Secondary circuit acceptance check system and check measurement method

Abstract

The invention relates to the field of loop test, in particular to a secondary loop acceptance check system and a check measurement method. The alternating current signal generator comprises an alternating current signal adjusting unit and an alternating current signal output unit, provides a signal transmission test and inputs alternating current to the primary side of the tested current transformer. The wireless phasing tester host receives verification data of the alternating current signal generator through a host data interface on the alternating current signal generator and calculates the verification data; through wireless communication connection, phase detection and data transmission are realized. According to the method, the test time is remarkably shortened, the whole process can be completed within 3 minutes according to eight windings, and the working efficiency is improved; the original two-person cooperation is changed into one-person independent operation, so that the manpower demand is reduced; the test accuracy and safety are improved, human errors and potential safety hazards are avoided, and the operation reliability of equipment is ensured; the device is small in size, light in weight and convenient to carry, is more portable and multifunctional compared with a traditional large current generator, and is suitable for on-site rapid acceptance.

Description

Technical Field

[0001] This invention relates to the field of loop testing, and in particular to a secondary loop acceptance verification system and testing and measurement method. Background Technology

[0002] Currently, existing CT testing methods mainly rely on traditional manual operations, such as verbally calibrating secondary circuit conductors, measuring insulation resistance, DC resistance, and turns ratio. These tests are usually performed collaboratively by multiple people, with one person operating the CT itself and another responding at the circuit breaker terminal box. Heavy current booster equipment is required for turns ratio testing. For example, completing the above tasks for a single CT bay (typically containing 8 windings) can take more than 2 hours. Workers need to squat, bend over, or stand for extended periods, which can easily lead to fatigue and loss of concentration, resulting in errors such as incorrect conductor calibration or data reading, directly affecting the commissioning quality and equipment accuracy.

[0003] In addition, existing CT characteristic testers have limited functionality, only capable of performing ratio tests, and cannot simultaneously handle polarity, insulation resistance, and wiring correctness. Furthermore, the testing process requires disconnecting the secondary circuit, making the operation complex, time-consuming, and potentially posing safety hazards, such as causing protection devices to fail to operate or malfunction.

[0004] Therefore, a secondary circuit acceptance and verification system and measurement method are needed that adopts a master-slave structure design to achieve real-time data interaction between the master and slave devices. This system should be able to complete the turns ratio test, insulation resistance test, and DC resistance test of all four current transformer (CT) windings simultaneously without external power supply or removal of secondary wiring, quickly identifying secondary circuit defects. It should be suitable for rapid on-site acceptance and meet the needs of the current environment. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this section, the abstract and title of the invention. Such simplifications or omissions shall not be used to limit the scope of the present invention.

[0006] Given that the traditional manual operation in the above-mentioned existing technologies is inefficient, time-consuming, and prone to errors such as incorrect wire core calibration or incorrect data reading, it directly affects the debugging quality and equipment accuracy.

[0007] Therefore, the technical problem to be solved by the present invention is to design a secondary circuit acceptance and verification system that adopts a master and slave structure, realizes real-time data interaction between the master and slave, does not require continuous two-person voice operation, and is simple and flexible to operate to meet the needs of the existing environment.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a secondary circuit acceptance and verification system, comprising, AC signal generator, wireless phase comparator main unit, and wireless phase comparator slave unit; The AC signal generator includes an AC signal conditioning unit and an AC signal output unit, providing signal transmission testing and inputting AC current to the primary side of the current transformer under test; The wireless phase comparator host receives the verification data from the AC signal generator through the host data interface on the AC signal generator and performs sampling calculations through the built-in CPU; The wireless phase comparator slave unit and the wireless phase comparator master unit are connected via wireless communication to achieve phase detection and data transmission.

[0009] As an improvement of the present invention, The AC signal generator is connected to the signal conditioning unit, and the test cable is connected through the AC signal output unit. The test cable is fixedly connected to the current transformer unit on the power supply side, the current transformer unit on the circuit breaker bushing, and the current transformer unit on the main transformer bushing, and inputs AC current to the primary side of the current transformer under test.

[0010] As an improvement of the present invention, The AC signal generator is equipped with an AC power input unit, an AC power circuit breaker, a power current display unit, a power voltage display unit, and a start / stop unit; The AC power input unit is electrically connected to the AC power circuit breaker for external power supply. The start / stop unit controls the test conditions of the AC signal generator.

[0011] As an improvement of the present invention, The wireless phase comparator main unit also includes a wireless phase comparator data plug for connecting to the main unit data interface on the AC signal generator. The wireless phase comparator slave unit is connected to the power supply side current transformer unit, the circuit breaker bushing current transformer unit, and the main transformer bushing current transformer unit respectively to provide wireless phase detection.

[0012] Given that the existing CT characteristic tester has a single function and can only perform ratio testing, it cannot simultaneously handle polarity, insulation resistance and wiring correctness. Furthermore, the testing process requires disconnecting the secondary circuit, which is complex, time-consuming and poses potential safety hazards, such as causing the protection device to fail to operate or to malfunction.

[0013] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an inspection and measurement method, comprising, The wires are connected to the secondary circuit of the current transformer. The wireless phase comparator slave and wireless phase comparator master are deployed and a master-slave communication connection is established. Start the AC signal generator and input AC current to the primary side. The wireless phase comparator host receives the secondary circuit signal and performs internal calculations. The wireless phase comparator slave unit performs tests on insulation resistance, DC resistance, and turns ratio polarity, stores the test results, and the wireless phase comparator host unit analyzes all test data and compares it with the nameplate parameters to determine the correctness of the circuit.

[0014] As an improvement of the present invention, In the polarity change test procedure, Preset reference ratio value; After inputting a 3A AC current to the primary side, the wireless phase comparator host measures the secondary side current to obtain the actual turns ratio values ​​of the four windings. The test duration is 1.5 minutes. The error rate is obtained by comparing the actual ratio value with the reference ratio value, and the error rate is determined. When the error rate is below 2%, the system operates normally and continues the process; When the error rate is higher than 2%, the system malfunctions and needs to be shut down for maintenance.

[0015] As an improvement of the present invention, In the insulation resistance test procedure, With a pre-selected test voltage of 1000V, the wireless phase comparator host tests the insulation resistance between the N phase of the four windings and the ground wire E at one time. The actual resistance value is determined based on the actual resistance value of the insulation resistance. When the actual resistance is less than 1mΩ, the system operates normally and continues the process. When the actual resistance is higher than 1mΩ, the system malfunctions and needs to be shut down for maintenance.

[0016] As an improvement of the present invention, In the DC resistance test procedure, Reserve the N-phase resistance value as a data reference; The wireless phase comparator host tests four windings at a time, compares the measured resistance values ​​of phases A, B, and C with the resistance value of phase N, and compares the resistance between A and B, B and C, and C and A. Summarize the resistance value errors obtained for each phase and determine the resistance error. When the total resistance error is less than 1 ohm, the system operates normally and continues the process; If any resistance error exceeds 1 ohm, the system malfunctions and must be shut down for maintenance.

[0017] The beneficial effects of this invention are as follows: it can significantly shorten the testing time; based on 8 windings, the entire process can be completed within 3 minutes, improving work efficiency; it reduces manpower requirements, changing from two people working together to one person operating independently, reducing labor intensity; it improves testing accuracy and safety, avoiding human error and safety hazards, and ensuring the reliability of equipment operation; the device is small in size and light in weight, making it easy to carry. Compared with traditional current boosters, it is more portable and multifunctional, suitable for rapid on-site acceptance, and fills the gap in the market for single-function testers. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a hardware architecture diagram of the secondary circuit acceptance and verification system in this invention.

[0019] Figure 2 This is a frame connection diagram of the secondary circuit acceptance and verification system in this invention.

[0020] Figure 3 This is a flowchart illustrating the verification and correction mechanism of the current testing and measurement method in this invention. Detailed Implementation

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0022] Example 1 Reference Figure 1 This embodiment provides a secondary circuit acceptance verification system.

[0023] The secondary circuit acceptance and verification system consists of an AC signal generator 1, a wireless phase comparator host 2, and a wireless phase comparator slave 3, and aims to achieve rapid acceptance and verification of the primary and secondary circuits of current transformers.

[0024] The AC signal generator 1 is the core signal source of the calibrator, with a built-in high-capacity lithium battery as its power source, supporting DC inversion to generate a stable AC current signal. Specifically, it includes an AC signal conditioning unit 11 and an AC signal output unit 12.

[0025] The AC signal conditioning unit 11 is responsible for precisely adjusting the amplitude, frequency, and phase of the generated AC signal. It can adjust the output current amplitude to a standard sine wave signal with a frequency of 50Hz to 3A, and supports fine-tuning to adapt to the testing requirements of different CT windings. The AC signal conditioning unit 11 uses a digital signal processor or similar integrated circuit to achieve fine control of the signal waveform, ensuring signal stability and thus avoiding the problems of large size and inconvenient operation caused by traditional current booster equipment.

[0026] The AC signal output unit 12 is connected to the test lead 19 and is used to output the regulated AC signal to the primary side of the CT under test. This unit is equipped with multiple output ports, supporting the simultaneous connection of components such as the power supply side current transformer 4, the circuit breaker bushing current transformer 5, the main transformer bushing current transformer 6, and the load side voltage transformer 7 to realize signal transmission testing.

[0027] The AC signal output unit 12 can also integrate safety protection mechanisms, such as overload protection and short-circuit detection, to ensure electrical safety during testing. Furthermore, the AC signal generator 1 is equipped with a host data interface 21 for transmitting verification data to the wireless phase comparator host 2 via wired or wireless means. The entire generator is small in size and lightweight, with a built-in lithium battery supporting continuous operation for 4-6 hours without the need for an external power supply, making it suitable for testing during power outages.

[0028] The wireless phase comparator host 2, acting as the data processing and control center, connects to the AC signal generator 1 via the host data interface 21 to receive raw verification data from the generator. The wireless phase comparator slave 3 is primarily used for wireless phase detection and auxiliary data transmission, connecting to the wireless phase comparator host 2 via a 2.4G wireless communication module. The wireless phase comparator slave 3 can incorporate a small sensor and antenna, placed near the CT windings, to acquire phase signals from the primary and secondary sides in real time and transmit them to the wireless phase comparator host 2. The wireless phase comparator slave 3 is compact, facilitating multi-point deployment in the field, and supports simultaneous acquisition of phase sequence and polarity data from four windings.

[0029] The AC signal output unit 12 of the AC signal generator 1 is connected to the primary side components of the CT under test via test line 19, including the power supply side current transformer 4, the circuit breaker bushing current transformer 5, the main transformer bushing current transformer 6, and the load side voltage transformer 7. The wireless phase comparator host 2 is connected to the CT secondary circuit via wire 8, and simultaneously connected to the AC signal generator 1 via the host data interface 21 to achieve data synchronization. The wireless phase comparator slave 3 is paired with the host 2 via wireless communication to form a closed-loop system.

[0030] Example 2 Reference Figures 1-2 This embodiment is based on the previous embodiment, and differs from the previous embodiment in that: The AC signal generator 1 is additionally equipped with expansion components, which, in addition to the basic signal generation function, add power management and control units, supporting flexible power supply modes and real-time monitoring, including AC power input unit 13, AC power circuit breaker 14, power current display unit 15, power voltage display unit 16 and start / stop unit 17.

[0031] The AC power input unit 13 adopts a standard three-phase or single-phase socket interface, which can support external AC power input and provide a backup power supply option. When the built-in lithium battery of the AC signal generator 1 is low, it can seamlessly switch to external power to ensure continuous testing for a long time. The AC power circuit breaker 14 acts as a safety circuit breaker, electrically connected to the AC power input unit 13, and has built-in overload and short-circuit protection functions to automatically cut off the power supply to prevent equipment damage or electrical accidents.

[0032] The power supply current display unit 15 and the power supply voltage display unit 16 can each use a digital LED display screen to monitor the current and voltage of the input power supply in real time, facilitating user monitoring of power supply stability. The start / stop unit 17 includes a control panel with start and stop buttons, supporting one-button start / stop operation. After startup, the system enters test mode and self-checks all connections; upon shutdown, the output signal is safely disconnected to prevent residual current from affecting the CT circuit.

[0033] Test cable 4 is a multi-core shielded cable, equipped with a special clamp or plug, for fixing and connecting to the power supply side current transformer unit 5, the circuit breaker bushing current transformer unit 6, and the main transformer bushing current transformer unit 7, respectively. The cable itself is made of high-insulation material, which can ensure interference-free signal transmission and support simultaneous injection of AC current into the primary side of multiple CTs. The wireless phase comparator host 2 is also equipped with an expansion interface and a new wireless phase comparator data plug 22. The data plug 22 can be in the form of USB or a dedicated serial port for physical connection with the host data interface 21 on the AC signal generator 1 to realize wired data backup transmission.

[0034] The wireless phase comparator slave unit 3 supports a multi-unit parallel mode. Each slave unit is connected to the power supply side current transformer unit 5, the circuit breaker bushing current transformer unit 6, and the main transformer bushing current transformer unit 7, respectively, and provides wireless phase detection through built-in sensors. The wireless phase comparator slave unit 3 is equipped with an adjustable bracket for easy fixing near the CT tube to acquire local phase signals.

[0035] The signal conditioning unit 11 of the AC signal generator 1 is internally connected to the generator circuit and is connected to the test cable 4 through the AC signal output unit 12. The test cable 4 is fixedly connected to the power supply side current transformer unit 5, the circuit breaker bushing current transformer unit 6, and the main transformer bushing current transformer unit 7, forming a primary side signal injection path.

[0036] The AC power input unit 13 is electrically connected to the AC power circuit breaker 14, allowing external power to be supplied. The start / stop unit 17 is connected to the generator motherboard via a control line to manage the test conditions. The wireless phase comparator data plug 22 of the wireless phase comparator host 2 interfaces with the host data interface 21 to achieve data synchronization. The wireless phase comparator slave unit 3 is wirelessly connected to each CT unit, transmitting phase data to the host 2 using a 2.4G module.

[0037] When an external power source is connected, the AC power circuit breaker 14 ensures safe power supply, while the power current display unit 15 and the power voltage display unit 16 monitor parameters. After the start / stop unit 17 is activated, the signal conditioning unit 11 optimizes the AC current, which is then injected into the primary side of the CT via the output unit 12 and the test cable 4. The wireless phase comparator slave unit 3 collects phase signals from each CT unit and wirelessly transmits them to the host unit 2. The host unit receives and backs up the generator data via the data connector 22 and performs comprehensive calculations.

[0038] Example 3 Reference Figures 1-3 This embodiment is based on the previous embodiment, and differs from the previous embodiment in that: The inspection and measurement method is based on the calibration system of Examples 1 and 2, focusing on the optimization of the automated testing process, including detailed steps for turns ratio polarity testing, insulation resistance testing, and DC resistance testing. Through preset reference values ​​and real-time comparison, intelligent diagnosis of CT circuit defects is achieved, supporting automatic shutdown and maintenance prompts in case of faults.

[0039] The entire testing and measurement method utilizes the system's hardware infrastructure: an AC signal generator 1, a wireless phase comparator host 2, and a wireless phase comparator slave 3, connected to the CT secondary circuit via wire 8. First, technicians need to ensure that the wireless phase comparator slave 3 and the wireless phase comparator host 2 are properly deployed and that a master-slave communication connection is established. The connection between the wireless phase comparator slave 3 and the wireless phase comparator host 2 can use the 2.4G wireless protocol.

[0040] During system initialization, the wireless phase comparator host 2 loads the CT nameplate parameters, which can be used as a global reference for subsequent operations. The wireless phase comparator host 2 can cover four CT windings at once, making it suitable for 110kV substation renovation and commissioning scenarios, avoiding the inefficiency and errors of traditional multi-person voice communication operations.

[0041] First, the AC signal generator 1 is started to generate a stable AC current, and a 3A AC current is input to the primary side of the CT. The current injection path is through the test cable 4, and connected to the power supply side current transformer unit 5, the circuit breaker bushing current transformer unit 6, and the main transformer bushing current transformer unit 7.

[0042] The wireless phase comparator host 2 can receive and process secondary circuit signals in real time through the wire 8. At the same time, the wireless phase comparator slave 3 monitors the primary side signal to ensure stable injection current.

[0043] In the turns ratio polarity test procedure, a reference turns ratio value needs to be preset first. In this scheme, the reference turns ratio value can be confirmed based on the nameplate parameters of the CT. After inputting a 3A AC current to the primary side, the wireless phase comparator host 2 tests the secondary side current. The data from the primary side and the secondary side are divided to obtain the turns ratio values ​​of the four windings. The entire test generally takes less than 1.5 minutes and supports parallel processing of data from multiple windings.

[0044] The error rate is calculated by comparing the actual transformer ratio with the reference transformer ratio. When the error rate is below 2%, the system operates normally and continues the process; when the error rate is above 2%, the system malfunctions and is shut down for maintenance.

[0045] In the insulation resistance test procedure, a test voltage of 1000V is selected in advance because 1000V voltage conforms to the substation voltage standard. The wireless phase comparator host 2 can test the insulation resistance between the N phase of four windings and the ground wire E at the same time, and the test time is controlled within 90 seconds.

[0046] At this point, the actual resistance value can be determined based on the actual resistance value of the insulation resistance. When the actual resistance value is lower than 1MΩ, the system is determined to be operating normally and can continue the process, and the resistance curve is stored. When the actual resistance value is higher than 1MΩ, the system is determined to be operating faulty, and manual intervention is required to stop the machine for maintenance.

[0047] In the DC resistance test procedure, the N-phase resistance value needs to be reserved as a data reference. Before the test, the wireless phase comparator host 2 first measures the N-phase DC resistance as a benchmark. The wireless phase comparator host 2 tests four windings at a time, compares the measured resistance values ​​of phases A, B, and C with the N-phase resistance value, and compares the resistance between A and B, B and C, and C and A.

[0048] The resistance error values ​​obtained for each phase are summarized. At this point, a resistance error judgment can be made. When the total resistance error is less than 1Ω, the system is considered to be operating normally and the process can continue. If any resistance error is greater than 1Ω, the system is considered to be malfunctioning, and manual intervention is required for maintenance.

[0049] The inspection and measurement method in this embodiment is used for the rapid acceptance of newly built or renovated CT bays. In the commissioning of 110kV lines, it can complete the testing of 8 windings within 3 minutes, which is a huge improvement in efficiency compared to the 2 hours of the traditional method. At the same time, the operation threshold is also reduced, and it can be completed by one person, reducing manpower consumption.

[0050] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A secondary circuit acceptance and verification system, characterized in that: include, AC signal generator (1), wireless phase comparator host (2) and wireless phase comparator slave (3); The AC signal generator (1) includes an AC signal conditioning unit (11) and an AC signal output unit (12), which provides signal transmission testing and inputs AC current to the primary side of the current transformer under test; The wireless phase comparator host (2) receives the verification data of the AC signal generator (1) through the host data interface (21) on the AC signal generator (1) and performs sampling calculation through the built-in CPU; The wireless phase comparator slave (3) and the wireless phase comparator host (2) are connected by wireless communication to realize phase detection and data transmission.

2. The secondary circuit acceptance and verification system according to claim 1, characterized in that: An AC signal generator (1) is connected to a signal conditioning unit (11) and a test cable (4) is connected through an AC signal output unit (12). The test cable (4) is fixedly connected to the power supply side current transformer unit (5), the circuit breaker bushing current transformer unit (6), and the main transformer bushing current transformer unit (7), and inputs AC current to the primary side of the current transformer under test.

3. The secondary circuit acceptance and verification system according to claim 1, characterized in that: The AC signal generator (1) is equipped with an AC power input unit (13), an AC power circuit breaker (14), a power current display unit (15), a power voltage display unit (16), and a start / stop unit (17). The AC power input unit (13) is electrically connected to the AC power circuit breaker (14) for external power supply. The start / stop unit (17) controls the test conditions of the AC signal generator (1).

4. The secondary circuit acceptance and verification system according to any one of claims 1 to 3, characterized in that: The wireless phase comparator host (2) also includes a wireless phase comparator data plug (22) for connecting to the host data interface (21) on the AC signal generator (1). The wireless phase comparator slave unit (3) is connected to the power supply side current transformer unit (5), the circuit breaker bushing current transformer unit (6) and the main transformer bushing current transformer unit (7) respectively to provide wireless phase detection.

5. A testing and measurement method, characterized in that: Including the secondary circuit acceptance and verification system as described in claim 4, and, The wire (8) is connected to the secondary circuit of the current transformer. The wireless phase comparator slave (3) and the wireless phase comparator host (2) are installed and a master-slave communication connection is established. Start the AC signal generator (1) and input AC current to the primary side. The wireless phase comparator host (2) receives the secondary circuit signal and performs internal calculations. The wireless phase comparator slave unit (3) stores the test results for insulation resistance, DC resistance and turns ratio polarity tests. The wireless phase comparator host unit (2) analyzes all test data and judges the correctness of the circuit by comparing it with the nameplate parameters.

6. The secondary circuit acceptance and verification system according to claim 5, characterized in that: In the polarity change test procedure, Preset reference ratio value; After inputting a 3A AC current to the primary side, the wireless phase comparator host (2) tests the secondary side current to obtain the actual turns ratio of the four windings. The test duration is 1.5 minutes. The error rate is obtained by comparing the actual ratio value with the reference ratio value, and the error rate is determined. When the error rate is below 2%, the system operates normally and continues the process; When the error rate is higher than 2%, the system malfunctions and needs to be shut down for maintenance.

7. The secondary circuit acceptance and verification system according to claim 5, characterized in that: In the insulation resistance test procedure, Pre-select a test voltage of 1000V, and the wireless phase comparator host (2) tests the insulation resistance between the N phase of the four windings and the ground wire E at one time; The actual resistance value is determined based on the actual resistance value of the insulation resistance. When the actual resistance is less than 1mΩ, the system operates normally and continues the process. When the actual resistance is higher than 1mΩ, the system malfunctions and needs to be shut down for maintenance.

8. The secondary circuit acceptance and verification system according to claim 6 or 7, characterized in that: In the DC resistance test procedure, Reserve the N-phase resistance value as a data reference; The wireless phase comparator host (2) tests four windings at a time, compares the measured resistance values ​​of phases A, B, and C with the resistance value of phase N, and compares the resistance between A and B, B and C, and C and A. Summarize the resistance value errors obtained for each phase and determine the resistance error. When the total resistance error is less than 1 ohm, the system operates normally and continues the process; If any resistance error exceeds 1 ohm, the system malfunctions and must be shut down for maintenance.

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