A ring-shaped direct current main line alternating and direct current storage system

Abstract

The application relates to the technical field of power distribution network protection, and discloses a ring-shaped direct-current main line alternating-direct-current storage system, which comprises a distributed detection module, a regional controller, a system protection module, a hybrid direct-current circuit breaker and an energy storage module. The distributed detection module is used for collecting direct-current voltage and current parameters in real time. The regional controller is in communication connection with the distributed detection module, is used for collecting current direction information of adjacent nodes and constructing a direction discrimination matrix. The system protection module is in communication connection with the regional controller, is used for determining a fault section according to the direction discrimination matrix. The hybrid direct-current circuit breaker is arranged in each section line and is connected with the system protection module. The energy storage module is connected with the system protection module and is used for injecting a specific waveform of reverse current into the fault section. Through the cooperative matching of the distributed detection module and the regional controller, the ring-shaped direct-current system fault is quickly and accurately positioned, and the problem of poor selectivity of a traditional protection scheme in a multi-direction power supply scene is effectively solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of power distribution network protection, and particularly relates to a ring-shaped direct-current main line alternating-direct-current storage system. BACKGROUND

[0002] As a new generation of power transmission technology, the direct-current power distribution system has significant advantages in industrial parks, data centers and other scenarios, and the ring-shaped topology structure has become a research hotspot due to its high power supply reliability.

[0003] However, the ring-shaped direct-current system faces special challenges in fault protection: the traditional overcurrent-based protection scheme is difficult to adapt to the multi-directional power supply characteristics of the ring-shaped network, and the complex fault current path makes it difficult to locate; meanwhile, the direct-current fault current has no natural zero point, so that the breaking speed of the circuit breaker is limited, and the existing protection system has the inherent contradiction that the speed and selectivity are difficult to balance. SUMMARY

[0004] The purpose of the application is to provide a ring-shaped direct-current main line alternating-direct-current storage system to solve the above technical problems.

[0005] The purpose of the application can be achieved by the following technical solutions.

[0006] A ring-shaped direct-current main line alternating-direct-current storage system, the system comprising:

[0007] A distributed detection module for real-time acquisition of direct-current voltage and current parameters;

[0008] A regional controller in communication connection with the distributed detection module, for collecting current direction information of adjacent monitoring nodes and constructing a direction discrimination matrix;

[0009] A system protection module in communication connection with the regional controller, for determining a fault section according to the direction discrimination matrix;

[0010] A hybrid direct-current circuit breaker arranged in each section line and connected with the system protection module;

[0011] An energy storage module connected with the system protection module, for injecting a specific waveform of reverse current into the fault section.

[0012] As a further technical solution, the distributed detection module comprises a voltage acquisition unit and a current acquisition unit, the voltage acquisition unit and the current acquisition unit are respectively used for acquiring direct-current voltage parameters and direct-current current parameters; the voltage acquisition unit is electrically connected with a direct-current bus, and the current acquisition unit is coupled with each section line conductor.

[0013] As a further technical solution, the regional controller comprises a data receiving port and a data processing unit, the data receiving port is connected with the distributed detection module, and the data processing unit is used for performing construction operation of the direction discrimination matrix.

[0014] As a further technical solution, the process of constructing the direction discrimination matrix comprises:

[0015] The distributed detection module comprises N monitoring nodes, for any adjacent monitoring nodes i and j:

[0016] Set , ;

[0017] The direction eigenvalue of the node pair (i, j) is calculated through ;

[0018] The matrix is constructed;

[0019] Wherein, , are the time of the fault traveling wave reaching the node i and the node j respectively, is the time difference; is a preset time attenuation constant; i and j are both the number of nodes.

[0020] As a further technical solution, the process of determining the fault section according to the direction discrimination matrix comprises:

[0021] The fault characteristic parameter is calculated through ;

[0022] The fault characteristic parameter is compared with a preset threshold :

[0023] If , the line section between the node i and the node j has a fault risk;

[0024] Otherwise, it is judged that the line section between the node i and the node j has no fault risk.

[0025] As a further technical solution, the process of determining the fault section according to the direction discrimination matrix further comprises: when the fault characteristic parameter is less than the preset threshold , a confidence index is calculated through the following formula:

[0026] ; wherein, is the number of adjacent monitoring nodes participating in the calculation;

[0027] a confidence index is calculated and a preset confidence threshold is compared:

[0028] If , the line section between node i and node j is determined as a fault section;

[0029] If , the line section between node i and node j is not determined as a fault section.

[0030] As a further technical solution, the hybrid DC circuit breaker comprises a main current-carrying branch and an auxiliary breaking branch;

[0031] The main current-carrying branch is connected in series in the DC line for carrying continuous operating current when the system is in normal operation; the auxiliary breaking branch comprises a solid-state switch unit and an energy absorption unit, and is connected in parallel at both ends of the main current-carrying branch;

[0032] The solid-state switch unit is used for current transfer and breaking at the time of fault; the energy absorption unit is used for absorbing overvoltage energy generated in the breaking process;

[0033] When a fault section is monitored, the corresponding auxiliary breaking branch quickly cuts off the current of the fault section, and then the main current-carrying branch is safely opened under zero-current condition.

[0034] As a further technical solution, the energy storage module comprises an energy storage medium and a power conversion device, and the energy storage medium is connected with the DC bus through the power conversion device; the power conversion device is used for controlling energy conversion and power regulation between the energy storage medium and the DC bus.

[0035] The present application has the following advantages: through the cooperative matching of the distributed detection module and the regional controller, the present application realizes the rapid and accurate positioning of the fault of the ring-shaped DC system, effectively solves the problem of insufficient selectivity of the traditional protection scheme in the multi-direction power supply scene. The hybrid DC circuit breaker combined with the reverse current injection of the energy storage module significantly improves the cutting speed and arc extinguishing effect of the fault current, and overcomes the technical problem of no natural zero point of the DC system; the multi-level decision mechanism of the system protection module ensures the reliability and coordination of the protection action under complex working conditions, and provides a complete fault protection solution for the AC / DC energy storage integrated system. BRIEF DESCRIPTION OF DRAWINGS

[0036] The present application will be further described below in conjunction with the drawings.

[0037] Figure 1 The figure is a system framework diagram of the ring-shaped DC main line AC / DC energy storage system in the present application. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work are within the protection scope of the present application.

[0039] Please refer to Figure 1 An annular direct-current main line alternating-current and direct-current storage system is shown in the figure, and the system comprises:

[0040] A distributed detection module is configured to collect direct-current voltage and current parameters in real time.

[0041] A regional controller is in communication connection with the distributed detection module, configured to collect current direction information of adjacent monitoring nodes and construct a direction discrimination matrix. A system protection module is in communication connection with the regional controller, configured to determine a fault section according to the direction discrimination matrix. The holographic perception is realized through the distributed detection network, and the direction discrimination algorithm based on space-time correlation breaks through the positioning difficulty of the annular topology.

[0042] A hybrid direct-current circuit breaker is arranged in each section line and connected with the system protection module. The collaborative control of the hybrid circuit breaker and the intelligent energy storage solves the technical bottleneck of direct-current breaking.

[0043] An energy storage module is connected with the system protection module and configured to inject a specific waveform of reverse current into the fault section.

[0044] The collaborative working mechanism of the system, for example, when a fault occurs, the distributed detection module captures abnormal signals within 100 μs, the regional controller completes preliminary positioning within 300 μs, the system protection module makes a decision within 500 μs by comprehensively considering multi-source information, the hybrid circuit breaker completes breaking within 1 ms, and at the same time, the energy storage system injects an optimized reverse current (amplitude ≥ 30% of the fault current) to accelerate arc extinction. After the fault is cleared, the system automatically restores power supply within 15 ms.

[0045] Through the above technical solutions, the embodiment realizes rapid and accurate positioning of the annular direct-current system fault through the collaborative cooperation of the distributed detection module and the regional controller, effectively solves the problem of insufficient selectivity of the traditional protection scheme in the multi-direction power supply scene. The reverse current injection of the hybrid direct-current circuit breaker combined with the energy storage module significantly improves the breaking speed and arc extinction effect of the fault current, and overcomes the technical problem that the direct-current system has no natural zero point. The multi-level decision mechanism of the system protection module ensures the reliability and coordination of the protection action under complex working conditions, and provides a complete fault protection solution for the alternating-current and direct-current storage integrated system.

[0046] The distributed detection module comprises a voltage acquisition unit and a current acquisition unit, and the voltage acquisition unit and the current acquisition unit are respectively used for acquiring direct-current voltage parameters and direct-current current parameters; the voltage acquisition unit is electrically connected with a direct-current bus, and the current acquisition unit is coupled with each section line conductor. Through the above technical solution, the distributed detection module in the embodiment realizes accurate measurement and high-speed transmission of electrical parameters of a direct-current system through the optimized design and collaborative work of the voltage and current acquisition units.

[0047] The area controller comprises a data receiving port and a data processing unit, the data receiving port is connected with the distributed detection module, and the data processing unit is used for performing construction operation of a direction discrimination matrix. The data receiving port adopts a multi-channel parallel interface design, establishes a low-delay communication connection with the distributed detection module, supports real-time reception of current direction signals and accurate time stamp information of each monitoring node; the data processing unit integrates a special matrix operation coprocessor and a fault feature recognition algorithm, dynamically constructs a direction discrimination matrix reflecting the fault current distribution of the whole network by analyzing the current direction correlation and traveling wave propagation timing characteristics of adjacent monitoring nodes, intelligently analyzes the matrix eigenvalues by using an adaptive threshold mechanism, and finally outputs a confidence evaluation result of a suspected fault section. Through the collaborative optimization of hardware acceleration and software algorithm, the area controller realizes rapid extraction and preliminary positioning of fault features, provides high-reliability intermediate layer data processing support for decision-making of a system protection module, and effectively improves the accuracy and real-time performance of fault diagnosis of a ring-shaped direct-current system.

[0048] The process of constructing the direction discrimination matrix comprises:

[0049] The distributed detection module comprises N monitoring nodes, and for any adjacent monitoring nodes i and j:

[0050] It is set that , ;

[0051] The direction eigenvalue of the node pair (i, j) is calculated by

[0052] The matrix is constructed.

[0053] Wherein, , are the times of the fault traveling wave reaching the node i and the node j respectively, is the time difference; is a preset time attenuation constant; i and j are both the numbers of nodes.

[0054] ​Through the above technical solution, this embodiment provides a process for constructing a direction discrimination matrix. Specifically, firstly, the number of monitoring nodes included in the distributed detection module is counted and denoted as N. Then, for any adjacent monitoring nodes i and j:

[0055] set up ,pass Calculate the time difference between the arrival of the fault traveling wave at node i and node j, by... Calculate the directional eigenvalues ​​of the obtained node pairs, denoted as (i,j). Finally, construct a matrix based on the eigenvalues. .

[0056] The process of determining the fault section based on the direction discrimination matrix includes:

[0057] pass Calculate and obtain fault characteristic parameters ;

[0058] Fault characteristic parameters With preset threshold Compare:

[0059] like The line segment between node i and node j is at risk of failure.

[0060] Otherwise, determine that there is no risk of fault in the line segment between node i and node j.

[0061] Through the above technical solution, this embodiment provides a process for initially identifying line sections that may be prone to faults. Specifically, through... Calculate and obtain fault characteristic parameters , among which, according to From the definition, we can know for The opposite of the normal value, when a fault occurs in a certain section, the traveling wave generated at the fault point will propagate along the line to both sides at near the speed of light (approximately 300 m / μs). Because the fault point is located within this section, the traveling wave only needs to traverse a portion of the section length to reach the two end nodes, rather than the entire ring network, forming the shortest propagation path, resulting in a very small time difference. Normal section Smaller, due to the time difference of traveling wave propagation The amplitude is relatively large, and the exponential decay is significant. However, in the fault section, the traveling wave propagation time difference near the fault point is relatively large. Very small, in case of failure and The opposite signs and similar amplitudes highlight the contradictory current directions at the fault location. Based on the above, the fault characteristic parameters are... With preset threshold Compare: If If the line section between node i and node j is at risk of failure; otherwise, it is determined that the line section between node i and node j is not at risk of failure.

[0062] The process of determining the fault section according to the direction discrimination matrix further includes: when the fault characteristic parameter is less than a preset threshold , a confidence index is calculated by the following formula :

[0063] ; wherein, is the number of adjacent monitoring nodes participating in the calculation;

[0064] The confidence index is compared with a preset confidence threshold :

[0065] If , it is determined that the line section between node i and node j is a fault section.

[0066] If , it is determined that the line section between node i and node j is not a fault section.

[0067] In an actual system, there are interference factors such as measurement noise and traveling wave distortion. Only the single index of the direction discrimination matrix may lead to misjudgment. The confidence index can effectively filter out incidental interference through multi-node data cross-validation. The closed-loop characteristics of the ring network may cause temporary current direction conflicts in non-fault sections (for example, when adjacent sections are simultaneously faulty). The confidence calculation avoids being misled by local features by evaluating the consistency of all nodes in the network. The embodiment provides a calculation process of the confidence index, specifically, a calculation confidence index is obtained by the formula , and then the confidence index is compared with a preset confidence threshold : if , it is determined that the line section between node i and node j is a fault section; if , it is determined that the line section between node i and node j is not a fault section.

[0068] The hybrid DC circuit breaker includes a main current-carrying branch and an auxiliary breaking branch.

[0069] The main current-carrying branch is connected in series in the DC line and is used to carry the continuous working current when the system is normally running; the auxiliary breaking branch includes a solid-state switch unit and an energy absorption unit and is connected in parallel at both ends of the main current-carrying branch.

[0070] The solid-state switch unit is used for current transfer and breaking in case of failure; and the energy absorption unit is used for absorbing overvoltage energy generated in the breaking process.

[0071] When a fault section is monitored, a corresponding auxiliary breaking branch quickly cuts off the current of the fault section, and then the main through-flow branch safely cuts off under the condition of zero current.

[0072] Through the above technical solution, the hybrid DC circuit breaker in the embodiment realizes efficient breaking and energy dissipation of the DC system fault current through the cooperation of the main through-flow branch and the auxiliary breaking branch. The main through-flow branch undertakes the normal through-flow task and ensures low-loss operation; the solid-state switch unit in the auxiliary breaking branch realizes microsecond-level fast breaking, and the energy absorption unit effectively suppresses the operating overvoltage. When a fault occurs, the auxiliary branch first completes current transfer and cutting off, and then the main through-flow branch is safely opened under the condition of zero current. The design has the following obvious advantages: first, the arc energy is concentrated in the auxiliary branch for processing, protecting the main through-flow contact; second, the two-stage breaking strategy takes into account the breaking speed and equipment safety; third, the multi-stage design of the energy absorption unit can adapt to different levels of fault energy; in addition, the main and auxiliary branches have clear division of labor, prolonging the overall life of the equipment. The hybrid structure effectively solves the contradiction between speed, reliability and economy of the DC circuit breaker, and provides a reliable fault isolation means for the ring-shaped DC system.

[0073] The energy storage module comprises an energy storage medium and a power conversion device, the energy storage medium is connected with the DC bus through the power conversion device; and the power conversion device is used for controlling energy conversion and power regulation between the energy storage medium and the DC bus.

[0074] Through the above technical solution, the energy storage module in the embodiment realizes efficient storage and flexible scheduling of system energy through the cooperation of the energy storage medium and the power conversion device. The energy storage medium adopts a composite energy storage structure, which has both energy storage and power support capabilities; and the power conversion device, as the core hub of energy interaction, can realize functions such as voltage level conversion, bidirectional power flow control, multi-mode intelligent switching and dynamic harmonic suppression. Through intelligent regulation and control of the power conversion device, the energy storage module can not only provide millisecond-level fault current support, but also participate in steady-state energy management of the system, significantly improving the power supply reliability and operation economy of the ring-shaped DC system, and its modular architecture facilitates capacity expansion and maintenance.

[0075] The present application can be a system, a method, and / or a computer program product. The computer program product can include a computer readable storage medium having computer readable program instructions embodied therewith to implement various aspects of the present application.

[0076] Computer readable storage media can be tangible storage devices that can retain and store instructions for use by an instruction execution device. Computer readable storage media can be, for example, but is not limited to, electronic storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer readable storage media include the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire.

[0077] Computer readable program instructions described herein can be downloaded to respective computing / processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and / or a wireless network. The network can comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and / or edge servers. A network adapter card or network interface in each computing / processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing / processing device.

[0078] While this application has been disclosed with reference to the above embodiments, it will be understood by those skilled in the art that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the application. In addition, many modifications can be made to adapt to a particular situation and the teachings of the present disclosure to a specific application without departing from the scope of the application. Therefore, it is intended that the application not be limited to the embodiments disclosed herein but will include all changes without departing from the true spirit and technical scope of the application.

Claims

1. A ring-shaped DC main line AC-DC storage system characterized by comprising: The system comprises: a distributed detection module for collecting direct current voltage and current parameters in real time; a regional controller in communication connection with the distributed detection module, for collecting current direction information of adjacent nodes and constructing a direction discrimination matrix; a system protection module in communication connection with the regional controller, for determining a fault section according to the direction discrimination matrix; a hybrid direct current circuit breaker arranged in each section line and connected with the system protection module; an energy storage module connected with the system protection module, for injecting a specific waveform of reverse current into the fault section; the process of constructing the direction discrimination matrix comprises: the distributed detection module comprises N monitoring nodes, for any adjacent monitoring nodes i and j: Set , ; By computing the direction eigenvalue of the obtained node pair (i, j); Constructing a matrix ; wherein, , are the time of fault traveling wave arriving at node i and node j respectively, is the time difference; is a preset time decay constant; i and j are both the number of nodes; the process of determining the fault section according to the direction discrimination matrix comprises: By Computing the fault feature parameter ; The fault characteristic parameters are compared with preset threshold values. are compared with preset threshold values.​ If then the line section between node i and node j is at risk of failure; otherwise, it is determined that the line section between the node i and the node j is free of fault risk.

2. A ring-shaped DC main line AC-DC storage system according to claim 1, characterized by The distributed detection module comprises a voltage acquisition unit and a current acquisition unit, the voltage acquisition unit and the current acquisition unit are respectively used for collecting direct current voltage parameters and direct current current parameters; the voltage acquisition unit is electrically connected with a direct current bus, and the current acquisition unit is coupled with each section line conductor.

3. A ring-shaped DC main line AC-DC storage system according to claim 2, characterized by The regional controller comprises a data receiving port and a data processing unit, the data receiving port is connected with the distributed detection module, and the data processing unit is used for executing the construction operation of the direction discrimination matrix.

4. A ring-shaped DC main line AC-DC storage system according to claim 3, characterized by The process of determining the fault section according to the direction discrimination matrix further comprises: when the fault characteristic parameter is less than a preset threshold , a confidence index is calculated by the following formula : ; wherein, is the number of adjacent monitoring nodes participating in the calculation; The confidence indicator with a preset confidence threshold The comparison is made: If then the line section between node i and node j is determined to be a fault section; If then the line section between node i and node j is not a fault section.

5. A ring-shaped DC main line AC-DC storage system according to claim 4, characterized by The hybrid direct current circuit breaker comprises a main current-carrying branch and an auxiliary breaking branch; The main current-carrying branch is connected in series in the direct current line, and is used for carrying continuous working current when the system is in normal operation; the auxiliary breaking branch comprises a solid-state switch unit and an energy absorption unit, and is connected in parallel at both ends of the main current-carrying branch; The solid-state switch unit is used for current transfer and breaking in the event of a fault; the energy absorption unit is used for absorbing overvoltage energy generated in the breaking process; When the fault section is monitored, the corresponding auxiliary breaking branch quickly cuts off the current of the fault section, and then the main current-carrying branch is safely opened under the condition of zero current.

6. A ring-shaped DC main line AC-DC storage system according to claim 5, characterized by The energy storage module comprises an energy storage medium and a power conversion device, the energy storage medium is connected with the direct current bus through the power conversion device; the power conversion device is used for controlling energy conversion and power regulation between the energy storage medium and the direct current bus.

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