A method, device and medium for rapid protection of active distribution network

Abstract

The present invention discloses a method, device, and medium for rapid protection of an active distribution network. The method includes: real-time acquisition of electrical quantities at each node of the distribution network; determining whether communication between protection devices on both sides is normal based on the acquired electrical quantities at each node; if communication between the protection devices on both sides is normal, transmitting the electrical quantities at each node to a central control decision unit of the protection device, and calculating a current amplitude difference based on the electrical quantities at each node; determining whether an internal or external fault exists based on the current amplitude difference and a preset amplitude differential protection criterion, and activating a protection output of the protection device in the event of an internal fault; calculating a negative-sequence current secondary mutation value based on the electrical quantities at each node in the event of an abnormal or interrupted communication between the protection devices on both sides; determining an internal fault if the overcurrent stage II protection on the local side continuously operates and does not return, and activating an accelerated protection output based on the negative-sequence current secondary mutation value and a preset overcurrent stage II accelerated protection criterion.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network protection, and more particularly to a method, device and medium for rapid protection of an active distribution network. Background Art

[0002] The high penetration of distributed power sources, such as wind and photovoltaic power, and the increasing use of ring networks are driving the shift of traditional distribution networks from radial to multi-terminal active networks. This makes common three-stage current protection and fault location methods based on overcurrent principles difficult to apply. Current differential protection, a well-established method in transmission networks, requires strict synchronization of electrical quantity data at both ends. Whether relying on fiber-optic communications or wireless communications like 5G, synchronization performance can degrade. Traditional phasor differential protection will block, typically requiring only three-stage overcurrent protection for fault isolation. However, current amplitudes on both sides of the line are still accurately measured, resulting in slow protection operation. Summary of the Invention

[0003] In view of the deficiencies in the prior art, the present invention provides a method, device and medium for rapid protection of an active distribution network.

[0004] According to one aspect of the present invention, a method for rapid protection of an active power distribution network is provided, comprising:

[0005] Real-time collection of electrical quantities at each node in the distribution network, including the electrical quantities of each node itself and the electrical quantities received from the opposite node;

[0006] Based on the collected electrical quantities of each node, determine whether the communication between the protection devices on both sides is normal;

[0007] When the communication between the protection devices on both sides is normal, the electrical quantity of each node is transmitted to the central control decision unit of the protection device, and the central control decision unit calculates the current amplitude difference based on the electrical quantity of each node;

[0008] According to the current amplitude difference and the preset amplitude differential protection criterion, the internal and external faults are judged, and in the case of internal faults, the protection device protection action output;

[0009] In the event of an abnormality or interruption in the communication between the protection devices on both sides, the central control decision unit calculates the secondary mutation amount of the negative sequence current based on the electrical quantities of each node;

[0010] When the overcurrent II protection on this side operates continuously and does not return, it is judged as an internal fault. The protection accelerated action outlet is protected according to the secondary mutation amount of the negative sequence current and the preset overcurrent II accelerated protection criterion.

[0011] Optionally, the amplitude differential protection criterion is:

[0012]

[0013] Where, They are the current phasors detected by the protection on both sides of the line M and N, M is the sending side, N is the receiving side, I set The braking amount is the action threshold set to avoid unbalanced current.

[0014] Optionally, priority is given to ensuring that when a fault occurs outside the zone, the braking amount I set Set to:

[0015]

[0016] Where, They are the current phasors detected by the protection on both sides of line N, N is the receiving end side, K res is the reliability coefficient, ranging from 1.1 to 1.2.

[0017] Optionally, when a distribution network line fails outside the MN area, the current vectors on the sending side M and the receiving side N of the line are satisfy:

[0018]

[0019] Where, They are the current phasors detected by the protection on both sides of the line M and N, M is the sending side and N is the receiving side.

[0020] Optionally, when a fault occurs in the MN area of ​​a distribution network line, the current vectors on the sending side M and the receiving side N of the line are satisfy:

[0021]

[0022] Where, They are the current phasors detected by the protection on both sides of the line M and N, M is the sending side and N is the receiving side.

[0023] Optionally, the protection accelerated action exit conditions are: the overcurrent II stage protection continuously operates and does not return, the negative sequence current amplitude undergoes two sudden changes and the action time needs to avoid instantaneous faults.

[0024] According to another aspect of the present invention, there is provided an active power distribution network fast protection device, comprising:

[0025] The acquisition module is used to collect the electrical quantities of each node in the distribution network in real time, where the electrical quantities include the electrical quantities of each node itself and the electrical quantities received from the opposite nodes;

[0026] The judgment module is used to judge whether the communication between the protection devices on both sides is normal based on the collected electrical quantities of each node;

[0027] A first calculation module is configured to transmit the electrical quantity of each node to a central control decision unit of the protection device when communication between the protection devices on both sides is normal, and the central control decision unit calculates the current amplitude difference based on the electrical quantity of each node;

[0028] The protection action output module is used to judge the internal and external faults according to the current amplitude difference and the preset amplitude differential protection criterion, and to activate the protection action output of the protection device in the event of an internal fault;

[0029] The second calculation module is used to calculate the negative sequence current secondary mutation amount based on the electrical quantity of each node by the central control decision unit when the communication between the protection devices on both sides is abnormal or interrupted;

[0030] The protection acceleration action output module is used to judge it as an internal fault when the overcurrent II protection on this side continuously operates and does not return. It protects the accelerated action output according to the secondary mutation amount of the negative sequence current and the preset overcurrent II accelerated protection criterion.

[0031] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the storage medium stores a computer program, and the computer program is used to execute the method according to any one of the above aspects of the present invention.

[0032] According to another aspect of the present invention, an electronic device is provided, comprising: a processor; a memory for storing instructions executable by the processor; and the processor for reading the executable instructions from the memory and executing the instructions to implement the method described in any one of the above aspects of the present invention.

[0033] Therefore, this invention proposes a current amplitude differential protection criterion for active distribution networks. This criterion can be used directly as primary protection or as a backup for traditional phasor differential protection. When data synchronization is disrupted or degraded across the communication system, causing traditional phasor differential protection to be disabled, the protection can be maximized by utilizing only the amplitude information of the current data on both sides. A novel fast integrated protection scheme for active distribution networks is also proposed. This scheme can adapt to various communication and data transmission scenarios. When a communication system transmission interruption occurs, sequential fast-acting protection can be used to accelerate the traditional overcurrent protection stage II, ensuring rapid circuit breaker operation in the event of a severe line fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0035] Figure 1 1 is a flow chart of a method for rapid protection of an active distribution network provided by an exemplary embodiment of the present invention;

[0036] Figure 2 is another flow chart of a method for rapid protection of an active distribution network provided by an exemplary embodiment of the present invention;

[0037] Figure 3 is a schematic diagram of an active power distribution network provided by an exemplary embodiment of the present invention;

[0038] Figure 4 is a schematic diagram of an out-of-area fault equivalent network provided by an exemplary embodiment of the present invention;

[0039] Figure 5 is a schematic diagram of an equivalent network for intra-area faults provided by an exemplary embodiment of the present invention;

[0040] Figure 6 is a logic diagram of sequential quick-acting protection provided by an exemplary embodiment of the present invention;

[0041] Figure 7 This is a PSCAD simulation model diagram of a 10kV active power distribution network provided by an exemplary embodiment of the present invention;

[0042] Figure 8 1 is a schematic structural diagram of an active power distribution network fast protection device provided by an exemplary embodiment of the present invention;

[0043] Figure 9 This is a structure of an electronic device provided by an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0044] Below, the exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0045] It should be noted that the relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0046] Those skilled in the art will understand that the terms "first" and "second" in the embodiments of the present invention are only used to distinguish different steps, devices or modules, and neither represent any specific technical meaning nor indicate the necessary logical order between them.

[0047] It should also be understood that, in the embodiments of the present invention, “a plurality of” may refer to two or more than two, and “at least one” may refer to one, two or more than two.

[0048] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more, unless explicitly limited or otherwise indicated in the context.

[0049] In addition, the term "and / or" in this invention merely describes an association relationship between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Furthermore, the character " / " in this invention generally indicates that the related objects are in an "or" relationship.

[0050] It should also be understood that the description of the various embodiments of the present invention focuses on the differences between the various embodiments, and the same or similar aspects thereof can be referenced with each other. For the sake of brevity, they will not be described one by one.

[0051] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0052] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0053] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0054] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0055] Embodiments of the present invention can be applied to electronic devices such as terminal devices, computer systems, and servers, and can operate in conjunction with numerous other general-purpose or specialized computing system environments or configurations. Examples of well-known terminal devices, computing systems, environments, and / or configurations suitable for use with terminal devices, computer systems, servers, and other electronic devices include, but are not limited to, personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network personal computers, minicomputer systems, mainframe computer systems, and distributed cloud computing technology environments including any of the above.

[0056] Electronic devices such as terminal devices, computer systems, and servers can be described in the general context of computer system-executable instructions (such as program modules) executed by a computer system. Generally, program modules can include routines, programs, object programs, components, logic, data structures, etc., which perform specific tasks or implement specific abstract data types. Computer systems / servers can be implemented in a distributed cloud computing environment, where tasks are performed by remote processing devices linked via a communication network. In a distributed cloud computing environment, program modules can be located on local or remote computing system storage media, including storage devices.

[0057] Exemplary Methods

[0058] Figure 1 This is a flow chart of a method for rapid protection of an active distribution network provided by an exemplary embodiment of the present invention. This embodiment can be applied to electronic devices, such as Figure 1 As shown, the active distribution network fast protection method 100 includes the following steps:

[0059] Step 101: collect the electrical quantity of each node in the distribution network in real time, where the electrical quantity includes the electrical quantity of each node itself and the electrical quantity received from the opposite node;

[0060] Step 102: judging whether the communication between the protection devices on both sides is normal based on the collected electrical quantities of each node;

[0061] Step 103: If communication between the protection devices on both sides is normal, the electrical quantity of each node is transmitted to the central control decision unit of the protection device, and the central control decision unit calculates the current amplitude difference based on the electrical quantity of each node;

[0062] Step 104, judging whether the fault is inside or outside the zone according to the current amplitude difference and the preset amplitude differential protection criterion, and in the case of an inside fault, the protection device operates at the output;

[0063] Step 105: When the communication between the protection devices on both sides is abnormal or interrupted, the central control decision unit calculates the negative sequence current secondary mutation amount based on the electrical quantity of each node;

[0064] Step 106: When the overcurrent II protection on this side continuously operates and does not return, it is determined to be an internal fault, and the protection is accelerated according to the negative sequence current secondary mutation amount and the preset overcurrent II accelerated protection criterion.

[0065] Specifically, refer to Figure 2 As shown in FIG, a new fast integrated protection scheme for active distribution network includes the following steps: Figure 3 This is a schematic diagram of the active distribution network topology:

[0066] (1) Using data acquisition devices to collect electrical quantities at each node of the distribution network in real time;

[0067] (2) Determine whether the communication between the protection devices on both sides is normal. If normal, proceed to step (3); if the communication is abnormal or interrupted, proceed to step (5);

[0068] (3) Transmitting the current amplitude of each node to the central control decision unit;

[0069] (4) When communication is normal, after receiving the current amplitude information from the opposite side, the central control decision unit calculates the absolute value of the current amplitude difference and determines whether it is an internal or external fault according to the amplitude differential protection criterion. If it is an internal fault, the protection action output is activated;

[0070] (5) Transmitting the negative sequence current amplitude of each node to the central control decision unit;

[0071] (6) When communication is abnormal or interrupted, the central control decision unit calculates the secondary mutation of the negative sequence current, and the overcurrent II stage accelerated protection judgment criteria are used to determine whether the fault is inside or outside the zone. If it is an inside zone fault, the protection accelerated action output.

[0072] in:

[0073] Furthermore, the amplitude differential protection criterion in step (4) is as follows:

[0074]

[0075] Where, I is the fault current phasor detected by the protection on both sides of the line M and N, M is the sending side, and N is the receiving side. set The braking amount is the action threshold set to avoid unbalanced current.

[0076] Prioritize safety in the event of out-of-zone faults. set The settings are as follows:

[0077]

[0078] Where K res It is the reliability coefficient, which is generally between 1.1 and 1.2.

[0079] When a distribution network line fails outside the MN area, Figure 4 , the current amplitude on both sides of line M and N satisfy:

[0080]

[0081] When a fault occurs in the MN area of ​​a distribution network line, such as Figure 5 , the current amplitude on both sides of line M and N satisfy:

[0082]

[0083] Furthermore, the overcurrent II stage accelerated protection exit conditions in step (6) are: 1) the overcurrent II stage protection on this side continuously operates and does not return; 2) two sudden changes in the negative sequence current amplitude are detected; 3) the action time must avoid instantaneous faults. Figure 6 .

[0084] In addition, with Figure 3 For example, the line MN is connected to a DG downstream and has branch loads. For the MN section of the corresponding line, if the control characteristics of the distributed power supply are ignored, the potentials on both sides are considered to be equal in amplitude. The equivalent network for the out-of-area fault is as follows: Figure 4 shown.

[0085] The corresponding power supply potentials at the beginning and end of the line are the system side power supply electromotive force and the distributed power supply side electromotive force, respectively. M , Z N are the equivalent impedances of the system side and the distributed power supply side, Z L is the total impedance of line MN, and f1 is the fault point. At this time, the fault current phasors detected by the protection on both sides of line M and N are:

[0086]

[0087]

[0088] It can be seen that when the fault f1 occurs outside the zone, the current amplitudes on both sides of the line M and N are satisfy:

[0089] When point f2 in the area fails, the equivalent network of the fault in the area is as follows Figure 5 As shown in the figure, Z1 and Z2 are the line impedances on both sides of the fault point. The conversion relationship between the impedances is as follows:

[0090]

[0091] Where m is the ratio of the equivalent impedance of the system M to the line impedance, and n is the ratio of the equivalent impedance of the distributed generation N to the line impedance. The coefficient β is the ratio of the distance from the fault point f2 to the bus M side to the total length of the line MN.

[0092] At this time, the fault current phasors detected by the protection on both sides of line M and N are:

[0093]

[0094]

[0095] It can be seen that when the fault f2 occurs in the area, it can be obtained from formula (8) (9)

[0096] (2) Overcurrent II stage accelerated protection judgment criteria

[0097] When an asymmetric fault occurs, sequential quick-acting protection operates based on the principle of a secondary sudden change in negative-sequence current. When the distribution network transitions from normal operation to a faulty state, the negative-sequence amplitude component experiences a first sudden change. If the opposite-end circuit breaker can trip the faulted phase using stage I protection, this will inevitably cause a second sudden change in the negative-sequence amplitude component. By detecting these two sudden changes in the negative-sequence component, the current protection device at the local end can construct a sequential quick-acting protection criterion based on the second sudden change in the negative-sequence current.

[0098] The sequential quick-acting protection is coordinated with the existing three-stage overcurrent protection in the distribution network to ensure selectivity. After a fault occurs, only when the overcurrent stage II protection on this side continuously operates and does not return, it is considered an internal fault, and the circuit breaker on this side is tripped quickly; otherwise, it is considered an external fault and the circuit breaker on this side does not operate. This is the triggering criterion within the protection zone:

[0099]

[0100] In the formula is the setting value of overcurrent stage II, I a is the overcurrent amplitude.

[0101] Combined with the sudden change criterion and interval criterion of the sequential quick-acting protection under asymmetric fault, the action logic diagram of the sequential quick-acting protection is as follows: Figure 7 shown.

[0102] The use of sequential quick-acting protection to accelerate the second stage of the traditional three-stage current protection is expected to greatly shorten the action time. The overall time is:

[0103] t=t st +Δt2(11)

[0104] Where, t st = Δt2 represents the activation time of the Stage II protection, which should not exceed the operating time of the opposite Stage 1 protection and should be less than 20ms. Δt2 represents the short delay given to avoid transient faults, with a value of 100ms. The overall solution ensures that the faulty line is cleared within 120ms, far less than the time required to wait for the traditional Stage II protection to operate.

[0105] (3) Simulation results

[0106] Based on PSCAD / EMTDC simulation software, build Figure 6The 10kV cable distribution network model with DG is shown in Figure 1. The neutral point is grounded via a small resistor with a grounding resistance of 10Ω. The lengths of lines AM, MN, and NO are 2, 8, and 4km respectively. The loads Ld1, Ld2, and Ld3 are 1.5MV·A, and the power factor is 0.85. The DG is an inverter type with a rated capacity of 1.5MV·A. The unit positive sequence impedance of the lines is 0.088+j0.069Ω / km. res The value is 1.1.

[0107] a. Out-of-area fault

[0108] Taking line MN as an example, different types of metallic short-circuit faults were set at f4, the downstream exit outside the zone, and f5, 4 km from the exit, to examine the operational safety of the criterion under the out-of-zone fault scenario. The operation of the proposed amplitude differential protection scheme is as follows:

[0109] Table 1 Protection scheme action when fault occurs outside the zone

[0110]

[0111]

[0112] Action status: × indicates that the protection is not in action, √ indicates that the protection is in action, the same below.

[0113] For out-of-zone faults, the proposed new amplitude differential protection scheme can correctly not operate under different fault locations and fault types, demonstrating its operational safety in out-of-zone fault scenarios.

[0114] b. Faults within the area

[0115] Taking line MN as an example, short-circuit faults of different types and transition resistances were set at point f1 near busbar M, at the line midpoint f2, and at point f3 near busbar N within its zone. The sensitivity of the criterion to these faults was examined. The proposed amplitude differential protection scheme operated as follows with a 50Ω transition resistance:

[0116] Table 2 Protection scheme action when 50Ω transition resistance fault occurs in zone

[0117]

[0118] For intra-zone faults, the proposed amplitude differential protection scheme operates correctly under various fault types and transition resistances. Simulations show that the proposed scheme can still operate quickly and accurately with higher transition resistances. The operating boundary resistances for three-phase, two-phase-to-ground, and single-phase-to-ground faults are all greater than 300Ω, and for two-phase faults, the operating boundary resistance is greater than 450Ω.

[0119] c. Adaptability verification considering different DG types and permeability

[0120] Considering different DG types and the adaptability of their criteria at varying penetration rates, the simulation primarily verified whether the output of the DG at the weak sending end and the post-fault control strategy would affect its correct operation. In fact, in the previous two simulations, with a total load of 4.5 MV·A and an inverter power output (photovoltaic) of 1.5 MV·A, the DG penetration rate had already reached over 30%. In light of this reality, the following fault simulations added DG as a wind turbine type. For both photovoltaic (PV) and doubly-fed wind turbine (DFIG) DG types, the accuracy and time of the amplitude differential protection were recorded, considering different penetration rates (reflected by DG output), as shown in the table below.

[0121] Table 3 Protection action of photovoltaic DG at different penetration rates

[0122]

[0123] Table 4 Protection scheme operation of wind turbine DG at different penetration rates

[0124]

[0125] It can be seen that the proposed amplitude differential protection scheme operates within 10ms for different DG types and penetration rates, validating the rationale of the model. This means that the amplitude differential protection correctly identifies faults within and outside the zone before the DG's control strategy changes due to a sudden voltage drop at the generator terminal. During the post-fault period considered in the amplitude differential protection theoretical analysis, the DG can be treated as a normal system power source, with only its weak infeed characteristics considered.

[0126] d. Performance verification of the proposed protection scheme under communication interruption scenario

[0127] Taking the M-terminal of line MN as an example, metallic asymmetric faults were set near the N-terminal within the area (1 km from the N-terminal) and at the near end (0.5 km from the N-terminal) and far end (3.5 km from the N-terminal) of the downstream line outside the area to examine the performance of the successive protection. The performance characteristics for both internal and external faults are shown below. The initiation and operation of the successive protection at M are shown below.

[0128] Table 5 Start-up and operation of the sequential protection at M during two-phase metallic fault

[0129]

[0130] If a fault occurs near the opposite end (N) within the zone, the sequential quick-acting protection at end M, because it is outside the zone of the I-stage protection, activates and sends an activation signal to the circuit breaker, ensuring that the faulty line is disconnected. If a fault occurs near the opposite end (N), the sequential quick-acting protection at end M will activate, but the local protection will return after the I-stage overcurrent protection at the opposite end activates and the corresponding circuit breaker trips. If a fault occurs far from the opposite end, the sequential quick-acting protection at end M will not activate, and the sequential quick-acting protection will not malfunction under faults outside the zone.

[0131] Therefore, this invention proposes a current amplitude differential protection criterion for active distribution networks. This criterion can be used directly as primary protection or as a backup for traditional phasor differential protection. When data synchronization is disrupted or degraded across the communication system, causing traditional phasor differential protection to be disabled, the protection can be maximized by utilizing only the amplitude information of the current data on both sides. A novel fast integrated protection scheme for active distribution networks is also proposed. This scheme can adapt to various communication and data transmission scenarios. When a communication system transmission interruption occurs, sequential fast-acting protection can be used to accelerate the traditional overcurrent protection stage II, ensuring rapid circuit breaker operation in the event of a severe line fault.

[0132] Exemplary devices

[0133] Figure 8 FIG. 1 is a schematic diagram of the structure of an active distribution network fast protection device provided by an exemplary embodiment of the present invention. Figure 8 As shown, the apparatus 800 includes:

[0134] The acquisition module 810 is used to collect the electrical quantity of each node in the distribution network in real time, where the electrical quantity includes the electrical quantity of each node itself and the electrical quantity received from the opposite node;

[0135] The judgment module 820 is used to judge whether the communication between the protection devices on both sides is normal based on the collected electrical quantities of each node;

[0136] A first calculation module 830 is configured to transmit the electrical quantity of each node to a central control decision unit of the protection device when communication between the protection devices on both sides is normal. The central control decision unit calculates the current amplitude difference based on the electrical quantity of each node.

[0137] The protection action output module 840 is used to judge whether the fault is inside or outside the zone according to the current amplitude difference and the preset amplitude differential protection criterion, and to activate the protection action output of the protection device in the event of an inside fault;

[0138] The second calculation module 850 is used to calculate the negative sequence current secondary mutation amount based on the electrical quantity of each node by the central control decision unit when the communication between the protection devices on both sides is abnormal or interrupted;

[0139] The protection acceleration action output module 860 is used to judge that it is an internal fault when the overcurrent II protection on this side continuously operates and does not return, and to protect the acceleration action output according to the secondary mutation amount of the negative sequence current and the preset overcurrent II acceleration protection criterion.

[0140] Optionally, the amplitude differential protection criterion is:

[0141]

[0142] Where, They are the current phasors detected by the protection on both sides of the line M and N, M is the sending side, N is the receiving side, I set The braking amount is the action threshold set to avoid unbalanced current.

[0143] Optionally, priority is given to ensuring that when a fault occurs outside the zone, the braking amount I set Set to:

[0144]

[0145] Where, They are the current phasors detected by the protection on both sides of line N, N is the receiving end side, K res is the reliability coefficient, ranging from 1.1 to 1.2.

[0146] Optionally, when a distribution network line fails outside the MN area, the current vectors on the sending side M and the receiving side N of the line are satisfy:

[0147]

[0148] Where, They are the current phasors detected by the protection on both sides of the line M and N, M is the sending side and N is the receiving side.

[0149] Optionally, when a fault occurs in the MN area of ​​a distribution network line, the current vectors on the sending side M and the receiving side N of the line are satisfy:

[0150]

[0151] Where, They are the current phasors detected by the protection on both sides of the line M and N, M is the sending side and N is the receiving side.

[0152] Optionally, the protection accelerated action exit conditions are: the overcurrent II stage protection continuously operates and does not return, the negative sequence current amplitude undergoes two sudden changes and the action time needs to avoid instantaneous faults.

[0153] Exemplary electronic devices

[0154] Figure 9 This is the structure of an electronic device provided by an exemplary embodiment of the present invention. Figure 9 As shown, the electronic device 90 includes one or more processors 91 and a memory 92 .

[0155] The processor 91 may be a central processing unit (CPU) or other forms of processing units having data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0156] The memory 92 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may, for example, include random access memory (RAM) and / or cache memory (cache), etc. The non-volatile memory may, for example, include read-only memory (ROM), a hard disk, a flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 91 may execute the program instructions to implement the methods of the software programs of the various embodiments of the present invention described above and / or other desired functions. In one example, the electronic device may further include: an input device 93 and an output device 94, which are interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0157] In addition, the input device 93 may also include, for example, a keyboard, a mouse, and the like.

[0158] The output device 94 can output various information to the outside. The output device 94 can include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto.

[0159] Of course, to simplify, Figure 9 Only some of the components related to the present invention in the electronic device are shown, and components such as a bus, an input / output interface, etc. are omitted. In addition, the electronic device may further include any other appropriate components according to specific application conditions.

[0160] Exemplary computer program products and computer-readable storage media

[0161] In addition to the above-mentioned methods and devices, an embodiment of the present invention may also be a computer program product, which includes computer program instructions, which, when executed by a processor, enable the processor to perform the steps of the method according to various embodiments of the present invention described in the above "Exemplary Method" section of this specification.

[0162] The computer program product may be written in any combination of one or more programming languages ​​to implement the operations of embodiments of the present invention, including object-oriented programming languages ​​such as Java, C++, and conventional procedural programming languages ​​such as C or similar programming languages. The program code may be executed entirely on the user's computing device, partially on the user's computing device, as a stand-alone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0163] In addition, an embodiment of the present invention may also be a computer-readable storage medium having computer program instructions stored thereon, which, when executed by a processor, enable the processor to execute the steps of the method according to various embodiments of the present invention described in the above "Exemplary Method" section of this specification.

[0164] The computer-readable storage medium can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can, for example, include but is not limited to a system, system or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination thereof. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof.

[0165] The basic principles of the present invention have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in the present invention are merely illustrative and non-limiting, and should not be construed as necessarily possessed by each embodiment of the present invention. Furthermore, the specific details disclosed above are provided for illustrative purposes and to facilitate understanding, and are not intended to be limiting. These details do not necessarily limit the present invention to being implemented using these specific details.

[0166] Each embodiment in this specification is described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. References to the same or similar parts between the various embodiments are sufficient. For system embodiments, since they largely correspond to method embodiments, their description is relatively simple. For relevant parts, references to the description of the method embodiments are sufficient.

[0167] The block diagrams of the devices, systems, equipment, and systems involved in the present invention are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, systems, equipment, and systems can be connected, arranged, or configured in any manner. Words such as "including," "comprising," "having," and the like are open-ended words, meaning "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or" and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0168] The method and system of the present invention may be implemented in many ways. For example, the method and system of the present invention may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above sequence of steps for the method is for illustration only, and the steps of the method of the present invention are not limited to the sequence specifically described above, unless otherwise specified. In addition, in some embodiments, the present invention may also be implemented as a program recorded in a recording medium, which includes machine-readable instructions for implementing the method according to the present invention. Thus, the present invention also covers recording media that store programs for executing the method according to the present invention.

[0169] It should also be noted that, in the system, device and method of the present invention, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent schemes of the present invention. The above description of the disclosed aspects is provided to enable any technician in this field to make or use the present invention. Various modifications to these aspects will be very obvious to those skilled in the art, and the general principles defined here can be applied to other aspects without departing from the scope of the present invention. Therefore, the present invention is not intended to be limited to the aspects shown here, but according to the widest scope consistent with the principles disclosed here and novel features.

[0170] The above description has been provided for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present invention to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A fast protection method for an active distribution network, characterized in that: include: Real-time collection of electrical quantities at each node in the distribution network, where the electrical quantities include the electrical quantities of each node itself and the electrical quantities received from the opposite nodes; Judging whether the communication between the protection devices on both sides is normal based on the electrical quantities collected at each node; When communication between the protection devices on both sides is normal, the electrical quantity of each node is transmitted to the central control decision unit of the protection device, and the central control decision unit calculates the current amplitude difference based on the electrical quantity of each node; According to the current amplitude difference and the preset amplitude differential protection criterion, the internal and external faults are judged, and in the case of internal faults, the protection device protection action output; In the event of an abnormality or interruption in communication between the protection devices on both sides, the central control decision unit calculates the negative sequence current secondary mutation amount based on the electrical quantity of each node; When the overcurrent II protection on this side continuously operates and does not return, it is determined to be an internal fault, and the protection accelerated action outlet is protected according to the negative sequence current secondary mutation amount and the preset overcurrent II accelerated protection criterion.

2. The method according to claim 1, characterized in that The amplitude differential protection criterion is: Where, They are the current phasors detected by the protection on both sides of the line M and N, M is the sending side, N is the receiving side, I set The braking amount is the action threshold set to avoid unbalanced current.

3. The method according to claim 2, characterized in that Priority is given to ensuring that when there is a fault outside the zone, the braking amount I set Set to: Where, They are the current phasors detected by the protection on both sides of line N, N is the receiving end side, K res is the reliability coefficient, ranging from 1.1 to 1.

2.

4. The method according to claim 1, wherein When a distribution network line fails outside the MN area, the current vectors on the sending side M and the receiving side N of the line satisfy: Where, They are the current phasors detected by the protection on both sides of the line M and N, M is the sending side and N is the receiving side.

5. The method according to claim 1, wherein When a fault occurs in the MN area of ​​a distribution network line, the current vectors M on the sending side and N on the receiving side of the line satisfy: Where, They are the current phasors detected by the protection on both sides of the line M and N, M is the sending side and N is the receiving side.

6. The method according to claim 1, characterized in that The protection accelerated action exit conditions are: the overcurrent II stage protection continuously operates and does not return, the negative sequence current amplitude suddenly changes twice and the action time needs to avoid instantaneous faults.

7. An active distribution network fast protection device, characterized in that: include: The acquisition module is used to collect the electrical quantities of each node in the distribution network in real time, wherein the electrical quantities include the electrical quantities of each node itself and the electrical quantities received from the opposite nodes; A judgment module, configured to judge whether the communication between the protection devices on both sides is normal based on the collected electrical quantities of each node; a first calculation module, configured to transmit the electrical quantity of each node to a central control decision unit of the protection device when communication between the protection devices on both sides is normal, and the central control decision unit calculates the current amplitude difference based on the electrical quantity of each node; A protection action output module is used to judge the internal and external faults according to the current amplitude difference and the preset amplitude differential protection criterion, and to activate the protection action output of the protection device in the event of an internal fault; A second calculation module is configured to calculate the negative sequence current secondary mutation amount according to the electrical quantity of each node by the central control decision unit when the communication between the protection devices on both sides is abnormal or interrupted; The protection acceleration action output module is used to judge that it is an internal fault when the overcurrent II protection on this side continuously operates and does not return, and to protect the acceleration action output according to the secondary mutation amount of the negative sequence current and the preset overcurrent II acceleration protection criterion.

8. The device according to claim 7, characterized in that The amplitude differential protection criterion is: Where, They are the current phasors detected by the protection on both sides of the line M and N, M is the sending side, N is the receiving side, I set The braking amount is the action threshold set to avoid unbalanced current.

9. A computer-readable storage medium, characterized in that The storage medium stores a computer program, and the computer program is used to execute the method according to any one of claims 1 to 6.

10. An electronic device, characterized in that: The electronic device comprises: processor; a memory for storing instructions executable by the processor; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method according to any one of claims 1 to 6.

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