Alternating current filter switching inrush current suppression circuit, control method thereof and converter station
By connecting a dynamic closing resistor and capacitor in parallel in the circuit breaker and combining current and voltage transformer measurement to accurately control the closing time, the problem of unsatisfactory closing inrush current suppression of the AC filter is solved, achieving more efficient inrush current suppression and extending equipment life.
Patent Information
- Application Number
- CN202510875210.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-27
- Publication Date
- 2025-09-12
AI Technical Summary
In the prior art, the AC filter has an unsatisfactory effect in suppressing the closing inrush current. This is mainly due to the large dispersion of the closing time caused by the mechanical wear and aging of the closing resistor switching switch, which makes it impossible to accurately close the circuit at the optimal time, resulting in poor inrush current suppression effect.
The circuit breaker structure adopts a dynamic closing resistor and capacitor in parallel. The closing inrush current is suppressed by controlling the resistance change of the dynamic closing resistor. Combined with the measurement data of the current transformer and voltage transformer, the closing time is accurately controlled to reduce mechanical impact.
It effectively suppresses the closing inrush current, improves the suppression effect of the closing inrush current, extends the life of the circuit breaker, and reduces equipment cost and complexity.
Smart Images
Figure CN120638264A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of power systems, and in particular to a circuit for suppressing closing inrush current of an AC filter, a control method thereof, and a converter station. Background Art
[0002] In UHVDC transmission projects, the converter station operates in both rectification and inversion states, which consumes a large amount of reactive power and is accompanied by the generation of a large amount of harmonics. AC filters are usually used for filtering, but the frequent operation of the AC filters and circuit breakers can cause serious closing inrush current and overvoltage problems. In related technologies, a closing resistor switching switch is used to close at the optimal closing time to suppress the closing inrush current of the AC filter. Since the closing resistor switching switch is closed and opened mechanically, after the closing resistor switching switch is frequently switched, as some of its internal structures wear and age, its closing time is prolonged, resulting in a large dispersion in its closing time, causing the AC filter circuit breaker to no longer be closed at the optimal closing time, resulting in poor inrush current suppression effect during closing. Summary of the Invention
[0003] Based on this, it is necessary to provide an AC filter closing inrush current suppression circuit and its control method, converter station, control device and storage medium that can improve the closing inrush current suppression effect in response to the above technical problems.
[0004] In a first aspect, the present application provides a circuit for suppressing an AC filter closing inrush current, comprising:
[0005] a circuit breaker, wherein a first end of the circuit breaker is electrically connected to the AC bus;
[0006] an AC filter group, wherein a first end of the AC filter group is electrically connected to a second end of the circuit breaker, and a second end of the AC filter group is grounded;
[0007] a controller, wherein a first end of the controller is electrically connected to a switch assembly in the circuit breaker and is configured to send a closing instruction or an opening instruction to the switch assembly;
[0008] Wherein, the circuit breaker includes a dynamic closing resistor and a capacitor connected in parallel with the switch assembly. In one embodiment, the switch assembly includes a main break and an auxiliary break;
[0009] Among them, the first end of the auxiliary break is electrically connected to the AC bus, the second end of the auxiliary break is electrically connected to the first end of the main break, and the second end of the main break is electrically connected to the AC filter group; the main break is used to coordinate with the auxiliary break to control the on and off between the AC filter group and the AC bus.
[0010] In one embodiment, two ends of the dynamic closing resistor are electrically connected to two ends of the auxiliary break, and two ends of the capacitor are electrically connected to two ends of the main break.
[0011] In one embodiment, the resistance of the dynamic closing resistor is Ω; t represents time.
[0012] In one embodiment, it further includes a current transformer and a voltage transformer;
[0013] Among them, the first end of the current transformer is electrically connected to the AC bus, and the second end is electrically connected to the second end of the controller, for measuring the current data of the AC bus; the first end of the voltage transformer is connected to the AC bus, the second end is grounded, and the third end is electrically connected to the second end of the controller, for measuring the voltage data of the AC bus.
[0014] In one embodiment, the AC filter bank includes three AC filters;
[0015] The first end of each AC filter is electrically connected to the second end of one circuit breaker, the second end of each AC filter is grounded, and the second end of each circuit breaker is electrically connected to one AC busbar.
[0016] In one embodiment, the AC filter bank includes an AC filter;
[0017] The first end of the AC filter is electrically connected to the second end of the circuit breaker, the second end of the AC filter is grounded, and the first end of the circuit breaker is electrically connected to the three AC busbars respectively.
[0018] In a second aspect, the present application provides a control method for a circuit for suppressing an AC filter closing inrush current, which is applied to a controller included in the circuit for suppressing an AC filter closing inrush current described in any of the above embodiments, including:
[0019] Control the dynamic closing resistor to conduct according to the preset initial value;
[0020] When the conduction time of the dynamic closing resistance is greater than or equal to the preset time period, a closing instruction is issued to the auxiliary breaker of the circuit breaker in response to the closing request to instruct the circuit breaker to perform a closing operation.
[0021] In one embodiment, controlling the dynamic closing resistor to be turned on according to a preset initial value includes:
[0022] A closing command is issued to the main break of the circuit breaker, and an opening command is issued to the auxiliary break of the circuit breaker, so that the dynamic closing resistor is turned on according to a preset initial value.
[0023] In a third aspect, the present application provides a converter station, comprising the AC filter closing inrush current suppression circuit according to any one of the above embodiments.
[0024] In a fourth aspect, the present application provides a control device for a circuit for suppressing a closing inrush current of an AC filter, comprising:
[0025] The resistance conduction module is used to control the dynamic closing resistance to conduct according to the preset initial value;
[0026] The closing indication module is used to respond to the closing request and issue a closing instruction to the auxiliary breaker of the circuit breaker to instruct the circuit breaker to perform the closing operation when the conduction time of the dynamic closing resistance is greater than or equal to the preset time period.
[0027] In a fifth aspect, the present application provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:
[0028] Control the dynamic closing resistor to conduct according to the preset initial value;
[0029] When the conduction time of the dynamic closing resistance is greater than or equal to the preset time period, a closing instruction is issued to the auxiliary breaker of the circuit breaker in response to the closing request to instruct the circuit breaker to perform a closing operation.
[0030] In a sixth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the following steps are implemented:
[0031] Control the dynamic closing resistor to conduct according to the preset initial value;
[0032] When the conduction time of the dynamic closing resistance is greater than or equal to the preset time period, a closing instruction is issued to the auxiliary breaker of the circuit breaker in response to the closing request to instruct the circuit breaker to perform a closing operation.
[0033] The above-mentioned AC filter closing inrush current suppression circuit and control method, converter station, control device and storage medium, the circuit includes a circuit breaker, an AC filter group and a controller; wherein the first end of the circuit breaker is electrically connected to the AC bus, the second end of the circuit breaker is connected to the AC filter group, the circuit breaker is used to control the on and off between the AC filter and the AC bus, one end of the AC bus in the extension direction is electrically connected to the converter transformer, and the other end is connected to the power product, that is, the AC side of the converter transformer is electrically connected to the AC bus; the first end of the AC filter group is electrically connected to the second end of the circuit breaker, and the second end of the AC filter group is grounded, and is used to compensate for the reactive power on the AC side of the converter transformer and filter the reactive power generated by the converter transformer. Harmonics; the first end of the controller is electrically connected to the switch component in the circuit breaker, and is used to send a closing instruction or an opening instruction to the switch component to instruct the switch component to turn on or off; wherein, the circuit breaker includes a dynamic closing resistor and a capacitor connected in parallel with the switch component. The setting of the dynamic closing resistor can not only suppress the closing inrush current generated by the AC filter group when the dynamic closing resistor is put into the circuit, but also reduce the closing inrush current generated when the dynamic closing resistor is removed from the circuit by dynamically reducing the resistance value of the dynamic closing resistor. It also avoids the problem of the related technology that, during phase selection closing, the circuit cannot be accurately closed at the optimal position due to the pre-breakdown characteristics of the fracture and the dispersion of the mechanism action, thereby improving the suppression effect of the closing inrush current. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0035] Figure 1 Schematic diagram of a circuit for suppressing closing inrush current of an AC filter in one embodiment;
[0036] Figure 2 A schematic structural diagram of a circuit for suppressing closing inrush current of an AC filter in another embodiment;
[0037] Figure 3 Schematic diagram of the structure of a circuit for suppressing closing inrush current of an AC filter in another embodiment;
[0038] Figure 4 A schematic structural diagram of a circuit for suppressing closing inrush current of an AC filter in yet another embodiment;
[0039] Figure 5 1 is a flow chart of a method for controlling a circuit for suppressing closing inrush current of an AC filter in one embodiment;
[0040] Figure 6 This is a simulation waveform diagram of a circuit breaker when closing without adding a closing resistor in one embodiment;
[0041] Figure 7 A simulation waveform diagram of a circuit breaker when closing with a fixed closing resistor in parallel in one embodiment;
[0042] Figure 8 A simulation waveform diagram of a circuit breaker when a dynamic closing resistor is connected in parallel to the circuit breaker in one embodiment;
[0043] Figure 9 A simulation waveform diagram of a circuit breaker using a split-phase closing technology in one embodiment;
[0044] Figure 10 A simulation waveform diagram of a parallel dynamic resistor using an AC filter circuit breaker in one embodiment;
[0045] Figure 11 A structural block diagram of a control device for a circuit for suppressing closing inrush current of an AC filter in one embodiment;
[0046] Figure 12 FIG. 1 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION
[0047] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.
[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.
[0049] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intervening element. In addition, the "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc., if there is transmission of electrical signals or data between the connected objects.
[0050] As used herein, the singular forms "a", "an", and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include", "comprising", "having", etc. specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.
[0051] As mentioned in the background, existing methods for suppressing the closing inrush current of AC filters suffer from poor suppression effectiveness. The inventors have discovered that this problem arises because, in ultra-high voltage direct current (UHVDC) transmission projects, AC filters are primarily used to filter harmonics on the AC side to improve power quality, enhance system stability, and provide the required reactive power for commutation. In actual operation, AC filters must be frequently switched on and off according to the system's reactive power and filtering needs. When the AC filter circuit breaker is switched on at different phase points, severe transient high-frequency closing inrush currents and overvoltages are generated, causing severe insulation shock to the internal components of the AC filter and the circuit breaker itself, resulting in reduced electrical life and easily causing burnout and welding of the AC filter circuit breaker contacts. Furthermore, transient inrush currents and overvoltages can also cause frequent malfunctions of the AC filter's capacitor unbalance protection and lightning arrester. In severe cases, switching the AC filter on and off can cause harmonic instability, bus voltage distortion, and ultimately commutation failure. In the related art, methods for suppressing the closing inrush current of an AC filter circuit breaker include: using a series reactor, using a closing resistor to switch a switch, and using a thyristor to switch a capacitor. Although the use of series reactors can limit the current generated when the AC filter circuit breaker is switched on at different phase points, it cannot change the mechanical dispersion of the AC filter circuit breaker. Therefore, after the use of series reactors, the AC filter circuit breaker will still produce serious transient high-frequency closing inrush current and overvoltage when it is frequently switched on and off, and the suppression effect is not obvious. When using closing resistor switching switches, since the closing resistor switching switches are closed and opened mechanically, after the closing resistor switching switches are frequently switched on and off, as some of their internal structures wear and age, their closing time is prolonged, resulting in large dispersion in their closing time, causing the AC filter circuit breaker to no longer be able to close at the optimal closing time, resulting in large dispersion in the actual conduction time of the AC filter circuit breaker, poor suppression effect on the inrush current during closing, and unsatisfactory suppression effect. Although thyristor switching capacitor technology can effectively reduce the transient high-frequency closing inrush current and overvoltage phenomena that occur during the closing process of the filter circuit breaker, the device is expensive and consumes large power, making it impractical for large-scale, long-line power grids.
[0052] Based on the above reasons, the present invention provides a circuit for suppressing the closing inrush current of an AC filter, aiming to improve the suppression effect of the closing inrush current.
[0053] In one embodiment, Figure 1 As shown, a circuit 1 for suppressing closing inrush current of an AC filter is provided, comprising a circuit breaker 11, an AC filter group 12 and a controller 13;
[0054] Among them, the first end of the circuit breaker 11 is electrically connected to the AC bus 14, and the second end of the circuit breaker 11 is electrically connected to the AC filter group 12. The circuit breaker 11 is used to control the on and off between the AC filter group and the AC bus 14; one end of the AC bus 14 in the extension direction is electrically connected to the converter transformer, and the other end is electrically connected to the electrical product, that is, the AC side of the converter transformer is electrically connected to the AC bus 14.
[0055] A first end of the AC filter group 12 is electrically connected to a second end of the circuit breaker 11 , and a second end of the AC filter group 12 is grounded. The AC filter group 12 is used to compensate for reactive power on the AC side of the converter transformer and filter harmonics generated by the converter transformer.
[0056] The first end of the controller 13 is electrically connected to the switch component 111 in the circuit breaker 11, and is used to send a closing instruction or an opening instruction to the switch component 111 to instruct the switch component 111 to turn on or off; wherein, the circuit breaker 11 also includes a dynamic closing resistor 112 and a capacitor 113 connected in parallel with the switch component 111.
[0057] It will be appreciated that dynamic closing resistor 112 is a current-limiting resistor used to suppress the closing inrush current generated by AC filter bank 12 when circuit breaker 11 is closed, and capacitor 113 is used to suppress overvoltage generated when circuit breaker 11 is opened. Circuit breaker 11 controls whether AC filter bank 12 is electrically connected to or disconnected from AC bus 14 by closing switch assembly 111.
[0058] It should be noted that the principle of closing inrush current is that the AC side of the converter transformer in the converter station typically uses a dual-tuned filter, and the dual-tuned filter can be simplified to a combination of two single-tuned filters. The equivalent circuit of the single-tuned filter consists of a loop composed of RLC elements connected in series. When the circuit breaker is closed, the residual charge of the AC filter group is generally discharged. If the circuit breaker is closed at the voltage peak, a large closing inrush current will be generated, which may cause bus voltage distortion, and then trigger commutation failure and DC system lockout. The effect of the closing resistor setting on suppressing closing inrush current can be divided into two stages: closing resistor activation and deactivation. Compared with the AC filter without the closing resistor, the activation of the closing resistor can significantly reduce the transient inrush current. When the closing resistor is activated, the closing inrush current is greatly suppressed. When the closing resistor is removed, the AC filter has already stored a certain amount of energy. At this point, the resistance value in the AC filter group circuit is approximately zero, so only the capacitor components are considered. Therefore, the removal of the closing resistor can be considered as the power supply charging the capacitor, and the charging time is extremely short. The greater the voltage difference between the power supply and the capacitor, the greater the inrush current generated. The smaller the resistance of the closing resistor at the moment of removal, the smaller the inrush current. RLC components include resistors, inductors, and capacitors.
[0059] The above-mentioned AC filter closing inrush current suppression circuit includes a circuit breaker 11, an AC filter group 12 and a controller 13; wherein the second end of the circuit breaker 11 is electrically connected to the AC filter group 12, and the circuit breaker 11 is used to control the on and off between the AC filter group and the AC bus 14; one end of the AC bus 14 in the extension direction is electrically connected to the converter transformer, and the other end is electrically connected to the electrical product, that is, the AC side of the converter transformer is electrically connected to the AC bus 14; the first end of the AC filter group 12 is electrically connected to the second end of the circuit breaker 11, and the second end of the AC filter group 12 is grounded, and is used to compensate for the reactive power on the AC side of the converter transformer and filter the harmonics generated by the converter transformer; the first end of the controller 13 is connected to the switch component in the circuit breaker 11 111 is electrically connected and used to send a closing instruction or an opening instruction to the switch component 111 to instruct the switch component 111 to be turned on or off; wherein, the circuit breaker 11 includes a dynamic closing resistor 112 and a capacitor 113 connected in parallel with the switch component 111. The setting of the dynamic closing resistor 112 can not only suppress the closing inrush current generated by the AC filter group 12 when the dynamic closing resistor 112 is put into the circuit, but also reduce the closing inrush current generated when the dynamic closing resistor 112 is withdrawn from the circuit by dynamically reducing the resistance value of the dynamic closing resistor 112. It also avoids the problem in the related technology that, during phase selection closing, the circuit breaker cannot accurately close at the optimal position due to the pre-breakdown characteristics of the fracture and the dispersion of the mechanism action, thereby improving the suppression effect of the closing inrush current.
[0060] In one embodiment, continue to refer to Figure 1, the switch assembly 111 includes a main break 1111 and an auxiliary break 1112;
[0061] Among them, the first end of the auxiliary break 1112 is electrically connected to the AC bus 14, the second end of the auxiliary break 1112 is electrically connected to the first end of the main break 1111, and the second end of the main break 1111 is electrically connected to the AC filter group 12; the main break 1111 is used to coordinate with the auxiliary break 1112 to control the on and off between the AC filter group 12 and the AC bus 14.
[0062] It is understood that main break 1111 is the primary conductive path of circuit breaker 11, responsible for carrying the rated current of the circuit when closed. During opening, main break 1111 rapidly opens, severing the current path and preventing the arc from continuing to burn. Auxiliary break 1112 is connected in parallel with dynamic closing resistor 112. Closing auxiliary break 1112 at the initial closing stage allows dynamic closing resistor 112 to enter the circuit, limiting the closing inrush current and overvoltage generated by AC filter bank 12 at the moment of closing. During the opening process, the delayed opening of auxiliary break 1112 reduces the energy of the arc at main break 1111, protecting the main contacts.
[0063] In this embodiment, the circuit breaker 11 is provided with a main break 1111 and an auxiliary break 1112. The main break 1111 is responsible for switching large currents, and the auxiliary break 1112 shares the arc energy, which can extend the life of the circuit breaker 11. The auxiliary break 1112 introduces a dynamic closing resistor 112 to suppress the closing inrush current. In addition, the main break 1111 and the auxiliary break 1112 are operated in stages to avoid mechanical shock and improve the stability of the system.
[0064] In one embodiment, continue to refer to Figure 1 The two ends of the dynamic closing resistor 112 are electrically connected to the two ends of the auxiliary breaker 1112, and the two ends of the capacitor 113 are electrically connected to the two ends of the main breaker 1111.
[0065] The initial value of the dynamic closing resistor 112 in the circuit can be 400Ω, and the resistance rule can be as follows: Ω changes, t is time, and the changing rule can be determined based on the closing simulation experiment of the AC side of the converter transformer and the circuit breaker 11.
[0066] It can be understood that dynamic resistance refers to the transient response characteristics of a device (such as a diode or transistor) or circuit to current changes under specific operating conditions. When circuit breaker 11 opens, the sudden termination of current causes high voltage to be generated in the inductor. Connecting capacitor 113 in parallel with main breaker 1111 absorbs the energy released by the inductor, slowing the rate of voltage rise and preventing breakdown of the equipment insulation. Replacing the fixed closing resistor with a dynamic closing resistor 112 in parallel with auxiliary breaker 1112 effectively reduces the closing inrush current during closing (gradually reducing the resistance of dynamic closing resistor 112) when main breaker 1111 is closed and AC filter group 12 is put into the circuit. This also reduces the closing inrush current caused by closing auxiliary breaker 1112, thereby improving the suppression of the closing inrush current.
[0067] In one embodiment, Figure 2 As shown, the AC filter closing inrush current suppression circuit also includes a current transformer 21 and a voltage transformer 22;
[0068] Among them, the first end of the current transformer 21 is electrically connected to the AC bus 14, and the second end is electrically connected to the second end of the controller 13, for measuring the current data of the AC bus 14; the first end of the voltage transformer 22 is connected to the AC bus 14, the second end is grounded, and the third end is electrically connected to the second end of the controller 13, for measuring the voltage data of the AC bus 14.
[0069] Among them, the current transformer 21 is a device used to measure AC current. By converting high current into a small, manageable current, it protects measuring equipment and instruments. Its operating principle is based on electromagnetic induction: the current flowing through the main current coil generates a proportional small current for use by other equipment. The voltage transformer 22, also known as a voltage converter, is used to measure AC voltage. Its function is to convert high voltage into a lower, safely measurable voltage. It is commonly used in power system monitoring and control to ensure that measuring equipment operates within a safe voltage range. It also works based on the principle of electromagnetic induction.
[0070] It should be noted that the controller 13 obtains the current data of the AC bus 14 collected by the current transformer 21 and the voltage data collected by the voltage transformer 22. Based on the current and voltage data, the controller 13 initiates a closing command in response to requests for harmonic filtering and reactive power compensation. This allows the AC filter to be put into the circuit for filtering in a timely manner.
[0071] In one embodiment, Figure 3 As shown, the AC filter group 12 includes three AC filters;
[0072] The first end of each AC filter is electrically connected to the second end of a circuit breaker 11 , the second end of each AC filter is grounded, and the second end of each circuit breaker 11 is electrically connected to an AC busbar 14 .
[0073] It should be noted that the specific topology of the AC filter is not particularly limited, as long as it is a circuit topology that can filter out harmonics and compensate for reactive power.
[0074] It is understandable that the three AC busbars 14 (as shown in the attached Figure 3 The AC busbars 1, 2 and 3 in the figure are used to transmit the AC power output by the three-phase coils on the AC side of the converter transformer, and each AC filter is used to filter the harmonics generated by the AC side of one phase of the converter transformer, and each circuit breaker 11 (as shown in the attached figure) is used to transmit the AC power output by the three-phase coils on the AC side of the converter transformer. Figure 3 The function of the circuit breaker 1, circuit breaker 2 and circuit breaker 3 is to control the on-off between the corresponding AC filter and the AC bus 14 to suppress the closing inrush current when closing. Each circuit breaker 11 adopts a single-phase double-break circuit breaker 11. Figure 3 AC filter 1, AC filter 2 and AC filter 3 in the system are connected to three AC busbars 14 through three circuit breakers 11 respectively, which means that each filter processes the harmonics of one phase independently, which helps to balance the three-phase system and reduce mutual interference.
[0075] In one embodiment, Figure 4 As shown, the AC filter group 12 includes an AC filter;
[0076] The first end of the AC filter is electrically connected to the second end of the circuit breaker 11 , the second end of the AC filter is grounded, and the first end of the circuit breaker 11 is electrically connected to the three AC busbars 14 .
[0077] It should be noted that the specific topology of the AC filter is not particularly limited, as long as it is a circuit topology that can filter out harmonics and compensate for reactive power.
[0078] It is understood that the three AC busbars 14 are respectively used to transmit the AC power output by the three-phase coils on the AC side of the converter transformer. The AC filter centrally handles filtering and reactive power compensation of the three-phase AC power. The circuit breaker 11 controls the connection and disconnection of the entire AC filter. Circuit breaker 11 adopts a three-phase double-break circuit breaker 11. Because the dynamic closing resistor is set to suppress the closing inrush current, it is no longer necessary to suppress the closing inrush current through phase selection closing. Therefore, the closing inrush current can still be suppressed by controlling the connection and disconnection of the entire AC filter through a single circuit breaker 11, which reduces the complexity of the circuit structure, operation complexity, and equipment cost.
[0079] In one embodiment, Figure 5 As shown, a control method for a circuit for suppressing closing inrush current of an AC filter is provided, which is applied to a controller included in the circuit for suppressing closing inrush current of an AC filter described in any one of the above embodiments. The method comprises:
[0080] Step S502 , controlling the dynamic closing resistor to be turned on according to a preset initial value.
[0081] The initial value may be the initial resistance value of the dynamic closing resistor when it is connected to the circuit, and is determined by the limitation of the DC transmission system on the maximum current of the AC filter.
[0082] Optionally, the controller detects the current current data and voltage data of the current AC bus, and then compares them with the pre-set system requirements for filtering harmonics and compensating reactive power to determine whether a closing operation is required at this time. If it is determined that a closing operation is required, the controller sends an opening command to the auxiliary break of the circuit breaker and a closing command to the main break to control the dynamic closing resistor to be turned on according to a preset initial value, so that the dynamic closing resistor is put into use to suppress the closing inrush current generated by the AC filter group.
[0083] Step S504: When the conduction time of the dynamic closing resistance is greater than or equal to the preset time period, respond to the closing request and send a closing instruction to the auxiliary breaker of the circuit breaker to instruct the circuit breaker to perform the closing operation.
[0084] The preset time period may be determined by multiple simulation experiments of a circuit for suppressing the closing inrush current of the AC filter.
[0085] Optionally, after the auxiliary breaker is opened and connected to the dynamic closing resistor, the dynamic closing resistor is kept connected for a period of time. When the conduction time is greater than or equal to a preset time period, such as the conduction time is greater than or equal to 10ms, the resistance of the dynamic closing resistor changes according to the element and the change law, and the resistance is reduced. The controller responds to the closing request and sends a closing instruction to the auxiliary breaker of the circuit breaker, so that the dynamic closing resistor exits the circuit. However, since the resistance of the dynamic closing resistor becomes smaller, the closing inrush current when the dynamic closing resistor exits is suppressed, so as to complete the closing operation of the two breaks of the circuit breaker, and the AC filter group is put into the circuit.
[0086] In this embodiment, when the circuit breaker needs to be closed, the initial value of the dynamic closing resistor that meets the closing inrush current suppression requirements is put into the circuit to suppress the closing inrush current generated by the AC filter group when the main breaker is closed. The dynamic closing resistor is turned on for a period of time, so that the resistance value of the dynamic closing resistor becomes smaller, so that the auxiliary breaker is closed. When the dynamic closing resistor exits the circuit, the closing inrush current generated again by the AC filter group is suppressed, thereby improving the closing inrush current suppression effect.
[0087] In one embodiment, step S502 controls the dynamic closing resistor to be turned on according to a preset initial value, including:
[0088] A closing command is issued to the main break of the circuit breaker, and an opening command is issued to the auxiliary break of the circuit breaker, so that the dynamic closing resistor is turned on according to the preset initial value.
[0089] Optionally, the controller sends a closing command to the main break of the circuit breaker and an opening command to the auxiliary break of the circuit breaker, so that the auxiliary break is closed, and the dynamic closing resistor connected in parallel at both ends of the auxiliary break is turned on according to a preset initial value, thereby suppressing the closing inrush current generated by the AC filter group when the main break is closed.
[0090] In this embodiment, when the circuit breaker needs to be closed, the initial value of the dynamic closing resistor that meets the closing inrush current suppression requirement is input into the circuit to suppress the closing inrush current generated by the AC filter group when the main breaker is closed.
[0091] In one embodiment, simulation operations were performed for three situations: closing the circuit breaker without adding a closing resistor, closing the circuit breaker in parallel with a fixed closing resistor, and closing the circuit breaker in parallel with a dynamic closing resistor. Figure 6 This is the waveform diagram when the circuit breaker is closed without adding closing resistance. Figure 7 This is the waveform diagram when the circuit breaker is closed in parallel with the fixed closing resistor. Figure 8 It is the waveform diagram when the circuit breaker is closed in parallel with the dynamic closing resistor.
[0092] according to Figure 6 、 Figure 7 and Figure 8 It can be seen that when the circuit breaker is closed at t = 0.03s, the maximum closing inrush current in the three cases is 1.235kA, 0.738kA, and 0.621kA, respectively. This shows that the dynamic closing resistor in parallel with the circuit breaker can effectively suppress the closing inrush current.
[0093] In one embodiment, the phase-splitting closing technology is used to close each phase A, B, and C at the time when the voltage crosses zero, and the following is obtained: Figure 9 The simulation results show that the closing times of the three-phase circuit breakers are: 0.0241s for phase A, 0.0308s for phase B, and 0.0375s for phase C. The closing inrush current of phase A reaches its maximum value of 0.611kA at 0.0341s, 0.628kA for phase B at 0.0408s, and 0.605kA for phase C at 0.0475s.
[0094] In addition, the technology of connecting the AC filter circuit breaker in parallel with the dynamic resistor is adopted. When the bus voltage reaches the peak value, the circuit breaker is closed to obtain the following Figure 10 The simulation results shown in the figure show that the closing time is 0.0291s, and the closing inrush current reaches its maximum value of 0.632kA at 0.0351s. Compared with phase-by-phase closing, the circuit breaker with parallel dynamic resistors can effectively suppress the closing inrush current even when closing at random times.
[0095] In one embodiment, a converter station is provided, comprising the AC filter closing inrush current suppression circuit described in any one of the above embodiments.
[0096] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.
[0097] Based on the same inventive concept, embodiments of the present application further provide a control device for an AC filter closing inrush current suppression circuit, for implementing the aforementioned control method for an AC filter closing inrush current suppression circuit. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more embodiments of the control device for an AC filter closing inrush current suppression circuit provided below can be found in the aforementioned limitations of the control method for an AC filter closing inrush current suppression circuit, and will not be further elaborated here.
[0098] In one embodiment, Figure 11 As shown, a control device 11 for suppressing the closing inrush current of an AC filter is provided, comprising: a resistance conduction module 1101 and a closing indication module 1102, wherein:
[0099] The resistance conduction module 1101 is used to control the dynamic closing resistor to conduct according to a preset initial value.
[0100] The closing instruction module 1102 is used to respond to the closing request and issue a closing instruction to the auxiliary breaker of the circuit breaker to instruct the circuit breaker to perform the closing operation when the conduction time of the dynamic closing resistance is greater than or equal to the preset time period.
[0101] Furthermore, in one embodiment, the resistance conducting module 1101 is further configured to issue a closing instruction to the main breaker of the circuit breaker and an opening instruction to the auxiliary breaker of the circuit breaker, so that the dynamic closing resistor is conducted according to a preset initial value.
[0102] Each module in the control device for the AC filter closing inrush current suppression circuit described above can be implemented in whole or in part through software, hardware, or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in hardware form, or can be stored in a computer device memory in software form, so that the processor can call and execute the corresponding operations of each module.
[0103] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as follows: Figure 12 As shown. The computer device includes a processor, a memory, and a network interface connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The database of the computer device is used to store data such as current data, voltage data, and the conduction time of the dynamic closing resistance. The network interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, a control method for a circuit for suppressing closing inrush current of an AC filter is implemented.
[0104] Those skilled in the art will understand that Figure 12 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.
[0105] In one embodiment, a computer device is further provided, including a memory and a processor. The memory stores a computer program, and the processor implements the steps in the above method embodiments when executing the computer program.
[0106] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.
[0107] In one embodiment, a computer program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.
[0108] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the above-mentioned embodiments. In particular, any reference to memory, database, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processors involved in the various embodiments provided herein may be, but are not limited to, general-purpose processors, central processing units (CPUs), graphics processing units (GPUs), digital signal processors (DSPs), programmable logic devices (PLDs), data processing logic devices based on quantum computing, and the like.
[0109] Throughout this specification, references to terms such as "some embodiments," "other embodiments," and "desired embodiments" indicate that a particular feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Although these terms are used interchangeably throughout this specification, they do not necessarily refer to the same embodiment or example.
[0110] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0111] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.
Claims
1. A circuit for suppressing inrush current during closing of an AC filter, characterized in that: include: a circuit breaker, wherein a first end of the circuit breaker is electrically connected to the AC bus; an AC filter group, wherein a first end of the AC filter group is electrically connected to a second end of the circuit breaker, and a second end of the AC filter group is grounded; a controller, wherein a first end of the controller is electrically connected to a switch assembly in the circuit breaker and is configured to send a closing instruction or an opening instruction to the switch assembly; Wherein, the circuit breaker includes a dynamic closing resistor and a capacitor connected in parallel with the switch component.
2. The AC filter closing inrush current suppression circuit according to claim 1, characterized in that: The switch assembly includes a main break and an auxiliary break; Among them, the first end of the auxiliary break is electrically connected to the AC bus, the second end of the auxiliary break is electrically connected to the first end of the main break, and the second end of the main break is electrically connected to the AC filter group; the main break is used to coordinate with the auxiliary break to control the on and off between the AC filter group and the AC bus.
3. The AC filter closing inrush current suppression circuit according to claim 2, characterized in that: The two ends of the dynamic closing resistor are electrically connected to the two ends of the auxiliary break, and the two ends of the capacitor are electrically connected to the two ends of the main break.
4. The AC filter closing inrush current suppression circuit according to claim 1, characterized in that: The resistance of the dynamic closing resistor is Ω; t represents time.
5. The AC filter closing inrush current suppression circuit according to claim 1, characterized in that: Also includes current transformers and voltage transformers; Among them, the first end of the current transformer is electrically connected to the AC bus, and the second end is electrically connected to the second end of the controller, for measuring the current data of the AC bus; the first end of the voltage transformer is connected to the AC bus, the second end is grounded, and the third end is electrically connected to the second end of the controller, for measuring the voltage data of the AC bus.
6. The AC filter closing inrush current suppression circuit according to claim 1, characterized in that: The AC filter group includes three AC filters; The first end of each AC filter is electrically connected to the second end of one circuit breaker, the second end of each AC filter is grounded, and the second end of each circuit breaker is electrically connected to one AC busbar.
7. The AC filter closing inrush current suppression circuit according to claim 1, characterized in that: The AC filter group includes an AC filter; The first end of the AC filter is electrically connected to the second end of the circuit breaker, the second end of the AC filter is grounded, and the first end of the circuit breaker is electrically connected to the three AC busbars respectively.
8. A control method for a circuit for suppressing closing inrush current of an AC filter, characterized in that: A controller comprising a circuit for suppressing closing inrush current of an AC filter according to any one of claims 1 to 7, comprising: Control the dynamic closing resistor to conduct according to the preset initial value; When the conduction time of the dynamic closing resistance is greater than or equal to the preset time period, a closing instruction is issued to the auxiliary breaker of the circuit breaker in response to the closing request to instruct the circuit breaker to perform a closing operation.
9. The control method for the AC filter closing inrush current suppression circuit according to claim 8, characterized in that: The controlling the dynamic closing resistor to be turned on according to a preset initial value includes: A closing command is issued to the main break of the circuit breaker, and an opening command is issued to the auxiliary break of the circuit breaker, so that the dynamic closing resistor is turned on according to a preset initial value.
10. A converter station, characterized in that: The invention comprises a circuit for suppressing closing inrush current of an AC filter according to any one of claims 1 to 7.