Active power distribution network fault recovery method, apparatus and device, and storage medium

Abstract

The invention discloses an active power distribution network fault recovery method and device, equipment and a storage medium, relates to the technical field of power systems and automation thereof, can accurately identify fault properties on the basis of identifying the fault types, and improves the power supply reliability and adaptability of a power distribution network under new energy access. The method comprises the following steps: acquiring fault point current information and / or fault point voltage information output by a distributed power supply in an island state of the active power distribution network; fault type identification is carried out on the fault point according to the fault point current information and / or the fault point voltage information, fault types are obtained, and the fault types at least comprise a low-resistance grounding short circuit fault, a high-resistance grounding short circuit fault and an interphase short circuit fault; carrying out fault property identification on the fault category to obtain a fault continuous feature; and determining a fault recovery strategy according to the fault type and the fault continuous characteristic, and carrying out fault recovery on the active power distribution network through the fault recovery strategy.

Description

Technical Field

[0001] This application relates to the field of power systems and their automation technology, and in particular to an active distribution network fault recovery method, device, equipment and storage medium. Background Technology

[0002] Energy activities are the primary source of carbon emissions, and optimizing the energy structure can reduce carbon emissions at the source, which is the most crucial path to achieving the dual-carbon strategy goals. Its core lies in promoting the development and utilization of renewable energy. Against this backdrop, distributed power sources such as photovoltaic and wind power have seen a significant increase in penetration into the power system due to their environmental and economic advantages, transforming the power supply mode of the distribution network into a multi-source power supply mode. This transformation significantly affects the current distribution characteristics after a distribution network fault, directly leading to problems with traditional relay protection devices, such as failure to operate, maloperation, and failure of automatic reclosing devices, posing a significant challenge to the development of distribution network relay protection and operation control. Simultaneously, establishing a scientific active distribution network fault recovery strategy requires not only shortening the load outage time but also ensuring the system stability after distributed power sources are connected to the grid, achieving rapid grid recovery to reduce economic losses and social impacts caused by power outages. This demand has become the core driving force for technological research and development.

[0003] Traditional reclosing devices are primarily designed for fault recovery in passive distribution networks, effectively addressing their fault characteristics and improving power supply reliability. However, they cannot effectively determine the nature of faults in active distribution networks, exhibiting the following drawbacks: Firstly, the lack of a basis for reclosing operations may expose the power system to secondary fault impacts, especially in cases of permanent faults, where reclosing failure can lead to a drop in secondary bus voltage. Secondly, traditional reclosing devices typically have an operating delay of 1.2 seconds, extending the duration of load outages. Furthermore, with the large-scale integration of distributed generation (DG) sources, traditional reclosing devices and DG sources exhibit incompatibility in terms of low-voltage ride-through capabilities. In the event of a fault, simply disconnecting all DG sources, while temporarily restoring the distribution network to passive operation to accommodate traditional protection, wastes the DG's ability to support system voltage, negatively impacting grid stability. Conversely, retaining DG connections allows the traditional reclosing logic to disconnect DG from the grid, further exacerbating power supply problems.

[0004] To address the aforementioned problems with traditional reclosing, related technologies can employ adaptive reclosing strategies. After a fault occurs, the nature of the fault is identified to determine whether a reclosing operation should be performed. Currently, fault identification methods are mainly divided into two categories: one is based on arc characteristic analysis, comparing transient and permanent faults by classifying arc waveforms and durations. However, the physical process of the arc is affected by environmental factors, exhibiting complexity and dynamic variability. The other is voltage recovery monitoring, which uses the voltage recovery at the fault point as a standard to determine whether the fault has been cleared. However, the voltage recovery speed varies greatly, easily leading to false fault identification. Overall, neither of these two methods can fully meet the complex requirements of active power distribution in the fault identification process. Summary of the Invention

[0005] In view of this, this application provides an active power distribution network fault recovery method, device, equipment and storage medium, the main purpose of which is to solve the problem that active power distribution network fault recovery is difficult to fully meet the complex needs of active power distribution in the fault identification process.

[0006] According to the first aspect of this application, an active power distribution network fault recovery method is provided, comprising: Acquire fault point current and / or fault point voltage information of distributed generation output in islanded state of active distribution network; Based on the fault point current information and / or fault point voltage information, the fault point is identified to obtain the fault category. The fault type includes at least low-resistance ground short circuit fault, high-resistance ground short circuit and phase-to-phase short circuit fault. The fault type is identified to obtain the fault persistence characteristics; A fault recovery strategy is determined based on the fault type and the fault persistence characteristics, so as to restore the active distribution network through the fault recovery strategy.

[0007] Furthermore, before identifying the fault type and obtaining the fault category based on the fault point current information and / or fault point voltage information, the method further includes: Based on the current and / or voltage characteristics of the fault point, fault types and first judgment conditions applicable to different fault types are constructed respectively. The fault types include at least low-resistance ground short circuit fault, high-resistance ground short circuit and phase-to-phase short circuit fault. Accordingly, the step of identifying the fault type of the fault point based on the fault point current information and / or fault point voltage information to obtain the fault category includes: Extract fault point current and / or voltage features based on the fault point current information and / or fault point voltage information; If the current and / or voltage characteristics at the fault point meet the first determination condition, then the fault type at the fault point is determined to be a low-resistance ground short-circuit fault. If the current and / or voltage characteristics at the fault point do not meet the first determination condition, then the fault type at the fault point is determined to be a high-resistance ground short circuit or a phase-to-phase short circuit fault.

[0008] Furthermore, the first determination condition is calculated using the following formula: for , ,have

[0009] in, For any phase in a three-phase power supply system, The time when the fault occurred. This is the first time interval after the fault. This is the second time interval after the fault occurred; The order of the voltage harmonic components; For the first Phase voltage at time No. Instantaneous value of the subharmonic; For this harmonic component at time... The instantaneous value; For the first Weighting coefficients for subharmonic components; For the first Attenuation coefficient of subharmonic components; It is an exponentially decaying term; The system stability coefficient; This is the system's rated voltage; in, This is a load impact correction item; For the system The bar appears at the time The sum of the total output currents; This refers to the system's rated capacity. The load factor is specifically the ratio of the total output current to the system's rated capacity.

[0010] Furthermore, before identifying the fault nature of the fault category to obtain the fault persistence characteristics, the method further includes: Based on the current and / or voltage characteristics at the fault point, a second judgment condition and a third judgment condition are constructed respectively. The second judgment condition is used to identify the fault persistence characteristics of low-resistance ground short circuit faults, and the third judgment condition is used to identify the fault persistence of high-resistance ground short circuit and phase-to-phase short circuit faults. Accordingly, the step of identifying the nature of the fault category to obtain the fault persistence characteristics includes: Based on the identification of a low-resistance ground fault, if the current and / or voltage characteristics at the fault point meet the second determination condition, the low-resistance ground fault is determined to be a transient fault; otherwise, the low-resistance ground fault is determined to be a permanent fault. Based on the identification of high-resistance ground faults and phase-to-phase short circuits, if the current and / or voltage characteristics at the fault point meet the third judgment condition, then the high-resistance ground faults and phase-to-phase short circuits are determined to be transient faults; otherwise, the high-resistance ground faults and phase-to-phase short circuits are determined to be permanent faults.

[0011] Furthermore, the second determination condition is calculated using the following formula: for ,have:

[0012] in, This is the second time interval after the fault occurred. This is the end time of the transient process; For the first The influence coefficient of current on voltage amplitude under subharmonics; For the first Instantaneous value of the inflow current at the node; The system stability coefficient; This is the system's rated voltage; in, This is a correction term for the impact of active power on the load. For the system The sum of the total active power of each load; This refers to the system's rated capacity. The load factor is specifically the ratio of the total output current to the system's rated capacity.

[0013] Furthermore, the third determination condition is calculated using the following formula:

[0014]

[0015] in, This represents the average value of the voltage across all phases.

[0016] Further, the step of determining a fault recovery strategy based on the fault type and the fault persistence characteristics, and then performing fault recovery on the active distribution network using the fault recovery strategy, includes: When the fault point is determined to be a transient fault under the fault type, the circuit breaker on the left side of the fault area is directly closed by reclosing and shutting off the circuit breaker, so as to restore the active distribution network through the reclosing and shutting off the circuit breaker. When the fault point is determined to be a permanent fault under the fault type, the circuit breaker on the right side of the fault is disconnected using the blocking reclosing operation, so as to restore the active distribution network through the blocking reclosing operation.

[0017] According to a second aspect of this application, an active power distribution network fault recovery device is provided, comprising: The acquisition unit is used to acquire fault point current information and / or fault point voltage information of the distributed power source output in the islanded state of the active distribution network. The first identification unit is used to identify the fault type of the fault point based on the fault point current information and / or fault point voltage information, and obtain the fault category. The fault type includes at least low-resistance ground short circuit fault, high-resistance ground short circuit and phase-to-phase short circuit fault. The second identification unit is used to identify the nature of the fault category and obtain the fault persistence characteristics. The fault recovery unit is used to determine a fault recovery strategy based on the fault type and the fault persistence characteristics, so as to perform fault recovery on the active distribution network through the fault recovery strategy.

[0018] Furthermore, the device also includes: The first construction unit is used to construct fault types and first judgment conditions applicable to different fault types based on the fault point current and / or fault point voltage characteristics before the fault type identification is performed on the fault point based on the fault point current information and / or fault point voltage information to obtain the fault category. The fault types include at least low-resistance ground short circuit fault, high-resistance ground short circuit and phase-to-phase short circuit fault. Accordingly, the first identification unit is specifically used for: Extract fault point current and / or voltage features based on the fault point current information and / or fault point voltage information; If the current and / or voltage characteristics at the fault point meet the first determination condition, then the fault type at the fault point is determined to be a low-resistance ground short-circuit fault. If the current and / or voltage characteristics at the fault point do not meet the first determination condition, then the fault type at the fault point is determined to be a high-resistance ground short circuit or a phase-to-phase short circuit fault.

[0019] Furthermore, the first determination condition is calculated using the following formula: for , ,have

[0020] in, For any phase in a three-phase power supply system, The time when the fault occurred. This is the first time interval after the fault. This is the second time interval after the fault occurred; The order of the voltage harmonic components; For the first Phase voltage at time No. Instantaneous value of the subharmonic; For this harmonic component at time... The instantaneous value; For the first Weighting coefficients for subharmonic components; For the first Attenuation coefficient of subharmonic components; It is an exponentially decaying term; The system stability coefficient; This is the system's rated voltage; in, This is a load impact correction item; For the system The bar appears at the time The sum of the total output currents; This refers to the system's rated capacity. The load factor is specifically the ratio of the total output current to the system's rated capacity.

[0021] Furthermore, the device also includes: The second construction unit is used to identify the fault nature of the fault category and, before obtaining the fault persistence characteristics, construct a second judgment condition and a third judgment condition based on the fault point current and / or voltage characteristics. The second judgment condition is used to identify the fault persistence characteristics of low-resistance ground short circuit faults, and the third judgment condition is used to identify the fault persistence of high-resistance ground short circuit and phase-to-phase short circuit faults. Accordingly, the second identification unit is specifically used for: Based on the identification of a low-resistance ground fault, if the current and / or voltage characteristics at the fault point meet the second determination condition, the low-resistance ground fault is determined to be a transient fault; otherwise, the low-resistance ground fault is determined to be a permanent fault. Based on the identification of high-resistance ground faults and phase-to-phase short circuits, if the current and / or voltage characteristics at the fault point meet the third judgment condition, then the high-resistance ground faults and phase-to-phase short circuits are determined to be transient faults; otherwise, the high-resistance ground faults and phase-to-phase short circuits are determined to be permanent faults.

[0022] Furthermore, the second determination condition is calculated using the following formula: for ,have:

[0023] in, This is the second time interval after the fault occurred. This is the end time of the transient process; For the first The influence coefficient of current on voltage amplitude under subharmonics; For the first Instantaneous value of the inflow current at the node; The system stability coefficient; This is the system's rated voltage; in, This is a correction term for the impact of active power on the load. For the system The sum of the total active power of each load; This refers to the system's rated capacity. The load factor is specifically the ratio of the total output current to the system's rated capacity.

[0024] Furthermore, the third determination condition is calculated using the following formula:

[0025]

[0026] in, This represents the average value of the voltage across all phases.

[0027] Furthermore, the fault recovery unit is specifically used for: When the fault point is determined to be a transient fault under the fault type, the circuit breaker on the left side of the fault area is directly closed by reclosing and shutting off the circuit breaker, so as to restore the active distribution network through the reclosing and shutting off the circuit breaker. When the fault point is determined to be a permanent fault under the fault type, the circuit breaker on the right side of the fault is disconnected using the blocking reclosing operation, so as to restore the active distribution network through the blocking reclosing operation.

[0028] According to a third aspect of this application, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method described in the first aspect above.

[0029] According to a fourth aspect of this application, a readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the first aspect above.

[0030] By employing the above technical solution, this application provides an active distribution network fault recovery method, apparatus, equipment, and storage medium. Compared with the current method of using adaptive reclosing strategies for fault recovery in active distribution networks, this application acquires fault point current and / or fault point voltage information of the distributed generation output in the islanded state of the active distribution network; identifies the fault type based on the fault point current and / or fault point voltage information to obtain the fault category, which includes at least low-resistance ground short-circuit faults, high-resistance ground short-circuit faults, and phase-to-phase short-circuit faults; identifies the fault nature of the fault category to obtain the fault persistence characteristics; and determines a fault recovery strategy based on the fault type and fault persistence characteristics to perform fault recovery on the active distribution network. The entire process, based on the identified fault type, can accurately identify the fault nature and more effectively adjust the operation mode of the distribution network to achieve rapid power restoration and improve the power supply reliability and adaptability of the distribution network under the access of new energy sources.

[0031] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0032] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart illustrating an active power distribution network fault recovery method according to an embodiment of this application; Figure 2 This is a flowchart illustrating an active power distribution network fault recovery method in another embodiment of this application; Figure 3 This is a schematic diagram of the fault nature identification process in one embodiment of this application; Figure 4 This is a flowchart illustrating a fault recovery strategy in one embodiment of this application; Figure 5 This is a schematic diagram of the structure of an active power distribution network fault recovery device in one embodiment of this application; Figure 6 This is a schematic diagram of the device structure of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0033] The invention will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are described merely to enable those skilled in the art to better understand and thus implement the invention, and are not intended to imply any limitation on the scope of the invention.

[0034] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment". The term "another embodiment" is to be interpreted as "at least one other embodiment".

[0035] Related technologies can utilize adaptive reclosing strategies to determine whether to perform a reclosing operation after a fault occurs by identifying the fault's nature. Currently, fault identification methods are mainly divided into two categories: one is based on arc characteristic analysis, comparing transient and permanent faults by classifying arc waveforms and durations; however, the physical process of the arc is affected by environmental factors, exhibiting complexity and dynamic variability. The other is voltage recovery monitoring, which uses the detection of voltage recovery at the fault point as a standard to determine whether the fault has been cleared; however, the voltage recovery speed varies greatly, easily leading to false fault identification. Overall, neither of these two methods can fully meet the complex needs of active power distribution in the fault identification process.

[0036] To address this problem, this embodiment provides an active power distribution network fault recovery method, such as... Figure 1 As shown, it includes the following steps: 101. Obtain fault point current information and / or fault point voltage information of distributed generation output in islanded state of active distribution network.

[0037] In this embodiment, an active distribution network in islanded mode refers to an active distribution network (a distribution network connected to distributed power sources such as photovoltaics, wind power, and energy storage) that is completely disconnected from the main grid, relying solely on distributed power sources within the region to supply power to the loads, forming an independently operating small-scale power supply system. Its core characteristics are physical disconnection from the main grid, distributed power sources as the sole power source, the need to maintain stable power / voltage / frequency, and a clear electrical isolation boundary.

[0038] Specifically, by synchronously collecting data from front-end nodes, measurement points can be deployed at locations such as the distributed power source outlet, grid connection point, both sides of the line sectionalizing switch, load concentration point, and fault recording device. Parameters are then collected at the measurement points, mainly including three-phase circuit, three-phase voltage, and zero-sequence current. The data collection covers the period from 0.1 seconds before the fault to 0.5 seconds after the fault. Then, the fault point current information and / or fault point voltage information are derived through algorithm model deduction.

[0039] One algorithmic derivation method involves decomposing the measurable three-phase electrical quantities into positive-sequence, negative-sequence, and zero-sequence components using the symmetrical component method. Combining this with the line's resistance / reactance per unit length and the distance to the fault point, the sequence components at the fault point are derived. These are then synthesized into three-phase currents / voltages to obtain the fault point current information and / or fault point voltage information. Another algorithmic derivation method involves calculating the steady-state and attenuation components of the fault current using formulas based on the input inverter DC bus capacitance, the voltage outer loop PI parameters, and the pre-fault output (P / Q), thereby obtaining the fault point current information and / or fault point voltage information.

[0040] 102. Based on the fault point current information and / or fault point voltage information, identify the fault type of the fault point to obtain the fault category.

[0041] The fault types include at least low-resistance ground faults, high-resistance ground faults, and phase-to-phase faults. Specifically, a two-level identification logic can be used to classify faults by zero-sequence components and to further subdivide them by amplitude characteristics. This is combined with a comparison of key indicators of the fault point current / voltage with thresholds to identify different fault types, while also clarifying the essential characteristics and electrical performance of each fault type.

[0042] For low-resistance grounding short-circuit faults, the fault point is connected to the ground through low resistance, forming a phase-to-ground short-circuit loop. This is often caused by line breakage to ground, equipment casing grounding short circuit, etc. The fault current is not limited, but is determined by the system capacity. The voltage drop is significant, and the zero-sequence protection will act quickly. If it is not cleared in time, it may damage the equipment.

[0043] For high-resistance grounding short-circuit faults, the fault point is connected to the ground through high resistance. The phase-to-ground loop resistance is large, and it is often caused by trees connected to the line, flashover of insulators, etc. The fault current is limited by high resistance and has a small amplitude. The voltage drop is gradual, and traditional protection is prone to missing the fault. It is necessary to combine it with harmonic distortion rate for auxiliary identification.

[0044] For phase-to-phase short-circuit faults, the fault path only occurs between conductors of different phases, such as phase A-phase B or phase A-phase B-phase C. No ground is involved in forming the loop, and this is a direct phase-to-phase short circuit. It is often caused by exposed conductor collisions or equipment phase-to-phase insulation breakdown. The fault current is large and concentrated between the faulty phases, which will quickly trigger phase-to-phase protection, resulting in a significant impact on the equipment.

[0045] Specifically, in the process of fault type identification, the voltage of at least one phase on the right side of the circuit breaker can be determined based on the fault current information and / or fault voltage information. If the voltage of at least one phase on the right side of the circuit breaker meets the condition that the fault phase voltage is less than the set value and drops sharply, then the fault type of the fault point is determined to be a low-resistance ground fault. If the voltage of at least one phase on the right side of the circuit breaker does not meet the condition that the fault phase voltage is less than the set value and drops sharply, then the fault type of the fault point is determined to be a high-resistance ground fault or a phase-to-phase short circuit fault.

[0046] 103. The fault type is identified to obtain the fault persistence characteristics.

[0047] In this embodiment, the essence of the fault nature is whether the fault characteristics persist. One type of fault nature is a transient fault, that is, the fault characteristics (such as voltage drop, current abnormality, zero sequence component) disappear on their own in a short time and the insulation of the fault point is restored; the other type is a permanent fault, that is, the fault characteristics persist or reappear rapidly after disappearing and the insulation of the fault point cannot be restored on its own.

[0048] Specifically, based on the identified fault type, the fault type can be determined as transient or permanent by dynamically changing fault characteristics and using a time threshold. For low-resistance ground faults, if the duration of the fault phase current and voltage is less than a first set value, and then the voltage / current automatically recovers to the rated range and the zero-sequence component disappears, the low-resistance ground fault is determined to be transient; otherwise, it is determined to be permanent. Alternatively, if the same voltage / current anomaly reappears after reclosing, and the zero-sequence component persists, the low-resistance ground fault is also determined to be permanent. For high-resistance ground faults, if the duration of the fault phase voltage and zero-sequence component is less than a second set value, and then all indicators return to normal, the high-resistance ground fault is determined to be transient; otherwise, it is determined to be permanent. Alternatively, if the anomaly persists after fluctuations, the high-resistance ground fault is also determined to be permanent. For phase-to-phase short-circuit faults, if the duration of the fault phase voltage and fault current is less than the third set value, and the phase-to-phase voltage subsequently recovers without any residual zero-sequence component, then the high-resistance ground fault is determined to be a transient fault, and the phase-to-phase short-circuit fault is determined to be a transient fault. Otherwise, the phase-to-phase short-circuit fault is determined to be a permanent fault. Alternatively, if the same voltage drop and large current reappear immediately after reclosing without any signs of self-recovery, the phase-to-phase short-circuit fault is also determined to be a permanent fault.

[0049] 104. Determine a fault recovery strategy based on the fault type and the fault persistence characteristics, so as to perform fault recovery on the active distribution network through the fault recovery strategy.

[0050] Understandably, transient faults will disappear on their own within a short time, and the insulation at the fault point can be restored. The core of the corresponding fault recovery strategy is rapid reclosing, without the need for isolation. Permanent faults, on the other hand, have persistent or recurring fault characteristics, and the fault point cannot heal itself. The core of the corresponding fault recovery strategy is blocking reclosing and switching power from the tie switch.

[0051] For transient low-resistance ground faults, the fault recovery strategy may include the following operations: immediately close the circuit breaker on the left side of the fault and initiate a reclosing operation; within 100ms after successful reclosing, restore the distributed power supply to the grid in the order of photovoltaic power first, then wind power, and complete the recovery if no abnormalities are detected for 3 seconds. For transient high-resistance ground faults, the fault recovery strategy may include the following operations: set a 0.5s delay before reclosing the circuit breaker on the left side of the fault; after reclosing, restore the light load first, then gradually load the heavy load, and monitor the harmonic distortion rate simultaneously. For transient phase-to-phase short-circuit faults, the fault recovery strategy may include the following operations: immediately reclose the circuit breaker on the left side of the fault; increase the output of the distributed power supply in a 20% / s gradient, perform insulation monitoring on the faulty phase-to-phase lines for 10 seconds, and restore full load if no abnormalities are detected.

[0052] For permanent low-resistance ground faults, the fault recovery strategy may include the following operations: blocking reclosing, disconnecting the circuit breaker on the right side of the fault to isolate the fault point; closing the adjacent tie switch to transfer the load in the non-faulty area to the standby line; and gradually increasing the capacity of the distributed power source to the grid at 50% of its rated power. For permanent high-resistance ground faults, the fault recovery strategy may include the following operations: disconnecting both sides of the faulty section with a sectionalizing switch to isolate only the faulty section; transferring the load through the nearest tie switch, and temporarily disconnecting 30% of the non-critical load if the capacity is insufficient; and continuously monitoring the zero-sequence component after recovery to confirm complete fault isolation. For permanent phase-to-phase faults, the fault recovery strategy may include the following operations: urgently disconnecting the circuit breakers on both sides of the faulty line to quickly isolate the fault; closing the tie switch to transfer the full load to the standby line; and restoring the distributed power source to the grid in batches after the voltage / frequency stabilizes.

[0053] The active distribution network fault recovery method provided in this application, compared with the current method of using adaptive reclosing strategies for fault recovery in active distribution networks, obtains fault point current and / or fault point voltage information of distributed generation output in islanded state of the active distribution network; identifies the fault type based on the fault point current and / or fault point voltage information to obtain the fault category, which includes at least low-resistance ground short-circuit fault, high-resistance ground short-circuit fault, and phase-to-phase short-circuit fault; identifies the fault nature based on the fault category to obtain fault persistence characteristics; and determines a fault recovery strategy based on the fault type and fault persistence characteristics to recover the active distribution network from faults. The entire process, based on the identified fault type, can accurately identify the fault nature and more effectively adjust the operation mode of the distribution network to achieve rapid power restoration and improve the power supply reliability and adaptability of the distribution network under the access of new energy sources.

[0054] In practical applications, current and voltage are the most direct electrical manifestations of faults. Different faults have different energy transfer paths and impedance characteristics, resulting in unique current / voltage characteristics. Furthermore, such as... Figure 2 As shown, prior to step 102, the above method further includes the following steps: 105. Based on the current and / or voltage characteristics at the fault point, construct fault types and first judgment conditions applicable to different fault types.

[0055] Accordingly, step 102 above includes the following steps: 102-1. Extract the fault point current and / or voltage characteristics based on the fault point current information and / or fault point voltage information.

[0056] 102-2. If the current and / or voltage characteristics of the fault point meet the first determination condition, then the fault type of the fault point is determined to be a low-resistance ground short-circuit fault.

[0057] 102-3. If the current and / or voltage characteristics of the fault point do not meet the first judgment condition, then the fault type of the fault point is determined to be a high-resistance ground short circuit or a phase-to-phase short circuit fault.

[0058] The fault types include at least low-resistance ground faults, high-resistance ground faults, and phase-to-phase faults. Since the core characteristic carriers of different fault types differ—the core characteristic of ground faults (low-resistance / high-resistance) lies in zero-sequence current / voltage, while the core characteristic of phase-to-phase faults lies in phase-to-phase voltage / fault current—the corresponding identification requirements also differ. For example, in islanded scenarios with distributed power supply, the fault current amplitude is lower than that of the main grid, and the current threshold for low-resistance ground faults can be adjusted accordingly. To more accurately adapt to the identification needs of different scenarios, constructing separate criteria allows each judgment condition to better fit the essence of the specific fault, improving identification accuracy.

[0059] In one possible implementation of this embodiment, the first determination condition is calculated using the following formula: for , ,have

[0060] in, For any phase in a three-phase power supply system, The time when the fault occurred. This is the first time interval after the fault. This is the second time interval after the fault occurred; The order of the voltage harmonic components; For the first Phase voltage at time No. Instantaneous value of the subharmonic; For this harmonic component at time... The instantaneous value; For the first Weighting coefficients for subharmonic components; For the first Attenuation coefficient of subharmonic components; It is an exponentially decaying term; The system stability coefficient; This is the system's rated voltage; in, This is a load impact correction item; For the system The bar appears at the time The sum of the total output currents; This refers to the system's rated capacity. The load factor is specifically the ratio of the total output current to the system's rated capacity.

[0061] To make fault identification more rigorous and adaptable, based on the identified fault type, the duration and recovery trend of the fault can be quantified to accurately identify the persistent characteristics of the fault. Furthermore, such as... Figure 2 As shown, prior to step 103, the above method further includes the following steps: 106. Based on the current and / or voltage characteristics at the fault point, construct the second and third judgment conditions respectively.

[0062] Accordingly, step 103 above includes the following steps: 103-1. Based on the identification of a low-resistance ground fault, if the current and / or voltage characteristics at the fault point meet the second judgment condition, the low-resistance ground fault is determined to be a transient fault; otherwise, the low-resistance ground fault is determined to be a permanent fault.

[0063] 103-2. Based on the identification of high-resistance ground short circuit and phase-to-phase short circuit faults, if the current and / or voltage characteristics of the fault point meet the third judgment condition, then the high-resistance ground short circuit and phase-to-phase short circuit faults are determined to be transient faults; otherwise, the high-resistance ground short circuit and phase-to-phase short circuit faults are determined to be permanent faults.

[0064] In one possible implementation of this embodiment, the second determination condition is calculated using the following formula: for ,have:

[0065] in, This is the second time interval after the fault occurred. This is the end time of the transient process; For the first The influence coefficient of current on voltage amplitude under subharmonics; For the first Instantaneous value of the inflow current at the node; The system stability coefficient; This is the system's rated voltage; in, This is a correction term for the impact of active power on the load. For the system The sum of the total active power of each load; This refers to the system's rated capacity. The load factor is specifically the ratio of the total output current to the system's rated capacity.

[0066] In one possible implementation of this embodiment, the third determination condition is calculated using the following formula:

[0067]

[0068] in, This represents the average value of the voltage across all phases.

[0069] In practical applications, the specific implementation process for the above-mentioned fault nature identification can be found in [link to relevant documentation]. Figure 3 As shown, the fault determination process is initiated first. Then, the voltage data on the right side of the circuit breaker is determined to identify the fault point. It is determined whether at least one phase voltage meets the first determination condition. If so, the fault point is determined to be a low-resistance ground fault; otherwise, the fault point is determined to be a high-resistance ground fault and a phase-to-phase fault. Next, for the low-resistance ground fault, it is determined whether the voltage difference meets the second determination condition. If so, the low-resistance ground fault is determined to be a transient fault; otherwise, it is determined to be a permanent fault. Similarly, for the high-resistance ground fault and phase-to-phase fault, it is determined whether the voltage difference meets the third determination condition. If so, the high-resistance ground fault and phase-to-phase fault are determined to be transient faults; otherwise, they are determined to be permanent faults.

[0070] Based on the fault persistence characteristics under different fault types described above, step 104 includes the following steps: When the fault persistence characteristic of the fault point under the fault type is determined to be a transient fault, the circuit breaker on the left side of the fault area is directly closed using a reclosing operation to restore the active distribution network through the reclosing operation. When the fault persistence characteristic of the fault point under the fault type is determined to be a permanent fault, the circuit breaker on the right side of the fault is opened using a blocking reclosing operation to restore the active distribution network through the blocking reclosing operation.

[0071] In practical application scenarios, the specific implementation process of the above fault recovery strategy can be found in [link to relevant documentation]. Figure 4As shown, the fault recovery process is initiated first. When a fault occurs, the left-side circuit breaker trips first. Then, the voltage transformer on the right side of the faulty right-side circuit breaker is checked to collect voltage data on the right side of the faulty right-side circuit breaker. It is determined whether the voltage meets the first judgment condition. If so, the fault point is determined to be a low-resistance ground fault; otherwise, the fault point is determined to be a high-resistance ground fault and a phase-to-phase short circuit fault. Next, for the low-resistance ground fault, it is determined whether the voltage difference meets the second judgment condition. If so, the low-resistance ground fault is determined to be a transient fault, and immediate reclosing is executed, closing the faulty left-side circuit breaker. Power supply to the distribution network is then restored, and the process ends. Otherwise, the low-resistance ground fault is determined to be a permanent fault, and reclosing is blocked, opening the faulty right-side circuit breaker and closing the tie switch. Power supply to the distribution network is then restored, and the process ends. Similarly, for high-resistance ground faults and phase-to-phase faults, it is determined whether the voltage difference meets the third criterion. If so, the high-resistance ground fault and phase-to-phase fault are determined to be transient faults, and immediate reclosing is performed to close the circuit breaker on the left side of the fault. After that, the power distribution network is restored, and the process ends. Otherwise, the high-resistance ground fault and phase-to-phase fault are determined to be permanent faults, and reclosing is blocked to open the circuit breaker on the right side of the fault and close the tie switch. After that, the power distribution network is restored, and the process ends.

[0072] Furthermore, as a specific implementation of the above method, this application embodiment provides an active power distribution network fault recovery device, such as... Figure 5 As shown, the device includes: an acquisition unit 21, a first identification unit 22, a second identification unit 23, and a fault recovery unit 24.

[0073] Acquisition unit 21 is used to acquire fault point current information and / or fault point voltage information of distributed power source output in islanded state of active distribution network; The first identification unit 22 is used to identify the fault type of the fault point according to the fault point current information and / or fault point voltage information, and obtain the fault category. The fault type includes at least low-resistance ground short circuit fault, high-resistance ground short circuit and phase-to-phase short circuit fault. The second identification unit 23 is used to identify the nature of the fault category and obtain the fault persistence characteristics. The fault recovery unit 24 is used to determine a fault recovery strategy based on the fault type and the fault persistence characteristics, so as to perform fault recovery on the active distribution network through the fault recovery strategy.

[0074] The active distribution network fault recovery device provided in this invention, compared with the current method of using adaptive reclosing strategies for fault recovery in active distribution networks, acquires fault point current and / or fault point voltage information of distributed power sources in islanded state of the active distribution network; identifies the fault type based on the fault point current and / or fault point voltage information to obtain the fault category, which includes at least low-resistance ground short-circuit fault, high-resistance ground short-circuit fault, and phase-to-phase short-circuit fault; identifies the fault nature of the fault category to obtain the fault persistence characteristics; and determines the fault recovery strategy based on the fault type and fault persistence characteristics to perform fault recovery on the active distribution network. The entire process, based on the identified fault type, can accurately identify the fault nature and more effectively adjust the operation mode of the distribution network to achieve rapid power restoration and improve the power supply reliability and adaptability of the distribution network under the access of new energy sources.

[0075] In specific application scenarios, the device further includes: The first construction unit is used to construct fault types and first judgment conditions applicable to different fault types based on the fault point current and / or fault point voltage characteristics before the fault type identification is performed on the fault point based on the fault point current information and / or fault point voltage information to obtain the fault category. The fault types include at least low-resistance ground short circuit fault, high-resistance ground short circuit and phase-to-phase short circuit fault. Accordingly, the first identification unit is specifically used for: Extract fault point current and / or voltage features based on the fault point current information and / or fault point voltage information; If the current and / or voltage characteristics at the fault point meet the first determination condition, then the fault type at the fault point is determined to be a low-resistance ground short-circuit fault. If the current and / or voltage characteristics at the fault point do not meet the first determination condition, then the fault type at the fault point is determined to be a high-resistance ground short circuit or a phase-to-phase short circuit fault.

[0076] In specific application scenarios, the first determination condition is calculated using the following formula: for , ,have

[0077] in, For any phase in a three-phase power supply system, The time when the fault occurred. This is the first time interval after the fault. This is the second time interval after the fault occurred; The order of the voltage harmonic components; For the first Phase voltage at time No. Instantaneous value of the subharmonic; For this harmonic component at time... The instantaneous value; For the first Weighting coefficients for subharmonic components; For the first Attenuation coefficient of subharmonic components; It is an exponentially decaying term; The system stability coefficient; This is the system's rated voltage; in, This is a load impact correction item; For the system The bar appears at the time The sum of the total output currents; This refers to the system's rated capacity. The load factor is specifically the ratio of the total output current to the system's rated capacity.

[0078] In specific application scenarios, the device further includes: The second construction unit is used to identify the fault nature of the fault category and, before obtaining the fault persistence characteristics, construct a second judgment condition and a third judgment condition based on the fault point current and / or voltage characteristics. The second judgment condition is used to identify the fault persistence characteristics of low-resistance ground short circuit faults, and the third judgment condition is used to identify the fault persistence of high-resistance ground short circuit and phase-to-phase short circuit faults. Accordingly, the second identification unit is specifically used for: Based on the identification of a low-resistance ground fault, if the current and / or voltage characteristics at the fault point meet the second determination condition, the low-resistance ground fault is determined to be a transient fault; otherwise, the low-resistance ground fault is determined to be a permanent fault. Based on the identification of high-resistance ground faults and phase-to-phase short circuits, if the current and / or voltage characteristics at the fault point meet the third judgment condition, then the high-resistance ground faults and phase-to-phase short circuits are determined to be transient faults; otherwise, the high-resistance ground faults and phase-to-phase short circuits are determined to be permanent faults.

[0079] In specific application scenarios, the second determination condition is calculated using the following formula: for ,have:

[0080] in, This is the second time interval after the fault occurred. This is the end time of the transient process; For the first The influence coefficient of current on voltage amplitude under subharmonics; For the first Instantaneous value of the inflow current at the node; The system stability coefficient; This is the system's rated voltage; in, This is a correction term for the impact of active power on the load. For the system The sum of the total active power of each load; This refers to the system's rated capacity. The load factor is specifically the ratio of the total output current to the system's rated capacity.

[0081] In specific application scenarios, the third determination condition is calculated using the following formula:

[0082]

[0083] in, This represents the average value of the voltage across all phases.

[0084] In specific application scenarios, the fault recovery unit is specifically used for: When the fault point is determined to be a transient fault under the fault type, the circuit breaker on the left side of the fault area is directly closed by reclosing and shutting off the circuit breaker, so as to restore the active distribution network through the reclosing and shutting off the circuit breaker. When the fault point is determined to be a permanent fault under the fault type, the circuit breaker on the right side of the fault is disconnected using the blocking reclosing operation, so as to restore the active distribution network through the blocking reclosing operation.

[0085] It should be noted that other corresponding descriptions of the functional units involved in the active distribution network fault recovery device provided in this embodiment can be found in [reference]. Figure 1 The corresponding description in [the document] will not be repeated here.

[0086] Based on the above, Figure 1 Accordingly, this application embodiment also provides a storage medium storing a computer program thereon, which, when executed by a processor, implements the above-described method. Figure 1 The active power distribution network fault recovery method is shown.

[0087] Based on this understanding, the technical solution of this application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, or portable hard drive) and includes several instructions to cause a computer device (such as a personal computer, server, or network device) to execute the methods described in the various implementation scenarios of this application.

[0088] Based on the above, Figure 1 The method shown, and Figure 5 To achieve the above objectives, this application also provides a physical device for active power distribution network fault recovery, as illustrated in the virtual device embodiment. Specifically, this device can be a computer, smartphone, tablet, smartwatch, server, or network equipment, etc. The physical device includes a storage medium and a processor; the storage medium stores a computer program; the processor executes the computer program to achieve the above-described... Figure 1 The active power distribution network fault recovery method is shown.

[0089] Optionally, the physical device may also include a user interface, a network interface, a camera, radio frequency (RF) circuitry, sensors, audio circuitry, a Wi-Fi module, etc. The user interface may include a display screen, input units such as a keyboard, etc., and optional user interfaces may also include USB interfaces, card reader interfaces, etc. The network interface may optionally include standard wired interfaces, wireless interfaces (such as Wi-Fi interfaces), etc.

[0090] In an exemplary embodiment, see Figure 6 The aforementioned physical devices include a communication bus, a processor, a memory, and a communication interface. They may also include input / output interfaces and a display device. The various functional units can communicate with each other via the bus. The memory stores computer programs, and the processor executes the programs stored in the memory to perform the active power distribution network fault recovery method described in the above embodiments.

[0091] Those skilled in the art will understand that the physical equipment structure for active power distribution network fault recovery provided in this embodiment does not constitute a limitation on the physical equipment, and may include more or fewer components, or combine certain components, or have different component arrangements.

[0092] The storage medium may also include an operating system and a network communication module. The operating system is a program that manages the hardware and software resources of the physical equipment for active power distribution network fault recovery, supporting the operation of information processing programs and other software and / or programs. The network communication module is used to enable communication between the various components within the storage medium, as well as communication with other hardware and software in the information processing physical equipment.

[0093] Through the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented using software plus necessary general-purpose hardware platforms, or it can be implemented through hardware. By applying the technical solution of this application, compared with the existing methods, this application can accurately identify the nature of the fault based on the identification of the fault type, and more effectively adjust the operation mode of the distribution network to achieve rapid power restoration and improve the power supply reliability and adaptability of the distribution network under the access of new energy sources.

[0094] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of a preferred embodiment, and the modules or processes shown in the drawings are not necessarily essential for implementing this application. Those skilled in the art will understand that the modules in the apparatus of the embodiment can be distributed within the apparatus of the embodiment as described, or can be modified to be located in one or more apparatuses different from this embodiment. The modules of the above-described embodiment can be combined into one module, or further divided into multiple sub-modules.

[0095] The serial numbers in this application are for descriptive purposes only and do not represent the superiority or inferiority of any particular implementation scenario. The above disclosures are merely a few specific implementation scenarios of this application; however, this application is not limited thereto, and any variations conceived by those skilled in the art should fall within the protection scope of this application.

Claims

1. A method for active power distribution network fault recovery, characterized in that, include: Acquire fault point current and / or fault point voltage information of distributed generation output in islanded state of active distribution network; Based on the fault point current information and / or fault point voltage information, the fault point is identified to obtain the fault category. The fault type includes at least low-resistance ground short circuit fault, high-resistance ground short circuit and phase-to-phase short circuit fault. The fault type is identified to obtain the fault persistence characteristics; A fault recovery strategy is determined based on the fault type and the fault persistence characteristics, so as to restore the active distribution network through the fault recovery strategy.

2. The method according to claim 1, characterized in that, Before identifying the fault type and obtaining the fault category based on the fault point current information and / or fault point voltage information, the method further includes: Based on the current and / or voltage characteristics of the fault point, fault types and first judgment conditions applicable to different fault types are constructed respectively. The fault types include at least low-resistance ground short circuit fault, high-resistance ground short circuit and phase-to-phase short circuit fault. Accordingly, the step of identifying the fault type of the fault point based on the fault point current information and / or fault point voltage information to obtain the fault category includes: Extract fault point current and / or voltage features based on the fault point current information and / or fault point voltage information; If the current and / or voltage characteristics at the fault point meet the first determination condition, then the fault type at the fault point is determined to be a low-resistance ground short-circuit fault. If the current and / or voltage characteristics at the fault point do not meet the first determination condition, then the fault type at the fault point is determined to be a high-resistance ground short circuit or a phase-to-phase short circuit fault.

3. The method according to claim 2, characterized in that, The first determination condition is calculated using the following formula: for , ,have in, For any phase in a three-phase power supply system, The time when the fault occurred. This is the first time interval after the fault. This is the second time interval after the fault occurred; The order of the voltage harmonic components; For the first Phase voltage at time No. Instantaneous value of the subharmonic; For this harmonic component at time... The instantaneous value; For the first Weighting coefficients for subharmonic components; For the first Attenuation coefficient of subharmonic components; It is an exponentially decaying term; The system stability coefficient; This is the system's rated voltage; in, This is a load impact correction item; For the system The bar appears at the time The sum of the total output currents; This refers to the system's rated capacity. The load factor is specifically the ratio of the total output current to the system's rated capacity.

4. The method according to claim 2, characterized in that, Before identifying the fault nature of the fault category and obtaining the fault persistence characteristics, the method further includes: Based on the current and / or voltage characteristics at the fault point, a second determination condition and a third determination condition are constructed respectively. The second determination condition is used to identify the fault persistence characteristics of low-resistance ground short-circuit faults, and the third determination condition is used to identify the fault persistence of high-resistance ground short-circuit and phase-to-phase short-circuit faults. Accordingly, the step of identifying the nature of the fault category to obtain the fault persistence characteristics includes: Based on the identification of a low-resistance ground fault, if the current and / or voltage characteristics at the fault point meet the second determination condition, the low-resistance ground fault is determined to be a transient fault; otherwise, the low-resistance ground fault is determined to be a permanent fault. Based on the identification of high-resistance ground faults and phase-to-phase short circuits, if the current and / or voltage characteristics at the fault point meet the third judgment condition, then the high-resistance ground faults and phase-to-phase short circuits are determined to be transient faults; otherwise, the high-resistance ground faults and phase-to-phase short circuits are determined to be permanent faults.

5. The method according to claim 4, characterized in that, The second determination condition is calculated using the following formula: for ,have: in, This is the second time interval after the fault occurred. This is the end time of the transient process; For the first The influence coefficient of current on voltage amplitude under subharmonics; For the first Instantaneous value of the inflow current at the node; The system stability coefficient; This is the system's rated voltage; in, This is a correction term for the impact of active power on the load. For the system The sum of the total active power of each load; This refers to the system's rated capacity. The load factor is specifically the ratio of the total output current to the system's rated capacity.

6. The method according to claim 4, characterized in that, The third determination condition is calculated using the following formula: in, This represents the average value of the voltage across all phases.

7. The method according to any one of claims 1-6, characterized in that, The step of determining a fault recovery strategy based on the fault type and the fault persistence characteristics, and then performing fault recovery on the active distribution network using the fault recovery strategy, includes: When the fault point is determined to be a transient fault under the fault type, the circuit breaker on the left side of the fault area is directly closed by reclosing and shutting off the circuit breaker, so as to restore the active distribution network through the reclosing and shutting off the circuit breaker. When the fault point is determined to be a permanent fault under the fault type, the circuit breaker on the right side of the fault is disconnected using the blocking reclosing operation, so as to restore the active distribution network through the blocking reclosing operation.

8. An active power distribution network fault recovery device, characterized in that, include: The acquisition unit is used to acquire fault point current information and / or fault point voltage information of the distributed power source output in the islanded state of the active distribution network. The first identification unit is used to identify the fault type of the fault point based on the fault point current information and / or fault point voltage information, and obtain the fault category. The fault type includes at least low-resistance ground short circuit fault, high-resistance ground short circuit and phase-to-phase short circuit fault. The second identification unit is used to identify the nature of the fault category and obtain the fault persistence characteristics. The fault recovery unit is used to determine a fault recovery strategy based on the fault type and the fault persistence characteristics, so as to perform fault recovery on the active distribution network through the fault recovery strategy.

9. The apparatus according to claim 8, characterized in that, The device further includes: The first construction unit is used to construct fault types and first judgment conditions applicable to different fault types based on the fault point current and / or fault point voltage characteristics before the fault type identification is performed on the fault point based on the fault point current information and / or fault point voltage information to obtain the fault category. The fault types include at least low-resistance ground short circuit fault, high-resistance ground short circuit and phase-to-phase short circuit fault. Accordingly, the first identification unit is specifically used for: Extract fault point current and / or voltage features based on the fault point current information and / or fault point voltage information; If the current and / or voltage characteristics at the fault point meet the first determination condition, then the fault type at the fault point is determined to be a low-resistance ground short-circuit fault. If the current and / or voltage characteristics at the fault point do not meet the first determination condition, then the fault type at the fault point is determined to be a high-resistance ground short circuit or a phase-to-phase short circuit fault.

10. The apparatus according to claim 8, characterized in that, The device further includes: The second construction unit is used to identify the fault nature of the fault category and, before obtaining the fault persistence characteristics, construct a second judgment condition and a third judgment condition based on the fault point current and / or voltage characteristics. The second judgment condition is used to identify the fault persistence characteristics of low-resistance ground short circuit faults, and the third judgment condition is used to identify the fault persistence of high-resistance ground short circuit and phase-to-phase short circuit faults. Accordingly, the second identification unit is specifically used for: Based on the identification of a low-resistance ground fault, if the current and / or voltage characteristics at the fault point meet the second determination condition, the low-resistance ground fault is determined to be a transient fault; otherwise, the low-resistance ground fault is determined to be a permanent fault. Based on the identification of high-resistance ground faults and phase-to-phase short circuits, if the current and / or voltage characteristics at the fault point meet the third judgment condition, then the high-resistance ground faults and phase-to-phase short circuits are determined to be transient faults; otherwise, the high-resistance ground faults and phase-to-phase short circuits are determined to be permanent faults.

11. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the active power distribution network fault recovery method according to any one of claims 1 to 7.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the active power distribution network fault recovery method according to any one of claims 1 to 7.

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