving this set of equations to eliminate unknowns, the inductance of the arc suppression coil and the capacitance to ground of the power distribution system can be accurately calculated. This ensures that even when the arc suppression coil tap position is unknown, accurate inductance and capacitance to ground values ​​can be obtained based on measured parameters and quantitative formulas, providing core computational support for the complete determination of the ground parameters of the power distribution system.

[0073] As an optional embodiment, the ground conductance in the ground parameters is calculated based on the voltages measured from two different injections, including:

[0074]

[0075] in, This indicates the operation of taking the real part; This refers to the number of turns injected into the primary side of the transformer; This refers to the number of turns injected into the secondary side of the transformer; It is the output voltage of the voltage source measured during any neutral point injection; It is the neutral point injection voltage measured during any neutral point injection; The resistance value of the first resistor R1 during any neutral point injection; Let R2 be the resistance value of the second resistor. The resistance value of the third resistor R3 during any neutral point injection; It is the angular frequency corresponding to the power frequency; It is the inductance of the arc suppression coil; Represents the imaginary unit; It indicates electrical conductance to ground.

[0076] This formula is rigorously derived based on the circuit topology of the power distribution system with the neutral point grounded through the arc suppression coil and the equivalent admittance theory. It establishes a quantitative relationship between the real part of the three-phase equivalent admittance to ground and the single-phase conductance to ground, and incorporates actual circuit characteristics such as the transformer turns ratio, loop resistance voltage division, and power frequency complex impedance calculation. The calculation logic closely matches the actual electrical conditions of the power distribution system, and the substituted voltage and resistance are actual measured effective parameters, while the arc suppression coil inductance is the result of accurate calculation in the early stage. By taking the real part of the complex quantity, the core parameters characterizing the conductance of the power distribution system to ground can be accurately extracted, and the conductance to ground can be accurately calculated.

[0077] As an optional embodiment, the inductance of the arc suppression coil and the ground parameters of the power distribution system are calculated based on the voltages measured by the two different injections, including: determining the three-phase lines corresponding to the neutral point; determining the phase voltage correlations corresponding to the three-phase lines; and calculating the inductance of the arc suppression coil and the ground parameters of the power distribution system based on the phase voltage correlations and the voltages measured by the two different injections.

[0078] This involves a three-phase line, which is the neutral point A, B, and C three-phase distribution line in the power distribution system. It is the core line for transmitting electrical energy in the power distribution system.

[0079] This involves the phase voltage correlation, which is the inherent electrical correlation characteristic between the phase voltages of the three-phase lines A, B, and C corresponding to the neutral point in the power distribution system. Specifically, it is manifested in the symmetrical relationship between the amplitude and phase of the three-phase voltages, and the vector sum of the three-phase voltages is zero, which can be expressed as:

[0080]

[0081] in, , , These are the voltages of phases A, B, and C, respectively.

[0082] By determining the phase voltage correlation with the three-phase line, the circuit model can be effectively simplified, redundant unknowns can be eliminated, and a simple set of equations containing only the arc suppression coil inductance and ground parameters can be established. This allows for accurate calculation of unknowns without additional measurements or the introduction of external assumptions, avoiding calculation errors and deviations caused by model complexity or too many unknowns, and improving the accuracy and reliability of the calculation results.

[0083] As an optional embodiment, before injecting voltages of different amplitudes into the neutral point twice by means of a voltage injection device, and measuring the output voltage of the voltage source and the injected voltage of the neutral point for each injection, the method further includes: determining a voltage stabilization period corresponding to the output voltage; determining multiple candidate voltages corresponding to the neutral point within the voltage stabilization period; determining the duration corresponding to each of the multiple candidate voltages; and determining the injected voltage of the neutral point based on the duration corresponding to each of the multiple candidate voltages and the multiple candidate voltages.

[0084] This includes the voltage stabilization period, which is the time period after voltage injection during which the output voltage no longer fluctuates drastically and the amplitude and phase remain stable. This is the period during which valid and reliable measurement data can be obtained.

[0085] This involves multiple candidate voltages, which are multiple sets of voltage sampling values ​​collected in real time at the neutral point during the voltage stabilization period. These are used for subsequent screening and determination of the final injection voltage.

[0086] This involves a duration period, which is the length of time during which each candidate voltage can remain stable, used to determine whether the voltage value is stable and valid.

[0087] By first determining the voltage stability period, interference from transient voltage fluctuations can be eliminated, and only stable and reliable data intervals can be selected. Then, multiple candidate voltages within this period are collected and their durations are determined, enabling multi-sampling point stability verification of the neutral point voltage. Based on the duration and candidate voltages, the injection voltage is determined, allowing the selection of the effective value with the longest holding time and the most stable amplitude. Instantaneous jumps and noise sampling are eliminated, thereby significantly improving the measurement accuracy of the neutral point injection voltage and avoiding calculation distortion caused by voltage fluctuations and instantaneous interference. This provides reliable raw data for the subsequent accurate solution of arc suppression coil inductance and ground parameters.

[0088] Based on the above embodiments and optional embodiments, an optional implementation method is provided, which is described in detail below.

[0089] In related technologies, ground parameters can characterize the electrical characteristics between the power distribution system lines and the ground. Accurate measurement of ground parameters is crucial for the operational safety of the power distribution system. However, in related technologies, there is a technical problem of inaccurate determination of the ground parameters of the power distribution system.

[0090] There is currently no effective solution to the above problems.

[0091] In view of this, an optional embodiment of the present invention provides a method for determining the ground parameters of a power distribution system, which can also be called a method for measuring the grounding parameters of a power distribution system based on flexible voltage injection, and can effectively solve the above-mentioned technical problems.

[0092] Figure 2 This is a schematic diagram of the voltage injection device circuit in an optional embodiment of the present invention. Figure 3 This is a schematic diagram of a ground parameter measurement model in an optional embodiment of the present invention, such as... Figure 2 and Figure 3 As shown, a detailed description follows.

[0093] A power distribution system grounded through a neutral point via an arc suppression coil includes:

[0094] Constructing a flexible voltage injection device: Connecting an injection transformer to the series circuit of the voltage source and the resistor to inject voltage into the neutral point;

[0095] A flexible voltage injection device was used to inject voltages of different amplitudes into the neutral point twice. The output voltage of the voltage source and the injected voltage at the neutral point were measured for each injection.

[0096] Then, based on the voltages measured during the two different injections, the inductance of the arc suppression coil and the ground parameters of the power distribution system are calculated: ground conductance and ground capacitance.

[0097] Specifically, the constructed flexible voltage injection device includes: a voltage source, a first resistor R1, a second resistor R2, a third resistor R3, and an injection transformer; the voltage source, the first resistor R1, the second resistor R2, and the third resistor R3 are connected in series to form a loop, the secondary side of the injection transformer is connected in parallel across the two ends of the third resistor R3, and the primary side of the injection transformer is connected between the neutral point and ground.

[0098] The voltage source is obtained by converting the 10kV power frequency voltage of the distribution system bus to a lower 1140V voltage through a grounding transformer; both the first resistor R1 and the third resistor R3 are adjustable precision resistors. In the series circuit of the voltage source, the amplitude of the injected voltage from the flexible voltage injection device to the neutral point can be flexibly and precisely adjusted by adjusting the first resistor R1 and / or the third resistor R3.

[0099] The bus voltage of the power distribution system is connected to the primary side of the grounding transformer, and a power frequency voltage source with controllable amplitude is generated on the secondary side through transformation ratio conversion. The output voltage of this voltage source is divided by the third resistor R3 to obtain a sampling signal used for feedback regulation. The neutral point injection voltage can be flexibly changed. The amplitude is thus used to achieve active excitation and high-precision measurement of the electrical parameters of the fault circuit.

[0100] Since the ground parameters of the power distribution system are much greater than the transformer impedance, the current in the voltage source circuit is determined by the voltage and the total circuit impedance, and their relationship can be expressed as:

[0101]

[0102] in, This refers to the current in the voltage source circuit, that is, the current injected into the secondary side of the transformer; It is the voltage injected into the secondary side of the transformer; It is the resistance value of the first resistor R1 during any neutral point injection; This is the resistance value of the second resistor, R2; It is the resistance value of the third resistor R3 during any neutral point injection. It is the output voltage of the voltage source measured during any neutral point injection.

[0103] The primary current of the injection transformer can be obtained from the secondary current of the injection transformer through electromagnetic transformation based on the transformer's turns ratio.

[0104]

[0105]

[0106] in, This refers to the primary current injected into the transformer. This refers to the number of turns injected into the primary side of the transformer; This refers to the number of turns injected into the secondary side of the transformer.

[0107] To achieve high-precision monitoring of the neutral point voltage, a dedicated voltage transformer (PT) with a transformation ratio of 6062V / 100V is installed on the secondary side of the injection transformer. This transformer proportionally converts the neutral point voltage signal on the primary side into a low-voltage signal that can be acquired by the measurement and control device, thereby enabling real-time monitoring, recording, and data analysis of the neutral point voltage waveform.

[0108] Figure 4 This is a schematic diagram of a simplified model for equivalent ground parameter measurement in an optional embodiment of the present invention, such as... Figure 4 As shown, It is the neutral point injection voltage measured during any neutral point injection. That is, the voltage injected into the primary side of the transformer is the voltage to ground. Therefore, in a power distribution system where the neutral point is grounded through an arc suppression coil, the electrical circuit from the neutral point of the grounding transformer to the end of the line can be equivalent to a simplified model that includes line parameters and grounding resistance.

[0109] in, It is the sum of the three-phase capacitances to ground, expressed as:

[0110]

[0111] in, These are the capacitances of A, B, and C relative to ground.

[0112] It is the sum of the three-phase conductances to ground, expressed as:

[0113]

[0114] in, It is the relative conductance of A, B, and C to ground.

[0115] It is generally believed that the parameters of a three-phase line relative to ground remain symmetrical, that is:

[0116]

[0117] Then we have the formula:

[0118]

[0119] in, , , These are the voltages of phases A, B, and C, respectively. It is the inductance (i.e., the equivalent inductance) of the arc suppression coil. , These are the capacitance and conductance to ground of each phase line, without considering harmonic components.

[0120] The three-phase parameters are symmetrical, that is... The following are listed:

[0121]

[0122] Joint ,and Then we have:

[0123]

[0124] Right now:

[0125]

[0126] Based on this, if , The ground parameters of the power distribution system, as measured by the measuring device, are as follows:

[0127]

[0128] Conductivity to ground of each phase line for:

[0129]

[0130] in, This represents the equivalent admittance of the three-phase power distribution system to ground. This indicates the operation of taking the real part; This refers to the number of turns injected into the primary side of the transformer; This refers to the number of turns injected into the secondary side of the transformer; It is the output voltage of the voltage source measured during any neutral point injection; It is the neutral point injection voltage measured during any neutral point injection; The resistance value of the first resistor R1 during any neutral point injection; Let R2 be the resistance value of the second resistor. The resistance value of the third resistor R3 during any neutral point injection; It is the angular frequency corresponding to the power frequency; It is the inductance of the arc suppression coil; Represents the imaginary unit; It indicates electrical conductance to ground.

[0131] If the arc suppression coil's position is known, that is, the inductance of the arc suppression coil... Given the information, the capacitance to ground of each phase of the line can be calculated:

[0132]

[0133] If the arc suppression coil's tap position is unknown, by adjusting the resistance values ​​of the first resistor R1 and the third resistor R3, different voltages are injected into the neutral point twice. By measuring the neutral point injection voltage and the voltage source output voltage obtained from the two different resistance values, a set of equations can be constructed as follows:

[0134]

[0135] in, This indicates the operation of taking the imaginary part; This refers to the number of turns injected into the primary side of the transformer; This refers to the number of turns injected into the secondary side of the transformer; It is the voltage source output voltage measured during the first neutral point injection; It is the voltage source output voltage measured during the second neutral point injection; It is the neutral point injection voltage measured during the first neutral point injection; It is the neutral point injection voltage measured during the second neutral point injection; It is the resistance value of the first resistor R1 during the first neutral point injection; It is the resistance value of the first resistor R1 during the second neutral point injection; Let R2 be the resistance value of the second resistor. It is the resistance value of the third resistor R3 during the first neutral point injection; It is the resistance value of the third resistor R3 during the second neutral point injection; It is the angular frequency corresponding to the power frequency; Indicates the inductance of the arc suppression coil; This represents the capacitance to ground (i.e., the capacitance to ground of each phase line) in the ground parameters. It represents the imaginary unit.

[0136] Solving the above system of equations will yield the inductance of the arc suppression coil. The specific values ​​of the capacitance to ground for each phase line.

[0137] The above optional implementation methods can achieve at least the following beneficial effects:

[0138] (1) Compared with related technologies, the present invention is based on the method for measuring the ground parameters of the power distribution system using flexible voltage injection. In the case of unknown tap position of the arc suppression coil, the neutral point voltage is monitored in real time by high-precision voltage and current transformers, forming a closed-loop detection architecture of "active excitation-synchronous measurement". This can accurately solve the ground parameters of the power distribution system and the inductance value of the arc suppression coil at the unknown tap position, thereby improving the safety and continuity of the power supply of the power distribution network.

[0139] (2) Compared with related technologies, the present invention grounds the neutral point of the power distribution system through an arc suppression coil and sets a voltage injection device consisting of a voltage source, a resistor and an injection transformer at the neutral point. Through this device, voltages of different amplitudes are injected into the neutral point twice and the output voltage of the voltage source and the injected voltage of the neutral point are measured simultaneously for each injection. Then, based on the two sets of measured voltage data, the inductance of the arc suppression coil and the ground conductance and ground capacitance of the power distribution system are calculated. It can achieve accurate active voltage excitation of the neutral point by relying on a dedicated voltage injection device. Multiple sets of effective measurement data are obtained through two voltage injections of different amplitudes. The core electrical parameters are accurately calculated by combining the measured data, avoiding the calculation deviation caused by a single measurement data. The accurate determination of the ground parameters of the power distribution system and the inductance of the arc suppression coil is achieved, thereby solving the technical problem in related technologies where the ground parameters of the power distribution system are not accurately determined.

[0140] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0141] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods according to the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0142] Example 2

[0143] According to an embodiment of the present invention, an apparatus for implementing the above-described method for determining ground parameters of a power distribution system is also provided. Figure 5 This is a structural block diagram of a power distribution system ground parameter determination device according to an embodiment of the present invention, such as... Figure 5 As shown, the device includes a first determining module 502 and a second determining module 504. The device will be described in detail below.

[0144] The first determining module 502 is used to inject voltages of different amplitudes into the neutral point twice in succession through a voltage injection device when the neutral point of the power distribution system is grounded through an arc suppression coil. Each injection measures the output voltage of the voltage source and the injected voltage of the neutral point. The voltage injection device is provided at the neutral point for injecting voltage into the neutral point. The voltage injection device includes a voltage source, a resistor, and an injection transformer connected in the series circuit of the voltage source and the resistor.

[0145] The second determining module 504, connected to the first determining module 502, is used to calculate the inductance of the arc suppression coil and the ground parameters of the power distribution system based on the voltages measured by the two different injections. The ground parameters include ground conductance and ground capacitance.

[0146] It should be noted here that the first determining module 502 and the second determining module 504 mentioned above correspond to steps S102 to S104 in the method for determining the ground parameters of the power distribution system. The multiple modules and the corresponding steps are the same in terms of the instances and application scenarios implemented, but are not limited to the content disclosed in the above embodiment 1.

[0147] Example 3

[0148] According to another aspect of the present invention, an electronic device is also provided, comprising: a processor; and a memory for storing processor-executable instructions, wherein the processor is configured to execute instructions to implement the method for determining ground parameters of a power distribution system as described above.

[0149] Example 4

[0150] According to another aspect of the present invention, a computer-readable storage medium is also provided, which, when the instructions in the computer-readable storage medium are executed by a processor of an electronic device, enables the electronic device to perform the method for determining the ground parameters of a power distribution system as described above.

[0151] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0152] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0153] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0154] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0155] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0156] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0157] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for determining ground parameters of a power distribution system, characterized in that, The neutral point of the power distribution system is grounded via an arc suppression coil. A voltage injection device for injecting voltage into the neutral point is provided. The voltage injection device includes a voltage source, a resistor, and an injection transformer connected in a series circuit of the voltage source and the resistor. The method includes: The voltage injection device injects voltages of different amplitudes into the neutral point twice, and the output voltage of the voltage source and the injected voltage at the neutral point are measured for each injection. Based on the voltages measured during two different injections, the inductance of the arc suppression coil and the ground parameters of the power distribution system are calculated, wherein the ground parameters include ground conductance and ground capacitance.

2. The method according to claim 1, characterized in that, The voltage source is obtained from the voltage of the power distribution system bus through a grounding transformer.

3. The method according to claim 1, characterized in that, The resistors include: a first resistor (R1), a second resistor (R2), and a third resistor (R3); the voltage source, the first resistor (R1), the second resistor (R2), and the third resistor (R3) are connected in series to form a loop, the secondary side of the injection transformer is connected in parallel across the two ends of the third resistor (R3), and the primary side of the injection transformer is connected between the neutral point and ground.

4. The method according to claim 3, characterized in that, The first resistor (R1) and the third resistor (R3) are adjustable resistors, and the second resistor (R2) is a protective resistor. The voltage amplitude injected into the neutral point by the voltage injection device is adjusted by adjusting the first resistor (R1) and / or the third resistor (R3).

5. The method according to claim 3, characterized in that, Based on the voltages measured during two different injections, calculate the inductance of the arc suppression coil and the capacitance to ground in the ground parameters, including: in, This indicates the operation of taking the imaginary part; This refers to the number of turns injected into the primary side of the transformer; This refers to the number of turns injected into the secondary side of the transformer; It is the voltage source output voltage measured during the first neutral point injection; It is the voltage source output voltage measured during the second neutral point injection; It is the neutral point injection voltage measured during the first neutral point injection; It is the neutral point injection voltage measured during the second neutral point injection; It is the resistance value of the first resistor (R1) during the first neutral point injection; It is the resistance value of the first resistor (R1) during the second neutral point injection; This is the resistance value of the second resistor (R2); It is the resistance value of the third resistor (R3) during the first neutral point injection; It is the resistance value of the third resistor (R3) during the second neutral point injection; It is the angular frequency corresponding to the power frequency; Indicates the inductance of the arc suppression coil; This refers to the capacitance to ground in the ground parameters. It represents the imaginary unit.

6. The method according to claim 5, characterized in that, Based on the voltages measured from two different injections, the ground conductance in the ground parameters is calculated, including: in, This indicates the operation of taking the real part; This refers to the number of turns injected into the primary side of the transformer; This refers to the number of turns injected into the secondary side of the transformer; It is the output voltage of the voltage source measured during any neutral point injection; It is the neutral point injection voltage measured during any neutral point injection; The resistance value of the first resistor (R1) when injecting at any neutral point; This is the resistance value of the second resistor (R2); The resistance value of the third resistor (R3) for any neutral point injection; It is the angular frequency corresponding to the power frequency; It is the inductance of the arc suppression coil; Represents the imaginary unit; It indicates electrical conductance to ground.

7. The method according to claim 1, characterized in that, The calculation of the inductance of the arc suppression coil and the ground parameters of the power distribution system based on the voltages measured from two different injections includes: Determine the three-phase line corresponding to the neutral point; Determine the phase voltage correlation relationship corresponding to the three-phase lines; Based on the phase voltage correlation and the voltages measured during the two different injections, the inductance of the arc suppression coil and the ground parameters of the power distribution system are calculated.

8. The method according to any one of claims 1 to 7, characterized in that, Before injecting voltages of different amplitudes into the neutral point twice via the voltage injection device, and measuring the output voltage of the voltage source and the injected voltage at the neutral point for each injection, the method further includes: Determine the voltage stabilization period corresponding to the output voltage; Determine multiple candidate voltages corresponding to the neutral point during the voltage stabilization period; Determine the duration period corresponding to each of the plurality of candidate voltages; The injection voltage of the neutral point is determined based on the duration of the multiple candidate voltages and the multiple candidate voltages.

9. A device for determining ground parameters of a power distribution system, characterized in that, include: The first determining module is used to inject voltages of different amplitudes into the neutral point twice through a voltage injection device when the neutral point of the power distribution system is grounded through an arc suppression coil. Each injection measures the output voltage of the voltage source and the injected voltage at the neutral point. The voltage injection device is provided at the neutral point for injecting voltage into the neutral point. The voltage injection device includes a voltage source, a resistor, and an injection transformer connected in a series circuit of the voltage source and the resistor. The second determining module is used to calculate the inductance of the arc suppression coil and the ground parameters of the power distribution system based on the voltages measured during the two different injections, wherein the ground parameters include ground conductance and ground capacitance.

10. An electronic device, characterized in that, include: processor; Memory used to store the processor's executable instructions; The processor is configured to execute the instructions to implement the method for determining the ground parameters of the power distribution system as described in any one of claims 1 to 8.

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