10kv distribution transformer high-voltage side three-phase current measuring device and method

Abstract

This application relates to a device and method for measuring the three-phase current on the high-voltage side of a 10kV distribution transformer, specifically in the field of power measurement technology. The device includes: a main unit chassis, voltage clamps, and a current clamp; the main unit chassis encapsulates a processor and embeds a parameter input unit, connecting the voltage clamps and the current clamp through at least one input interface; the voltage clamps are connected to the main unit chassis via a voltage interface and are used to directly clamp the three-phase lines and neutral line on the low-voltage side of the transformer in the target scenario, simultaneously measuring the three-phase voltage on the low-voltage side and transmitting the low-voltage three-phase voltage to the processor; the current clamp is connected to the main unit chassis via a current interface and is used to measure the corresponding three-phase current on the low-voltage side of the transformer in the target scenario; the processor, encapsulated inside the main unit chassis, is used to determine the corresponding three-phase current information on the high-voltage side of the transformer in the target scenario based on the three-phase voltage measured by the voltage clamps and the three-phase current measured by the current clamps.

Description

Technical Field

[0001] This application relates to the field of power measurement technology, and in particular to a device and method for measuring the three-phase current on the high-voltage side of a 10kV distribution transformer. Background Technology

[0002] In the electricity consumption inspection, metering management and line loss analysis work of power supply companies, accurate measurement of the three-phase current on the high-voltage side of 10kV dedicated transformer users is the key to verifying whether the metering device is inaccurate and judging whether there is electricity theft.

[0003] Currently, when verifying the three-phase current on the high-voltage side on-site, the relevant technologies mainly use clamp-on ammeters to directly measure the current on the high-voltage side (10kV) of the distribution transformer.

[0004] However, this method requires operators to climb onto the transformer platform or enter the high-voltage distribution room, coming into close contact with high-voltage live parts, which poses an extremely high risk to personal safety. Secondly, the high-voltage side conductors usually have thick insulation layers or insulating sheaths, making it difficult to clamp the clamp meter in or to ensure a secure connection, affecting measurement accuracy. Furthermore, for some high-voltage transformers enclosed in metering boxes, the secondary side cannot be directly accessed for measurement. These problems result in low efficiency, high risk, and impracticality of on-site verification work in certain scenarios. Summary of the Invention

[0005] In view of this, this application provides a three-phase current measuring device and method for the high-voltage side of a 10kV distribution transformer. The main purpose is to improve the technical problems of related technologies that mainly use clamp-on ammeters to directly measure the current on the high-voltage side (10kV) of the distribution transformer, resulting in low efficiency, high risk and impracticality of on-site verification work in some scenarios.

[0006] In the first aspect, this application provides a three-phase current measuring device for the high-voltage side of a 10kV distribution transformer, the device comprising: a main chassis, voltage clamps, and current clamps; The main unit chassis is used to encapsulate the processor and embeds a parameter input unit. It connects to voltage clamps and current clamps through at least one input interface. The input interface includes a voltage interface and a current interface. The voltage interface is used to connect to the voltage clamp, and the current interface is used to connect to the current clamps corresponding to different measurement scenarios. The voltage clamp connects to the host chassis via a voltage interface. It is used to directly clamp the three-phase lines and neutral line on the low-voltage side of the transformer in the target scenario, simultaneously measure the three-phase voltage on the low-voltage side, and transmit the three-phase voltage on the low-voltage side to the processor. The current clamp connects to the host chassis via a current interface and is used to measure the three-phase current on the low-voltage side of the transformer in the target scenario and transmit the three-phase current on the low-voltage side to the processor. The processor, encapsulated inside the host chassis, is used to determine the high-voltage side three-phase current information corresponding to the high-voltage side of the transformer in the target scenario based on the low-voltage side three-phase voltage measured by the voltage clamp and the low-voltage side three-phase current measured by the current clamp.

[0007] Secondly, this application provides a method for measuring the three-phase current on the high-voltage side of a 10kV distribution transformer, the method comprising: The voltage clamps configured on the main chassis measure the three-phase voltage on the low-voltage side of the transformer in the target scenario. The voltage clamps are directly connected to the three-phase lines and neutral line on the low-voltage side of the transformer, and the three-phase voltage on the low-voltage side is measured simultaneously. The main chassis is used to encapsulate the processor and embeds a parameter input unit. It connects the voltage clamps and current clamps through at least one input interface. The input interface includes a voltage interface and a current interface. The voltage interface is used to connect the voltage clamps, and the current interface is used to connect the current clamps corresponding to different measurement scenarios. The three-phase current on the low-voltage side of the transformer in the target scenario is measured using the current clamp configured on the host chassis. Based on the three-phase voltage on the low-voltage side measured by the voltage clamp and the three-phase current on the low-voltage side measured by the current clamp, the three-phase current information of the high-voltage side corresponding to the high-voltage side of the transformer in the target scenario is determined.

[0008] Thirdly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method of the second aspect.

[0009] Fourthly, this application provides an electronic device, including a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor, wherein the processor executes the computer program to implement the method of the second aspect.

[0010] Fifthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the method of the second aspect.

[0011] By utilizing the above technical solution, this application provides a 10kV distribution transformer high-voltage side three-phase current measurement device and method. Compared with related technologies, this application measures the low-voltage side three-phase voltage of the transformer under the target scenario, and selects different current clamps to measure the low-voltage side three-phase current according to the target scenario. The processor in the main unit calculates the high-voltage side three-phase current, transferring the measurement point from the dangerous high-voltage side to the safe low-voltage side. It does not require direct contact with the high-voltage side, and indirectly obtains the 10kV distribution transformer high-voltage side three-phase current information by measuring the low-voltage side current, completely eliminating the risk of high-voltage operation, ensuring personnel safety, and adapting to the measurement needs of the low-voltage side primary or secondary current under different measurement scenarios, thereby improving the efficiency of on-site verification work.

[0012] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0013] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This paper shows a schematic diagram of the structure of a three-phase current measuring device on the high-voltage side of a 10kV distribution transformer provided in an embodiment of this application. Figure 2 This application illustrates an example of a Dyn11 transformer winding connection method and voltage phasor diagram provided in an embodiment of the present application. Figure 3 This application illustrates an example of a Yyn0 transformer winding connection method and voltage phasor diagram provided in an embodiment of the present application. Figure 4 This application provides an example of a three-phase voltage and current phasor diagram on the low-voltage side. Figure 5 A flowchart illustrating the three-phase current measurement method on the high-voltage side of a 10kV distribution transformer provided in this application embodiment is shown. Detailed Implementation

[0016] To better understand the above-mentioned objectives, features, and advantages of this application, the solution of this application will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0017] In residential electricity use and other scenarios, the majority of loads are single-phase devices, leading to a widespread and severe three-phase load imbalance in 10kV distribution networks. This presents a fundamental technical challenge: for common Dyn11 or Yyn0 connected 10 / 0.4 kV distribution transformers, the high-voltage side (10kV side) windings are typically delta (D) or star (Y) connected with the neutral point ungrounded. Therefore, the vector sum of the three-phase line currents on the high-voltage side must be zero at all times. However, the unbalanced current component on the low-voltage side (0.4kV side) can form a loop through the star (yn) connected neutral line (zero line). This means that when the load is three-phase unbalanced, the current on the low-voltage side cannot be directly calculated from the turns ratio (transformation ratio) to obtain the current on the high-voltage side. The amplitude and phase relationship between the two is complex and must be accurately calculated based on the specific connection method and electromagnetic relationships of the transformer.

[0018] The relevant technology, which relies on operators using clamp meters to directly measure the ammeter, has the following defects and shortcomings: 1. Extremely high safety risks: The direct measurement method requires workers to be in a high-voltage environment, which poses serious safety risks such as electric shock and falls from heights, and violates the principle of "working on the low-voltage side as much as possible" in the power safety regulations; 2. Inconvenient operation and poor applicability: The narrow space and insulation of the high-voltage side conductors make it difficult to install clamp meters and they cannot be used in all types of transformers or metering box structures. 3. Unable to perform phasor analysis: Ordinary clamp meters can only measure the effective value of current and cannot simultaneously obtain the phase information of voltage and current. The phase relationship (phasor diagram) is the core basis for judging metering wiring errors, analyzing reactive power compensation, and diagnosing faults.

[0019] To address the technical issues of inefficient and dangerous on-site verification work due to the primary use of clamp-on ammeters for direct measurement on the high-voltage side (10kV) of distribution transformers, and the impracticality of such methods in certain scenarios, this embodiment provides a three-phase current measurement device for the high-voltage side of a 10kV distribution transformer. Figure 1As shown, the device includes: a main unit chassis 1, voltage clamps 2, and current clamps 3; the main unit chassis 1 is used to encapsulate the processor 11 and embed a parameter input unit 12, and connects the voltage clamps 2 and the current clamps 3 through at least one input interface. The input interface includes a voltage interface and a current interface. The voltage interface is used to connect the voltage clamps 2, and the current interface is used to connect the current clamps 3 corresponding to different measurement scenarios; the voltage clamps 2 are connected to the main unit chassis 1 through the voltage interface, and are used to directly clamp the three-phase lines and neutral line on the low-voltage side of the transformer in the target scenario, synchronously measure the three-phase voltage on the low-voltage side, and transmit the three-phase voltage on the low-voltage side to the processor 11; the current clamps 3 are connected to the main unit chassis 1 through the current interface, and are used to measure the three-phase current on the low-voltage side of the transformer corresponding to the low-voltage side in the target scenario, and transmit the three-phase current on the low-voltage side to the processor 11; the processor 11 is encapsulated inside the main unit chassis 1, and is used to determine the three-phase current information on the high-voltage side of the transformer corresponding to the high-voltage side in the target scenario based on the three-phase voltage on the low-voltage side measured by the voltage clamps 2 and the three-phase current on the low-voltage side measured by the current clamps 3.

[0020] In specific application scenarios, the device in this embodiment can be a portable instrument, mainly comprising three parts: a voltage clamp 2, a current clamp 3, and a main unit chassis 1. The main unit chassis 1 can be used to embed a parameter input unit 12, a power switch, and an internal circuit board. The circuit board may include a processor 11. The front of the main unit chassis 1 may have an input interface area, which may include multiple input interfaces, such as at least one voltage interface on the left and at least one current interface on the right. The voltage interface can be used to connect to the voltage clamp 2, and the current interface can be used to connect to the current clamp 3 to obtain the current and voltage on the low-voltage side of the transformer in the target scenario in real time. The voltage clamp 2 and the current clamp 3 can be connected to the input interface through wires and extended to the low-voltage side circuit outside the main unit chassis 1 to realize convenient electrical quantity acquisition without the need for technicians to directly measure on the high-voltage side of the transformer.

[0021] For example, the transformer can be a 10kV distribution transformer. The voltage interface can include the low-voltage interfaces corresponding to the three-phase voltage (Ua, Ub, Uc) and neutral voltage (Un) on the low-voltage side of the transformer. These interfaces can be labeled on the main unit chassis 1. For example, four voltage interfaces can be set on the left side of the main unit chassis 1, labeled Ua, Ub, Uc, and Un respectively. Multiple voltage clamps 2 connected through the voltage interfaces can be directly clamped to the A, B, and C three-phase and neutral (N) circuits on the low-voltage side (e.g., 0.4kV) of the transformer in the target scenario to provide working power to the internal circuit of the device (using the three-phase voltage on the low-voltage side) and simultaneously measure the instantaneous waveform of the three-phase voltage on the low-voltage side without the need to measure the voltage on the high-voltage side.

[0022] Correspondingly, the current interfaces may include current measurement interfaces corresponding to the three-phase currents (Ia, Ib, Ic) on the low-voltage side of the transformer. These interfaces can be labeled on the main unit chassis 1, for example, three low-voltage current interfaces can be set on the right side of the main unit chassis 1, labeled Ia, Ib, and Ic respectively. Optionally, at least one set of different models of current clamps 3 can be configured to adapt to different measurement scenarios, eliminating the need for current measurement on the high-voltage side. For example, for measurement scenarios such as pole-mounted transformers, distribution rooms, and prefabricated transformers, three sets of current clamps 3 can be configured, such as: Group 1 (small circular aperture, rated current 5A): used for precise measurement of the secondary current of the low-voltage side current transformer (CT); The second group (circular large diameter, rated current 600A): used for direct measurement of the primary current of the low-voltage outgoing cable of the pole-mounted transformer; The third group (square large aperture, such as 1000A): used for direct measurement of the primary current of the low-voltage copper busbar in the distribution room or box-type transformer.

[0023] In some embodiments, the processor 11 can be used to receive the low-voltage side three-phase voltage measured by the voltage clamp 2 and the low-voltage side three-phase current measured by the current clamp 3 in real time, and calculate the high-voltage side three-phase current corresponding to the target scenario using a preset algorithm. The target scenario can be the current test scenario, which can be determined according to the preset transformer measurement parameters input by the technician through the parameter input unit 12. After identifying the target scenario, different calculation methods can be selected according to the test requirements of the target scenario to calculate the high-voltage side three-phase current information. The high-voltage side three-phase current information may include the high-voltage side three-phase current amplitude and the high-voltage side three-phase current phase, and is displayed through the parameter input unit 12 to guide the technician to identify and troubleshoot circuit wiring errors.

[0024] In this way, the integrated portable device proposed in this embodiment can be used to measure the three-phase voltage of the low-voltage side of the transformer under the target scenario, and different current clamps 3 can be selected according to the target scenario to measure the three-phase current of the low-voltage side. The processor 11 in the main unit chassis 1 calculates the three-phase current of the high-voltage side, and the measurement point is transferred from the dangerous high-voltage side to the safe low-voltage side without direct contact with the high-voltage side. The three-phase current information of the high-voltage side of the 10kV distribution transformer is obtained indirectly by measuring the low-voltage side current, which completely eliminates the risk of high-voltage operation, ensures personnel safety, and can adapt to the measurement needs of the primary or secondary current of the low-voltage side under different measurement scenarios, thereby improving the efficiency of on-site verification work.

[0025] Optionally, the main unit chassis 1 is also used to encapsulate the signal conversion unit 13; the signal conversion unit 13 is used to convert the analog signal of the low-voltage side three-phase voltage measured by the voltage clamp 2 into a three-phase voltage digital signal, convert the analog signal of the low-voltage side three-phase current measured by the current clamp 3 into a three-phase voltage digital signal, and send the three-phase voltage digital signal and the three-phase voltage digital signal to the processor 11.

[0026] The signal conversion unit 13 can be used to convert analog signals to digital signals. The analog signals (voltage U_L and current I_L) collected by the voltage clamp 2 and current clamp 3 are sent to the signal conditioning circuit inside the host chassis 1. The circuit is used to safely convert high voltage and high current signals into low voltage signals. After sampling by the high-speed ADC (analog-to-digital converter), the signals are converted into a digital signal sequence that can be processed by the processor 11.

[0027] Optionally, the processor 11 is used to receive the three-phase voltage digital signal and the three-phase voltage digital signal converted by the signal conversion unit 13 in real time, calculate the fundamental amplitude of the three-phase voltage, the fundamental amplitude of the current, and the phase angle on the low-voltage side, and determine the low-voltage side phasor; and determine the high-voltage side three-phase current information based on the low-voltage side phasor.

[0028] Optionally, the host chassis 1 may include a processing unit, which may include a high-performance embedded processor 11 and memory. The processor 11 is used to execute a pre-stored high-voltage side three-phase current calculation program, the calculation flow of which is as follows: Data synchronous acquisition: Real-time synchronous acquisition of three-phase voltage digital signals on the low-voltage side, such as Ua(t), Ub(t), Uc(t), and three-phase current digital signals, such as Ia(t), Ib(t), Ic(t); Fundamental component extraction: Using a digital signal processing algorithm (Fast Fourier Transform, FFT), the fundamental voltage amplitude (U_L), fundamental current amplitude (I_L), voltage phase angle (θ_U), and current phase angle (θ_I) on the low-voltage side are accurately calculated from the real-time acquired sampled data to form low-voltage side phasors. The low-voltage side phasors include the three-phase voltage phasors (U_L∠θ_U) and the current phasors (I_L∠θ_I). High-voltage side three-phase current information output: The processor 11, in conjunction with the preset transformer measurement parameters corresponding to the transformer in the target scenario, calculates the high-voltage side three-phase current phasors using the high-voltage side three-phase current calculation formula, such as I_Ha∠θ_Ha, I_Hb∠θ_Hb, and I_Hc∠θ_Hc. These high-voltage side three-phase current phasors are then output to the parameter input unit 12 for display. The entire calculation process is completed within milliseconds, achieving real-time output. The high-voltage side three-phase current calculation formula can be adapted according to the distribution transformer connection group in the preset transformer measurement parameters, and may include the high-voltage side three-phase current calculation formula for Dyn11 type transformers and the high-voltage side three-phase current calculation formula for Yyn0 type transformers.

[0029] Optionally, the processor 11 is also used to obtain the preset transformer measurement parameters corresponding to the transformer in the target scenario through the parameter input unit 12, determine the high-voltage phase difference and transformer ratio of the transformer based on the preset transformer measurement parameters, and perform high-voltage side three-phase current conversion based on the symmetrical component method and superposition principle, as well as the high-voltage side three-phase voltage and low-voltage side three-phase current, to determine the high-voltage side three-phase current information.

[0030] For example, Figure 2 The diagram shows the winding connection method and voltage phasor diagram of a Dyn11 transformer. In this type, the three-phase voltages on the high- and low-voltage sides of the Dyn11 transformer differ by 30 degrees. The high-voltage side voltage phasor is represented by the minute hand, and the low-voltage side three-phase voltage phasor is represented by the hour hand, equivalent to 11 o'clock on a clock. Hence, it is called a Dyn11 type transformer. A, B, and C represent the three-phase input terminals on the high-voltage side, and a, b, and c represent the three-phase output terminals on the low-voltage side. This refers to the three-phase voltage on the high-voltage side. This refers to the three-phase voltage on the low-voltage side. This indicates the voltage between phase A and phase B on the high-voltage side; Figure 3 The diagram shows the winding connection method and voltage phasor diagram of a Yyn0 transformer. In this diagram, the three-phase voltage difference between the high and low voltage sides of a Yyn0 transformer is 0 degrees, equivalent to clock zero, hence the name Yyn0 transformer. If the transformer connection method is Dyn-k, the transformer ratio is N, and the three-phase voltage difference between the high and low voltage sides is 30 degrees, the corresponding voltage phasor on the high voltage side can be derived from the positive / negative sequence voltage phasors on the low voltage side based on the transformer's rated ratio and the phase characteristics of the connection group. The following high-voltage side voltage phasor conversion formula can be obtained: (1) In the formula, The positive sequence voltage phasor of phase A on the high-voltage side can be the positive sequence component obtained by decomposing the three-phase voltage on the high-voltage side using the symmetrical component method, representing the amplitude and phase information of the symmetrical fundamental voltage. It can represent the negative sequence voltage phasor of phase A on the high-voltage side, and can be the negative sequence component obtained by decomposing the three-phase voltage on the high-voltage side using the symmetrical component method, reflecting the component of three-phase voltage imbalance. It can represent the positive sequence voltage phasor of phase a on the low-voltage side, which can be the positive sequence component obtained by decomposing the three-phase voltage on the low-voltage side using the symmetrical component method. It is obtained by collecting the field voltage clamp 2 and extracting the fundamental wave using FFT. It can represent the negative sequence voltage phasor of phase a on the low-voltage side, which can be the negative sequence component obtained by decomposing the three-phase voltage on the low-voltage side using the symmetrical component method, and is also obtained by field acquisition and signal processing. k This is the coefficient for linking group identifiers.

[0031] That is, the positive-sequence component of the high-voltage side lags behind the low-voltage side by 30 degrees or leads by 330 degrees, while the negative-sequence component is exactly the opposite, lagging behind by 30 degrees or leading by 330 degrees. Correspondingly, the current has the same relationship, which can be obtained as follows: (2) In the formula, It can represent the positive sequence current phasor of phase A on the high-voltage side. The positive sequence components of the three-phase current on the high-voltage side obtained by the symmetrical component method reflect the amplitude and phase of the three-phase current on the high-voltage side under symmetrical operating conditions. It can represent the negative sequence current phasor of phase A on the high-voltage side; It can represent the positive sequence current phasor of phase a on the low-voltage side, which can be the positive sequence current component acquired on the low-voltage side and processed by FFT; It can represent the negative sequence current phasor of phase a on the low-voltage side, which can be the negative sequence current component acquired on the low-voltage side and processed by FFT.

[0032] Correspondingly, since the high-voltage neutral point of the distribution transformer is not energized and there is no zero-sequence current, there is no phase-switching issue. Assuming only phase a of the distribution transformer has a load, the current in phase a on the low-voltage side... Non-zero, phase b and c currents A value of 0 means: (3) The phase currents of phases a, b, and c are converted into low-voltage side positive sequence currents using the symmetrical component method. Low-voltage side negative sequence current Low-voltage side zero-sequence current The conversion formula is as follows: (4) Substituting equation (3) into equation (4), we get: (5) According to equation (5), it can be converted into the corresponding positive sequence current of the high-voltage side. High-voltage side negative sequence current Zero-sequence current on the high-voltage side , represented as: (6) The positive sequence current on the high-voltage side is determined using the symmetrical component method. High-voltage side negative sequence current Zero-sequence current on the high-voltage side This is converted into the ABC phase current on the high-voltage side. 、 、 , can be represented as: (7) Substituting equation (6) into equation (7), we get: (8) When processor 11 detects that the transformer is a Yyn0 type transformer k =0, so the three-phase current on the high-voltage side can be obtained as: (9) When processor 11 detects that the transformer is a Dyn11 type transformer k =11, so the three-phase current on the high-voltage side can be obtained as follows: (10) Similarly, when only phase b of the distribution transformer is under load, the current in phase b on the low-voltage side is not zero, while the currents in phases a and c are zero. Therefore, the three-phase currents on the high-voltage side of the Yyn0 type transformer are: (11) Accordingly, the three-phase currents on the high-voltage side of the Dyn11 transformer can be obtained as follows: (12) When only phase c of the low-voltage side of the distribution transformer is under load, the current in phase c on the low-voltage side is not zero, while the currents in phases a and b are zero. Therefore, the three-phase currents on the high-voltage side of the Yyn0 type transformer are: (13) The three-phase current on the high-voltage side of the Dyn11 transformer is: (14) Since the distribution network circuits consist entirely of linear components, and the symmetrical component method does not involve linear transformation, the superposition principle is satisfied, and the three-phase current can be considered as the superposition of three single-phase currents. Let the load current of phase a on the low-voltage side of the distribution transformer be... Power factor phase b load current Power factor c-phase load current Power factor The voltage and current phasor relationship is as follows: Figure 4 As shown.

[0033] Furthermore, by adding equations (9), (11), and (13), we can obtain the three-phase current on the high-voltage side of the Yyn0 type transformer: (15) Furthermore, a Cartesian coordinate system can be established for voltage and current to perform phasor analysis. Figure 4 The phasor diagram of the three-phase voltage and current on the low-voltage side is shown. Based on this diagram, the coordinates of the three-phase current on the low-voltage side can be obtained as follows: (16) Substituting the coordinates from equation (16) into equation (15) for vector operations, we obtain the coordinates of the three-phase currents on the high-voltage side as follows: (17) Furthermore, by adding equations (10), (12), and (14), we can obtain the three-phase current on the high-voltage side of the Dyn11 transformer: (18) The coordinates from equation (16) can be substituted into equation (18) for vector operations to obtain the coordinates of the three-phase currents on the high-voltage side: (19) Specifically, considering the influence of the transformer excitation current, the magnitude of the excitation current varies depending on the model, capacity, and connection method of the distribution transformer. It is generally 0.6% to 2% of the transformer's rated current. The specific value can be obtained by referring to the table (Transformer Loss Technical Parameter Table). Since the transformer excitation branch is approximately a pure inductive circuit, the excitation current lags the voltage by 90 degrees. The vector sum of the three-phase currents in equations (17) and (19) with the excitation current is used to obtain the final high-voltage side three-phase current. Finally, the magnitude and phase angle of the high-voltage side current are obtained using equation (20).

[0034] (20) In the formula, z For phasors, x The x-axis is... y The vertical axis is , This refers to the phasor size (effective value). It is the phase angle.

[0035] Optionally, the parameter input unit 12 includes a display screen 121; the display screen 121 is used to directly display the effective value of the three-phase current on the high-voltage side; the display screen 121 is also used to display the high-voltage side phasor diagram corresponding to the three-phase current on the high-voltage side, the high-voltage side phasor diagram includes the three-phase voltage phasor on the low-voltage side, the low-voltage side current phasor, and the high-voltage side voltage phasor and the high-voltage side three-phase current phasor, which are used to reflect circuit wiring errors.

[0036] For example, the display screen 121 can be installed on the top of the main unit chassis 1 for human-machine interaction and measurement data display, serving as the core interface for technicians to obtain electrical quantity information and judge wiring status. The display screen 121 can be used to present the calculation results output by the processor 11 in an intuitive phasor diagram format. For example, using the Ua phase voltage as a reference (0 degrees), the low-voltage side three-phase voltage phasors, low-voltage side current phasors, and high-voltage side voltage phasors and high-voltage side three-phase current phasors can be plotted simultaneously. This vector diagram can display the amplitude and phase relationship of electrical quantities on the high and low voltage sides. Circuit wiring errors can be identified based on the deviation of the vector angle and direction from the standard state in the phasor diagram (such as a phasor angle deviating from 120°, phasor direction reversal, or abnormal phase shift). The display screen 121 can also indicate the type of wiring error through color markings or alarms. At the same time, the display screen 121 can also directly display the effective value of each phase current on the high-voltage side in digital form. This graphical display makes wiring errors (such as reversed phase sequence or reversed current polarity) immediately apparent, thereby improving the efficiency of circuit verification.

[0037] Optionally, the parameter input unit 12 further includes a touch unit 122, which includes at least one of physical buttons and a touchpad. The touch unit 122 is used to receive preset transformer measurement parameters input by the operator and transmit the preset transformer measurement parameters to the processor 11. The preset transformer measurement parameters include the distribution transformer model, capacity, connection group, transformer rated ratio, and measurement ratio.

[0038] For example, the touch unit 122 can receive key configuration parameters related to the transformer under test preset by technicians, providing basic parameters for high-voltage side electrical quantity conversion, phasor diagram drawing, and wiring error judgment. Physical buttons or a touch panel can be embedded in the top of the main unit chassis 1. The physical buttons may include directional keys, confirmation keys, function shortcut keys, etc., providing technicians with reliable operation and quick triggering functions, suitable for complex field environments; the touch panel can provide technicians with a touchable flat area, supporting gesture operations such as sliding and tapping, for refined operations such as parameter input and menu switching.

[0039] In specific application scenarios, operators can input or select the following key parameters through the touch unit 122: distribution transformer model, such as S11, S13; capacity, such as 630kVA, 1000kVA; distribution transformer connection group, such as Dyn11, Yyn0; transformer rated turns ratio, such as 10 / 0.4; measurement ratio. When measuring the secondary current of the CT, the CT turns ratio ratio needs to be input. When directly measuring the primary current, the ratio is set to 1.

[0040] In this way, this embodiment can simultaneously measure the three-phase voltage and current on the low-voltage side using voltage clamp 2 and current clamp 3. Combined with the preset transformer measurement parameters input through the parameter input unit 12 embedded in the main unit chassis 1, the processor 11 and display screen 121 encapsulated inside the main unit chassis 1 can calculate and display the current phasor on the high-voltage side and the complete phasor relationship diagram of the high and low voltage sides in real time. The operation is carried out entirely on the low-voltage side, avoiding personnel contact with high-voltage electricity, complying with safety regulations, greatly reducing operational risks, and ensuring high operational safety. There is no need for technicians to climb poles or open the high-voltage metering box; wiring can be done directly at the low-voltage terminal of the transformer or the distribution box. A single person can quickly complete the measurement preparation, greatly improving the efficiency of the verification work. It is equipped with multiple sets of non- The current clamp 3, with the same range and shape, can cover all common measurement scenarios from CT secondary current to low-voltage copper busbar primary current, making it highly adaptable. The main unit chassis 1 has a built-in high-performance processor 11, which can acquire, calculate and display data in real time, achieving "instant measurement and results" and meeting the needs of rapid on-site diagnosis. It not only displays the current value, but more importantly, it displays a phasor diagram containing phase information, providing direct and powerful graphical evidence for judging the correctness of the metering device wiring and detecting electricity theft (such as shorting the CT or changing the polarity). The measurement results are intuitive and accurate, realizing millimeter-level rapid calculation and display of the three-phase current on the high-voltage side, meeting the needs of real-time on-site verification, and providing intuitive and reliable data support for judging the accuracy of metering and investigating suspected electricity theft.

[0041] Furthermore, as a refinement and extension of the specific implementation of the above embodiments, and to fully illustrate the implementation of this embodiment, this embodiment provides a method for measuring the three-phase current on the high-voltage side of a 10kV distribution transformer, which can be applied to a three-phase current measuring device on the high-voltage side of a 10kV distribution transformer, such as... Figure 5 As shown, the method includes: Step 101: Measure the three-phase voltage of the low-voltage side of the transformer in the target scenario using the voltage clamps configured on the host chassis.

[0042] The voltage clamp is directly connected to the three-phase line and neutral line on the low-voltage side of the transformer to simultaneously measure the three-phase voltage on the low-voltage side. The main unit is used to encapsulate the processor and embed a parameter input unit. It connects the voltage clamp and the current clamp through at least one input interface. The input interface includes a voltage interface and a current interface. The voltage interface is used to connect the voltage clamp, and the current interface is used to connect the current clamp corresponding to different measurement scenarios.

[0043] In some embodiments, voltage clamps can directly measure voltage on the low-voltage side of the transformer and transmit the data to the host chassis in real time, avoiding the need for technicians to measure voltage on the high-voltage side. Optionally, the parameter input unit may include a display and a touch unit. The display can be used to display the measured low-voltage side three-phase voltage and low-voltage side three-phase current in real time, as well as the calculated high-voltage side three-phase current information, which can be displayed in vector form.

[0044] Step 102: Measure the three-phase current on the low-voltage side of the transformer in the target scenario using the current clamp configured on the host chassis.

[0045] In some embodiments, different current clamps can be configured according to different measurement scenarios, and selected for use based on the transformer under test in the target scenario, thereby improving the adaptability of the measurement scenario. The low-voltage side three-phase current measured by the current clamp can be input to the main unit chassis through the current interface, eliminating the need for technicians to measure the current on the high-voltage side and ensuring operational safety.

[0046] Step 103: Based on the three-phase voltage on the low-voltage side measured by the voltage clamp and the three-phase current on the low-voltage side measured by the current clamp, determine the three-phase current information on the high-voltage side of the transformer in the target scenario.

[0047] In some embodiments, the processor in the host chassis can be used to calculate the high-voltage side three-phase current information corresponding to the high-voltage side of the transformer in the target scenario based on the low-voltage side three-phase voltage and low-voltage side three-phase current using a preset current conversion algorithm. This information can then be displayed on a monitor to facilitate technicians in troubleshooting circuit wiring errors.

[0048] In this way, the three-phase voltage on the low-voltage side of the transformer can be measured under the target scenario. Different current clamps can be selected according to the target scenario to measure the three-phase current on the low-voltage side. The processor in the main unit chassis calculates the three-phase current on the high-voltage side, transferring the measurement point from the dangerous high-voltage side to the safe low-voltage side. There is no need to directly contact the high-voltage side. The three-phase current information on the high-voltage side of the 10kV distribution transformer can be obtained indirectly by measuring the current on the low-voltage side, completely eliminating the risk of high-voltage operation, ensuring personnel safety, and adapting to the measurement needs of the primary or secondary current on the low-voltage side under different measurement scenarios, thereby improving the efficiency of on-site verification work.

[0049] Optionally, step 103 may specifically include: obtaining preset transformer measurement parameters corresponding to the transformer in the target scenario through the parameter input unit; determining the high-voltage phase difference and transformer ratio of the transformer based on the preset transformer measurement parameters; performing high-voltage three-phase current conversion based on the symmetrical component method and superposition principle, according to the high-voltage phase difference, transformer ratio, low-voltage three-phase voltage and low-voltage three-phase current, and finally superimposing the excitation current to determine the high-voltage three-phase current information.

[0050] In some embodiments, a Fast Fourier Transform (FFT) can be performed on the three-phase voltage digital signals to extract the fundamental amplitude and phase angle of the three-phase voltage and current on the low-voltage side, forming the three-phase voltage phasors and current phasors on the low-voltage side. Then, based on the symmetrical component method, the calculation formulas for the three-phase current on the high-voltage side when there is only a single-phase feedback load on the low-voltage side are derived. The three-phase current calculation formulas are adapted according to the distribution transformer connection group in the preset transformer measurement parameters, and may include the calculation formulas for the three-phase current on the high-voltage side of a Dyn11 type transformer and a Yyn0 type transformer. Then, based on the principle of linear superposition, the results of the three-phase current on the high-voltage side corresponding to the single-phase load are superimposed to obtain the complex plane coordinates of the three-phase current on the high-voltage side under the actual three-phase load on the low-voltage side. Finally, considering the influence of the excitation current, the excitation current and the three-phase current on the high-voltage side are vector-summed to obtain the final coordinates of the three-phase current on the high-voltage side. Based on the complex plane coordinates of the three-phase current on the high-voltage side, the effective value and phase angle of the three-phase current on the high-voltage side are calculated to form the three-phase current phasors on the high-voltage side, thus completing the 10kV... Indirect calculation of the three-phase current on the high-voltage side of a distribution transformer.

[0051] Compared with related technologies, this embodiment simultaneously measures the three-phase voltage and current on the low-voltage side using voltage clamps and current clamps. Combined with preset transformer measurement parameters input through the parameter input unit embedded in the main unit chassis, and utilizing the processor and display screen encapsulated within the main unit chassis, it calculates and displays the current phasor on the high-voltage side in real time, as well as the complete phasor relationship diagram between the high and low voltage sides. The operation is entirely performed on the low-voltage side, avoiding personnel contact with high-voltage electricity, complying with safety regulations, greatly reducing operational risks, and ensuring high operational safety. It eliminates the need for technicians to climb poles or open the high-voltage metering box; wiring is directly connected at the low-voltage terminal of the transformer or the distribution box. A single person can quickly complete the measurement preparation, significantly improving the efficiency of verification work. It is equipped with multiple sets of different ranges and... The shaped current clamp can cover all common measurement scenarios from CT secondary current to low-voltage copper busbar primary current, making it highly adaptable. The main unit has a built-in high-performance processor that can acquire, calculate, and display data in real time, achieving "instant measurement" and meeting the needs of rapid on-site diagnosis. It not only displays the current value, but more importantly, it displays a phasor diagram containing phase information, providing direct and powerful graphical evidence for judging the correctness of the metering device wiring and detecting electricity theft (such as shorting the CT or changing the polarity). The measurement results are intuitive and accurate, achieving millimeter-level rapid calculation and display of the three-phase current on the high-voltage side, meeting the needs of real-time on-site verification, and providing intuitive and reliable data support for judging the accuracy of metering and investigating suspected electricity theft.

[0052] Based on the above, Figure 5 As illustrated in the example, correspondingly, embodiments of this application also provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described... Figure 5 The example method shown.

[0053] Based on the above, Figure 5 As illustrated, correspondingly, embodiments of this application also provide a computer program product, including a computer program that, when executed by a processor, implements the above-described... Figure 5 The example method shown.

[0054] Based on this understanding, the technical solutions of the embodiments of this application can be embodied in the form of a software product. The software product can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, mobile hard drive, etc.) and includes several instructions to cause a computer device (such as a personal computer, server, or network device, etc.) to execute the methods of various implementation scenarios of this application.

[0055] Based on the above, Figure 5 To achieve the above objectives, embodiments of this application also provide an electronic device, which includes a storage medium and a processor; the storage medium is used to store a computer program; the processor is used to execute the computer program to implement the above-described... Figure 5 The method shown.

[0056] Optionally, the aforementioned electronic device may also include a user interface, a network interface, a camera, radio frequency (RF) circuitry, sensors, audio circuitry, a Wi-Fi module, etc. The user interface may include a display screen, an input unit, etc.

[0057] Those skilled in the art will understand that the physical device structure provided in this embodiment does not constitute a limitation on the physical device, and may include more or fewer components, or combine certain components, or have different component arrangements.

[0058] The storage medium may also include an operating system and a network communication module. The operating system is a program that manages the hardware and software resources of the aforementioned physical device, supporting the operation of information processing programs and other software and / or programs. The network communication module is used to enable communication between the various components within the storage medium, as well as communication with other hardware and software in the information processing physical device.

[0059] Through the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented using software plus necessary general-purpose hardware platforms, or it can be implemented using hardware. This application can simultaneously measure the three-phase voltage and current on the low-voltage side using voltage clamps and current clamps. Combined with the preset transformer measurement parameters input through the parameter input unit embedded in the main unit chassis, the processor and display screen encapsulated inside the main unit chassis can calculate and display the current phasor on the high-voltage side in real time, as well as the complete phasor relationship diagram of the high and low voltage sides. The operation is carried out entirely on the low-voltage side, avoiding personnel contact with high-voltage electricity, complying with safety regulations, greatly reducing operational risks, and ensuring high operational safety. There is no need for technicians to climb poles or open the high-voltage metering box; wiring can be directly connected at the low-voltage terminal of the transformer or the distribution box. A single person can quickly complete the measurement preparation, greatly improving the efficiency of verification work. It is equipped with multiple sets of electric... The current clamp can cover all common measurement scenarios from CT secondary current to low-voltage copper busbar primary current, making it highly adaptable. The main unit has a built-in high-performance processor that can acquire, calculate, and display data in real time, achieving "instant measurement and results" to meet the needs of rapid on-site diagnosis. It not only displays current values ​​but, more importantly, displays phasor diagrams containing phase information, providing direct and powerful graphical evidence for judging the correctness of metering device wiring and detecting electricity theft (such as shorting CT or changing polarity). The measurement results are intuitive and accurate, achieving millimeter-level rapid calculation and display of three-phase current on the high-voltage side, meeting the needs of real-time on-site verification, and providing intuitive and reliable data support for judging metering accuracy and investigating suspected electricity theft.

[0060] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the term "comprising" or any other variations thereof is 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 the element.

[0061] The above are merely specific embodiments of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to these embodiments, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A three-phase current measuring device for the high-voltage side of a 10kV distribution transformer, characterized in that, The device includes: a main unit chassis, voltage clamps, and current clamps; The host chassis is used to encapsulate the processor and embed a parameter input unit. It connects the voltage clamp and the current clamp through at least one input interface. The input interface includes a voltage interface and a current interface. The voltage interface is used to connect to the voltage clamp, and the current interface is used to connect to the current clamp corresponding to different measurement scenarios. The voltage clamp is connected to the host chassis through the voltage interface. It is used to directly clamp the three-phase line and neutral line on the low-voltage side of the transformer in the target scenario, synchronously measure the three-phase voltage on the low-voltage side, and transmit the three-phase voltage on the low-voltage side to the processor. The current clamp is connected to the host chassis through the current interface and is used to measure the three-phase current on the low-voltage side of the transformer in the target scenario and transmit the three-phase current on the low-voltage side to the processor. The processor, encapsulated inside the host chassis, is used to determine the high-voltage side three-phase current information corresponding to the high-voltage side of the transformer in the target scenario based on the low-voltage side three-phase voltage measured by the voltage clamp and the low-voltage side three-phase current measured by the current clamp.

2. The apparatus according to claim 1, characterized in that, The main unit chassis is also used to encapsulate the signal conversion unit; The signal conversion unit is used to convert the analog signal of the low-voltage side three-phase voltage measured by the voltage clamp into a three-phase voltage digital signal, convert the analog signal of the low-voltage side three-phase current measured by the current clamp into a three-phase voltage digital signal, and send the three-phase voltage digital signal and the three-phase voltage digital signal to the processor.

3. The apparatus according to claim 2, characterized in that, The processor is used to receive the three-phase voltage digital signal and the three-phase voltage digital signal converted by the signal conversion unit in real time, calculate the fundamental amplitude of the three-phase voltage, the fundamental amplitude of the current, and the phase angle on the low-voltage side, and determine the low-voltage side phasor; and determine the high-voltage side three-phase current information based on the low-voltage side phasor.

4. The apparatus according to claim 3, characterized in that, The processor is further configured to obtain preset transformer measurement parameters corresponding to the transformer in the target scenario through the parameter input unit, determine the high-voltage phase difference and transformer ratio of the transformer based on the preset transformer measurement parameters, and perform high-voltage side three-phase current conversion based on the symmetrical component method and superposition principle, as well as the high-voltage side three-phase voltage and the low-voltage side three-phase current, to determine the high-voltage side three-phase current information.

5. The apparatus according to claim 1, characterized in that, The parameter input unit includes a display screen; The display screen is used to directly display the effective value of the three-phase current on the high-voltage side; The display screen is also used to display the high-voltage side phasor diagram corresponding to the three-phase current on the high-voltage side. The high-voltage side phasor diagram includes the three-phase voltage phasor on the low-voltage side, the three-phase current phasor on the low-voltage side, and the voltage phasor and current phasor on the high-voltage side, which are used to reflect circuit wiring errors.

6. The apparatus according to claim 1, characterized in that, The parameter input unit further includes a touch unit, which includes physical buttons and a touchpad; The touch unit is used to receive preset transformer measurement parameters input by the operator and transmit the preset transformer measurement parameters to the processor. The preset transformer measurement parameters include the distribution transformer connection group, the transformer rated ratio, and the measurement ratio.

7. A method for measuring the three-phase current on the high-voltage side of a 10kV distribution transformer, characterized in that, include: The voltage clamps configured on the host chassis measure the three-phase voltage on the low-voltage side of the transformer in the target scenario. The voltage clamps are directly connected to the three-phase lines and neutral line on the low-voltage side of the transformer, simultaneously measuring the three-phase voltage on the low-voltage side. The host chassis is used to encapsulate the processor and embeds a parameter input unit. It connects the voltage clamps and the current clamps through at least one input interface. The input interface includes a voltage interface and a current interface. The voltage interface is used to connect to the voltage clamps, and the current interface is used to connect to the current clamps corresponding to different measurement scenarios. The three-phase current on the low-voltage side of the transformer in the target scenario is measured using the current clamp configured in the host chassis. Based on the three-phase voltage on the low-voltage side measured by the voltage clamp and the three-phase current on the low-voltage side measured by the current clamp, the three-phase current information on the high-voltage side of the transformer in the target scenario is determined.

8. The method according to claim 7, characterized in that, The step of determining the high-voltage side three-phase current corresponding to the measurement scenario based on the low-voltage side three-phase voltage measured by the voltage clamp and the low-voltage side three-phase current measured by the current clamp includes: The preset transformer measurement parameters corresponding to the transformer in the target scenario are obtained through the parameter input unit. The high-voltage phase difference and transformer turns ratio of the transformer are determined based on the preset transformer measurement parameters; Based on the symmetrical component method and the superposition principle, the high-voltage side three-phase current is converted according to the high-voltage phase difference, the transformer turns ratio, the low-voltage side three-phase voltage and the low-voltage side three-phase current, and the high-voltage side three-phase current information is determined.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method of any one of claims 7 to 8.

10. An electronic device comprising a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method of any one of claims 7 to 8.

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