Low-voltage area complex line topology identification device, system and method

Abstract

The application provides a low-voltage area complex line topology identification device, system and method, and belongs to the technical field of power system distribution network diagnosis. The identification system adopts multiple identification devices as transmitting nodes to actively inject characteristic current into L-N loops, and when one of the identification devices is used as a transmitting node, the remaining identification devices are used as receiving nodes to collect voltage disturbance signals and current response signals of the L-N loop. The relationship between the transmitting node and the receiving node is determined based on the voltage disturbance signals and the current response signals. All the identification devices are polled, and the line topology of the low-voltage area is established according to the relationship between the nodes, so that the complex area topology identification can be accurately realized in the state of no power outage.

Description

Technical Field

[0001] This invention relates to the field of power system distribution network diagnostics technology, and in particular to a device, system and method for identifying complex line topologies in low-voltage distribution areas. Background Technology

[0002] Low-voltage distribution substations are located at the end of the power supply and consumption chain in a power system, serving as a crucial link in power supply to users. They typically include multiple nodes such as distribution transformers, low-voltage outgoing lines, branch boxes, meter boxes, and user access points, as well as branch lines connecting these nodes. For maintenance personnel, accurately understanding the connections between these nodes is essential for conducting line loss analysis, fault location, outage cause assessment, and electricity theft investigation. However, in practice, the numerous branches, large number of nodes, and complex wiring environments within the substation, along with potential user rewiring, phase changes, and meter box relocations, make it difficult for maintenance personnel to accurately grasp the electrical connections between the nodes.

[0003] Currently, the identification of low-voltage transformer area line connections mainly relies on manual verification, power outage verification, and correlation analysis based on electricity consumption data. Manual verification depends on maintenance personnel checking lines on-site, verifying meter boxes and user records, which is labor-intensive and inefficient. It is prone to missing some lines and nodes due to concealed wiring, missing cable markings, and underground wiring, sometimes making it difficult to guarantee the accuracy and completeness of the identification results. Power outage verification requires interrupting user power supply to confirm power supply relationships. While it can improve the completeness of the identification results to some extent compared to manual verification, especially for identifying hidden lines, it requires interrupting user power supply. Identification based on electricity consumption data requires correlation inference analysis based on a large amount of operational data such as voltage, current, power, and electricity consumption curves. It is highly dependent on data quality, time synchronization accuracy, load fluctuation characteristics, and sample length. Furthermore, when transformer area load changes are not significant and user loads are random, correlation characteristics are more easily weakened or interfered with, making transformer area line topology identification based on electricity consumption data difficult to implement. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a device, system, and method for identifying complex line topologies in low-voltage distribution areas. The system employs multiple identification devices that take turns acting as transmitting nodes to actively inject characteristic current into the LN circuit. While one identification device acts as the transmitting node, the remaining devices act as receiving nodes, simultaneously acquiring the current response and voltage disturbances in the LN circuit. Based on the voltage disturbance signal and the current response signal, the relationship between the transmitting and receiving nodes is determined. By polling all the identification devices and establishing the line topology map of the low-voltage distribution area according to the relationships between the nodes, the system can accurately identify the topology of complex distribution area lines without power outages.

[0005] On one hand, the present invention provides a method for identifying complex line topologies in low-voltage distribution areas, the method comprising the following steps:

[0006] S1. Deploy identification devices at each node in the low-voltage distribution area;

[0007] S2. The cloud platform sequentially designates one node as the transmitting node and the remaining nodes as receiving nodes, and sends a transmitting command to the identification device of the transmitting node;

[0008] S3. The identification device of the transmitting node periodically adds or removes the load on the node to inject a characteristic current signal into the LN circuit, and simultaneously collects the characteristic current response signal at the transmitting node. When the characteristic current response signal stabilizes, it notifies the cloud platform.

[0009] S4. After receiving the notification, the cloud platform commands all the identification devices to simultaneously collect the voltage disturbance signal and current response signal at their respective nodes, and uses the current response signal at the transmitting node as the characteristic current signal injected into the LN circuit.

[0010] S5. Determine whether there is an electrical connection between the transmitting node and each receiving node based on the voltage disturbance signal;

[0011] S6. For nodes with electrical connections, calculate the current path response coefficient between the transmitting node and the receiving node, and determine the upstream and downstream relationship between the transmitting node and the receiving node;

[0012] S7. Calculate the perturbation transfer impedance between the transmitting node and each upstream receiving node, and determine the connection topology between the transmitting node and each upstream receiving node;

[0013] S8. The cloud platform sequentially sets each identification device as a transmitting node, repeats the above steps, obtains detection data covering all nodes, and generates a low-voltage distribution area line topology map.

[0014] Furthermore, in S5, the method for determining whether there is an electrical connection between the transmitting node and each receiving node is as follows:

[0015] When the amplitude of the voltage disturbance signal at the receiving node is greater than or equal to the first threshold of the voltage disturbance signal, and the frequency and phase of the voltage disturbance signal at the receiving node are consistent with the frequency and phase of the voltage disturbance signal at the transmitting node, it is determined that there is an electrical connection between the receiving node and the transmitting node.

[0016] When the amplitude of the voltage disturbance signal at the receiving node is less than or equal to the second threshold of the voltage disturbance signal, or when the frequency and phase of the voltage disturbance signal at the receiving node are inconsistent with the frequency and phase of the voltage disturbance signal at the transmitting node, it is determined that there is no electrical connection between the receiving node and the transmitting node.

[0017] When the amplitude of the voltage disturbance signal at the receiving node is less than the first threshold of the voltage disturbance signal and greater than the second threshold of the voltage disturbance signal, the electrical connection relationship between the receiving node and the current transmitting node is confirmed when the receiving node is subsequently set as the transmitting node.

[0018] Wherein, the first threshold of the voltage disturbance signal is a preset value of 45% to 55% of the amplitude of the voltage disturbance signal at the transmitting node, and the second threshold of the voltage disturbance signal is a preset value of 5% to 15% of the amplitude of the voltage disturbance signal at the transmitting node.

[0019] Furthermore, in S6, the method for determining the upstream and downstream relationship between the transmitting node and the receiving node is as follows:

[0020] When the current path response coefficient from the transmitting node to the receiving node is greater than or equal to a first threshold of the current path response coefficient, it is determined that the receiving node is upstream of the transmitting node.

[0021] When the current path response coefficient from the transmitting node to the receiving node is less than or equal to the second threshold of the current path response coefficient, it is determined that the receiving node is located downstream of the transmitting node or is a bypass branch of the upstream node.

[0022] When the current path response coefficient from the transmitting node to the receiving node is less than the first threshold of the current path response coefficient and greater than the second threshold of the current path response coefficient, the upstream and downstream relationship between the receiving node and the current transmitting node is confirmed when the receiving node is subsequently set as the transmitting node.

[0023] The first threshold of the current path response coefficient is a preset value between 0.7 and 0.9, and the second threshold of the current path response coefficient is a preset value between 0.2 and 0.4.

[0024] Furthermore, in S7, the method for determining the connection topology between the transmitting node and each upstream receiving node is as follows:

[0025] The real part of the perturbation transfer impedance is calculated, and the receiver node corresponding to the smallest real part is determined to be the closest to the transmitter node. The receiver nodes are then sorted in order to obtain the connection topology between the transmitter node and each upstream receiver node.

[0026] Further, the perturbation transfer impedance is calculated and the perturbation transfer impedance matrix is ​​formed through the following steps:

[0027] Acquire the actual injected characteristic current signal of the identification device, which serves as the transmitting node, in the LN circuit;

[0028] The voltage disturbance signal is acquired, and the voltage disturbance signal includes the voltage signal collected by the identification device, which acts as a receiving node, when the characteristic current signal is injected.

[0029] Calculate the perturbation transfer impedance, wherein the perturbation transfer impedance is equal to the ratio of the voltage perturbation signal to the actual injected characteristic current signal;

[0030] By traversing each of the identification devices that serve as receiving nodes, a perturbation transfer impedance matrix is ​​formed between the transmitting node and each receiving node.

[0031] Further, the current path response coefficients are calculated and a current path response coefficient matrix is ​​formed through the following steps:

[0032] Acquire the current response signal of the receiving node, wherein the current response signal is the characteristic current signal collected by the characteristic current receiving circuit module of each of the identification devices serving as the receiving node;

[0033] Acquire the characteristic current signal actually injected by the identification device, which acts as the transmitting node;

[0034] Calculate the current path response coefficient, wherein the current path response coefficient is equal to the ratio of the amplitude of the current response signal to the amplitude of the actual injected characteristic current signal;

[0035] By traversing each of the identification devices that serve as receiving nodes, a current path response coefficient matrix is ​​formed between the transmitting node and each receiving node.

[0036] Further, the connection topology between the transmitting node and each upstream receiving node is determined by calculating the comprehensive score of the transmitting node and each upstream receiving node through the following steps:

[0037] Calculate the current path score based on each current path response coefficient in the current path response coefficient matrix;

[0038] The driving point impedance of the receiving node is calculated, and the impedance score is calculated based on the difference between each of the perturbation transfer impedances in the perturbation transfer impedance matrix and the driving point impedance of the corresponding receiving node. The driving point impedance is the voltage perturbation signal collected by the identification device at the receiving node divided by the current response signal collected synchronously at the receiving node.

[0039] The current path score and the impedance score are weighted and summed to obtain the comprehensive score; wherein the larger the value of the comprehensive score, the closer the transmitting node is to the upstream receiving node.

[0040] On the other hand, the present invention provides a system for identifying complex line topologies in low-voltage distribution areas, which performs the aforementioned method for identifying complex line topologies in low-voltage distribution areas. The system comprises:

[0041] Multiple identification devices are distributed and deployed in nodes within a low-voltage distribution area. Each identification device includes a characteristic current transmitting circuit module, a characteristic current receiving circuit module, a control processing module, a voltage acquisition module, and a communication module. The characteristic current transmitting circuit module, the characteristic current receiving module, and the voltage acquisition module are respectively connected to the LN loop of the distribution area and are communicatively connected to the control processing module and the communication module, respectively.

[0042] A cloud platform, wherein the cloud platform includes a task scheduling module, a data transmission module, and a topology identification module, wherein the data transmission module is communicatively connected to the communication module of each of the identification devices, and is also communicatively connected to the task scheduling module and the topology identification module, wherein the task scheduling module sequentially designates one of the identification devices as a transmitting node and the remaining identification devices as receiving nodes, and the cloud platform uses the data transmission module to send a transmission command to the identification device designated as the transmitting node;

[0043] The characteristic current transmitting circuit module of the identification device designated as the transmitting node periodically adds or removes the load to the node, the characteristic current receiving circuit module synchronously collects the characteristic current response signal, and when the characteristic current response signal stabilizes, the communication module notifies the cloud platform.

[0044] After receiving a notification from the identification device designated as the transmitting node, the cloud platform commands all the identification devices to simultaneously collect the voltage disturbance signal and current response signal at their respective nodes. Using the current response signal at the transmitting node as the characteristic current signal injected into the LN loop, the platform calculates the current path response coefficient and perturbation transfer impedance between the transmitting node and the receiving node, and determines the topological connection relationship between the transmitting node and the receiving node.

[0045] Furthermore, the identification device is configured to first acquire the background LN voltage in the uninjected state before injecting the characteristic current into the LN circuit, then inject a probe current with a small amplitude and simultaneously acquire the LN voltage and the actual injected current in the state of injecting the probe current. Based on the voltage disturbance and probe current before and after injecting the probe current, the equivalent impedance presented by the access point to the upstream power supply side is calculated. The equivalent impedance is equal to the ratio of the voltage disturbance to the probe current. The magnitude of the characteristic current injected into the LN circuit is adjusted according to the equivalent impedance.

[0046] In another aspect, the present invention provides a low-voltage distribution area complex line topology identification device for the aforementioned low-voltage distribution area complex line topology identification method. The identification device is suitable for deployment in a low-voltage distribution area and is used to inject characteristic current signals into the LN loop of the distribution area and / or collect voltage disturbance signals and current response signals in the LN loop during distribution area line topology identification. The identification device includes:

[0047] A communication module, wherein the communication module is used to receive transmission commands and reception commands from the cloud platform;

[0048] A control processing module, wherein the control processing module is communicatively connected to the communication module;

[0049] A characteristic current transmitting circuit module, wherein the characteristic current transmitting circuit module is connected to the LN circuit of the transformer area, and the characteristic current transmitting circuit module is communicatively connected to the control processing module. The control processing module is configured to control the characteristic current transmitting circuit module to inject a characteristic current into the LN circuit of the transformer area when the communication module receives a transmitting command.

[0050] A characteristic current receiving circuit module, wherein the characteristic current receiving circuit module is connected to the LN loop of the transformer area and is communicatively connected to the control processing module and the communication module respectively. The control processing module is configured to, when the communication module receives a receiving command, control the characteristic current receiving circuit module to collect the current response signal from the LN loop of the transformer area at the same time as other identification devices deployed in the same transformer area that have also received receiving commands; and

[0051] A voltage acquisition module is provided, wherein the voltage acquisition module is connected to the LN circuit of the transformer area and is communicatively connected to the control processing module and the communication module respectively. The control processing module is configured to control the voltage acquisition module to acquire voltage disturbance signals from the LN circuit of the transformer area at the same time as other identification devices deployed in the same transformer area that have received the receiving command when the communication module receives the receiving command.

[0052] The above technical solution has the following advantages or beneficial effects:

[0053] This invention actively injects characteristic currents with controllable amplitude, frequency, phase, and encoding method into the LN circuit of the transformer area through an identification device, generating an identifiable micro-disturbance response in the transformer area line. Simultaneously, the current response and LN circuit voltage disturbance are collected by other identification devices to achieve topology identification without power interruption, effectively solving the problem that the traditional power outage verification method requires power interruption.

[0054] This invention solves the problem of unstable topology judgment in existing data correlation analysis methods when the load is stable by actively injecting characteristic current into the LN circuit of the transformer area, without relying on natural load fluctuations.

[0055] This invention specifies that each identification device executes a transmission or reception command through a cloud platform, and each identification device can independently execute a transmission or reception command. Any identification device can act as a transmission node, forming a transmission-reception relationship with the other identification devices. In conjunction with the task specification of the cloud platform, multiple rounds of detection data are generated, enabling intelligent identification of line topology in multi-branch, multi-meter box, and complex line areas without relying on manual line inspection.

[0056] This invention uses the actual injected current into the LN circuit by the identification device as the transmitting node, the voltage and current response collected by the identification device as the receiving node, and the voltage collected during transmission as the basis for calculation. This can reduce misjudgments caused by sensor errors, injection amplitude deviations, and background load fluctuations, and improve the accuracy of topology identification.

[0057] This invention determines whether there is an electrical connection between nodes by using voltage disturbance signals, feeds back the upstream and downstream relationship of the line by using the current path response coefficient, and determines the electrical distance by using micro-disturbance transfer impedance, which can improve the stability of topology identification in complex field environments under complex transformer areas.

[0058] This invention selects frequencies other than 50Hz and their integer multiples as the characteristic frequency of the characteristic current injected into the LN circuit, effectively avoiding power frequency interference and harmonic pollution, and improving the signal-to-noise ratio of the target signal in complex electromagnetic environments.

[0059] Before formally injecting the characteristic current into the LN circuit, this invention first uses a small probe current to estimate the line impedance, which helps to identify abnormal wiring and high-impedance contacts in advance, and adaptively selects the injection amplitude and frequency accordingly, avoiding blind injection that could lead to a weak signal or excessive disturbance, thereby improving the success rate of a single detection. Attached Figure Description

[0060] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0061] Figure 1 This is a schematic diagram of the structure of a complex line topology identification system for low-voltage distribution areas provided in an embodiment of the present invention.

[0062] Figure 2 This is a structural block diagram of the identification device for a low-voltage distribution area complex line topology identification system provided in an embodiment of the present invention.

[0063] Figure 3 A preferred circuit diagram of the characteristic current emission circuit module of the identification device provided in the embodiments of the present invention.

[0064] Figure 4 A preferred circuit diagram of the characteristic current receiving circuit module of the identification device provided in the embodiment of the present invention.

[0065] Figure 5 This is a schematic diagram of the topology identification process of the low-voltage distribution area complex line topology identification system provided in this embodiment of the invention.

[0066] Figure 6 This is a schematic diagram illustrating the process of constructing a perturbation transfer impedance matrix in the low-voltage distribution area complex line topology identification system provided in this embodiment of the invention.

[0067] Figure 7 This is a schematic diagram illustrating the process of constructing the current path response coefficient matrix in the low-voltage distribution area complex line topology identification system provided in this embodiment of the invention.

[0068] Figure 8 This is a schematic diagram of a line for illustrating the method of identifying the topology of a transformer substation, provided as an embodiment of the present invention. Detailed Implementation

[0069] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0070] This invention provides a system for identifying the complex line topology in low-voltage distribution areas. The system is deployed within a low-voltage distribution area and employs multiple identification devices that take turns acting as transmitting nodes to actively inject characteristic current into the LN circuit. While one of the identification devices acts as a transmitting node, the remaining devices act as receiving nodes, simultaneously acquiring the current response and voltage disturbances in the LN circuit. Based on the voltage disturbance signal and the current response signal, the relationship between the transmitting and receiving nodes is determined. All identification devices are polled, and a line topology map of the low-voltage distribution area is established according to the relationships between the nodes, enabling topology identification of complex distribution area lines without power outages.

[0071] Specifically, refer to Figures 1 to 4 The low-voltage distribution area complex line topology identification system includes multiple identification devices and a cloud platform. The identification devices are distributed throughout the low-voltage distribution area, for example, deployed at distribution boxes, branch boxes, user access points, and low-voltage line branch nodes to form multiple detection nodes within the low-voltage distribution area. Each identification device includes a power supply module, a characteristic current transmitting circuit module, a characteristic current receiving circuit module, a control processing module, a voltage acquisition module, and a communication module. The characteristic current transmitting circuit module, the characteristic current receiving circuit module, and the voltage acquisition module are respectively connected to the LN circuit of the distribution area and are communicatively connected to the control processing module and the communication module, respectively. The cloud platform includes a task scheduling module, a data transmission module, and a topology management module. The low-voltage identification module includes a data transmission module communicatively connected to the communication modules of each identification device, and also communicatively connected to the task scheduling module and the topology identification module. The task scheduling module designates one of the identification devices as a transmitting node and the remaining identification devices as receiving nodes. The data transmission module sends a transmitting command to the identification device designated as the transmitting node and a receiving command to the remaining identification devices. The identification device designated as the transmitting node actively injects a characteristic current into the LN circuit. Each identification device designated as the receiving node synchronously collects the current response and voltage disturbance of the LN circuit and uploads them to the cloud platform. The topology identification module performs calculations based on the data uploaded by each identification device to identify the topology of the low-voltage distribution area.

[0072] Preferably, the transmission command and the reception command include one or more of the following parameters: frequency, amplitude, synchronous acquisition time, or voltage disturbance amplitude limiting parameter of the characteristic current.

[0073] In a three-phase four-wire low-voltage distribution area, the LN circuit can be an AN circuit, a BN circuit, or a CN circuit. The cloud platform can first determine the phase grouping of the identification devices based on the phase of the power frequency voltage, the zero-crossing time, or the characteristic current response collected by each identification device, and then perform topology identification within the same phase group. For multi-phase access users or multi-phase meter boxes, the cloud platform calculates the corresponding comprehensive score for each, and merges the results based on the consistency of the direct upstream nodes of each phase to form the topology attribution of the corresponding user or meter box.

[0074] It is worth mentioning that the low-voltage distribution area complex line topology identification system actively injects characteristic currents with controllable amplitude, frequency, phase, and encoding method into the distribution area LN circuit through the identification device designated as the transmitting node, generating identifiable micro-perturbation responses in the distribution area line. The current response and LN voltage disturbance are synchronously collected by each identification device designated as the receiving node, and topology identification is carried out without power interruption, effectively solving the problem that the traditional power outage verification method requires power interruption.

[0075] Furthermore, by actively injecting characteristic current into the LN circuit of the distribution area, without relying on natural load fluctuations, the problem of unstable topology judgment in existing data correlation analysis methods when the load is stable is solved, which is conducive to improving the topology identification accuracy of the complex line topology identification system in low-voltage distribution areas.

[0076] Specifically, each of the identification devices can independently execute transmission or reception commands. Any one of the identification devices can act as a transmission node, forming a transmission-reception relationship with the other identification devices. In conjunction with the task commands of the cloud platform, multiple rounds of detection data are generated, enabling line topology identification of multi-branch, multi-meter box, and complex line areas without relying on manual line inspection.

[0077] For details, please refer to Figure 2 and Figure 3The characteristic current emission circuit module of the identification device is connected between the phase line L and the neutral line N of the low-voltage zone to inject a characteristic current with controllable amplitude and frequency into the LN circuit. The characteristic current emission circuit module includes an isolation unit, a driving unit, a sampling feedback unit, and a protection unit. The isolation unit includes an optocoupler E2. The driving unit includes an NPN transistor V7, a PNP transistor V10, and a MOSFET transistor DV8. The base of the NPN transistor V7 is connected in series with the current-limiting resistor R30. The base and emitter of the PNP transistor V10 are respectively connected to the two ends of the resistor R33. The protection unit includes a diode V11, a current-limiting resistor R29, a resistor R32, a resistor R34, and a Zener diode V12 connected in parallel with the resistor R34. One end of the diode V11 is connected to one end of the current-limiting resistor R29 to form a structure in series between the diode V11 and the current-limiting resistor R29. One end of the resistor R32 is connected to the other end of the diode V11, and the other end of the resistor R32 is connected to the other end of the current-limiting resistor R29. To improve the accuracy of the sampling signal, the digital ground (GND) and signal ground (SGND) are designed separately. Capacitors C15 and C14 are filter capacitors, preferably 0.1uF. The positive power supply VCC is preferably DC 30V, and the positive terminal VB+ is the positive terminal of the DC output after rectification of the phase line L and neutral line N of the circuit under test. The negative terminal of the rectified DC output is connected to the signal ground (SGND) through a ferrite bead. The sampling feedback unit acquires the voltage signal across resistor R42 through the microprocessor's AD circuit. The ferrite bead is selected based on the high-frequency interference limitation of the digital ground and signal ground.

[0078] Preferably, resistor R31 has a resistance of 200 ohms and an accuracy of 5%; capacitors C15 and C14 both have a capacitance of 0.1uF and a voltage rating of 50V; optocoupler E2 is an EL816S1 model optocoupler; resistors R30 and R33 have resistances of 2000 ohms and 2700 ohms respectively, both with an accuracy of 5%; diode V11 is a 1N4148W; resistors R29, R32, and R34 have resistances of 5.1 ohms, 51 ohms, and 10000 ohms respectively, all with an accuracy of 5%; Zener diode V12 is an LBZT52C15T1G; MOSFET transistor DV8 is a BL3N150; resistor R51 has a resistance of 340 ohms and an accuracy of 1%; resistor R42 has a resistance of 20 ohms and an accuracy of 1%. Resistor R51 can also be replaced by a potentiometer. The maximum resistance of the potentiometer is preferably 1000 ohms with an accuracy of 1%. The preset value of the potentiometer is 340 ohms.

[0079] It is worth mentioning that the sampling feedback unit includes a resistor R42, a sampling amplification circuit, and an error amplification circuit. The voltage across the resistor R42 is proportional to the actual injected current. The sampling amplification circuit converts this voltage into a current feedback signal through a microprocessor. This current feedback signal is compared with a preset characteristic current injected into the LN circuit. The magnitude of the injected current is adjusted by the resistance value of the resistor R51, thereby forming a closed-loop control of the characteristic current injected into the LN circuit. The microprocessor in the control processing module generates a single-frequency or multi-frequency PWM signal according to the preset strategy of the identification device or the detection task instruction issued by the cloud platform. The PWM signal is isolated and amplified to drive a MOSFET to periodically add or remove load to the DC power supply. The DC power supply is the rectified power supply of the LN circuit, and the load is preferably a resistive load.

[0080] Specifically, the instantaneous current when the characteristic current transmitting circuit module injects the characteristic current into the LN circuit... A sinusoidal characteristic current with controllable amplitude, frequency, and phase is injected into the LN circuit of the transformer area as the active excitation source for topology identification. Wherein, the... This is the line reference current; The amplitude of the characteristic current is generated by the microprocessor of the identification device according to the detection task; The characteristic frequency is, and the characteristic frequency is The frequency should not be a positive integer multiple of 50Hz, preferably 713Hz, 833.3Hz, 915Hz, 1231Hz or 1477Hz, in order to effectively avoid power frequency interference and harmonic pollution and improve the signal-to-noise ratio of the target signal in complex electromagnetic environments. It is a phase control quantity, determined by the microprocessor's clock synchronization interface or through the cloud platform's synchronization clock.

[0081] It is worth mentioning that the identification device is configured to first acquire the background LN voltage phasor in the uninjected state before injecting the characteristic current into the LN circuit, then inject a probe current with a small amplitude and simultaneously acquire the LN voltage signal and the actual injected current signal under the probe current injection state. Based on the voltage disturbance signal and the probe current signal before and after the probe current injection, the equivalent impedance presented by the access point to the upstream power supply side is calculated. It is equal to the ratio of the voltage disturbance signal to the probed current signal, that is:

[0082]

[0083] in, For the detection frequency, 713Hz, 833.3Hz, 915Hz, 1231Hz or 1477Hz are preferred; To detect the LN voltage disturbance signal at the detection frequency; The actual current signal being detected is the alternating current after filtering out the DC and harmonic components of the current flowing through resistor R42. The frequency of the alternating current is the same as the detection frequency. The negative sign indicates that the voltage drop at the transmitting node is caused when additional current is absorbed. By pre-detecting the line impedance, it is helpful to identify abnormal wiring and high-impedance contacts in advance, and to adaptively select the amplitude and frequency of the injection accordingly, avoiding blind injection that would result in a weak signal or excessive disturbance, thereby improving the success rate of a single detection.

[0084] In implementation of this invention, the peak value of the characteristic current does not exceed 0.6A, the frequency range of the injected current is from 700Hz to 1500Hz, and the relative voltage variation limit at the node is ≤2.0%, so as to meet the voltage fluctuation requirements of the power grid for the common contact.

[0085] Further, refer to Figure 2 and Figure 4 The characteristic current receiving circuit module of the identification device is connected between the phase line L and the neutral line N of the low-voltage distribution area to collect the current response signal in the branch of the node where it is located. The characteristic current receiving circuit module includes a current sensing unit, a protection unit, a signal conditioning unit, a filtering unit, a signal amplifier, and an ADC sampling unit. The current response signal is first sensed by the current sensing unit, and then passes through the protection unit, the signal conditioning unit, the filtering unit, and the signal amplifier in sequence. After being sampled by the ADC, it enters the microprocessor.

[0086] The current sensing unit is used to acquire the characteristic current signal in the LN circuit. It can be one or more of an open-type, Hall-effect, or Rogowski coil current transformer and a shunt sampler, with an open-type current transformer being preferred as it can be easily clamped onto the LN circuit of the branch under test. The protection unit uses a bidirectional Zener diode for overvoltage protection and preferably a resistor R. lim Current limiting protection is provided; the signal conditioning unit is connected between the protection unit and the filtering unit, and is used to condition the signal output by the protection unit. In this embodiment, a resistor R is selected. load With capacitor C intThe circuit comprises an RC signal conditioning circuit; the filtering unit includes one or more of an anti-aliasing low-pass filter, a band-pass filter, and a power frequency suppression filter, used to suppress the power frequency fundamental wave, high-power load fluctuations, and high-frequency noise, wherein the band-pass frequency of the band-pass filter is preferably 700~1500Hz; the signal amplifier is selected as a programmable signal amplifier; the ADC sampling preferably uses a 16-bit sampling precision ADC device, and the ADC sampling is used to enable each of the identification devices designated as receiving nodes to sample synchronously under a unified time reference, wherein the synchronization method includes one or more of Beidou time synchronization, network time synchronization, and cloud platform time synchronization correction, and the synchronization error during synchronization is preferably less than 1 / 10 of a target frequency period, for example, less than 109 microseconds at a frequency of 915Hz.

[0087] The identification device extracts characteristic frequencies from the acquired current and voltage signals based on the sampling frequency of the configured ADC device. The sampling frequency can be 8kHz, 12.8kHz, 16kHz, or 20kHz, and the single detection duration can be 0.5 to 3 seconds. In this invention, synchronous detection or discrete Fourier transform extraction is used to obtain the phasor at the target frequency. For example, for the receiving node... sampling sequence Target frequency The complex phase at that point can be expressed as:

[0088]

[0089] in, For nodes At the target frequency The extracted voltage or current complex phase at that point is the ADC sampling sequence for that node. For nodes No. Voltage or current sampled values ​​at each sampling point The number of sampling points within the sampling window depends on the microprocessor's detection duration and sampling frequency. For ADC sampling frequency, For the first Each target feature frequency, It is the imaginary unit.

[0090] Furthermore, the voltage acquisition module of the identification device acquires the voltage disturbance signal of its local node. In a specific implementation, the identification device also includes a storage module that stores corresponding codes and data; the communication module communicates with the cloud platform to obtain task instructions and upload data, and the communication module can be one or more of a 4G / 5G communication module, a LoRa module, and a power line communication module.

[0091] Further, refer to Figures 1 to 8 In actual operation, each identification device executes a transmit or receive command according to the cloud platform's specifications. The topology identification module calculates the perturbation transfer impedance between the identification devices acting as transmitting and receiving nodes based on the voltage disturbance signals collected by each identification device acting as a receiving node and the actual characteristic current signal injected into the LN circuit by the identification device acting as a transmitting node. It then iterates through all identification devices acting as receiving nodes to form a perturbation transfer impedance matrix. The topology identification module calculates the current path response coefficient based on the current response signals collected by each identification device acting as a receiving node and the actual characteristic current signal injected into the LN circuit by the identification device acting as a transmitting node. It then iterates through all identification devices acting as receiving nodes to form a current path response coefficient matrix. After completing one round of detection, the task scheduling module sequentially designates other identification devices as transmitting nodes until detection data covering all nodes is obtained. The topology identification module generates a transformer area line topology map based on the perturbation transfer impedance matrix and the current path response coefficient matrix.

[0092] In detail, corresponding to Figure 6 The topology identification module calculates the perturbation transfer impedance and forms the perturbation transfer impedance matrix through the following steps:

[0093] Acquire as a launch node The identification device injects a characteristic current signal into the LN circuit. ;

[0094] The voltage disturbance signal is acquired, and the voltage disturbance signal is preferably used as a receiving node. The voltage acquisition module of the identification device acquires the voltage disturbance signal when the transmitting node injects current into the LN circuit. The voltage disturbance signal has been filtered to remove the power frequency background signal and is denoted as... ,in For the first Each characteristic frequency is determined by the task scheduling module of the cloud platform;

[0095] Calculate the perturbation transfer impedance, wherein the perturbation transfer impedance For the launch node Transmitting and receiving nodes The complex transfer impedance during reception is equal to the ratio of the voltage disturbance signal to the actual injected characteristic current signal, i.e.

[0096]

[0097] By traversing each of the identification devices acting as receiving nodes, a perturbation transfer impedance matrix is ​​formed between the transmitting node and each receiving node, corresponding to the transmitting node. Take in sequence to At that time, the cloud platform obtained perturbation transfer impedance matrix ,in For nodes The driving point perturbation impedance.

[0098] Preferably, the voltage disturbance signal For the launch node When transmitting characteristic current, the receiving node In frequency The voltage perturbation phasor at LN.

[0099] It is worth mentioning that, if multiple characteristic frequencies are used, the cloud platform can also calculate the weighted transfer impedance, as shown in the formula:

[0100]

[0101] in, For launch node To the receiving node Multi-frequency weighted perturbation transfer impedance; For the first The weight of each frequency is the voltage disturbance signal-to-noise ratio at that frequency. It is a single-frequency transfer impedance.

[0102] Specifically, if the line parameters remain approximately constant during the detection period and the identification device collects data synchronously, then if the receiving node... Located at the launch node On the upstream path, then near .in, For launch node To the receiving node The mode of the perturbation transfer impedance, For receiving nodes The driving point impedance is the magnitude of the impedance at the receiving node. The driving point impedance is the voltage disturbance signal acquired by the voltage acquisition module of the identification device at the receiving node when current is injected into the LN circuit at the transmitting node, divided by the current response signal synchronously acquired by the identification device at the receiving node. Both the voltage disturbance signal and the current response signal have been filtered to remove power frequency background signals. Therefore, by comparing the magnitude of the transfer impedance and the driving point impedance, this invention can determine the upstream and downstream relationship between nodes, is unaffected by load fluctuations, and has strong anti-interference capability.

[0103] Furthermore, corresponding to Figure 7 The topology identification module calculates the current path response coefficients and forms a current path response coefficient matrix through the following steps:

[0104] Get receiving node Current response signal Preferred method is to use a receiving node. The characteristic current signal obtained by the characteristic current receiving circuit module of the identification device is acquired and processed, and the characteristic current signal is filtered out of the power frequency current signal of the LN circuit.

[0105] Obtain the launch node The identification device actually injects a characteristic current signal into the LN circuit through its characteristic current transmitting circuit module. The characteristic current signal is preferably the current response signal of the LN circuit measured by its characteristic current receiving circuit module, and the current response signal has been filtered out of the power frequency background.

[0106] Calculate the current path response coefficient, wherein the current path response coefficient Equal to receiving node The identification device obtains the amplitude of the current response signal and the transmitting node through its characteristic current receiving circuit module. The ratio of the amplitude of the characteristic current signal actually injected by the identification device through the characteristic current transmitting circuit module, i.e.:

[0107]

[0108] By traversing each of the identification devices that serve as receiving nodes, a current path response coefficient matrix is ​​formed between the transmitting node and each receiving node.

[0109] Preferably, in the case of multiple frequencies, the topology identification module uses the current response signal-to-noise ratio or its normalized value as weights to perform a weighted average of the current path response coefficients at each frequency:

[0110]

[0111] in, For nodes With nodes Multi-frequency weighted current path response; For the first The weights of each frequency are preferably selected based on the current response signal-to-noise ratio. ; This represents the single-frequency current path response coefficient.

[0112] by Figure 8 Taking this as an example, the method for identifying complex line topologies in low-voltage distribution areas is specifically explained, including the following steps:

[0113] S1. Deploy the identification device at nodes A1, A2, A3, M, B1, B2, C1, C2, D1, D2, E1, E2;

[0114] S2. The cloud platform designates node M as the transmitting node and other nodes as receiving nodes, and sends a transmission command to the identification device of the transmitting node;

[0115] S3. The characteristic current transmission circuit module of the identification device of the transmitting node M periodically adds or removes the load to the node M to inject a characteristic current signal into the LN circuit, and simultaneously collects the characteristic current response signal at the transmitting node M. After the characteristic current response signal of the transmitting node M stabilizes, the identification device of the node M notifies the cloud platform.

[0116] S4. After receiving the notification, the cloud platform commands all identification devices to simultaneously collect the voltage disturbance signal and current response signal at their respective nodes, and uses the current response signal at the transmitting node as the characteristic current signal injected into the LN circuit.

[0117] S5. Determine whether there is an electrical connection between the transmitting node M and each receiving node based on the voltage disturbance signal, as follows:

[0118] When the amplitude of the voltage disturbance signal at the receiving node is greater than or equal to the first threshold of the voltage disturbance signal, and the frequency and phase of the voltage disturbance signal at the receiving node are consistent with the frequency and phase of the voltage disturbance signal at the transmitting node M, it is determined that the receiving node and the transmitting node M have an electrical connection. When the amplitude of the voltage disturbance signal at the receiving node is less than or equal to the second threshold of the voltage disturbance signal, or the frequency and phase of the voltage disturbance signal at the receiving node are inconsistent with the frequency and phase of the voltage disturbance signal at the transmitting node M, it is determined that the receiving node and the transmitting node do not have an electrical connection. When the amplitude of the voltage disturbance signal at the receiving node is less than the first threshold of the voltage disturbance signal and greater than the second threshold of the voltage disturbance signal, the electrical connection is confirmed when the receiving node is subsequently set as a transmitting node. The first threshold of the voltage disturbance signal is a preset value between 45% and 55% of the amplitude of the voltage disturbance signal at the transmitting node M, preferably 50%. The second threshold of the voltage disturbance signal is a preset value between 5% and 15% of the amplitude of the voltage disturbance signal at the transmitting node M, preferably 10%.

[0119] S6. For nodes with electrical connections, calculate the current path response coefficient between the transmitting node M and the receiving node to determine the upstream and downstream relationship between them. The method is as follows:

[0120] Calculate the current path response coefficient of the lines from transmitting node M to each receiving node. When the current path response coefficient from transmitting node M to the receiving node is greater than or equal to a first threshold, the receiving node is determined to be upstream of transmitting node M. When the current path response coefficient from transmitting node M to the receiving node is less than or equal to a second threshold, the receiving node is determined to be downstream of transmitting node M or a bypass branch of the upstream node. When the current path response coefficient from transmitting node M to the receiving node is less than the first threshold and greater than the second threshold, the connection relationship is confirmed when the receiving node is subsequently set as a transmitting node. The first threshold of the current path response coefficient is a preset value between 0.7 and 0.9, preferably 0.8, and the second threshold of the current path response coefficient is a preset value between 0.2 and 0.4, preferably 0.3.

[0121] S7. Calculate the perturbation transfer impedance between transmitting node M and each upstream receiving node, and determine the connection topology between transmitting node M and each upstream receiving node, as follows:

[0122] Calculate the perturbation transfer impedance between the transmitting node M and each upstream receiving node, and extract the real part of the perturbation transfer impedance. The receiving node with the largest real part is determined to be the farthest from the transmitting node; the receiving node with the smallest real part is determined to be the closest to the transmitting node M. The receiving nodes corresponding to the real parts of the other perturbation transfer impedances are then ordered sequentially. This yields the connection topology between the transmitting node M and each upstream receiving node.

[0123] Specifically, with Figure 8 For example, calculate the perturbation transfer impedance between transmitting node M and receiving nodes A3, A2, and A1, and take their real parts respectively. If the order of magnitude is as follows:

[0124]

[0125] Therefore, we can conclude that receiving node A3 is closest to transmitting node M, receiving node A2 is next, and receiving node A1 is the farthest.

[0126] in, These represent the real parts of the corresponding perturbation transfer impedances.

[0127] S8. The cloud platform sequentially sets each identification device as a transmitting node, repeats the above steps, obtains detection data covering all nodes, and generates a low-voltage distribution area line topology map.

[0128] Furthermore, the topology identification module calculates the comprehensive score of the transmitting node and the upstream receiving node through the following steps:

[0129] Calculate the current path score based on each current path response coefficient in the current path response coefficient matrix;

[0130] The driving point impedance of the receiving node is calculated, and the impedance score is calculated based on the difference between each of the perturbation transfer impedances in the perturbation transfer impedance matrix and the driving point impedance of the corresponding receiving node. The driving point impedance is the voltage perturbation signal collected by the identification device at the receiving node divided by the current response signal collected synchronously at the receiving node.

[0131] The current path score and the impedance score are weighted and summed to obtain the comprehensive score.

[0132] In detail, the launch node With receiving node The current path score is The calculation formula is as follows:

[0133]

[0134] in, Indicates will Limited to between 0 and 1.

[0135] Furthermore, launch nodes To the receiving node Perturbation transfer impedance and receiving node The difference between the driving point impedances is:

[0136]

[0137] Furthermore, the impedance scoring The calculation formula is as follows:

[0138]

[0139] in, To minimize impedance measurement uncertainty, a multi-frequency measurement standard deviation is preferred.

[0140] Furthermore, when the signal-to-noise ratio of the current response signal of the transmitting node is less than 10 dB, a comprehensive score is preferably used to determine the distance relationship between the transmitting node and the upstream node. The comprehensive score... The calculation formula is as follows:

[0141]

[0142] in, When the signal-to-noise ratio of the current response signal of the transmitting node is less than 10dB and greater than or equal to 6dB, Take 0.6; when the signal-to-noise ratio of the current response signal of the transmitting node is less than 6dB and greater than or equal to 3dB, Take 0.5; when the signal-to-noise ratio of the current response signal of the transmitting node is less than 3dB, Take 0.4.

[0143] It is worth mentioning that when the signal-to-noise ratio of the current response signal of the transmitting node is greater than or equal to 10dB, a comprehensive score can also be used to determine the distance relationship between the transmitting node and the upstream node. The weight is set to 0.9, with the current path score being the primary factor in the judgment result.

[0144] This invention calculates a comprehensive score through current path scoring and impedance scoring, avoiding misjudgments caused by a single physical quantity in complex field environments, and thus improving the accuracy of topology identification. Once these parameters are set, they must not be changed during the topology testing of the upstream lines of a transmitting node.

[0145] It's worth noting that a higher overall score indicates a closer distance between the transmitting node and the upstream receiving node. Figure 8 For example, when As the launch node, They are respectively The upstream receiving node calculates the comprehensive score of each node in turn, and obtains:

[0146]

[0147] In summary, the low-voltage distribution area complex line topology identification system determines the existence of electrical connections and electrical distances between nodes through the perturbation transfer impedance matrix and determines upstream and downstream relationships through the current path response coefficient matrix. Compared with relying solely on the presence or absence of current response or solely on voltage disturbances, it can reduce misjudgments caused by background harmonics, parasitic coupling, sensor installation errors, and measurement noise, improve the accuracy and stability of topology identification in complex low-voltage distribution area environments, and achieve accurate topology identification of complex lines in low-voltage distribution areas.

[0148] It is worth mentioning that the preferred criterion for determining the stability of the characteristic current response signal of the transmitting node is as follows:

[0149] The first and second tests are spaced at least ten characteristic current signal cycles apart. The absolute value of the difference between the amplitudes of the characteristic current response signals from the two consecutive tests is calculated. If the absolute value does not exceed 2% of the amplitude of the characteristic current in the first test, the characteristic current response signal of the transmitting node is considered stable; otherwise, it is considered unstable and further testing is required.

[0150] The amplitudes of the characteristic current response signal, voltage disturbance signal, and characteristic current signal actually injected into the LN circuit involved in this invention are all effective values ​​of the signal amplitude, and the signals are sine or cosine signals.

[0151] It is understandable that after polling all the identification devices, if there are still cases where the voltage disturbance signal amplitude at the receiving node is less than a first threshold and greater than a second threshold, or the current path response coefficient from the transmitting node to the receiving node is less than a first threshold and greater than a second threshold, then the relationship between the nodes is determined to be abnormal. In this case, a supplementary test task can be issued, which includes changing the characteristic frequency, extending the sampling time, adjusting the injected current amplitude, or changing the encoding sequence. If the abnormality persists after the supplementary test, an anomaly alert is output, and maintenance personnel manually check the connection relationship between the nodes. Optionally, in some embodiments, when an abnormal relationship between nodes is determined to be abnormal, an anomaly alert can also be directly output, and maintenance personnel can manually check the connection relationship.

[0152] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for identifying complex line topologies in low-voltage distribution areas, characterized in that, The method includes the following steps: S1. Deploy identification devices at each node in the low-voltage distribution area; S2. The cloud platform sequentially designates one node as the transmitting node and the remaining nodes as receiving nodes, and sends a transmitting command to the identification device of the transmitting node; S3. The identification device of the transmitting node periodically adds or removes the load on the node to inject a characteristic current signal into the LN circuit, and simultaneously collects the characteristic current response signal at the transmitting node. When the characteristic current response signal stabilizes, it notifies the cloud platform. S4. After receiving the notification, the cloud platform commands all the identification devices to simultaneously collect the voltage disturbance signal and current response signal at their respective nodes, and uses the current response signal at the transmitting node as the characteristic current signal injected into the LN circuit. S5. Determine whether there is an electrical connection between the transmitting node and each receiving node based on the voltage disturbance signal; S6. For nodes with electrical connections, calculate the current path response coefficient between the transmitting node and the receiving node, and determine the upstream and downstream relationship between the transmitting node and the receiving node; S7. Calculate the perturbation transfer impedance between the transmitting node and each upstream receiving node, and determine the connection topology between the transmitting node and each upstream receiving node; S8. The cloud platform sequentially sets each identification device as a transmitting node, repeats the above steps, obtains detection data covering all nodes, and generates a low-voltage distribution area line topology map.

2. The method for identifying complex line topologies in low-voltage distribution areas according to claim 1, characterized in that, In S5, the method for determining whether there is an electrical connection between the transmitting node and each receiving node is as follows: When the amplitude of the voltage disturbance signal at the receiving node is greater than or equal to the first threshold of the voltage disturbance signal, and the frequency and phase of the voltage disturbance signal at the receiving node are consistent with the frequency and phase of the voltage disturbance signal at the transmitting node, it is determined that there is an electrical connection between the receiving node and the transmitting node. When the amplitude of the voltage disturbance signal at the receiving node is less than or equal to the second threshold of the voltage disturbance signal, or when the frequency and phase of the voltage disturbance signal at the receiving node are inconsistent with the frequency and phase of the voltage disturbance signal at the transmitting node, it is determined that there is no electrical connection between the receiving node and the transmitting node. When the amplitude of the voltage disturbance signal at the receiving node is less than the first threshold of the voltage disturbance signal and greater than the second threshold of the voltage disturbance signal, the electrical connection relationship between the receiving node and the current transmitting node is confirmed when the receiving node is subsequently set as the transmitting node. Wherein, the first threshold of the voltage disturbance signal is a preset value of 45% to 55% of the amplitude of the voltage disturbance signal at the transmitting node, and the second threshold of the voltage disturbance signal is a preset value of 5% to 15% of the amplitude of the voltage disturbance signal at the transmitting node.

3. The method for identifying complex line topologies in low-voltage distribution areas according to claim 2, characterized in that, In S6, the method for determining the upstream and downstream relationship between the transmitting node and the receiving node is as follows: When the current path response coefficient from the transmitting node to the receiving node is greater than or equal to a first threshold of the current path response coefficient, it is determined that the receiving node is upstream of the transmitting node. When the current path response coefficient from the transmitting node to the receiving node is less than or equal to the second threshold of the current path response coefficient, it is determined that the receiving node is located downstream of the transmitting node or is a bypass branch of the upstream node. When the current path response coefficient from the transmitting node to the receiving node is less than the first threshold of the current path response coefficient and greater than the second threshold of the current path response coefficient, the upstream and downstream relationship between the receiving node and the current transmitting node is confirmed when the receiving node is subsequently set as the transmitting node. The first threshold of the current path response coefficient is a preset value between 0.7 and 0.9, and the second threshold of the current path response coefficient is a preset value between 0.2 and 0.

4.

4. The method for identifying complex line topologies in low-voltage distribution areas according to claim 3, characterized in that, In S7, the method for determining the connection topology between the transmitting node and each upstream receiving node is as follows: The real part of the perturbation transfer impedance is calculated, and the receiver node corresponding to the smallest real part is determined to be the closest to the transmitter node. The receiver nodes are then sorted in order to obtain the connection topology between the transmitter node and each upstream receiver node.

5. The method for identifying complex line topologies in low-voltage distribution areas according to claim 1, characterized in that, The perturbation transfer impedance is calculated and the perturbation transfer impedance matrix is ​​formed by the following steps: Acquire the actual injected characteristic current signal of the identification device, which serves as the transmitting node, in the LN circuit; The voltage disturbance signal is acquired, and the voltage disturbance signal includes the voltage signal collected by the identification device, which acts as a receiving node, when the characteristic current signal is injected. Calculate the perturbation transfer impedance, wherein the perturbation transfer impedance is equal to the ratio of the voltage perturbation signal to the actual injected characteristic current signal; By traversing each of the identification devices that serve as receiving nodes, a perturbation transfer impedance matrix is ​​formed between the transmitting node and each receiving node.

6. The method for identifying complex line topologies in low-voltage distribution areas according to claim 5, characterized in that, The current path response coefficients are calculated and a current path response coefficient matrix is ​​formed by the following steps: Acquire the current response signal of the receiving node, wherein the current response signal is the characteristic current signal collected by the characteristic current receiving circuit module of each of the identification devices serving as the receiving node; Acquire the characteristic current signal actually injected by the identification device, which acts as the transmitting node; Calculate the current path response coefficient, wherein the current path response coefficient is equal to the ratio of the amplitude of the current response signal to the amplitude of the actual injected characteristic current signal; By traversing each of the identification devices that serve as receiving nodes, a current path response coefficient matrix is ​​formed between the transmitting node and each receiving node.

7. The method for identifying complex line topologies in low-voltage distribution areas according to claim 6, characterized in that, The connection topology between the transmitting node and each upstream receiving node is determined by calculating the comprehensive score of the transmitting node and each upstream receiving node through the following steps: Calculate the current path score based on each current path response coefficient in the current path response coefficient matrix; The driving point impedance of the receiving node is calculated, and the impedance score is calculated based on the difference between each of the perturbation transfer impedances in the perturbation transfer impedance matrix and the driving point impedance of the corresponding receiving node. The driving point impedance is the voltage perturbation signal collected by the identification device at the receiving node divided by the current response signal collected synchronously at the receiving node. The current path score and the impedance score are weighted and summed to obtain the comprehensive score; The higher the overall score, the closer the transmitting node is to the upstream receiving node.

8. A low-voltage distribution area complex line topology identification system that implements the method of any one of claims 1 to 7, characterized in that, include: Multiple identification devices are distributed and deployed in nodes within a low-voltage distribution area. Each identification device includes a characteristic current transmitting circuit module, a characteristic current receiving circuit module, a control processing module, a voltage acquisition module, and a communication module. The characteristic current transmitting circuit module, the characteristic current receiving module, and the voltage acquisition module are respectively connected to the LN loop of the distribution area and are communicatively connected to the control processing module and the communication module, respectively. A cloud platform, wherein the cloud platform includes a task scheduling module, a data transmission module, and a topology identification module, wherein the data transmission module is communicatively connected to the communication module of each of the identification devices, and is also communicatively connected to the task scheduling module and the topology identification module, wherein the task scheduling module sequentially designates one of the identification devices as a transmitting node and the remaining identification devices as receiving nodes, and the data transmission module sends a transmitting command to the identification device designated as the transmitting node; The characteristic current transmitting circuit module of the identification device designated as the transmitting node periodically adds or removes the load to the node, the characteristic current receiving circuit module synchronously collects the characteristic current response signal, and when the characteristic current response signal stabilizes, the communication module notifies the cloud platform. After receiving a notification from the identification device designated as the transmitting node, the cloud platform commands all the identification devices to simultaneously collect the voltage disturbance signal and current response signal at their respective nodes. Using the current response signal at the transmitting node as the characteristic current signal injected into the LN loop, the platform calculates the current path response coefficient and perturbation transfer impedance between the transmitting node and the receiving node, and determines the topological connection relationship between the transmitting node and the receiving node.

9. The low-voltage distribution area complex line topology identification system according to claim 8, characterized in that, The identification device is configured to first acquire the background LN voltage in the uninjected state before injecting the characteristic current into the LN circuit, then inject a probe current with a small amplitude and simultaneously acquire the LN voltage and the actual injected current in the state of injecting the probe current. Based on the voltage disturbance and probe current before and after injecting the probe current, the equivalent impedance presented by the access point to the upstream power supply side is calculated. The equivalent impedance is equal to the ratio of the voltage disturbance to the probe current. The magnitude of the characteristic current injected into the LN circuit is adjusted according to the equivalent impedance.

10. A low-voltage distribution area complex line topology identification device for use in the method of any one of claims 1 to 7, characterized in that, The identification device is suitable for deployment in low-voltage distribution areas and is used to inject characteristic current signals into the LN circuit of the distribution area and / or collect voltage disturbance signals and current response signals in the LN circuit during distribution area line topology identification. The identification device includes: A communication module, wherein the communication module is used to receive transmission commands and reception commands from the cloud platform; A control processing module, wherein the control processing module is communicatively connected to the communication module; A characteristic current transmitting circuit module, wherein the characteristic current transmitting circuit module is connected to the LN circuit of the transformer area, and the characteristic current transmitting circuit module is communicatively connected to the control processing module. The control processing module is configured to control the characteristic current transmitting circuit module to inject a characteristic current into the LN circuit of the transformer area when the communication module receives a transmitting command. A characteristic current receiving circuit module, wherein the characteristic current receiving circuit module is connected to the LN loop of the transformer area and is communicatively connected to the control processing module and the communication module respectively. The control processing module is configured to, when the communication module receives a receiving command, control the characteristic current receiving circuit module to collect the current response signal from the LN loop of the transformer area at the same time as other identification devices deployed in the same transformer area that have also received receiving commands; and A voltage acquisition module is provided, wherein the voltage acquisition module is connected to the LN circuit of the transformer area and is communicatively connected to the control processing module and the communication module respectively. The control processing module is configured to control the voltage acquisition module to acquire voltage disturbance signals from the LN circuit of the transformer area at the same time as other identification devices deployed in the same transformer area that have received the receiving command when the communication module receives the receiving command.

Images