Alternating current field discharge overvoltage protection device

Abstract

This invention belongs to the technical field of circuit protection devices, and relates to an AC excitation overvoltage protection device. The AC excitation overvoltage protection device includes an overvoltage power cabinet and an overvoltage control cabinet physically isolated from it. The overvoltage power cabinet contains an energy-consuming unit and a power unit electrically connected to each other. The overvoltage control cabinet contains a current-measuring unit, a valve control unit, and a power supply unit physically isolated from each other. The power supply unit supplies power to both the valve control unit and the power unit. The valve control unit is communicatively connected to the current-measuring unit and the power unit. Upon receiving an overvoltage signal, it actively sends a trigger signal to control the power unit to conduct, so that the energy generated by the overvoltage is diverted to the energy-consuming unit for consumption. This invention solves the problems of electromagnetic interference and electric shock risk associated with mixed high and low voltage circuits, improves the accuracy and reliability of overvoltage protection, and ensures the safe and stable operation of the AC excitation system and generator set.

Description

Technical Field

[0001] This invention belongs to the technical field of circuit protection devices, specifically relating to an AC excitation overvoltage protection device. Background Technology

[0002] During the operation of AC excitation equipment, transient overvoltages are easily generated in the core circuit of the excitation system due to various complex operating conditions such as grid dips, sudden load changes, or abnormal operation of internal components. If these overvoltages cannot be effectively suppressed and discharged within a very short time, the huge energy accumulated in the transients will directly break down the power semiconductor electronic components in the excitation system, and may even cause irreversible burnout of the motor rotor windings, thereby threatening the safe and stable operation of the entire generator set and the grid-connected power system. Therefore, configuring reliable overvoltage protection devices in the AC excitation system is a necessary measure to ensure the normal operation of the AC excitation system.

[0003] Currently, the industry typically uses a method of detecting the bus voltage threshold to trigger a short-circuit energy dissipation circuit for overvoltage protection. For example, Chinese Patent CN201623462U discloses an overvoltage protection device for an AC-AC excitation system. This device includes a detection unit and a power unit. The detection unit consists of a bridge detection circuit composed of fast diodes and transition diodes, while the power unit consists of two thyristors connected in anti-parallel and a RC snubber protection circuit. When an overvoltage occurs and its amplitude forcefully exceeds the physical breakdown threshold of the transition diode, the bridge detection circuit will naturally conduct and passively generate a trigger pulse, causing the thyristors in the power unit to conduct. This forces the large current generated by the overvoltage into an external energy-dissipating resistor for heat dissipation, thereby maintaining the excitation system voltage within a normal and safe range.

[0004] While the aforementioned overvoltage protection devices can provide overvoltage protection for AC excitation systems to a certain extent, they still have certain limitations in practical applications. These devices integrate the detection unit and power unit in the same physical space, meaning high-voltage power devices and low-voltage control components are mixed together. This makes the overvoltage protection device prone to generating strong electromagnetic fields during transient high-energy discharge, interfering with the normal operation of the low-voltage detection circuit, leading to decreased overvoltage detection accuracy and reduced reliability of the overvoltage protection. Furthermore, maintenance personnel need to contact both high- and low-voltage components during maintenance, posing a high risk of electric shock. In addition, both the primary power circuit and secondary control circuit of the aforementioned overvoltage protection devices adopt a single-circuit design; failure of any component will cause the entire protection function to fail, failing to meet the high reliability requirements of power systems for protection devices. Summary of the Invention

[0005] The purpose of this invention is to provide an AC excitation overvoltage protection device to solve the technical problem of low reliability of existing overvoltage protection devices.

[0006] To solve the above-mentioned technical problems, the present invention provides a technical solution for an AC excitation overvoltage protection device: An AC excitation overvoltage protection device, comprising: The overvoltage power cabinet contains an energy-consuming unit and a power unit, which are electrically connected. The overvoltage control cabinet is physically isolated from the overvoltage power cabinet. The overvoltage control cabinet is equipped with a physically isolated current measuring unit, valve control unit, and power supply unit. The power supply unit is electrically connected to the valve control unit and the power unit respectively. The valve control unit is communicatively connected to the current measuring unit and the power unit. It is used to actively send a trigger signal to control the power unit to conduct after receiving an overvoltage signal, so that the energy generated by the overvoltage is introduced into the energy consumption unit for consumption.

[0007] The beneficial effects of this invention are as follows: The AC excitation overvoltage protection device of this invention adopts a structure in which the overvoltage power cabinet and the overvoltage control cabinet are physically isolated. High-voltage power devices and low-voltage control components are placed in different cabinets, solving the electromagnetic interference problem caused by the mixing of high and low voltage components in existing technologies. This avoids the strong electromagnetic field generated by the high-voltage circuit affecting the normal operation of the low-voltage detection and control circuit, improving the overvoltage detection accuracy and the reliability of the protection action. Simultaneously, the physical isolation structure allows maintenance personnel to avoid contact with high-voltage components when inspecting the low-voltage control section, significantly reducing the risk of electric shock. Furthermore, compared with the passive triggering mode of existing technologies that rely on the physical breakdown threshold of devices, this invention uses a valve control unit to actively send a trigger signal to control the power unit's conduction, enabling more accurate identification of overvoltage signals and timely activation of protection, avoiding false triggering or protection delays.

[0008] Furthermore, the electrical circuit of the AC excitation overvoltage protection device includes a primary circuit and a secondary circuit, both of which are equipped with redundant designs.

[0009] Beneficial effects: The primary and secondary circuits of this invention are both equipped with redundant designs, which solves the single-point failure risk of the existing single-circuit design. When any component in one circuit fails, the other circuit can continue to perform overvoltage protection function, ensuring that the overvoltage protection device can still work normally in the event of failure of some components, thus meeting the high reliability requirements of the power system for overvoltage protection devices.

[0010] Furthermore, the redundancy design configuration of the primary and secondary circuits is as follows: The energy-consuming unit includes a dual parallel array of energy-consuming resistors, the power unit includes a redundant phase power valve string with a bidirectional current conduction path, and the power supply unit includes two independent power supply branches.

[0011] Beneficial effects: The energy dissipation unit adopts a dual parallel energy dissipation resistor array, which allows overvoltage energy to be consumed simultaneously through multiple sets of resistors. The failure of a single set of resistors will not interrupt the energy dissipation function of that phase. The power unit is equipped with redundant phase power valve strings with bidirectional current conduction paths, which can adapt to the bidirectional current characteristics of the AC excitation system. At the same time, a single branch failure will not affect the overall conduction of the power valve string. The power supply unit is equipped with two independent power supply branches to avoid the power failure of a single power supply branch causing the entire control and triggering system to lose power. The fault tolerance and reliability of the overvoltage protection device are improved from the three core aspects of energy dissipation, current conduction, and power supply.

[0012] Furthermore, the redundant phase power valve string has two input terminals, both of which adopt a bidirectional four-branch structure, including two forward-conducting branches and two reverse-conducting branches arranged in parallel. Each forward-conducting branch and each reverse-conducting branch includes at least two power devices connected in series. The two input terminals are respectively connected to a forward branch and a reverse branch. Each power device is provided with a trigger control unit to trigger the power device to conduct. The valve control unit is connected to the trigger control unit through an optical fiber and is used to send trigger pulse signals to the power device corresponding to the trigger control unit.

[0013] Beneficial effects: This invention can adapt to the bidirectional alternating current characteristics of AC excitation systems and handle overvoltage faults in both positive and negative half-cycles without the need for additional reverse protection circuits; it can also achieve precise control of each power device, avoiding the impact of a single trigger control unit failure on the conduction of multiple power devices; at the same time, the anti-interference characteristics of fiber optic transmission can ensure that the trigger pulse signal can be transmitted stably and quickly in a strong electromagnetic environment, improving the response speed and reliability of protection actions.

[0014] Furthermore, the trigger control unit is provided with a first support, a second support, a first feature hole, and a second feature hole; the power line of one power supply branch passes through the first support of each trigger control unit in sequence, and passes through the first feature hole of each trigger control unit in sequence on the return; the power line of the other power supply branch passes through the second support of each trigger control unit in sequence, and passes through the second feature hole of each trigger control unit in sequence on the return; the two power lines are energized at all times to supply power to all trigger control units through electromagnetic induction.

[0015] Beneficial effects: It eliminates the need for separate power lines for each trigger control unit, simplifying the wiring structure of the secondary circuit and reducing wiring failure points; the dual power lines are designed to be energized for extended periods, enabling the trigger control unit to draw power from both lines simultaneously. A single power line failure will not cause the trigger control unit to lose power, ensuring the power supply stability of the trigger control unit.

[0016] Furthermore, the energy-consuming unit and the power unit are arranged in layers in the overvoltage power cabinet, with the energy-consuming unit located on the upper layer and the power unit located on the lower layer; a heat dissipation structure is provided on the top of the overvoltage power cabinet corresponding to the position of the energy-consuming unit, and a ventilation structure is provided at the bottom of the cabinet door corresponding to the position of the power unit.

[0017] Beneficial effects: When the power-consuming unit is working, it generates a lot of heat. Hot air has a low density and will automatically flow upward. Placing the power-consuming unit at the top allows the heat to accumulate directly on the top of the cabinet. Combined with the top heat dissipation structure, the heat can be quickly discharged, preventing heat from accumulating inside the overvoltage power cabinet. Cool air can enter the overvoltage power cabinet from the bottom ventilation structure, first cooling the lower-temperature power units, then cooling the higher-temperature power-consuming units, and finally being discharged from the top of the cabinet, thus improving the overall heat dissipation efficiency of the overvoltage power cabinet.

[0018] Furthermore, the energy-consuming unit includes A-phase resistor groups, B-phase resistor groups and C-phase resistor groups arranged side by side at intervals; the A-phase resistor group includes at least two A-phase resistors arranged in parallel, the B-phase resistor group includes at least two B-phase resistors arranged in parallel, and the C-phase resistor group includes at least two C-phase resistors arranged in parallel, forming an array distribution.

[0019] Beneficial effects: It enables the overvoltage current of each phase to be evenly distributed across multiple resistors, reducing the current load of a single resistor; at the same time, the parallel arrangement of resistors forms a redundant backup, so that when a single resistor fails, the remaining resistors can still normally consume the overvoltage energy, ensuring the continuous operation capability of the energy-consuming unit.

[0020] Furthermore, the power unit includes an A-phase power valve string, a B-phase power valve string, and a C-phase power valve string, all of which are redundant phase power valve strings and are arranged sequentially from top to bottom inside the overvoltage power cabinet.

[0021] Beneficial effects: It optimizes the spatial layout inside the overvoltage power cabinet, makes the wiring path of the primary circuit more reasonable, and shortens the cable length.

[0022] Furthermore, a pressure relief port is provided on the top of the overvoltage power cabinet at the position corresponding to the energy consumption unit.

[0023] Beneficial effects: When the energy absorbed by the energy-consuming unit exceeds its tolerance limit and it explodes, the high-pressure gas generated inside the cabinet can be released upwards through the pressure relief port, preventing the pressure from being released from the cabinet door or the side of the cabinet and causing the cabinet to deform. This protects the safety of surrounding equipment and maintenance personnel and improves the protection capability of the device under extreme working conditions.

[0024] Furthermore, the current measuring unit, valve control unit, and power supply unit are arranged in layers from top to bottom in the overvoltage control cabinet.

[0025] Beneficial effects: It realizes the functional zoning within the overvoltage control cabinet, conforms to the wiring logic of the electrical system, makes the signal transmission and power supply line routing clearer, and reduces electromagnetic interference between different functional units; at the same time, the layering also makes it easier for maintenance personnel to inspect different functional units separately, improving the convenience and safety of maintenance. Attached Figure Description

[0026] Figure 1 This is a three-dimensional structural schematic diagram of the AC excitation overvoltage protection device of the present invention; Figure 2 This is a schematic diagram of the AC excitation overvoltage protection device of the present invention after the cabinet door has been removed; Figure 3 This is a schematic diagram of the energy-consuming unit. Figure 4 This is a schematic diagram of the power unit structure; Figure 5 This is a schematic diagram of the current measuring unit. Figure 6 This is a schematic diagram of the power supply unit. Figure 7 A schematic diagram showing the cable connection between the energy-consuming unit and the power unit; Figure 8 This is a schematic diagram of the A-phase power valve string structure; Figure 9 for Figure 8 Enlarged view of point D; Figure 10 This is the wiring diagram for the primary circuit.

[0027] Explanation of reference numerals in the attached figures: 1. Energy Consumption Unit; 101. First Phase A Resistor; 1011. First Terminal; 1012. Second Terminal; 102. Second Phase A Resistor; 1021. Third Terminal; 1022. Fourth Terminal; 103. First Phase B Resistor; 104. Second Phase B Resistor; 105. First Phase C Resistor; 106. Second Phase C Resistor; 11. Overvoltage Power Cabinet; 1101. First Fan; 1102. Second Fan; 1 103. First pressure relief port; 1104. Second pressure relief port; 1105. First cabinet door; 1106. First characteristic air inlet; 12. Overpressure control cabinet; 1201. Third pressure relief port; 1202. Fourth pressure relief port; 1203. Three-phase incoming line busbar; 1204. Second cabinet door; 1205. Second characteristic air inlet; 1206. High-voltage compartment; 2. Power unit; 201. A-phase power valve string; 2011. First power device; 20 12. Second power device; 2013. Third power device; 2014. Fourth power device; 2015. Fifth power device; 2016. Sixth power device; 2017. Seventh power device; 2018. Eighth power device; 2019. Trigger control unit; 20191. First feature hole; 20192. Second feature hole; 20193. First support; 20194. Second support; 202. B-phase power valve string; 203. C-phase power valve string; 204. First input terminal; 205. Second input terminal; 3. Current measurement unit; 301. A mutual inductor; 302. B mutual inductor; 303. C mutual inductor; 4. Valve control unit; 5. Power supply unit; 501. First isolation transformer; 502. Second isolation transformer; 503. First switching power supply; 504. Second switching power supply; 505. First high-frequency power supply; 506. Second high-frequency power supply. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0029] Embodiments of the AC excitation overvoltage protection device of the present invention: like Figure 1 As shown, the AC excitation overvoltage protection device includes an overvoltage power cabinet 11 and an overvoltage control cabinet 12. The overvoltage power cabinet 11 and the overvoltage control cabinet 12 are arranged side by side with physical isolation. The two are electrically connected and transmit signals through power cables and optical fibers.

[0030] like Figure 2As shown, the overvoltage power cabinet 11 integrates an energy-consuming unit 1 and a power unit 2, which are electrically connected via power cables. The overvoltage control cabinet 12 integrates a current-measuring unit 3, a valve control unit 4, and a power supply unit 5. The power supply unit 5 is electrically connected to both the valve control unit 4 and the power unit 2 via power cables, providing them with operating power. The valve control unit 4 is communicatively connected to both the current-measuring unit 3 and the power unit 2 via communication lines, receiving current signals collected by the current-measuring unit 3 and externally input voltage signals, and sending control commands to the power unit 2 based on the signal status.

[0031] In this embodiment, both the primary and secondary circuits of the AC excitation overvoltage protection device adopt a dual redundancy design. The redundancy design configuration of the primary and secondary circuits is as follows: the energy dissipation unit 1 includes a dual parallel energy dissipation resistor array, the power unit 2 includes a redundant phase power valve string with bidirectional current conduction path, and the power supply unit 5 includes two independent power supply branches.

[0032] Specifically, such as Figure 2 As shown, the internal space of the overvoltage power cabinet 11 is divided into upper and lower layers. The energy-consuming unit 1 is fixedly installed in the upper layer of the overvoltage power cabinet 11, and the power unit 2 is fixedly installed in the lower layer of the overvoltage power cabinet 11.

[0033] like Figure 2 and Figure 3 As shown, the energy-consuming unit 1 includes three resistor groups arranged side-by-side at intervals: an A-phase resistor group, a B-phase resistor group, and a C-phase resistor group. These three resistor groups are arranged sequentially along the width of the overvoltage power cabinet 11, with a pre-set ventilation gap between adjacent resistor groups. The A-phase resistor group includes a first A-phase resistor 101 and a second A-phase resistor 102 arranged in parallel; the B-phase resistor group includes a first B-phase resistor 103 and a second B-phase resistor 104 arranged in parallel; and the C-phase resistor group includes a first C-phase resistor 105 and a second C-phase resistor 106 arranged in parallel. The first A-phase resistor 101 and the second A-phase resistor 102 are respectively positioned at the front and rear of the upper right side of the overvoltage power cabinet 11; the first B-phase resistor 103 and the second B-phase resistor 104 are respectively positioned at the front and rear of the upper middle of the overvoltage power cabinet 11; and the first C-phase resistor 105 and the second C-phase resistor 106 are respectively positioned at the front and rear of the upper left side of the overvoltage power cabinet 11. All resistors are fixed to the upper mounting plate of the overvoltage power cabinet 11 by insulating supports, forming an array-like distribution structure. Each resistor has terminals at both ends. Resistors in the same phase are connected in parallel via copper busbars to form the energy-consuming branch of that phase. The wiring method of phase A resistor group will be explained as an example. Figure 7As shown, in this embodiment, the second terminal 1012 of the first A-phase resistor 101 and the third terminal 1021 of the second A-phase resistor 102 are connected by a copper busbar, and the A-phase incoming cable is connected to it. The outgoing terminals are the first terminal 1011 of the first A-phase resistor 101 and the fourth terminal 1022 of the second A-phase resistor 102. The wiring method of the B-phase and C-phase resistor groups is the same as that of the A-phase resistor group, and will not be described in detail here.

[0034] like Figure 2 and Figure 4 As shown, power unit 2 includes phase A power valve string 201, phase B power valve string 202, and phase C power valve string 203, which are arranged in layers from top to bottom inside the overvoltage power cabinet 11. Phase A power valve string 201, phase B power valve string 202, and phase C power valve string 203 are all redundant phase power valve strings, and their structures are identical. In this embodiment, the structure of phase A power valve string 201 is used as an example for explanation.

[0035] like Figure 7 As shown, the A-phase power valve string 201 has a first input terminal 204 and a second input terminal 205. The first terminal 1011 of the first A-phase resistor 101 is connected to the first input terminal 204 of the A-phase power valve string 201 via a cable. The fourth terminal 1022 of the second A-phase resistor 102 is connected to the second input terminal 205 of the A-phase power valve string 201 via a cable. The wiring for phases B and C is similar. Finally, the A-phase power valve string 201, B-phase power valve string 202, and C-phase power valve string 203 are short-circuited by a copper busbar.

[0036] like Figure 8 and Figure 10As shown, the A-phase power valve string 201 adopts a bidirectional four-branch structure, including two forward-conducting branches and two reverse-conducting branches arranged in parallel. The two forward-conducting branches are defined as the first forward-conducting branch and the second forward-conducting branch, and the two reverse-conducting branches are defined as the first reverse-conducting branch and the second reverse-conducting branch. The first forward-conducting branch and the first reverse-conducting branch are connected to the first incoming terminal 204, and the second forward-conducting branch and the second reverse-conducting branch are connected to the second incoming terminal 205. The first forward-conducting branch is composed of the first power device 2011 and the second power device 2012 connected in series, and the second forward-conducting branch is composed of the fifth power device 2015 and the sixth power device 2016 connected in series; the first reverse-conducting branch is composed of the third power device 2013 and the fourth power device 2014 connected in series, and the second reverse-conducting branch is composed of the seventh power device 2017 and the eighth power device 2018 connected in series. The second power device 2012 is shorted to the third power device 2013, the sixth power device 2016 is shorted to the seventh power device 2017, and the first power device 2011, the fourth power device 2014, the fifth power device 2015, and the eighth power device 2018 are shorted.

[0037] The current flow into phase A power valve string 201 is as follows: When forward current flows in, one path passes through the first input terminal 204, through the second power device 2012 and the first power device 2011, and another path passes through the second input terminal 205, through the sixth power device 2016 and the fifth power device 2015; when reverse current flows in, one path passes through the fourth power device 2014 and the fifth power device 2015 to the first input terminal 204, and another path passes through the eighth power device 2018 and the seventh power device 2017 to the second input terminal 205. The current flow in phase B power valve string 202 and phase C power valve string 203 is similar and will not be described in detail here.

[0038] In this embodiment, each power device is a thyristor device, and each power device is equipped with a corresponding trigger control unit 2019. The trigger control unit 2019 is electrically connected to the control electrode of the power device through a pin and is used to drive the power device to conduct. The valve control unit 4 is connected to the signal input terminal of each trigger control unit 2019 through multiple optical fibers and is used to send trigger pulse signals to the trigger control unit 2019.

[0039] like Figure 8 and Figure 9As shown, each trigger control unit 2019 is a cuboid insulating shell structure, with a first support 20193, a second support 20194, a first feature hole 20191, and a second feature hole 20192 on its shell. Both the first support 20193 and the second support 20194 have support holes, and the first support 20193 and the second support 20194 are arranged at intervals. The first feature hole 20191 and the second feature hole 20192 are circular through holes penetrating the shell, and are respectively arranged vertically corresponding to the first support 20193 and the second support 20194.

[0040] The overvoltage control cabinet 12 also adopts a layered structure, with its internal space divided into upper and lower layers for functional purposes. The current measuring unit 3 is fixedly installed in the upper area of ​​the overvoltage control cabinet 12, the valve control unit 4 is fixedly installed in the middle area of ​​the overvoltage control cabinet 12, and the power supply unit 5 is fixedly installed in the lower area of ​​the overvoltage control cabinet 12.

[0041] like Figure 5 As shown, the current measuring unit 3 includes mutual inductor A 301, mutual inductor B 302 and mutual inductor C 303. Mutual inductor A 301 is located on the upper left side of the overvoltage control cabinet 12, mutual inductor B 302 is located in the upper middle of the overvoltage control cabinet 12, and mutual inductor C 303 is located on the upper right side of the overvoltage control cabinet 12.

[0042] like Figure 2 As shown, the power supply unit 5 is fixedly installed in the lower high-voltage compartment 1206 of the overvoltage control cabinet 12, and includes two independent power supply branches. Figure 6 As shown, one power supply branch includes a first isolation transformer 501, a first switching power supply 503, and a first high-frequency power supply 505; the other power supply branch includes a second isolation transformer 502, a second switching power supply 504, and a second high-frequency power supply 506. The first isolation transformer 501 is located above the right side of the high-voltage compartment 1206 below the overvoltage control cabinet 12, and the second isolation transformer 502 is located below the right side of the high-voltage compartment 1206; the first switching power supply 503 is located above the center of the high-voltage compartment 1206, and the second switching power supply 504 is located below the center of the high-voltage compartment 1206; the first high-frequency power supply 505 is located above the left side of the high-voltage compartment 1206, and the second high-frequency power supply 506 is located below the left side of the high-voltage compartment 1206.

[0043] The first current path of the secondary circuit is as follows: the 220V current passes sequentially through the first isolation transformer 501, the first switching power supply 503, and the first high-frequency power supply 505. The purpose of the first isolation transformer 501 is to safely isolate the circuit and prevent electric shock. The first switching power supply 503 converts the 220V current into 48V DC current to power the first high-frequency power supply 505. The first power line connects to the output port of the first high-frequency power supply 505, passes sequentially through the first support 20193 on the eight trigger control units 2019 of the A-phase power valve string 201, then returns and passes sequentially through the first feature hole 20191 on the eight trigger control units 2019, then similarly passes through the B-phase power valve string 202 and the C-phase power valve string 203, and finally returns to the input port of the first high-frequency power supply 505. The first power line is energized when it is energized, and when energized, it will generate an induced magnetic field to power the 24 trigger control units 2019 in power unit 2. The second current path is as follows: the 220V current passes sequentially through the second isolation transformer 502, the second switching power supply 504, and the second high-frequency power supply 506. The second power line is connected from the output port of the second high-frequency power supply 506, passes sequentially through the second support 20194 on the eight trigger control units 2019 of the A-phase power valve string 201, then returns and passes sequentially through the second feature hole 20192 on the eight trigger control units 2019, then similarly passes through the B-phase power valve string 202 and the C-phase power valve string 203, and finally returns to the input port of the second high-frequency power supply 506.

[0044] In this embodiment, a heat dissipation structure and a pressure relief port are provided on the top of the overvoltage power cabinet 11 corresponding to the position of the energy-consuming unit 1. The heat dissipation structure includes a first fan 1101 located on the left rear side of the top of the overvoltage power cabinet 11 and a second fan 1102 located on the right rear side of the top of the cabinet, used to exhaust hot air inside the overvoltage power cabinet 11. The pressure relief port adopts a detachable metal cover structure, used to release high-pressure gas inside the overvoltage power cabinet 11 under extreme operating conditions. There are two pressure relief ports: a first pressure relief port 1103 located on the left front side of the top of the overvoltage power cabinet 11 and a second pressure relief port 1104 located on the right front side of the top of the overvoltage power cabinet 11. A first ventilation structure is provided at the bottom of the first cabinet door 1105 of the overvoltage power cabinet 11 corresponding to the position of the power unit 2. The first ventilation structure adopts a grille design and has multiple first characteristic air inlets 1106, used to guide external cold air into the overvoltage power cabinet 11. The overpressure control cabinet 12 has a third pressure relief port 1201 at the front of the top and a fourth pressure relief port 1202 at the rear of the top. The three-phase incoming line busbar 1203 is located in the middle of the top of the overpressure control cabinet 12. A second ventilation structure is located at the second cabinet door 1204 below the overpressure control cabinet 12. The second ventilation structure also adopts a grille design and has multiple second characteristic air inlets 1205, which are used to guide external cold air into the overpressure control cabinet 12.

[0045] The three-phase busbars of the AC excitation system are connected to the three-phase incoming busbar 1203 at the top of the overvoltage control cabinet 12 via power cables. The three-phase incoming busbar 1203 is connected to the primary input terminals of mutual inductors 301, 302, and 303 respectively via the A, B, and C phase copper busbars inside the cabinet. The primary output terminals of mutual inductors 301, 302, and 303 are connected to the input terminals of the A-phase resistor group, B-phase resistor group, and C-phase resistor group inside the overvoltage power cabinet 11 via power cables passing through the wall bushings on the side wall of the cabinet. The output terminals of the A-phase resistor group, B-phase resistor group, and C-phase resistor group are connected to the input terminals of the A-phase power valve string 201, B-phase power valve string 202, and C-phase power valve string 203 respectively via power cables. The output terminals of the three power valve strings are short-circuited together via a common copper busbar to form a complete primary current loop.

[0046] When the AC excitation overvoltage protection device is operating normally, the two power supply branches of power supply unit 5 work simultaneously, converting the external mains power into DC power of different levels to power valve control unit 4 and the two high-frequency power supplies respectively. The high-frequency current output from the two high-frequency power supplies flows in the two power lines, generating an alternating magnetic field, triggering control unit 2019 to obtain working power through electromagnetic induction and enter standby mode. Valve control unit 4 receives the three-phase current signal collected by current measurement unit 3 and the externally input AC excitation system bus voltage signal in real time, and performs real-time analysis and processing of the signals.

[0047] When an overvoltage fault occurs in the AC excitation system during the positive half-cycle of the AC current, the bus voltage exceeds the preset protection threshold. The valve control unit 4 immediately identifies the overvoltage state and simultaneously sends a trigger pulse signal to all trigger control units 2019 via optical fiber. After receiving the trigger pulse signal, the trigger control unit 2019 outputs a drive current to the control electrode of the corresponding power device, causing the first power device 2011 and the second power device 2012 on the first forward conduction branch to conduct, and the fifth power device 2015 and the sixth power device 2016 on the second forward conduction branch to conduct. This allows the overvoltage current to be distributed between the parallel first phase A resistor 101 and the second phase A resistor 102, thereby converting electrical energy into heat energy and dissipating the energy generated by the overvoltage.

[0048] Similarly, when an overvoltage fault occurs in the AC excitation system during the negative half-cycle of the AC current, the third power device 2013 and the fourth power device 2014 on the first reverse conduction branch are turned on, and the seventh power device 2017 and the eighth power device 2018 on the second reverse conduction branch are turned on, so that the overvoltage current is distributed between the first phase A resistor 101 and the second phase A resistor 102 connected in parallel, converting electrical energy into heat energy, and thus dissipating the energy generated by the overvoltage.

[0049] During the overvoltage energy dissipation process, the two fans at the top of the overvoltage power cabinet 11 automatically start, expelling hot air from inside the cabinet. External cold air enters the cabinet through the first characteristic air inlet 1106 at the bottom of the cabinet door, first cooling the lower power unit 2, and then flowing upwards to cool the upper energy-consuming unit 1, forming a continuous heat dissipation airflow to ensure the operating temperature of the power devices remains within the allowable range. If the energy absorbed by the energy-consuming unit 1 exceeds its withstand limit, the resistor ruptures, generating high-pressure gas. The pressure inside the cabinet will force open the covers at the first pressure relief port 1103 and the second pressure relief port 1104 at the top, allowing the high-pressure gas to be released upwards in a directional manner, preventing cabinet deformation or debris from flying.

[0050] Once the bus voltage of the AC excitation system returns to the normal range, valve control unit 4 stops sending trigger pulse signals, the power devices naturally turn off when the current crosses zero, and the primary circuit is disconnected. The heat dissipation structure continues to operate for a preset time before automatically stopping, and the device returns to normal standby mode, waiting for the next overvoltage event to occur.

[0051] In the above embodiments, both the primary and secondary circuits employ a dual redundancy design. In other embodiments, the primary and secondary circuits may also employ a triple redundancy design, with each phase of the energy-consuming unit 1 configured with three parallel resistors, the power supply unit 5 configured with three independent power supply branches, and the power valve series configured with three parallel forward conduction branches and three parallel reverse conduction branches, further enhancing the fault tolerance of the device. Of course, in other embodiments, redundancy design can be implemented according to actual needs.

[0052] In the above embodiments, the redundant phase power valve string adopts a bidirectional four-branch structure, containing eight power devices. In other embodiments, the redundant phase power valve string can also adopt a bidirectional six-branch structure, containing twelve power devices. Each forward and reverse conduction branch still consists of two power devices connected in series, suitable for applications with larger current carrying capacity. Of course, in other embodiments, the number of forward and reverse conduction branches and the number of power devices connected in series on each conduction branch can be reasonably arranged according to actual needs.

[0053] In the above embodiments, the current measuring unit 3, valve control unit 4 and power supply unit 5 in the overvoltage control cabinet 12 are arranged in layers from top to bottom along the height of the cabinet; in other embodiments, the current measuring unit 3, valve control unit 4 and power supply unit 5 can also be arranged in left and right compartments along the width of the cabinet, with each functional unit having an independent compartment to further improve the electromagnetic isolation effect.

[0054] While various embodiments of the invention have been shown and described in this specification, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and essence of the invention.

Claims

1. An alternating current field discharge overvoltage protection device, characterized by, include: The overvoltage power cabinet contains an energy-consuming unit and a power unit, which are electrically connected. The overvoltage control cabinet is physically isolated from the overvoltage power cabinet. The overvoltage control cabinet is equipped with a physically isolated current measuring unit, valve control unit, and power supply unit. The power supply unit is electrically connected to the valve control unit and the power unit respectively. The valve control unit is communicatively connected to the current measuring unit and the power unit. It is used to actively send a trigger signal to control the power unit to conduct after receiving an overvoltage signal, so that the energy generated by the overvoltage is introduced into the energy consumption unit for consumption.

2. The alternating current field generator overvoltage protection device of claim 1, wherein, The electrical circuit of the AC excitation overvoltage protection device includes a primary circuit and a secondary circuit, both of which are equipped with redundant designs.

3. The alternating current field generator overvoltage protection device of claim 2, wherein, The redundancy design configuration of the primary and secondary circuits is as follows: The energy-consuming unit includes a dual parallel array of energy-consuming resistors, the power unit includes a redundant phase power valve string with a bidirectional current conduction path, and the power supply unit includes two independent power supply branches.

4. The AC excitation overvoltage protection device according to claim 3, characterized in that, The redundant phase power valve string has two input terminals, both of which adopt a bidirectional four-branch structure, including two forward-conducting branches and two reverse-conducting branches arranged in parallel. Each forward-conducting branch and each reverse-conducting branch includes at least two power devices connected in series. The two input terminals are respectively connected to one forward branch and one reverse branch. Each power device is provided with a trigger control unit to trigger the power device to conduct. The valve control unit is connected to the trigger control unit through an optical fiber and is used to send trigger pulse signals to the power device corresponding to the trigger control unit.

5. The alternating current field generator overvoltage protection device of claim 4, wherein, The trigger control unit is provided with a first support, a second support, a first feature hole, and a second feature hole; the power line of one power supply branch passes through the first support of each trigger control unit in sequence, and passes through the first feature hole of each trigger control unit in sequence on the return; the power line of the other power supply branch passes through the second support of each trigger control unit in sequence, and passes through the second feature hole of each trigger control unit in sequence on the return; the two power lines are energized at all times to supply power to all trigger control units through electromagnetic induction.

6. The alternating current field generator overvoltage protection device of any of claims 3-5, wherein, The energy-consuming unit and the power unit are arranged in layers in the overvoltage power cabinet, with the energy-consuming unit located on the upper layer and the power unit located on the lower layer. A heat dissipation structure is provided on the top of the overvoltage power cabinet corresponding to the position of the energy-consuming unit, and a ventilation structure is provided at the bottom of the cabinet door corresponding to the position of the power unit.

7. The alternating current field generator overvoltage protection device of claim 6, wherein, The energy-consuming unit includes A-phase resistor groups, B-phase resistor groups and C-phase resistor groups arranged side by side at intervals; the A-phase resistor group includes at least two A-phase resistors arranged in parallel, the B-phase resistor group includes at least two B-phase resistors arranged in parallel, and the C-phase resistor group includes at least two C-phase resistors arranged in parallel, forming an array distribution.

8. The alternating current field generator overvoltage protection device of claim 7, wherein, The power unit includes an A-phase power valve string, a B-phase power valve string, and a C-phase power valve string. The A-phase power valve string, B-phase power valve string, and C-phase power valve string are all redundant phase power valve strings, and are arranged sequentially from top to bottom inside the overvoltage power cabinet.

9. The alternating current field generator overvoltage protection device of claim 6, wherein, The top of the overvoltage power cabinet is also equipped with a pressure relief port corresponding to the position of the energy-consuming unit.

10. The alternating current field generator overvoltage protection device of claim 1, wherein, The current measuring unit, the valve control unit and the power supply unit are arranged in layers from top to bottom in the overvoltage control cabinet.

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