Power protection system, control method and related product

Abstract

The invention discloses an electric power protection system, a control method and a related product. The power protection system comprises a controller, a switch assembly and a three-phase shunt reactor, the three first ends of the switch assembly are connected with the three-phase alternating current circuits in a one-to-one correspondence mode, the three second ends of the switch assembly are connected with the first ends of the three-phase shunt reactors in a one-to-one correspondence mode, and the second ends of the three-phase shunt reactors are connected together. A controller configured to obtain a three-phase AC voltage and a three-phase AC current; obtaining three-phase interphase impedance according to the three-phase alternating voltage and the three-phase alternating current; according to the three-phase interphase impedance, judging whether the reactor has a turn-to-turn short circuit fault or not; and under the condition that the reactor has a turn-to-turn short circuit fault, the switch assembly is controlled to be switched off. According to the embodiment of the invention, whether the reactor has the turn-to-turn short circuit fault or not is judged through the three-phase interphase impedance, and the switch assembly is controlled to be switched off under the condition that the reactor has the turn-to-turn short circuit fault, so that the safety of a power grid is improved.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a power protection system, control method and related products. Background Technology

[0002] Parallel dry-type air-core reactors are widely used in power systems with voltage levels of 35kV and below to compensate for capacitive reactive power due to their advantages such as high linearity, no core saturation, simple structure, and convenient maintenance. The reactor consists of multi-layer coils wound with multiple parallel conductors. Manufacturing defects, material aging, overvoltage surges, mechanical vibration, or dust and moisture accumulation can lead to a decline in inter-turn insulation performance, resulting in inter-turn short circuits and threatening power grid safety.

[0003] In related technologies, the direction of zero-sequence voltage and zero-sequence current is used to determine whether an inter-turn short-circuit fault has occurred in a reactor. However, in power systems with an ungrounded neutral point, there is no zero-sequence current, making it impossible to determine whether an inter-turn fault has occurred in a reactor by using the direction of zero-sequence voltage and zero-sequence current, thus reducing the safety of the power grid. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a power protection system, control method, and related products to improve the security of the power grid.

[0005] The embodiments of this application disclose the following technical solutions: In a first aspect, embodiments of this application provide a power protection system, including: a controller, a switching assembly, and a three-phase parallel reactor; The three first terminals of the switching assembly are connected to the three-phase AC circuit one by one, and the three second terminals of the switching assembly are connected to the first terminals of the three-phase parallel reactor one by one. The second terminals of the three-phase parallel reactor are connected together. The controller is configured to acquire three-phase AC voltage and three-phase AC current; obtain three-phase phase-to-phase impedance based on the three-phase AC voltage and three-phase AC current; determine whether the reactor has experienced an inter-turn short-circuit fault based on the three-phase phase-to-phase impedance; and control the switching assembly to disconnect if an inter-turn short-circuit fault occurs in the reactor.

[0006] In one possible implementation, the controller is configured to determine whether an inter-turn short-circuit fault has occurred in the target phase reactor when both phase-to-phase impedances corresponding to the target are less than a preset threshold.

[0007] In one possible implementation, the controller is configured to, in the event of an inter-turn short-circuit fault in the reactor, obtain a first negative-sequence voltage and a first negative-sequence current based on the three-phase AC voltage and the three-phase AC current; compensate the first negative-sequence voltage based on the first negative-sequence voltage and the first negative-sequence current to obtain a second negative-sequence voltage; and control the switching assembly to turn off when the phase difference between the second negative-sequence voltage and the first negative-sequence current is within a first preset range.

[0008] In one possible implementation, the controller is configured to determine whether a voltage transformer open-circuit fault or a current transformer open-circuit fault has occurred if the phase difference between the second negative-sequence voltage and the first negative-sequence current is within a first preset range; and to control the switching assembly to turn off if no voltage transformer open-circuit fault or current transformer open-circuit fault has occurred; wherein the voltage transformer is configured to acquire three-phase AC voltage and the current transformer is configured to acquire three-phase AC current.

[0009] In one possible implementation, the three-phase interphase impedance includes the average value of the N-cycle three-phase interphase impedance.

[0010] In one possible implementation, the controller is configured to, for any target phase, obtain the secondary rated impedance of the target reactor based on the rated voltage of the target reactor, the three-phase rated capacity of the target reactor, the turns ratio of the target voltage transformer, and the turns ratio of the target current transformer; and obtain a preset threshold corresponding to the target based on the secondary rated impedance of the target reactor, the three-phase phase-to-phase impedance, and the impedance drop rate corresponding to the preset inter-turn short-circuit ratio.

[0011] In one possible implementation, the controller is configured to compensate the first negative-sequence voltage based on the first negative-sequence voltage, the first negative-sequence current, and a compensation coefficient to obtain a second negative-sequence voltage; wherein, when the amplitude of the first negative-sequence voltage is less than the lower limit of a second preset interval, the compensation coefficient is a first set value; when the amplitude of the first negative-sequence voltage is greater than or equal to the lower limit of the second preset interval and less than the upper limit of the interval, the compensation coefficient is a second set value; when the amplitude of the first negative-sequence voltage is greater than or equal to the upper limit of the second preset interval, the compensation coefficient is a third set value; wherein the first set value is greater than the second set value, and the second set value is greater than the third set value.

[0012] Secondly, embodiments of this application provide a control method for a power protection system, the power protection system including a switching assembly and a three-phase parallel reactor; wherein, the three first terminals of the switching assembly are respectively connected to the three-phase parallel reactor in a one-to-one correspondence, the three second terminals of the switching assembly are respectively connected to the first terminals of the three-phase parallel reactor in a one-to-one correspondence, and the second terminals of the three-phase parallel reactor are connected together. The methods include: Obtain three-phase AC voltage and three-phase AC current; The three-phase phase impedance is obtained from the three-phase AC voltage and three-phase AC current; Determine whether the reactor has experienced an inter-turn short circuit fault based on the three-phase phase impedance; In the event of an inter-turn short circuit fault in the reactor, the control switch assembly disconnects.

[0013] In one possible implementation, the inter-turn short-circuit fault of the reactor is determined based on the three-phase inter-phase impedance. Specifically, if the inter-phase impedances of the two phases corresponding to the target are both less than a preset threshold, it is determined that the target phase reactor has an inter-turn short-circuit fault.

[0014] In one possible implementation, when an inter-turn short-circuit fault occurs in the reactor, the control switch assembly is disconnected, specifically including: when an inter-turn short-circuit fault occurs in the reactor, obtaining a first negative sequence voltage and a first negative sequence current based on the three-phase AC voltage and the three-phase AC current; compensating the first negative sequence voltage based on the first negative sequence voltage and the first negative sequence current to obtain a second negative sequence voltage; and when the phase difference between the second negative sequence voltage and the first negative sequence current is within a first preset interval, controlling the switch assembly to turn off.

[0015] In one possible implementation, when the phase difference between the second negative-sequence voltage and the first negative-sequence current is within a first preset range, the control switch assembly is turned off. Specifically, this includes: when the phase difference between the second negative-sequence voltage and the first negative-sequence current is within the first preset range, determining whether a voltage transformer open-circuit fault or a current transformer open-circuit fault has occurred; and when no voltage transformer open-circuit fault or current transformer open-circuit fault has occurred, controlling the switch assembly to turn off; wherein the voltage transformer is configured to acquire three-phase AC voltage, and the current transformer is configured to acquire three-phase AC current.

[0016] Thirdly, embodiments of this application provide a control device, including a processor and a memory. The memory is used to store programs, instructions, or code, and the processor is used to execute the programs, instructions, or code in the memory to perform the control method of the power protection system as described in any embodiment of the second aspect.

[0017] Fourthly, embodiments of this application provide a computer-readable storage medium storing a computer program, which is loaded by a processor to execute the control method of the power protection system as described in any embodiment of the second aspect.

[0018] To improve power grid security, this application provides a power protection system, including: a controller, a switching assembly, and a three-phase parallel reactor; wherein, the three first terminals of the switching assembly are respectively connected to the three-phase AC circuit, and the three second terminals of the switching assembly are respectively connected to the first terminals of the three-phase parallel reactor, and the second terminals of the three-phase parallel reactor are connected together; the controller is configured to acquire the three-phase AC voltage and the three-phase AC current; obtain the three-phase interphase impedance based on the three-phase AC voltage and the three-phase AC current; determine whether the reactor has experienced an inter-turn short-circuit fault based on the three-phase interphase impedance; and control the switching assembly to disconnect when an inter-turn short-circuit fault occurs in the reactor.

[0019] In this embodiment of the application, the three-phase neutral point of the power protection system, i.e., the second end of the three-phase parallel reactor, is connected together instead of being grounded. Therefore, this embodiment of the application determines whether an inter-turn short-circuit fault has occurred in the reactor by the three-phase phase-to-phase impedance, and controls the switching assembly to disconnect when an inter-turn short-circuit fault occurs in the reactor, thereby improving the safety of the power grid. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A schematic diagram of a power protection system provided in an embodiment of this application; Figure 2 A schematic diagram illustrating a method for determining a voltage transformer open-circuit fault, provided as an embodiment of this application; Figure 3 A flowchart of a control method for a power protection system provided in an embodiment of this application; Figure 4 A flowchart illustrating another control method for a power protection system provided in this application embodiment; Figure 5 A flowchart illustrating another control method for a power protection system provided in this application embodiment; Figure 6 This is a schematic diagram of a control device provided in an embodiment of this application. Detailed Implementation

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

[0023] The terms "first" and "second," etc., used in the specification and claims of this application are used to distinguish different objects, not to describe a specific order of objects. For example, "first operation instruction" and "second operation instruction," etc., are used to distinguish different operation instructions, not to describe a specific order of operation instructions.

[0024] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0025] In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more, for example, multiple processing units means two or more processing units, multiple elements means two or more elements, etc.

[0026] The technical solution of this application will be described below with reference to the accompanying drawings.

[0027] See Figure 1 This figure is a schematic diagram of a power protection system provided in an embodiment of this application.

[0028] like Figure 1 As shown, the power protection system includes: a controller (not shown in the figure), a switch assembly 100, and reactors (200-400). The three first terminals of the switch assembly 100 are respectively connected to the three-phase AC circuit (phase A, phase B, and phase C). The three second terminals of the switch assembly 100 are respectively connected to the first terminals of the three-phase parallel reactors (reactors 200, 300, and 400). The second terminals of the three-phase parallel reactors (reactors 200, 300, and 400) are connected together, forming the neutral point N.

[0029] In one embodiment, the controller (not shown) is configured to acquire three-phase AC voltage and three-phase AC current; obtain three-phase phase-to-phase impedance based on the three-phase AC voltage and three-phase AC current; determine whether an inter-turn short-circuit fault has occurred in the reactor based on the three-phase phase-to-phase impedance; and control the switching assembly to disconnect in the event of an inter-turn short-circuit fault in the reactor.

[0030] The following section will introduce the methods for obtaining three-phase AC voltage and three-phase AC current.

[0031] The embodiments of this application do not specifically limit the method of obtaining three-phase AC voltage and three-phase AC current. For example, the voltage of phase A, phase B, and phase C can be obtained by voltage transformers PTA, PTB, and PTC, respectively; and the current of phase A, phase B, and phase C can be obtained by current transformers CTA, CTB, and CTC, respectively.

[0032] The following section will introduce the methods for calculating the interphase impedance of three phases.

[0033] In one possible implementation, the three-phase interphase impedance is calculated using the following formula (1): (1) The three-phase interphase impedances, namely interphase impedance ZAB, interphase impedance ZBC and interphase impedance ZCA, can be calculated using the above formula (1).

[0034] In one possible implementation, the three-phase interphase impedance is calculated using the following formula (2): (2) Where N is the number of sampling points per cycle. In this embodiment, the average value of the effective value of the interphase impedance per cycle is used as the calculated value of the interphase impedance to reduce the influence of frequency offset or system oscillation on the interphase impedance, thereby improving the accuracy of the interphase impedance.

[0035] It should be understood that for a given target phase, there are two corresponding interphase impedances. For example, if phase A is the target phase, its corresponding interphase impedances are ZAB and ZCA; if phase B is the target phase, its corresponding interphase impedances are ZAB and ZBC; and if phase C is the target phase, its corresponding interphase impedances are ZCA and ZBC.

[0036] The following section will introduce the methods for determining whether an inter-turn short circuit fault has occurred in a reactor.

[0037] If the inter-phase impedances of the two phases corresponding to the target are both less than the preset threshold, determine whether the target phase reactor has experienced an inter-turn short-circuit fault.

[0038] When the phase-to-phase impedances corresponding to A, namely the phase-to-phase impedances ZAB and ZCA, are both less than the preset threshold, reactor 200 experiences an inter-turn short-circuit fault; when the phase-to-phase impedances corresponding to B, namely the phase-to-phase impedances ZBC and ZAB, are both less than the preset threshold, reactor 300 experiences an inter-turn short-circuit fault; when the phase-to-phase impedances corresponding to C, namely the phase-to-phase impedances ZCA and ZBC, are both less than the preset threshold, reactor 400 experiences an inter-turn short-circuit fault.

[0039] This application provides a method for determining a preset threshold, namely, for any target phase, the secondary rated impedance of the target reactor is obtained based on the rated voltage of the target reactor, the three-phase rated capacity of the target reactor, the turns ratio of the target voltage transformer, and the turns ratio of the target current transformer; and the preset threshold corresponding to the target is obtained based on the secondary rated impedance of the target reactor, the three-phase phase impedance, and the impedance reduction rate corresponding to the preset inter-turn short-circuit ratio.

[0040] For example, taking phase A as the target phase, its corresponding preset threshold is K1. Z set K1 is calculated based on the impedance reduction rate under the inter-turn short-circuit ratio.

[0041] The secondary rated impedance of the reactor is Z 2n The calculation method is as follows: (3) (3) Among them, U 1n S is the rated voltage on the reactor nameplate. n The rated capacity of the reactor nameplate is n (three-phase capacity). CT For CT ratio, n PT For PT ratio.

[0042] Interphase impedance setting Z set The calculation method is shown in the following formula (4): (4) Among them, Z max This represents the maximum value among the three-phase interphase impedances, namely the maximum value among interphase impedances ZAB, ZBC, and ZCA.

[0043] In this embodiment of the application, the three-phase neutral point N of the power protection system is not grounded. Therefore, this embodiment of the application determines whether an inter-turn short-circuit fault has occurred in the reactor by the three-phase phase-to-phase impedance, and controls the switching assembly to disconnect when an inter-turn short-circuit fault occurs in the reactor, thereby improving the safety of the power grid.

[0044] In another embodiment, the controller (not shown in the figure) is configured to acquire three-phase AC voltage and three-phase AC current; obtain three-phase phase-to-phase impedance based on the three-phase AC voltage and three-phase AC current; determine whether an inter-turn short-circuit fault has occurred in the reactor based on the three-phase phase-to-phase impedance; in the case of an inter-turn short-circuit fault in the reactor, obtain a first negative-sequence voltage and a first negative-sequence current based on the three-phase AC voltage and three-phase AC current; compensate the first negative-sequence voltage based on the first negative-sequence voltage and the first negative-sequence current to obtain a second negative-sequence voltage; and control the switching assembly to turn off when the phase difference between the second negative-sequence voltage and the first negative-sequence current is within a first preset interval.

[0045] It should be understood that the specific value of the first preset interval is not specifically limited in the embodiments of this application, and can be set according to actual needs. For example, the first preset interval in the embodiments of this application can be set to [-180°, 0°].

[0046] The first negative sequence voltage and the first negative sequence current are calculated using the following formulas (5) and (6), respectively: (5) (6) Among them, U A U B and U C Let I be the three-phase voltage phasors, respectively. A I B and I C These are the three-phase current phasors, where U1 is the first negative-sequence voltage, I1 is the first negative-sequence current, and α is the phasor operator. .

[0047] The second negative sequence voltage is calculated according to the following formula (7): (7) Where U2 is the second negative sequence voltage, K2 is the compensation coefficient, and Z 2n The rated secondary impedance of the reactor.

[0048] Based on the above formula (7), this application embodiment provides a method for determining the compensation coefficient. When the amplitude of the first negative sequence voltage is less than the lower limit of the second preset interval, the compensation coefficient is a first set value; when the amplitude of the first negative sequence voltage is greater than or equal to the lower limit of the second preset interval and less than the upper limit of the interval, the compensation coefficient is a second set value; when the amplitude of the first negative sequence voltage is greater than or equal to the upper limit of the second preset interval, the compensation coefficient is a third set value; wherein, the first set value is greater than the second set value, and the second set value is greater than the third set value.

[0049] For example, the lower limit of the second preset interval is 1V, and the upper limit of the second preset interval is 2V. When the amplitude of the first negative sequence voltage U1 is less than 1V, the compensation coefficient K2 = 0.8, which is the first preset value; when the amplitude of the first negative sequence voltage U1 is greater than or equal to 1V and less than 2V, the compensation coefficient is K2 = (2 - U1)0.8, which is the second preset value; when the amplitude of the first negative sequence voltage U1 is greater than or equal to 2V, the compensation coefficient K2 = 0, which is the third preset value.

[0050] In this embodiment, two methods are used to comprehensively determine whether an impedance has an inter-turn short-circuit fault, thereby improving the accuracy of inter-turn short-circuit fault detection and thus enhancing the safety of the power grid. The first method determines the inter-turn short-circuit fault based on the inter-turn impedance; the second method determines the inter-turn short-circuit fault based on the phase relationship between negative-sequence voltage and negative-sequence current.

[0051] In addition, to avoid the inability to determine the inter-turn short-circuit fault of the impedance device based on the phase relationship between the negative sequence voltage and the negative sequence current due to the negative sequence voltage being too small, the negative sequence voltage (first negative sequence voltage) is compensated in this embodiment, and the inter-turn short-circuit fault of the impedance device is detected based on the phase relationship between the compensated negative sequence voltage (second negative sequence voltage) and the negative sequence current, thereby further improving the safety of the power grid.

[0052] In another embodiment, the controller (not shown in the figure) is configured to acquire three-phase AC voltage and three-phase AC current; obtain three-phase phase-to-phase impedance based on the three-phase AC voltage and three-phase AC current; determine whether an inter-turn short-circuit fault has occurred in the reactor based on the three-phase phase-to-phase impedance; if an inter-turn short-circuit fault has occurred in the reactor, obtain a first negative-sequence voltage and a first negative-sequence current based on the three-phase AC voltage and three-phase AC current; compensate the first negative-sequence voltage based on the first negative-sequence voltage and the first negative-sequence current to obtain a second negative-sequence voltage; if the phase difference between the second negative-sequence voltage and the first negative-sequence current is within a first preset interval, determine whether a voltage transformer open-circuit fault or a current transformer open-circuit fault has occurred; if no voltage transformer open-circuit fault or current transformer open-circuit fault has occurred, control the switching assembly to turn off.

[0053] It should be understood that in the event of a voltage transformer (PT) open-circuit fault and / or a current transformer (CT) open-circuit fault, the calculated three-phase phase-to-phase impedance values ​​obtained in this application embodiment are unreliable. Therefore, in this application embodiment, when neither the voltage transformer (PT) nor the current transformer (CT) experiences an open-circuit fault, i.e., the three-phase phase-to-phase impedance is reliable, the control switch assembly is disconnected to improve the accuracy of the power protection system and thus enhance the safety of the power grid.

[0054] The following embodiments of this application will describe the detection method for open circuit faults in voltage transformers.

[0055] Taking a 35kV power system as an example, the method for judging the open circuit fault of the voltage transformer (PT) is as follows: Figure 2 As shown, a voltage transformer (PT) is considered to have an open-circuit fault when at least one of the following conditions is met: In the first scenario, if all three-phase voltages are less than 8V and any phase current is greater than the effective phase current threshold of 0.05A, it is determined that the voltage transformer (PT) has a broken wire fault.

[0056] In the second scenario, if the self-generated 3U0 is greater than 8V and the difference between the maximum and minimum line voltages is greater than 16V, it is determined that the voltage transformer PT has a broken wire fault.

[0057] In the third scenario, if the self-generated 3U0 is greater than 8V and the maximum line voltage is less than 16V, it is determined that the voltage transformer PT has a broken wire fault.

[0058] A current transformer (CT) is considered to have an open-circuit fault if at least one of the following conditions is met: In the first case, if the maximum phase current is greater than 0.1In, it is determined that the current transformer CT has a broken wire fault; where In is the secondary rated value of the current transformer CT. In the second scenario, if the maximum value of the protection current is greater than three times the minimum value, or the minimum value is less than 0.06In, it is determined that the current transformer (CT) has a broken wire fault; where In is the secondary rated value of the current transformer (CT).

[0059] It should be understood that, in the embodiments of this application, the control switch assembly is closed in the event of a voltage transformer open circuit fault or a current transformer open circuit fault.

[0060] Based on the power protection system described in the foregoing embodiments, this application also provides a control method for the power protection system.

[0061] See Figure 3 The figure shows a control method for a power protection system provided in an embodiment of this application. The power protection system includes a switching assembly and a three-phase parallel reactor. The three first terminals of the switching assembly are respectively connected to the three-phase AC circuit, and the three second terminals of the switching assembly are respectively connected to the first terminals of the three-phase parallel reactor. The second terminals of the three-phase parallel reactor are connected together.

[0062] The method includes the following steps: S1000: Obtain three-phase AC voltage and three-phase AC current.

[0063] S2000: The three-phase phase impedance is obtained based on the three-phase AC voltage and three-phase AC current.

[0064] S3000: Determine whether the reactor has experienced an inter-turn short circuit fault based on the three-phase phase impedance.

[0065] S4000: In the event of an inter-turn short circuit fault in the reactor, the control switch assembly is disconnected.

[0066] In this embodiment of the application, the three-phase neutral point N of the power protection system is not grounded. Therefore, this embodiment of the application determines whether an inter-turn short-circuit fault has occurred in the reactor by the three-phase phase-to-phase impedance, and controls the switching assembly to disconnect when an inter-turn short-circuit fault occurs in the reactor, thereby improving the safety of the power grid.

[0067] like Figure 4 As shown in the embodiment of this application, another control method for a power protection system is provided, which includes the following steps: S1000: Obtain three-phase AC voltage and three-phase AC current.

[0068] S2000: The three-phase phase impedance is obtained based on the three-phase AC voltage and three-phase AC current.

[0069] S3000: Determine whether the reactor has experienced an inter-turn short circuit fault based on the three-phase phase impedance.

[0070] S4000: In the event of an inter-turn short-circuit fault in the reactor, the first negative sequence voltage and the first negative sequence current are obtained based on the three-phase AC voltage and the three-phase AC current.

[0071] S5000: The first negative sequence voltage is compensated based on the first negative sequence voltage and the first negative sequence current to obtain the second negative sequence voltage.

[0072] S6000: When the phase difference between the second negative sequence voltage and the first negative sequence current is within a first preset range, the control switch assembly is turned off.

[0073] In this embodiment, two methods are used to comprehensively determine whether an impedance has an inter-turn short-circuit fault, thereby improving the accuracy of inter-turn short-circuit fault detection and thus enhancing the safety of the power grid. The first method determines the inter-turn short-circuit fault based on the inter-turn impedance; the second method determines the inter-turn short-circuit fault based on the phase relationship between negative-sequence voltage and negative-sequence current.

[0074] like Figure 5 As shown in the embodiment of this application, another control method for a power protection system is provided, which includes the following steps: S1000: Obtain three-phase AC voltage and three-phase AC current.

[0075] S2000: The three-phase phase impedance is obtained based on the three-phase AC voltage and three-phase AC current.

[0076] S3000: Determine whether the reactor has experienced an inter-turn short circuit fault based on the three-phase phase impedance.

[0077] S4000: In the event of an inter-turn short-circuit fault in the reactor, the first negative sequence voltage and the first negative sequence current are obtained based on the three-phase AC voltage and the three-phase AC current.

[0078] S5000: The first negative sequence voltage is compensated based on the first negative sequence voltage and the first negative sequence current to obtain the second negative sequence voltage.

[0079] S6000: If the phase difference between the second negative sequence voltage and the first negative sequence current is within the first preset range, determine whether a voltage transformer open circuit fault or a current transformer open circuit fault has occurred.

[0080] S7000: Controls the switch assembly to shut off in the absence of a voltage transformer open circuit fault or a current transformer open circuit fault.

[0081] Because the calculated three-phase phase-to-phase impedance values ​​obtained in this application embodiment are unreliable in the event of a voltage transformer (PT) open-circuit fault and / or a current transformer (CT) open-circuit fault, this application embodiment controls the switching assembly to disconnect when neither the voltage transformer (PT) nor the current transformer (CT) experiences an open-circuit fault, i.e., when the three-phase phase-to-phase impedance is reliable. This improves the accuracy of the power protection system and thus enhances the safety of the power grid.

[0082] In one possible implementation, the determination of whether an inter-turn short-circuit fault has occurred in the reactor is based on the three-phase inter-phase impedance. Specifically, this includes determining whether an inter-turn short-circuit fault has occurred in the target phase reactor when the inter-phase impedances of the two corresponding phases are both less than a preset threshold.

[0083] In one possible implementation, the three-phase interphase impedance includes the average value of the N-cycle three-phase interphase impedance.

[0084] In one possible implementation, the preset threshold corresponding to the target is calculated as follows: For any target phase, the secondary rated impedance of the target reactor is obtained based on the rated voltage of the target reactor, the three-phase rated capacity of the target reactor, the transformation ratio of the target voltage transformer, and the transformation ratio of the target current transformer; the preset threshold corresponding to the target is obtained based on the secondary rated impedance of the target reactor, the three-phase phase impedance, and the impedance drop rate corresponding to the preset inter-turn short-circuit ratio.

[0085] See Figure 6The figure is a schematic diagram of a control device provided in an embodiment of this application.

[0086] The control device may include a memory 1011 and a processor 1012. The processor 1012 can be connected to the power protection system and can drive various switching devices in the power protection system. Figure 6 As shown, the memory can be random access memory (RAM), flash memory, read-only memory (ROM), EPROM, non-volatile read-only memory (Electronic Programmable ROM), registers, hard disks, removable disks, etc.

[0087] The memory 1011 can store computer instructions. When the computer instructions stored in the memory 1011 are executed by the processor 1012, the processor 1012 can use them to execute the control method of the power protection system. The memory 1011 can also store data, such as preset ranges, preset thresholds, and other information involved in the above embodiments.

[0088] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape) or a semiconductor medium (e.g., solid-state disk (SSD)).

[0089] This application also provides a readable storage medium for storing the methods provided in the above embodiments. Examples include random access memory (RAM), flash memory, read-only memory (ROM), EPROM, non-volatile read-only memory (EPROM), registers, hard disks, removable disks, or any other form of storage medium in the art.

[0090] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. Regarding the methods disclosed in the embodiments, since they correspond to the product embodiments disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the description of the product embodiments.

[0091] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electrical protection system, characterized in that, The application relates to a controller, a switch assembly and a three-phase parallel reactor. Three first ends of the switch assembly are connected with three-phase alternating current circuits one by one, three second ends of the switch assembly are connected with first ends of the three-phase parallel reactor one by one, and second ends of the three-phase parallel reactor are connected together. The controller is configured to acquire three-phase alternating current voltage and three-phase alternating current, obtain three-phase inter-phase impedance according to the three-phase alternating current voltage and the three-phase alternating current, judge whether a reactor has a turn-to-turn short-circuit fault according to the three-phase inter-phase impedance, and control the switch assembly to be turned off in the case that the reactor has the turn-to-turn short-circuit fault. The controller is configured to judge whether a target-phase reactor has a turn-to-turn short-circuit fault in the case that two inter-phase impedances corresponding to the target phase are both less than a preset threshold.

2. The power protection system of claim 1, wherein, The controller is configured to obtain first negative sequence voltage and first negative sequence current according to the three-phase alternating current voltage and the three-phase alternating current in the case that the reactor has the turn-to-turn short-circuit fault, compensate the first negative sequence voltage according to the first negative sequence voltage and the first negative sequence current, and obtain second negative sequence voltage.

3. The power protection system of claim 1, wherein, The controller is configured to control the switch assembly to be turned off in the case that a phase difference value between the second negative sequence voltage and the first negative sequence current is in a first preset interval. The controller is configured to judge whether a voltage transformer breakage fault or a current transformer breakage fault occurs in the case that the phase difference value between the second negative sequence voltage and the first negative sequence current is in the first preset interval, and control the switch assembly to be turned off in the case that the voltage transformer breakage fault or the current transformer breakage fault does not occur.

4. The power protection system of claim 3, wherein, The three-phase inter-phase impedance comprises an average value of N-cycle three-phase inter-phase impedance.

5. The power protection system of any of claims 1-4, wherein, The controller is configured to obtain secondary rated impedance of a target reactor according to rated voltage of the target reactor, three-phase rated capacity of the target reactor, target voltage transformer transformation ratio and target current transformer transformation ratio for any target phase.

6. The power protection system of claim 2, wherein, The controller is configured to obtain the preset threshold corresponding to the target phase according to the secondary rated impedance of the target reactor, the three-phase inter-phase impedance and impedance drop rate corresponding to a preset turn-to-turn short-circuit ratio. The controller is configured to compensate the first negative sequence voltage according to the first negative sequence voltage, the first negative sequence current and a compensation coefficient, and obtain second negative sequence voltage; wherein the compensation coefficient is a first set value in the case that an amplitude of the first negative sequence voltage is less than a lower limit value of a second preset interval, the compensation coefficient is a second set value in the case that the amplitude of the first negative sequence voltage is greater than or equal to the lower limit value of the second preset interval and less than an upper limit value of the interval, and the compensation coefficient is a third set value in the case that the amplitude of the first negative sequence voltage is greater than or equal to the upper limit value of the second preset interval; wherein the first set value is greater than the second set value, and the second set value is greater than the third set value.

7. The power protection system of claim 3, wherein, ​ 8. A control method of a power protection system, characterized by, The power protection system comprises a switch assembly and a three-phase shunt reactor; wherein three first ends of the switch assembly are connected to three-phase alternating current circuits one by one, three second ends of the switch assembly are connected to first ends of the three-phase shunt reactor one by one, and second ends of the three-phase shunt reactor are connected together. The method comprises: obtaining three-phase alternating current voltage and three-phase alternating current; obtaining three-phase inter-phase impedance according to the three-phase alternating current voltage and the three-phase alternating current; judging whether the reactor has an inter-turn short-circuit fault according to the three-phase inter-phase impedance; in the case that the reactor has an inter-turn short-circuit fault, controlling the switch assembly to be turned off.

9. The method of claim 8, wherein, The judging whether the reactor has an inter-turn short-circuit fault according to the three-phase inter-phase impedance specifically comprises: in the case that two of the inter-phase impedance corresponding to a target phase are both less than a preset threshold, judging that the reactor corresponding to the target phase has an inter-turn short-circuit fault.

10. The method of claim 8, wherein, The controlling the switch assembly to be turned off in the case that the reactor has an inter-turn short-circuit fault specifically comprises: in the case that the reactor has an inter-turn short-circuit fault, obtaining first negative sequence voltage and first negative sequence current according to the three-phase alternating current voltage and the three-phase alternating current; obtaining second negative sequence voltage by compensating the first negative sequence voltage according to the first negative sequence voltage and the first negative sequence current; in the case that a phase difference value between the second negative sequence voltage and the first negative sequence current is within a first preset interval, controlling the switch assembly to be turned off.

11. The method of claim 10, wherein, The controlling the switch assembly to be turned off in the case that the phase difference value between the second negative sequence voltage and the first negative sequence current is within the first preset interval specifically comprises: in the case that the phase difference value between the second negative sequence voltage and the first negative sequence current is within the first preset interval, judging whether a voltage transformer disconnection fault or a current transformer disconnection fault occurs; in the case that no voltage transformer disconnection fault or current transformer disconnection fault occurs, controlling the switch assembly to be turned off; wherein the voltage transformer is configured to obtain the three-phase alternating current voltage, and the current transformer is configured to obtain the three-phase alternating current.

12. A control device characterized by comprising: The power protection system comprises a processor and a memory, the memory is used to store programs, instructions or codes, and the processor is used to execute the programs, instructions or codes in the memory to complete the control method of the power protection system according to any one of claims 8-11.

13. A computer-readable storage medium, characterized in that, A computer program is stored, and the computer program is loaded by a processor to execute the control method of the power protection system according to any one of claims 8-11.

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