Adaptive fault isolation method and system based on primary and secondary fusion ring network cabinet

Abstract

The application relates to the technical field of power distribution network fault isolation, and particularly discloses a self-adaptive fault isolation method and system based on a primary-secondary fusion ring network cabinet, which comprises a regional coordination terminal and a plurality of intelligent fusion terminals built in the primary-secondary fusion ring network cabinet; the regional coordination terminal is used for acquiring registration parameters of distributed power sources and energy storage devices to construct a dynamic source network load topology graph, performing single-point fault preplay based on the dynamic source network load topology graph, generating an isolation scheme preplan set containing an isolation boundary, and delivering the isolation scheme preplan set to corresponding intelligent fusion terminals. The scheme effectively overcomes the problem of fault feature blurring and fixed value invalidation caused by high-proportion inverter power source access, realizes self-adaptive evolution of the fault isolation strategy with the power grid operation state in a highly dynamic and complex source network load interaction environment, effectively eliminates the communication time delay restriction and the risk of blind override tripping, and guarantees high-reliability and continuous power supply of the non-fault area.

Description

Technical Field

[0001] This invention relates to the field of power distribution network fault isolation technology, and in particular to an adaptive fault isolation method and system based on a primary and secondary integrated ring network cabinet. Background Technology

[0002] With the widespread integration of distributed generation into distribution networks, distribution networks have evolved from single-source, unidirectional power flow networks to complex networks with multiple sources and bidirectional power flow. Existing distribution network fault isolation technologies mainly rely on centralized distribution automation master stations for global information collection and analysis, or use local relay protection devices based on fixed current settings, fixed action delays, and single-directional criteria to achieve fault isolation.

[0003] In real-world application scenarios with high penetration of distributed power sources and frequent changes in network source-grid-load topology, we found that centralized isolation systems are highly dependent on global communication links and have uncontrollable decision-making delays, which cannot meet the requirements for rapid isolation.

[0004] Traditional local protection devices lack global topology awareness. When faced with limited short-circuit current amplitude or drastic power flow reversal caused by inverter power supply, the original fixed settings will fail due to the actual physical environment, which can easily lead to misjudgment of directional elements or large-scale over-level tripping, resulting in an expansion of the power outage range in non-faulty areas. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the purpose of this invention is to propose an adaptive fault isolation method and system based on a primary and secondary integrated ring network cabinet to ensure highly reliable and continuous power supply in fault-free areas.

[0006] To achieve the above objectives, the first aspect of the present invention proposes an adaptive fault isolation system based on a primary and secondary fusion ring network cabinet, including a regional coordination terminal and multiple intelligent fusion terminals built into the primary and secondary fusion ring network cabinet.

[0007] The regional coordination terminal is used to obtain the registration parameters of distributed power sources and energy storage devices to construct a dynamic source-grid-load topology map, and to perform single-point fault simulation based on the dynamic source-grid-load topology map, generate a set of isolation scheme plans including isolation boundaries, and distribute them to the corresponding smart fusion terminal.

[0008] The intelligent fusion terminal is used to generate a dynamic protection domain based on the local power supply adjacency table and the isolation scheme set, and to calculate the basic adaptive delay in real time; when a transient change signal in the distribution network is detected, the fault handling process is initiated, and the directional element is dynamically switched according to the penetration rate of the distributed power supply in the dynamic protection domain to calculate the fault direction and generate a multi-power supply direction code.

[0009] The intelligent fusion terminal is also used to broadcast the multi-power direction encoding to terminals in adjacent communication layers for regional consensus voting. When it is determined that the ring network cabinet is at the boundary of the consensus fault area, a timer bound to the basic adaptive delay is started. During this period, by listening to the tripping action signal of the lower-level terminal that is closer in electrical distance within the fault area, it decides to perform a blocking operation on the ring network cabinet or generate a circuit breaker tripping command, thereby completing the adaptive fault isolation closed loop.

[0010] To achieve the above objectives, a second aspect of the present invention proposes an adaptive fault isolation method based on a primary and secondary integrated ring network cabinet, applicable to a distribution network system including a regional coordination terminal and multiple intelligent integrated terminals built into the primary and secondary integrated ring network cabinet. The method includes:

[0011] The regional coordination terminal obtains the registration parameters of distributed power sources and energy storage devices to construct a dynamic source-grid-load topology map, and performs single-point fault simulation based on the dynamic source-grid-load topology map to generate a set of isolation scheme plans including isolation boundaries and distribute them to the corresponding smart fusion terminal.

[0012] The intelligent fusion terminal generates a dynamic protection domain based on the local power supply adjacency table and the isolation scheme set, and calculates the basic adaptive delay in real time.

[0013] When the intelligent fusion terminal detects a transient change signal in the distribution network, it initiates a fault handling process, dynamically switches directional elements according to the penetration rate of distributed power sources within the dynamic protection domain to calculate the fault direction, and generates a multi-power source direction code.

[0014] The intelligent fusion terminal broadcasts the multi-power direction code to terminals in adjacent communication layers to conduct regional consensus voting. When it is determined that the ring network cabinet is at the boundary of the consensus failure area, a timer bound to the basic adaptive delay is started.

[0015] During the operation of the timer, the intelligent fusion terminal listens to the tripping action signal of the lower-level terminal that is electrically closer in the fault area, and decides to perform a blocking operation on the ring network cabinet or generate a circuit breaker tripping command, thereby completing the adaptive fault isolation closed loop.

[0016] To achieve the above objectives, a third aspect of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory. When the computer program is executed by the processor, it implements the above-described adaptive fault isolation method based on a primary and secondary fusion ring network cabinet.

[0017] This invention deeply integrates topology pre-simulation, dynamic protection domain construction, and multi-terminal collaborative voting mechanisms. In actual distribution network operations, the underlying terminals can calculate and adjust adaptive delays in real time based on the pre-simulation scheme. In the event of a sudden fault, they can dynamically switch to the most suitable fault direction calculation logic based on the actual distributed power source penetration rate to accurately pinpoint the anomaly source. This mechanism enables the underlying devices to autonomously and accurately decide on physical tripping or blocking by initiating consensus voting with adjacent nodes and verifying the lower-level action status using delay-based interlocking control logic, even when operating conditions largely free from dependence on the master station.

[0018] This solution effectively overcomes the problems of ambiguous fault characteristics and setpoint failure caused by high proportion of inverter power supply access. In a highly dynamic and complex source-grid-load interaction environment, it realizes the adaptive evolution of fault isolation strategy with the grid operation status, effectively eliminates communication delay constraints and the risk of blind over-tripping, and ensures high reliability and continuous power supply in fault-free areas. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the implementation of the adaptive fault isolation system based on a primary and secondary fusion ring network cabinet provided by the present invention.

[0020] Figure 2 This is the basic adaptive delay three-dimensional response surface diagram of the adaptive fault isolation system based on primary and secondary fusion ring network cabinet provided by the present invention;

[0021] Figure 3 This is a comparison diagram of the multi-modal signal processing waveforms of transient energy direction elements in the adaptive fault isolation system based on primary and secondary fusion ring network cabinets provided by this invention.

[0022] Figure 4 This invention provides a frequency domain thermal bitmap of the background harmonic energy distribution of the inverter in an adaptive fault isolation system based on a primary and secondary fusion ring network cabinet.

[0023] Figure 5 This is a scatter plot of the phase angle variation trajectory and fluctuation variance of passive and active impedances in the adaptive fault isolation system based on primary and secondary fusion ring network cabinet provided by the present invention.

[0024] Figure 6 This is a transient waveform diagram of current decay and voltage recovery within the local physical verification observation window of the adaptive fault isolation system based on primary and secondary fusion ring network cabinet provided by the present invention.

[0025] Figure 7 This is the evolution diagram of the regional consensus voting multi-power direction coding state matrix in the adaptive fault isolation system based on primary and secondary fusion ring network cabinets provided by the present invention;

[0026] Figure 8 This is a flowchart illustrating the adaptive fault isolation method based on primary and secondary fusion ring network cabinets provided by the present invention.

[0027] Figure 9 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0029] The adaptive fault isolation system, method, and electronic equipment based on a primary and secondary fusion ring network cabinet according to embodiments of the present invention are described below with reference to the accompanying drawings.

[0030] Example 1:

[0031] like Figure 1 As shown, this embodiment provides an adaptive fault isolation system based on a primary and secondary integrated ring network cabinet. The physical architecture of the distribution network system involved in this embodiment consists of main grid substation outgoing lines, multiple feeders, multiple physical nodes, and loads and power supplies connected to each node. In this system, underlying hardware devices including regional coordination terminals and multiple intelligent integrated terminals built into the primary and secondary integrated ring network cabinets are widely deployed.

[0032] Specifically, the aforementioned integrated primary and secondary ring main unit refers to power equipment that deeply integrates primary high-voltage switchgear (such as vacuum circuit breakers and load switches) with secondary measurement and control protection equipment during the manufacturing stage. Internally, it uses electronic voltage transformers and electronic current transformers to replace traditional electromagnetic transformers. The primary and secondary equipment are directly electrically connected via plug-in sensors, eliminating parasitic capacitance and electromagnetic interference caused by traditional hard-wired cables. The underlying communication and sampling hardware architecture of the intelligent integrated terminal includes a built-in high-precision synchronous sampling module supporting a precise time synchronization protocol, and a built-in dual-redundant fiber optic bus communication interface.

[0033] For example, the hardware architecture of this high-precision synchronous sampling module is built on a collaborative structure of a field-programmable gate array (FPGA) and a digital signal processor (DSP), supporting the precision time synchronization protocol in the IEEE standard. This protocol enables hardware-level timestamp alignment among various intelligent converged terminals widely distributed across the distribution network, controlling the global node sampling synchronization error to within microseconds. This microsecond-level synchronization mechanism is fundamental for extracting transient high-frequency features and harmonic impedance features, ensuring the data alignment accuracy of transient energy and harmonic impedance feature extraction and preventing divergence in the direction discrimination formula due to phase shifts caused by multi-point sampling.

[0034] Meanwhile, the built-in dual-redundant fiber optic bus communication interface is equipped with a priority scheduling algorithm, which classifies and parses data frames at the underlying media access control layer. This algorithm sets the transmission priority of regional consensus voting data packets and refusal-to-operate overstepping instruction data packets to be higher than that of regular remote monitoring data streams, ensuring that neighborhood interaction information is delivered within the preset communication delay threshold and guaranteeing the timeliness of distributed collaborative logic.

[0035] Based on this hardware architecture, the system in this embodiment executes the following steps of a fault adaptive isolation method based on time and logical sequence:

[0036] Step 1: System initialization and dynamic source-load topology modeling.

[0037] Specifically, the regional coordination terminal is used to obtain registration parameters of distributed power sources and energy storage devices to construct a dynamic source-grid-load topology. When the distribution network is put into operation or a new node is added, the underlying controllers of various types of distributed power sources (such as photovoltaic inverters and wind turbines) and energy storage devices report registration parameters to the regional coordination terminal within their respective jurisdictions through standard communication protocols. The registration parameters include, but are not limited to, the rated active power, rated reactive power, short-circuit current supply capacity coefficient, control topology type, and geospatial coordinate mapping identifier of the devices. Based on the received registration parameters, the central processing unit of the regional coordination terminal uses graph theory algorithms to generate a dynamic source-grid-load topology with nodes and edges as the core data structure.

[0038] Based on the dynamic source-grid-load topology, the regional coordination terminal performs single-point fault pre-simulation, generates a set of isolation scheme contingency plans including isolation boundaries, and distributes them to the corresponding intelligent converged terminals. The triggering mechanism for the regional coordination terminal to perform single-point fault pre-simulation includes: performing rolling pre-simulation under steady-state conditions according to a preset time period (e.g., every fifteen minutes); or triggering full-scenario single-point fault pre-simulation when the distributed power output change rate in the dynamic source-grid-load topology exceeds a first preset threshold, the load change rate exceeds a second preset threshold, or the switching state of any node changes.

[0039] For example, when a large distributed photovoltaic power station in a certain area experiences a drop in active power due to a sudden change in sunlight, and the rate of change in distributed power output calculated from the drop rate and its magnitude exceeds the first preset threshold defined as the extreme value of steady-state fluctuation, the regional coordination terminal determines that the current power flow distribution and short-circuit current distribution characteristics have undergone substantial shifts. It then uses a pre-set parallel power flow calculation core to initiate hypothetical fault calculations traversing all nodes of the distribution network. Through this full-scenario single-point fault simulation, the fault evolution path for each hypothetical fault node is calculated. The isolation scheme set explicitly includes the target set of tripped switches, the optimal islanding scheme, and source-grid-load coordinated control parameters for each single-point fault scenario. This set is compiled into a structured data table, distributed via fiber optic network, and resides in the local high-speed static random access memory of each intelligent converged terminal.

[0040] Step 2: Dynamic protection domain generation and basic adaptive delay calculation.

[0041] Specifically, the intelligent fusion terminal generates a dynamic protection domain based on the local power supply adjacency table and the isolation scheme set, and calculates the basic adaptive delay in real time. By parsing the dynamic source-network-load topology, the intelligent fusion terminal identifies the upstream and downstream power supply nodes with the closest electrical distance to its current node, forming a local power supply adjacency table. Combined with the isolation scheme set residing in its local memory, the intelligent fusion terminal logically defines the power distribution line segment it is responsible for monitoring and protecting, i.e., the dynamic protection domain.

[0042] It is also important to note that the equivalent moment of inertia and disturbance rejection capability within this dynamic protection domain change in real time with fluctuations in the output of the distributed power source. Therefore, the intelligent fusion terminal calculates the basic adaptive delay in real time according to a specific mathematical relationship. Time-related parameters are defined so that the value of the basic adaptive delay is obtained by multiplying a preset reference time constant by a time adjustment coefficient.

[0043] The calculation logic is set as follows:

[0044] ;

[0045] ;

[0046] ;

[0047] Among them, variables This represents the penetration rate of distributed power sources within a protected area, defined as the total installed capacity of distributed power sources within that protected area. With total load capacity variable The ratio; variable Indicates time adjustment factor; variable This represents the minimum time adjustment coefficient lower limit preset by the system (e.g., a value of 0.1), used to prevent logic overflow caused by calculating negative delays under extremely high penetration conditions; Variable This represents the penetration rate correction factor, a constant determined by offline simulation, used to characterize the weight of the power source type on the system stability margin; variables Indicates the total number of power supply nodes contained within the dynamic protection domain; variable Indicates the basic adaptive delay; variable This represents the preset reference time constant, which indicates the reference level coordination delay in the case of traditional distribution networks without distributed generation access.

[0048] Based on the logic constructed by the above three formulas, the numerator of the time adjustment coefficient is 1 minus the product of the penetration rate correction coefficient and the distributed power source penetration rate within the protection domain, and the denominator of the time adjustment coefficient is the total number of power source nodes contained in the dynamic protection domain. The physical meaning of this logic in actual distribution network operations is that when the distributed power source penetration rate within the protection domain increases, the risk of distributed power source disconnection caused by voltage drops after a system fault increases non-linearly. Therefore, it is necessary to dynamically compress the differential delay to accelerate isolation and prevent the fault range from expanding. Simultaneously, the larger the total number of power source nodes, the higher the complexity of multi-source coordinated scheduling, requiring a shorter single-node decision time to meet global convergence constraints. When the intelligent fusion terminal identifies the current dynamic protection domain as an end-island protection domain (i.e., an independent microgrid area that no longer has power interaction with the upper-level main grid), it forcibly resets the basic adaptive delay to zero, achieving instantaneous fault isolation within this area without delay.

[0049] like Figure 2 This figure visually demonstrates the nonlinear adjustment mechanism of key operating parameters within the dynamic protection domain of the distribution network on the fault isolation decision time. In the three-dimensional coordinate system of this figure, the horizontal axis represents the distributed generation penetration rate, the vertical axis represents the total number of power nodes (in units), and the vertical axis represents the basic adaptive delay (in milliseconds).

[0050] The overall spatial distribution of the curved surfaces and the gradual change in color temperature clearly reflect the evolution of the delay strategy as the system operates.

[0051] When the penetration rate of distributed power sources is at a low level close to zero and the total number of power nodes is only one, the surface is in the corresponding highest red area, and the basic adaptive delay reaches the preset benchmark value of 20 milliseconds, which means that the traditional distribution network has the most generous differential coordination time at this time.

[0052] As the penetration rate of distributed power sources on the horizontal axis gradually increases to 1, the surface shows a clear non-linear downward curve trend, indicating that the high proportion of inverter power supply access increases the risk of large-scale grid disconnection caused by voltage drop after system failure. The control system actively compresses the action delay.

[0053] Similarly, when the total number of power nodes on the vertical axis increases to 10, the surface exhibits a smooth decaying waveform in the other direction, indicating that the increased complexity of multi-source collaborative scheduling prompts the system to allocate shorter single-node decision times. The surface color transitions from a warm-toned red high-latency region to a cool-toned blue low-latency region, reflecting the increased urgency of the system response.

[0054] Especially in extreme operating conditions with high penetration and multiple concurrent nodes, i.e., the gently sloping bottom surface in the dark blue area of ​​the figure, the curved surface stops descending and maintains a horizontal extension. The delay value is forcibly clamped to the minimum safe lower limit of two milliseconds. This morphological feature confirms the effectiveness of the lower limit dead zone protection in the delay calculation logic from the data. It ensures that in the complex source-grid-load interaction environment, the delay parameter calculated by the underlying intelligent terminal device is always higher than the limit time threshold of the physical actuator, thus taking into account both the need for rapid local isolation of faults and the logical reliability of distribution network protection actions.

[0055] Step 3: Multimodal fault feature extraction and adaptive switching of directional elements.

[0056] Specifically, when the intelligent fusion terminal detects a transient change signal in the distribution network, it initiates a fault handling process, dynamically switching directional elements based on the penetration rate of distributed power sources within the dynamic protection domain to calculate the fault direction. The transient change signal in the distribution network is a trigger signal where the effective derivative of the three-phase current or the effective derivative of the phase voltage, continuously calculated by the intelligent fusion terminal through a high-frequency sampling module, exceeds the steady-state noise range. After initiating the fault handling process, to address the technical challenge of traditional overcurrent direction criteria failing due to the connection of high-proportion power electronic converters (i.e., inverter-type distributed power sources), the system executes multi-mode adaptive switching logic.

[0057] Optionally, the intelligent fusion terminal dynamically switches directional elements to calculate the fault direction based on the penetration rate of distributed power sources within the dynamic protection domain, including the following three parallel action branches:

[0058] First branch: When there is no inverter-type distributed power source or the penetration rate of inverter-type distributed power sources in the dynamic protection domain is lower than the preset first penetration rate threshold, the short-circuit current characteristics of the distribution network are mainly provided by synchronous generators or the main system grid, exhibiting obvious power frequency characteristics. At this time, the intelligent fusion terminal activates the power frequency negative sequence and zero sequence directional elements, and uses the full-wave Fourier algorithm to extract the phase difference of the power frequency fault component to determine the fault direction.

[0059] The second branch: When the penetration rate of the inverter-type distributed power source is greater than or equal to the first penetration rate threshold and the fault current is higher than the preset first current multiple threshold, the low voltage ride-through and current limiting control strategy inside the inverter will intervene several milliseconds after the fault occurs, clamping the output current within a safe limit, causing the power frequency phasor to lose its directional orientation. At this time, the intelligent fusion terminal activates the transient energy direction element to extract the transient energy flow direction within the initial time window of the fault to determine the fault direction.

[0060] Specifically, the transient energy calculation logic is defined as follows under this operating condition:

[0061] ;

[0062] Among them, variables Represents the extracted transient energy integral value; variable Indicates the start time of detecting transient change signals in the distribution network; variable This indicates the duration of the initial fault time window, which is typically set before the inverter control loop response time; variable Indicates the variable during integration time. Transient voltage instantaneous feature extracted at each time step; variables Indicates the variable during integration time. The transient current instantaneous characteristic quantity extracted at each moment. If the calculated transient energy integral value is positive, the fault point is determined to be located on the positive reference direction side; otherwise, it is located on the negative direction side.

[0063] The third branch: When the penetration rate of the inverter-type distributed power source is greater than or equal to the first penetration rate threshold and the fault current is lower than the first current multiple threshold, this operating condition typically corresponds to a high-resistance grounding fault. At this time, the fault current is extremely weak, and both transient energy and power frequency characteristics are submerged in background noise. The intelligent fusion terminal activates the harmonic impedance direction element, injecting a high-frequency detection signal into the system and measuring the harmonic impedance change characteristics to determine the fault direction. This process utilizes a specific high-frequency modulation module in the primary and secondary fusion hardware to couple a voltage pulse of a specific frequency to the primary bus, and calculates the polarity of the physical impedance by analyzing the high-frequency current phasor of the response.

[0064] Based on the above calculation results, the intelligent fusion terminal generates a multi-power direction code. For example, the multi-power direction code generated by the intelligent fusion terminal is a fixed-bit binary feature sequence, including multiple power direction feature bits and a fault type identifier bit. In the register structure of the actual digital signal processor, each power direction feature bit strictly corresponds to a power node in the dynamic source-load topology. When the calculated fault point is located between the corresponding ring main unit and the corresponding power node, the power direction feature bit is assigned a first logic state (e.g., logic high level "1"); when the fault point is located on the side of the ring main unit away from the corresponding power node, it is assigned a second logic state (e.g., logic low level "0"). The fault type identifier bit occupies an independent feature bit and is used to distinguish between phase-to-phase short-circuit faults and single-phase ground faults, so as to facilitate the subsequent activation of isolation logic for different phases.

[0065] like Figure 3 This figure visually demonstrates the dynamic signal processing of a smart fusion terminal for fault direction determination under conditions of high penetration of inverter-type distributed power sources and limited fault short-circuit current. The horizontal axis represents time in milliseconds, and the entire observation window covers an evolution period from 0 to 10 milliseconds. The left vertical axis represents transient voltage and current amplitudes in per-unit values, and the right vertical axis represents the transient energy integral in microjoules.

[0066] In the graphical representation, the solid blue line represents the extracted transient voltage waveform, and the dashed red line represents the extracted transient current waveform. After the power distribution network transient change occurs at 2 milliseconds, the peak value of the transient current waveform is limited to around 1.5 per unit due to the intervention of the inverter current limiting control strategy. It also exhibits a rapidly decaying oscillating pattern along with the transient voltage waveform. This reflects the physical fact that the traditional power frequency overcurrent criterion loses its directional orientation at this stage.

[0067] To address this issue, the system activates the transient energy direction element, multiplies the acquired voltage and current transient characteristics, and accumulates them over time, forming the transient energy integral curve represented by the bold green solid line in the figure. Within the initial 5-millisecond time window after the fault occurs, i.e., from the 2nd to the 7th millisecond, this curve exhibits a continuously rising positive step shape.

[0068] This positive accumulation of energy flow provides an independent verification basis for the system, enabling the intelligent fusion terminal to determine that the fault point is located on the reference positive direction side based on the calculated positive transient energy integral value, thereby ensuring the reliability of multi-power direction code generation under complex operating conditions where the inverter output current is limited.

[0069] Step 4: Collaborative confirmation of fault boundaries based on regional consensus voting.

[0070] Specifically, the intelligent fusion terminal broadcasts the multi-power source direction code to terminals in adjacent communication layers for regional consensus voting. In complex multi-power source networks, measurements from a single node may be inaccurate due to transient saturation of the transformer or high-frequency interference. The system employs a distributed consensus mechanism based on point-to-point communication to improve fault tolerance.

[0071] Optionally, the rule for the intelligent fusion terminal to conduct regional consensus voting is as follows: Data packets carrying the multi-power source direction encoding and fault initiation flags are encapsulated into Ethernet messages oriented towards general-purpose substation events and sent to terminals at adjacent communication layers. If the number of adjacent terminals participating in receiving the data packets reaches the minimum voting threshold (this threshold is a lower limit set to prevent single-point decision-making risks caused by communication islands), consensus ratio calculation begins.

[0072] The consensus ratio calculation logic is defined as follows:

[0073] ;

[0074] Among them, variables This represents the calculated actual value of the consensus ratio; variables. This indicates the number of terminals that participated in the voting and whose multi-power-direction codes point to the same faulty segment; variable This indicates the total number of votes received and validly encoded by the terminal. If the calculated consensus ratio exceeds a preset consensus threshold, this segment is locked as a consensus failure area.

[0075] If the consensus threshold cannot be reached at the current communication level due to severe external electromagnetic interference, the voting scope will be expanded to outer physical nodes step by step through the layer-by-layer routing and forwarding function of the message, according to the dynamic source-load topology diagram. New measurement samples will be added to the outer nodes to participate in the formula calculation until a consensus failure area is formed, or the system will switch to a degradation protection mode after exhausting all reachable nodes.

[0076] Step 5: Adaptive interlocking and trip isolation execution.

[0077] Specifically, when the system determines that its ring network cabinet is at the boundary of the consensus fault zone, the intelligent fusion terminal starts a timer bound to the basic adaptive delay. At this point, the system enters the distributed fault tolerance judgment phase.

[0078] For example, the control logic for the intelligent fusion terminal to decide whether to perform a blocking operation on its affiliated ring main unit or generate a circuit breaker trip command is as follows: After starting the timer, the intelligent fusion terminal located at the boundary of the consensus fault area physically keeps the circuit breaker in the closed state, while continuously scanning the receive buffer of the dual-redundant fiber optic bus communication interface. If, before the timer expires, a successful trip feedback signal is received from a lower-level terminal that is electrically closer within the fault area, this means that the physical switch closer to the fault point has already cut off the short-circuit current, and this node does not need to take action. At this time, the intelligent fusion terminal triggers the interrupt service subroutine of the central processing unit, terminates the timer, and physically blocks the tripping circuit of the circuit breaker of its affiliated ring main unit, thus avoiding non-selective cascading tripping.

[0079] Conversely, if the timer expires without receiving the successful trip feedback signal, it is determined that the lower-level node has failed to effectively clear the fault (possibly due to power failure of the lower-level communication equipment or mechanical jamming). At this critical moment, the intelligent fusion terminal immediately generates the circuit breaker trip command, driving the thyristor of the closed operation circuit on the drive output board to trip the circuit breaker of the corresponding ring network cabinet, completing the backup isolation of the fault. In addition, to prevent a large amount of current from flowing from the distributed power source inside the island to the fault point due to the disconnection of the main grid at the moment of tripping, the intelligent fusion terminal issues an active current limiting command to the distributed power source in the non-faulty area within the synchronous microsecond period of generating the circuit breaker trip command. After receiving the command, the underlying controller of the inverter-type distributed power source instantaneously changes the duty cycle of the pulse width modulation waveform to limit its output current within a preset current limiting multiple threshold, thereby protecting the physical safety of the power electronic devices.

[0080] Step Six: Seamless island recovery through multi-level fail-to-operate backup logic and source-network-load collaboration.

[0081] It is also important to note that outdoor primary switchgear in power distribution networks operates in complex environments for extended periods, and its mechanical operating mechanisms are subject to a certain probability of failure. To address this, the intelligent fusion terminal incorporates multi-power source coordinated multi-level backup protection logic: it synchronously extracts the circuit breaker auxiliary contact change status, the continuous status of the fault current waveform, and the arc extinguishing signal within the cabinet as multiple feature criteria. After generating a circuit breaker trip command, if the auxiliary contact level does not reverse, the high-frequency sampling module continuously calculates a large current flow, and the photoelectric sensor does not capture the arc extinguishing light signal from the vacuum interrupter, then the abnormal operation status of the circuit breaker in the corresponding ring main unit is detected and determined in real time.

[0082] When a circuit breaker in a ring main unit fails to trip, the intelligent fusion terminal broadcasts a fault-level over-level instruction to all directly adjacent power supply terminals. This mechanism breaks the linear structure of traditional distribution networks that only request backup tripping from a single upstream substation. Upon receiving the over-level instruction, adjacent terminals forcibly reduce their own basic adaptive delay according to a preset ratio (e.g., reducing the value calculated in step two to a preset fractional level) to accelerate the execution of over-level backup isolation within a very short time window, preventing heat accumulation from faulty equipment from causing fires or busbar burnout.

[0083] Finally, after completing adaptive fault isolation, the system triggers a seamless islanding operation mode for source-grid-load coordination. Because the isolation action disconnects the faulty section, some healthy lines may lose their electrical connection to the main grid. At this time, the intelligent converged terminal in the non-faulty area automatically invokes the optimal islanding scheme from the set of isolation schemes described in step one, disconnecting the physical connection switch with the main grid to form a clear microgrid physical boundary.

[0084] Within this boundary, the intelligent fusion terminal issues a wake-up command via local communication to activate the voltage and frequency control mode of the energy storage device. The energy storage system provides a stable reference phase angle and frequency to establish the reference voltage and frequency for the islanded microgrid. Subsequently, based on the preset safe load priority matrix, and provided that the system frequency and voltage steady-state convergence is detected, the load switches of the relevant nodes are closed sequentially to restore power supply to the distributed power source and load nodes at all levels. During islanded independent operation, the intelligent fusion terminal continuously collects synchronous voltage data from the main grid. When it detects that the main grid voltage has recovered and meets the synchronous grid connection conditions (i.e., frequency difference, voltage difference, and phase difference are all within the minimum tolerance range), it automatically executes the synchronous grid connection operation to close the tie switch and restore global grid-connected power supply.

[0085] The system disclosed in this embodiment combines the physical conditions of high randomness, bidirectional power flow, and fault characteristic distortion presented by distributed power access in actual operation. It constructs a complete technical chain within the underlying intelligent device, from topology dynamic identification to feature multimodal extraction, and then to communication area consensus and delay adaptive blocking.

[0086] Compared to existing centralized power distribution automation systems that heavily rely on master station computation and long-distance communication links, leading to slow isolation, this solution's pre-simulation mechanism and graph-based power adjacency list technology shift the computational burden to edge devices, enabling rapid local decision-making. Furthermore, unlike existing technologies where traditional protection relays, based on fixed action settings and single power frequency phasors, are prone to malfunction under inverter current-limited conditions, this solution utilizes three algorithms—dynamic scheduling of transient energy based on permeability and current multiple, power frequency phasors, and high-frequency harmonic impedance—along with hardware-level precise time synchronization, establishing a directional discrimination benchmark adaptable to highly nonlinear environments.

[0087] This embodiment, based on a neighborhood collaborative anti-level blocking mechanism with dynamic base delay, embeds information flow verification before the energy flow cutoff sequence, effectively preventing the risk of blind tripping caused by dynamic topology reconfiguration. Ultimately, this solution enables distribution networks with a high proportion of inverter power supplies to possess intelligent self-healing and smooth, seamless islanding switching capabilities without master station intervention, greatly improving power supply continuity and grid operational resilience.

[0088] Example 2:

[0089] In the actual operation of modern power distribution networks, when a high-resistance ground fault occurs, such as a tree branch touching a wire or severe flashover on the insulator surface, the amplitude of the fault short-circuit current is extremely weak due to the large transition resistance at the fault point, often lower than the starting setting value of conventional overcurrent protection. In such high-resistance fault scenarios, especially in distribution network areas with high penetration rates of inverter-type distributed power sources, the internal control strategies of grid-connected inverters (such as phase-locked loop control and inner current loop regulation) exhibit highly dynamic nonlinear regulation characteristics.

[0090] This nonlinear regulation not only continuously injects a large amount of broadband background harmonics into the distribution network, but also causes the inverter to exhibit drastically fluctuating "active impedance" characteristics at the port. Most existing fault direction detection technologies employ a high-frequency signal injection method with a single fixed frequency (usually an integer multiple of the power frequency harmonic). These traditional methods face two major physical dilemmas in practical operation:

[0091] First, the fixed-frequency injection signal is very likely to overlap with the dynamic background harmonic frequency generated by the inverter, causing the effective signal to be submerged by environmental noise and the signal-to-noise ratio to deteriorate sharply.

[0092] Secondly, traditional methods only measure the static absolute value of impedance at a single moment, and cannot distinguish from the physical nature of whether the impedance measurement result comes from a real physical fault branch (i.e., a passive impedance with an objectively stable phase angle) or from an equivalent false impedance (i.e., an active impedance) generated by severe disturbances in the inverter control loop. This can easily lead to misjudgment or failure of the directional element.

[0093] To address the challenge of accurately isolating high-resistance faults in distribution networks, this embodiment discloses a technical logic for determining the fault direction by injecting high-frequency detection signals into the system and measuring the characteristics of harmonic impedance changes. Specifically, it includes the following dynamic anti-interference identification steps.

[0094] Optionally, under normal operating conditions, the intelligent fusion terminal collects and records the broadband background harmonic distribution characteristics within the dynamic protection domain in real time, constructing a dynamic impedance baseline model to characterize the background interference of inverter-type distributed power sources. During steady-state operation of the distribution network without faults, the high-precision synchronous sampling module inside the primary and secondary fusion ring network cabinet is continuously operational, extracting discrete waveform data of voltage and current in real time at a preset high sampling rate, such as more than 250 sampling points per second. The digital signal processing core built into the intelligent fusion terminal uses a sliding window fast Fourier transform algorithm to continuously convert the time-domain waveform into a frequency-domain spectrum, thereby extracting and recording the unique broadband background harmonic distribution characteristics within this specific dynamic protection domain.

[0095] This distribution characteristic is not static but is updated in real time based on the output levels of inverter-type distributed power sources such as photovoltaics and energy storage during different periods of sunlight or load. Based on the accumulation of long-term frequency domain data, the intelligent fusion terminal constructs a dynamic impedance baseline model in its local memory. This model is essentially a multi-dimensional frequency domain energy matrix that maps in detail the probability distribution density of background interference energy in different frequency bands within the current protection domain, thus providing accurate environmental data support for the adaptive selection of subsequent detection signals.

[0096] like Figure 4 This figure visually presents the distribution characteristics of background interference energy generated by inverter-type distributed power sources under high penetration conditions during steady-state operation. The horizontal axis of the figure represents frequency in Hertz, with data ranging from 0 to 5000 Hertz; the vertical axis represents time in seconds, recording a continuous observation process from 0 to 10 seconds; the color gradient in the figure reflects harmonic energy density in decibels.

[0097] In the color distribution shown in the graph, the warm red and orange areas represent frequency bands with highly concentrated energy. It can be clearly observed from the graph that there are significant energy spikes at the 50 Hz base frequency and around 250 Hz and 3000 Hz. This reflects the active interference in the fixed frequency band caused by the switching operation of nonlinear electronic devices and the regulation of the control loop inside the inverter.

[0098] Conversely, the cool-toned dark blue regions constitute frequency troughs with extremely weak energy distribution; for example, in the frequency range of 1500 Hz to 2500 Hz, the harmonic energy density is significantly low. This frequency domain spectrum, exhibiting alternating high-energy and low-energy regions, constitutes the dynamic impedance baseline model established within the system.

[0099] Based on the logic above, the intelligent fusion terminal adaptively selects appropriate non-integer harmonic frequencies to synthesize dual-frequency orthogonal characteristic detection signals, according to the frequency range of the cool-toned valley regions in the diagram. Through this frequency-domain energy density-based filtering mechanism, the system can actively avoid the high-energy-density red interference bands in the diagram, ensuring that the injected high-frequency detection signal achieves a sufficient signal-to-noise ratio in complex electromagnetic environments, thus providing reliable environmental data support for the accurate identification of high-resistance grounding fault directions.

[0100] For example, when the harmonic impedance direction element is activated, the intelligent fusion terminal queries the dynamic impedance baseline model, adaptively synthesizes, and injects a dual-frequency orthogonal characteristic detection signal containing at least two non-integer harmonic frequencies into the system. When the intelligent fusion terminal detects a transient electrical quantity that meets the characteristics of a high-impedance fault, and triggers the execution of the third branch strategy based on the penetration rate condition of the inverter-type distributed power supply in the current protection domain, the system does not blindly send detection signals.

[0101] At this point, the central control unit of the intelligent fusion terminal actively queries and reads the dynamic impedance baseline model established in the previous steps. Based on the frequency domain interference distribution map provided by this baseline model, the signal synthesis algorithm module inside the intelligent fusion terminal automatically finds the two frequency band troughs with the weakest energy distribution and dynamically calculates and selects two non-integer harmonic frequencies accordingly. The fundamental purpose of selecting non-integer harmonic frequencies is to completely avoid the basic characteristic harmonics in the distribution network that exist in the form of integer multiples of the power frequency from a mathematical perspective. At the same time, the algorithm sets strict avoidance conditions, that is, the selected frequencies must avoid the frequency bands in the broadband background harmonic distribution characteristics where the energy amplitude exceeds a preset peak threshold, thereby ensuring that the detection signal can obtain the maximum anti-interference signal-to-noise ratio after being injected into the distribution network.

[0102] Specifically, the time-domain mathematical expression of the dual-frequency orthogonal feature detection signal adaptively synthesized by the intelligent fusion terminal is generated according to the following algorithm logic:

[0103] ;

[0104] In the formula for this dual-frequency orthogonal signal synthesis algorithm, the variables are... Indicates the variable during integration time. The intelligent fusion terminal injects synthetic dual-frequency orthogonal features into the system to detect instantaneous voltage values; variables This represents the pre-set amplitude parameter of the injected voltage characteristic component. This parameter is set to ensure sufficient signal penetration without interfering with the normal power frequency voltage quality of the distribution network; [Variable] This indicates the first non-integer harmonic frequency selected by the intelligent fusion terminal based on the dynamic impedance baseline model; variable This indicates the second non-integer harmonic frequency selected by the intelligent fusion terminal through dynamic calculation.

[0105] The combination of sine and cosine functions endows the two different frequency detection signals with approximately orthogonal characteristics in the signal space within a specific observation time window. The core function of this injection strategy based on a dual-frequency orthogonal architecture in practical applications is that even if a sudden, strong electromagnetic interference of a specific frequency in the power grid happens to overwhelm the first non-integer harmonic frequency, the system can still rely on the independent channel information carried by the second non-integer harmonic frequency to complete impedance feature extraction, greatly improving the physical robustness of the detection method in harsh electromagnetic environments.

[0106] It is also important to note that the intelligent fusion terminal synchronously extracts the differential impedance response characteristics generated at the injection point by the dual-frequency orthogonal characteristic detection signal, and calculates the impedance phase angle change trajectory of this differential impedance response characteristic within a preset observation time window. After the external injection of the detection signal is completed, the high-frequency sampling module of the intelligent fusion terminal synchronously records the electrical response of the local port at high frequency. Through digital bandpass filter banks or generalized second-order generalized integrator phase-locked loop technology, the intelligent fusion terminal accurately extracts the response current characteristic component that strictly corresponds to the first and second non-integer harmonic frequencies from the total current sequence mixed with power frequency fault current and inverter background noise. Combined with the synchronously recorded injected voltage component, the system continuously calculates the complex impedance value at each discrete sampling step, and then solves for the impedance phase angle time sequence over time, which is defined as the differential impedance response characteristic. In order to quantitatively analyze the physical stability of this differential impedance response characteristic on the time axis, the intelligent fusion terminal compiles it into an impedance phase angle change trajectory and applies discrete statistical algorithms to evaluate its fluctuation degree.

[0107] Specifically, the calculation logic for the fluctuation variance of the impedance phase angle change trajectory follows the following discrete sequence statistical algorithm:

[0108] ;

[0109] In the formula, variables This represents the actual measured value of the fluctuation variance of the impedance phase angle change trajectory obtained from the final calculation. This parameter is the core criterion for characterizing whether the impedance measured by the system is active or passive; variable This represents the total number of valid discrete sampling calculation points contained within the preset observation time window; variable This indicates that within the preset observation time window, the first... The instantaneous value of the impedance phase angle extracted from each sampling calculation point; variables This represents the arithmetic mean of the impedance phase angle values ​​extracted from all valid sampling calculation points within the preset observation time window. This calculation logic is executed at high speed within the processor in the form of a scrolling window, outputting variance index data in real time that reflects the dynamic dispersion of the impedance phase angle. In practical engineering physics, this fluctuation variance reflects the degree of divergence of the extracted impedance characteristics over time.

[0110] like Figure 5 This visually demonstrates the impedance dynamic characteristics extracted by the intelligent fusion terminal within a preset observation time window and its classification and identification mechanism. The horizontal axis of the figure represents the sampling time in milliseconds, and the vertical axis represents the impedance phase angle in degrees.

[0111] The trajectory formed by the blue scattered points in the figure represents the phase angle change of the passive physical impedance. It can be seen that these scattered points are closely clustered around 45 degrees with minimal fluctuation. The actual measured value of the fluctuation variance is significantly lower than the preset passive physical branch identification threshold. In actual engineering, this indicates that the impedance phase angle of the loop in a real high-resistance grounding fault caused by purely physical media such as tree branch splicing or line breakage touching the ground is objective and constant.

[0112] In contrast, the trajectory formed by red scatter points in the figure represents the change in the equivalent impedance phase angle when disturbed by the active control strategy of the inverter. These scatter points show a violent discrete oscillation distribution as the sampling time progresses, spanning a wide range of 20 degrees to 70 degrees. The actual measured value of the calculated fluctuation variance increases sharply and exceeds the identification threshold. This accurately reflects the dynamic nonlinear adjustment characteristics of the phase-locked loop controller and the inner current loop controller inside the inverter during the fault transient process in order to track the grid frequency phase and suppress overcurrent.

[0113] By distinguishing the colors and comparing the degree of dispersion of these two trajectories, it was confirmed that the system can effectively identify the passive real impedance generated by the physical medium and the active interference impedance generated by the power electronic equipment by calculating the fluctuation variance index in real time. This avoids misjudgment of directional components under harsh operating conditions with high inverter penetration and provides objective data support for the subsequent decisive abandonment of contaminated measurement results and triggering of a global degradation protection strategy.

[0114] For example, based on the above calculation results, the system performs a strict physical attribute identification branch:

[0115] The first identification scenario: If the fluctuation variance of the impedance phase angle change trajectory is lower than the preset passive physical branch identification threshold, then the true stable impedance of the fault point is confirmed to have been extracted, and the final fault direction is determined based on the polarity of the true stable impedance of the fault point. From the physical essence of distribution network operation, if a high-resistance fault is caused by physical media such as tree branches splicing wires or a broken line touching the actual ground, the fault point and the loop it forms exhibit conductivity, permittivity, and permeability characteristics composed of a fixed medium. The phase angle parameters of these passive impedances, composed of purely physical properties, are objectively constant and highly stable within an observation time window of tens of milliseconds, without drastic phase angle deflection or jumps. Therefore, in such real physical fault scenarios, the actual measured value of the fluctuation variance calculated by the system using the aforementioned algorithm will be extremely small, inevitably lower than the set passive physical branch identification threshold.

[0116] At this point, the intelligent fusion terminal is logically confident that the currently acquired high-frequency harmonic impedance phase angle is not affected by external active equipment, and its measurement results directly reflect the constitutive characteristics of the actual fault circuit. Furthermore, the intelligent fusion terminal utilizes the quadrant position and polarity characteristics of the stable impedance at the fault point within the complex plane to accurately determine the actual direction of the fault current, outputting a high-confidence positive or negative direction determination result.

[0117] Optionally, the second identification scenario constitutes the core safety redundancy defense line for dealing with extreme and harsh operating conditions in this embodiment: if the fluctuation variance is greater than or equal to the passive physical branch identification threshold, it is determined that the current harmonic impedance measurement is interfered with by the inverter's active control strategy, the intelligent fusion terminal abandons the output direction determination result, and triggers a degradation protection strategy to request global fault location from the regional coordination terminal.

[0118] During the transient process following a fault, a local voltage drop in the distribution network can cause inverters with high penetration within the protection zone to rapidly initiate low-voltage ride-through control procedures. The phase-locked loop controller inside the inverter generates dynamic oscillations to track the rapidly changing grid frequency phase, while its inner current loop controller performs nonlinear limiting intervention to suppress overcurrent output.

[0119] The superposition of these two active adjustment mechanisms causes the equivalent impedance seen from the measurement port of the intelligent fusion terminal to exhibit drastic fluctuations over a very short period of time. This is essentially a pseudo-physical impedance (i.e., active impedance) that changes rapidly with the controller state.

[0120] Under these circumstances, the actual measured value of the fluctuation variance calculated by the system will show a significant surge, reaching or exceeding the passive physical branch identification threshold. Based on this, the intelligent fusion terminal determines that the currently extracted impedance phase angle change trajectory not only contains the actual physical fault impedance information but also includes interference information from the dominant inverter active control strategy. If the system continues to rely on the contaminated impedance phase angle for direction calculation, it will inevitably arrive at conclusions contradicting the actual physical facts, leading to serious protection malfunctions.

[0121] Therefore, adhering to the highest safety principle of ensuring no malfunction in power grid protection, the intelligent fusion terminal proactively cuts off the local direction determination data stream output at this moment, forcibly abandoning the output direction determination result. Subsequently, the intelligent fusion terminal automatically adjusts its operating mode, triggers a degraded protection strategy, packages and uploads the abnormal information of locally sensed voltage and current effective values ​​exceeding limits and the node's rejection status flag, and sends a request to a higher-level regional coordination terminal. Relying on the regional coordination terminal to use the global source-grid-load topology map to perform large-scale multi-terminal differential or multi-point topology reasoning, the global fault location is completed.

[0122] Overall, the technical solution described in this embodiment addresses the significant deficiency of existing high-frequency injection line selection technology in terms of insufficient anti-interference capability in practical power grid applications, and proposes a multi-dimensional dynamic anti-interference identification framework. Compared with existing technical solutions that use a fixed single frequency for blind detection and lack the ability to distinguish active / passive impedance physical properties, the dynamic impedance baseline model and adaptive dual-frequency orthogonal characteristic detection signal synthesis mechanism constructed in this embodiment enable the detection signal to have an advanced self-healing capability that actively avoids strong noise backgrounds.

[0123] More importantly, by introducing fluctuation variance discrimination logic based on impedance phase angle change trajectories, the system, for the first time at the edge computing level, possesses a deep physical cognition capability to identify passive faults in physical media and active disturbances in power electronic equipment. While ensuring accurate location of real high-resistance grounding faults, a safety degradation and phasing mechanism based on interference degree quantification is established. This scheme significantly improves the identification accuracy and operational reliability of complex multi-source distribution networks facing high-penetration power electronic equipment access conditions, especially when dealing with weak fault characteristic boundary conditions, demonstrating extremely broad engineering application prospects and practical promotion value.

[0124] Example 3:

[0125] In the actual operation and fault evolution of distribution networks, when a severe phase-to-phase metallic short circuit or high-current ground fault occurs, extremely strong transient electromagnetic pulses are instantly generated at the fault point and its surrounding cables. This high-energy electromagnetic radiation and the accompanying sharp rise in ground potential can easily cause severe physical layer interference to the optoelectronic transceiver modules inside the primary and secondary integrated ring main unit, as well as the externally laid fiber optic communication links or wireless communication modules. This interference manifests as severe packet loss, a surge in bit error rate, or even a brief physical paralysis of the communication link. In such extreme physical scenarios, the downstream terminals within the fault area may have accurately identified the fault and successfully driven their respective circuit breakers to complete the physical tripping action, effectively isolating the short-circuit fault.

[0126] However, due to the failure of the aforementioned communication channel, the trip success feedback signal sent by the lower-level terminal to report the completion status of the action was lost or severely delayed during network transmission, failing to reach the intelligent fusion terminal at the boundary of the consensus fault area on time. According to conventional timer logic, the upper-level intelligent fusion terminal at the boundary would determine that the lower-level node had failed to effectively clear the fault after the timer expires, and then blindly activate backup protection to perform an over-level trip. This failure of the anti-over-level blocking logic due to reliance solely on communication signals directly causes large-scale, unwarranted power outages in non-faulty areas, severely reducing power supply reliability.

[0127] To overcome the technical challenge of the disconnect between communication and physical state, this embodiment constructs a local redundancy verification mechanism that transcends the communication layer and directly delves into the essence of changes in electrical physical quantities. As a further in-depth extension and safety redundancy design of the above technical solution, this embodiment focuses on solving the problem of protection logic malfunction caused by communication channel failure in distribution networks under extreme physical conditions, and elaborates in detail the engineering implementation mechanism of the channelless local physical verification step.

[0128] Optionally, when the intelligent fusion terminal located at the boundary of the consensus failure zone fails to receive the successful trip feedback signal after the timer expires, before generating the circuit breaker trip command to drive the circuit breaker of its associated ring network cabinet to trip, it also embeds a channelless local physical verification step. In the logic control sequence of the system's central processing unit, the system interrupt service routine triggered by the timer expiration is no longer directly attached to the physical trip execution module, but is forcibly redirected to a newly added verification-level intermediate state machine. The role of this intermediate state machine is to force the system to find objective evidence of whether the lower-level circuit breaker has acted from the real physical changes in energy flow within the blind zone of information flow interruption, thereby avoiding reckless tripping decisions due to the lack of a single piece of communication information.

[0129] For example, the channelless local physical verification step specifically includes: when the timer expires, the intelligent fusion terminal starts and enters a local physical feature observation window of a preset duration. When the main frequency count value of the timer reaches the set overflow threshold and the specific flag bit of the communication receive buffer is still empty, the real-time operating system of the intelligent fusion terminal immediately allocates the highest priority computing resources and opens a strictly defined time window, namely the local physical feature observation window.

[0130] This preset duration is typically set to an extremely short timeframe of five to ten milliseconds. This range is limited because the process from the separation of the main contacts of the physical circuit breaker and the extinction of the arc to the sudden change in the system's electrical quantities has a specific inertial time constant. Five to ten milliseconds can fully cover the physical transient process of current decay and voltage recovery for feature extraction, while also being extremely short, preventing excessive delays in the timeliness of backup protection due to the introduction of observation mechanisms, thus ensuring the thermal stability and safety of the power grid equipment when a failure to operate actually occurs.

[0131] Specifically, within the local physical characteristic observation window, the intelligent fusion terminal extracts three-phase current data and bus voltage data from local measurement points, and calculates the current attenuation characteristic slope and voltage recovery characteristic slope, respectively. Upon entering this observation window, the high-precision analog-to-digital conversion channel inside the intelligent fusion terminal operates at high speed continuously. Three-phase current data is acquired through an electronic current transformer installed on the primary side of the ring main unit, and bus voltage data is acquired through an electronic voltage transformer. These analog electrical signals, after preliminary processing by a low-pass anti-aliasing filter, are converted into discrete digital sampling sequences and stored in a circular data buffer. To quantify and extract the transient change trend characterizing the physical break state from these discrete sequences, the digital signal processing core of the intelligent fusion terminal needs to perform discrete differential operations to calculate the current attenuation characteristic slope and voltage recovery characteristic slope, respectively.

[0132] It should also be noted that the physical meaning of the aforementioned current decay characteristic slope lies in quantifying the severity of fault current dissipation, and its specific calculation logic is implemented through the following first formula:

[0133] ;

[0134] In the formula, variables Represents the slope of the current decay characteristic calculated by the central processing unit of the intelligent fusion terminal; variable This represents the current amplitude of the current sampling point acquired by the intelligent fusion terminal within the local physical feature observation window; variable This represents the current amplitude of the preceding sampling point immediately before the current sampling point, extracted from the circular data buffer; variable This represents the sampling time interval that is strictly aligned between the current sampling point and the previous sampling point. According to this algorithm, the current decay characteristic slope is the ratio of the difference between the current amplitude at the current sampling point and the current amplitude at the previous sampling point to the sampling time interval. In actual power grid physical interruption processes, when the downstream circuit breaker successfully clears the fault, the short-circuit current path is physically blocked. Due to the rapid release and consumption of residual magnetic field energy within the system's equivalent inductance, the current waveform will exhibit a non-smooth, precipitous drop. At this time, the current amplitude at the current sampling point will be much smaller than the current amplitude at the previous sampling point, and the difference between the two is a very large negative number. Consequently, the calculated current decay characteristic slope will exhibit a deeply negative value with significant characteristics.

[0135] Similarly, the physical meaning of the voltage recovery characteristic slope mentioned above lies in quantifying the rate at which the system bus voltage is re-established after being pulled away from the short circuit point. Its specific calculation logic is implemented through the following second formula:

[0136] ;

[0137] In the formula, variables Represents the slope of the voltage recovery characteristic calculated by the intelligent fusion terminal; variable This represents the voltage amplitude of the current sampling point acquired by the intelligent fusion terminal within the local physical feature observation window; variable This represents the voltage amplitude of the preceding sampling point that is immediately adjacent to and earlier than the current sampling point in the time series; variable This also represents the preset discrete sampling time interval.

[0138] According to this algorithm, the voltage recovery characteristic slope is the ratio of the difference between the voltage amplitude at the current sampling point and the voltage amplitude at the previous sampling point to the sampling time interval. In the actual physical environment of a distribution network, during a fault, the large short-circuit current flowing through the system's equivalent impedance causes a severe drop in bus voltage. The moment the downstream node successfully disconnects the short-circuit current loop, this huge voltage loss factor disappears instantly, and the bus voltage recovers rapidly with the support of the grid's electromotive force. Therefore, the voltage amplitude at the current sampling point will be significantly greater than the voltage amplitude at the previous sampling point, and the difference between the two is a very large positive number. The calculated voltage recovery characteristic slope will then exhibit a steep positive slope.

[0139] like Figure 6 This figure objectively presents the physical verification process by which an intelligent fusion terminal verifies the on / off status of lower-level nodes by capturing sudden changes in electrical energy flow under extreme communication channel failure conditions. The horizontal axis of the figure represents the sampling time in milliseconds, covering an evolution period from 0 to 20 milliseconds; the left vertical axis represents the current amplitude in per-unit values; and the right vertical axis represents the voltage amplitude in per-unit values.

[0140] In the curve shape and color distribution displayed in the graph, the blue solid line represents the transient waveform of the current amplitude, and the red solid line represents the transient waveform of the voltage amplitude. In the figure, before the 10th millisecond, the distribution network system is in a short-circuit fault state, the current amplitude is maintained at a high short-circuit level of 5 per unit, and at the same time the bus voltage is pulled down to a low fault level of 0.2 per unit.

[0141] At the 10th millisecond, when the downstream circuit breaker successfully clears the fault, the intelligent fusion terminal enters a local physical characteristic observation window with a set duration of 5 to 10 milliseconds. Within this observation window, the blue current curve exhibits a precipitous drop in waveform, with its amplitude rapidly decaying towards zero. The current decay characteristic slope calculated from this is a deeply negative value with significant characteristics, satisfying the condition of being less than the preset negative current interruption threshold.

[0142] Simultaneously, the red voltage curve exhibits a steep voltage rebound waveform transformation, with its amplitude rapidly recovering to the normal rated level of 1 per unit. The voltage recovery characteristic slope calculated from this is a steep positive value with significant characteristics, satisfying the condition of being greater than the preset positive voltage threshold.

[0143] The simultaneous occurrence and cross-verification of this physical phenomenon of a sharp drop in current and a rapid rebound in voltage within the local physical characteristic observation window provides objective physical evidence to the upper-level intelligent fusion terminal at the boundary that the main contacts of the lower-level circuit breaker have been substantially separated. This enables the system to trigger the anti-maloperation interception logic and cancel the circuit breaker tripping command, avoiding the risk of cascading tripping caused by the loss of a single successful communication tripping feedback signal. This effectively enhances the reliability and fault tolerance of adaptive fault isolation decision-making.

[0144] For example, after calculating the above two characteristic slopes, the system immediately enters a strict dual threshold condition discrimination logic branch. If the current attenuation characteristic slope is less than the preset negative current interruption threshold and the voltage recovery characteristic slope is greater than the preset positive voltage recovery threshold, the intelligent fusion terminal determines that the lower-level node has successfully cleared the fault at the physical level, and then triggers the anti-maloperation interception logic, forcibly cancels the generation of the circuit breaker trip command, blocks the tripping circuit of the circuit breaker of the ring network cabinet, and generates a communication channel failure alarm for the lower-level node and uploads it to the regional coordination terminal.

[0145] In this discrimination logic, the preset negative current interruption threshold is a negative critical value set based on the decay time constant of the circuit breaker's ultimate breaking current under the maximum short-circuit capacity of the distribution network. When the calculated current decay characteristic slope is numerically even smaller than this negative current interruption threshold, it means that the current drop is extremely drastic, perfectly consistent with the physical phenomenon of forced arc extinction of a vacuum circuit breaker. Simultaneously, the preset positive voltage recovery threshold is a positive critical value set based on the transient recovery voltage rise rate determined by the short-circuit impedance and distributed capacitance of the main transformer in the distribution network.

[0146] When the calculated voltage recovery characteristic slope is greater than the forward voltage recovery threshold, it means that the voltage is in the process of rapid rebound. Only when the two physical phenomena of a sharp drop in current and a rapid rebound in voltage occur simultaneously and corroborate each other within the local physical characteristic observation window can the intelligent fusion terminal have reliable physical evidence to confirm that the main contacts of the downstream circuit breaker have substantially separated.

[0147] Upon confirming this physical fact, the intelligent fusion terminal immediately triggers the anti-maloperation interception logic. This interception logic clears the trip command execution queue originally intended for the operating system at the software level, and sends a blocking signal to the drive output control board via a general-purpose input / output interface at the hardware level, cutting off the drive power to the tripping thyristor or relay, thereby forcibly canceling the generation of the circuit breaker trip command and effectively blocking the tripping circuit of the associated ring main unit circuit breaker.

[0148] Through this series of interception actions based on the actual physical state, the upper-level intelligent converged terminal successfully avoided a cascading trip that would otherwise occur due to the loss of the successful feedback signal for the communication trip. Subsequently, given the fact that the physical state was normal but the communication state was abnormal, the data encapsulation module of the intelligent converged terminal would construct a specific alarm message format to generate a communication channel failure alarm for the lower-level node. This alarm information would be packaged and uploaded to the regional coordination terminal by the security protocol layer during the interval when the communication environment returned to normal or through redundant wireless channels, to guide maintenance personnel to conduct targeted troubleshooting of the damaged communication links.

[0149] Optionally, another logical branch executed by the system is designed to handle real equipment failure conditions. If the current decay characteristic slope is greater than or equal to the negative current interruption threshold, it is determined that the lower-level node has experienced a real mechanical failure to operate. The intelligent fusion terminal releases and executes the step of generating the circuit breaker trip command to drive the circuit breaker of the associated ring network cabinet to trip. Under this condition, the calculated current decay characteristic slope fails to fall below the set negative current interruption threshold, which means that the huge short-circuit current waveform does not exhibit the cliff-like dissipation characteristic unique to the breaking process, but maintains a smooth short-circuit steady-state fluctuation or an extremely slow amplitude decay. This electrical phenomenon clearly points to an extremely dangerous physical fact: the circuit breaker of the lower-level node has failed to separate its main contacts due to serious mechanical or physical hardware failures such as jammed operating mechanism, burnt-out trip coil, or air leakage in the arc extinguishing chamber, or the contacts remain in an arc re-breakdown state after separation.

[0150] Faced with the continuous injection of short-circuit energy caused by such mechanical failure to operate, the distribution network system faces the direct threat of equipment thermal breakdown and even fire. At this point, due to the lack of physical evidence to confirm the tripping action, the intelligent fusion terminal cancels the expectation of anti-level blocking and removes all interception constraints. The system operation core immediately releases the previously suspended action permissions and directly executes the action logic to generate the circuit breaker tripping command. A high-level drive pulse is precisely delivered to the power amplification device in the operating circuit, thereby driving the circuit breaker of the corresponding ring main unit to trip. The circuit breaker mechanism of the corresponding ring main unit instantly releases the energy stored in the spring, forcibly cutting off the short-circuit current path and completing the cascading backup isolation protection of the system backbone, preventing the widespread spread of fault energy.

[0151] In summary, considering the current state of distribution network automation technology, traditional adaptive fault isolation schemes generally suffer from a significant architectural flaw. Existing technologies primarily rely on Ethernet-based remote control protocols or message exchange mechanisms for general-purpose substation events to achieve logical interlocking and timing coordination between nodes. This state confirmation mechanism, which heavily depends on digital communication links, is particularly vulnerable to the severe electromagnetic interference associated with actual distribution network faults. When communication messages become congested or lost, traditional solutions often lack cross-validation fallback fault-tolerance mechanisms, either leading to blind, cascading tripping that causes uncontrolled expansion of the outage area, or falling into logical deadlock that causes protection systems to fail to operate, ultimately burning out upstream equipment.

[0152] The technical solution detailed in this embodiment introduces an extremely short local physical characteristic observation window and establishes a cross-verification algorithm based on the differential slope of current and voltage, thus supplementing the communication logic layer with a robust physical logic security baseline. This solution enables the intelligent fusion terminal to avoid making a single logical decision due to the lack of neighboring node information after losing state feedback from neighboring communication nodes. Instead, it can accurately reverse-engineer the mechanical disconnection at the remote end of the system by sensing the energy flow state change trajectory of the local port.

[0153] This technical framework, which deeply integrates information flow communication verification with energy flow physical verification, effectively compensates for the blind spots in relay protection under extreme communication interference conditions. The overall solution not only significantly improves the robustness of the adaptive fault isolation system in the face of complex electromagnetic environments and hardware failures, but also eliminates the risk of maloperation caused by unreliable communication from the underlying logic of the system control architecture. This ensures that even in extreme environments where multiple adverse factors such as high-impedance faults, high-current surges, and communication paralysis overlap, the distribution network can still execute the most precise and restrained fault isolation actions, maximizing the uninterrupted and stable power supply to loads in non-faulty areas.

[0154] Example 4:

[0155] like Figure 8 As shown, this embodiment discloses the specific implementation process of an adaptive fault isolation method based on a primary and secondary integrated ring main unit in a typical 10kV distribution network scenario. The physical architecture involved in this embodiment includes a regional coordination terminal deployed in the power supply zone and multiple primary and secondary integrated ring main units installed at each distribution node. Each ring main unit integrates an intelligent integrated terminal, a high-precision instrument transformer, and a vacuum circuit breaker. The terminals communicate with each other through a redundant optical fiber network.

[0156] 1. System initialization and dynamic source-load topology modeling stage.

[0157] During the initial stage of normal operation of the distribution network or the initial connection of new equipment, this embodiment performs system initialization. First, the regional coordination terminal obtains the registration parameters of distributed power sources and energy storage devices. In specific applications, when a photovoltaic power station, wind turbine generator, or energy storage battery is connected to the grid through a primary and secondary integrated ring network cabinet, its built-in intelligent control interface automatically reports key parameters such as equipment type, rated capacity, short-circuit current contribution multiple, and grid connection point location to the regional coordination terminal.

[0158] After receiving the aforementioned data, the regional coordination terminal constructs a dynamic source-grid-load topology map, using the substation outgoing line switch as the root node. This topology map not only includes traditional physical link connections but also marks the power direction and operating status of all active nodes (distributed power sources, energy storage) and passive nodes (controllable loads, ordinary users) in real time. When load fluctuations or significant changes in distributed power source output occur within the region, the regional coordination terminal updates this topology map in real time to ensure that the data basis for subsequent analysis remains highly consistent with the actual physical environment.

[0159] 2. Pre-fault rolling simulation and isolation scheme generation.

[0160] Based on the dynamic source-grid-load topology, the regional coordination terminal performs single-point fault simulation. During actual operation, the simulation algorithm simulates the scenario of short-circuit or ground faults occurring in each possible segment of the topology, and calculates the short-circuit current distribution and residual voltage distribution of each branch by combining the current penetration rate of distributed power sources (i.e., the ratio of total active power output to total load).

[0161] Through rehearsals, the regional coordination terminal generates a set of isolation scheme contingency plans, including isolation boundaries. This set of plans clarifies which ring main units (RNBs) should trip and which should perform interlocking operations at a specific fault point. Subsequently, the regional coordination terminal distributes these contingency plans to the corresponding intelligent converged terminals. This process ensures that the intelligent converged terminals have pre-stored corresponding response strategies before a fault occurs, significantly improving the response speed for subsequent on-site handling.

[0162] 3. Construction of local protection domain and delay calculation for intelligent fusion terminals.

[0163] Upon receiving the set of contingency plans, the intelligent fusion terminal generates a dynamic protection domain based on the local power source adjacency list and the isolation scheme contingency plan set. This dynamic protection domain defines the physical range monitored by the intelligent fusion terminal. Simultaneously, the intelligent fusion terminal calculates the basic adaptive delay in real time. This delay is not a fixed value but is dynamically adjusted based on the real-time penetration rate of distributed power sources within the current protection domain. For example, when the proportion of photovoltaic output within the protection domain increases, to prevent large-scale grid disconnection of inverters due to voltage drops during a fault, the intelligent fusion terminal automatically adjusts the basic adaptive delay to achieve faster fault clearing.

[0164] 4. Fault start-up and multimodal feature extraction.

[0165] When an anomaly occurs in the power grid, the intelligent fusion terminal initiates a fault handling process upon detecting a transient change signal in the distribution network. This transient change signal includes characteristics such as a sudden increase in power frequency current, a sudden drop in transient voltage, or an out-of-limit zero-sequence current.

[0166] After the processing is initiated, the intelligent fusion terminal dynamically switches directional elements based on the penetration rate of distributed power sources within the dynamic protection domain to calculate the fault direction. In practical applications, due to the current limiting effect of the controller on inverter-type distributed power sources during faults, the traditional power frequency characteristics may no longer be obvious. At this time, the intelligent fusion terminal will adaptively switch to the transient energy directional element or the harmonic impedance directional element, and generate a multi-power source direction code by analyzing the transient waveform or impedance changes in a specific frequency band at the initial stage of the fault. This code reflects the positional relationship (forward or backward) of the fault point relative to the ring main unit under various power source directions.

[0167] 5. Regional consensus voting and fault location.

[0168] After completing the direction calculation, the intelligent fusion terminal broadcasts the multi-power source direction code to terminals in adjacent communication layers for regional consensus voting. In a 10kV feeder network, 3 to 5 adjacent ring main unit terminals exchange their respective coded data in real time.

[0169] When a terminal within a certain area receives the encoding from a neighboring node, it makes a judgment according to a preset consensus algorithm. If, within a specific time window, more than a legally required proportion (e.g., more than two-thirds) of the terminals point to the same faulty segment, then when the ring network cabinet to which the terminal belongs is determined to be at the boundary of the consensus faulty area, the terminal identifies itself as the boundary node to perform the isolation action.

[0170] like Figure 7 This diagram visually illustrates the dynamic collaborative process of multiple terminals within adjacent communication layers conducting distributed voting and locking down fault boundaries after an anomaly occurs in the distribution network. The horizontal axis represents the communication interaction time step in milliseconds, covering communication interaction cycles from 1 to 10 milliseconds; the vertical axis represents the smart fusion terminal number in units, showing the five adjacent nodes participating in this regional consensus vote; the color gradient and the evolution of the matrix blocks in the diagram reflect the consensus state values ​​of the multi-power direction encoding of each node.

[0171] In terms of color distribution and state evolution in the graphic display, from the 1st millisecond to the 3rd millisecond, the matrix color blocks show a mixed distribution of dark blue representing the initial pending state and yellow-green representing the coding interaction state. This indicates that each intelligent fusion terminal is broadcasting to each other through the fiber optic network and receiving the multi-power direction coding data generated by each other. At this time, the proportion of the number of terminals pointing to the same faulty segment to the total number of votes has not yet reached the preset consensus threshold.

[0172] As the communication interaction time step progresses to the 4th millisecond, the matrix color blocks corresponding to the 5 terminal numbers in the figure all flip to dark red, representing the consensus lock state, and the state value is uniformly stabilized at 1.0. This means that more than two-thirds of the terminals have their direction codes clearly pointing to the same fault segment, and the system confirms it as a consensus fault area.

[0173] This time-step-based state matrix evolution diagram presents the execution logic of the distributed consensus mechanism in eliminating measurement deviations of a single node and realizing multi-source collaborative positioning. It shows that the terminal can autonomously confirm whether it is at the fault boundary through the convergence of state data within 4 milliseconds, thus providing a basis for subsequent start-up of the timer bound to the basic adaptive delay and for deciding to execute the blocking operation or generate the circuit breaker trip command.

[0174] 6. Adaptive and collaborative fault isolation execution.

[0175] After determining the boundary identity, the intelligent fusion terminal starts a timer bound to the basic adaptive delay. The timer's time constant is the adaptive result calculated in step 3. During this period, the intelligent fusion terminal listens for successful tripping signals from downstream terminals that are electrically closer within the fault area.

[0176] In actual operation scenarios, if the fault point is closer to the downstream terminal, the downstream terminal should trip first. If the boundary intelligent fusion terminal detects that the downstream terminal has successfully cleared the fault (by reporting the tripping status via a GOOSE message) before the timer resets to zero, it will perform a blocking operation on the ring main unit to maintain the current closed state, thereby minimizing the power outage range in non-faulty areas. Conversely, if no feedback is received from the downstream terminal before the timer expires, it is determined that the downstream terminal has failed to operate or the fault point is within the current section. A circuit breaker tripping command is then generated, driving the vacuum circuit breaker in the primary and secondary fusion ring main unit to perform the action, thus completing the adaptive fault isolation closed loop.

[0177] By implementing the above methods, this embodiment achieves rapid local response and precise isolation of distribution network faults while ensuring the flexibility of distributed power source access, effectively avoiding the risk of false tripping and failure to trip under large-scale DG access of traditional protection schemes.

[0178] Example 5:

[0179] Corresponding to the above embodiments, the present invention also proposes an electronic device.

[0180] like Figure 9The diagram shows a structural schematic of an electronic device according to the present invention. The electronic device 100 includes a processor 101 and a memory 103. The processor 101 and the memory 103 are connected, for example, via a bus 102. Optionally, the electronic device 100 may further include a transceiver 104. It should be noted that in practical applications, the transceiver 104 is not limited to one unit, and the structure of this electronic device 100 does not constitute a limitation on the embodiments of the present invention.

[0181] Processor 101 may be a CPU, a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, transistor logic device, hardware component, or any combination thereof. It may implement or execute the various exemplary logic blocks, modules, and circuits described in connection with this disclosure. Processor 101 may also be a combination that implements computational functions, such as including one or more microprocessor combinations, a combination of a DSP and a microprocessor, etc.

[0182] Bus 102 may include a pathway for transmitting information between the aforementioned components. Bus 102 may be a PCI bus or an EISA bus, etc. Bus 102 may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 9 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0183] The memory 103 stores a computer program corresponding to the adaptive fault isolation method based on a primary and secondary fusion ring main unit according to the above embodiments of the present invention. This computer program is executed by the processor 101. The processor 101 executes the computer program stored in the memory 103 to implement the content shown in the aforementioned method embodiments.

[0184] Among them, electronic devices 100 include, but are not limited to: mobile terminals such as laptops and PADs (tablet computers) and fixed terminals such as desktop computers. Figure 9 The electronic device 100 shown is merely an example and should not be construed as limiting the functionality and scope of the embodiments of the present invention.

[0185] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An adaptive fault isolation system based on a primary and secondary integrated ring network cabinet, characterized in that, This includes regional coordination terminals and multiple intelligent converged terminals built into the primary and secondary converged ring network cabinets; The regional coordination terminal is used to obtain the registration parameters of distributed power sources and energy storage devices to construct a dynamic source-grid-load topology map, and to perform single-point fault simulation based on the dynamic source-grid-load topology map, generate a set of isolation scheme plans including isolation boundaries, and distribute them to the corresponding smart fusion terminal. The intelligent fusion terminal is used to generate a dynamic protection domain based on the local power supply adjacency table and the isolation scheme set, and to calculate the basic adaptive delay in real time. Upon detecting a transient change signal in the distribution network, a fault handling procedure is initiated. Directional elements are dynamically switched based on the penetration rate of distributed power sources within the dynamic protection domain to calculate the fault direction. Specifically, this includes: When there is no inverter-type distributed power source or the penetration rate of inverter-type distributed power source is lower than the preset first penetration rate threshold in the dynamic protection domain, the power frequency negative sequence and zero sequence directional elements are activated, and the fault direction is determined by the phase difference of the power frequency fault components. When the penetration rate of the inverter-type distributed power source is greater than or equal to the first penetration rate threshold and the fault current is higher than the preset first current multiple threshold, the transient energy direction element is activated to extract the transient energy flow direction within the fault initial time window to determine the fault direction. When the penetration rate of the inverter-type distributed power source is greater than or equal to the first penetration rate threshold and the fault current is lower than the first current multiple threshold, the harmonic impedance direction element is activated, and the fault direction is determined by injecting a high-frequency detection signal into the system and measuring the harmonic impedance change characteristics. This generates multi-power direction codes; The intelligent fusion terminal is also used to broadcast the multi-power direction encoding to terminals in adjacent communication layers for regional consensus voting. When it is determined that the ring network cabinet is at the boundary of the consensus fault area, a timer bound to the basic adaptive delay is started. During this period, by listening to the tripping action signal of the lower-level terminal that is closer in electrical distance within the fault area, it decides to perform a blocking operation on the ring network cabinet or generate a circuit breaker tripping command, thereby completing the adaptive fault isolation closed loop.

2. The system according to claim 1, characterized in that, The triggering mechanism for the regional coordination terminal to perform single-point-of-failure pre-simulation includes: A rolling rehearsal is performed according to a preset time period; or a full-scenario single-point fault rehearsal is triggered when the output change rate of the distributed power source in the dynamic source-grid-load topology exceeds the first preset threshold, the load change rate exceeds the second preset threshold, or the switching state of any node changes in the real-time monitoring. The isolation scheme set explicitly includes the target set of trip switches, the optimal islanding scheme, and source-grid-load coordinated control parameters for each single-point fault scenario.

3. The system according to claim 1, characterized in that, The multi-power direction encoding generated by the intelligent fusion terminal is a fixed-bit binary feature sequence, including: Multiple power direction feature bits and one fault type identifier bit; wherein each of the power direction feature bits corresponds strictly to a power node in the dynamic source-load topology diagram; When the calculated fault point is located between the ring main unit and the corresponding power supply node, the power direction feature bit is assigned the first logic state; when the fault point is located on the side of the ring main unit away from the corresponding power supply node, it is assigned the second logic state; the fault type identifier bit is used to distinguish between phase-to-phase short circuit faults and single-phase ground faults.

4. The system according to claim 1, characterized in that, The rules for regional consensus voting by the intelligent fusion terminal are as follows: The data packet carrying the multi-power direction code and fault start flag is sent to the terminal at the adjacent communication layer. If the number of adjacent terminals participating in receiving data packets reaches the minimum voting base, and the proportion of terminals pointing to the same segment as the faulty segment in the total number of votes exceeds the preset consensus threshold, then the segment is locked as a consensus faulty area. If the consensus threshold cannot be reached within the current communication layer, the voting scope will be expanded to the outer physical nodes step by step according to the dynamic source-network-load topology diagram until a consensus failure area is formed.

5. The system according to claim 1, characterized in that, The control logic for the intelligent fusion terminal to decide whether to perform a blocking operation on its associated ring network cabinet or generate a circuit breaker trip command is as follows: If the intelligent fusion terminal located at the boundary of the consensus fault area receives a successful tripping feedback signal from a lower-level terminal that is electrically closer within the fault area before the timer expires after starting the timer, the timer will be stopped and the tripping circuit of the circuit breaker of the ring network cabinet will be physically blocked. If the trip success feedback signal is not received after the timer expires, it is determined that the lower-level node has failed to effectively clear the fault, and then the circuit breaker trip command is generated to drive the circuit breaker of the ring network cabinet to trip. Simultaneously, an active current limiting command is sent to the distributed power source in the non-faulty area to limit its output current to within the preset current limiting multiple threshold.

6. The system according to claim 5, characterized in that, The intelligent fusion terminal also has built-in multi-power collaborative multi-level fail-to-operate backup protection logic: By synchronously extracting the circuit breaker auxiliary contact change status, fault current waveform continuity status and arc extinguishing signal in the cabinet as multiple feature criteria, the operation execution status of the circuit breaker in the ring network cabinet can be detected in real time. When a comprehensive determination indicates that the circuit breaker of the ring main unit has failed to operate, a failure-to-operate cascading instruction containing the fault level is broadcast to all directly adjacent power supply side terminals. The adjacent terminals that receive the failure-to-operate cascading instruction forcibly reduce their own basic adaptive delay according to a preset ratio in order to accelerate the execution of cascading backup isolation.

7. The system according to claim 1, characterized in that, After completing adaptive fault isolation, the system triggers a seamless islanded operation mode with source-grid-load coordination. Intelligent converged terminals located in non-faulty areas automatically invoke the optimal islanding scheme from the isolation scheme contingency plan set and disconnect the physical connection switch with the main network; The voltage and frequency control mode of the energy storage device is activated to establish the reference voltage and frequency of the islanded microgrid. Then, the power supply of the distributed power source and the load nodes at all levels is restored in sequence according to the preset safe load priority matrix. When the main grid voltage is detected to have recovered and the conditions for synchronous grid connection are met, the synchronous grid connection operation is automatically executed to restore the global power supply.

8. The system according to claim 1, characterized in that, The underlying communication and sampling hardware architecture of the intelligent fusion terminal includes: The built-in high-precision synchronous sampling module, which supports a precise time synchronization protocol, is used to control the global node sampling synchronization error within microseconds to ensure the data alignment accuracy of transient energy and harmonic impedance feature extraction. The built-in dual-redundant fiber optic bus communication interface is equipped with a priority scheduling algorithm, which sets the transmission priority of regional consensus voting data packets and refusal to move over level instruction data packets to be higher than that of regular remote monitoring data streams, ensuring that neighborhood interaction information is delivered within a preset communication delay threshold.

9. An adaptive fault isolation method based on a primary and secondary integrated ring network cabinet, characterized in that, The method, applied to a distribution network system comprising a regional coordination terminal and multiple intelligent converged terminals integrated into a primary and secondary converged ring network cabinet, includes: The regional coordination terminal obtains the registration parameters of distributed power sources and energy storage devices to construct a dynamic source-grid-load topology map, and performs single-point fault simulation based on the dynamic source-grid-load topology map to generate a set of isolation scheme plans including isolation boundaries and distribute them to the corresponding smart fusion terminal. The intelligent fusion terminal generates a dynamic protection domain based on the local power supply adjacency table and the isolation scheme set, and calculates the basic adaptive delay in real time. When the intelligent fusion terminal detects a transient change signal in the distribution network, it initiates a fault handling process. Based on the penetration rate of distributed power sources within the dynamic protection domain, it dynamically switches directional elements to calculate the fault direction. Specifically, this includes: When there is no inverter-type distributed power source or the penetration rate of inverter-type distributed power source is lower than the preset first penetration rate threshold in the dynamic protection domain, the power frequency negative sequence and zero sequence directional elements are activated, and the fault direction is determined by the phase difference of the power frequency fault components. When the penetration rate of the inverter-type distributed power source is greater than or equal to the first penetration rate threshold and the fault current is higher than the preset first current multiple threshold, the transient energy direction element is activated to extract the transient energy flow direction within the fault initial time window to determine the fault direction. When the penetration rate of the inverter-type distributed power source is greater than or equal to the first penetration rate threshold and the fault current is lower than the first current multiple threshold, the harmonic impedance direction element is activated, and the fault direction is determined by injecting a high-frequency detection signal into the system and measuring the harmonic impedance change characteristics. This generates multi-power direction codes; The intelligent fusion terminal broadcasts the multi-power direction code to terminals in adjacent communication layers to conduct regional consensus voting. When it is determined that the ring network cabinet is at the boundary of the consensus failure area, a timer bound to the basic adaptive delay is started. During the operation of the timer, the intelligent fusion terminal listens to the tripping action signal of the lower-level terminal that is electrically closer in the fault area, and decides to perform a blocking operation on the ring network cabinet or generate a circuit breaker tripping command, thereby completing the adaptive fault isolation closed loop.

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