A converter transformer excitation inrush suppressing device

Abstract

The application discloses a converter transformer excitation inrush current suppression device, which is applied to a converter transformer circuit with a voltage level of 550kV. The operation of a quick disconnecting switch in a suppression module is controlled by a control module, so that the time of resistance input into the converter transformer circuit is controlled. Since the response time of the control module is generally 8ms-10ms, the quick disconnecting switch can complete the operation in about 30ms (dispersion is ±2ms). Therefore, the resistance input time of the converter transformer excitation inrush current suppression device disclosed by the application can reach 40ms. The resistance input time is longer than that of a closing resistance excitation inrush current suppression device, and is much smaller than that of a starting resistance excitation inrush current suppression device. The excitation inrush current suppression effect is better, the requirement for the resistance heat capacity is reduced, and the manufacturing cost of the excitation inrush current suppression device is reduced.

Description

Technical Field

[0001] This invention relates to the field of DC power transmission technology, and in particular to a converter transformer inrush current suppression device. Background Technology

[0002] The converter transformer is a core component of the ultra-high voltage DC converter station. When the unloaded converter transformer is put into operation, the core magnetic flux is easily saturated, which may generate a huge inrush current, causing the protection device to malfunction and preventing the transformer from working normally. Therefore, certain measures need to be taken to suppress the inrush current of the converter transformer.

[0003] Existing DC transmission projects typically use inrush current suppression devices with closing resistors, phase-selective closing resistors, or starting resistors in converter stations to suppress inrush current in converter transformers. These devices generally effectively suppress inrush current during transformer closing, but several problems exist. Among these, inrush current suppression devices using phase-selective closing resistors have a relatively low success rate. Furthermore, in inrush current suppression devices using circuit breakers with closing resistors do not have specific national or industry standards regarding the size and timing of the closing resistor. Current experience suggests that an opening time of 8ms to 11ms is sufficient to suppress inrush current. However, in practical applications, even after adding closing resistors according to conventional requirements, situations still arise where insufficient closing time leads to excessively large inrush currents. The solution is usually to modify the circuit breaker mechanism to extend the closing resistor engagement time and thus suppress inrush current. However, due to the limitations of the circuit breaker mechanism, the closing resistor is controlled as an integral part of the circuit breaker, and the extension of the closing resistor engagement time is limited to a certain range. Even with technical modifications to the circuit breaker, it is difficult to extend the closing resistor engagement time to more than 15ms, resulting in poor inrush current suppression.

[0004] Currently, flexible DC converter stations generally use parallel switching with starting resistors to suppress the charging current of the flexible DC valves. If an inrush current suppression device using parallel switching with starting resistors is placed on the converter transformer grid side, it can also suppress the inrush current during converter transformer closing, and the effect is better than that of an inrush current suppression device using closing resistors. However, the inrush current suppression device with starting resistors has an open structure, which occupies a large space. Furthermore, since the starting resistor is typically engaged for more than 1 minute, it requires a resistance value of over 5000Ω, thus requiring a high thermal capacity and increasing the manufacturing cost of the inrush current suppression device. Summary of the Invention

[0005] This invention provides a converter transformer inrush current suppression device, which solves the technical problems of poor inrush current suppression effect of the closing resistor inrush current suppression device and high manufacturing cost of the starting resistor inrush current suppression device in the prior art.

[0006] This invention provides a converter transformer inrush current suppression device, which is applied to a converter transformer circuit with a voltage level of 550kV. The device includes a control module and a suppression module.

[0007] The suppression module is connected between the combined electrical appliance and the converter transformer in the converter transformer circuit;

[0008] The control module is connected to the converter transformer, the combined electrical equipment, and the suppression module;

[0009] The control module is used to send action commands to the combined electrical equipment and the suppression module when it receives a status request from the converter transformer and meets preset conditions.

[0010] The suppression module includes a fast disconnect switch, a grounding switch, and a resistor;

[0011] One end of the fast disconnect switch is connected to one end of the grounding switch to form a first branch; the other end of the grounding switch is connected to ground; the first branch is connected in parallel with the resistor;

[0012] The suppression module is used to execute the actions of the fast disconnect switch and the grounding switch in response to the action command.

[0013] Optionally, the control module includes a detection submodule and a control submodule;

[0014] The detection submodule is used to determine whether the preset conditions are met based on the received status request; if so, it sends a control command to the control submodule; otherwise, it rejects the status request.

[0015] The control submodule is used to respond to the control command and send action commands to the combined electrical appliance and the suppression module.

[0016] Optionally, the request includes a charging request and a shutdown request; the action command includes a closing command and a opening command.

[0017] Optionally, the detection submodule is specifically used for:

[0018] When the charging request is received, the time interval between the request time of the charging request and the obtained historical charging end time is calculated;

[0019] If the time interval is less than a preset time threshold, the charging request is rejected.

[0020] If the time interval is greater than or equal to a preset time threshold, the number of charging times is increased by a preset value, and it is determined whether the current number of charging times is greater than the preset number threshold.

[0021] If the current number of charging cycles exceeds the preset number threshold, and the measured resistance temperature is higher than the measured ambient temperature, then the number of charging cycles is reset when the resistance temperature drops to the ambient temperature.

[0022] If the current number of charging cycles is greater than the preset number threshold, and the measured resistance temperature is lower than or equal to the measured ambient temperature, then in response to the charging request, a first control command is sent to the control submodule, and when the circuit breaker of the combined electrical appliance is detected to be closed and the converter transformer has a current signal, a second control command is sent to the control submodule.

[0023] If the current number of charging attempts is less than or equal to the preset number of attempts, then in response to the charging request, a first control command is sent to the control submodule, and when the circuit breaker of the combined electrical appliance is detected to be closed and the converter transformer has a current signal, a second control command is sent to the control submodule.

[0024] Optionally, the control submodule is specifically used for:

[0025] In response to the first control command, closing commands are sequentially sent to the second disconnecting switch, the first disconnecting switch, and the circuit breaker of the combined electrical appliance;

[0026] In response to the second control command, a closing command is sent to the fast disconnect switch.

[0027] Optionally, the detection submodule is further configured to:

[0028] When the exit operation request is received, a third control command is sent to the control submodule, and when the second disconnecting switch of the combined electrical appliance is detected to have been opened, a fourth control command is sent to the control submodule.

[0029] Optionally, the control submodule is further configured to:

[0030] In response to the first control command, tripping commands are sent sequentially to the circuit breaker, the first disconnecting switch, and the second disconnecting switch of the combined electrical appliance;

[0031] In response to the second control command, a tripping command is sent to the fast disconnecting switch, and a closing command is sent to the grounding switch.

[0032] Optionally, the operating mechanism of the fast disconnect switch is a hydraulic operating mechanism, which is used to perform the corresponding action after determining the action duration according to the received action command.

[0033] Optionally, the resistance value of the resistor is greater than or equal to 1500Ω.

[0034] Optionally, the exterior of the suppression module is a canister-like structure.

[0035] As can be seen from the above technical solutions, the present invention has the following advantages:

[0036] This invention provides a converter transformer inrush current suppression device, applied to a 550kV converter transformer circuit. The control module controls the action of a fast disconnect switch in the suppression module, thereby controlling the time it takes for the resistor to be engaged in the converter transformer circuit. Since the response time of current control modules is generally 8ms to 10ms, and the fast disconnect switch can complete its action in approximately 30ms (with a dispersion of ±2ms), the resistor engagement time of the converter transformer inrush current suppression device provided by this invention can reach 40ms. This engagement time is longer than that of a closing resistor inrush current suppression device, and much shorter than that of a starting resistor inrush current suppression device. This not only results in better inrush current suppression but also reduces the requirement for resistor heat capacity, thus lowering the manufacturing cost of the inrush current suppression device. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of a converter transformer inrush current suppression device provided in Embodiment 1 of the present invention;

[0039] Figure 2 This is a schematic diagram of the structure of a converter transformer inrush current suppression device provided in Embodiment 2 of the present invention;

[0040] Figure 3 This is a schematic diagram of the hydraulic operating mechanism provided in Embodiment 2 of the present invention;

[0041] Figure 4 This is a schematic diagram of the external structure of the suppression module provided in Embodiment 2 of the present invention. Detailed Implementation

[0042] This invention provides a converter transformer inrush current suppression device to solve the technical problems of poor inrush current suppression effect of closing resistor inrush current suppression device and high manufacturing cost of starting resistor inrush current suppression device in the prior art.

[0043] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0044] Please see Figure 1 , Figure 1 This is a schematic diagram of a converter transformer inrush current suppression device provided in Embodiment 1 of the present invention, where E represents the AC power supply.

[0045] The present invention provides a converter transformer inrush current suppression device, which is applied to a converter transformer circuit with a voltage level of 550kV, and includes a control module 101 and a suppression module 102.

[0046] The suppression module 102 is connected between the combined electrical appliance C and the converter transformer T in the converter transformer circuit.

[0047] The control module 101 is connected to the converter transformer T, the combined electrical appliance C, and the suppression module 102.

[0048] The control module 101 is used to send an action command to the combined electrical equipment and the suppression module 102 when it receives a status request from the converter transformer and meets the preset conditions.

[0049] The suppression module 102 includes a fast disconnect switch DS1, a grounding switch ES1, and a resistor R1.

[0050] One end of the fast disconnect switch DS1 is connected to one end of the grounding switch ES1 to form the first branch; the other end of the grounding switch ES1 is connected to ground; the first branch is connected in parallel with the resistor R1.

[0051] The suppression module 102 is used to execute the actions of the fast disconnect switch DS1 and the grounding switch ES1 in response to the action command.

[0052] It should be noted that the response time of the current control module is generally 10ms, while the fast disconnect switch DS1 can complete the action in about 30ms (with a dispersion of ±2ms).

[0053] Embodiment 1 of this invention provides a converter transformer inrush current suppression device, applied to a converter transformer circuit with a voltage level of 550kV. The control module controls the action of the fast disconnect switch in the suppression module, thereby controlling the time when the resistor is engaged in the converter transformer circuit. Since the response time of current control modules is generally 10ms, and the fast disconnect switch can complete its action in about 30ms (with a dispersion of ±2ms), the resistor engagement time of the converter transformer inrush current suppression device provided by this invention can reach 40ms. This resistor engagement time is longer than that of the closing resistor inrush current suppression device and much shorter than that of the starting resistor inrush current suppression device. This not only results in better inrush current suppression but also reduces the requirement for resistor heat capacity, thus lowering the manufacturing cost of the inrush current suppression device.

[0054] Please see Figure 2 , Figure 2 This is a schematic diagram of the structure of a converter transformer inrush current suppression device provided in Embodiment 2 of the present invention.

[0055] The present invention provides a converter transformer inrush current suppression device, which is applied to a converter transformer circuit with a voltage level of 550kV. The device includes a control module 201 and a suppression module 202.

[0056] The suppression module 202 is connected between the combined electrical appliance C and the converter transformer T in the converter transformer circuit.

[0057] The control module 201 is connected to the converter transformer T, the combined electrical appliance C, and the suppression module 202.

[0058] It should be noted that, as Figure 2 As shown, E represents the AC power supply, and the combined electrical appliance C is represented by the circuit breaker CB and the first disconnecting switch Q1 and the second disconnecting switch Q2 on both sides. The combined electrical appliance generally also includes a grounding switch, voltage transformer, current transformer, surge arrester, and live display device, etc. This invention is only used to illustrate the logical relationship between the combined electrical appliance and the device of this invention; therefore, in… Figure 2 The combined electrical appliance is simplified to a circuit breaker CB and its two sides, with the first disconnecting switch Q1 and the second disconnecting switch Q2 described below.

[0059] The suppression module 202 includes a fast disconnect switch DS2, a grounding switch ES2, and a resistor R2.

[0060] One end of the fast disconnect switch DS2 is connected to one end of the grounding switch ES2 to form the first branch; the other end of the grounding switch ES2 is connected to ground; the first branch is connected in parallel with the resistor R2.

[0061] The control module 201 includes a detection submodule 2011 and a control submodule 2012.

[0062] The detection submodule 2011 is used to determine whether the preset conditions are met based on the received status request; if so, it sends a control command to the control submodule 2012; otherwise, it rejects the status request.

[0063] The control submodule 2012 is used to respond to control commands and send action commands to the combined electrical appliance C and the suppression module 202.

[0064] The requests include charging requests and exiting the program requests.

[0065] Action commands include closing commands and opening commands.

[0066] It should be noted that the response time of the current control module is generally 10ms, while the fast disconnect switch DS2 can complete the closing in about 30ms (with a dispersion of ±2ms). Therefore, the resistor connection time of the converter transformer inrush current suppression device provided in Embodiment 2 of this invention can reach 40ms. In addition, by adjusting the response time of the control module, the resistor connection time can be extended, provided that the resistor heat capacity meets the requirements, thus achieving adjustable resistor connection time.

[0067] The detection submodule 2011 is specifically used for:

[0068] When a charging request is received, the time interval between the request time and the obtained historical charging end time is calculated.

[0069] If the time interval is less than a preset time threshold, the charging request will be rejected.

[0070] If the time interval is greater than or equal to the preset time threshold, the number of charging times will be increased by the preset value, and it will be determined whether the current number of charging times is greater than the preset number of times threshold.

[0071] If the current number of charging cycles exceeds the preset threshold and the measured resistance temperature is higher than the measured ambient temperature, then the number of charging cycles will be reset when the resistance temperature drops to the ambient temperature.

[0072] If the current number of charging attempts exceeds the preset threshold, and the measured resistance temperature is lower than or equal to the measured ambient temperature, then respond to the charging request and send a first control command to the control submodule 2012. When the circuit breaker CB of the combined electrical appliance C is closed and the converter transformer T has a current signal, send a second control command to the control submodule 2012.

[0073] If the current number of charging attempts is less than or equal to the preset number of attempts, then respond to the charging request and send a first control command to the control submodule 2012. When it is detected that the circuit breaker CB of the combined electrical appliance C is closed and there is a current signal in the converter transformer T, then send a second control command to the control submodule 2012.

[0074] It should be noted that the preset time threshold can be set to 30 minutes, the preset number threshold can be set to 3 times, and the preset value can be set to 1 time.

[0075] The control submodule 2012 is specifically used for:

[0076] In response to the first control command, closing commands are sent sequentially to the second disconnecting switch Q2, the first disconnecting switch Q1, and the circuit breaker CB of the combined electrical appliance C;

[0077] In response to the second control command, a closing command is sent to the fast disconnect switch DS2.

[0078] It should be noted that before the converter transformer is charged, the states of each switch are as follows: the combined electrical circuit breaker CB, the first isolating switch Q1, and the second isolating switch Q2 are in the open state; the fast isolating switch DS2 and the grounding switch ES2 in the converter transformer inrush current suppression device are in the open state. During the converter transformer charging process, the operation logic of each switch is as follows: the first isolating switch Q1, the second isolating switch Q2, and the circuit breaker CB are closed sequentially, resistor R2 is engaged to begin suppressing inrush current. When the control module detects a current signal in the converter transformer T, it sends a closing command to close the fast isolating switch DS2. After the fast isolating switch DS2 is in the closed position, resistor R2 is bypassed, ending the inrush current suppression.

[0079] The detection submodule 2011 is also specifically used for:

[0080] When a request to exit operation is received, a third control command is sent to the control submodule 2012, and when the second disconnecting switch Q2 of the combined electrical appliance C is detected to have been opened, a fourth control command is sent to the control submodule 2012.

[0081] The control submodule 2012 is also specifically used for:

[0082] In response to the first control command, the circuit breaker CB, the first disconnecting switch Q1, and the second disconnecting switch Q2 of the combined electrical appliance C are sent opening commands in sequence;

[0083] In response to the second control command, a tripping command is sent to the fast disconnect switch DS2 and a closing command is sent to the grounding switch ES2.

[0084] It should be noted that the operation logic of the switch when the converter transformer is taken out of operation is as follows: First, disconnect the circuit breaker CB, the first disconnecting switch Q1 and the second disconnecting switch Q2 in sequence. After confirming that the second disconnecting switch Q2 is in the open position, disconnect the fast disconnecting switch DS2. Finally, close the grounding switch ES2. At this time, the converter transformer circuit enters the maintenance mode.

[0085] The operating mechanism of the fast disconnect switch DS2 is a hydraulic operating mechanism, which is used to determine the action duration based on the received action command and then execute the corresponding action.

[0086] It should be noted that traditional fast disconnect switches use a spring operating mechanism to drive the crank arm to move, which in turn drives the main pull rod to perform opening and closing movements. The power source is the elastic potential energy provided by the cam of the spring operating mechanism compressing the spring. Once the cam and spring are determined, the output operating power is a fixed value, that is, the opening and closing speed is fixed, and it is impossible to adjust the opening and closing speed of the fast disconnect switch each time.

[0087] The hydraulic operating mechanism used in Embodiment 2 of the present invention is as follows: Figure 3 As shown, Figure 3 This is a schematic diagram of the hydraulic operating mechanism. The hydraulic operating mechanism includes a high-pressure oil chamber, a low-pressure oil chamber, a control valve, a disc spring, and a piston rod. In order to use the high and low oil pressure of hydraulic oil to drive the piston rod to perform opening and closing movements, the hydraulic oil pressure can be changed by controlling the flow rate of hydraulic oil, so that the movement speed of the piston rod can be controlled, thereby realizing the adjustment of the opening and closing speed of the switching device each time.

[0088] Optionally, the resistance value is greater than or equal to 1500Ω.

[0089] It should be noted that the process of confirming the specific resistance value is as follows: model the DC converter system; confirm the actual required resistance value through model simulation.

[0090] Optionally, the external structure of the suppression module 202 is a canister-type structure.

[0091] It should be noted that, for reference Figure 4 , Figure 4 This is a schematic diagram of the external structure of the suppression module. Area A is the bushing, and area B is a tank-type structure that houses components such as resistors, fast disconnect switches, grounding switches, and busbars. This structure allows for a compact suppression module, requiring less space compared to the open structure of a starting resistor excitation inrush current suppression device.

[0092] Embodiment 2 of this invention provides a converter transformer inrush current suppression device, applied to a converter transformer circuit with a voltage level of 550kV. The control module controls the closing action of the fast disconnect switch in the suppression module, thereby controlling the time when the resistor is connected to the converter transformer circuit. Since the response time of current control modules is generally 8ms to 10ms, and the fast disconnect switch can complete the action in about 30ms (with a dispersion of ±2ms), the resistor connection time of the converter transformer inrush current suppression device provided by this invention can reach 40ms. Furthermore, by improving the operating mechanism of the fast disconnect switch, the closing speed can be adjusted, allowing the resistor connection time to be further adjusted within the range where the resistor's thermal capacity meets the requirements, based on actual conditions. The resistor connection time is longer than that of the closing resistor inrush current suppression device, and much shorter than that of the starting resistor inrush current suppression device. This not only results in better inrush current suppression but also reduces the requirements for resistor thermal capacity, thus lowering the manufacturing cost of the inrush current suppression device.

[0093] In the several embodiments provided in this application, it should be understood that the disclosed devices, modules, and submodules can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces; indirect couplings or communication connections between devices or modules may be electrical, mechanical, or other forms.

[0094] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0095] Furthermore, the functional modules in the various embodiments of the present invention can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0096] If the integrated module is implemented as a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0097] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A converter transformer inrush current suppression device, characterized in that, The device, which is applied to a converter transformer circuit with a voltage level of 550kV, includes a control module and a suppression module. The suppression module is connected between the combined electrical appliance and the converter transformer in the converter transformer circuit; The control module is connected to the converter transformer, the combined electrical equipment, and the suppression module; The control module is used to send action commands to the combined electrical equipment and the suppression module when it receives a status request from the converter transformer and meets preset conditions. The suppression module includes a fast disconnect switch, a grounding switch, and a resistor; One end of the fast disconnect switch is connected to one end of the grounding switch to form a first branch; the other end of the grounding switch is connected to the ground. The first branch is connected in parallel with the resistor; The suppression module is used to respond to the action command and execute the actions of the fast disconnect switch and the grounding switch; The control module includes a detection submodule and a control submodule; The detection submodule is specifically used for: When a charging request is received, the time interval between the request time of the charging request and the obtained historical charging end time is calculated; If the time interval is less than a preset time threshold, the charging request is rejected. If the time interval is greater than or equal to a preset time threshold, the number of charging times is increased by a preset value, and it is determined whether the current number of charging times is greater than the preset number threshold. If the current number of charging cycles exceeds the preset number threshold, and the measured resistance temperature is higher than the measured ambient temperature, then the number of charging cycles is reset when the resistance temperature drops to the ambient temperature. If the current number of charging cycles is greater than the preset number threshold, and the measured resistance temperature is lower than or equal to the measured ambient temperature, then in response to the charging request, a first control command is sent to the control submodule, and when the circuit breaker of the combined electrical appliance is detected to be closed and the converter transformer has a current signal, a second control command is sent to the control submodule. If the current number of charging attempts is less than or equal to the preset number of attempts, then in response to the charging request, a first control command is sent to the control submodule, and when the circuit breaker of the combined electrical appliance is detected to be closed and the converter transformer has a current signal, a second control command is sent to the control submodule. The control submodule is specifically used for: In response to the first control command, closing commands are sequentially sent to the second disconnecting switch, the first disconnecting switch, and the circuit breaker of the combined electrical appliance; In response to the second control command, a closing command is sent to the fast disconnect switch.

2. The converter transformer inrush current suppression device according to claim 1, characterized in that, The detection submodule is also specifically used for: When a request to exit operation is received, a third control command is sent to the control submodule, and when the second disconnecting switch of the combined electrical appliance is detected to have been opened, a fourth control command is sent to the control submodule.

3. The converter transformer inrush current suppression device according to claim 2, characterized in that, The control submodule is also specifically used for: In response to the first control command, tripping commands are sent sequentially to the circuit breaker, the first disconnecting switch, and the second disconnecting switch of the combined electrical appliance; In response to the second control command, a tripping command is sent to the fast disconnecting switch, and a closing command is sent to the grounding switch.

4. The converter transformer inrush current suppression device according to claim 1, characterized in that, The operating mechanism of the fast disconnect switch is a hydraulic operating mechanism, which is used to determine the action duration and perform the corresponding action according to the received action command.

5. The converter transformer inrush current suppression device according to claim 1, characterized in that, The resistance value is greater than or equal to 1500Ω.

6. The converter transformer inrush current suppression device according to claim 1, characterized in that, The external structure of the suppression module is a canister-like structure.

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