CN116125360A - Intelligent current collector based on wireless transmission - Google Patents

Abstract

The invention relates to the technical field of power systems, in particular to an intelligent current transformer based on wireless transmission, which comprises a large current generator, a sampling module, a first wireless communication module, a comprehensive processing module, an intelligent clamp meter and a second wireless communication module, wherein the large current generator is positioned at a primary equipment site of a current transformer; according to the intelligent current transformer based on wireless transmission, the current is applied to the primary side of the CT through the large current generator, the sampling module is used for sampling the first current signal or/and the voltage signal, and the first current signal or/and the voltage signal is compared with the second current signal acquired by the intelligent clamp meter to finish the test, so that the transformation ratio in a tested current transformer loop can be automatically judged, and the problem of abnormal polarity of the CT is found.

Description

Intelligent current collector based on wireless transmission

Technical Field

The invention relates to the technical field of power systems, in particular to an intelligent current collector based on wireless transmission.

Background

Current Transformers (CTs) are important electrical devices in electrical power systems that take on the role of isolation between high and low voltage systems and conversion of high voltage quantities to low voltage quantities. The wiring is correct or not, and has important significance for the normal operation of equipment such as protection, measurement, metering and the like of the system. When a CT is newly installed, and a CT secondary cable is put into operation or replaced, the accuracy of the polarity of the CT is measured, and the method is an indispensable working procedure for relay protection staff.

The polarity of a current transformer refers to the relationship of the current direction between the primary winding and the secondary winding of the current transformer. According to the rule, the head end of the CT primary winding is marked as P1, and the tail end is marked as P2; the head end of the secondary winding is denoted as S1 and the tail end is denoted as S2. In the wiring, P1 and S1, P2 and S2 are called homopolar ends. When the current I1 of the primary winding flows from the leading end P1 and flows from the trailing end P2, the current I2 induced in the secondary winding flows from the leading end S1 and flows from the trailing end S2, and the directions of magnetic fluxes generated in the core are the same, and such a CT polarity flag is called a polarity reduction. Otherwise, it is called adding polarity. The common current transformers all adopt polarity reduction except special regulations.

The current transformer must be subjected to polarity measurements before and after handover and overhaul. In addition, the polarity check of CT is also performed when the differential protection, power direction protection is false or the meter is reversed in operation, because if the current transformer is misconnected in polarity, the following hazard will occur:

1. if the current transformer is used in a relay protection circuit, misoperation or refusal of the relay protection device can be caused, meanwhile, operation monitoring and accident handling of a power system can be influenced, and equipment and personal safety can be endangered when serious.

2. Current transformers, as used in meter metering loops, can cause incorrect metering of various instruments, indications of meters, and electrical energy.

3. If any one phase is reversed in polarity, the current of one phase (generally the middle phase) of the unconnected current transformer is increased by 2 times compared with the current of other phases.

4. The current transformer with incomplete star connection is adopted, for example, two phases are connected reversely, and the phase angle difference between the current transformer and the corresponding primary current is 180 degrees although the three-phase current of the secondary measurement is balanced, so that the kilowatt-hour meter is reversed.

The traditional polarity detection method includes a direct current method and an alternating current method.

For the polarity measurement of a single-phase voltage or current transformer, the direct current method has the advantages of simple principle, simple and convenient wiring of measuring equipment, uncomplicated operation and the like, and is suitable for the detection and judgment of the polarity of the single transformer. For multiple polarity measurement, the direct current method needs frequent plug experiment wiring, needs cooperation of multiple persons, is time-consuming and labor-consuming, and has potential safety hazard, so that the direct current method is not suitable for polarity measurement of multiple transformers.

The advantage of the current method is that the actual operation of the current transformer is basically simulated (only the difference in the magnitude of the secondary load). But as the system capacity increases, the current transformer current becomes larger, up to tens of thousands of amperes. Applying current to hundreds of amperes in the field has been difficult, and thousands or tens of thousands of amperes are almost impossible. Reducing some test currents has little meaning to reduce test capacity, and reducing too much increases the error of the current transformer.

Taking a secondary system of a transformer substation or a power plant as an example, a CT loop is complex, and the problems of incorrect selection of CT transformation ratio, opposite CT polarity and the like frequently occur in experiments, so that misoperation or other injuries of a protection device are caused. Therefore, no matter the direct current method and the alternating current method often need a plurality of test results to mutually prove so as to obtain a correct conclusion, the test process is complex and complicated, and the accuracy of the test results is not high.

Disclosure of Invention

The embodiment of the invention provides an intelligent current collector based on wireless transmission, which has high detection efficiency, simple and convenient operation and high safety.

The invention provides an intelligent current collector based on wireless transmission, which comprises: the intelligent clamp meter comprises a large current generator, a sampling module, a first wireless communication module, a comprehensive processing module, an intelligent clamp meter and a second wireless communication module, wherein the large current generator, the sampling module, the first wireless communication module and the comprehensive processing module are positioned on a primary equipment site of a current transformer;

the high-current generator is used for applying current to the primary side of the current transformer;

the sampling module is used for collecting a first current signal or/and a voltage signal of the primary side of the current transformer and sending the first current signal or/and the voltage signal to the comprehensive processing module;

the intelligent clamp meter is used for collecting a second current signal of the secondary side of the current transformer;

the first wireless communication module is connected with the comprehensive processing module, the second wireless communication module is connected with the intelligent clamp meter, and the first wireless communication module and the second wireless communication module establish a wireless communication link and are used for transmitting a second current signal acquired by the intelligent clamp meter to the comprehensive processing module sequentially through the second wireless communication module and the first wireless communication module;

the comprehensive processing module is used for obtaining the transformation ratio and the polarity of the current transformer according to the received first current signal or/and voltage signal and the received second current signal and judging the correctness of the current transformer.

Further, the method may further include: and the waveform display module is connected with the comprehensive processing module and is used for displaying the waveform of the first current signal and the waveform of the second current signal.

Furthermore, the integrated processing module can also comprise a CPU, and a wireless communication interface, a wired communication interface, an SD memory unit and a DDR memory which are respectively connected with the CPU.

Further, the secondary current signal includes the magnitude and phase of the current,

the comprehensive processing module judges the transformation ratio of the current transformer and can be obtained by comparing the amplitude of the first current signal acquired by the sampling module with the amplitude of the second current signal acquired by the intelligent clamp meter.

The comprehensive processing module judges the polarity of the current transformer, and can be based on the phase difference between the first current signal or the first voltage signal and the second current signal, and when the phase difference is in a set interval, the polarity is reduced, and otherwise the polarity is increased.

Further, the phase difference between the first current signal or the first voltage signal and the second current signal may specifically be that the first current signal or the first voltage signal and the second current signal are subjected to exclusive or processing to obtain a square wave signal, the duty ratio of the square wave signal is measured, and the duty ratio is multiplied by 180 ° to obtain the value of the phase difference.

Furthermore, the comprehensive processing module can time the second current signal sent by the intelligent clamp meter before judging the polarity of the current transformer, and the influence of the transmission delay time in the message transmission process between the first wireless communication module and the second wireless communication module is reduced.

Further, the transmission delay time may be obtained based on a Hankel matrix and singular value decomposition, and specifically includes:

constructing a Hankel matrix of the actual transmission delay time of the second current signal;

SVD (singular value decomposition) is carried out on the constructed Hankel matrix to obtain singular values of the Hankel matrix after decomposition;

reconstructing the signals with the first m larger singular values, and then summing and averaging elements on the inverse diagonal of the reconstructed matrix to be used as the estimated value of the transmission delay time.

According to the intelligent current transformer based on wireless transmission, the current is applied to the primary side of the CT through the large current generator, the first current signal or/and the voltage signal are sampled through the sampling module, and the first current signal or/and the voltage signal are compared with the second current signal of the intelligent clamp meter transmitted by the wireless communication module to finish the test, so that the transformation ratio in a tested current transformer loop can be automatically judged, and the problems of abnormal CT polarity and the like are found. In the polarity detection of the connection of a group of three-phase voltage or current transformers on site, the method has the advantages of less measurement times, high measurement accuracy, simple and visual judgment basis, convenient operation, capability of displaying the polarity and the transformation ratio simultaneously, capability of greatly improving the efficiency of detection work and higher-level polarity detection method. The method overcomes the problems that the primary loop or the secondary loop needs to be frequently changed in the original testing process, and the time and the labor are wasted and the potential safety hazard is caused by using a long cable.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments of the present invention will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a functional block diagram of a preferred embodiment of the present invention;

FIG. 2 is an internal schematic diagram of the integrated processing module of FIG. 1;

FIG. 3 is a schematic diagram of the transmission delay according to an embodiment of the present invention;

fig. 4 is a schematic diagram showing the phase difference obtained in the present embodiment.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The intelligent current collector is used for secondary CT detection of power equipment such as transformer substations, power plants, industrial and mining enterprises and the like, is used for CT transformation ratio measurement and CT polarity measurement, and can rapidly judge the correctness of CT transformation ratio and CT polarity.

The embodiment is an intelligent current collector based on wireless transmission. The system comprises a heavy current generator, a sampling module, a waveform display module, a first wireless communication module, a comprehensive processing module, an intelligent clamp meter and a second wireless communication module, wherein the heavy current generator, the sampling module, the waveform display module, the first wireless communication module and the comprehensive processing module are positioned on a primary equipment site;

the high-current generator is used for applying current to the primary side of the current transformer;

the sampling module is used for collecting a first current signal or/and a voltage signal of the primary side of the current transformer and sending the first current signal or/and the voltage signal to the comprehensive processing module;

the intelligent clamp meter is used for collecting a second current signal of the secondary side of the current transformer;

the first wireless communication module is connected with the comprehensive processing module, the second wireless communication module is connected with the intelligent clamp meter, and the first wireless communication module and the second wireless communication module establish a wireless communication link and are used for transmitting a second current signal acquired by the intelligent clamp meter to the comprehensive processing module sequentially through the second wireless communication module and the first wireless communication module;

and the comprehensive processing module is used for carrying out transformation ratio calculation and polarity measurement according to the received first current signal and the received second current signal.

The waveform display module is connected with the comprehensive processing module and is used for displaying the waveform of the first current signal and the waveform of the second current signal, and the waveform display module can also be used as a man-machine interaction interface.

Based on the structure, the current is applied to the primary side through the large current generator, then the secondary current is measured through the intelligent clamp meter, the amplitude and the phase of the secondary current are obtained, and the correctness of the tested current transformer loop is judged by comparing the measured current with the applied current.

The high-current generator adopts an imported high-permeability magnetic material, has the characteristics of small volume, strong electric power resistance and convenient use, and is suitable for current load tests and temperature rise tests of frequency 50HZ switches, current transformers and other electrical equipment. Maximum output current 1000A, single phase can stably output maximum current more than 1 hour. After the high-current generator is connected with a working power supply, the high-current required by the test is obtained by adjusting the output voltage of the voltage regulator.

FIG. 2 is an internal schematic diagram of the integrated processing module in FIG. 1, where the integrated processing module includes a CPU that uses an I5 kernel processor, and a human-machine interface, 433 wireless communication interface, RS485 wired communication interface, 4G SD memory unit, and 128G DDR memory that are respectively connected with the CPU. The comprehensive processing module is provided with a 232/485 communication circuit through the wired communication interface, and is in wired real-time communication with the sampling module to perform data transmission, and receives and synchronously processes the electric quantity information data of the high-current generator. The first wireless communication module and the second wireless communication module adopt 433M wireless communication modules, so that the comprehensive processing module and the intelligent clamp meter communicate in real time in a wireless mode, data transmission is carried out, and current information data of the secondary circuit are received and synchronously processed.

The comprehensive processing module is also connected with a waveform display module, and a liquid crystal display panel is used as a human-computer interface, so that the primary loop voltage and current waveform and the secondary loop current waveform can be displayed in real time, the primary voltage and current signals received in real time are compared with the secondary current signals, and further information such as transformation ratio calculation, polarity measurement, polarity discrimination, transformation ratio, loop integrity and the like is carried out. The RS485 wired communication module is used for linking the sampling module and collecting current and voltage waveforms of the primary side. 433M wireless communication module is used for intelligent clamp meter's link, gathers the wave form of secondary side current.

The CPU of the sampling module adopts a MM32F3277G9P type chip, and the chip is based on a 32-bit microcontroller product developed by an ARM-Cortex-M3 processor, and has the characteristics of high performance and low power consumption. The sampling module can be used for measuring the magnitude and waveform of the primary loop current of the current transformer according to the parameters of the heavy current generator and matching with corresponding PT\CT (closed CT can be adopted), and the measuring range is as follows: 0-1000A, realizing acquisition of voltage and current information data of a single-phase or three-phase circuit; the peripheral circuit set AD circuit is provided, so that the primary loop circuit current information data of the current transformer can be reliably and accurately measured and recorded, and the primary current information data comprises primary current quantity and primary waveform (sine wave); the primary loop open function can be judged, so that overvoltage at two ends can not occur when the primary loop is open; the sampling module is also provided with a 232/485 communication circuit, and can communicate with the comprehensive processing module in real time to transmit relevant data such as voltage and current.

Specifically, the intelligent clamp meter comprises two parts: current information acquisition device and pincerlike CT.

The clamp-on CT is used for measuring the secondary circuit current information data of the measured current transformer, and the measuring range is as follows: 0 to 20A. The CPU of the current information acquisition device adopts a MM32F3277G9P type chip, and the chip is based on a 32-bit microcontroller product developed by an ARM-Cortex-M3 processor, and has the characteristics of high performance and low power consumption; the peripheral circuit set AD is provided with a circuit, so that the secondary circuit current information data of the current transformer can be reliably and accurately measured; the corresponding CT is provided, and secondary current information data of a plurality of current transformer windings can be measured simultaneously or respectively.

The first wireless communication module and the second wireless communication module adopt 433M wireless communication modules, the working frequency of the data transmitting module is 315M, the SAW frequency stabilization is adopted, the frequency stability is extremely high, and when the environmental temperature changes between minus 25 degrees and plus 85 degrees, the frequency drift is only 3 ppm/degree. The 433M wireless communication module can transmit secondary loop current information data to the comprehensive processing module in real time through a wireless communication technology; the 433M wireless module is particularly suitable for a multiple-input-multiple-output wireless remote control and data transmission system. The frequency stability of the acoustic surface resonator is inferior to that of a crystal, but the frequency stability and consistency of a common LC oscillator are poor, and even if a high-quality trimming capacitor is adopted, the temperature difference change and vibration can hardly ensure that the tuned frequency point cannot deviate.

In actual use, the first wireless communication module and the second wireless communication module can be respectively embedded into the comprehensive processing module and the intelligent clamp meter. And setting a first wireless communication module in the comprehensive processing module as a host, and setting a second wireless communication module of the intelligent clamp meter as a slave. The slaves are distributed on each working point and are responsible for collecting intelligent pincerlike presentation field data, sending the collected data to the host computer through the low-power-consumption long-distance wireless data transmission module, and receiving control commands sent by the host computer. The host computer is responsible for sending control commands to control the slave computers to work, receiving data sent by the slave computers, and storing, analyzing and calculating the data. When the slave module is in the low power consumption mode, the host is always in an active state, the slave is always in the low power consumption state when no event occurs, the current event is processed when the event occurs, and the slave returns to the low power consumption state after the processing is completed.

Based on the above structure, the measurement method of the present embodiment is as follows:

(1) The high-current generator is arranged on a primary equipment site and used for generating high-current output and applying the high-current output to a primary side loop of the current transformer to be tested.

(2) Ensuring reliable grounding of the high current generator and the device under test.

(3) The intelligent current collector is correctly connected with the tested loop, the side close to the bus is selected as a current application point, and the current input end of the intelligent current collector is connected; the measured loop is dosed. The position of the large-scale switch is selected according to the magnitude of the output current. The measured loop transformation ratio is 2000:1, the current amplitude is set to 200A, and the phase between the first voltage signal and the first current signal is 0 degrees (the test loop has no capacitive or inductive element).

(4) The voltage stabilizer of the high-current generator is reset to zero, and then a start test button is pressed. At this time, the handle of the voltage stabilizer is held clockwise, the hand wheel of the voltage stabilizer is gradually rotated, and the current value of the sampling module is stared at until the required current value is reached.

(5) The intelligent clamp meter is positioned on a secondary equipment site and is used for measuring secondary current phasors.

(6) The comprehensive processing module collects the current and voltage values of the sampling module.

(7) The secondary current value sampled by the intelligent clamp meter is transmitted to the comprehensive processing unit through the wireless communication module

(8) The comprehensive processing module forms waveform data of the current transformer to be tested according to the collected current-voltage vector data and the amplitude and the polarity of the secondary side current of the current transformer to be tested, and automatically judges the correctness of the current transformer loop.

The secondary current signal comprises the amplitude and the phase of current, the comprehensive processing module judges the transformation ratio of the current transformer, and the actual correct CT transformation ratio can be obtained by comparing the amplitude of the first current signal acquired by the sampling module with the amplitude of the second current signal acquired by the intelligent clamp meter.

The polarity judgment of the current transformer is obtained through the phase difference between the measured current and the voltage, namely the phase difference between the second current signal and the first voltage signal, and when the phase difference is in a set interval (for example, 90-270 degrees), the polarity is reduced, and otherwise, the polarity is increased.

The voltage waveform is u (t) =usin (ωt+ψ) ₁ )

The current waveform is i (t) isin (ωt+ψ) ₂ )

The phase difference is ψ (t) =ωt+ψ ₁ -ψ ₂

From the above formula, it can be seen that the phase difference is a linear function of time t.

The judgment result obtained by the comprehensive processing module is exemplified as follows:

a. and judging that the current phase of the current transformer to be tested is 180 degrees and the polarity of the current transformer is opposite, namely the polarity is reduced.

b. And judging that the current transformer transformation ratio is wrong when the current amplitude of the tested current transformer is 20 mA.

Only two sets of error data are listed for illustration, and the remainder will not be described in detail.

And the comprehensive processing module is used for comparing the second current signal sent by the intelligent clamp meter before judging the polarity of the current transformer. The invention adopts a mode of combining the time synchronization technology based on the power system with the zero crossing point phase measurement method to realize phase measurement, uses the synchronous time synchronization signal to respectively time the intelligent clamp meter and the current collector, samples current and voltage under the time keeping effect of the constant temperature crystal oscillator, and compares phases through the zero crossing point moment value.

The clock synchronization technology of the power system is based on the fact that message transmission paths and delays of the master equipment and the slave equipment are the same. In practical network applications, the same network information transmission delay only occurs under the conditions of unobstructed network and less traffic. In the practical application scenario of the power system, the time synchronization network is not only used for transmitting time information, but also substation working condition information, fault information and the like. The total message types are numerous, the flow is variable, and the requirement for symmetrical transmission of time messages is not necessarily met at all times. In the invention, the comprehensive processing module and the intelligent clamp meter perform information interaction in a wireless communication mode. In a wireless network system, network communication data often causes phenomena such as collision and congestion due to bandwidth, changed channels and external interference, so that information interaction delay can be caused.

As shown in fig. 3, for the schematic diagram when the transmission Delay occurs, it is assumed that the master clock device encounters network congestion during the sending process of the time-to-time message, and the time to reach the slave clock device is delayed from the expected time, and the network congestion during the sending process of the delay_req message is improved.

At t ^* As the actual delay time of the message in the time setting process, t is the ideal delay time, delta t is the time of the Sync message which is delayed than the expected time, t _sm For the time delay of a master link and a slave link, t _ms For the main link delay, then 2 ^* ＝t _sm +t _ms +Δt

And t _sm ＝t _ms

Deriving t ^* ＝t+Δt/2

As can be seen from the above equation, in the case of network congestion, there is an uncertainty Δt/2 between the actual transmission delay time and the theoretical delay time. If an extreme network congestion occurs at this time, the value of Δt will approach infinity, which brings great deterioration to the time synchronization of the master and slave devices, possibly resulting in the loss of synchronization of the slave clocks and free oscillation.

In order to improve the time setting precision, the method adapts to the asymmetric environment of a link and reduces the influence of the transmission delay time in the message transmission process between the first wireless communication module and the second wireless communication module. The invention provides a method for processing interference caused by wireless network delay and environmental influence based on Hankel matrix and singular value decomposition, and delay instability caused by the fact that the actual transmission distance is generally within 200m can be effectively removed, so that the influence of network delay is reduced to the minimum, and the accuracy of the whole system is possible to achieve sub-microsecond. The method comprises the following steps:

(1) A Hankel matrix H is constructed.

For a measured signal y (t) =s (t) +c (t), t=1, 2,3 …, N, where s (t) is the useful signal and c (t) is the noise signal. A Hankel matrix can be constructed from which the elements on each diagonal of the matrix are identical, and each row or column of H can be cyclically shifted to obtain the original one-dimensional signal t.

(2) And carrying out SVD decomposition on the constructed matrix.

Wherein σ= [ σ ] ₁ σ ₂ …σ _n ]Is N singular values of the matrix and satisfies sigma ₁ ＞σ ₂ ＞σ _n

H can be written as

Since the measured source signal is composed of both the desired signal and the noise signal, the matrix is also a pointer composed of both the desired signal and the noise signal. The singular values of the matrix may reflect the condition of signal and noise signal energy concentration. The larger singular value will reflect mainly useful signals, the smaller singular value will reflect mainly noise signals, and the noise in the signals can be removed by zeroing out the singular value that reflects the noise in this part.

(3) And then carrying out weighted average on the elements in the matrix to obtain the noise-reduced signal channel. And selecting a larger signal to reconstruct the signal. Reconstructed signal

Where m represents the singular value cut-off position,

representing the filtered m-th order reconstructed matrix, wherein randomly generated noise has been removed, and reconstructing the reconstructed matrix +.>

And summing the average values of the elements on the opposite diagonals to obtain the estimated value of the signal.

So far, after the link delay of the master clock and the link delay of the slave clock are respectively processed by utilizing the Hankel matrix and the singular value decomposition, the original correction formula is replaced by the statistical mean value, so that the interference of congestion and queue delay of normal distribution (the environment with the same mean value of the master clock and the slave clock) can be effectively reduced, and a relatively accurate delay delta t is obtained. In most cases, it is easy to find that the singular value σ decreases particularly fast when we arrange the singular values in the matrix Σ in order from large to small. Most often, the sum of the first 10% singular values accounts for more than 99% of the total singular value sum. In other words, most singular values are small and basically not useful, so we can approximate this matrix with the first m singular values (where m can be reasonably chosen according to practice), which is also the greatest advantage of the present embodiment in selecting the algorithm.

(4) And performing exclusive OR processing on the first voltage signal and the second current signal according to the transmission delay delta t, outputting a square wave signal, and measuring the duty ratio of the square wave signal, wherein the phase difference is the duty ratio multiplied by 180 degrees.

As shown in fig. 4, which is a schematic diagram of the phase difference obtained in the present embodiment, according to ψ (t) =ω (t- Δt) +ψ ₁ -ψ ₂ And subtracting the transmission delay time delta t, taking square waves of the first voltage signal and the second current signal waveform based on the first voltage signal and the second current signal waveform, and performing exclusive or to obtain a phase difference.

Since the phase angle between the first voltage signal and the first current signal in the primary loop is 0 or a fixed value, the first current signal and the second current signal may be exclusive-ored in the above (4), and the phase difference can be obtained as well.

The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.

Claims (7)

1. An intelligent current collector based on wireless transmission, which is characterized by comprising: the intelligent clamp meter comprises a large current generator, a sampling module, a first wireless communication module, a comprehensive processing module, an intelligent clamp meter and a second wireless communication module, wherein the large current generator, the sampling module, the first wireless communication module and the comprehensive processing module are positioned on a primary equipment site of a current transformer;

the high-current generator is used for applying current to the primary side of the current transformer;

the sampling module is used for collecting a first current signal or/and a voltage signal of the primary side of the current transformer and sending the first current signal or/and the voltage signal to the comprehensive processing module;

the intelligent clamp meter is used for collecting a second current signal of the secondary side of the current transformer;

the first wireless communication module is connected with the comprehensive processing module, the second wireless communication module is connected with the intelligent clamp meter, and the first wireless communication module and the second wireless communication module establish a wireless communication link and are used for transmitting a second current signal acquired by the intelligent clamp meter to the comprehensive processing module sequentially through the second wireless communication module and the first wireless communication module;

the comprehensive processing module is used for obtaining the transformation ratio and the polarity of the current transformer according to the received first current signal or/and voltage signal and the received second current signal and judging the correctness of the current transformer.

2. The wireless transmission-based intelligent current transformer of claim 1, further comprising: and the waveform display module is connected with the comprehensive processing module and is used for displaying the waveform of the first current signal and the waveform of the second current signal.

3. The intelligent current collector based on wireless transmission according to claim 2, wherein the integrated processing module further comprises a CPU, and a wireless communication interface, a wired communication interface, an SD memory unit and a DDR memory which are respectively connected with the CPU.

4. The wireless transmission-based intelligent current transformer of claim 1,2 or 3, wherein the secondary current signal comprises a magnitude and a phase of a current,

the comprehensive processing module judges the transformation ratio of the current transformer, and the transformation ratio is obtained by comparing the amplitude of the first current signal acquired by the sampling module with the amplitude of the second current signal acquired by the intelligent clamp meter.

The comprehensive processing module judges the polarity of the current transformer based on the phase difference between the first current signal or the first voltage signal and the second current signal, and when the phase difference is in a set interval, the polarity is reduced, and otherwise the polarity is increased.

5. The intelligent current transformer based on wireless transmission according to claim 4, wherein the phase difference between the first current signal or the first voltage signal and the second current signal is specifically obtained by performing exclusive-or processing on the first current signal or the first voltage signal and the second current signal to obtain a square wave signal, measuring the duty ratio of the square wave signal, and obtaining the value of the phase difference by multiplying the duty ratio by 180 °.

6. The intelligent current transformer based on wireless transmission according to claim 5, wherein the integrated processing module performs time synchronization on the second current signal sent by the intelligent clamp meter before judging the polarity of the current transformer, so as to reduce the influence of the transmission delay time in the message transmission process between the first wireless communication module and the second wireless communication module.

7. The intelligent current collector based on wireless transmission according to claim 6, wherein the transmission delay time is obtained based on Hankel matrix and singular value decomposition, and specifically comprises:

constructing a Hankel matrix of the actual transmission delay time of the second current signal;

SVD (singular value decomposition) is carried out on the constructed Hankel matrix to obtain singular values of the Hankel matrix after decomposition;

reconstructing the signals with the first m larger singular values, and then summing and averaging elements on the inverse diagonal of the reconstructed matrix to be used as the estimated value of the transmission delay time.

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