A distribution transformer area topology identification system and method

Abstract

The present invention relates to a distribution transformer area topology identification system and method. A distribution transformer area topology identification system is composed of a transformer in the area, a number of intermediate devices, and a number of terminal devices on the distribution lines in the area according to the relationship between households in the area; among them, the terminal device has a terminal topology injection module; the intermediate device has an intermediate topology receiving module and an intermediate topology injection module; the transformer in the area has a step-down topology receiving module. This system constructs a set of distribution transformer area topology identification systems. The topology injection module actively sends a current pulse signal with the device information of the device itself. This current pulse signal will sequentially pass through the intermediate devices on the line following the network hierarchy structure and be received by the topology receiving device. The intermediate device then sends a current pulse signal with the device information of the device itself, and so on. The last-stage transformer in the area receives all the topology signals, realizing automatic identification of the distribution transformer area topology structure.

Description

Technical Field

[0001] The present invention relates to the field of distribution network management, and in particular to a distribution transformer area topology identification system and method. Background Art

[0002] At present, with the increasingly strict requirements of the State Grid Corporation for the refined management of the panoramic perception of the low-voltage distribution network, how to comprehensively improve the management of low-voltage transformer areas, identify the attribution topology relationships between the transformer areas and the meter boxes, and between the branches and the meter boxes, and achieve real-time and accurate reporting of the topology structure, and realize the full connection of the relationship of "transformer-line-branch-meter box-household meter" has become an important guarantee foundation for meeting the refined management requirements of the panoramic perception of the low-voltage distribution network. However, due to technical and management problems in the existing low-voltage distribution network, the reliability of the topology relationship information cannot be guaranteed, unified digital storage cannot be achieved, and there is no unified interface for other systems and applications to further utilize, resulting in low efficiency, long cycle, and high cost in troubleshooting problems related to the faults of the line itself, such as safety fault points and abnormal line loss points. Therefore, realizing the automatic identification of the topology relationships of each node device (including transformer areas, branches, meter boxes, and household meters) in the low-voltage distribution network is the key to solving the above problems.

[0003] The patent document with the patent number ZL201910857146.0 discloses a method for identifying the topology and line impedance of a low-voltage distribution network in a transformer area, belonging to the technical field of low-voltage distribution networks. This method first adds an edge computing terminal and several electrical measurement devices in the low-voltage distribution network in the transformer area; during each topology identification of the low-voltage distribution network in the transformer area, according to the power line carrier communication relationship between the measurement device and the edge computing terminal, determine the transformer area attribution relationship of the measurement device and the phase of the communication access phase. After each measurement device is synchronized with the edge computing terminal in time, voltage and current waveform sampling are performed and uploaded to the edge computing terminal. The edge computing terminal identifies the measurement devices on the same bus and the measurement devices at the upper level of the bus based on the waveform data; after multiple topology identifications, the final topology identification result is obtained and impedance calculation is performed. The present invention has high accuracy and speed in identifying the topology and line impedance of the low-voltage distribution network, and fully utilizes the information collection ability of the intelligent devices in the low-voltage distribution network, with low equipment cost and no impact on power quality.

[0004] The patent document with the patent number ZL201910380685.X discloses a method and system for automatic identification of substation area topology, belonging to the technical field of low-voltage power distribution network. Based on determining the topological relationship between the upper and lower levels of each branch, the invention determines the inlets of each branch based on the fact that the current at the inlet end of the branch is the sum of the currents at its outlet ends, and determines the connection relationship between the inlets and outlets of different branches according to the principle that the current at the outlet end of the branch is equal to the current at the inlet end of the connected lower-level branch, thereby determining the connection relationship between each branch. The above process can effectively avoid the problems of communication crosstalk in the power frequency communication mode and the problems of insecurity and large interference in the pulse communication mode, and improve the accuracy of topology identification.

[0005] In the field of low-voltage power distribution network, the existing node device topology identification method is based on power line carrier communication. A main calculation terminal and several electrical measurement devices are added to the low-voltage power distribution network in the substation area. During each topology identification of the low-voltage power distribution network in the substation area, according to the power line carrier communication relationship between the measurement device and the main calculation terminal, the substation area belonging relationship of the measurement device and the phase of the communication access phase are determined. After each measurement device is time-synchronized with the main calculation terminal, the main calculation terminal sends a query instruction to each branch line and the terminal measurement device, and then the main calculation terminal identifies the measurement devices on the same bus and the upper-level measurement devices on the bus based on the address information returned by each branch line and the terminal measurement device. After multiple topology identifications, the final topology identification is obtained. The disadvantage of this method is that it is easily affected by the common grounding of transformers. In practical applications, the carrier signal cannot be completely isolated by the transformer, and the carrier signal can still be coupled to other transformer substations to generate cross-substation area identification crosstalk, resulting in misjudgment of identification and low accuracy.

[0006] Therefore, there are still deficiencies in the existing detection of household line relationship file information, which still need to be improved. Summary of the Invention

[0007] In view of the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a distribution substation area topology identification system and method, which can solve the problem of possible misjudgment and low accuracy when determining the topology relationship of the substation area during identification.

[0008] To achieve the above purpose, the present invention adopts the following technical solutions:

[0009] A distribution substation area topology identification system is composed of a substation area transformer, several intermediate devices, and several terminal devices on the distribution line in the substation area according to the relationship between the substation area and households; among them,

[0010] The terminal device has a terminal topology injection module; the intermediate device has an intermediate topology receiving module and an intermediate topology injection module; the substation area transformer has a step-down topology receiving module.

[0011] Preferably, in the described distribution substation area topology identification system, the terminal topology injection module and the intermediate topology injection module are the same topology injection module;

[0012] The topology injection module includes an injection zero-crossing detection unit, an injection current sampling unit, a pulse injector, and an injection manager; the injection zero-crossing detection unit, the injection current sampling unit, and the pulse injector are all connected to the same distribution line and are respectively connected to the injection manager.

[0013] Preferably, in the described distribution substation area topology identification system, the intermediate device further includes a data synthesis module; the data synthesis module is respectively connected to the intermediate topology receiving module and the intermediate topology injection module.

[0014] Preferably, in the described distribution substation area topology identification system, the intermediate topology receiving module and the transformer topology receiving module are the same topology receiving module;

[0015] The topology receiving module includes: a pulse detection unit, a listening manager, a listening zero-crossing detection unit, and a listening current sampling unit; the pulse detection unit, the listening zero-crossing detection unit, and the listening current sampling unit are respectively connected to the listening manager.

[0016] A distribution substation area topology identification method applicable to the described distribution substation area topology identification system includes the steps:

[0017] S1. The terminal device injects a terminal current pulse signal into the distribution line where it is located;

[0018] S2. The intermediate device listens to and demodulates the current pulse signal transmitted on the distribution line, and injects a new current pulse signal into the distribution line after demodulation;

[0019] S3. The substation area transformer listens to and demodulates the current pulse signal in the distribution line, and generates a distribution substation area topology relationship table.

[0020] Preferably, in the described distribution substation area topology identification method, in steps S1 and S2, each time a current pulse signal is injected, multiple current pulse signals are injected. Each step of injecting a current pulse signal includes:

[0021] S11. The injection zero-crossing detection unit detects the zero-crossing point data of the current cycle in the distribution line, and the injection current sampling unit detects the current sampling data in the distribution line once every first predetermined time. The zero-crossing point data of the cycle and the current sampling data are sent to the injection manager;

[0022] S12. After the injection manager passes a predetermined number of current sampling points, it drives the pulse injector to write a current pulse;

[0023] S13. The injection manager determines whether the current pulse signal injection is completed. If so, it stops the injection; if not, it executes step S11.

[0024] Preferably, in the distribution transformer area topology identification method, in steps S2 and S3, the steps of listening for the current pulse signal include:

[0025] S21. The pulse detection unit detects the current pulse in the distribution line. If the current pulse is detected, it sends the detection result to the listening manager.

[0026] S22. The listening manager drives the zero-crossing detection unit to detect the positive zero-crossing of the voltage signal in the distribution line, drives the listening current sampling unit to detect the current sampling data in the distribution line once every first predetermined time, and receives the positive zero-crossing data and the current sampling data.

[0027] S23. Take two current pulse signals to perform constructed wavelet calculation to obtain the signal data of the current pulse signal.

[0028] Preferably, in the distribution transformer area topology identification method, in step S23, the steps of the constructed wavelet calculation are as follows:

[0029] S231. Take multiple current cycles in the first current pulse signal as the first wavelet set, and take multiple current cycles in the second current pulse signal as the second wavelet set.

[0030] S232. Divide the frequency band with smooth current background harmonics in the low-voltage transformer area into two intervals to obtain the mapping data of each interval, the first interval mapping and the second interval mapping.

[0031] S233. Use the constructed wave formula to process to obtain the constructed wavelet set, and extract the eigenvalues of the constructed wavelet set using the Daubechies wavelet basis algorithm; the constructed wave formula is:

[0032] ψ = h1w1 + h1w2;

[0033] Where ψ is the constructed wavelet set; w1 is the first wavelet set; w2 is the second wavelet set; h1 is the first interval mapping; h1 is the second interval mapping;

[0034] S234. Determine whether the eigenvalue is valid. If so, determine the signal data of the current pulse signal; otherwise, if the current pulse signal is not detected, execute step S21.

[0035] Preferably, in the distribution transformer area topology identification method, the content of the current pulse signal injected by the intermediate device includes the demodulated data information injected by the lower-level device and the device information of this device.

[0036] Preferably, in the described distribution transformer area topology identification method, the voltage transformation topology receiving module in the area transformer is used to receive all current pulse signals in the distribution lines of this area, and is used to form the distribution transformer area topology relation table.

[0037] Compared with the prior art, the present invention provides a distribution transformer area topology identification system and method. This system constructs a set of area topology identification systems. The intermediate devices and terminal devices are located at each node position of the area lines. The area transformer is located on the incoming line side of the low-voltage area. The intermediate devices are equipped with topology injection and receiving modules, the terminal devices are equipped with topology injection modules, and the area transformers are equipped with topology receiving modules; the topology injection module actively sends a current pulse signal carrying the device information of this device, and this current pulse signal will follow the network hierarchy's vein structure and pass through the intermediate devices on the line in sequence, and is received by the topology receiving device. The intermediate device then sends a current pulse signal carrying the device information of this device, and so on. The last-level area transformer receives all the topology signals, realizing the automatic identification of the area topology structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is the structural block diagram of the distribution transformer area topology identification system provided by the present invention;

[0039] Figure 2 is the structural block diagram of the topology injection module provided by the present invention;

[0040] Figure 3 is the structural block diagram of the topology receiving module provided by the present invention;

[0041] Figure 4 is the structural block diagram of an embodiment of the distribution transformer area topology identification system provided by the present invention;

[0042] Figure 5 is the flowchart of the distribution transformer area topology identification method provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] In order to make the objectives, technical solutions and effects of the present invention clearer and more definite, the following further describes the present invention in detail with reference to the accompanying drawings and by way of examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0044] Please refer to Figures 1 - 5 , the present invention provides a distribution transformer area topology identification system, which is composed of an area transformer 1, several intermediate devices 2 and several terminal devices 3 on the distribution lines of the area according to the area household relationship; among them,

[0045] The terminal device 3 has a terminal topology injection module; the intermediate device 2 has an intermediate topology receiving module and an intermediate topology injection module; the substation area transformer 1 has a step-down topology receiving module.

[0046] Specifically, in the distribution substation area topology identification system provided by the present invention, the substation area transformer, the intermediate device, and the terminal device cooperate by each having a topology injection module and / or a topology receiving module. The specific method is not limited, as long as it can realize the cooperative use of the terminal topology injection module, the intermediate topology injection module, the intermediate topology receiving module, and the step-down topology receiving module provided in this system, so as to achieve the effect of constructing the distribution substation area topology information.

[0047] Preferably, the present invention also provides a distribution substation area topology identification method applicable to the distribution substation area topology identification system described above, which is characterized by including the steps:

[0048] S1. The terminal device 3 injects a terminal current pulse signal into the distribution line where it is located;

[0049] S2. The intermediate device 2 monitors and demodulates the current pulse signal transmitted by the distribution line, and injects a new current pulse signal into the distribution line after demodulation;

[0050] S3. The substation area transformer 1 monitors and demodulates the current pulse signal in the distribution line, and generates a distribution substation area topology relationship table.

[0051] Generally, there is one substation area transformer 1, multiple intermediate devices 2 (each level of branch boxes) in multiple intermediate devices 2, and multiple terminal devices 3 in a substation area. Among them, the intermediate device 2 is a substation area identifier, a branch box, etc., and the terminal device 3 is a meter box, etc. As for the household electricity meters, they are all installed in the meter box, and the identification of their household ownership relationship is the topology management between the power supply line and the electricity meter, which does not belong to the technical solution to be protected by the present invention. The technical solution to be protected by the present invention is mainly the attribution relationship between each level of intermediate device 2 and the terminal device 3 in the substation area, which is convenient for management. Specifically, when the distribution substation area needs to update the topology relationship table in the substation area, the terminal device 3 will start to execute step S1; therefore, before step S1, there is also step S0. The substation area transformer 1 sequentially sends a call sensing signal to each terminal device 3. Correspondingly, the terminal device 3 (such as a meter box), the intermediate device 2 (such as a branch box), and the substation area transformer 1 are all equipped with communication modules. It should be noted here that in actual application, it is common knowledge in this field that the terminal device 3, the intermediate device 2, and the substation area transformer 1 all include communication modules for data communication with each other; as for which terminal device 3 executes this method each time, it can be specifically set according to the on-site situation and is not limited.

[0052] Specifically in step S2, the intermediate devices 2 belong to different levels, that is, there is also a corresponding attribution relationship among the multiple intermediate devices 2, and all are used to monitor and demodulate the current pulse signals in the connected power distribution lines. It should be noted here that in order to prevent data from being confused, the lengths of the lower-level signals that each level of intermediate device 2 needs to monitor are different. Only when the current pulse signal transmitted by the lower-level intermediate device 2 is monitored, step S2 is executed. In step S3, the substation transformer 1 does not need to send current pulse signals, but only needs to monitor the pulse signals in the line, and manage the substation topology relationship by demodulating all received current pulses.

[0053] Please refer specifically to Figure 4 , in this embodiment, the topology structure of the power distribution substation is divided into four layers: substation transformer - branch switch box (1.A) - branch switch box (1.A.1 / 1.A.3) - meter box (1.A.1.1 / 1.A.1.2, etc.). Among them, if the electric meter is used as the terminal device 3, the topology structure in this embodiment is five layers. The first layer "transformer" is from the low-voltage outlet side of the transformer to the line layer. At the outlet side of the transformer in this layer, 1 intelligent distribution transformer terminal is allocated, which is used for monitoring the signals sent by all topologies in the entire substation, signal analysis, and automatic generation of the substation topology diagram, and the address code is "1";

[0054] The middle layer "line" is the area from the outlet side of the transformer to the inlet of the meter box. According to the structural complexity of different substations, it can be divided into one or two layers of superior-subordinate relationships. In this example, two layers of superior-subordinate relationships are taken, that is, the middle 1 layer and the middle 1.X layer. At the nodes of the middle 1 layer and the middle 1.X layer, the same branch monitoring terminals are allocated, which are used for monitoring and sending the topology signals of each node in the middle layer line, and are represented by the address codes "1.A", "1.A.1", "1.A.2", "1.A.3" respectively;

[0055] The meter box layer "meter" is the area from the inlet of the meter box to the outlet of the meter box. At the inlet side of each meter box, 1 meter box monitoring terminal is allocated, which is used for sending the topology signals of the nodes of this meter box, and the address codes are "1.A.1.1", "1.A.1.2", "1.A.3.1", "1.A.3.2", etc.;

[0056] The last layer "household" is from the outlet of each household of the meter box to the user load inlet switch, and each household is 1 end node, and the address is represented by "1.A.1.1.X";

[0057] After the equipment assignment of the entire substation is completed, the topological address signal is sent from bottom to top, such as; the address "1.A.1.1.X" of the household meter level is uploaded to the meter box monitoring terminal topology sending device in this meter box through 485. The device packages the household meter address information as a subclass of this node, generates a meter box layer package address "1.A.1.1&1.A.1.1.X...", and then injects the pulse current address signal of this package address into the line at the meter box entry point, and uploads the topological address information to the previous node of this branch. The previous node is the confluence point of this line and other lines to which the meter box terminal topology sending device belongs. In this example, it is the middle 2nd layer. The branch monitoring terminal topology sending and receiving device is installed at this point. Its main function is to monitor and collect the injection of the meter box terminal topology sending device (there are 2 here) at the lower end of the line. The pulse current address signal of this type of signal is integrated and attributed to its own address signal as a subclass to generate a branch layer packet address of “1.A.1&1.A.1.1&1.A.1.1.X…” and then the pulse current address signal of the generated branch layer packet address is injected into the branch line node through the sending module. Since there is only one current source (transformer) in the low-voltage substation, the flow direction of the current signal is unidirectional, that is, from top to bottom. In this way, the receiving devices at the same layer but different nodes will not receive signals from other nodes at the same layer. Only the upper layer can receive the signal, that is, the middle 1-layer branch monitoring terminal with the topological address “1.A” will receive the branch layer packet address “1.A.1&1.A.1.1&1.A.1.1.X…” sent by the middle 2 layers. The middle layer 1 integrates such signals and attributes them to its own address signals as a subclass, generating a branch layer packet address "1.A&1.A.1&1.A.1.1&1.A.1.1.X..." and then injects the pulse current address signal of the generated branch layer packet address into the branch line node of the middle layer 1 through the sending module. By analogy, finally, the first layer equipment, i.e., the intelligent distribution transformer terminal topology identification receiving device, monitors and receives the pulse current address signals sent by all the next-level branch terminal topology sending devices, aggregates all the address information, adds its own topology address information, and generates the first layer topology information packet address "1&1.A&1.A.1&1.A.1.1&1.A.1.1.X..." Finally, according to the recursive relationship of the information address, the complete topology map of the substation area is automatically generated and uploaded to the main station.

[0058] As a pre-selected solution, in this embodiment, the terminal topology injection module and the room topology injection module are the same topology injection module;

[0059] The topology injection module includes a zero-crossing detection unit 11 for injection, a current sampling unit 12 for injection, a pulse injector 13, and an injection manager 14; the zero-crossing detection unit 11 for injection, the current sampling unit 12 for injection, and the pulse injector 13 are all arranged on the same distribution line and are respectively connected to the injection manager 14. The zero-crossing detection unit 11 for injection, the current sampling unit 12 for injection, the pulse injector 13, and the injection manager 14 are all common components in the art; the injection manager 14 drives the zero-crossing detection unit 11 for injection, the pulse injector 13, and the current sampling unit 12 for injection to preferably work according to the steps of S11-S13. Of course, other pulse injection methods in the art can also be used to inject pulses.

[0060] Correspondingly, in the power distribution substation topology identification method provided by the present invention, in steps S1 and S2, each time a current pulse signal is injected, multiple current pulse signals are injected. Each step of injecting a current pulse signal includes:

[0061] S11. The zero-crossing detection unit 11 for injection detects the zero-crossing data of the current cycle in the distribution line. The current sampling unit 12 for injection detects the current sampling data in the distribution line at intervals of a first predetermined time. The zero-crossing data of the cycle and the current sampling data are sent to the injection manager 14;

[0062] S12. After the injection manager 14 passes a predetermined number of current sampling points, it drives the pulse injector 13 to write a current pulse;

[0063] S13. The injection manager 14 determines whether the current pulse signal injection is completed. If so, it stops the injection; if not, it executes step S11.

[0064] Specifically, the device information of this device is stored in the injection manager 14. When injection is required, the device information is converted and expressed using a current pulse signal. Specifically, current pulses are injected on multiple current cycles, and the current pulse signal is modulated. The preferred time length of each current pulse is 50 microseconds. Preferably, the current pulses are all injected on the positive half-wave of the current cycle; the first predetermined time is 1 / 18 (i.e., the current cycle is detected 360 times) milliseconds. In step S12, the predetermined number is set according to on-site requirements and the type of the zero-crossing data of the cycle. Generally, the voltage cycle of alternating current is formed in a sinusoidal state. Therefore, the types of the zero-crossing points of the cycle are divided into zero-crossing points towards the negative (i.e., after zero-crossing, the current direction is the negative half-wave of the cycle) and zero-crossing points towards the positive (i.e., after zero-crossing, the current direction is the positive half-wave of the cycle). If, in actual use, the main detection is of the zero-crossing points towards the positive, the predetermined number is preferably 165. If the main detection is of the zero-crossing points towards the negative, the predetermined number is preferably 345.

[0065] As a preferred solution, in this embodiment, the intermediate device 2 further includes a data synthesis module (not shown in the figure); the data synthesis module is respectively connected to the intermediate topology receiving module and the intermediate topology injection module. The data synthesis module is used to connect the device information of this device with the current pulse signal data sent by the received lower-level device, and a device with a data synthesis function commonly used in the art is used, without specific limitation.

[0066] Preferably, the device information lengths of the terminal device 3 and the intermediate device 2 are the same, but the lengths of the current pulse signals sent are different. The current pulse signal sent by the intermediate device 2 includes the device information of the lower-level intermediate device 2 or the terminal device 3.

[0067] As a preferred solution, in this embodiment, the intermediate topology receiving module and the transformer topology receiving module are the same topology receiving module;

[0068] The topology receiving module includes: a pulse detection unit 21, a listening manager 22, a zero-crossing detection unit 23 for listening, and a current sampling unit 24 for listening; the pulse detection unit 21, the zero-crossing detection unit 23 for listening, and the current sampling unit 24 for listening are respectively connected to the listening manager 22. The pulse detection unit 21, the listening manager 22, the zero-crossing detection unit 23 for listening, and the current sampling unit 24 for listening are all common electronic components in the art, without specific limitation. Preferably, the pulse detection unit 21 is used to detect whether there is a current pulse in the power distribution line, and when a current pulse is detected, it sends the detection result to the listening manager 22, which is a common technical means in the art and will not be elaborated; the listening manager 22 uses a commonly used MCU in the art, and the specific model and type are not limited; the zero-crossing detection unit 23 for listening is used to detect the zero-crossing point of the cycle (voltage cycle) and transmit it to the listening manager 22. The current sampling unit 24 for listening samples in the power distribution line according to the instruction of the listening manager 22, and at the same time transmits the sampling signal to the listening manager 22, and the listening manager 22 starts to count.

[0069] Correspondingly, in the topology recognition method provided by the present invention, for the listening of the current pulse signal, other methods in the art that can realize current pulse listening or detection can be used for processing. Preferably, in steps S2 and S3, the steps of listening to the current pulse signal include:

[0070] S21. The pulse detection unit 21 detects the current pulse in the power distribution line. If the current pulse is detected, it sends the detection result to the listening manager 22;

[0071] S22. The monitoring manager 22 drives the zero-crossing detection unit 23 to detect the positive zero-crossing of the voltage signal in the power distribution line, drives the monitoring current sampling unit 24 to detect the current sampling data in the power distribution line once every first predetermined time, and receives the positive zero-crossing data and the current sampling data;

[0072] S23. Take two current pulse signals to perform constructed wavelet calculation to obtain the signal data of the current pulse signal.

[0073] As a preferred solution, in this embodiment, in step S23, the steps of the constructed wavelet calculation are as follows:

[0074] S231. Take multiple current cycles in the first current pulse signal as the first wavelet set, and take multiple current cycles in the second current pulse signal as the second wavelet set;

[0075] S232. Divide the frequency band with smooth current background harmonics in the low-voltage area into two intervals to obtain the mapping data of each interval, the first interval mapping and the second interval mapping; preferably, the frequency band with smooth current background harmonics is preferably 150 - 1000 Hz;

[0076] S233. Use the constructed wave formula to process to obtain the constructed wavelet set, and extract the eigenvalues of the constructed wavelet set using the Daubechies wavelet basis algorithm; the constructed wave formula is:

[0077] ψ = h1w1 + h1w2;

[0078] Where ψ is the constructed wavelet set; w1 is the first wavelet set; w2 is the second wavelet set; h1 is the first interval mapping; h1 is the second interval mapping;

[0079] S234. Determine whether the eigenvalue is valid. If so, determine the signal data of the current pulse signal; otherwise, if no current pulse signal is detected, execute step S21.

[0080] Specifically, the Daubechies wavelet basis algorithm is a well-known algorithm in the art and will not be elaborated here. This method uses the pulse current injection signal topology recognition technology. Due to the complex and changeable on-site environment in low-voltage power distribution areas, the pulse current injection signal will be interfered by background current harmonics. The modulation and demodulation methods of the modulation signal are the key to improving the recognition accuracy. This method uses the pulse current recognition algorithm constructed by wavelet transform to extract characteristic signals from the background environment with severe harmonics, overcome the defects of Fourier transform frequency aliasing and spectral leakage, do not require the integrity of the signal, extract localized features in the time domain and frequency domain of the signal, extract amplitude-frequency information on each frequency sub-band of the incomplete target signal, and use scale stretching to obtain an adjustable "flexible window" according to the high and low signal frequencies, eliminate interference, identify some mutated and aliased signals, and improve the recognition accuracy.

[0081] Among them, the constructed wavelet set ψ uses the Daubechies wavelet basis DB4 to achieve the feature extraction of characteristic signals, and the decomposition level is 2 layers. The specific situation is as follows:

[0082] The detail coefficient d of the topology signal at the i-th decomposition scale i+1,k and the approximation coefficient c i+1,k are:

[0083]

[0084]

[0085] In the formula, h(n)c i,n+2k is the signal frequency, g(n)c i,n+2k is the signal recognition degree, and n is the amplitude-frequency information value.

[0086] After the constructed wavelet set ψ is processed using the Daubechies wavelet basis DB4, the approximate component and detail component of the constructed wavelet set ψ are obtained, and the characteristic signal is extracted by comparing the detail component with the empirical threshold. The above calculation process is a common technology in the art and is not limited and will not be elaborated.

[0087] In addition, considering the requirement of data accuracy, when injecting the current pulse signal each time, the data of the first two current cycles are only used as the monitoring threshold, so that the pulse detection unit 21 can detect the current pulse, and then further execute the current pulse signal monitoring operation S21 - S23 provided by the present invention. Of course, in this case, in the step of monitoring the current pulse signal, in step S231, it is necessary to ignore the previous one or two current cycles and then construct the first wavelet set and the second wavelet set.

[0088] It will be understood that those of ordinary skill in the art can make equivalent substitutions or changes based on the technical solutions of the present invention and its inventive concept, and all such changes or substitutions should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A distribution transformer area topology identification system, characterized in that It is composed of a substation transformer, several intermediate devices, and several terminal devices on the distribution line in the substation according to the household relationship in the substation area; among them, the terminal device has a terminal topology injection module that injects a terminal current pulse signal into the distribution line where it is located; the intermediate device has an intermediate topology receiving module and an intermediate topology injection module that listens to and demodulates the current pulse signal transmitted on the distribution line and injects a new current pulse signal into the distribution line after demodulation; the substation transformer has a step-down topology receiving module that listens to and demodulates the current pulse signal in the distribution line to generate a distribution substation topology relationship table; the intermediate device and the substation transformer are used to take the current pulses in the distribution line twice, take multiple current cycles in the first current pulse signal as the first wavelet set, take multiple current cycles in the second current pulse signal as the second wavelet set, divide the frequency band where the current background harmonics in the low-voltage substation area are smoothed into two intervals, obtain the first interval mapping and the second interval mapping of the mapping data for each interval, use the construction wave formula to process to obtain the constructed wavelet set, extract the eigenvalues of the constructed wavelet set using the Daubechies wavelet basis algorithm, and when the eigenvalues are valid, determine the signal data of the current pulse signal; The construction wave formula is: ψ = h1w1 + h2w2; Where ψ is the constructed wavelet set; w1 is the first wavelet set; w2 is the second wavelet set; h1 is the first interval mapping; h2 is the second interval mapping.

2. The distribution transformer area topology identification system according to claim 1, characterized in that, The terminal topology injection module and the intermediate topology injection module are the same topology injection module; The topology injection module includes an injection zero-crossing detection unit, an injection current sampling unit, a pulse injector, and an injection manager; the injection zero-crossing detection unit, the injection current sampling unit, and the pulse injector are all connected to the same distribution line and are respectively connected to the injection manager.

3. The distribution transformer area topology identification system according to claim 2, wherein The intermediate device further includes a data synthesis module; the data synthesis module is respectively connected to the intermediate topology receiving module and the intermediate topology injection module.

4. The distribution transformer area topology identification system according to claim 1, wherein The intermediate topology receiving module and the step-down topology receiving module are the same topology receiving module; The topology receiving module includes: a pulse detection unit, a listening manager, a listening zero-crossing detection unit, and a listening current sampling unit; The pulse detection unit, the listening zero-crossing detection unit, and the listening current sampling unit are respectively connected to the listening manager.

5. A distribution transformer area topology identification method applicable to the distribution transformer area topology identification system according to any one of claims 1-4, characterized in that, It includes the steps: S1. The terminal device injects a terminal current pulse signal into the distribution line where it is located; S2. The intermediate device listens to and demodulates the current pulse signal transmitted on the distribution line and injects a new current pulse signal into the distribution line after demodulation; S3. The substation transformer listens to and demodulates the current pulse signal in the distribution line to generate a distribution substation topology relationship table; In steps S2 and S3, the step of listening to the current pulse signal includes: S21. The pulse detection unit detects the current pulse in the distribution line, and if the current pulse is detected, it sends the detection result to the listening manager; S22. The monitoring manager drives the zero-crossing detection unit to detect the positive zero-crossing of the voltage signal in the power distribution line, drives the monitoring current sampling unit to detect the current sampling data in the power distribution line once every first predetermined time, and receives the positive zero-crossing data and the current sampling data. S23. Take two current pulse signals to perform constructed wavelet calculation to obtain the signal data of the current pulse signal. In step S23, the steps of the constructed wavelet calculation are as follows: S231. Take multiple current cycles in the first current pulse signal as the first wavelet set, and take multiple current cycles in the second current pulse signal as the second wavelet set. S232. Divide the frequency band where the current background harmonics of the low-voltage substation area are smooth into two intervals to obtain the mapping data of each interval, the first interval mapping and the second interval mapping. S233. Use the constructed wave formula to process to obtain the constructed wavelet set, and extract the eigenvalues of the constructed wavelet set using the Daubechies wavelet basis algorithm; the constructed wave formula is: ψ = h1w1 + h2w2; where ψ is the constructed wavelet set; w1 is the first wavelet set; w2 is the second wavelet set; h1 is the first interval mapping; h2 is the second interval mapping. S234. Determine whether the eigenvalues are valid. If so, determine the signal data of the current pulse signal; otherwise, if no current pulse signal is detected, execute step S21.

6. The distribution transformer area topology identification method according to claim 5, wherein, In steps S1 and S2, each time a current pulse signal is injected, multiple current pulse signals are injected. The steps of injecting a current pulse signal each time include: S11. The injection zero-crossing detection unit detects the zero-crossing data of the current cycle in the power distribution line, and the injection current sampling unit detects the current sampling data in the power distribution line once every first predetermined time. The zero-crossing data of the cycle and the current sampling data are sent to the injection manager. S12. After the injection manager passes a predetermined number of current sampling points, it drives the pulse injector to write a current pulse. S13. The injection manager determines whether the current pulse signal injection is completed. If so, stop the injection; if not, execute step S11.

7. The power distribution substation topology identification method according to claim 5, wherein The content of the current pulse signal of the intermediate device injecting the signal includes the demodulated data information injected by the lower-level device and the device information of this device.

8. The distribution transformer area topology identification method according to claim 5, characterized in that The variable voltage topology receiving module in the substation area transformer is used to receive all the current pulse signals in the power distribution line of this substation area and is used to construct the power distribution substation area topology relation table.

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