Fault isolation method, device, storage medium and electronic equipment for power distribution system

Abstract

The present application provides a method, device, storage medium and electronic device for fault isolation of a power distribution system, which relates to the field of power distribution technology. The method includes: when the power distribution system includes multiple power supply lines, obtaining the flow parameters of each power supply line in the power distribution system; when the flow parameters of at least one power supply line are not within the corresponding threshold range, determining that the power distribution system has a fault; when a short circuit fault occurs in the power distribution system, determining the power supply line with the largest collected current as the fault line; sending a trip signal to the circuit breaker of the fault line to control the instantaneous tripping of the circuit breaker of the fault line, thereby cutting off the connection between the fault line and the power distribution system and completing fault isolation. The method can accurately locate the fault line, isolate the fault line, and avoid damage to the equipment caused by the failure to timely remove the fault due to the refusal of the regional protection device.

Description

Technical Field

[0001] The present application relates to the field of power distribution technology, and in particular to a fault isolation method for a power distribution system, a fault isolation device for a power distribution system, a computer-readable storage medium, and an electronic device. Background Art

[0002] With the large-scale grid connection of distributed energy represented by wind power and photovoltaic power generation, the large-scale access of impact loads represented by electric vehicles, and the diversified development of distribution network user loads, however, the traditional distribution network architecture is mainly radial, adopting the "closed-loop design, open-loop operation" mode. With the high proportion of access and increasing penetration of new sources and loads, the power supply line operation and protection design of the distribution network will face huge challenges, which seriously affects the safe and stable operation of the distribution network. Energy storage technology has the ability to transfer energy flow at the time level, which can smooth system power fluctuations, reduce peaks and fill valleys, improve power quality, and improve the power grid's ability to absorb new energy. It is an effective solution to deal with the grid connection of new energy. However, limited by the radial architecture of the traditional distribution network, large-capacity energy storage currently adopts a chain power conversion topology with a single medium-voltage AC port, which is distributed and connected to different distribution networks. The distributed access solution faces problems such as large battery capacity, low system utilization, high cost, and large footprint. Compared with the flexible interconnection solution, the energy storage system does not have the real-time transfer capability of the load in the distribution network, which restricts the promotion and application of energy storage technology at the medium-voltage distribution level.

[0003] MACP-CHB-ESS interconnects multiple medium-voltage AC ports with the same large-capacity energy storage system. Due to the power interaction between multiple ports, when a power supply line fails, the voltage and current distribution characteristics under the fault state become more complex. Fault transmission will cause the voltage at the healthy port to drop, which is not conducive to system operation. Therefore, when a short-circuit fault occurs in the shared energy storage flexible interconnection equipment, the harm is not limited to the equipment itself, but will also have a profound impact on the stability and safety of the entire power system, which may lead to widespread economic losses and safety hazards. Summary of the invention

[0004] The main purpose of the present application is to provide a fault isolation method for a power distribution system, a fault isolation device for a power distribution system, a computer-readable storage medium and an electronic device, so as to at least solve the problem in the prior art that when a short circuit fault occurs in a shared energy storage flexible interconnection equipment, the fault current will increase rapidly, causing damage to the energy storage unit and the fault will spread easily.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a fault isolation method for a power distribution system is provided, wherein the power distribution system is a topology structure based on a multi-port chain battery energy storage system, the power distribution system includes at least one power supply line, and a circuit breaker is installed between the port inductance of each power supply line and a common connection point, and the method includes: when the power distribution system includes multiple power supply lines, obtaining the power flow parameters of each power supply line in the power distribution system, the power flow parameters at least including a collection current and a collection voltage; when the power flow parameters of at least one power supply line are not within the corresponding threshold range, determining that a fault has occurred in the power distribution system; when a short circuit fault occurs in the power distribution system, determining the power supply line with the largest collection current as a fault line; sending a trip signal to the circuit breaker of the fault line to control the circuit breaker of the fault line to trip instantly, so as to cut off the connection between the fault line and the power distribution system, and complete fault isolation.

[0006] Optionally, a corresponding half-bridge power flow control module is connected between the port inductor of the power supply line and the DC bus, the half-bridge power flow control module includes a first power module on the first bridge wall and a second power module on the second bridge wall, the second power module is connected in parallel with the thyristor bypass switch, and when the power flow parameter of at least one of the power supply lines is not within the corresponding threshold range, it is determined that the power distribution system has a fault, including: when the collected current of the power supply line is greater than the first protection setting value, and the zero-sequence current component of the power supply line is greater than the second protection setting value, it is determined that a short-circuit fault has occurred in the power distribution system, and all power devices in the half-bridge power flow control module are controlled to be locked, and after a dead time, the thyristor bypass switch is turned on; when the collected current of the power supply line is greater than the first protection setting value, and the zero-sequence current component of the power supply line is less than the second protection setting value, it is determined that a phase-to-phase short-circuit fault has occurred in the power distribution system; when the zero-sequence current component of the power supply line is greater than a current reference value, it is determined that a ground short-circuit fault has occurred in the power distribution system, and the current reference value is less than the first protection setting value and the second protection setting value.

[0007] Optionally, the power supply line includes a first power supply line, a second power supply line and a third power supply line. When a short circuit fault occurs in the power distribution system, before determining the power supply line with the largest collected current as the faulty line, the method further includes: when a three-phase short circuit fault occurs in the second power supply line at a historical moment, according to the first current formula and the second current formula , respectively determine the three-phase current of the first power supply line and the three-phase current of the third power supply line, wherein, is the three-phase current of the first power supply line, is the three-phase current of the third power supply line, is the equivalent electromotive force of the first power supply line, is the equivalent electromotive force of the third power supply line, is the equivalent transformer impedance of the first power supply line, is the equivalent transformer impedance of the third power supply line, is the equivalent inductance of the first power supply line, The equivalent inductance ω of the third power supply line is the angular frequency, and Lc represents the filter inductance of the power supply line; according to the KCL law, the three-phase short-circuit current of the second power supply line is determined to be the sum of the three-phase current of the first power supply line and the three-phase current of the third power supply line.

[0008] Optionally, the power distribution system includes a first power supply line, a second power supply line and a third power supply line. When a short circuit fault occurs in the power distribution system, before determining the power supply line with the largest collected current as the faulty line, the method further includes: when a two-phase short circuit fault occurs in the second power supply line at a historical moment, according to the first A-phase current positive sequence component formula The positive and negative zero-sequence phase rotation relationship of the ABC three-phase , determine the two-phase short-circuit current of the second power supply line, the two-phase short-circuit fault is a B-phase short-circuit fault and a C-phase short-circuit fault, wherein, is the positive sequence component of phase A current, is the phase A current, is the negative sequence component of phase A current, is the zero-sequence component of phase A current, is the B phase current, is the C phase current, is the rotation factor, is the positive sequence equivalent reactance of non-fault phase A, is the negative-sequence equivalent reactance of the non-fault phase A; based on the KCL law, it is determined that the B-phase short-circuit current of the second power supply line is the sum of the B-phase current of the first power supply line and the B-phase current of the third power supply line, and the C-phase short-circuit current of the second power supply line is the sum of the C-phase current of the first power supply line and the C-phase current of the third power supply line.

[0009] Optionally, the power distribution system includes a first power supply line, a second power supply line and a third power supply line. When a short circuit fault occurs in the power distribution system, before determining the power supply line with the largest collected current as the faulty line, the method further includes: when a two-phase ground short circuit fault occurs in the second power supply line at a historical moment, according to the second A phase current positive sequence component formula and the positive and negative zero-sequence phasor rotation relationship of the three-phase ABC, determine the two-phase short-circuit current of the second power supply line, the two-phase ground short-circuit fault is a B-phase ground short-circuit fault and a C-phase ground short-circuit fault, wherein, is the positive sequence current of non-fault phase A, is the equivalent electromotive force of non-fault phase A, is the positive sequence equivalent reactance of non-fault phase A, is the negative sequence equivalent reactance of non-fault phase A, is the zero-sequence equivalent reactance of non-fault phase A, is the transition resistance; based on the KCL law, it is determined that the B-phase short-circuit current of the second power supply line is the sum of the B-phase current of the first power supply line and the B-phase current of the third power supply line, and the C-phase short-circuit current of the second power supply line is the sum of the C-phase current of the first power supply line and the C-phase current of the third power supply line.

[0010] Optionally, the power distribution system includes a first power supply line, a second power supply line and a third power supply line. When a short-circuit fault occurs in the power distribution system, before determining the power supply line with the largest collected current as the faulty line, the method further includes: when a single-phase short-circuit fault occurs in the second power supply line at a historical moment, obtaining the A-phase short-circuit current of the short-circuit point on the second power supply line; according to the A-phase short-circuit current and the single-phase current formula of the short-circuit point on the second power supply line , determine the single-phase short-circuit current of the second power supply line, wherein, is the positive sequence component of phase A current, is the phase A current, is the negative sequence component of phase A current, is the zero-sequence component of the phase A current; based on the KCL law, it is determined that the single-phase short-circuit current of the second power supply line is the sum of the single-phase current of the first power supply line and the single-phase current of the third power supply line.

[0011] Optionally, obtaining the A-phase short-circuit current of the short-circuit point on the second power supply line includes: based on the A-phase short-circuit formula , determine the A-phase short-circuit current of the short-circuit point on the second power supply line, wherein, is the positive sequence current of non-fault phase A, is the negative sequence current of non-fault phase A, is the zero-sequence current of non-fault phase A, is the equivalent electromotive force of non-fault phase A, is the positive sequence equivalent reactance of non-fault phase A, is the negative sequence equivalent reactance of non-fault phase A, is the zero-sequence equivalent reactance of non-fault phase A, is the transition resistor.

[0012] According to another aspect of the present application, a fault isolation device for a power distribution system is provided, wherein the power distribution system is a topology structure based on a multi-port chain battery energy storage system, the power distribution system includes at least one power supply line, and a circuit breaker is installed between the port inductance of each power supply line and a common connection point, and the device includes: an acquisition unit, for acquiring the power flow parameters of each power supply line in the power distribution system when the power distribution system includes multiple power supply lines, the power flow parameters at least including a collection current and a collection voltage; a first determination unit, for determining that a fault has occurred in the power distribution system when the power flow parameters of at least one power supply line are not within a corresponding threshold range; a second determination unit, for determining that the power supply line with the largest collection current is a fault line when a short circuit fault occurs in the power distribution system; a fault isolation unit, for sending a trip signal to the circuit breaker of the fault line to control the circuit breaker of the fault line to trip instantly, so as to cut off the connection between the fault line and the power distribution system, and complete fault isolation.

[0013] According to another aspect of the present application, a computer-readable storage medium is provided, wherein the computer-readable storage medium includes a stored program, wherein when the program is executed, the device where the computer-readable storage medium is located is controlled to execute any one of the distribution system fault isolation methods.

[0014] According to another aspect of the present application, an electronic device is provided, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the one or more programs include a method for executing any one of the fault isolation methods of the power distribution system.

[0015] Applying the technical solution of the present application, the fault isolation method of the above-mentioned distribution system, first, when the distribution system includes multiple power supply lines, obtain the flow parameters of each power supply line in the distribution system, the flow parameters at least include the collected current and the collected voltage; when the flow parameters of at least one power supply line are not within the corresponding threshold range, determine that the distribution system has a fault; when a short circuit fault occurs in the distribution system, determine the power supply line with the largest collected current as the fault line; send a trip signal to the circuit breaker of the fault line to control the instantaneous tripping of the circuit breaker of the fault line to cut off the connection between the fault line and the distribution system, and complete the fault isolation. This method can accurately judge the fault of the shared energy storage power supply line, disconnect the system from the fault power supply line, avoid the transmission of faults between multiple power supply lines when a large disturbance occurs, affect other normal power supply lines, and reduce the impact of disturbances on the system. At the same time, this method can also ensure the safe transition of the device in the fault state, prevent the device from being in a fault state for a long time when the AC power supply line area protection refuses to operate, and cause damage to the device, and quickly cut off the connection between the device and the faulty power supply line is conducive to realizing power supply recovery and flow control after the fault, and improves the power supply reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting part of the present application are used to provide a further understanding of the present application. The exemplary embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0017] Figure 1 A hardware structure block diagram of a mobile terminal for executing a fault isolation method for a power distribution system provided in an embodiment of the present application is shown;

[0018] Figure 2 A schematic diagram of a flow chart of a fault isolation method for a power distribution system provided according to an embodiment of the present application is shown;

[0019] Figure 3 A schematic diagram of a MACP-CHB-ESS post-fault locking protection scheme provided according to an embodiment of the present application is shown;

[0020] Figure 4 A schematic diagram showing a current path when a short circuit fault occurs in a second power supply line provided in an embodiment of the present application is shown;

[0021] Figure 5 A schematic diagram of an equivalent circuit of a three-power supply line interconnection system after submodule locking and bypassing provided in an embodiment of the present application is shown;

[0022] Figure 6 A schematic diagram showing a three-phase short circuit fault occurring in a second power supply line according to an embodiment of the present application is shown;

[0023] Figure 7 A schematic diagram showing an equivalent circuit when a three-phase short circuit fault occurs in a second power supply line provided in an embodiment of the present application is shown;

[0024] Figure 8 A schematic diagram of a composite sequence network when a two-phase short circuit occurs in a second power supply line provided in an embodiment of the present application is shown;

[0025] Fig. 9 A schematic diagram of a composite sequence network when a BC two-phase short circuit to ground occurs in a second power supply line provided in an embodiment of the present application is shown;

[0026] Fig.10 A schematic diagram of a composite sequence network when a phase A short circuit and grounding occurs in a second power supply line provided in an embodiment of the present application is shown;

[0027] Fig.11 A flow chart of a MACP-CHB-ESS device fault diagnosis and line selection method provided according to an embodiment of the present application is shown;

[0028] Fig.12 A schematic diagram showing a current waveform of a MACP-CHB-ESS power supply line 1 when a two-phase short circuit fault occurs in a second power supply line provided according to an embodiment of the present application is shown;

[0029] Fig.13 A schematic diagram showing a current waveform of a second power supply line of a MACP-CHB-ESS when a two-phase short circuit fault occurs in a power supply line 3 provided in an embodiment of the present application is shown;

[0030] Fig.14 A schematic diagram showing a current waveform of a MACP-CHB-ESS power supply line 3 when a two-phase short circuit fault occurs in a second power supply line provided according to an embodiment of the present application is shown;

[0031] Fig.15 A structural block diagram of a fault isolation device for a power distribution system provided according to an embodiment of the present application is shown.

[0032] The above drawings include the following reference numerals:

[0033] 102, processor; 104, memory; 106, transmission device; 108, input and output devices. DETAILED DESCRIPTION

[0034] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0036] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0037] As introduced in the background technology, in the prior art, MACP-CHB-ESS realizes the interconnection of multiple medium-voltage AC ports with the same large-capacity energy storage system. Due to the power interaction between multiple ports, when a power supply line fails, the voltage and current distribution characteristics in the fault state are more complicated. Short-circuit faults can cause a series of hazards such as burning of power electronic components, damage to energy storage units, voltage drops or fluctuations, and local fault expansion, which have a profound impact on the stability and safety of the entire power system. In order to solve the problem in the prior art that when a short-circuit fault occurs in shared energy storage flexible interconnection equipment, the fault current will increase rapidly, causing damage to the energy storage unit, and the fault is easy to spread, the embodiments of the present application provide a fault isolation method for a distribution system, a fault isolation device for a distribution system, a computer-readable storage medium, and an electronic device.

[0038] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0039] The method embodiments provided in the embodiments of the present application can be executed in a mobile terminal, a computer terminal or a similar computing device. Taking running on a mobile terminal as an example, Figure 1 FIG. 1 is a hardware structure block diagram of a mobile terminal of a method for isolating a fault in a power distribution system according to an embodiment of the present invention. Figure 1 As shown, the mobile terminal may include one or more ( Figure 1Only one is shown in the figure) a processor 102 (the processor 102 may include but is not limited to a processing device such as a microprocessor MCU or a programmable logic device FPGA) and a memory 104 for storing data, wherein the mobile terminal may also include a transmission device 106 and an input / output device 108 for communication functions. It can be understood by those skilled in the art that Figure 1 The structure shown is for illustration only and does not limit the structure of the mobile terminal. Figure 1 More or fewer components as shown, or with Figure 1 Different configurations are shown.

[0040] The memory 104 can be used to store computer programs, for example, software programs and modules of application software, such as the computer program corresponding to the Z method in the embodiment of the present invention. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, that is, the above method is implemented. The memory 104 may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 104 may further include a memory remotely arranged relative to the processor 102, and these remote memories may be connected to the mobile terminal via a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof. The transmission device 106 is used to receive or send data via a network. The above-mentioned specific examples of the network may include a wireless network provided by a communication provider of the mobile terminal. In one example, the transmission device 106 includes a network adapter (Network Interface Controller, referred to as NIC), which can be connected to other network devices through a base station so as to communicate with the Internet. In one example, the transmission device 106 may be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0041] In this embodiment, a Z method running on a mobile terminal, a computer terminal or a similar computing device is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0042] Figure 2 FIG. 1 is a flow chart of a method for isolating a fault in a power distribution system according to an embodiment of the present application. Figure 2 As shown, the method comprises the following steps:

[0043] Step S201, in the case where the power distribution system includes a plurality of the power supply lines, obtaining power flow parameters of each of the power supply lines in the power distribution system, wherein the power flow parameters at least include a collected current and a collected voltage;

[0044] In an optional solution, a corresponding half-bridge current control module is connected between the port inductor of the power supply line and the DC bus, and the half-bridge current control module includes a first power module on the first bridge wall and a second power module on the second bridge wall, and the second power module is connected in parallel with the thyristor bypass switch.

[0045] Specifically, sensors installed at each power supply line node of the energy storage system are used to monitor and collect current, voltage and other power flow parameters in real time, providing basic data for subsequent fault diagnosis and processing of the distribution system.

[0046] Step S202, when the power flow parameter of at least one of the power supply lines is not within the corresponding threshold range, determining that a fault occurs in the power distribution system;

[0047] Specifically, judging whether there is any abnormality in the multi-terminal shared energy storage system based on the power flow parameters transmitted by the sensor can identify faults in a timely manner, which is a safe and reliable guarantee for fault diagnosis and positioning.

[0048] In one alternative, Figure 3 As shown, taking phase A and three power supply ports as an example, a mechanical circuit breaker is installed between the port inductor and the common connection point (PCC) in each power supply line, and in the half-bridge power flow control module (PFCM), the lower IGBT module is installed with a thyristor bypass switch (TBS), and the above power flow control modules are connected in parallel to the common DC bus, and a DC unloading circuit is connected in parallel to the DC bus. In the connected chain energy storage system, a fast mechanical switch is connected between the midpoints of the two bridge arms of each energy storage power unit, and a DC unloading circuit is connected in parallel to the DC side of the energy storage battery.

[0049] Furthermore, when the protection does not operate, the fault current path of the three-power supply line source-grid-load-storage flexible interconnected distribution system is as follows: Figure 4 As shown by Figure 4 It can be seen that due to the power interaction between multiple ports, fault transmission will occur, and short-circuit current will flow through the three power supply lines, causing the voltage at the normal port to drop, which is not conducive to the operation of the system.

[0050] After the relay protection is started, since the sum of the DC voltages of each phase of the CHB-ESS is greater than the phase voltage amplitude at the grid connection point, the diode is subjected to a reverse voltage drop and is turned off, and the parallel current is zero. At this time, the fault current path is the current-limiting inductance of each port of the multi-terminal energy storage system. The influence of CHB-ESS and PFCM can be ignored when performing transient analysis on the device after the disturbance. Figure 5The equivalent circuit of the multi-power supply line energy storage sharing system is shown.

[0051] Wherein, when the power flow parameter of at least one of the power supply lines is not within the corresponding threshold range, determining that the power distribution system fails comprises the following steps:

[0052] Step S2021, when the collected current of the power supply line is greater than the first protection setting value, and the zero-sequence current component of the power supply line is greater than the second protection setting value, it is determined that a short circuit fault occurs in the power distribution system, and all power devices in the half-bridge power flow control module are controlled to be locked, and after the dead time, the thyristor bypass switch is turned on;

[0053] Step S2022, when the collected current of the power supply line is greater than the first protection setting value, and the zero-sequence current component of the power supply line is less than the second protection setting value, it is determined that a phase-to-phase short circuit fault occurs in the power distribution system;

[0054] Step S2023, when the zero-sequence current component of the above-mentioned power supply line is greater than the current reference value, it is determined that the above-mentioned distribution system has a ground short circuit fault, and the above-mentioned current reference value is less than the above-mentioned first protection setting value and the above-mentioned second protection setting value.

[0055] Specifically, by detecting the initial short-circuit fault signal evaluation and establishing the detection threshold, the fault type can be determined quickly and accurately, facilitating the subsequent coordination with the system circuit breaker to isolate the fault, avoid the fault from expanding the impact range, and interfere with the normal power supply line, thus ensuring the safety and reliability of the power grid.

[0056] Step S203, in the event of a short circuit fault in the power distribution system, determining the power supply line with the largest collected current as a fault line;

[0057] Specifically, in a multi-port source-grid-load-storage flexible interconnected distribution system, due to the power coupling between the ports, when a short circuit occurs in a power supply line, the fault may spread through the power path of the system, causing the current of other normal power supply lines to increase. However, under various fault conditions, two normal power supply lines usually simultaneously flow fault current into the fault line, so the current amplitude in the normal line is much smaller than the fault current in the fault line. Rapidly locating the faulty power supply line and isolating the fault with the system circuit breaker can effectively protect the distribution system and switchgear from damage, improve the transient stability of the system, and facilitate power supply restoration and operation after the device fault is isolated.

[0058] In one optional solution, a transient analysis is performed on a neutral point low resistance grounded distribution system to identify possible fault types and locations. For various asymmetric short circuit faults such as single-phase short circuit, they are analyzed by the symmetrical component method, where a short circuit fault in the second power supply line is taken as an example.

[0059] The power supply line includes a first power supply line, a second power supply line and a third power supply line. When a short circuit occurs in the power distribution system, before determining the power supply line with the largest collected current as the faulty line, the method further includes the following steps:

[0060] Step S301: when a three-phase short circuit occurs in the second power supply line at a historical moment, according to the first current formula and the second current formula , respectively determine the three-phase current of the first power supply line and the three-phase current of the third power supply line, wherein, is the three-phase current of the first power supply line, is the three-phase current of the third power supply line, is the equivalent electromotive force of the first power supply line, is the equivalent electromotive force of the third power supply line, is the equivalent transformer impedance of the first power supply line, is the equivalent transformer impedance of the third power supply line, is the equivalent inductance of the first power supply line, is the equivalent inductance of the third power supply line, ω is the angular frequency, and Lc represents the filter inductance of the power supply line;

[0061] Step S302: According to the KCL law, determine that the three-phase short-circuit current of the second power supply line is the sum of the three-phase current of the first power supply line and the three-phase current of the third power supply line.

[0062] Specifically, Figure 6 and Figure 7 The schematic diagrams of the three-phase short circuit fault in the second power supply line and the simplified equivalent circuit are given respectively. According to the KCL law, the phase current flowing through the PCC point of the faulty power supply line is , from the above formula, we can know that the three-phase short-circuit current of the faulty power supply line is the sum of the currents of the two normal power supply lines, which is obviously larger than the two normal power supply lines. Therefore, the situation of the three-phase short-circuit fault can be judged more accurately.

[0063] The power distribution system includes a first power supply line, a second power supply line and a third power supply line. When a short circuit occurs in the power distribution system, before determining the power supply line with the largest collected current as the faulty line, the method further includes the following steps:

[0064] Step S401: when a two-phase short circuit occurs in the second power supply line at a historical moment, according to the first A-phase current positive sequence component formula The positive and negative zero-sequence phase rotation relationship of the ABC three-phase , determine the two-phase short-circuit current of the second power supply line, the two-phase short-circuit fault is a B-phase short-circuit fault and a C-phase short-circuit fault, wherein, is the positive sequence component of phase A current, is the phase A current, is the negative sequence component of phase A current, is the zero-sequence component of phase A current, is the B phase current, is the C phase current, is the rotation factor, is the positive sequence equivalent reactance of non-fault phase A, is the negative sequence equivalent reactance of non-fault phase A;

[0065] Step S402, based on the KCL law, determine that the B-phase short-circuit current of the above-mentioned second power supply line is the sum of the B-phase current of the above-mentioned first power supply line and the B-phase current of the above-mentioned third power supply line, and the C-phase short-circuit current of the above-mentioned second power supply line is the sum of the C-phase current of the above-mentioned first power supply line and the C-phase current of the above-mentioned third power supply line.

[0066] Specifically, we first analyze the two-phase short circuit fault. Taking the BC two-phase short circuit fault in the second power supply line as an example, the boundary condition of the phase component at the short circuit point is It can be seen that only the fault phase has fault current at the fault point, and the fault current of the normal phase is 0. The above formula uses sequence components to express the boundary conditions as follows: , thus obtaining the composite sequence network when BC two-phase short circuit is as follows Figure 8 shown.

[0067] Furthermore, according to the KCL law, the current distribution relationship of the three power supply lines is For the fault BC two-phase fault current, since the two normal power supply lines simultaneously flow fault current into the fault power supply line, its current transient characteristics are also that the fault power supply line is greater than the two normal power supply lines. This can accurately determine the situation of a two-phase short circuit fault.

[0068] The power distribution system includes a first power supply line, a second power supply line and a third power supply line. When a short circuit occurs in the power distribution system, before determining the power supply line with the largest collected current as the faulty line, the method further includes the following steps:

[0069] Step S501: when a two-phase ground short circuit fault occurs in the second power supply line at a historical moment, according to the second A phase current positive sequence component formula The two-phase short-circuit current of the second power supply line is determined by the positive and negative zero-sequence phase rotation relationship of the three phases ABC. The two-phase grounding short-circuit fault is a B-phase grounding short-circuit fault and a C-phase grounding short-circuit fault, wherein: is the positive sequence current of non-fault phase A, is the equivalent electromotive force of non-fault phase A, is the positive sequence equivalent reactance of non-fault phase A, is the negative sequence equivalent reactance of non-fault phase A, is the zero-sequence equivalent reactance of non-fault phase A, is the transition resistance;

[0070] Step S502, based on the KCL law, determine that the B-phase short-circuit current of the above-mentioned second power supply line is the sum of the B-phase current of the above-mentioned first power supply line and the B-phase current of the above-mentioned third power supply line, and the C-phase short-circuit current of the above-mentioned second power supply line is the sum of the C-phase current of the above-mentioned first power supply line and the C-phase current of the above-mentioned third power supply line.

[0071] Specifically, taking the BC two-phase short circuit grounding fault of the second power supply line as an example, the boundary condition of the short-circuit point phase component is It can be seen that only the faulty phases BC have fault current at the fault point, and the normal phase A fault current is 0. The boundary condition expressed by the sequence component in the above formula is , so we can get the composite sequence network when BC two-phase short circuit grounding is as follows Fig. 9 shown.

[0072] Furthermore, according to the KCL law, the current distribution relationship of the three power supply lines is: For the fault BC two-phase fault current, since the two normal power supply lines simultaneously flow the fault current into the fault power supply line, its transient current is also greater than the two normal power supply lines, and there is a zero-sequence component. This can accurately determine the situation of a two-phase ground short circuit fault.

[0073] The power distribution system includes a first power supply line, a second power supply line and a third power supply line. When a short circuit occurs in the power distribution system, before determining the power supply line with the largest collected current as the faulty line, the method further includes the following steps:

[0074] Step S601, when a single-phase short circuit fault occurs in the second power supply line at a historical moment, obtaining a short-circuit current of the A phase at the short-circuit point on the second power supply line;

[0075] Wherein, obtaining the A-phase short-circuit current of the short-circuit point on the second power supply line includes: based on the A-phase short-circuit formula , determine the A-phase short-circuit current of the short-circuit point on the second power supply line, where: is the positive sequence current of non-fault phase A, is the negative sequence current of non-fault phase A, is the zero-sequence current of non-fault phase A, is the equivalent electromotive force of non-fault phase A, is the positive sequence equivalent reactance of non-fault phase A, is the negative sequence equivalent reactance of non-fault phase A, is the zero-sequence equivalent reactance of non-fault phase A, is the transition resistor.

[0076] Step S602: According to the A-phase short-circuit current and single-phase current formula of the short-circuit point on the second power supply line, , determine the single-phase short-circuit current of the second power supply line, wherein, is the positive sequence component of phase A current, is the phase A current, is the negative sequence component of phase A current, is the zero-sequence component of phase A current;

[0077] Step S603: Based on the KCL law, determine that the single-phase short-circuit current of the second power supply line is the sum of the single-phase current of the first power supply line and the single-phase current of the third power supply line.

[0078] Specifically, taking the A-phase short circuit grounding fault of the second power supply line as an example, the boundary condition of the short-circuit point phase component is It can be seen that only the fault phase has fault current at the fault point, and the fault current of the normal phase is 0. The above formula uses sequence components to express the boundary conditions as follows: , so we can get the composite sequence network when phase A is short-circuited to ground as follows Fig.10 shown.

[0079] Furthermore, the two-phase short-circuit current at the fault point BC is 0, and according to the KCL law, the fault current distribution relationship of phase A of the three power supply lines is For the A-phase fault current, since the two normal power supply lines simultaneously flow the fault current into the fault power supply line, its current characteristic is also that the fault power supply line is greater than the two normal power supply lines. Its characteristic relative to the phase-to-phase short circuit is that the transient current has a zero-sequence component. This can accurately determine the situation of a single-phase short circuit grounding fault.

[0080] Specifically, when the system encounters a ground short circuit fault, the fault current may be small, which may make the protection device unable to accurately identify whether a fault has occurred, resulting in refusal to operate or no operation. However, given that multi-port shared energy storage chain energy storage systems are usually used in urban distribution networks with a low resistance grounded at the neutral point, ground faults will cause the generation of zero-sequence current components. Through transient analysis, the change in the zero-sequence current component can be used to identify ground faults. When it is detected that the zero-sequence current exceeds the preset setting value, it can be confirmed that a ground fault has occurred in the system.

[0081] Step S204: sending a trip signal to the circuit breaker of the fault line to control the circuit breaker of the fault line to trip instantly, so as to cut off the connection between the fault line and the power distribution system and complete fault isolation.

[0082] Specifically, Fig.11 The specific process of fault diagnosis and line selection of MACP-CHB-ESS device is given. Firstly, fault detection is carried out. If a fault is judged to occur, the IGBT is locked and the TBS is turned on. The collected current and the reference current value are compared and divided into phase fault and ground fault. Then, the faulty power supply line is located and isolated according to the three current values. After the fault isolation is completed, the operation control is restored.

[0083] Furthermore, power electronic switches are significantly less tolerant to abnormal voltages and currents than traditional primary devices (such as transformers and sectionalizers), and are therefore more susceptible to overvoltage and overcurrent. To prevent fault currents from damaging these sensitive power components, the cascaded H-bridge energy storage system (CHB-ESS) and the power flow regulation module in parallel must be quickly isolated when a fault occurs, and the PFCM must be bypassed at the same time. This fast protection mechanism can effectively prevent fault currents from entering critical equipment, thereby ensuring the safety and stable operation of the system.

[0084] The present application provides a specific implementation case, analyzing the situation where a BC two-phase short circuit fault occurs in the second power supply line of MACP-CHB-ESS, wherein the fault sequence is set as follows: the fault occurs at t=0.1s, the current overcurrent protection plus the TBS conduction time is set to 1.5ms, and after 50ms, according to the fault diagnosis and positioning method provided in the present application, the faulty power supply line is determined by comparing the power supply line current. At t=0.15s, MACP-CHB-ESS sends a trip command to the power supply line outlet circuit breaker that has been determined to be the faulty line, thereby completing fault isolation.

[0085] Fig.12 , Fig.13 and Fig.14The simulation results of the above implementation case using MATLAB / Simulink software to simulate and verify the system are given. The results show that when a short circuit fault occurs in the AC power supply line, the current characteristics of the three power supply lines are highly consistent with the theoretical analysis results. The fault diagnosis and location method proposed in the present invention can accurately identify the fault line and quickly cut off the connection between the equipment and the fault line, thereby effectively reducing the impact of the fault current on the MACP-CHB-ESS system. After the fault line trips, the current of the remaining normal power supply lines quickly returns to a safe range, which helps the system to quickly restore power supply after fault isolation.

[0086] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0087] The embodiment of the present application also provides a fault isolation device for a power distribution system. It should be noted that the fault isolation device for a power distribution system in the embodiment of the present application can be used to execute the fault isolation method for a power distribution system provided in the embodiment of the present application. The device is used to implement the above-mentioned embodiments and preferred implementation modes, and the descriptions that have been made will not be repeated. As used below, the term "module" can implement a combination of software and / or hardware for a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

[0088] The following is an introduction to the fault isolation device of the power distribution system provided in the embodiment of the present application.

[0089] Fig.15 Schematic diagram of a fault isolation device for a power distribution system according to an embodiment of the present application. Fig.15As shown, the power distribution system is a topological structure based on a multi-port chain battery energy storage system, the power distribution system includes at least one power supply line, and a circuit breaker is installed between the port inductance of each of the power supply lines and the common connection point. The device includes: an acquisition unit 10, a first determination unit 20, a second determination unit 30 and a fault isolation unit 40, the acquisition unit 10 is used to acquire the flow parameters of each of the power supply lines in the power distribution system when the power distribution system includes multiple power supply lines, and the flow parameters at least include the acquisition current and the acquisition voltage; the first determination unit 20 is used to determine that the power distribution system has a fault when the flow parameters of at least one of the power supply lines are not within the corresponding threshold range; the second determination unit 30 is used to determine that the power supply line with the largest acquisition current is a fault line when a short circuit fault occurs in the power distribution system; the fault isolation unit 40 is used to send a trip signal to the circuit breaker of the fault line to control the circuit breaker of the fault line to trip instantly, so as to cut off the connection between the fault line and the power distribution system, and complete the fault isolation.

[0090] The fault isolation device of the above-mentioned distribution system of the present application includes an acquisition unit, a first determination unit, a second determination unit and a fault isolation unit. The acquisition unit is used to acquire the flow parameters of each of the above-mentioned power supply lines in the above-mentioned distribution system when the above-mentioned distribution system includes multiple above-mentioned power supply lines, and the above-mentioned flow parameters at least include a collection current and a collection voltage; the first determination unit is used to determine that the above-mentioned distribution system has a fault when the flow parameters of at least one of the above-mentioned power supply lines are not within the corresponding threshold range; the second determination unit is used to determine that the above-mentioned power supply line with the largest collection current is a fault line when a short-circuit fault occurs in the above-mentioned distribution system; the fault isolation unit is used to send a tripping signal to the circuit breaker of the above-mentioned fault line to control the circuit breaker of the above-mentioned fault line to trip instantly, so as to cut off the connection between the above-mentioned fault line and the above-mentioned distribution system, and complete fault isolation. The device can accurately determine the fault of the shared energy storage power supply line, disconnect the system from the faulty power supply line, avoid the transmission of faults between multiple power supply lines when a large disturbance occurs, affect other normal power supply lines, and reduce the impact of the disturbance on the system. At the same time, the device can safely transition under fault conditions, preventing the device from being in a faulty state for a long time when the AC power supply line area protection fails to operate, causing damage to the device. Rapid disconnection of the device from the faulty power supply line is conducive to achieving power supply recovery and flow control after the fault, thereby improving the system power supply reliability.

[0091] In some examples, the first determination unit includes a first determination module, a second determination module and a third determination module. The first determination module is used to determine that a short circuit fault occurs in the distribution system when the collected current of the power supply line is greater than the first protection setting value and the zero-sequence current component of the power supply line is greater than the second protection setting value, and control all power devices in the half-bridge power flow control module to lock, and turn on the thyristor bypass switch after the dead time; the second determination module is used to determine that a phase-to-phase short circuit fault occurs in the distribution system when the collected current of the power supply line is greater than the first protection setting value and the zero-sequence current component of the power supply line is less than the second protection setting value; the third determination module is used to determine that a ground short circuit fault occurs in the distribution system when the zero-sequence current component of the power supply line is greater than the current reference value, and the current reference value is less than the first protection setting value and the second protection setting value. Detecting the initial short-circuit fault signal evaluation and establishing the detection threshold can quickly and accurately determine the fault type, facilitate the subsequent coordination of the system circuit breaker to isolate the fault, avoid the fault expansion impact range, interfere with the normal power supply line, and ensure the safety and reliability of the power grid.

[0092] In some examples, the second determining unit includes a fourth determining module and a fifth determining module, the fourth determining module being used to determine the current of the second power supply line according to the first current formula when a three-phase short circuit fault occurs in the second power supply line at a historical moment. and the second current formula , respectively determine the three-phase current of the first power supply line and the three-phase current of the third power supply line, wherein, is the three-phase current of the first power supply line, is the three-phase current of the third power supply line, is the equivalent electromotive force of the first power supply line, is the equivalent electromotive force of the third power supply line, is the equivalent transformer impedance of the first power supply line, is the equivalent transformer impedance of the third power supply line, is the equivalent inductance of the first power supply line, The equivalent inductance ω of the third power supply line is the angular frequency, and Lc represents the filter inductance of the power supply line; the fifth determination module is used to determine, according to the KCL law, that the three-phase short-circuit current of the second power supply line is the sum of the three-phase current of the first power supply line and the three-phase current of the third power supply line. In this way, the situation of the three-phase short-circuit fault can be accurately determined.

[0093] In some examples, the second determination unit further includes a sixth determination module and a seventh determination module, the sixth determination module being used to determine the positive sequence component of the first phase A current according to the formula when a two-phase short circuit fault occurs in the second power supply line at a historical moment. The positive and negative zero-sequence phase rotation relationship of the ABC three-phase , determine the two-phase short-circuit current of the second power supply line, the two-phase short-circuit fault is a B-phase short-circuit fault and a C-phase short-circuit fault, wherein, is the positive sequence component of phase A current, is the phase A current, is the negative sequence component of phase A current, is the zero-sequence component of phase A current, is the B phase current, is the C phase current, is the rotation factor, is the positive sequence equivalent reactance of non-fault phase A, is the negative sequence equivalent reactance of the non-faulty A phase; the seventh determination module is used to determine, based on the KCL law, that the B-phase short-circuit current of the second power supply line is the sum of the B-phase current of the first power supply line and the B-phase current of the third power supply line, and that the C-phase short-circuit current of the second power supply line is the sum of the C-phase current of the first power supply line and the C-phase current of the third power supply line. In this way, the situation of a two-phase short-circuit fault can be accurately determined.

[0094] In some examples, the second determination unit further includes an eighth determination module and a ninth determination module, wherein the eighth determination module is used to determine the positive sequence component of the second A phase current according to the formula when a two-phase ground short circuit fault occurs in the second power supply line at a historical moment. The two-phase short-circuit current of the second power supply line is determined by the positive and negative zero-sequence phase rotation relationship of the three phases ABC. The two-phase grounding short-circuit fault is a B-phase grounding short-circuit fault and a C-phase grounding short-circuit fault, wherein: is the positive sequence current of non-fault phase A, is the equivalent electromotive force of non-fault phase A, is the positive sequence equivalent reactance of non-fault phase A, is the negative sequence equivalent reactance of non-fault phase A, is the zero-sequence equivalent reactance of non-fault phase A, The ninth determination module is used to determine, based on the KCL law, that the B-phase short-circuit current of the second power supply line is the sum of the B-phase current of the first power supply line and the B-phase current of the third power supply line, and the C-phase short-circuit current of the second power supply line is the sum of the C-phase current of the first power supply line and the C-phase current of the third power supply line. In this way, the situation of a two-phase ground short-circuit fault can be accurately determined.

[0095] In some examples, the second determination unit further includes a tenth determination module, an eleventh determination module and a twelfth determination module, the tenth determination module is used to obtain the A-phase short-circuit current of the short-circuit point on the second power supply line when a single-phase short-circuit fault occurs in the second power supply line at a historical moment; the eleventh determination module is used to determine the A-phase short-circuit current of the short-circuit point on the second power supply line according to the A-phase short-circuit current and the single-phase current formula , determine the single-phase short-circuit current of the second power supply line, wherein, is the positive sequence component of phase A current, is the phase A current, is the negative sequence component of phase A current, The twelfth determination module is used to determine, based on the KCL law, that the single-phase short-circuit current of the second power supply line is the sum of the single-phase current of the first power supply line and the single-phase current of the third power supply line. In this way, the single-phase short-circuit grounding fault can be accurately determined.

[0096] In some examples, the tenth determination module includes a first determination submodule for determining the phase A short circuit formula based on the phase A short circuit formula , determine the A-phase short-circuit current of the short-circuit point on the second power supply line, where: is the positive sequence current of non-fault phase A, is the negative sequence current of non-fault phase A, is the zero-sequence current of non-fault phase A, is the equivalent electromotive force of non-fault phase A, is the positive sequence equivalent reactance of non-fault phase A, is the negative sequence equivalent reactance of non-fault phase A, is the zero-sequence equivalent reactance of non-fault phase A, is the transition resistance. Thus, the short circuit and grounding fault of phase A can be accurately determined.

[0097] The fault isolation device of the power distribution system includes a processor and a memory. The acquisition unit and the like are stored in the memory as program units, and the processor executes the program units stored in the memory to implement corresponding functions. The modules are all located in the same processor; or, the modules are located in different processors in any combination.

[0098] The processor includes a kernel, which retrieves the corresponding program unit from the memory. One or more kernels can be set, and the kernel parameters can be adjusted to solve the problem in the prior art that when a short circuit fault occurs in the shared energy storage flexible interconnection equipment, the fault current will increase rapidly, causing damage to the energy storage unit, and the fault is easy to spread.

[0099] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0100] An embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium includes a stored program, wherein when the program is executed, the device where the computer-readable storage medium is located is controlled to execute the fault isolation method of the power distribution system.

[0101] Specifically, the fault isolation method of the power distribution system includes:

[0102] Step S201, in the case where the power distribution system includes a plurality of the power supply lines, obtaining power flow parameters of each of the power supply lines in the power distribution system, wherein the power flow parameters at least include a collected current and a collected voltage;

[0103] Step S202, when the power flow parameter of at least one of the power supply lines is not within the corresponding threshold range, determining that a fault occurs in the power distribution system;

[0104] Step S203, in the event of a short circuit fault in the power distribution system, determining the power supply line with the largest collected current as a fault line;

[0105] Step S204: sending a trip signal to the circuit breaker of the fault line to control the circuit breaker of the fault line to trip instantly, so as to cut off the connection between the fault line and the power distribution system and complete fault isolation.

[0106] Optionally, a corresponding half-bridge power flow control module is connected between the port inductor of the power supply line and the DC bus, the half-bridge power flow control module includes a first power module on the first bridge wall and a second power module on the second bridge wall, the second power module is connected in parallel with the thyristor bypass switch, and when the power flow parameter of at least one of the power supply lines is not within the corresponding threshold range, determining that the power distribution system has a fault includes: when the collected current of the power supply line is greater than the first protection setting value, and the zero-sequence current component of the power supply line is greater than the second protection setting value, determining that the above A short circuit fault occurs in the distribution system, and all power devices in the above-mentioned half-bridge power flow control module are controlled to be locked, and the above-mentioned thyristor bypass switch is turned on after the dead time; when the collected current of the above-mentioned power supply line is greater than the above-mentioned first protection setting value, and the zero-sequence current component of the above-mentioned power supply line is less than the above-mentioned second protection setting value, it is determined that the above-mentioned distribution system has a phase-to-phase short circuit fault; when the zero-sequence current component of the above-mentioned power supply line is greater than the current reference value, it is determined that the above-mentioned distribution system has a ground short circuit fault, and the above-mentioned current reference value is less than the above-mentioned first protection setting value and the above-mentioned second protection setting value.

[0107] Optionally, the power supply line includes a first power supply line, a second power supply line and a third power supply line. When a short circuit fault occurs in the power distribution system, before determining the power supply line with the largest collected current as the faulty line, the method further includes: when a three-phase short circuit fault occurs in the second power supply line at a historical moment, according to the first current formula and the second current formula , respectively determine the three-phase current of the first power supply line and the three-phase current of the third power supply line, wherein, is the three-phase current of the first power supply line, is the three-phase current of the third power supply line, is the equivalent electromotive force of the first power supply line, is the equivalent electromotive force of the third power supply line, is the equivalent transformer impedance of the first power supply line, is the equivalent transformer impedance of the third power supply line, is the equivalent inductance of the first power supply line, The equivalent inductance ω of the third power supply line is the angular frequency, and Lc represents the filter inductance of the power supply line. According to the KCL law, the three-phase short-circuit current of the second power supply line is determined to be the sum of the three-phase current of the first power supply line and the three-phase current of the third power supply line.

[0108] Optionally, the power distribution system includes a first power supply line, a second power supply line and a third power supply line. When a short circuit fault occurs in the power distribution system, before determining the power supply line with the largest collected current as the faulty line, the method further includes: when a two-phase short circuit fault occurs in the second power supply line at a historical moment, according to the first A-phase current positive sequence component formula The positive and negative zero-sequence phase rotation relationship of the ABC three-phase , determine the two-phase short-circuit current of the second power supply line, the two-phase short-circuit fault is a B-phase short-circuit fault and a C-phase short-circuit fault, wherein, is the positive sequence component of phase A current, is the phase A current, is the negative sequence component of phase A current, is the zero-sequence component of phase A current, is the B phase current, is the C phase current, is the rotation factor, is the positive sequence equivalent reactance of non-fault phase A, is the negative-sequence equivalent reactance of the non-fault phase A; based on the KCL law, it is determined that the B-phase short-circuit current of the second power supply line is the sum of the B-phase current of the first power supply line and the B-phase current of the third power supply line, and the C-phase short-circuit current of the second power supply line is the sum of the C-phase current of the first power supply line and the C-phase current of the third power supply line.

[0109] Optionally, the power distribution system includes a first power supply line, a second power supply line and a third power supply line. When a short circuit fault occurs in the power distribution system, before determining the power supply line with the largest collected current as the faulty line, the method further includes: when a two-phase ground short circuit fault occurs in the second power supply line at a historical moment, according to the second A phase current positive sequence component formula The two-phase short-circuit current of the second power supply line is determined by the positive and negative zero-sequence phase rotation relationship of the three phases ABC. The two-phase grounding short-circuit fault is a B-phase grounding short-circuit fault and a C-phase grounding short-circuit fault, wherein: is the positive sequence current of non-fault phase A, is the equivalent electromotive force of non-fault phase A, is the positive sequence equivalent reactance of non-fault phase A, is the negative sequence equivalent reactance of non-fault phase A, is the zero-sequence equivalent reactance of non-fault phase A, is the transition resistance; based on the KCL law, it is determined that the B-phase short-circuit current of the second power supply line is the sum of the B-phase current of the first power supply line and the B-phase current of the third power supply line, and the C-phase short-circuit current of the second power supply line is the sum of the C-phase current of the first power supply line and the C-phase current of the third power supply line.

[0110] Optionally, the power distribution system includes a first power supply line, a second power supply line and a third power supply line. When a short-circuit fault occurs in the power distribution system, before determining the power supply line with the largest collected current as the faulty line, the method further includes: when a single-phase short-circuit fault occurs in the second power supply line at a historical moment, obtaining the A-phase short-circuit current of the short-circuit point on the second power supply line; and obtaining the A-phase short-circuit current of the short-circuit point on the second power supply line according to the A-phase short-circuit current and the single-phase current formula. , determine the single-phase short-circuit current of the second power supply line, wherein, is the positive sequence component of phase A current, is the phase A current, is the negative sequence component of phase A current, is the zero-sequence component of the phase A current; based on the KCL law, it is determined that the single-phase short-circuit current of the second power supply line is the sum of the single-phase current of the first power supply line and the single-phase current of the third power supply line.

[0111] Optionally, obtaining the A-phase short-circuit current of the short-circuit point on the second power supply line includes: based on the A-phase short-circuit formula , determine the A-phase short-circuit current of the short-circuit point on the second power supply line, where: is the positive sequence current of non-fault phase A, is the negative sequence current of non-fault phase A, is the zero-sequence current of non-fault phase A, is the equivalent electromotive force of non-fault phase A, is the positive sequence equivalent reactance of non-fault phase A, is the negative sequence equivalent reactance of non-fault phase A, is the zero-sequence equivalent reactance of non-fault phase A, is the transition resistor.

[0112] An embodiment of the present invention provides a processor, and the processor is used to run a program, wherein the fault isolation method of the power distribution system is executed when the program is run.

[0113] An embodiment of the present invention provides a device, which includes a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, at least the steps of the above method are implemented.

[0114] The devices in this article can be servers, PCs, PADs, mobile phones, etc.

[0115] The present application also provides a computer program product, which, when executed on a data processing device, is suitable for executing a program that initializes at least the steps of the above method.

[0116] Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, and in some cases, the steps shown or described can be executed in a different order than here, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present invention is not limited to any specific combination of hardware and software.

[0117] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0118] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0119] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0120] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0121] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0122] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0123] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0124] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0125] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0126] 1) The fault isolation method of the above-mentioned power distribution system of the present application, first, when the power distribution system includes multiple power supply lines, the power flow parameters of each power supply line in the power distribution system are obtained, and the power flow parameters at least include the collected current and the collected voltage; when the power flow parameters of at least one power supply line are not within the corresponding threshold range, it is determined that the power distribution system has a fault; when a short circuit fault occurs in the power distribution system, the power supply line with the largest collected current is determined as the fault line; a trip signal is sent to the circuit breaker of the fault line to control the instantaneous tripping of the circuit breaker of the fault line to cut off the connection between the fault line and the power distribution system to complete the fault isolation. This method can accurately determine the fault of the shared energy storage power supply line, disconnect the system from the fault power supply line, avoid the transmission of faults between multiple power supply lines when a large disturbance occurs, affect other normal power supply lines, and reduce the impact of disturbances on the system. At the same time, this method can also ensure the safe transition of the device in the fault state, prevent the device from being in a fault state for a long time when the AC power supply line area protection refuses to operate, and cause damage to the device, and quickly cut off the connection between the device and the faulty power supply line is conducive to realizing power supply recovery and power flow regulation after the fault, and improves the power supply reliability of the system.

[0127] 2) The fault isolation device of the above-mentioned power distribution system of the present application comprises an acquisition unit, a first determination unit, a second determination unit and a fault isolation unit. The acquisition unit is used to acquire the flow parameters of each of the above-mentioned power supply lines in the above-mentioned power distribution system when the above-mentioned power distribution system includes multiple above-mentioned power supply lines, and the above-mentioned flow parameters at least include a collection current and a collection voltage; the first determination unit is used to determine that the above-mentioned power distribution system has a fault when the flow parameters of at least one of the above-mentioned power supply lines are not within the corresponding threshold range; the second determination unit is used to determine that the above-mentioned power distribution system has a fault when a short-circuit fault occurs in the above-mentioned power distribution system, and the power supply line with the largest collection current is determined as a fault line; the fault isolation unit is used to send a trip signal to the circuit breaker of the above-mentioned fault line to control the circuit breaker of the above-mentioned fault line to trip instantly, so as to cut off the connection between the above-mentioned fault line and the above-mentioned power distribution system, and complete fault isolation. The device can accurately determine the fault of the shared energy storage power supply line, disconnect the system from the faulty power supply line, avoid the transmission of faults between multiple power supply lines when a large disturbance occurs, affect other normal power supply lines, and reduce the impact of the disturbance on the system. At the same time, the device can safely transition under fault conditions, preventing the device from being in a faulty state for a long time when the AC power supply line area protection fails to operate, causing damage to the device. Rapid disconnection of the device from the faulty power supply line is conducive to achieving power supply recovery and flow control after the fault, thereby improving the system power supply reliability.

[0128] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A fault isolation method for a power distribution system, characterized in that: The power distribution system is a topological structure based on a multi-port chain battery energy storage system, the power distribution system includes at least one power supply line, and a circuit breaker is installed between the port inductance of each power supply line and a common connection point. The method includes: In the case where the power distribution system includes a plurality of the power supply lines, acquiring power flow parameters of each of the power supply lines in the power distribution system, the power flow parameters at least including a collection current and a collection voltage; When a power flow parameter of at least one of the power supply lines is not within a corresponding threshold range, determining that a fault occurs in the power distribution system; In the event of a short circuit fault in the power distribution system, determining the power supply line with the largest collected current as a fault line; Sending a tripping signal to the circuit breaker of the fault line to control the circuit breaker of the fault line to trip instantly, so as to cut off the connection between the fault line and the power distribution system and complete fault isolation; A corresponding half-bridge power flow control module is connected between the port inductor of the power supply line and the DC bus, the half-bridge power flow control module includes a first power module on a first bridge wall and a second power module on a second bridge wall, the second power module is connected in parallel with a thyristor bypass switch, and when a power flow parameter of at least one of the power supply lines is not within a corresponding threshold range, determining that a fault occurs in the power distribution system includes: When the collected current of the power supply line is greater than the first protection setting value, and the zero-sequence current component of the power supply line is greater than the second protection setting value, it is determined that a short circuit fault occurs in the power distribution system, and all power devices in the half-bridge power flow control module are controlled to be locked, and after the dead time, the thyristor bypass switch is turned on; When the collected current of the power supply line is greater than the first protection setting value, and the zero-sequence current component of the power supply line is less than the second protection setting value, it is determined that a phase-to-phase short circuit fault occurs in the power distribution system; When the zero-sequence current component of the power supply line is greater than a current reference value, it is determined that a ground short circuit fault occurs in the power distribution system, and the current reference value is less than the first protection setting value and the second protection setting value.

2. The method according to claim 1, characterized in that The power supply lines include a first power supply line, a second power supply line and a third power supply line. When a short circuit fault occurs in the power distribution system, before determining the power supply line with the largest collected current as a faulty line, the method further includes: In the case where a three-phase short circuit occurs in the second power supply line at the historical moment, according to the first current formula and the second current formula , respectively determine the three-phase current of the first power supply line and the three-phase current of the third power supply line, wherein, is the three-phase current of the first power supply line, is the three-phase current of the third power supply line, is the equivalent electromotive force of the first power supply line, is the equivalent electromotive force of the third power supply line, is the equivalent transformer impedance of the first power supply line, is the equivalent transformer impedance of the third power supply line, is the equivalent inductance of the first power supply line, is the equivalent inductance of the third power supply line, ω is the angular frequency, and Lc represents the filter inductance of the power supply line; According to the KCL law, the three-phase short-circuit current of the second power supply line is determined to be the sum of the three-phase current of the first power supply line and the three-phase current of the third power supply line.

3. The method according to claim 1, characterized in that The power distribution system includes a first power supply line, a second power supply line, and a third power supply line. When a short circuit fault occurs in the power distribution system, before determining the power supply line with the largest collected current as a faulty line, the method further includes: In the case of a two-phase short circuit fault in the second power supply line at the historical moment, according to the positive sequence component formula of the first phase A current The positive and negative zero-sequence phase rotation relationship of the ABC three-phase , determine the two-phase short-circuit current of the second power supply line, the two-phase short-circuit fault is a B-phase short-circuit fault and a C-phase short-circuit fault, wherein, is the positive sequence component of phase A current, is the A phase current, is the negative sequence component of phase A current, is the zero-sequence component of phase A current, is the B phase current, is the C phase current, is the rotation factor, is the positive sequence equivalent reactance of non-fault phase A, is the negative sequence equivalent reactance of non-fault phase A; Based on the KCL law, it is determined that the B-phase short-circuit current of the second power supply line is the sum of the B-phase current of the first power supply line and the B-phase current of the third power supply line, and the C-phase short-circuit current of the second power supply line is the sum of the C-phase current of the first power supply line and the C-phase current of the third power supply line.

4. The method according to claim 3, characterized in that The power distribution system includes a first power supply line, a second power supply line, and a third power supply line. When a short circuit fault occurs in the power distribution system, before determining the power supply line with the largest collected current as a faulty line, the method further includes: In the case of a two-phase ground short circuit fault on the second power supply line at the historical moment, according to the second A phase current positive sequence component formula and the positive and negative zero-sequence phasor rotation relationship of the three-phase ABC, determine the two-phase short-circuit current of the second power supply line, the two-phase ground short-circuit fault is a B-phase ground short-circuit fault and a C-phase ground short-circuit fault, wherein, is the positive sequence current of non-fault phase A, is the equivalent electromotive force of non-fault phase A, is the positive sequence equivalent reactance of non-fault phase A, is the negative sequence equivalent reactance of non-fault phase A, is the zero-sequence equivalent reactance of non-fault phase A, is the transition resistance; Based on the KCL law, it is determined that the B-phase short-circuit current of the second power supply line is the sum of the B-phase current of the first power supply line and the B-phase current of the third power supply line, and the C-phase short-circuit current of the second power supply line is the sum of the C-phase current of the first power supply line and the C-phase current of the third power supply line.

5. The method according to claim 1, characterized in that The power distribution system includes a first power supply line, a second power supply line, and a third power supply line. When a short circuit fault occurs in the power distribution system, before determining the power supply line with the largest collected current as a faulty line, the method further includes: When a single-phase short circuit fault occurs in the second power supply line at a historical moment, obtaining a phase A short circuit current of a short circuit point on the second power supply line; According to the A-phase short-circuit current and single-phase current formula of the short-circuit point on the second power supply line , determine the single-phase short-circuit current of the second power supply line, wherein, is the positive sequence component of phase A current, is the A phase current, is the negative sequence component of phase A current, is the zero-sequence component of phase A current; Based on the KCL law, it is determined that the single-phase short-circuit current of the second power supply line is the sum of the single-phase current of the first power supply line and the single-phase current of the third power supply line.

6. The method according to claim 5, characterized in that Obtaining the A-phase short-circuit current of the short-circuit point on the second power supply line, including: Based on the A phase short circuit formula , determine the A-phase short-circuit current of the short-circuit point on the second power supply line, wherein, is the positive sequence current of non-fault phase A, is the negative sequence current of non-fault phase A, is the zero-sequence current of non-fault phase A, is the equivalent electromotive force of non-fault phase A, is the positive sequence equivalent reactance of non-fault phase A, is the negative sequence equivalent reactance of non-fault phase A, is the zero-sequence equivalent reactance of non-fault phase A, is the transition resistor.

7. A fault isolation device for a power distribution system, characterized in that: The power distribution system is a topological structure based on a multi-port chain battery energy storage system, the power distribution system includes at least one power supply line, a circuit breaker is installed between the port inductance of each power supply line and a common connection point, and the device includes: An acquisition unit, configured to acquire, when the power distribution system includes a plurality of power supply lines, power flow parameters of each of the power supply lines in the power distribution system, wherein the power flow parameters at least include a collection current and a collection voltage; A first determining unit, configured to determine that a fault occurs in the power distribution system when a power flow parameter of at least one of the power supply lines is not within a corresponding threshold range; A second determining unit is used to determine the power supply line with the largest collected current as a fault line when a short circuit fault occurs in the power distribution system; A fault isolation unit, used for sending a trip signal to the circuit breaker of the fault line to control the circuit breaker of the fault line to trip instantly, so as to cut off the connection between the fault line and the power distribution system and complete the fault isolation; A corresponding half-bridge power flow control module is connected between the port inductor of the power supply line and the DC bus, the half-bridge power flow control module comprises a first power module on the first bridge wall and a second power module on the second bridge wall, the second power module is connected in parallel with the thyristor bypass switch; The first determination unit includes a first determination module, a second determination module and a third determination module. The first determination module is used to determine that a short circuit fault occurs in the distribution system when the collected current of the power supply line is greater than the first protection setting value and the zero-sequence current component of the power supply line is greater than the second protection setting value, and control all power devices in the half-bridge power flow control module to lock, and turn on the thyristor bypass switch after the dead time; the second determination module is used to determine that a phase-to-phase short circuit fault occurs in the distribution system when the collected current of the power supply line is greater than the first protection setting value and the zero-sequence current component of the power supply line is less than the second protection setting value; the third determination module is used to determine that a ground short circuit fault occurs in the distribution system when the zero-sequence current component of the power supply line is greater than a current reference value, and the current reference value is less than the first protection setting value and the second protection setting value.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored program, wherein when the program is executed, the device where the computer-readable storage medium is located is controlled to execute the fault isolation method for the power distribution system according to any one of claims 1 to 6.

9. An electronic device, characterized in that: include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the one or more programs include a method for executing the fault isolation method of the power distribution system described in any one of claims 1 to 6.

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