A power distribution area topology relationship identification system and method of different frequency small current injection

Abstract

A kind of power distribution area topology relationship identification system and method of different frequency small current injection, signal sending device is arranged in each terminal of power distribution area, integrated sending and receiving device is arranged in each node, signal receiving device is arranged at the side of distribution transformer;Signal sending device injects different frequency small current signal into power distribution network according to the starting instruction of main station system;Integrated sending and receiving device, i.e. the function of signal sending device and signal receiving device is integrated;Signal receiving device identifies and restores different frequency small current signal, and sends its related information to main station;Main station system determines the next level of signal sending device by comprehensively identifying the related information of signal, and obtains complete topology relationship by combing each level according to the method.The present application has the advantages of strong anti-interference ability, high identification success rate, adjustable identification frequency according to current frequency, low dependence on injected current intensity, strong practicability and the like.

Description

Technical Field

[0001] This invention belongs to the field of topology relationship identification, specifically relating to a distribution station topology relationship identification system and method with differential frequency low current injection, wherein low current refers to a current signal with a peak value of no more than 100mA. Background Technology

[0002] my country's power distribution network is widely distributed and vast, containing various electrical equipment, resulting in a complex power supply and consumption environment. Currently, there are problems with the untimely and inaccurate acquisition of distribution topology relationships. Users frequently change lines without permission. There is a lack of effective technical solutions to establish the correct topological hierarchy between transformer substations and users. Accurately obtaining topology relationships is crucial for power companies to plan power lines, manage abnormal line losses, and balance three-phase loads.

[0003] To address the need for topology identification in distribution networks, various methods have been developed, including correlation analysis of power frequency zero-crossing sequences, correlation analysis of power outage records, correlation analysis of hourly voltage curves, feature analysis of power frequency distortion equipment intervention in enhanced distribution areas, power frequency voltage distortion analysis, and power frequency current distortion analysis. However, these methods suffer from low accuracy and limited applicability.

[0004] Active current injection is currently the main technology for topology identification. It identifies line topology by injecting characteristic current signals of different frequencies into the power frequency current signal. Compared with other methods, active signal injection has advantages such as simple principle, high success rate, effectiveness, and reliability.

[0005] Because various interference sources exist in the power grid system, such as harmonics and noise, they may confuse or mask the characteristic current signals of different frequencies. Therefore, the active current injection method requires high sensitivity and accuracy from the sensing device.

[0006] CN117117965A discloses a distribution network topology identification system, method, and apparatus based on a magnetic current sensor. It employs a current transmitting device and a magnetic current sensor. The current transmitting device injects a characteristic current signal of a preset frequency into the distribution network. The magnetic current sensor collects current signals from the distribution network lines, filters out background current signals, and obtains a detection signal for identifying the distribution network topology. The resonant frequency of the magnetic current sensor is consistent with the preset frequency. However, the magnetic current sensor in this patent cannot adaptively adjust the identification frequency according to the characteristic current signal frequency; and it lacks specific signal transmission encoding, identification reception, and discrimination procedures, thus its practicality is limited. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a system and method for identifying the topological relationships of distribution radio stations using heterogeneous frequency small current injection.

[0008] The present invention adopts the following technical solution.

[0009] This application claims protection for a distribution station topology identification system with heterogeneous frequency low current injection, comprising a master station system, a signal transmitting device, a signal receiving device, and an integrated transmitting and receiving device, characterized in that:

[0010] Signal transmitting devices are installed at each terminal in the distribution transformer area, integrated transmitting and receiving devices are installed at the identification nodes in the distribution transformer area, and signal receiving devices are installed on the distribution transformer side of the distribution transformer area.

[0011] Each terminal's signal transmitting device is considered as its own equipment. The own equipment receives instructions from the master station system and injects a set specification of low-frequency current signal into the distribution network in a time-sharing manner.

[0012] The integrated transmitting and receiving device and the signal receiving device adjust the signal identification frequency point according to the frequency of the injected heterogeneous small current signal;

[0013] When an integrated transmitting and receiving device or a signal receiving device identifies a small current signal at a different frequency, it sends the relevant information about the identified signal to the main station system.

[0014] The master station system determines the next-level device of each local device based on the identification signal information sent by each integrated transmitting and receiving device or signal receiving device, and uses the next-level device as the local device. It continues to control the integrated transmitting and receiving devices that have not yet determined the next level to inject a small current signal of a set specification into the distribution network until the cascading relationship of all terminals to the distribution transformer side of the distribution area has been determined, and a complete distribution area topology is obtained.

[0015] Further, the following preferred options are included:

[0016] The signal transmitting device is set up separately at the distribution area terminal, or integrated with the power meter, acquisition terminal or branch detection equipment of the distribution area terminal.

[0017] The signal transmitting device includes a terminal communication module, a terminal main control module, and a terminal signal transmitting module;

[0018] After the signal transmitting device receives the topology identification process start command issued by the master station system through the terminal communication module, the terminal main control module adjusts and generates a different frequency small current signal of the set specifications according to the start command, and controls the terminal signal transmitting module to inject the different frequency small current signal into the terminal where the signal transmitting device is located. The terminal communication module sends the result of the injected current to the master station system.

[0019] The specified specifications include the modulation frequency, bit width, duty cycle, feature code, and peak current of the heterogeneous low-current signal.

[0020] The feature code is a set of codes containing transmission information, which includes the ID number of the device that injects the inter-frequency small current signal and the injection time of the inter-frequency small current signal.

[0021] Bit width time is the modulation transmission time of each bit in the feature code, and the modulation transmission time does not exceed 1200ms.

[0022] The modulation frequency is set to 200~1000Hz, and the odd and even harmonic frequencies of the power frequency must be avoided. The peak value of the small current signal at different frequencies should not exceed 100mA.

[0023] The information related to the identification signal includes the injection time of the differential frequency small current signal, the ID number of the device that injected the differential frequency small current signal, the strength of the differential frequency small current signal, the signal identification time, and the signal identification phase.

[0024] The integrated transmitting and receiving device includes a node communication module, a node main control module, a node inter-frequency signal sensing module, a node signal restoration module, and a node signal injection module;

[0025] The node heterogeneous frequency signal sensing module has multiple magnetoelectric stress-coupled sensing elements.

[0026] When the integrated transmitting and receiving device receives the inter-frequency signal receiving instruction sent by the master station system through the node communication module, the node master control module adjusts the identification frequency of the node inter-frequency signal sensing module to be consistent with the frequency of the injected inter-frequency small current signal; the node inter-frequency signal sensing module senses the magnetic field change caused by the inter-frequency small current signal transmitted to the node and converts it into a voltage signal and outputs it to the node signal restoration module;

[0027] The node signal restoration module restores the heterogeneous frequency small current signal transmitted to the node and transmits the obtained signal identification time, signal identification phase, and restored heterogeneous frequency small current signal to the node master control module. The node master control module performs frequency domain analysis and time domain analysis on the restored heterogeneous frequency small current signal to obtain the heterogeneous frequency small current signal injection time, the ID number of the device injecting the heterogeneous frequency small current signal, and the heterogeneous frequency small current signal strength, thereby obtaining identification signal-related information. The node communication module sends the identification signal-related information obtained by the node master control module to the master station system.

[0028] When the integrated transmitting and receiving device receives the topology identification process start command issued by the master station system through the node communication module, the node master control module modulates a different frequency small current signal of the set specifications according to the start command, the node signal injection module injects the different frequency small current signal modulated by the node master control module into the distribution network, and the node communication module sends the result of the injected current to the master station system.

[0029] The node main control module includes a node identification frequency adjustment unit, a node sampling frequency adjustment unit, a node analog-to-digital converter, a node frequency domain analysis unit, a node time domain analysis unit, a node information processing unit, and a signal modulation unit;

[0030] The node identification frequency adjustment unit selects a magnetoelectric stress coupling sensing element in the node heterofrequency signal sensing module whose signal identification frequency is consistent with the frequency of the injected heterofrequency small current signal, and connects it to the node signal restoration module.

[0031] The node sampling frequency adjustment unit adjusts the sampling frequency of the node analog-to-digital converter to ensure that it is not lower than 4kHz and is an integer multiple of the power frequency and the injected signal frequency.

[0032] The node analog-to-digital converter samples the restored small current signal of different frequencies input from the node signal restoration module and inputs it to the node frequency domain analysis unit.

[0033] The node frequency domain analysis unit performs discrete Fourier transform on the sampled signal to separate the background signal and the different frequency small current signal in the frequency domain, and records the intensity of the different frequency small current signal.

[0034] The node time-domain analysis unit demodulates and decodes the separated inter-frequency small current signal in the time domain to obtain the inter-frequency small current signal injection time and the ID number of the device that injected the inter-frequency small current signal contained in the feature code of the inter-frequency small current signal.

[0035] The node information processing unit combines the injection time of the inter-frequency small current signal obtained by the node time domain analysis unit, the ID number of the device injecting the inter-frequency small current signal, the strength of the inter-frequency small current signal obtained by the node frequency domain analysis unit, and the signal identification time and signal identification phase transmitted by the node signal restoration module into a record as identification signal related information, and transmits it to the node communication module.

[0036] The signal modulation unit modulates a small current signal of a different frequency with a set specification according to the start command of the topology identification process, and transmits the modulated signal to the node signal injection module.

[0037] The node signal restoration module records the time of receiving the voltage signal as the signal identification time; it amplifies, filters, rectifies, and regulates the received voltage signal; then, based on the relationship between the calibrated voltage output value of the magnetoelectric stress-coupled sensing element and the heterogeneous small current signal, it calculates the magnitude of the injected heterogeneous small current signal, or calculates the magnetic field strength induced by the sensing element based on the output voltage of the magnetoelectric stress-coupled sensing element, and then calculates the magnitude of the heterogeneous small current signal transmitted to the node position based on the relationship between the magnetic field strength and the magnitude of the heterogeneous small current signal, thereby restoring the heterogeneous small current signal transmitted to the node position; the initial phase of the restored heterogeneous small current signal is recorded as the signal identification phase.

[0038] When multiple signal transmitting devices or integrated transmitting and receiving devices simultaneously inject small current signals of different frequencies, the node identification frequency adjustment unit selects multiple magnetoelectric stress coupling sensing elements with different identification frequencies and connects the selected multiple sensing elements to the node signal restoration module.

[0039] The signal receiving device includes a transformer-side communication module, a transformer-side main control module, a transformer-side inter-frequency signal sensing module, and a transformer-side signal restoration module.

[0040] The transformer-side frequency signal sensing module has multiple magnetoelectric stress-coupled sensing elements.

[0041] When the signal receiving device receives the inter-frequency signal receiving instruction sent by the main station system through the distribution transformer side communication module, the distribution transformer side main control module adjusts the identification frequency of the distribution transformer side inter-frequency signal sensing module to be consistent with the frequency of the injected inter-frequency small current signal; the distribution transformer side inter-frequency signal sensing module senses the magnetic field change caused by the inter-frequency small current signal transmitted to the distribution transformer side, and converts it into a voltage signal and outputs it to the distribution transformer side signal restoration module.

[0042] The transformer-side signal restoration module restores the inter-frequency low-current signal transmitted to the transformer side and transmits the obtained signal identification time, signal identification phase, and restored inter-frequency low-current signal to the transformer-side main control module. The transformer-side main control module performs frequency domain analysis and time domain analysis on the restored inter-frequency low-current signal to obtain the inter-frequency low-current signal injection time, the ID number of the device injecting the inter-frequency low-current signal, and the inter-frequency low-current signal strength, thereby obtaining identification signal-related information. The transformer-side communication module sends the identification signal-related information obtained by the transformer-side main control module to the master station system.

[0043] The transformer-side main control module includes a transformer-side identification frequency adjustment unit, a transformer-side sampling frequency adjustment unit, a transformer-side analog-to-digital converter, a transformer-side frequency domain analysis unit, a transformer-side time domain analysis unit, and a transformer-side information processing unit;

[0044] The transformer-side identification frequency adjustment unit selects a magnetoelectric stress coupling sensing element in the transformer-side inter-frequency signal sensing module whose signal identification frequency is consistent with the frequency of the injected inter-frequency small current signal, and connects it to the transformer-side signal restoration module.

[0045] The transformer-side sampling frequency adjustment unit adjusts the sampling frequency of the transformer-side analog-to-digital converter to ensure that it is not lower than 4kHz and is an integer multiple of the power frequency and the injected signal frequency.

[0046] The transformer-side analog-to-digital converter samples the restored small-current signal of different frequencies input from the transformer-side signal restoration module and inputs it to the transformer-side frequency domain analysis unit.

[0047] The frequency domain analysis unit on the distribution transformer side performs discrete Fourier transform on the sampled signal to separate the background signal and the small current signal of different frequencies in the frequency domain, and records the intensity of the small current signal of different frequencies.

[0048] The distribution transformer side time domain analysis unit demodulates and decodes the separated inter-frequency small current signal in the time domain to obtain the inter-frequency small current signal injection time and the ID number of the device that injected the inter-frequency small current signal contained in the inter-frequency small current signal feature code.

[0049] The transformer-side information processing unit combines the injection time of the inter-frequency small current signal obtained by the transformer-side time domain analysis unit, the ID number of the device injecting the inter-frequency small current signal, the intensity of the inter-frequency small current signal obtained by the transformer-side frequency domain analysis unit, and the signal identification time and signal identification phase transmitted by the transformer-side signal restoration module, and records them as identification signal related information, and transmits them to the transformer-side communication module.

[0050] When multiple signal transmitting devices or integrated transmitting and receiving devices simultaneously inject small current signals of different frequencies, the transformer-side identification frequency adjustment unit selects multiple magnetoelectric stress coupling sensing elements with different identification frequencies and connects the selected sensing elements to the transformer-side signal restoration module.

[0051] This application also claims protection for a method for identifying the topology of a distribution station area based on the aforementioned topology identification system using inter-frequency small current injection, the method comprising the following:

[0052] Step 1: Set the signal transmitting device of each terminal as the device of this level;

[0053] Step 2: The local equipment receives instructions from the master station system to inject a small current signal of a set specification into the distribution network in a time-sharing manner; the integrated transmitting and receiving device and the signal receiving device adjust the signal identification frequency point according to the frequency of the injected small current signal;

[0054] Step 3: After receiving the heterogeneous frequency low-current signal, the integrated transmitting and receiving device or signal receiving device sends the relevant information of the identified signal to the main station system; the relevant information includes the heterogeneous frequency low-current signal injection time, the ID number of the device that injected the heterogeneous frequency low-current signal, the heterogeneous frequency low-current signal strength, the signal identification time, and the signal identification phase;

[0055] Step 4: The main station system identifies the next level device based on the identification signal information sent by each integrated transmitting and receiving device or signal receiving device;

[0056] Step 5: Determine whether the cascading relationship of all terminals to the distribution transformer side of the distribution area has been determined; if not, take the integrated transmitting and receiving device in the next level as the device of this level, and return the device of this level that has not determined the next level to Step 1; if yes, the complete topology relationship is obtained.

[0057] Further, the following preferred options are included:

[0058] Step 4 specifically includes:

[0059] 4.1 The main station system determines the scope of the next level equipment for each local equipment based on the comparison results between the ID number of the device that injects the inter-frequency small current signal and the ID number of each local equipment in the relevant information of each identification signal received, and the principle that the inter-frequency small current signal injection time of the local equipment should be earlier than the signal identification time.

[0060] 4.2 Determine whether there are multiple corresponding identification signals for each local device. If there are multiple corresponding identification signals for a certain local device, retain the identification signal with the larger signal strength of the different frequency small current signal as the valid signal. Otherwise, directly use the identification signal as the valid signal.

[0061] 4.3 Determine that the next level of each device is an integrated transmitting and receiving device or a signal receiving device that has identified the corresponding valid signal, and obtain the working phase when the device is a single-phase device by identifying the signal phase.

[0062] Another aspect of this application discloses an electronic device, including a processor and a storage medium; characterized in that:

[0063] The storage medium is used to store instructions;

[0064] The processor is configured to operate according to the instructions to execute the distribution station topology identification method based on the aforementioned differential frequency small current injection.

[0065] This application also discloses a computer-readable storage medium storing a computer program thereon, characterized in that, when the program is executed by a processor, it implements the method for identifying the topological relationship of distribution station areas by injecting small currents at different frequencies.

[0066] The beneficial effects of this invention are that, compared with the prior art,

[0067] (1) Strong signal-to-noise ratio: The topology relationship identification signal receiving device using magnetoelectric stress coupling sensing element has unique resonance characteristics. Utilizing the resonance characteristics, it can effectively acquire and identify small current signals of different frequencies under complex background current conditions. The device has outstanding filtering and anti-interference capabilities.

[0068] (2) Low dependence on injection current intensity: Due to the ultra-high sensitivity and excellent frequency selection characteristics of the signal receiving device, it can accurately acquire weak small current signals of different frequencies, thereby reducing the requirement for injection current; compared with the existing current transformer method which requires several A or more current, the present invention utilizes the ultra-sensitive characteristics of the signal receiving device to realize topological relationship identification using mA-level small current injection; through this sensor, the injection current can be significantly reduced while ensuring the accuracy of identification, thereby improving stability and safety.

[0069] (3) High recognition success rate: This system and method for topology relationship recognition of distribution area, based on the ultra-high sensitivity and filtering anti-interference capability of the topology relationship recognition signal receiving device, can effectively receive and identify small current signals of different frequencies, thereby significantly improving the recognition success rate of topology relationship recognition;

[0070] (4) The present invention also has outstanding advantages such as the ability to adapt and adjust the identification frequency according to the current frequency and strong practicality. Attached Figure Description

[0071] Figure 1 This is a diagram of a topology identification system model;

[0072] Figure 2 This is a schematic diagram of a signal transmitting device;

[0073] Figure 3 This is a schematic diagram of the signal waveform injected into the power distribution network by the signal transmitting device;

[0074] Figure 4 This is a schematic diagram of an integrated transmitting and receiving device;

[0075] Figure 5 It is the basic structure of a magnetoelectric stress-coupled sensing element;

[0076] Figure 6 This is a schematic diagram of a signal receiving device;

[0077] Figure 7 It is the spectrum identified by the integrated transmitting and receiving device or the signal receiving device;

[0078] Figure 8 This is a flowchart of the topology relationship identification method;

[0079] Figure 9 This is a flowchart of the main site system's method for organizing topological relationships. Detailed Implementation

[0080] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, other embodiments obtained by those skilled in the art without creative effort are all within the protection scope of this invention.

[0081] This invention proposes a distribution station topology identification system with heterogeneous frequency low current injection, comprising a master station system, a signal transmitting device, a signal receiving device, and an integrated transmitting and receiving device:

[0082] See appendix Figure 1 Signal transmitting devices are installed at each terminal in the distribution transformer area, integrated transmitting and receiving devices are installed at the identification nodes in the distribution transformer area, and signal receiving devices are installed on the distribution transformer side of the distribution transformer area.

[0083] The signal transmitting device can be installed separately in the distribution area terminal, or it can be integrated with the distribution area terminal's energy meter, data acquisition terminal, or branch monitoring equipment.

[0084] Each terminal's signal transmitting device is considered as its own equipment. The own equipment receives instructions from the master station system and injects a set specification of low-frequency current signal into the distribution network in a time-sharing manner.

[0085] The signal transmitting device receives the topology identification process start command sent by the master station system, and injects a low-frequency current signal of a set specification into the distribution network according to the command requirements. Then, it reports the low-frequency current signal injection result to the master station system. The reporting result is either successful or unsuccessful. The specification of the low-frequency current signal can be set in advance on the signal transmitting device or by the topology identification process start command sent by the master station system.

[0086] The specifications include the modulation frequency, bit width, duty cycle, feature code, and peak current of the differential frequency low current signal;

[0087] The feature code is a set of codes containing transmission information, which includes the ID number of the device that injects the inter-frequency small current signal and the injection time of the inter-frequency small current signal.

[0088] The ratio of the high-level pulse width of the modulated signal to the modulation period time during duty cycle;

[0089] Bit width time is the modulation transmission time of each bit in the feature code, and the modulation transmission time does not exceed 1200ms;

[0090] The modulation frequency should be set as high as possible between 200 and 1000 Hz, and should avoid the odd and even harmonic frequencies of the power frequency. The peak value of the small current signal at different frequencies should not exceed 100mA.

[0091] The signal transmitting device is described in the appendix. Figure 2 The system includes a terminal communication module, a terminal main control module, and a terminal signal transmission module. After receiving the topology identification process start command from the master station system via the terminal communication module, the terminal main control module adjusts and generates a low-frequency, heterogeneous current signal of a set specification according to the start command, and controls the terminal signal transmission module to inject the heterogeneous current signal into the terminal where the signal transmission device is located. The terminal communication module then sends the result of the injected current to the master station system. The terminal communication module uses LoRa or RS485 for communication; the terminal main control module uses pulse width modulation technology to generate the heterogeneous current signal of the set specification.

[0092] See appendix Figure 3 This is an example of a signal waveform injected into the power distribution network by a signal transmitting device. Here, Tw is the bit width time; Th is the high-level pulse width time; and Ts is the modulation period time. Each bit width time segment is adjacent to the next. Within each bit width time segment, a specific simplified representation method can be used to depict the modulation period that appears continuously and has a level value of 0.

[0093] The integrated transmitting and receiving device and the signal receiving device select / adjust the signal identification frequency point according to the frequency of the injected heterogeneous small current signal;

[0094] The integrated transmitting and receiving device can be installed separately at the line node, or it can be integrated with other devices such as acquisition terminals or branch monitoring equipment located at the line node.

[0095] See appendix Figure 4 The integrated transmitting and receiving device includes a node communication module, a node main control module, a node inter-frequency signal sensing module, a node signal restoration module, and a node signal injection module;

[0096] The node heterogeneous frequency signal sensing module has multiple magnetoelectric stress-coupled sensing elements.

[0097] When the integrated transmitting and receiving device receives the inter-frequency signal reception command sent by the master station system through the node communication module, the node master control module adjusts the identification frequency of the node inter-frequency signal sensing module to be consistent with the frequency of the injected inter-frequency small current signal; the node inter-frequency signal sensing module senses the magnetic field change caused by the inter-frequency small current signal transmitted to the node and converts it into a voltage signal, which is then output to the node signal restoration module; the node signal restoration module restores the inter-frequency small current signal transmitted to the node and transmits the obtained signal identification time, signal identification phase, and restored inter-frequency small current signal to the node master control module; the node master control module performs frequency domain analysis and time domain analysis on the restored inter-frequency small current signal to obtain the inter-frequency small current signal injection time, the ID number of the device injecting the inter-frequency small current signal, and the inter-frequency small current signal strength, thereby obtaining identification signal related information; the node communication module sends the identification signal related information obtained by the node master control module to the master station system; the identification signal related information includes the inter-frequency small current signal injection time, the ID number of the device injecting the inter-frequency small current signal, the inter-frequency small current signal strength, the signal identification time, and the signal identification phase.

[0098] When the integrated transmitting and receiving device receives the topology identification process start command issued by the master station system through the node communication module, the node master control module modulates a different frequency small current signal of the set specification according to the start command, the node signal injection module injects the different frequency small current signal modulated by the node master control module into the node where the signal transmitting device is located in the distribution network, and the node communication module sends the result of the injected current to the master station system.

[0099] Magnetoelectric stress-coupled sensing elements possess frequency selectivity, enabling them to effectively acquire and identify small current signals of different frequencies with the same frequency as their identification frequency under complex background current conditions. They also exhibit strong filtering and anti-interference capabilities. The identification frequency is the bending resonant frequency of the magnetoelectric stress-coupled sensing element.

[0100] The magnetoelectric stress-coupled sensing element used in this invention includes a magnetostrictive layer and a piezoelectric layer; see appendix. Figure 5 The basic sensing structure of the magnetoelectric stress-coupled sensing element used in this invention consists of a magnetostrictive layer composed of multiple layers of magnetostrictive material, symmetrically arranged on the upper and lower sides of a piezoelectric layer composed of piezoelectric material, forming a magnetoelectric composite layer. The magnetoelectric stress-coupled sensing element can sense a magnetic field component H parallel to the long side of its magnetoelectric composite layer. The relationship between the thickness of the magnetoelectric composite layer and the thicknesses of the magnetostrictive layer and the piezoelectric layer is as follows:

[0101] ;

[0102] Where w is the thickness of the magnetostrictive layer, the magnetostrictive layers on the upper and lower sides of the piezoelectric layer are of equal thickness, both being w, z is the thickness of the piezoelectric layer, and d is the thickness of the magnetoelectric composite layer.

[0103] The magnetostrictive layer exhibits a magnetostrictive effect; it can sense changes in the external magnetic field and utilize this effect to generate stress changes that are transmitted to the piezoelectric layer. The piezoelectric layer is composed of a piezoelectric material and a flexible electrode material. Through the magnetoelectric stress coupling effect generated by the combination of the piezoelectric layer and the magnetostrictive layer, and utilizing the piezoelectric effect of the piezoelectric material, the stress deformation of the magnetostrictive layer on the piezoelectric layer is converted into a voltage, which is output by two flexible electrodes symmetrically positioned on the upper and lower sides of the piezoelectric material within the piezoelectric layer.

[0104] The node main control module includes a node identification frequency adjustment unit, a node sampling frequency adjustment unit, a node analog-to-digital converter, a node frequency domain analysis unit, a node time domain analysis unit, a node information processing unit, and a signal modulation unit;

[0105] The node identification frequency adjustment unit can achieve adaptive adjustment of the identification frequency of the node heterogeneous frequency signal sensing module through any of the following preferred schemes:

[0106] In a preferred embodiment of the present invention, the node inter-frequency signal sensing module includes an array of multiple magnetoelectric stress-coupled sensing elements, each with a different identification frequency. By selecting a magnetoelectric stress-coupled sensing element in the node inter-frequency signal sensing module whose signal identification frequency matches the frequency of the injected inter-frequency small current signal, and connecting it to the node signal restoration module, the effect of aligning the identification frequency of the node inter-frequency signal sensing module with the frequency of the injected inter-frequency small current signal can be achieved.

[0107] In another preferred embodiment, multiple magnetoelectric stress-coupled sensing elements with adjustable characteristic parameters are set in the node heterogeneous frequency signal sensing module. Any one of these sensing elements is selected, and its identification frequency is adjusted so that the bending resonant frequency matches the frequency of the injected heterogeneous frequency small current signal. This adjusted element is then connected to the node signal restoration module. Those skilled in the art can adjust the bending resonant frequency using the following formula:

[0108]

[0109] Where f is the bending resonant frequency; l is the length of the magnetoelectric composite layer; ρ is the average density of the magnetoelectric composite layer; s is the average flexibility coefficient of the magnetoelectric composite layer, which describes the material's ability to deform under force. The higher the flexibility coefficient, the easier the material is to deform, and it is a parameter inherent in the magnetostrictive and piezoelectric layers themselves; n is a positive integer representing the vibration level of the magnetoelectric composite layer. When the vibration level is 1, i.e., n=1, the calculated bending resonant frequency that is the same as the frequency of the small current signal to be measured is the bending resonant frequency with the highest matching degree between the magnetoelectric stress-coupled sensing element and the small current signal to be measured, enabling the magnetoelectric stress-coupled sensing element to achieve the highest matching degree. The piezoelectric layer voltage output value of the sensing element is the largest. When the vibration level is 2, that is, n=2, the calculated bending resonant frequency that is the same as the frequency of the heterogeneous small current signal is the bending resonant frequency with the second highest matching degree between the magnetoelectric stress-coupled sensing element and the measured heterogeneous small current signal. At this bending resonant frequency, the piezoelectric layer voltage output value of the magnetoelectric stress-coupled sensing element is the second largest. The larger the value of the vibration level n, the lower the matching degree between the magnetoelectric stress-coupled sensing element and the measured heterogeneous small current signal corresponding to the calculated bending resonant frequency that is the same as the frequency of the heterogeneous small current signal, and the smaller the piezoelectric layer voltage output value of the magnetoelectric stress-coupled sensing element.

[0110] The node sampling frequency adjustment unit adjusts the sampling frequency of the node analog-to-digital converter to ensure it is not lower than 4kHz and is an integer multiple of the power frequency and the injected signal frequency. Since the peak value of the power frequency current in the distribution network is much higher than the peak value of the injected heterogeneous small current signal, the power frequency current signal is considered as noise, i.e., a background signal, in the heterogeneous small current signal identified by the signal receiving device. Therefore, the sampling frequency is also defined as an integer multiple of the power frequency.

[0111] The node analog-to-digital converter samples the restored inter-frequency small current signal from the node signal restoration module and transmits the sampled discrete signal to the node frequency domain analysis unit. The node frequency domain analysis unit performs a discrete Fourier transform on the sampled signal to separate the background signal and the inter-frequency small current signal in the frequency domain and records the inter-frequency small current signal intensity. The node time domain analysis unit demodulates and decodes the separated inter-frequency small current signal in the time domain to obtain the inter-frequency small current signal injection time and the ID number of the device that injected the inter-frequency small current signal contained in the inter-frequency small current signal feature code. The node information processing unit combines the inter-frequency small current signal injection time and the ID number of the device that injected the inter-frequency small current signal obtained by the node time domain analysis unit, the inter-frequency small current signal intensity obtained by the node frequency domain analysis unit, and the signal identification time and signal identification phase transmitted from the node signal restoration module into a record as identification signal related information and transmits it to the node communication module.

[0112] The signal modulation unit modulates a small current signal of a different frequency with a set specification according to the start command of the topology identification process, and transmits the modulated signal to the node signal injection module.

[0113] The node signal restoration module records the time of receiving the voltage signal as the signal identification time. It amplifies, filters, rectifies, and regulates the received voltage signal. Then, based on the calibrated relationship between the voltage output value of the magnetoelectric stress-coupled sensing element and the heterogeneous small current signal, it calculates the magnitude of the injected heterogeneous small current signal. Alternatively, it calculates the magnetic field strength sensed by the sensing element based on the output voltage of the magnetoelectric stress-coupled sensing element, and then calculates the magnitude of the heterogeneous small current signal transmitted to the node location based on the relationship between the magnetic field strength and the magnitude of the heterogeneous small current signal. This allows it to restore the heterogeneous small current signal transmitted to the node location. The initial phase of the restored heterogeneous small current signal is recorded as the signal identification phase. The magnetic field strength sensed by the sensing element can be calculated from the output voltage of the magnetoelectric stress-coupled sensing element using the following formula:

[0114]

[0115] in, It is the piezoelectric layer voltage output value of the heterogeneous frequency signal sensor. It is the piezoelectric layer resonance quality factor, which is the degree of loss caused by internal friction due to lattice deformation during resonance, and is a parameter of the material itself; It refers to the AC magnetic field strength that can be sensed at the installation location of the heterogeneous frequency signal sensor. It is the piezomagnetic coefficient of the magnetostrictive layer. It is the coupling factor of the magnetostrictive layer, which is the conversion efficiency from strain in the magnetostrictive layer to strain in the piezoelectric layer, and is a parameter of the magnetostrictive layer itself; It is the piezoelectric coefficient of the piezoelectric layer. It is the thickness of the piezoelectric layer. It is the vacuum permittivity. It is the relative permittivity of the magnetostrictive layer.

[0116] Since the waveform of the output voltage, except for the peak value, should be consistent with the sensed differential frequency small current signal, comparing the restored differential frequency small current signal with the parameters in the differential frequency small current signal setting specifications, except for the peak value of the injected current, can achieve the effect of determining whether the sensed differential frequency small current signal is the injected differential frequency small current signal; at the same time, the gain ratio can be calculated. The gain ratio is the ratio of the signal strength at the receiving end and the transmitting end at the identification frequency point, that is, the ratio of the differential frequency small current signal strength obtained from the frequency domain to the injected differential frequency small current signal strength.

[0117] When multiple signal transmitting devices or integrated transmitting and receiving devices simultaneously inject small current signals of different frequencies, the node identification frequency adjustment unit can adapt and adjust the identification frequency of the node's different frequency signal sensing module through any of the following preferred schemes:

[0118] In a preferred embodiment of the present invention, the node heterogeneous frequency signal sensing module includes an array of multiple magnetoelectric stress-coupled sensing elements with different identification frequencies. By selecting multiple magnetoelectric stress-coupled sensing elements with different identification frequencies and connecting the selected multiple sensing elements to the node signal restoration module, the effect of simultaneously identifying multiple injected heterogeneous frequency small current signals can be achieved.

[0119] In another preferred embodiment, multiple magnetoelectric stress-coupled sensing elements with adjustable characteristic parameters are set in the node heterofrequency signal sensing module. The bending resonant frequency of a magnetoelectric stress-coupled sensing element is adjusted for each of the simultaneously injected heterofrequency small current signals, and then connected to the node signal restoration module to achieve the effect of simultaneously identifying multiple injected heterofrequency small current signals.

[0120] When an integrated transmitting and receiving device identifies a small current signal at a different frequency, it sends the relevant information about the identified signal to the main station system.

[0121] The signal receiving device can be installed separately on the distribution transformer side of the distribution area, or it can be integrated with the acquisition terminal or branch monitoring equipment located on the distribution transformer side of the distribution area.

[0122] The signal receiving device, after receiving the start command sent by the master station system, identifies and restores the inter-frequency small current signal injected into the distribution network by the signal transmitting device, and records the identified and restored signal as the identification signal; the signal receiving device also has the function of sampling inter-frequency small current signals, and can demodulate the feature code information at the identification frequency point and send the relevant information of the identification signal to the master station system for storage; the relevant information of the identification signal mainly includes the signal identification time, signal identification phase, inter-frequency small current signal strength, and information contained in the feature code, etc.

[0123] The signal receiving device is described in the appendix. Figure 6 It includes a transformer-side communication module, a transformer-side main control module, a transformer-side inter-frequency signal sensing module, and a transformer-side signal restoration module;

[0124] Specifically, the signal receiving device receives the inter-frequency signal receiving command sent by the master station system through the distribution transformer-side communication module. The distribution transformer-side main control module adjusts the identification frequency of the distribution transformer-side inter-frequency signal sensing module to match the frequency of the injected inter-frequency small current signal. The distribution transformer-side inter-frequency signal sensing module senses the magnetic field change caused by the inter-frequency small current signal transmitted to the distribution transformer side and converts it into a voltage signal, which is then output to the distribution transformer-side signal restoration module. The distribution transformer-side signal restoration module restores the inter-frequency small current signal transmitted to the distribution transformer side and transmits the obtained signal identification time, signal identification phase, and restored inter-frequency small current signal to the distribution transformer-side main control module. The distribution transformer-side main control module performs frequency domain analysis and time domain analysis on the restored inter-frequency small current signal to obtain the inter-frequency small current signal injection time, the ID number of the device injecting the inter-frequency small current signal, and the inter-frequency small current signal strength, thereby obtaining identification signal-related information. The distribution transformer-side communication module sends the identification signal-related information obtained by the distribution transformer-side main control module to the master station system. The distribution transformer-side communication module uses LoRa or RS485 to implement communication functionality.

[0125] The transformer-side main control module includes a transformer-side identification frequency adjustment unit, a transformer-side sampling frequency adjustment unit, a transformer-side analog-to-digital converter, a transformer-side frequency domain analysis unit, a transformer-side time domain analysis unit, and a transformer-side information processing unit;

[0126] The transformer-side identification frequency adjustment unit can achieve adaptive adjustment of the identification frequency of the transformer-side inter-frequency signal sensing module through any of the following preferred schemes:

[0127] In a preferred embodiment of the present invention, the transformer-side inter-frequency signal sensing module includes an array of multiple magnetoelectric stress-coupled sensing elements, each with a different identification frequency. By selecting a magnetoelectric stress-coupled sensing element in the transformer-side inter-frequency signal sensing module whose signal identification frequency matches the frequency of the injected inter-frequency small current signal, and connecting it to the transformer-side signal restoration module, the effect of aligning the identification frequency of the transformer-side inter-frequency signal sensing module with the frequency of the injected inter-frequency small current signal can be achieved.

[0128] In another preferred embodiment, multiple magnetoelectric stress-coupled sensing elements with adjustable characteristic parameters are set in the transformer-side inter-frequency signal sensing module. Any magnetoelectric stress-coupled sensing element is selected, and its identification frequency is adjusted so that the bending resonant frequency is consistent with the frequency of the injected inter-frequency small current signal. Then, it is connected to the transformer-side signal restoration module.

[0129] The transformer-side sampling frequency adjustment unit adjusts the sampling frequency of the transformer-side analog-to-digital converter to ensure that it is not lower than 4kHz and is an integer multiple of the power frequency and the injected signal frequency.

[0130] The transformer-side analog-to-digital converter samples the restored inter-frequency small current signal from the transformer-side signal restoration module and transmits it to the transformer-side frequency domain analysis unit. The transformer-side frequency domain analysis unit performs a discrete Fourier transform on the sampled signal to separate the background signal and the inter-frequency small current signal in the frequency domain and records the inter-frequency small current signal strength. The transformer-side time domain analysis unit demodulates and decodes the separated inter-frequency small current signal in the time domain to obtain the inter-frequency small current signal injection time and the ID number of the device that injected the inter-frequency small current signal contained in the inter-frequency small current signal feature code. The transformer-side information processing unit combines the inter-frequency small current signal injection time and the ID number of the device that injected the inter-frequency small current signal obtained by the transformer-side time domain analysis unit, the inter-frequency small current signal strength obtained by the transformer-side frequency domain analysis unit, and the signal identification time and signal identification phase transmitted from the transformer-side signal restoration module into a record as identification signal related information and transmits it to the transformer-side communication module.

[0131] The transformer-side signal restoration module records the time of receiving the voltage signal as the signal identification time; it amplifies, filters, rectifies, and regulates the received voltage signal; then, based on the relationship between the calibrated voltage output value of the magneto-electric stress-coupled sensing element and the inter-frequency small current signal, it calculates the magnitude of the injected inter-frequency small current signal, or calculates the magnetic field strength induced by the sensing element based on the output voltage of the magneto-electric stress-coupled sensing element, and then calculates the magnitude of the inter-frequency small current signal transmitted to the transformer-side location based on the relationship between the magnetic field strength and the magnitude of the inter-frequency small current signal, thereby restoring the inter-frequency small current signal transmitted to the transformer-side; the initial phase of the restored inter-frequency small current signal is recorded as the signal identification phase.

[0132] When multiple signal transmitting devices or integrated transmitting and receiving devices simultaneously inject small current signals of different frequencies, the transformer-side identification frequency adjustment unit can adapt and adjust the identification frequency of the transformer-side differential frequency signal sensing module through any of the following preferred schemes:

[0133] In a preferred embodiment of the present invention, the transformer-side inter-frequency signal sensing module includes an array of multiple magnetoelectric stress-coupled sensing elements with different identification frequencies. By selecting multiple magnetoelectric stress-coupled sensing elements with different identification frequencies and connecting the selected multiple sensing elements to the transformer-side signal restoration module, the effect of simultaneously identifying multiple injected inter-frequency small current signals can be achieved.

[0134] In another preferred embodiment, multiple magnetoelectric stress-coupled sensing elements with adjustable characteristic parameters are set in the transformer-side inter-frequency signal sensing module. The bending resonant frequency of a magnetoelectric stress-coupled sensing element is adjusted for each of the simultaneously injected inter-frequency small current signals, and then connected to the transformer-side signal restoration module to achieve the effect of simultaneously identifying multiple injected inter-frequency small current signals.

[0135] See appendix Figure 7 It displays the spectrum identified by the integrated transmitting and receiving device or signal receiving device, by Figure 7 It can be seen that the normalized signal strength at the identification frequency point is significantly improved. In addition, since the signal strength of the power frequency signal in the distribution network is much greater than the strength of the injected small current signal of different frequencies, even if the voltage output obtained by the sensing element from the power frequency signal is small, the normalized signal strength obtained from the identification of the power frequency signal in the spectrum diagram identified by the integrated transmitting and receiving device or the signal receiving device is slightly greater than the normalized signal strength at the identification frequency point.

[0136] When a signal receiving device identifies a small current signal at a different frequency, it sends the relevant information about the identified signal to the main station system.

[0137] The master station system determines the next-level device of each local device based on the identification signal information sent by each integrated transmitting and receiving device or signal receiving device, and uses the next-level device as the local device. It continues to control the integrated transmitting and receiving devices that have not yet determined the next level to inject a small current signal of a set specification into the distribution network until the cascading relationship of all terminals to the distribution transformer side of the distribution area has been determined, and a complete distribution area topology is obtained.

[0138] This application also discloses a method for identifying the topology of distribution substations based on the aforementioned heterogeneous frequency small current injection system; see appendix. Figure 8 This includes setting each signal transmitting device as the local level device, injecting a different frequency small current signal into the local level device, adjusting the identification frequency points of the integrated transmitting and receiving device and the signal receiving device, after the integrated transmitting and receiving device or the signal receiving device receives the different frequency small current signal, reporting the identification signal-related information to the main station system, confirming the next level device of the local level device, and determining whether all levels have been completed. If not, the next level is taken as the local level, and the integrated transmitting and receiving devices that have not determined the next level continue to inject different frequency small current signals; if so, a complete topology relationship is obtained.

[0139] Step 1: Set the signal transmitting device of each terminal to the level of the device.

[0140] Step 2: The local equipment receives instructions from the master station system to inject a small current signal of a set specification into the distribution network in a time-sharing manner; the integrated transmitting and receiving device and the signal receiving device adjust the signal identification frequency point according to the frequency of the injected small current signal.

[0141] Step 3: After receiving the heterogeneous frequency low-current signal, the integrated transmitting and receiving device or signal receiving device sends the relevant information of the identified signal to the main station system; the relevant information includes the heterogeneous frequency low-current signal injection time, the ID number of the device that injected the heterogeneous frequency low-current signal, the heterogeneous frequency low-current signal strength, the signal identification time, and the signal identification phase.

[0142] Step 4: The main station system, based on the identification signal information sent by each integrated transmitting and receiving device or signal receiving device, confirms the topological relationship between the integrated transmitting and receiving device or signal receiving device that received the identification signal and the equipment at this level, thereby identifying the next-level equipment of this level; see appendix. Figure 9 Step 4 specifically includes the following steps:

[0143] 4.1 The main station system determines the scope of the next level equipment for each local equipment based on the comparison results between the ID number of the device that injects the inter-frequency small current signal and the ID number of each local equipment in the relevant information of each identification signal received, and the principle that the inter-frequency small current signal injection time of the local equipment should be earlier than the signal identification time.

[0144] 4.2 Based on the number of identification signal related information for each local device, determine whether there are multiple corresponding identification signals for each local device. If a local device has multiple corresponding identification signals, retain the identification signal with the larger signal strength of the different frequency small current signal as the valid signal; otherwise, directly use the identification signal as the valid signal.

[0145] 4.3 Determine the next level of each device as an integrated transmitting and receiving device or signal receiving device that has identified the corresponding valid signal, and obtain the operating phase when the device is a single-phase device by identifying the signal phase. The operating phase refers to phase A / phase B / phase C on the distribution network in which it operates.

[0146] Step 5: Determine whether the cascading relationships of all terminals to the distribution transformer side of the distribution area have been determined; if not, treat the integrated transmitting and receiving devices in the next level as the current level devices, and return to Step 1 for the current level devices whose next level has not been determined; continue to sort out the topology relationships; if yes, a complete topology relationship is obtained. This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement the various aspects of this disclosure.

[0147] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0148] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0149] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0150] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A distribution station topology identification system with heterogeneous frequency low current injection, comprising a master station system, a signal transmitting device, a signal receiving device, and an integrated transmitting and receiving device, characterized in that: Signal transmitting devices are installed at each terminal in the distribution transformer area, integrated transmitting and receiving devices are installed at the identification nodes in the distribution transformer area, and signal receiving devices are installed on the transformer side of the distribution transformer area. The integrated transmitting and receiving device includes a node communication module, a node main control module, a node inter-frequency signal sensing module, a node signal restoration module, and a node signal injection module. The node inter-frequency signal sensing module has multiple magnetoelectric stress coupling sensing elements. When the node communication module receives an inter-frequency signal receiving command sent by the master station system, the node main control module adjusts the identification frequency of the node inter-frequency signal sensing module to be consistent with the frequency of the injected inter-frequency small current signal. The node inter-frequency signal sensing module senses the magnetic field change caused by the inter-frequency small current signal transmitted to the node and converts it into a voltage signal, which is then output to the node signal restoration module. The node signal restoration module restores the heterogeneous frequency small current signal transmitted to the node and transmits the obtained signal identification time, signal identification phase, and restored heterogeneous frequency small current signal to the node master control module. The node master control module performs frequency domain analysis and time domain analysis on the restored heterogeneous frequency small current signal to obtain identification signal related information. The node communication module sends the identification signal related information obtained by the node master control module to the master station system. When the node communication module receives the topology identification process start command issued by the master station system, the node master control module modulates the heterogeneous frequency small current signal of the set specifications according to the start command. The node signal injection module injects the heterogeneous frequency small current signal modulated by the node master control module into the distribution network. The node communication module sends the result of the injected current to the master station system. Each terminal's signal transmitting device is considered as its own equipment. The own equipment receives instructions from the master station system and injects a set specification of low-frequency current signal into the distribution network in a time-sharing manner. The integrated transmitting and receiving device and the signal receiving device adjust the signal identification frequency point according to the frequency of the injected heterogeneous small current signal; When an integrated transmitting and receiving device or a signal receiving device identifies a small current signal at a different frequency, it sends the relevant information about the identified signal to the main station system. The master station system determines the next-level device of each local device based on the identification signal information sent by each integrated transmitting and receiving device or signal receiving device, and uses the next-level device as the local device. It continues to control the integrated transmitting and receiving devices that have not yet determined the next level to inject a small current signal of a set specification into the distribution network until the cascading relationship of all terminals to the distribution transformer side of the distribution area has been determined, and a complete distribution area topology is obtained.

2. The distribution station topology identification system with heterogeneous frequency small current injection according to claim 1, characterized in that: The signal transmitting device is set up separately at the distribution area terminal, or integrated with the power meter, acquisition terminal or branch detection equipment of the distribution area terminal.

3. The distribution station topology identification system with heterogeneous frequency small current injection according to claim 1, characterized in that: The signal transmitting device includes a terminal communication module, a terminal main control module, and a terminal signal transmitting module; After the signal transmitting device receives the topology identification process start command issued by the master station system through the terminal communication module, the terminal main control module adjusts and generates a different frequency small current signal of the set specifications according to the start command, and controls the terminal signal transmitting module to inject the different frequency small current signal into the terminal where the signal transmitting device is located. The terminal communication module sends the result of the injected current to the master station system.

4. The distribution station area topology identification system with heterogeneous frequency small current injection according to claim 1, characterized in that: The specified specifications include the modulation frequency, bit width, duty cycle, feature code, and peak current of the heterogeneous low-current signal. The feature code is a set of codes containing transmission information, which includes the ID number of the device that injects the inter-frequency small current signal and the injection time of the inter-frequency small current signal. Bit width time is the modulation transmission time of each bit in the feature code, and the modulation transmission time does not exceed 1200ms.

5. The distribution station topology identification system with heterogeneous frequency small current injection according to claim 4, characterized in that: The modulation frequency is set to 200~1000Hz, and the odd and even harmonic frequencies of the power frequency must be avoided. The peak value of the small current signal at different frequencies should not exceed 100mA.

6. The distribution station topology identification system with heterogeneous frequency small current injection according to claim 1, characterized in that: The information related to the identification signal includes the injection time of the differential frequency small current signal, the ID number of the device that injected the differential frequency small current signal, the strength of the differential frequency small current signal, the signal identification time, and the signal identification phase.

7. The distribution station topology identification system with heterogeneous frequency small current injection according to claim 1, characterized in that: The node main control module includes a node identification frequency adjustment unit, a node sampling frequency adjustment unit, a node analog-to-digital converter, a node frequency domain analysis unit, a node time domain analysis unit, a node information processing unit, and a signal modulation unit; The node identification frequency adjustment unit selects a magnetoelectric stress coupling sensing element in the node heterofrequency signal sensing module whose signal identification frequency is consistent with the frequency of the injected heterofrequency small current signal, and connects it to the node signal restoration module. The node sampling frequency adjustment unit adjusts the sampling frequency of the node analog-to-digital converter to ensure that it is not lower than 4kHz and is an integer multiple of the power frequency and the injected signal frequency. The node analog-to-digital converter samples the restored small current signal of different frequencies input from the node signal restoration module and inputs it to the node frequency domain analysis unit. The node frequency domain analysis unit performs discrete Fourier transform on the sampled signal to separate the background signal and the different frequency small current signal in the frequency domain, and records the intensity of the different frequency small current signal. The node time-domain analysis unit demodulates and decodes the separated inter-frequency small current signal in the time domain to obtain the inter-frequency small current signal injection time and the ID number of the device that injected the inter-frequency small current signal contained in the feature code of the inter-frequency small current signal. The node information processing unit combines the injection time of the inter-frequency small current signal obtained by the node time domain analysis unit, the ID number of the device injecting the inter-frequency small current signal, the strength of the inter-frequency small current signal obtained by the node frequency domain analysis unit, and the signal identification time and signal identification phase transmitted by the node signal restoration module into a record as identification signal related information, and transmits it to the node communication module. The signal modulation unit modulates a small current signal of a different frequency with a set specification according to the start command of the topology identification process, and transmits the modulated signal to the node signal injection module.

8. The distribution station topology identification system with heterogeneous frequency small current injection according to claim 7, characterized in that: The node signal restoration module records the time of receiving the voltage signal as the signal identification time; it amplifies, filters, rectifies, and regulates the received voltage signal; then, based on the relationship between the calibrated voltage output value of the magnetoelectric stress-coupled sensing element and the heterogeneous small current signal, it calculates the magnitude of the injected heterogeneous small current signal, or calculates the magnetic field strength induced by the sensing element based on the output voltage of the magnetoelectric stress-coupled sensing element, and then calculates the magnitude of the heterogeneous small current signal transmitted to the node position based on the relationship between the magnetic field strength and the magnitude of the heterogeneous small current signal, thereby restoring the heterogeneous small current signal transmitted to the node position; the initial phase of the restored heterogeneous small current signal is recorded as the signal identification phase.

9. The distribution station topology identification system with heterogeneous frequency small current injection according to claim 1 or 7, characterized in that: When multiple signal transmitting devices or integrated transmitting and receiving devices simultaneously inject small current signals of different frequencies, the node identification frequency adjustment unit selects multiple magnetoelectric stress coupling sensing elements with different identification frequencies and connects the selected sensing elements to the node signal restoration module.

10. The distribution station topology identification system with heterogeneous frequency small current injection according to claim 1, characterized in that: The signal receiving device includes a transformer-side communication module, a transformer-side main control module, a transformer-side inter-frequency signal sensing module, and a transformer-side signal restoration module. The transformer-side frequency signal sensing module has multiple magnetoelectric stress-coupled sensing elements. When the signal receiving device receives the inter-frequency signal receiving instruction sent by the main station system through the distribution transformer side communication module, the distribution transformer side main control module adjusts the identification frequency of the distribution transformer side inter-frequency signal sensing module to be consistent with the frequency of the injected inter-frequency small current signal; the distribution transformer side inter-frequency signal sensing module senses the magnetic field change caused by the inter-frequency small current signal transmitted to the distribution transformer side, and converts it into a voltage signal and outputs it to the distribution transformer side signal restoration module. The transformer-side signal restoration module restores the inter-frequency low-current signal transmitted to the transformer side and transmits the obtained signal identification time, signal identification phase, and restored inter-frequency low-current signal to the transformer-side main control module. The transformer-side main control module performs frequency domain analysis and time domain analysis on the restored inter-frequency low-current signal to obtain the inter-frequency low-current signal injection time, the ID number of the device injecting the inter-frequency low-current signal, and the inter-frequency low-current signal strength, thereby obtaining identification signal-related information. The transformer-side communication module sends the identification signal-related information obtained by the transformer-side main control module to the master station system.

11. The distribution station topology identification system with heterogeneous frequency small current injection according to claim 10, characterized in that: The transformer-side main control module includes a transformer-side identification frequency adjustment unit, a transformer-side sampling frequency adjustment unit, a transformer-side analog-to-digital converter, a transformer-side frequency domain analysis unit, a transformer-side time domain analysis unit, and a transformer-side information processing unit; The transformer-side identification frequency adjustment unit selects a magnetoelectric stress coupling sensing element in the transformer-side inter-frequency signal sensing module whose signal identification frequency is consistent with the frequency of the injected inter-frequency small current signal, and connects it to the transformer-side signal restoration module. The transformer-side sampling frequency adjustment unit adjusts the sampling frequency of the transformer-side analog-to-digital converter to ensure that it is not lower than 4kHz and is an integer multiple of the power frequency and the injected signal frequency. The transformer-side analog-to-digital converter samples the restored small-current signal of different frequencies input from the transformer-side signal restoration module and inputs it to the transformer-side frequency domain analysis unit. The frequency domain analysis unit on the distribution transformer side performs discrete Fourier transform on the sampled signal to separate the background signal and the small current signal of different frequencies in the frequency domain, and records the intensity of the small current signal of different frequencies. The distribution transformer side time domain analysis unit demodulates and decodes the separated inter-frequency small current signal in the time domain to obtain the inter-frequency small current signal injection time and the ID number of the device that injected the inter-frequency small current signal contained in the inter-frequency small current signal feature code. The transformer-side information processing unit combines the injection time of the inter-frequency small current signal obtained by the transformer-side time domain analysis unit, the ID number of the device injecting the inter-frequency small current signal, the intensity of the inter-frequency small current signal obtained by the transformer-side frequency domain analysis unit, and the signal identification time and signal identification phase transmitted by the transformer-side signal restoration module, and records them as identification signal related information, and transmits them to the transformer-side communication module.

12. The distribution station topology identification system with heterogeneous frequency small current injection according to claim 1 or 11, characterized in that: When multiple signal transmitting devices or integrated transmitting and receiving devices simultaneously inject small current signals of different frequencies, the transformer-side identification frequency adjustment unit selects multiple magnetoelectric stress coupling sensing elements with different identification frequencies and connects the selected sensing elements to the transformer-side signal restoration module.

13. A method for identifying the topological relationship of a distribution station area based on the identification system according to any one of claims 1-12 using inter-frequency small current injection, characterized in that, The method includes the following: Step 1: Set the signal transmitting device of each terminal as the device of this level; Step 2: The local equipment receives instructions from the master station system to inject a small current signal of a set specification into the distribution network in a time-sharing manner; the integrated transmitting and receiving device and the signal receiving device adjust the signal identification frequency point according to the frequency of the injected small current signal; Step 3: After receiving the heterogeneous frequency low-current signal, the integrated transmitting and receiving device or signal receiving device sends the relevant information of the identified signal to the main station system; the relevant information includes the heterogeneous frequency low-current signal injection time, the ID number of the device that injected the heterogeneous frequency low-current signal, the heterogeneous frequency low-current signal strength, the signal identification time, and the signal identification phase; Step 4: The main station system identifies the next level device based on the identification signal information sent by each integrated transmitting and receiving device or signal receiving device; Step 5: Determine whether the cascading relationship of all terminals to the distribution transformer side of the distribution area has been determined; if not, take the integrated transmitting and receiving device in the next level as the device of this level, and return the device of this level that has not determined the next level to Step 1; if yes, the complete topology relationship is obtained.

14. The method for identifying the topology of distribution substations by heterogeneous frequency small current injection according to claim 13, characterized in that: In step 4, specifically include: 4.1 The main station system determines the scope of the next level equipment for each local equipment based on the comparison results between the ID number of the device that injects the inter-frequency small current signal and the ID number of each local equipment in the relevant information of each identification signal received, and the principle that the inter-frequency small current signal injection time of the local equipment should be earlier than the signal identification time. 4.2 Determine whether there are multiple corresponding identification signals for each local device. If there are multiple corresponding identification signals for a certain local device, retain the identification signal with the larger signal strength of the different frequency small current signal as the valid signal. Otherwise, directly use the identification signal as the valid signal. 4.3 Determine that the next level of each device is an integrated transmitting and receiving device or a signal receiving device that has identified the corresponding valid signal, and obtain the working phase when the device is a single-phase device by identifying the signal phase.

15. An electronic device, comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the method for identifying the topology of distribution stations by inter-frequency small current injection according to any one of claims 13-14.

16. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements the method for identifying the topology of distribution stations by injecting small currents at different frequencies as described in any one of claims 13-14.

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