Differential protection and adaptive reclosing device and method for new energy station power collection line

Abstract

This invention relates to the field of power system relay protection technology, and discloses a differential protection and adaptive reclosing device and method for collector lines in new energy power plants. The device includes first, second, third, and fourth line protection control units connected sequentially via optical fiber communication links to cover mixed areas of cables and overhead lines. The method involves the following steps: setting an identification code for each control unit, comparing the identification code values ​​to establish a master-slave relationship, and executing a master-slave bidirectional synchronization method to obtain synchronization sampling values; using the synchronization sampling values ​​to calculate the differential current of the line section and the differential current of the entire line, obtaining the differential action result of the entire line and the fault determination result of the section; and executing adaptive reclosing logic based on the results, initiating reclosing when the fault is determined to be a fault of the entire line and an overhead line section, and blocking reclosing when the fault is determined to be a fault of the entire line and a cable line section. This invention achieves accurate identification of the fault medium of mixed lines, avoiding the secondary short-circuit impact on the system caused by blind reclosing.

Description

Technical Field

[0001] This invention relates to the field of power system relay protection technology, specifically to differential protection and adaptive reclosing devices and methods for collector lines in new energy power plants. Background Technology

[0002] In the power collection networks of new energy power plants, the lines are typically laid using a mixed method of alternating cable and overhead lines. This mixed topology leads to differences in the fault mechanisms of different sections of the line. Overhead line faults are mostly caused by transient factors such as lightning flashovers, and the insulation performance is easily restored after the fault is cleared; while cable line faults usually originate from irreversible permanent damage such as insulation breakdown. Traditional relay protection devices typically use a single reclosing operation logic for the entire power collection feeder, which cannot identify the specific fault medium type. When permanent insulation breakdown occurs in a cable section, blindly performing a reclosing operation will cause the power grid to be subjected to a large-capacity short-circuit current again, causing secondary damage to transformers and other primary high-voltage equipment.

[0003] To accurately distinguish specific fault sections in the hybrid lines for differentiated control, a distributed protection system is required in the project. This system relies on control units deployed at each segment node for data exchange. Due to the long distances of the power collection lines, fiber optic communication transmission delays can cause inherent deviations in the sampling time references of each node. In a chain-topology network architecture, if nodes lack effective state constraints when performing master-slave clock alignment, the clock fluctuations generated by devices in intermediate nodes dynamically adjusting their sampling periods will be transmitted to and amplified at each level, causing oscillations in the entire network's communication and sampling references. Ultimately, this results in the multi-source data participating in differential calculations failing to achieve alignment at the same time segment.

[0004] Furthermore, cable sections in hybrid lines inherently possess significant distributed capacitance to ground. During steady-state operation and transient processes caused by faults outside the designated area, capacitive leakage current can lead to a noticeable imbalance in current across the line. Conventional differential protection logic lacks an effective compensation mechanism for this characteristic, making it prone to malfunctions due to current difference exceeding limits. Existing fault diagnosis strategies also rely heavily on local calculations within a single interval. In complex field electromagnetic environments, if the underlying fiber optic data link experiences temporary distortion or individual sampling point misalignment, single-dimensional judgment can easily result in misjudgment of fault location, lacking global cross-validation to intercept erroneous protection commands caused by underlying anomalies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a differential protection and adaptive reclosing device and method for power collection lines in new energy power plants. It solves the problems of traditional reclosing strategies being unable to distinguish between mixed line fault media, leading to blind reclosing of permanent cable faults and causing secondary high current surges in the system, and the problems of distributed nodes in chain-networked systems being prone to step-by-step oscillations during clock synchronization, resulting in inaccurate alignment of sampling references.

[0006] To achieve the above objectives, the first aspect of the present invention provides a differential protection and adaptive reclosing device for the collection lines of new energy power stations, including a line protection control unit, wherein the line protection control unit includes a first line protection control unit, a second line protection control unit, a third line protection control unit and a fourth line protection control unit;

[0007] A substation is located outside the first line protection control unit, and a switching station is located outside the fourth line protection control unit. A first section of cable is connected between the first line protection control unit and the second line protection control unit; an overhead line is connected between the second line protection control unit and the third line protection control unit; and a second section of cable is connected between the third line protection control unit and the fourth line protection control unit. The first line protection control unit, the second line protection control unit, the third line protection control unit, and the fourth line protection control unit are connected sequentially via an optical fiber communication link; Both the first line protection control unit and the fourth line protection control unit are equipped with reclosing execution modules.

[0008] Furthermore, the first line protection control unit, the second line protection control unit, the third line protection control unit, and the fourth line protection control unit all include a signal acquisition module, an optical fiber differential protection module, and a command output module; The signal acquisition module is used to acquire current signals and voltage signals and generate sampled values; The instruction output module is used to output instructions to start reclosing or to block reclosing.

[0009] Furthermore, the first line protection control unit is provided with a first identification code, the second line protection control unit is provided with a second identification code, the third line protection control unit is provided with a third identification code, and the fourth line protection control unit is provided with a fourth identification code; The first identification code is greater than the second identification code, the second identification code is greater than the third identification code, and the third identification code is greater than the fourth identification code.

[0010] Furthermore, the fiber optic differential protection module is used to acquire the sampled value generated by the signal acquisition module, and is equipped with a forward data frame and a reverse data frame; The second line protection control unit forwards the forward data frame to the third line protection control unit. The forward data frame carries the sampled value of the second line protection control unit, the sampled value of the first line protection control unit, and the sampled value of the fourth line protection control unit. After receiving the positive data frame, the third line protection control unit replaces the original sampled value of the second line protection control unit in the positive data frame with its own sampled value, and forwards the sampled values ​​of the first line protection control unit and the fourth line protection control unit to the fourth line protection control unit. The third line protection control unit forwards the reverse data frame to the second line protection control unit. The reverse data frame carries the sampled value of the third line protection control unit, the sampled value of the first line protection control unit, and the sampled value of the fourth line protection control unit. After receiving the reverse data frame, the second line protection control unit replaces the original sampled value of the third line protection control unit in the reverse data frame with its own sampled value, and forwards the sampled values ​​of the first line protection control unit and the fourth line protection control unit to the first line protection control unit.

[0011] Furthermore, the fiber optic differential protection module is used to calculate the differential current of the line section and the differential current of the entire line, and to obtain the differential action result of the entire line and the fault determination result of the section. When it is determined that the differential action result of the entire line is a fault and the fault determination result of the section is a fault of the overhead line section, the reclosing execution module starts the reclosing; When it is determined that the differential action result of the entire line is a fault and the fault determination result of the section is a fault in the first section of the cable or a fault in the second section of the cable, the reclosing execution module blocks the reclosing.

[0012] The second aspect of this invention provides a differential protection and adaptive reclosing method for collector lines in new energy power plants, comprising the following steps: It provides substations, first line protection control units, first section of cable, second line protection control units, overhead lines, third line protection control units, second section of cable, fourth line protection control units, and switching stations; Connect the first line protection control unit to the substation, and connect the fourth line protection control unit to the switching station; A first identification code is set for the first line protection control unit, a second identification code is set for the second line protection control unit, a third identification code is set for the third line protection control unit, and a fourth identification code is set for the fourth line protection control unit; The sizes of the first identification code, the second identification code, the third identification code, and the fourth identification code are compared to obtain the size comparison result. The master-slave relationship between two adjacent line protection control units is determined by combining the size comparison result. The line protection control unit is controlled to collect current and voltage signals and generate sampled values; Based on the master-slave relationship, a master-slave bidirectional synchronization method is executed to synchronize the sampled values ​​and obtain synchronized sampled values. The differential current of the line section and the differential current of the entire line are calculated using the synchronous sampled values ​​to obtain the differential action results of the entire line and the fault determination results of the section. Based on the differential action results of the entire line and the fault determination results of the section, the reclosing execution module is controlled to start reclosing or block reclosing.

[0013] Furthermore, before acquiring the synchronized sample value, a bidirectional data forwarding step-by-step process is included: The second line protection control unit is controlled to forward positive data frames to the third line protection control unit; After receiving the positive data frame, the third line protection control unit replaces the original sampled value of the second line protection control unit in the positive data frame with its own sampled value and forwards it to the fourth line protection control unit. The third line protection control unit is controlled to forward reverse data frames to the second line protection control unit; After receiving the reverse data frame, the second line protection control unit replaces the original sampled value of the third line protection control unit in the reverse data frame with its own sampled value and forwards it to the first line protection control unit. During the forwarding process, both the forward data frame and the reverse data frame retain the sampled values ​​of the first line protection control unit and the fourth line protection control unit.

[0014] Furthermore, based on the master-slave relationship, a master-slave bidirectional synchronization method is executed to achieve sampling synchronization and obtain synchronized sample values, including: Based on the master-slave relationship, two adjacent line protection control units are respectively designated as the master and slave ends; The sampling time deviation between the two line protection control units is calculated by controlling the total round-trip delay of the master end and the slave end, as well as the inherent dwell time between receiving and transmitting within the hardware of the line protection control unit. When the sampling time deviation is determined to be greater than a preset synchronization threshold, the slave end is controlled to adjust the sampling time to achieve synchronization with the master end, so that the sampled value is converted into the synchronized sampled value; When the second line protection control unit or the third line protection control unit is in the sampling adjustment state as the slave end, the synchronous adjustment of the adjacent line protection control unit with an identification code smaller than that of the slave end is blocked; The preset synchronization threshold is the tolerance of the system sampling frequency and the phase angle error of the power grid frequency.

[0015] Furthermore, the differential current of the line section and the differential current of the entire line are calculated using the synchronously sampled values ​​to obtain the differential operation results of the entire line and the fault determination results of the section, including: The differential current between line sections is calculated using the synchronous sampling values. Combined with the ratio braking principle, a section fault action indicator is generated to determine whether there is an internal fault in this section, or whether there is no fault in this section, or whether it belongs to an external fault. The differential current across the entire line is calculated based on the current of the first line protection control unit and the current of the fourth line protection control unit. The differential action result across the entire line is generated. When it is determined that there is a fault in the macroscopic range of the entire line, the fault across the entire line is output as the differential action result across the entire line. When it is determined that no fault has occurred within the entire macroscopic range, the output "All lines are normal" is taken as the result of the differential action of the entire line. When it is determined that the internal fault has occurred in the section where the first cable segment is located or the section where the second cable segment is located, the fault in the first cable segment section or the fault in the second cable segment section is output as the fault determination result of the section. When it is determined that the internal fault has not occurred in the section where the first cable segment is located and the section where the second cable segment is located, but the internal fault has occurred in the section where the overhead line is located, the fault of the overhead line section is output as the fault determination result of the section. If the differential action result indicates a fault across the entire line, but within the same synchronization time tag window, the fault determination results for all independent intervals return a fault-free state, then the underlying data link is determined to be in a mismatch state, and a forced downgrade output of the fault signal for the unknown interval of the entire line is performed.

[0016] Further, based on the overall differential action result and the section fault determination result, the reclosing execution module is controlled to initiate reclosing or block reclosing, including: When it is determined that the differential action result of the entire line is a fault of the entire line and the fault determination result of the section is a fault of the overhead line section, the reclosing execution module is controlled to start reclosing. When it is determined that the differential action result of the entire line is a fault and the fault determination result of the section is a fault in the first section of the cable or a fault in the second section of the cable, the reclosing execution module is controlled to block the reclosing. If the results of the differential action of the entire line and the fault determination results of the section do not meet the above conditions for starting reclosing or blocking reclosing, the reclosing execution module is controlled to maintain the current state and not operate. When periodic data packet loss is detected in adjacent nodes and the duration exceeds the preset communication interruption threshold, it is determined that the optical fiber communication link has been interrupted, the differential protection action of the communication interruption interval is blocked, and the local backup protection module is activated. When a hardware-level fault occurs in the line protection control unit, the differential protection operation and reclosing of the line protection control unit with the fault are blocked. The preset communication interruption threshold is the sum of the time for five consecutive normal message exchange cycles in the fiber optic channel.

[0017] This invention provides a differential protection and adaptive reclosing device and method for the collector lines of new energy power plants. It has the following beneficial effects: 1. This invention obtains the differential action results of the entire line and the fault determination results of each section through the logic control unit, and executes differentiated strategies for different transmission media. When a fault is determined to occur in an overhead line section, the system initiates a reclosing procedure to eliminate transient faults such as lightning strikes and quickly restore grid-connected power generation. When a fault is determined to occur in the first or second section of the cable, the system identifies it as irreversible permanent damage and forcibly blocks reclosing, avoiding the secondary high-current short-circuit impact caused by blindly reclosing permanent cable faults, and protecting the safety of primary equipment such as transformers.

[0018] 2. This invention automatically establishes the master-slave relationship of all cascaded nodes in the network by pre-setting sequentially decreasing identification codes for each line protection control unit and based on numerical comparison results. It also dynamically adjusts the sampling time of the slave end using a master-slave bidirectional synchronization method, eliminating communication delay errors caused by long-distance fiber optic links without relying on an external satellite clock source. Simultaneously, a oscillation prevention mechanism that locks the synchronization adjustment of downstream nodes during sampling adjustment by intermediate nodes prevents clock fluctuations from being amplified at each stage in the chain topology, ensuring strict time reference consistency for data from all ends participating in differential calculations.

[0019] 3. This invention constructs a dual-track calculation architecture that combines independent interval differential and macroscopic full-line differential. It also introduces a capacitor current compensation phasor into the calculation formula of segmented interval differential current. This not only overcomes the unbalanced current interference caused by the long-distance distributed capacitance of the cable segment under transient and steady-state conditions, but also confirms the actual fault location through matrix cross-verification of full-line data and segmented data. When there is a mismatch between local data and global judgment, an unknown fault signal is forcibly output and the action is blocked, reducing the probability of protection maloperation caused by external faults or communication distortion. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the deployment structure of the differential protection and adaptive reclosing device for mixed overhead and cable lines of the present invention; Figure 2 This is a flowchart of the adaptive reclosing method of the present invention.

[0021] Among them, 1. Substation; 2. First line protection control unit; 3. First section of cable; 4. Second line protection control unit; 5. Overhead line; 6. Third line protection control unit; 7. Second section of cable; 8. Fourth line protection control unit; 9. Switching station; 10. Fiber optic communication link. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] See attached document Figure 1 , Figure 1 This is a schematic diagram of the deployment structure of a differential protection and adaptive reclosing device for mixed overhead and cable lines according to an embodiment of the present invention. The present invention provides a differential protection and adaptive reclosing device for the collector lines of new energy power plants, which may include: multiple line protection control units and an optical fiber communication link 10.

[0024] The line protection control unit includes a first line protection control unit 2, a second line protection control unit 4, a third line protection control unit 6, and a fourth line protection control unit 8.

[0025] The first line protection control unit 2 is connected to substation 1. The fourth line protection control unit 8 is connected to switching station 9.

[0026] A first section of cable 3 connects the first line protection control unit 2 and the second line protection control unit 4. An overhead line 5 connects the second line protection control unit 4 and the third line protection control unit 6. A second section of cable 7 connects the third line protection control unit 6 and the fourth line protection control unit 8.

[0027] The first line protection control unit 2, the second line protection control unit 4, the third line protection control unit 6, and the fourth line protection control unit 8 are connected sequentially via optical fiber communication link 10.

[0028] The first line protection control unit 2, the second line protection control unit 4, the third line protection control unit 6, and the fourth line protection control unit 8 all include a signal acquisition module, an optical fiber differential protection module, and an instruction output module.

[0029] The first line protection control unit 2 and the fourth line protection control unit 8 are equipped with reclosing execution modules. The reclosing execution module is used to perform the actions of initiating reclosing or blocking reclosing.

[0030] The signal acquisition module is used to acquire current and voltage signals and generate sampled values. The command output module is used to output commands to start or block reclosing. The fiber optic differential protection module is used to acquire the sampled values ​​generated by the signal acquisition module, calculate the differential current of the line section and the differential current of the entire line, and obtain the differential action results of the entire line and the fault determination results of the section.

[0031] See attached document Figure 2 , Figure 2 This is a flowchart of an adaptive reclosing method according to an embodiment of the present invention. The present invention provides a differential protection and adaptive reclosing method for collector lines in new energy power plants, which may include: S1: Set a first identification code for the first line protection control unit 2, a second identification code for the second line protection control unit 4, a third identification code for the third line protection control unit 6, and a fourth identification code for the fourth line protection control unit 8. Compare the sizes of the first, second, third, and fourth identification codes to obtain the size comparison result. Combine the size comparison result to determine the master-slave relationship between two adjacent line protection control units.

[0032] S2, the control line protection control unit collects the current and voltage signals of its local node to generate sampled values. Based on the established master-slave relationship, it executes a master-slave bidirectional synchronization method to synchronize the sampled values ​​and obtain synchronized sampled values. Each line protection control unit uses the fiber optic communication link 10 for bidirectional data forwarding level by level.

[0033] S3 uses synchronous sampling values ​​to calculate the differential current of the line section and the differential current of the entire line, and obtains the differential action results of the entire line and the fault judgment results of the section.

[0034] S4, based on the differential action results of the entire line and the fault judgment results of the section, controls the reclosing execution module to start reclosing or block reclosing.

[0035] Specifically, when the differential action result of the entire line is determined to be a fault of the entire line, and the fault determination result of the section is a fault of section 5 of the overhead line, the reclosing execution module is controlled to start the reclosing.

[0036] When the differential action result of the entire line is determined to be a fault of the entire line, and the fault determination result of the section is a fault of section 3 of the first cable section or a fault of section 7 of the second cable section, the reclosing execution module is controlled to block the reclosing.

[0037] In this embodiment, refer to the appendix Figure 2 , Figure 2 This is a flowchart of an adaptive reclosing method according to an embodiment of the present invention. To establish a unified time reference in a distributed optical fiber communication network, it is necessary to establish the master-slave status of each communication node during the power-on initialization phase of the device system. Based on the above requirements, this embodiment elaborates on the identification code configuration and master-slave relationship establishment steps in the adaptive reclosing method. In a general microcomputer protection network topology, the election of the master-slave relationship usually relies on a preset unique identifier for the node. Considering the specific scenario of a hybrid collector line, the specific implementation process can be divided into the following sub-steps: S101, the relative positions of each protection node are determined based on the system hardware deployment topology. Since the power collection lines of new energy power plants have a fixed route from the power source side to the load side, and the segmentation directly determines the attributes of the fault section, as a preferred approach, the first line protection control unit 2 connecting to substation 1 is designated as the head unit, and the fourth line protection control unit 8 connecting to switchgear 9 is designated as the tail unit. The second line protection control unit 4 and the third line protection control unit 6 are deployed sequentially along the route from substation 1 to switchgear 9 as intermediate node units.

[0038] S102, assign and set a unique identification code for each line protection control unit. This identification code is represented by an integer data parameter stored in the non-volatile memory of the line protection control unit. The operator pre-sets a first identification code for the first line protection control unit 2, a second identification code for the second line protection control unit 4, a third identification code for the third line protection control unit 6, and a fourth identification code for the fourth line protection control unit 8. To reflect the timing priority of the network topology, the integer values ​​of each identification code are set to decrease sequentially along the line direction. The specific value setting results must satisfy: the first identification code is greater than the second identification code, the second identification code is greater than the third identification code, and the third identification code is greater than the fourth identification code. The reason for using the decreasing rule here is that the first node closer to the substation 1 side is usually directly connected to the main network and has a higher time reference accuracy. Assigning it the largest value to prioritize its establishment as the main node of the entire network is beneficial for aligning the distributed clock synchronization reference to the high-precision source.

[0039] S103, Interchange of identification code information between adjacent line protection control units. After the fiber optic communication link 10 is established, the instruction output module of each line protection control unit sends a communication initialization handshake message containing its own identification code parameters to the physically connected adjacent nodes. At the same time, the fiber optic differential protection module continuously receives communication initialization handshake messages from adjacent nodes, and after performing basic message integrity checks such as cyclic redundancy check, it parses and extracts the identification code values ​​of the adjacent nodes from them.

[0040] S104: Compare the sizes of the first, second, third, and fourth identification codes to obtain the size comparison result. Combine this result to determine the master-slave relationship between two adjacent line protection control units. The microprocessor inside the line protection control unit extracts the parsed adjacent node identification codes and performs a numerical comparison operation with the locally stored identification codes. In typical distributed systems, state determination needs to have algorithmic completeness, covering all possible comparison results. The logical determination process for the device's operating state uses the following calculations: ; In the formula, Characterizes the communication and synchronization status of the local line protection control unit; It represents the master state and instructs the local device to send synchronization control commands to the adjacent counterpart as a clock reference. It represents the state of the device at the end and indicates that the local device needs to adjust the sampling time in accordance with the adjacent device on the other side. The representation state configuration is abnormal; Represents the locally preset identification code integer value; Represents the integer value of the received neighbor node identification code.

[0041] Considering practical engineering applications, the identification code parameter is typically selected as unsigned integer data, with its value range set to be greater than zero and less than a specific system upper limit. Furthermore, the preset value for each device on a single line must ensure global uniqueness. Based on the above judgment logic, when the comparison result shows that the local identification code value is greater than or less than the identification code value of the adjacent node, the adjacent ends successfully establish a master-slave collaborative working relationship. When the comparison result shows that the local identification code value is equal to the identification code value of the adjacent node, the judgment logic outputs an abnormal configuration status. The system will proactively block the differential protection action of this interval and report a configuration conflict alarm, thereby avoiding network instability caused by configuration errors.

[0042] Based on this logical rule, after the first line protection control unit 2 interacts with the second line protection control unit 4, the former is established as the master and the latter as the slave. Similarly, the second line protection control unit 4 is the master relative to the third line protection control unit 6, and the third line protection control unit 6 is the master relative to the fourth line protection control unit 8.

[0043] For the data processing of the microprocessor inside the line protection control unit, the read and write operations of the non-volatile memory, and the compilation and decoding mechanism of the underlying messages of the optical fiber communication link, those skilled in the art can refer to the existing hardware design specifications of microcomputer protection devices and related communication protocol standards. The underlying software and hardware implementation methods are well-known technologies in this field and will not be elaborated here.

[0044] In this embodiment, refer to the appendix Figure 2 After completing the master-slave architecture of each node device, the distributed protection network faces the engineering challenges of eliminating communication delays caused by spatial distance and constructing a panoramic data interaction system. Based on the above technical requirements, this embodiment elaborates on the sampling synchronization mechanism and data transmission strategy in the adaptive reclosing method. The specific implementation process is divided into the following sub-steps: S201 controls each line protection control unit to synchronously acquire current and voltage signals of the lines at their respective nodes through internal signal acquisition modules, and generates discrete sampled values ​​through analog-to-digital conversion. Because the long-distance fiber optic medium in the hybrid power collection lines of new energy power plants causes objective transmission delays in signal propagation, directly comparing sampled values ​​generated by remote nodes that lack a unified timestamp will result in phase errors and induce differential protection malfunctions. Therefore, after acquiring initial sampled values, adjacent nodes must implement a master-slave bidirectional synchronization method to achieve sampling synchronization, thereby obtaining synchronized sampled values ​​with a consistent time base.

[0045] S202, based on the established master-slave relationship, two adjacent line protection control units are respectively designated as the master and slave. Before performing the synchronization calculation, the system constructs a measurement channel according to the standard network time synchronization principle. The master and slave continuously exchange communication messages carrying timestamps to measure the total round-trip delay and the inherent dwell time between reception and transmission within the line protection control unit hardware. The master sends a probe frame to the slave at the transmission time determined by its local clock. The slave records the arrival time, processes it internally, and sends an acknowledgment frame. The master records the reception time of this acknowledgment frame. After obtaining the relevant time parameters using the high-precision timer inside the microprocessor, the sampling time deviation between the two line protection control units is calculated. This calculation process is expressed by the following mathematical formula: ; In the formula, The value representing the sampling time deviation between the slave end and the master end; Represents the local absolute time at which the master sends the probe frame; Represents the local absolute time of receiving the probe frame from the slave end; Represents the local absolute time at which the response frame is sent from the slave end; This represents the local absolute time when the master end receives the acknowledgment frame. The preorder term in the numerator represents the total round-trip delay of the message in the communication link, while the postorder term represents the hardware dwell time of the message between reception and transmission within the slave end. The constant in the denominator is two, based on the assumption that the optical fiber transceiver channels are coaxial and of equal length, i.e., assuming symmetrical bidirectional propagation time of the optical signal.

[0046] To avoid clock misalignment caused by extreme interference from single communication jitter, as a preferred approach, the master device extracts sampling time deviation data from multiple consecutive normal interaction cycles and uses a moving average filtering algorithm for weighted calculation to obtain a smoothed expected deviation value. Simultaneously, to ensure algorithm completeness, a maximum communication timeout threshold is set. If the difference between the local absolute time of the received response frame and the local absolute time of the sent probe frame exceeds this threshold, the interaction message is deemed invalid and the data set is discarded.

[0047] After obtaining the smoothed deviation value, the master end sends it to the slave end. The slave end determines whether the absolute value of the deviation at that sampling time is greater than a preset synchronization threshold. In this embodiment, the preset synchronization threshold depends on the tolerance of the system sampling frequency and the phase angle error of the power grid frequency, and its value range is usually set at the microsecond level. When it is determined that the absolute value of the deviation is greater than the preset synchronization threshold, the microprocessor inside the slave end actively adjusts its own sampling time to achieve synchronization with the master end by dynamically adjusting the trigger period of the analog-to-digital converter hardware timer, thereby converting its own sampled value into a synchronized sampled value with a consistent timing reference.

[0048] S203 implements a cascaded anti-oscillation protection mechanism for intermediate nodes. For hybrid collector line chain topologies, multiple line protection control units form a multi-level cascade structure. When a device at an intermediate node (such as the second line protection control unit 4) acts as a slave relative to its upstream counterpart, if its own clock is not aligned with the global reference, the synchronization reference signal sent downstream will be in a fluctuating state. To prevent this instability from amplifying at each level and causing clock oscillations across the entire network, the system is configured with a blocking control command. When the line protection control unit at an intermediate node is in a sampling adjustment state adjusting the analog-to-digital conversion period as a slave, its command output module sends a blocking flag message via optical fiber to the adjacent downstream line protection control unit whose identification code is less than its own. Upon receiving this message, the downstream node actively blocks its own synchronization adjustment process, maintaining the current sampling period unchanged. Only after the upstream node leaves the sampling adjustment state and locks a stable clock reference can the downstream node resume dynamic synchronization adjustment.

[0049] S204, each line protection control unit utilizes fiber optic communication link 10 to perform bidirectional data forwarding at each level. Conventional panoramic data acquisition relies on high-bandwidth star-shaped communication networks, which are costly to construct. This embodiment, based on the decreasing pattern of the identification code, designs a step-by-step forwarding mechanism with self-updating and retention features.

[0050] Along the direction of decreasing identification code (i.e., downstream from the head of substation 1 to the tail of switching station 9), the subunit forwards forward data frames according to a preset communication time slot. For example, when the second line protection control unit 4 forwards data to the third line protection control unit 6, the forward data frame carries the synchronization sample value of the second line protection control unit 4 itself, as well as the synchronization sample value of the first line protection control unit 2 (head end) obtained from upstream. After receiving the forward data frame, in order to ensure that the total message length of the link transmission does not expand with the increase of nodes, the internal processor of the third line protection control unit 6 replaces the original sample value of the second line protection control unit 4 in the data frame with its own synchronization sample value, while keeping the sample value of the first line protection control unit 2 at the head end unchanged, and continues to forward it to the fourth line protection control unit 8 (tail end).

[0051] Similarly, along the direction of increasing identification code (i.e., upstream from the tail end of switchgear 9 to the head end of substation 1), the subunit forwards the reverse data frame to its upstream node. When the downstream third line protection control unit 6 sends a reverse data frame to the second line protection control unit 4, the message carries its own synchronization sample value and the synchronization sample value of the fourth line protection control unit 8 (tail end). After receiving it, the second line protection control unit 4 also replaces the data of the adjacent third line protection control unit 6 with its own data and forwards it upstream to the head end while retaining the original tail end data.

[0052] Ultimately, all nodes in the entire link can simultaneously acquire data from the opposite unit within their local interval, as well as global data from the first and last units. Before executing subsequent algorithms, each node device needs to perform time window alignment based on the absolute timestamps carried in the multi-source data packets to ensure that the first, last, and opposite data involved in the calculation all belong to the same operating condition of the power grid at that time, thus laying the foundation for accurate differential calculation. For the implementation details of the encapsulation and decapsulation process of communication packets and the cyclic redundancy check mechanism, those skilled in the art can refer to the microcomputer protection communication specification. Its underlying encoding and scheduling methods are well-known technologies in this field and will not be elaborated here.

[0053] In this embodiment, refer to the appendix Figure 1 and attached Figure 2 After exploring the flow and alignment mechanisms of multi-source data, the key to the core logic design of the device lies in how to accurately capture faults using data belonging to the same operating condition time segment. To accurately clear faults in hybrid collector lines and provide a reliable basis for subsequent adaptive reclosing operations, the system adopts a dual-track differential calculation logic based on Kirchhoff's current law. In an ideal closed-node physical model, the vector sum of the currents flowing into and out of the interval should approach zero; once an internal short circuit occurs, this vector sum will change abruptly. Based on this general principle, the specific implementation process is divided into the following sub-steps: S301 uses synchronized sampled values ​​aligned with time tags to calculate the differential current of each line segment, and generates the section fault determination result by combining the ratio braking principle. As a preferred method, the microprocessor of the line protection control unit extracts the synchronous current phasor of two adjacent nodes at the same moment. Because cable sections in new energy hybrid power collection lines objectively have large distributed capacitance to ground, the currents collected on both sides have a difference due to capacitor leakage current. If traditional differential criteria are directly introduced, large transient unbalanced currents are easily generated when voltage drops occur due to external faults, thus inducing protection maloperation. Based on the above objective phenomena, the calculation logic must introduce a capacitor current compensation term on the basis of the basic phasor sum. For any line section, the calculation formula for its characteristic parameters is as follows: ; ; In the formula, Characterizing the first The effective value of the differential current between the line sections in each section; Characterizing the first The effective value of the braking current of the line section in each interval; Characterizes the synchronously sampled current phasor measured at the first node of this interval; Characterizes the synchronously sampled current phasor measured at the end node of this interval; Characterizing the first Capacitive current compensation phasors for each interval; The system identifier number representing the interval.

[0054] The purpose of introducing a capacitor current compensation phasor is to eliminate the influence of distributed capacitance under steady-state and transient conditions. Its value can be calculated from the voltage phasor of the relevant interval and the measured capacitive reactance parameters of the line. A constant denominator of two is introduced in the formula when calculating the braking current to obtain the arithmetic mean of the current amplitudes on both sides, thereby smoothing the severe impact of transient changes on the system's braking quantity. Considering the characteristics of the microprocessor's underlying architecture, the division operation for the constant two is directly replaced by an arithmetic right shift instruction to avoid the risk of division-by-zero overflow in the underlying calculation. Simultaneously, considering the hardware limitations of the analog-to-digital converter chip in terms of noise drift under extremely low signal input, a small amount of dead-time filtering logic needs to be set. When the measured synchronous sampling current phasor amplitude is lower than the hardware conversion accuracy limit, it is forcibly returned to zero to prevent accumulated noise from being misjudged in subsequent multidimensional calculations.

[0055] After extracting the cleaned feature parameters, the microprocessor generates the interval fault action identifier based on the following logical equation: ; In the formula, Characterizing the first The fault determination result of each interval is assigned a value of one to indicate that there is an internal fault in this interval, and a value of zero to indicate that there is no fault in this interval or that it is an external fault. Characterizing the first Differential starting current threshold for each interval; Characterizing the first The ratio braking coefficient for each interval; The AND operation represents the logical operation, which requires both conditions to be met simultaneously. It represents other cases, i.e., the values ​​when the above conditions are not met.

[0056] The specific value of the differential starting current threshold is set based on the uncompensated unbalanced steady-state current of the interval under maximum operating conditions to avoid background errors under normal operating conditions. The ratio braking coefficient is constrained to a range of 0.3 to 0.7. Its technical purpose is to dynamically raise the action boundary proportionally according to the rise of the through-current external fault current, thereby resisting local data distortion caused by the magnetic circuit saturation of the current transformer. By traversing and calculating the data models of the first cable section 3, the overhead line 5, and the second cable section 7, the system can independently output the interval fault judgment results of the three isolated areas.

[0057] S302, after completing the refined scanning of the segmented sections, it is particularly necessary to construct a multi-dimensional redundancy and fault-tolerance mechanism to prevent local protection blind spots caused by the hardware failure of a single communication node. In this embodiment, while performing segmentation determination, synchronous sampling values ​​from both ends of the entire line are extracted in parallel, the total differential current of the entire line is calculated, and the differential action result of the entire line is generated. The fiber optic differential protection module spans the intermediate segmentation nodes, directly extracting synchronous sampling data from the first line protection control unit 2 and the fourth line protection control unit 8, treating the entire hybrid line from substation 1 to switching station 9 as a macroscopic single protection body. The derivation of its global dimension calculation logic is as follows: ; ; In the formula, Characterizes the effective value of the differential current along the entire hybrid line; Characterizes the effective value of the braking current along the entire hybrid line; The synchronous sampling current phasor represents the data collected by the first line protection control unit 2 at the head end; The synchronous sampling current phasor is characterized by the fourth line protection control unit 8 at the tail end; The comprehensive capacitance current compensation phasor represents the entire line from a full-line perspective.

[0058] Based on the above global parameters, the criterion equation for generating the differential action results across the entire line is as follows: ; In the formula, The value represents the differential action result of the entire line. A value of one indicates that there is a fault in the macroscopic range of the entire line, and a value of zero indicates that the entire line is normal. Characterizes the threshold of differential starting current across the entire line; Characterizes the braking coefficient of the entire line.

[0059] Since the entire length includes all cable segments, the cumulative effect of its steady-state distributed capacitance and the probability of external interference are greater than those of a single segment. Therefore, the set value of the differential starting current threshold for the entire line must be greater than the differential starting current threshold of any independent section within the system, thereby providing sufficient margin to prevent false tripping from a global perspective.

[0060] S303, after extracting the action identifiers of the entire line and each section, how to determine a unique fault location based on these discrete state variables relies on the logical deduction of multi-source Boolean quantities. Given the characteristics of hybrid collector lines containing different media, subsequent control strategies highly depend on accurate fault location attributes. The internal logic control unit abandons the one-sided judgment method that relies solely on a single extreme value or a single channel, and instead adopts weighted logic with cross-verification of macroscopic and microscopic aspects.

[0061] Combining the differential action results across the entire line and the fault determination results of the section, logical deduction is performed to output the final fault section attribute identifier. When the system detects that the differential action result across the entire line indicates a fault along the entire line, and the synchronously received section fault determination result clearly indicates a fault in overhead line 5 located in the middle position, the global and local feature data corroborate each other. Based on this multi-correlation verification, the system confirms and outputs the fault signal for section 5 of overhead line 5. Conversely, when the system detects that the differential action result across the entire line indicates a fault along the entire line, and the section fault determination result indicates a fault in either cable segment 3 or cable segment 7, the system will confirm and output the fault signal for section 3 of cable segment 3 or the fault signal for section 7 of cable segment 7.

[0062] Considering the risks of communication data link distortion or transformer circuit disconnection in complex engineering environments, which could lead to a disconnect between global and local judgments, this embodiment supplements a matrix singularity anomaly handling mechanism for multi-dimensional data result sets to ensure the integrity of the system's underlying logic judgment. If the system receives a differential action result indicating a fault across the entire line, but within the same synchronization time label window, all independent intervals return a fault-free state, this situation signifies an irreconcilable contradiction between macroscopic and microscopic calculations. The system determines that the underlying data link is mismatched and forcibly downgrades the output to a fault signal for the unknown interval across the entire line. This unknown signal will actively block the adaptive control logic that relies on precise landing point judgment, guiding the device to switch to a conventional safety isolation process, avoiding blind action when the situation is unclear.

[0063] For the phasor extraction process of the Fourier algorithm for AC sampling signals, the design details of the digital filter inside the microprocessor, and the tuning principles of the ratio braking characteristics, those skilled in the art can refer to the microcomputer protection hardware development specifications. The basic theoretical derivation is a well-known technology in this field and will not be elaborated here.

[0064] In this embodiment, refer to the appendix Figure 1 and attached Figure 2 After completing the differential calculation of multi-source data and obtaining accurate fault location attributes through the aforementioned steps, the core engineering task facing the system is how to formulate a reasonable reclosing strategy and anomaly response mechanism based on the characteristics of the fault medium. Based on the above task requirements, this embodiment elaborates on the adaptive reclosing control and anomaly handling steps. The specific implementation process is divided into the following sub-steps: S401 constructs an adaptive reclosing action logic based on fault attributes. In the collector lines of new energy power plants, the fault mechanisms and insulation recovery capabilities differ depending on the transmission medium. The system's internal logic control unit extracts the differential action results for the entire line and the fault determination results for each section. As a preferred method, it outputs the underlying logic control instructions for the reclosing execution module through Boolean logic operations. Its logic control equations are as follows: ; In the formula, This parameter represents the logical action instruction output to the reclosing execution module. A value of 1 indicates that the reclosing sequence is allowed to start, a value of 0 indicates that the reclosing sequence is forcibly blocked, and a value of -1 indicates that the current state is maintained and no action is taken. Characterizes the differential action results across the entire line; Characterizes the fault determination results of section 5 of the overhead line; Characterizes the fault determination result of section 3 of the first cable segment; Characterizes the fault determination result of section 7 of the second cable segment; The logical OR operation represents the condition that either of the two conditions must be met. Assigning a value of one to each of the above state variables indicates that a fault exists in the corresponding area, while assigning a value of zero indicates that the corresponding area is fault-free.

[0065] S402, based on the calculation results of the above control equations, executes a power restoration strategy for section 5 of the overhead line. If the differential action result for the entire line indicates a fault across the entire line, and the fault determination result for section 5 indicates a fault in overhead line section 5, the logic control unit generates an instruction to allow the initiation of the reclosing sequence. To ensure the reliability of the engineering operation and avoid malfunctions caused by a single logic result, the system needs to superimpose multiple verification mechanisms in both the time dimension and the equipment hardware dimension before outputting the actual closing pulse.

[0066] The technical basis for selecting reclosing for overhead line 5 lies in its specific properties. Overhead line 5 is exposed to the natural environment, and its short-circuit faults are mostly caused by transient factors such as lightning flashovers or bird damage. After the circuit breakers at both ends trip and disconnect the short-circuit current, the arc at the fault point loses its energy support, and the air, as the insulating medium, can restore its insulation performance under deionization. Based on this principle, the microprocessor starts the built-in reclosing timer. The reclosing waiting delay parameter is set, typically ranging from 0.5 seconds to 1.5 seconds. This value is determined based on the time limit required for the arc at the fault point to completely extinguish and for the surrounding air to deionize. When the timer reaches the set delay, and the return spring-energized contact signal from the circuit breaker operating mechanism is simultaneously detected as valid, the reclosing execution module inside the first line protection control unit 2 and the fourth line protection control unit 8 officially issues a closing pulse. This multi-dimensional anti-maloperation logic maximizes the grid connection success rate after the transient fault is cleared, thereby mitigating the power generation loss of the renewable energy power plant.

[0067] S403, based on the results of the control equation calculation, executes a forced isolation strategy for the cable section. If the differential action result for the entire line is determined to be a fault across the entire line, and the fault determination result for the section is either the fault in section 3 of the first cable segment or the fault in section 7 of the second cable segment, the logic control unit outputs a forced blocking reclosing sequence instruction, controlling the reclosing execution module to permanently block subsequent operations.

[0068] Unlike the overhead line 5, the faults in the first section of underground cable 3 and the second section of underground cable 7 are mostly caused by the aging and breakdown of the internal cross-linked polyethylene insulation layer or by external mechanical excavation damage. These faults represent irreversible and permanent damage at the material level. If reclosing operations are blindly performed on such damaged insulation, the power grid system will inevitably be subjected to a large-capacity short-circuit current again, generating thermal and electrodynamic impacts, which will then cause secondary damage to the step-up transformer in substation 1 and surrounding intact equipment. Therefore, the device directly cuts off the drive power supply to the closing circuit through an internal control relay, forcibly blocking the reclosing action sequence.

[0069] S404 executes degraded fault-tolerant control under abnormal communication conditions. In a distributed network architecture, fiber optic communication link 10 may be interrupted due to external geological subsidence or construction damage. When any line protection control unit detects the periodic loss of data packets from an adjacent node, and the duration exceeds a preset communication interruption threshold, the system determines that the differential data link in the corresponding interval has failed. To filter out common communication jitter interference, the communication interruption threshold is usually set to the sum of the time of five consecutive normal message exchange cycles in the fiber optic channel. Once a timeout is confirmed, to prevent unpredictable numerical overflow or malfunctions in the differential calculation formula due to missing synchronous sampling values ​​from the other side, the microprocessor actively sends an internal blocking signal to suspend the differential protection logic calculation for the interrupted interval. Considering that power nodes cannot operate without protection after losing primary protection, the system synchronously activates the local backup protection module. This backup protection relies solely on the single-ended current and voltage signals acquired by the signal acquisition module of this node to perform overcurrent determination, thereby providing basic safety isolation protection under extreme conditions of communication loss.

[0070] S405 executes anti-maloperation interlocking control under abnormal hardware conditions. When the low-level self-test program inside the first line protection control unit 2, the second line protection control unit 4, the third line protection control unit 6, or the fourth line protection control unit 8 detects a microprocessor watchdog timeout, a non-volatile memory read / write checksum error, or an out-of-limit deviation of the analog-to-digital converter hardware reference voltage, it directly determines that a hardware-level abnormality has occurred in this unit. At this time, the device disconnects the drive power supply of the trip / close output circuit through the low-level hardware interlocking relay, forcibly cutting off the hardware authority of the abnormal unit to output protection action and reclosing operation. This pure hardware-level interlocking mechanism, which does not rely on software logic judgment, prevents the safety risk of damage to the device's own silicon-based components spreading to the primary high-voltage power system.

[0071] For the logic timing settings of reclosing detection of no voltage and detection of synchronization, the step setting calculation of backup overcurrent protection, and the hardware construction of the watchdog circuit inside the microcomputer protection device, those skilled in the art can refer to the substation secondary system design specifications. The specific implementation details are well-known technologies in this field and will not be elaborated here.

[0072] S406, status verification and subsequent interlocking logic after reclosing operation. See attached... Figure 2When a closing pulse is issued for overhead line 5, the system must evaluate the closing effect to confirm the fault type. After the closing action is completed, the microprocessor synchronously starts the subsequent accelerated protection logic observation time window. If, within a very short time after closing (usually set to 0.1 seconds), the signal acquisition module detects another surge in short-circuit current and the differential action result for the entire line is set to 1 again, then based on the causal relationship, it is determined that the fault of overhead line 5 is not an instantaneous ionized fault, but an irreversible permanent fault such as tree contact or wire breakage. At this time, the reclosing execution module determines that the reclosing has failed, immediately drives the circuit breaker to trip again, generates a permanent fault flag, permanently blocks the reclosing logic for this event, and enters the waiting state for manual fault investigation; conversely, if the electrical parameters remain stable within the subsequent accelerated observation time window, the reclosing is determined to be successful, and the line smoothly resumes normal operation.

[0073] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A new energy station power collection line differential protection and adaptive reclosing device, characterized in that, It includes a line protection control unit, which includes a first line protection control unit (2), a second line protection control unit (4), a third line protection control unit (6), and a fourth line protection control unit (8). A substation (1) is provided on the outside of the first line protection control unit (2), and a switching station (9) is provided on the outside of the fourth line protection control unit (8). A first section of cable (3) is connected between the first line protection control unit (2) and the second line protection control unit (4), an overhead line (5) is connected between the second line protection control unit (4) and the third line protection control unit (6), and a second section of cable (7) is connected between the third line protection control unit (6) and the fourth line protection control unit (8). The first line protection control unit (2), the second line protection control unit (4), the third line protection control unit (6) and the fourth line protection control unit (8) are connected in sequence via an optical fiber communication link (10); The first line protection control unit (2) and the fourth line protection control unit (8) are equipped with reclosing execution modules.

2. The new energy station power collection line differential protection and adaptive reclosing device according to claim 1, characterized in that, The first line protection control unit (2), the second line protection control unit (4), the third line protection control unit (6) and the fourth line protection control unit (8) all include a signal acquisition module, an optical fiber differential protection module and an instruction output module; The signal acquisition module is used to acquire current signals and voltage signals and generate sampled values; The instruction output module is used to output instructions to start reclosing or to block reclosing.

3. The new energy station power collection line differential protection and adaptive reclosing device according to claim 1, characterized in that, The first line protection control unit (2) is provided with a first identification code, the second line protection control unit (4) is provided with a second identification code, the third line protection control unit (6) is provided with a third identification code, and the fourth line protection control unit (8) is provided with a fourth identification code; The first identification code is greater than the second identification code, the second identification code is greater than the third identification code, and the third identification code is greater than the fourth identification code.

4. The differential protection and adaptive reclosing device for the collector lines of new energy power stations according to claim 2, characterized in that, The fiber optic differential protection module is used to acquire the sampled value generated by the signal acquisition module, and is equipped with forward data frames and reverse data frames. The second line protection control unit (4) forwards the forward data frame to the third line protection control unit (6), the forward data frame carrying the sampled value of the second line protection control unit (4), the sampled value of the first line protection control unit (2) and the sampled value of the fourth line protection control unit (8); After receiving the positive data frame, the third line protection control unit (6) replaces the original sampling value of the second line protection control unit (4) in the positive data frame with its own sampling value, and retains the sampling value of the first line protection control unit (2) and the sampling value of the fourth line protection control unit (8) and forwards them to the fourth line protection control unit (8). The third line protection control unit (6) forwards the reverse data frame to the second line protection control unit (4). The reverse data frame carries the sampled value of the third line protection control unit (6), the sampled value of the first line protection control unit (2), and the sampled value of the fourth line protection control unit (8). After receiving the reverse data frame, the second line protection control unit (4) replaces the original sampling value of the third line protection control unit (6) in the reverse data frame with its own sampling value, and forwards the sampling values ​​of the first line protection control unit (2) and the fourth line protection control unit (8) to the first line protection control unit (2).

5. The differential protection and adaptive reclosing device for the collector lines of new energy power stations according to claim 4, characterized in that, The fiber optic differential protection module is used to calculate the differential current in the line section and the differential current throughout the line, and to obtain the differential action result and the fault determination result of the section. When it is determined that the differential action result of the entire line is a fault and the fault determination result of the section is a fault of the overhead line (5) section, the reclosing execution module starts reclosing; When it is determined that the differential action result of the entire line is a fault and the fault determination result of the section is a fault in the first section of cable (3) or a fault in the second section of cable (7), the reclosing execution module blocks the reclosing.

6. A differential protection and adaptive reclosing method for collector lines in new energy power stations, characterized in that, The differential protection and adaptive reclosing device for the collector lines of new energy power stations as described in any one of claims 1-5 includes the following steps: Provides substation (1), first line protection control unit (2), first section of cable (3), second line protection control unit (4), overhead line (5), third line protection control unit (6), second section of cable (7), fourth line protection control unit (8) and switch station (9); Connect the first line protection control unit (2) to the substation (1), and connect the fourth line protection control unit (8) to the switching station (9). Set a first identification code for the first line protection control unit (2), set a second identification code for the second line protection control unit (4), set a third identification code for the third line protection control unit (6), and set a fourth identification code for the fourth line protection control unit (8); The sizes of the first identification code, the second identification code, the third identification code, and the fourth identification code are compared to obtain the size comparison result. The master-slave relationship between two adjacent line protection control units is determined by combining the size comparison result. The line protection control unit is controlled to collect current and voltage signals and generate sampled values; Based on the master-slave relationship, a master-slave bidirectional synchronization method is executed to synchronize the sampled values ​​and obtain synchronized sampled values. The differential current of the line section and the differential current of the entire line are calculated using the synchronous sampled values ​​to obtain the differential action results of the entire line and the fault determination results of the section. Based on the differential action results of the entire line and the fault determination results of the section, the reclosing execution module is controlled to start reclosing or block reclosing.

7. The differential protection and adaptive reclosing method for the collector lines of new energy power stations according to claim 6, characterized in that, Before acquiring the synchronized sample value, a bidirectional data forwarding step-by-step process is included: The second line protection control unit (4) is controlled to forward a positive data frame to the third line protection control unit (6); After receiving the positive data frame, the third line protection control unit (6) replaces the original sampling value of the second line protection control unit (4) in the positive data frame with its own sampling value and forwards it to the fourth line protection control unit (8). The third line protection control unit (6) is controlled to forward a reverse data frame to the second line protection control unit (4); After receiving the reverse data frame, the second line protection control unit (4) replaces the original sample value of the third line protection control unit (6) in the reverse data frame with its own sample value and forwards it to the first line protection control unit (2). During the forwarding process, both the forward data frame and the reverse data frame retain the sampled values ​​of the first line protection control unit (2) and the fourth line protection control unit (8).

8. The differential protection and adaptive reclosing method for the collector lines of new energy power stations according to claim 6, characterized in that, Based on the master-slave relationship, a master-slave bidirectional synchronization method is executed to achieve sampling synchronization and obtain synchronized sample values, including: Based on the master-slave relationship, two adjacent line protection control units are respectively designated as the master and slave ends; The sampling time deviation between the two line protection control units is calculated by controlling the total round-trip delay of the master end and the slave end, as well as the inherent dwell time between receiving and transmitting within the hardware of the line protection control unit. When it is determined that the sampling time deviation is greater than a preset synchronization threshold, the slave end is controlled to adjust the sampling time to achieve synchronization with the master end, so that the sampled value is converted into the synchronized sampled value; When the second line protection control unit (4) or the third line protection control unit (6) is in the sampling adjustment state as the slave end, the synchronous adjustment of the adjacent line protection control unit with an identification code smaller than that of the slave end is blocked; The preset synchronization threshold is the tolerance of the system sampling frequency to the phase angle error between the power grid frequency and the power grid frequency.

9. The differential protection and adaptive reclosing method for the collector lines of new energy power stations according to claim 6, characterized in that, Using the synchronously sampled values, the differential current of the line section and the differential current of the entire line are calculated to obtain the differential operation results of the entire line and the fault determination results of the section, including: The differential current between line sections is calculated using the synchronous sampling values. Combined with the ratio braking principle, a section fault action indicator is generated to determine whether there is an internal fault in this section, or whether there is no fault in this section, or whether it belongs to an external fault. The differential current of the entire line is calculated based on the current of the first line protection control unit (2) and the current of the fourth line protection control unit (8), and the differential action result of the entire line is generated. When it is determined that there is a fault in the macroscopic range of the entire line, the fault of the entire line is output as the differential action result of the entire line. When it is determined that no fault has occurred within the entire macroscopic range, the output "All lines are normal" is taken as the result of the differential action of the entire line. When it is determined that the internal fault occurs in the section where the first section of cable (3) is located or the section where the second section of cable (7) is located, the fault in the section where the first section of cable (3) is located or the fault in the section where the second section of cable (7) is located is output as the fault determination result of the section. When it is determined that the internal fault has not occurred in the section where the first cable segment (3) is located and the section where the second cable segment (7) is located, but the internal fault has occurred in the section where the overhead line (5) is located, the fault of the section of the overhead line (5) is output as the fault determination result of the section. If the differential action result indicates a fault across the entire line, but within the same synchronization time tag window, the fault determination results for all independent intervals return a fault-free state, then the underlying data link is determined to be in a mismatch state, and a forced downgrade output of the fault signal for the unknown interval of the entire line is performed.

10. The differential protection and adaptive reclosing method for the collector lines of new energy power stations according to claim 9, characterized in that, Based on the overall differential action results and the section fault determination results, the reclosing execution module is controlled to initiate reclosing or block reclosing, including: When it is determined that the differential action result of the entire line is a fault of the entire line and the fault determination result of the section is a fault of the overhead line (5) section, the reclosing execution module is controlled to start reclosing; When it is determined that the differential action result of the entire line is a fault of the entire line and the fault determination result of the section is a fault of the first section of cable (3) or a fault of the second section of cable (7), the reclosing execution module is controlled to lock the reclosing; If the results of the differential action of the entire line and the fault determination results of the section do not meet the above conditions for starting reclosing or blocking reclosing, the reclosing execution module is controlled to maintain the current state and not operate. When periodic data packet loss is detected in adjacent nodes and the duration exceeds the preset communication interruption threshold, it is determined that the fiber optic communication link (10) has been interrupted, the differential protection action of the communication interruption interval is blocked, and the local backup protection module is activated. When a hardware-level fault occurs in the line protection control unit, the differential protection operation and reclosing of the line protection control unit with the fault are blocked. The preset communication interruption threshold is the sum of the time for five consecutive normal message exchange cycles in the fiber optic channel.

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