A through-core current transformer disconnection and polarity inspection system and control method thereof

Abstract

The present invention discloses a through-core current transformer disconnection and polarity inspection system and a control method thereof, which comprises a plurality of controllable pulse generating circuits, a plurality of Hall sensors, and the secondary output terminal of the through-core current transformer CT positively penetrates the Hall sensor; a multi-way switching switch selection circuit SWA, SWB, SWC, SWA, SWB respectively control the frequency and amplitude of the output pulses of all controllable pulse generating circuits, and SWC is responsible for selecting one of the Hall sensor outputs; a switching control circuit controls the selection of one of the controllable pulse generating circuits to output pulses; a frequency control circuit and an amplitude control circuit respectively control the frequency and amplitude of the output pulses, and shape them; a data acquisition conversion circuit, which is connected to the multi-way switching switch selection circuit and is responsible for the signal processing and acquisition of the sampling pulses; and a core control module. The present invention can realize disconnection detection and polarity detection of multiple through-core current transformers without affecting the normal monitoring of the through-core current transformer, and has high detection efficiency and high precision.

Description

[Technical field]

[0001] The invention belongs to the technical field of electric power systems, and in particular relates to a through-core current transformer disconnection and polarity inspection system and a control method thereof. [Background technology]

[0002] In the power system, through-type current transformers (CT) are widely used, such as detecting the zero-sequence current of the power system, the leakage current of the equipment, and the unbalanced current. In the above application, under the normal operation of the primary equipment, the primary current synthetic magnetic flux of the through-type current is zero, so the secondary current is also zero. The through-type CT will only have output current when the primary equipment fails. When the through-type CT has a secondary wire break or a wire break inside the coil due to some reasons, the secondary current is also zero, so it cannot be distinguished from the normal operation of the equipment. Therefore, the wire break detection of the through-type CT is more difficult; at the same time, since the through-type CT has no current under normal circumstances, if the CT polarity (same-name terminal) is connected incorrectly, it will cause some application errors (such as zero-sequence current direction determination in relay protection). Therefore, the polarity detection of the through-type CT is also particularly important.

[0003] In the prior art, the disconnection detection and polarity detection of through-core CT are detected by manual detection, such as Figure 1 As shown in the figure, when the primary circuit of the CT is powered off, an alternating current is applied to the primary circuit through a current source, and an ammeter is inserted into the secondary circuit to detect the presence or absence of current to determine whether the through-core CT is broken; Figure 2 As shown, a battery (or DC power supply) is used to shock the primary circuit to generate pulses, and a DC pendulum voltmeter is connected to the secondary circuit to determine the polarity (same-name end) by the direction of the pendulum. Manual detection is inefficient and labor-intensive, and it is also unable to detect CT disconnection and polarity anomalies when the primary equipment is working.

[0004] In the prior art, there is also an online detection method, such as Figure 3 As shown, high-order harmonics are applied to the through-type CT by winding the coil, and the secondary circuit is detected to determine whether the through-type CT is broken. The high-order harmonics are generated by the transformer open circuit judgment device and applied to the CT coil, and then the harmonic current in the current transformer is detected to determine whether the CT is open. Although this method adopts an online method, harmonics will interfere with other secondary equipment. At the same time, due to different parameters of different CTs, multi-CT inspection cannot be realized. Only one CT can be equipped with an open circuit monitoring device, which is costly and inefficient.

[0005] Therefore, it is necessary to provide a new through-core current transformer disconnection and polarity inspection system and control method thereof to solve the above problems. [Summary of the invention]

[0006] The main purpose of the present invention is to provide a through-core current transformer disconnection and polarity inspection system, which can realize disconnection detection and polarity detection of multiple through-core current transformers without affecting the normal monitoring of the through-core current transformers, with high detection efficiency and high accuracy.

[0007] The present invention achieves the above-mentioned purpose through the following technical scheme: a through-core current transformer disconnection and polarity inspection system, which comprises

[0008] A number of controllable pulse generating circuits KCP, whose pulses are output to the primary side of the through-core current transformer CT;

[0009] A number of Hall sensors HR, responsible for pulse collection and measurement, the number of which is the same as the controllable pulse generating circuit KCP, and the secondary output terminal of the through-core current transformer CT is forwardly penetrated into the Hall sensor HR;

[0010] Multi-way switch selection circuits SWA, SWB, SWC, wherein SWA controls the frequency of the output pulses of all controllable pulse generating circuits KCP, SWB controls the amplitude of the output pulses of all controllable pulse generating circuits KCP, and SWC is responsible for selecting the output of a corresponding Hall sensor HR;

[0011] The switching control circuit SWMD controls and selects one of the controllable pulse generating circuits KCP to output a pulse;

[0012] The frequency control circuit FCMD and the amplitude control circuit VCMD respectively control the frequency and amplitude of the output pulse and shape it;

[0013] The data acquisition conversion circuit ADIMD is connected to the multi-way switch selection circuit SWC and is responsible for signal processing and acquisition of the acquisition pulses; and

[0014] The core control module is electrically connected to the switching control circuit SWMD, the frequency control circuit FCMD, the amplitude control circuit VCMD and the data acquisition conversion circuit ADIMD.

[0015] Furthermore, the data acquisition conversion circuit ADIMD internally includes a low-pass filter, an anti-interference circuit and an ADC acquisition circuit.

[0016] Furthermore, it also includes a power supply for supplying power to the core control module and a human-computer interaction system communicating with the core control module.

[0017] Furthermore, the core control module is in communication with an external power monitoring system.

[0018] Furthermore, the pulse output terminal of the controllable pulse generating circuit KCP passes through the primary side aperture of the through-core current transformer through a wire, and the incoming direction is the same as the specified direction of the current of the primary current carrier.

[0019] Furthermore, the lead wire of the secondary output terminal P1 of the through-core current transformer CT is forwardly inserted into the current Hall sensor, and the outgoing wire is connected to the load and then connected to the secondary output terminal P2 of the through-core current transformer CT.

[0020] Another object of the present invention is to provide a control method for a through-current transformer disconnection and polarity inspection system, which comprises

[0021] S1) The main program starts;

[0022] S2) parameter and system initialization;

[0023] S3) Read the number N of patrol CTs and set the patrol number i=1;

[0024] S4) Execute the circuit breaker inspection logic of CTi;

[0025] S5) Execute polarity inspection logic of CTi;

[0026] S6) Let i=i+1, determine whether i is greater than N, if it is, execute the subsequent code and logic, and then return to step S3), if not, return to step S4).

[0027] Furthermore, the circuit breaker inspection logic in step S4) includes: firstly determining whether the fundamental current IVi0 of the through-core current transformer CT is greater than the CT no-current threshold value, if so, exiting the circuit breaker inspection logic, otherwise performing a circuit breaker detection; allowing the CT to perform an adaptive learning logic to obtain pulse output parameters CT[i][0], CT[i][1] and CT[i][2]; controlling the output amplitude of the controllable pulse generating circuit KCP according to the parameter CT[i][1], and controlling the output frequency of the controllable pulse generating circuit KCP according to the parameter CT[i][2] to control the output pulse, and at the same time detecting the output value IVi1 of the Hall sensor HR; if IVi1 is greater than the set ratio of the adaptively learned pulse recovery value CT[i][0], it is considered that the CT circuit is intact and there is no circuit breaker, otherwise it is determined that the CT circuit is broken, and a CT circuit breaker alarm is issued.

[0028] Furthermore, the polarity inspection logic in step S5) includes: first, determining whether the fundamental current IVi0 of the CT is greater than the CT no-current threshold, if so, directly exiting the polarity detection logic, otherwise, determining whether the CT detects a broken line, if detected, directly exiting the polarity detection logic; otherwise, performing polarity detection, comparing the same-sign and different-sign widths of the control output pulse IVout and the recovery input pulse Ivi, if the same-sign width TD1 is greater than the different-sign width TD2, and TD1 is greater than the set ratio of the output period Tout of the control output pulse IVout, it is considered that the CT polarity connection is correct, otherwise it is determined that the polarity is reversed.

[0029] Furthermore, the adaptive learning includes: under a given initial value, first changing the Kf frequency point, increasing it from the minimum value Kfmin with a step size df, and at each frequency point, changing Km from Kmmin to Kmmax with a step size dm, measuring the changing pulse backtest maximum value Ivs, recording the maximum value Ivs, output control frequency point kfi and output control amplitude kmi at this time, and storing them in the IVi array. After scanning all frequency points, all maximum values ​​Ivs are sorted from large to small; reading from the sorting from large to small, and outputting the control pulse, and then detecting whether the fundamental current in the back-sampled pulse is greater than the CT no-current threshold value. If it is greater, abandoning the parameter and continuing the next search until the optimal control parameter is obtained, and storing it to control the pulse output during line break inspection and polarity inspection.

[0030] Compared with the prior art, the beneficial effect of the through-core current transformer disconnection and polarity inspection system and control method of the present invention is that it detects whether the through-core current transformer is disconnected and whether the polarity (same-name end) is abnormal through a controllable narrow pulse injection method. Specifically,

[0031] 1) The open circuit and polarity inspection of multiple through-core CTs is carried out online by patrol inspection, which does not require manual inspection and will not affect the normal detection of CT and the failure or abnormality of the primary current carrier;

[0032] 2) The pulse output mode is adopted, with short output time and strong anti-interference energy. At the same time, the output interference is reduced to a minimum to avoid interference with other equipment;

[0033] 3) Online inspection of multiple through-core CTs for problems such as disconnection and polarity can be performed, greatly improving work efficiency and reducing costs;

[0034] 4) Due to the online inspection, problems can be found in time and the alarm can be triggered, which is convenient for maintenance and handling of potential accidents;

[0035] 5) Adaptive learning sensing parameters are used for different CTs. Without affecting the normal monitoring of CT, the system's adaptability to different CTs and different wiring is improved, ensuring the detection accuracy and reliability of the detection results.

Brief Description of the Drawings

[0036] Figure 1-Figure 3 It is a structural schematic diagram of current transformer disconnection and polarity detection in the prior art;

[0037] Figure 4 It is a schematic diagram of the framework principle structure in an embodiment of the present invention;

[0038] Figure 5 It is a schematic diagram of the connection structure between the inspection system and the through-core current transformer in an embodiment of the present invention;

[0039] Figure 6 It is a main program logic block diagram of an embodiment of the present invention;

[0040] Figure 7 This is a logic block diagram of CT line break inspection in an embodiment of the present invention;

[0041] Figure 8 This is a logic block diagram of CT polarity inspection in an embodiment of the present invention;

[0042] Fig. 9 It is a logic block diagram of sensing parameter self-adaptation in an embodiment of the present invention;

[0043] Fig.10 Schematic diagram of the CT polarity same or different sign judgment structure in an embodiment of the present invention;

[0044] Fig.11 It is a three-dimensional view of CT pulse induction parameters in an embodiment of the present invention. [Specific implementation method]

[0045] Example:

[0046] Please refer to Figure 4-Figure 5 This embodiment is a through-core current transformer disconnection and polarity inspection system, which includes a multi-channel pulse control and generation module A; a pulse recovery and measurement module B; a switching, pulse control and acquisition module C; a core control, power supply and human-computer interaction and communication module D.

[0047] The multi-channel pulse control and generation module A is composed of a controllable pulse generation circuit KCP[1,2,…,9] and a multi-channel switching switch selection circuit SWA and SWB. The control signals of KCP[1,2,…,9] are Kf[1,2,…,9] and Km[1,2,…,9] respectively, where Kf[1,2,…,9] is the frequency of the control pulse output, and Km[1,2,…,9] is the amplitude of the control pulse output. The multi-channel switching switch selection circuits SWA and SWB have a gating function so that only one controllable pulse is output at the same time. The main function of the multi-channel pulse control and generation module A is to output a pulse with controllable frequency and amplitude. The pulse is led out to two output terminals through the controllable pulse generation circuit KCP. The two output terminals are penetrated from the primary side of the through-core current transformer CT through wires, and the change of the pulse will sense the secondary side of the through-core current transformer CT.

[0048] The pulse recovery and measurement module B is composed of a current Hall sensor HR[1,2,…,9] and a multi-way switching selection circuit SWC. The input of the Hall sensor HR comes from the secondary output of the through-core CT. It measures the induction pulse generated by the multi-way pulse control and generation module A. The multi-way switching selection circuit SWC is responsible for selecting one of the Hall outputs in HR[1,2,…,9], entering the analog measurement loop of the system, and converting it into a digital signal for processing after ADC digital-to-analog conversion.

[0049] The switching, pulse control and acquisition module C consists of four circuit parts: the switching control circuit SMMD, the frequency control circuit FCMD, the amplitude control circuit VCMD and the data acquisition conversion circuit ADIMD. The switching control circuit SMMD is responsible for the pulse output selection control, that is, which KCP is selected for output; the frequency control circuit FCMD and the amplitude control circuit VCMD are responsible for the signal processing and shaping of the output frequency and amplitude; the data acquisition conversion circuit ADIMD contains a low-pass filter, an anti-interference circuit and its ADC acquisition circuit, which is responsible for the signal processing and acquisition of the recovered pulses.

[0050] The core control, power supply, human-computer interaction and communication module D mainly includes the system's power supply POW, the microprocessor and external circuit MCU-MD, the touch screen in the human-computer interaction system and its communication, the Ethernet ETH communication interface connected to the external power monitoring system and its drive circuit part.

[0051] The working principle of the system in this embodiment is as follows Figure 5 As shown, Figure 5The working principle and wiring of the system inspection are indicated in the figure. The through-core current transformers CT1-CT9 are the objects to be inspected. This system mainly inspects whether there is a secondary disconnection or reverse polarity (same-name terminals) in the through-core current transformers CT1-CT9. If reversed, an alarm message will be prompted in the human-computer interaction system or communication, so that maintenance personnel can handle it in time.

[0052] The wiring principle of this system is as follows: The pulse output terminals G1A and G1B pass through the primary side aperture of the through-core current transformer CT1 through the wire, and the incoming direction is the same as the specified direction of the current of the primary current carrier L1, such as Figure 5 , the lead of the secondary output terminal P1 of the through-core current transformer CT is forwardly inserted into the current Hall sensor HR1, and the outgoing line is connected to the load X1 and then to the secondary output terminal P2. When the system inspects CT1, a pulse with variable frequency and variable amplitude will be generated at both ends of G1A and G1B. This pulse will sense the secondary output terminals P1 and P2 through the magnetic field of the through-core current transformer. By measuring the pulse current at both ends of P1 and P2 through the current Hall sensor HR1, it can be determined whether CT1 is broken or the polarity is reversed.

[0053] This embodiment also provides a control method for a through-core current transformer disconnection and polarity inspection system, and its main program logic is as follows: Figure 6 As shown, it includes:

[0054] S1) The main program starts;

[0055] S2) parameter and system initialization;

[0056] S3) Read the number N of patrol CTs and set the patrol number i=1;

[0057] S4) Execute the circuit breaker inspection logic of CTi;

[0058] S5) Execute polarity inspection logic of CTi;

[0059] S6) Let i=i+1, determine whether i is greater than N, if greater, execute subsequent code and logic, and then return to step S3), if not greater, return to step S4);

[0060] In the main program logic, N CTs (N=9 in the present embodiment) are inspected cyclically. The inspection mainly includes CT disconnection inspection and polarity inspection. If a CT is disconnected or polarity is abnormal, an alarm is generated in the human-computer interaction system and in the communication with the power monitoring system, so that the operation and maintenance personnel can deal with the abnormal problem in time.

[0061] The circuit breaker inspection logic in step S4) is as follows: Figure 7As shown, the logic first determines whether the fundamental current IVi0 of the CT is greater than the CT no-current threshold. If it is greater, it is determined that there is current in the CT, and there is no disconnection at this time, and the disconnection judgment logic is directly exited; if the fundamental current IVi0 is less than the CT no-current threshold, a disconnection detection is performed. If this CT has not adaptively learned the pulse output parameters, adaptive learning is performed before detection. The software controls the KCP output amplitude according to the adaptive learning parameter CT[i][1], and the parameter CT[i][2] controls the KCP output frequency to control the output pulse. At the same time, the output value IVi1 of the Hall HR after passing through the bandpass filter is detected. If IVi1 is greater than the set ratio value of the pulse recovery value CT[i][0] that has been adaptively learned before, it is preferably 50% of CT[i][0]. The ratio of 50% is an empirical value and a relatively reliable value. The logic believes that the CT circuit is intact and there is no disconnection. Otherwise, the CT is disconnected and a CT disconnection alarm is issued. Parameters CT[i][0], CT[i][1], and CT[i][2] are the pulse control parameters obtained by CTi after adaptive learning logic learning. Specifically include:

[0062] S41) Calculate the fundamental current value IVi0 of CTi using FFT algorithm;

[0063] S42) determining whether the fundamental current value IVi0 is greater than the no-current threshold value of CTi, if so, the inspection is completed, otherwise, executing step S43);

[0064] S43) determining whether CTi has adaptively learned pulse output parameters. If not, executing CTi sensing parameter adaptive learning logic, and then executing the next step; if it has learned, directly executing the next step;

[0065] S44) reading CT[i][1] and CT[i][2] to control the output pulse;

[0066] S45) obtaining a measured value IVi1 of the pulse through a bandpass filter;

[0067] S46) Determine whether IVi1 is greater than 50% of the adaptively learned pulse recovery value CT[i][0]. If so, the inspection is completed. Otherwise, it is determined that CTi is disconnected, an alarm signal is output, and the inspection is completed.

[0068] The polarity inspection logic in step S5) is as follows: Figure 8As shown, the logic first determines whether the fundamental current IVi0 of the CT is greater than the CT no-current threshold. If it is greater, it is determined that there is current in the CT. It is considered that the primary current carrier of the CT has an unbalanced current or a fault current. Polarity detection should not be performed and the polarity detection logic is directly exited. If the CT detects a broken line, polarity detection cannot be performed and the polarity detection logic is directly exited. The polarity detection mainly compares the width of the same or different signs of the control output pulse IVout and the input pulse IVi of the recovery, as shown in Figure 1. Fig. 9 As shown; if the different-sign width TD2 is greater than the same-sign width TD1, and the different-sign width TD2 is greater than the set ratio value of the output period Tout of the pulse IVout of the control output, preferably 50% of Tout, 50% is an empirical value and a relatively reliable value, then it is considered that the polarity (same-name end) of the CT is connected in reverse, otherwise the polarity connection is correct and the inspection is completed. Specifically including:

[0069] S51) Calculate the fundamental current value IVi0 of CTi using FFT algorithm;

[0070] S52) determining whether the fundamental current value IVi0 is greater than the no-current threshold of CTi, if so, the inspection is completed, otherwise, executing step S53);

[0071] S53) Determine whether CTi is disconnected, if so, the inspection is completed, otherwise, execute the next step;

[0072] S54) reading the parameters CT[i][1] and CT[i][2] in the CTi sensing parameter adaptive learning logic to control the output pulse;

[0073] S55) Obtain the same-sign width TD1 and different-sign width TD2 of the output pulse IVout and the recovered pulse IVi according to the recovered sampling data, and calculate the output pulse width Tout=1 / CT[i][2];

[0074] S56) Determine whether TD2>TD1 and TD2>0.5Tout. If so, it is determined that the polarity of the through-core current transformer CTi is connected in reverse and the inspection is completed. Otherwise, it is determined that the polarity of the through-core current transformer CTi is connected correctly and the inspection is completed.

[0075] The sensing parameter adaptive learning logic in step S43 is as follows: Figure 10-11As shown. Due to the different parameters of through-hole CTs of different models (such as differences in transformation ratio, distributed capacitance and inductance), installation positions, length of secondary leads, etc., after the inspection system pulses are input to the primary side, different models of CTs, different installation positions, and the length of secondary wires will affect the pulses induced on the secondary side. There will be great differences, and in extreme cases there will be no output. To avoid this situation, the sensing parameter adaptive learning logic will automatically change the frequency and amplitude of the pulse output to find the most suitable control output parameters to ensure that the maximum pulse induction input Iv is obtained without affecting the fundamental current output of the CT. For the controllable quantities in the control system of this embodiment: the relationship between the frequency control point Kf, the amplitude control point Km, and the maximum pulse induction input Iv (i.e., the input value of the Hall sensor HR) is as shown below: Fig.11 . The adaptive learning process is mainly about finding the best sensitive point. Under the given initial value, first change the Kf frequency point, and increase it from the minimum value Kfmin with a step size df. At each frequency point, change Km from Kmmin to Kmmax with a step size dm, measure the changing pulse backtest maximum value Ivs, record the maximum value Ivs at this time, output the control frequency point kfi and the output control amplitude kmi, and store them in the IVi array. After scanning all frequency points, sort all the maximum values ​​Ivs from large to small. Read from the sorting from large to small, and output the control to detect whether the fundamental current in the back-sampled pulse is greater than the CT no-current threshold. If it is greater, discard the parameter and continue the next search. The purpose of this logic is to not affect the other load devices X[1,2,…,9] of the through-core CT when monitoring the CT current during output pulse detection (other load devices mainly monitor the CT fundamental current, refer to Figure 2 ). After obtaining the optimal control parameters, they are stored and used to control the pulse output during disconnection inspection and polarity inspection. Specifically include:

[0076] S431) parameter initialization, including setting i=0, minimum frequency Kfmin=1Khz, maximum frequency Kfmax=10Khz, frequency scanning step df=5hz, pulse amplitude minimum Kmmin=5V, pulse amplitude maximum Kmmax=30V and setting pulse amplitude step dm=1V;

[0077] S432) Set the output frequency point \(K_{fi}=K_{fmin}+i\times df\), where \(i = 0, 1,\cdots,p\) and \(p=(K_{fmax}-K_{fmin}) / df - 1\); then change the amplitude output \(K_{mj}\) from \(K_{mmin}\) to \(K_{mmax}\) in steps of \(dm\), where \(j = 0, 1,\cdots,q\) and \(q=(K_{mmax}-K_{mmin}) / dm - 1\); for each amplitude output \(K_{mj}\), there is a corresponding pulse acquisition measurement data \(I_{vj}\). After filtering out the low-frequency components using a low-pass filter, the measured corresponding value is \(I_{vj}\). Finally, find the maximum value \(I_{vs}\) of \(I_{vj}\) in the range from \(0\) to \(q\), i.e., \(I_{vs}=\max(I_{v0},I_{v1},\cdots,I_{vq})\), and store it in the array \(IV_i(IV[i][0],IV[i][1],IV[i][2])\), where

[0078] \(IV[i][0]=I_{vs}\) (the maximum value of the amplitude corresponding to the frequency point \(K_{fi}\));

[0079] \(IV[i][1]=K_{mj}\) (the output amplitude corresponding to the frequency point \(K_{fi}\));

[0080] \(IV[i][2]=K_{fi}\) (the frequency point \(K_{fi}\));

[0081] S433) Determine whether \(K_{fi}<K_{fmax}\) holds. If it does, let \(i = i + 1\) and return to step S432). If not, execute the next step;

[0082] S434) Record the array \(IV_i\) of all frequency points from \(K_{fmin}\) to \(K_{fmax}\) with a change step of \(df\), where \(i = 0, 1,\cdots,p\), to obtain the array set \(IVP\). Sort the array set \(IVP\) in descending order according to \(I_{vs}\) and store it in the array \(CT_Rem[X][3](CT_Rem[x][0],CT_Rem[x][1],CT_Rem[x][2])\). Among them, \(CT_Rem[x][0]=I_{vx}\), \(x = 0, 1,\cdots,p\), and \(I_{vx}\) gradually decreases as the value of \(x\) increases; \(CT_Rem[x][1]=K_{mx}\); \(CT_Rem[x][2]=K_{fx}\); and set the output point serial number \(i = 0\), \(i<x\), \(x = 0, 1,\cdots,p\);

[0083] S435) Read the amplitude control \(K_{mx}\) and frequency point control \(K_{fx}\) according to the serial number \(i\), and output the control pulse; then calculate the fundamental wave current value \(I_{vx0}\) in the pulse acquisition amount \(I_{vx}\);

[0084] S436) Determine whether Ivx0 is greater than the CTx no-flow threshold value. If so, set the sequence number i = i + 1 and return to step S435). If not, record the i output point information into the CTi (CT[i][0], CT[i][1], CT[i][2]) characteristic parameter storage array, where CT[i][0] = Ivx (pulse recovery amplitude); CT[i][1] = Kmx (pulse control amplitude); CT[i][2] = Kfx (pulse control frequency); learning is completed.

[0085] This embodiment provides a through-core current transformer disconnection and polarity inspection system and control method thereof, which detects whether the through-core current transformer is disconnected and whether the polarity (same-name end) is abnormal through a controllable narrow pulse injection method. Specifically,

[0086] 1) The open circuit and polarity inspection of multiple through-core CTs is carried out online by patrol inspection, which does not require manual inspection and will not affect the normal detection of CT and the failure or abnormality of the primary current carrier;

[0087] 2) The pulse output mode is adopted, with short output time and strong anti-interference energy. At the same time, the output interference is reduced to a minimum to avoid interference with other equipment;

[0088] 3) Online inspection of multiple through-core CTs for problems such as disconnection and polarity can be performed, greatly improving work efficiency and reducing costs;

[0089] 4) Due to the online inspection, problems can be found in time and the alarm can be triggered, which is convenient for maintenance and handling of potential accidents;

[0090] 5) Adaptive learning sensing parameters are used for different CTs. Without affecting the normal monitoring of CT, the system's adaptability to different CTs and different wiring is improved, ensuring the detection accuracy and reliability of the detection results.

[0091] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A control method for a through-current transformer disconnection and polarity inspection system, characterized in that: It includes A number of controllable pulse generating circuits KCP, whose pulses are output to the primary side of the through-core current transformer CT; A number of Hall sensors HR, responsible for pulse collection and measurement, the number of which is the same as the controllable pulse generating circuit KCP, and the secondary output terminal of the through-core current transformer CT is forwardly penetrated into the Hall sensor HR; Multi-way switch selection circuits SWA, SWB, SWC, wherein SWA controls the frequency of the output pulses of all controllable pulse generating circuits KCP, SWB controls the amplitude of the output pulses of all controllable pulse generating circuits KCP, and SWC is responsible for selecting the output of a corresponding Hall sensor HR; The switching control circuit SWMD controls and selects one of the controllable pulse generating circuits KCP to output a pulse; The frequency control circuit FCMD and the amplitude control circuit VCMD respectively control the frequency and amplitude of the output pulse and shape it; The data acquisition conversion circuit ADIMD is connected to the multi-way switch selection circuit SWC and is responsible for the signal processing and acquisition of the acquisition pulse; as well as A core control module, electrically connected to the switching control circuit SWMD, the frequency control circuit FCMD, the amplitude control circuit VCMD and the data acquisition conversion circuit ADIMD; The control method of the through-core current transformer disconnection and polarity inspection system comprises the following steps: S1) The main program starts; S2) parameter and system initialization; S3) Read the number of patrol CTs N and set the patrol number i=1; S4) Execute the circuit breaker inspection logic of CTi; S5) Execute the polarity inspection logic of CTi; the polarity inspection logic includes: first determine whether the fundamental current IVi0 of the CT is greater than the CT no-current threshold, if so, directly exit the polarity detection logic, otherwise, determine whether the CT detects a broken line, if detected, directly exit the polarity detection logic; otherwise, perform polarity detection, compare the same and different sign widths of the control output pulse IVout and the recovery input pulse Ivi, if the same sign width TD1 is greater than the different sign width TD2, and TD1 is greater than the set ratio of the output period Tout of the control output pulse IVout, it is considered that the CT polarity connection is correct, otherwise it is determined that the polarity is reversed; S6) Let i=i+1, and determine whether i is greater than N. If so, return to step S3). If not, return to step S4).

2. The control method of the through-core current transformer disconnection and polarity inspection system according to claim 1, characterized in that: The data acquisition conversion circuit ADIMD internally includes a low-pass filter, an anti-interference circuit and an ADC acquisition circuit.

3. The control method of the through-core current transformer disconnection and polarity inspection system according to claim 1, characterized in that: It also includes a power supply for supplying power to the core control module and a human-computer interaction system that communicates with the core control module.

4. The control method of the through-core current transformer disconnection and polarity inspection system according to claim 1, characterized in that: The core control module is in communication with an external power monitoring system.

5. The control method of the through-core current transformer disconnection and polarity inspection system according to claim 1, characterized in that: The pulse output terminal of the controllable pulse generating circuit KCP passes through the primary side aperture of the through-core current transformer through a wire, and the incoming direction is the same as the specified direction of the current of the primary current carrier.

6. The control method of the through-core current transformer disconnection and polarity inspection system according to claim 1, characterized in that: The lead wire of the secondary output terminal P1 of the through-core current transformer CT penetrates the Hall sensor in the forward direction, and the outgoing wire is connected to the load and then to the secondary output terminal P2 of the through-core current transformer CT.

7. The control method of the through-core current transformer disconnection and polarity inspection system according to claim 1, characterized in that: The circuit breaker inspection logic in S4) includes: firstly, determining whether the fundamental current IVi0 of the through-core current transformer CT is greater than the CT no-current threshold value, if so, exiting the circuit breaker inspection logic, otherwise performing a circuit breaker detection; allowing the CT to perform an adaptive learning logic to obtain pulse output parameters CT[i][0], CT[i][1] and CT[i][2]; controlling the output amplitude of the controllable pulse generating circuit KCP according to the parameter CT[i][1], and controlling the output frequency of the controllable pulse generating circuit KCP according to the parameter CT[i][2] to control the output pulse, and at the same time detecting the output value IVi1 of the Hall sensor HR; if IVi1 is greater than the set ratio of the adaptively learned pulse recovery value CT[i][0], it is considered that the CT circuit is intact and there is no circuit breaker; otherwise, it is determined that the CT circuit is disconnected, and a CT circuit breaker alarm is issued.

8. The control method of the through-core current transformer disconnection and polarity inspection system according to claim 7, characterized in that: The adaptive learning includes: under a given initial value, first changing the frequency control point Kf, increasing it from the minimum value Kfmin with a step size df, and at each frequency point, changing the amplitude control point Km from Kmmin to Kmmax with a step size dm, measuring the changing pulse backtest maximum value Ivs, recording the maximum value Ivs, the output control frequency point kfi and the output control amplitude kmi at this time, and storing them in the IVi array. After scanning all frequency points, all maximum values ​​Ivs are sorted from large to small; reading from the sorting from large to small, and outputting the control pulse, and then detecting whether the fundamental current in the back-sampled pulse is greater than the CT no-current threshold value. If it is greater, abandoning the parameter and continuing the next search until the optimal control parameter is obtained, and storing it to control the pulse output during line break inspection and polarity inspection.

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