A two-level protection power supply device and method for a steel-making furnace

Abstract

The application provides a kind of steel-making furnace mutual backup two-stage protection power supply device and power supply method, relate to metallurgical technical field, solve the technical problem that existing electric arc furnace, refining furnace and other steel-making furnace single circuit breaker power supply device lacks redundancy control and protection and fast switching capability.The device includes cabinet top incoming line isolation cabinet group, resistance-capacitance absorption outgoing line cabinet and vacuum circuit breaker cabinet group, vacuum circuit breaker cabinet group is at least two, vacuum circuit breaker cabinet group includes one running vacuum circuit breaker cabinet group and at least one standby vacuum circuit breaker cabinet group, each vacuum circuit breaker cabinet group is connected with cabinet top incoming line isolation cabinet group at one end, and is connected with resistance-capacitance absorption outgoing line cabinet at the other end.Through setting standby vacuum circuit breaker cabinet group, redundancy control and protection for steel-making furnace power supply are realized.When running vacuum circuit breaker cabinet group fails, standby vacuum circuit breaker cabinet group can be quickly put into use, ensure the continuous power supply of steel-making furnace, avoid production stagnation and equipment damage caused by power supply interruption.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, and in particular to a two-stage protection power supply device and power supply method for steelmaking furnaces. Background Technology

[0002] Electric arc furnaces and refining furnaces are key production equipment in the metallurgical industry. During continuous production, the high-voltage circuit breakers supplying them require frequent opening and closing operations. For example, the circuit breaker for a vertically feeding electric furnace can open and close an average of approximately 4,000 times per month. The on-site operating environment is harsh, with adverse factors such as high-current impact loads, dust, high temperatures, and strong magnetic fields. These significantly affect the safe and stable operation of the circuit breakers and high-voltage cabinets, easily leading to faults such as overheating of circuit breaker contacts, grounding, and short circuits. In severe cases, three-phase arc short circuits can cause explosions, resulting in internal deformation of the switchgear. Deformed cabinets require complete replacement and cannot be repaired on-site.

[0003] Currently, power supply systems for electric arc furnaces and refining furnaces generally adopt a single circuit breaker cabinet power supply mode, typically consisting of three 35kV KYN61-40.5 type high-voltage cabinets. From left to right, these are the top-mounted incoming isolation cabinet SA01, the vacuum circuit breaker cabinet SA02, and the RC absorption and outgoing cabinet SA03. This power supply device only has one vacuum circuit breaker as the sole control and protection unit, without a backup circuit breaker or backup high-voltage cabinet, and lacks redundant control and protection capabilities and rapid switching capabilities. When a serious fault occurs in the vacuum circuit breaker cabinet, resulting in burnt control cables, carbonized contact boxes, burned static contacts, reduced cabinet insulation, or even cabinet deformation, a power outage and major repairs are necessary.

[0004] Existing single-circuit breaker power supply systems have significant drawbacks: power cannot be quickly restored after a fault; even simple faults require prolonged power outages for repairs and circuit breaker replacement; and when the cabinet is severely deformed, the high-voltage cabinet must be custom-made, installed, and debugged, resulting in production downtime of up to a month. The direct production losses and indirect economic losses caused by power outages are substantial, severely impacting production continuity and corporate profitability. Therefore, it is necessary to optimize and improve the existing power supply systems for electric arc furnaces and refining furnaces. Summary of the Invention

[0005] The purpose of this invention is to provide a two-stage protection power supply device and method for steelmaking furnaces, which solves the technical problem that existing single-circuit breaker power supply devices for steelmaking furnaces such as electric arc furnaces and refining furnaces lack redundant control and protection and rapid switching capabilities. The various technical effects of the preferred solutions among the many technical solutions provided by this invention are detailed below.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The present invention provides a two-stage protection power supply device for steelmaking furnaces, comprising a cabinet top incoming isolation cabinet group, a resistor-capacitor absorption outgoing cabinet, and a vacuum circuit breaker cabinet group. There are at least two vacuum circuit breaker cabinet groups, each including one operating vacuum circuit breaker cabinet group and at least one standby vacuum circuit breaker cabinet group. Each vacuum circuit breaker cabinet group has one end connected to the cabinet top incoming isolation cabinet group and the other end connected to the resistor-capacitor absorption outgoing cabinet.

[0008] Preferably, the top-inlet isolation cabinet group and the vacuum circuit breaker cabinet group are connected by a first detachable copper busbar, and the first detachable copper busbar is located inside the top-inlet isolation cabinet group. The resistor-capacitor absorption outlet cabinet and the vacuum circuit breaker cabinet group are connected by a second detachable copper busbar, and the second detachable copper busbar is located inside the resistor-capacitor absorption outlet cabinet.

[0009] Preferably, the non-electrical protection signals of the transformer and the on-load tap changer are respectively connected to the first integrated protection device of the vacuum circuit breaker cabinet in the form of passive dry contacts.

[0010] Preferably, the top-mounted incoming line isolation cabinet group includes a top-mounted incoming line isolation cabinet and an incoming line CT cabinet. The incoming line CT cabinet is equipped with an upper-level integrated protection device. The number of upper-level integrated protection devices is the same as the number of vacuum circuit breaker cabinet groups. The upper-level integrated protection device in the incoming line CT cabinet realizes the control and protection of the vacuum circuit breaker cabinet group.

[0011] Preferably, the non-electrical protection signals of the transformer and the on-load tap changer are respectively connected to the upper-level integrated protection device in the form of passive dry contacts.

[0012] Preferably, each vacuum circuit breaker cabinet includes at least two sets of circuit breaker assemblies connected in parallel. Each circuit breaker assembly includes a circuit breaker and a second integrated protection device. At least two of the circuit breakers are switched on and off synchronously. Each set of the second integrated protection device can realize the control and protection of the vacuum circuit breaker cabinet.

[0013] Preferably, a tripping relay is installed in the incoming CT cabinet, and the tripping relay has at least two tripping dry contacts; At least two of the aforementioned tripping dry contacts are respectively connected to the manual tripping input terminals of at least two sets of the second integrated protection devices in the same vacuum circuit breaker cabinet group via wires; When the trip relay operates, at least two circuit breakers in the vacuum circuit breaker cabinet are simultaneously triggered to trip by at least two sets of the second integrated protection devices in the vacuum circuit breaker cabinet.

[0014] Preferably, a closing relay is installed in the incoming CT cabinet, and the closing relay has at least two closing dry contacts; At least two of the closing dry contacts are connected to the closing input terminals of at least two sets of the second integrated protection devices in the same vacuum circuit breaker cabinet group via wires; When the closing relay operates, at least two sets of the second integrated protection devices in the vacuum circuit breaker cabinet will be simultaneously triggered to close at least two circuit breakers in the vacuum circuit breaker cabinet.

[0015] The present invention provides a power supply method for a two-stage protection power supply device for a steelmaking furnace as described above, comprising: The non-electrical signals of the transformer body and the on-load tap changer are connected to at least two sets of integrated protection devices in the incoming CT cabinet in the form of passive dry contacts. When the load-side current exceeds the protection setting: Each set of first integrated protection devices in the corresponding operating vacuum circuit breaker cabinet group sends a trip signal to cause the operating vacuum circuit breaker cabinet group to trip. Alternatively, the upstream integrated protection device corresponding to the operating vacuum circuit breaker cabinet group can issue two sets of protection trip signals. The protection trip signals can act on the second integrated protection device in the vacuum circuit breaker cabinet group, causing the operating vacuum circuit breaker cabinet group to trip. Alternatively, the second integrated protection device in the operating vacuum circuit breaker cabinet group sends out two sets of protection trip signals. The first set of protection trip signals causes the circuit breaker to trip, and the other set of trip signals acts on the second integrated protection device of another circuit breaker in the same group, causing the other circuit breaker to trip, thus completing the tripping of the operating vacuum circuit breaker cabinet group. When the transformer malfunctions: Non-electrical signals are sent to each of the first integrated protection devices. The first integrated protection devices in operation issue alarm or protection trip signals according to the signal type. The trip signal causes the operating vacuum circuit breaker cabinet group to trip. Alternatively, non-electrical signals are sent to each of the higher-level integrated protection devices. The higher-level integrated protection devices in operation issue alarm or protection trip signals according to the signal type. The protection trip signal acts on the second integrated protection device in the operating vacuum circuit breaker cabinet group, causing the operating vacuum circuit breaker cabinet group to trip. When a fault occurs in the operating vacuum circuit breaker cabinet and power supply is unavailable, the following switching procedures shall be performed: Disconnect the control power supply of the operating vacuum circuit breaker cabinet group; Open the incoming line isolating switch and complete the load-side grounding; Remove the detachable copper busbars connecting the operating vacuum circuit breaker cabinet to the adjacent cabinet to physically disconnect the faulty circuit. Connect the control power supply of the backup vacuum circuit breaker cabinet and restore the incoming isolating switch to the operating state; Put the standby vacuum circuit breaker cabinet into operation and restore power supply.

[0016] Preferably, the circuit breaker status signal and the non-electrical protection signals of the transformer and on-load tap changer are output in the form of passive dry contacts, or extended into passive dry contacts via intermediate relays and then connected to the PLC remote station.

[0017] The application employs the above technical solution and has at least the following beneficial effects: A two-stage backup protection power supply device for a steelmaking furnace includes a top-mounted incoming isolation cabinet group, a resistor-capacitor (RC) absorption outgoing cabinet, and a vacuum circuit breaker cabinet group. There are at least two vacuum circuit breaker cabinet groups, each comprising one operating vacuum circuit breaker cabinet group and at least one standby vacuum circuit breaker cabinet group. Each vacuum circuit breaker cabinet group has one end connected to the top-mounted incoming isolation cabinet group and the other end connected to the RC absorption outgoing cabinet group. By setting up a standby vacuum circuit breaker cabinet group, when the operating vacuum circuit breaker cabinet group fails, the standby vacuum circuit breaker cabinet group can be quickly connected to the circuit, reducing power outage time caused by the fault. Simultaneously, this backup design also improves the reliability of the entire power supply system and reduces the risk of production interruption caused by a single fault.

[0018] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0019] 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.

[0020] Figure 1 This is a schematic diagram of the structure of one embodiment of the two-stage protection power supply device for steelmaking furnaces provided in this invention. Figure 2 This is a schematic diagram of another embodiment of the two-stage protection power supply device for steelmaking furnaces provided in this invention.

[0021] In the diagram: 1. Top-mounted incoming isolation cabinet group; 101. Top-mounted incoming isolation cabinet; 102. Incoming CT cabinet; 2. RC absorption outgoing cabinet; 3. Vacuum circuit breaker cabinet group; 4. First detachable copper busbar; 5. Second detachable copper busbar; 6. First integrated protection device; 7. Upper-level integrated protection device; 8. Second integrated protection device. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0023] A specific embodiment of the present invention provides a two-stage backup power supply device for a steelmaking furnace, comprising a top-mounted incoming isolation cabinet group 1, a resistor-capacitor (RC) absorption outgoing cabinet group 2, and a vacuum circuit breaker cabinet group 3. There are at least two vacuum circuit breaker cabinet groups 3, each including one operating vacuum circuit breaker cabinet group 3 and at least one standby vacuum circuit breaker cabinet group 3. Each vacuum circuit breaker cabinet group 3 has one end connected to the top-mounted incoming isolation cabinet group 1 and the other end connected to the RC absorption outgoing cabinet group 2. When the operating vacuum circuit breaker cabinet group 3 fails or requires maintenance, the standby vacuum circuit breaker cabinet group 3 can be quickly put into use, ensuring the continuity and stability of the power supply to the steelmaking furnace. This design effectively avoids power outages to the steelmaking furnace due to a single vacuum circuit breaker cabinet group 3 failure, greatly reducing the risk of production stoppage and minimizing economic losses caused by power supply problems. In this way, the entire two-stage backup power supply device for the steelmaking furnace can better meet the stringent requirements for stable power supply during steelmaking production, providing a strong guarantee for the efficient and safe operation of steelmaking.

[0024] In specific embodiments of this application, in conjunction with the appendix Figure 1 and attached Figure 2 As shown, the top-mounted incoming isolation cabinet 1 and the vacuum circuit breaker cabinet 3 are connected by a first detachable copper busbar 4, which is located inside the top-mounted incoming isolation cabinet 1. The resistor-capacitor (RC) absorption outgoing cabinet 2 and the vacuum circuit breaker cabinet 3 are connected by a second detachable copper busbar 5, which is located inside the RC absorption outgoing cabinet 2. The use of the first detachable copper busbar 4 facilitates disconnection between the top-mounted incoming isolation cabinet 1 and the vacuum circuit breaker cabinet 3; the use of the second detachable copper busbar 5 facilitates disconnection between the RC absorption outgoing cabinet 2 and the vacuum circuit breaker cabinet 3. Furthermore, by placing the first detachable copper busbar 4 and the second detachable copper busbar 5 in adjacent cabinets of the vacuum circuit breaker cabinet 3, the circuit breaker cabinet 3 will have no external electrical connections after the removal of the detachable copper busbars in adjacent cabinets, ensuring safety during maintenance and modification of the decommissioned circuit breaker cabinets.

[0025] In specific embodiments of this application, in conjunction with the appendix Figure 1 As shown: The cabinet group 1 consists of a separate top-incoming isolation cabinet SA01; the RC absorption outgoing cabinet 2 consists of a separate RC absorption and outgoing cabinet SA03; and the vacuum circuit breaker cabinet group 3 includes vacuum circuit breaker cabinets SA02 and SA04; both vacuum circuit breaker cabinets are equipped with the first integrated protection device 6. Under normal circumstances, either SA02 or SA04 circuit breaker can be set to operating status, while the other can be set to standby status. The secondary control circuit of the operating circuit breaker must be kept energized, while the secondary control circuit of the standby circuit breaker must be kept de-energized.

[0026] Non-electrical protection signals of the transformer and on-load tap changer are connected to the first integrated protection device 6 in the form of passive dry contacts. Specifically, non-electrical signals such as light gas, heavy gas, pressure release, and oil surface temperature of the transformer body and non-electrical signals such as light gas and heavy gas of the on-load tap changer are connected to two sets of the first integrated protection device 6 in the form of dry contacts. This is a conventional technical solution and will not be described in detail.

[0027] If the PLC remote station requires circuit breaker status signals and transformer non-electrical signals, it needs to provide passive contacts or expand the passive contacts through intermediate relays. Specifically, to collect circuit breaker position and transformer non-electrical signals, the PLC remote station must use non-energized switch contacts (passive contacts). If the original equipment contacts are insufficient, an intermediate relay should be added to convert the signals into multiple sets of passive contacts before sending them to the PLC.

[0028] In specific embodiments of this application, in conjunction with the appendix Figure 2 As shown: The top-mounted incoming line isolation cabinet group 1 includes a top-mounted incoming line isolation cabinet 101 and an incoming line CT cabinet 102, which is also attached. Figure 2 The cabinet includes top-mounted incoming isolation cabinet SA01-1 and incoming CT cabinet SA01-2; RC absorption outgoing cabinet 2 is a separate RC absorption and outgoing cabinet SA03; and vacuum circuit breaker cabinet group 3 includes vacuum circuit breaker cabinet SA02-1, vacuum circuit breaker cabinet SA02-2, vacuum circuit breaker cabinet SA04-1 and vacuum circuit breaker cabinet SA04-2.

[0029] The SA02-1 circuit breaker cabinet and the SA02-2 circuit breaker cabinet are combined to form the SA02 circuit breaker cabinet group. The opening and closing of the two circuit breaker cabinets must be synchronized.

[0030] The SA04-1 circuit breaker cabinet and the SA04-2 circuit breaker cabinet are combined to form the SA04 circuit breaker cabinet group. The opening and closing of the two circuit breaker cabinets must be synchronized.

[0031] In the incoming line CT cabinet 102, a superior comprehensive protection device 7 is provided. The number of superior comprehensive protection devices 7 is the same as the number of vacuum circuit breaker cabinet groups 3, and each vacuum circuit breaker cabinet group 3 is respectively connected to the incoming line isolation cabinet 101 at the cabinet top through a second comprehensive protection device 8. Specifically, two sets of superior comprehensive protection devices 7 are installed in the incoming line CT cabinet SA01-2 cabinet, which are respectively the comprehensive protection for the vacuum circuit breaker cabinet group 3. Each comprehensive protection device has two pairs of dry contacts for protection tripping outlets that can act synchronously.

[0032] In each of the four circuit breaker cabinets supporting the SA02 circuit breaker cabinet group and the SA04 circuit breaker cabinet group, a set of second comprehensive protection device 8 is installed. Each comprehensive protection device has two pairs of dry contacts for protection tripping outlets that can act synchronously.

[0033] Under normal circumstances, either the SA02 circuit breaker cabinet group or the SA04 circuit breaker cabinet group can be arbitrarily set to the operating state, and the other group is set to the standby state. The secondary control circuit of the operating circuit breaker cabinet group must remain powered on, and the secondary control circuit of the standby circuit breaker cabinet group must remain powered off.

[0034] Non-electric quantity signals such as light gas, heavy gas, oil surface temperature, and pressure release of the transformer body, and non-electric quantity signals such as light gas and heavy gas of the on-load tap-changer are respectively connected to the two sets of superior comprehensive protection devices 7 (SA02 comprehensive protection and SA04 comprehensive protection) in the incoming line CT cabinet SA01-2 cabinet in the form of dry contacts.

[0035] If the PLC remote station needs the circuit breaker status signal and the transformer non-electric quantity signal, it needs to provide a passive point or expand the passive point through an intermediate relay to achieve it. The specific method is the same as the above embodiment.

[0036] In some embodiments, a shunt relay is provided in the incoming line CT cabinet 102, and the shunt relay has at least two shunt dry contacts; At least two shunt dry contacts are respectively connected to the manual tripping input terminals on the second comprehensive protection 8 in the same vacuum circuit breaker cabinet group 3 through wires; When the shunt relay operates, it synchronously triggers the two sets of second comprehensive protection devices 8 in the circuit breaker cabinet group, causing the two circuit breakers to trip.

[0037] For example, when it is necessary to perform local or remote shunt on the SA02 circuit breaker cabinet group, only one shunt relay needs to be installed in the incoming line CT cabinet SA01-2. The two pairs of dry contacts of the shunt relay are respectively connected to the manual tripping input terminals of the second comprehensive protection device 8 in the SA02-1 circuit breaker cabinet and the second comprehensive protection device 8 in the SA02-2 circuit breaker cabinet through wires. When the shunt relay contact closes, the shunt power supply respectively connects to the tripping coils of the SA02-1 circuit breaker and the SA02-2 circuit breaker through the second comprehensive protection device 8, causing the SA02 circuit breaker cabinet group to trip.

[0038] In some embodiments, a closing relay is provided in the incoming CT cabinet 102, and the closing relay has at least two closing dry contacts; At least two closing dry contacts are connected to the closing input terminal of the second integrated protection device 8 in the same vacuum circuit breaker cabinet group 3 via wires; When the closing relay operates, it simultaneously triggers the two sets of second integrated protection devices 8 in the circuit breaker cabinet group, causing the two circuit breakers to close.

[0039] For example, when it is necessary to close the SA02 circuit breaker cabinet locally or remotely, only one closing relay needs to be installed in the incoming CT cabinet SA01-2. The two pairs of dry contacts of the relay are connected to the closing input terminals of the second integrated protection device 8 in cabinet SA02-1 and cabinet SA02-2 respectively through wires. When the closing relay contacts are closed, the closing power supply is connected to the closing coils of circuit breaker SA02-1 and SA02-2 respectively through the second integrated protection device 8, so that the SA02 circuit breaker cabinet can be closed.

[0040] A specific embodiment of the present invention provides a power supply method for the above-mentioned two-stage protection power supply device for steelmaking furnaces, comprising: Non-electrical signals from the transformer body and the on-load tap changer are connected to at least two sets of integrated protection devices via passive dry contacts. These integrated protection devices are attached... Figure 1 The first integrated protection device 6 shown or attached Figure 2 The upper-level integrated protection device 7 is shown; When the load-side current exceeds the protection setting: See appendix Figure 1 Two sets of trip signals are issued by the first integrated protection device 6 corresponding to the operating vacuum circuit breaker cabinet group 3, causing the operating vacuum circuit breaker cabinet group 3 to trip. Alternatively, see appendix. Figure 2 Two sets of protection trip signals are issued by the upper-level integrated protection device 7 corresponding to the operating vacuum circuit breaker cabinet group 3. The protection trip signals act on the two sets of second integrated protection devices 8 of the circuit breaker cabinet group 3 respectively, causing the operating vacuum circuit breaker cabinet group 3 to trip. Alternatively, see appendix. Figure 2 Two sets of protection trip signals are issued by the second integrated protection device 8 in the operating vacuum circuit breaker cabinet group 3. The first set of protection trip signals causes this circuit breaker to trip, and the other set of trip signals acts on the second integrated protection device 8 of another circuit breaker in this group, causing the other circuit breaker to trip, thus completing the tripping of the operating vacuum circuit breaker cabinet group 3. When the transformer malfunctions: See appendix Figure 1Non-electrical signals are sent to each of the first integrated protection devices 6. The first integrated protection device 6 in operation issues an alarm or protection trip signal according to the signal type. The trip signal causes the operating vacuum circuit breaker cabinet group 3 to trip. Alternatively, see appendix. Figure 2 Non-electrical signals are sent to each of the upper-level integrated protection devices 7. The upper-level integrated protection devices 7 in operation issue alarm or protection trip signals according to the signal type. The protection trip signal acts on the second integrated protection device 8 in the operating vacuum circuit breaker cabinet group, causing the operating vacuum circuit breaker cabinet group to trip. When the operating vacuum circuit breaker cabinet group 3 fails and cannot supply power, the following switching steps shall be performed: Disconnect the control power supply of the operating vacuum circuit breaker cabinet group; Open the incoming line isolating switch and complete the load-side grounding; Remove the detachable copper busbars connecting the operating vacuum circuit breaker cabinet to the adjacent cabinet to physically disconnect the faulty circuit. Connect the control power supply of the backup vacuum circuit breaker cabinet and restore the incoming isolating switch to the operating state; Put the standby vacuum circuit breaker cabinet into operation and restore power supply.

[0041] In some embodiments, as shown in the appendix Figure 1 The illustrated two-stage protection power supply device for the steelmaking furnace is explained using the SA02 circuit breaker in operation and the SA04 circuit breaker in standby status as an example. (1) When the load side current is too high and exceeds the protection setting, the SA02 integrated protection device sends a trip signal to trip the SA02 circuit breaker.

[0042] (2) When the transformer malfunctions, non-electrical signals will be sent to the SA02 integrated protection device and the SA04 integrated protection device respectively. Among them, the SA02 integrated protection device in operation will issue an alarm signal and a protection trip signal according to the signal type. The trip signal will cause the SA02 circuit breaker to trip.

[0043] (3) When the SA02 circuit breaker malfunctions during operation, causing carbonization of the contact box inside the cabinet, burnt static contacts, reduced cabinet insulation, burned wires inside the cabinet, or deformation of the cabinet preventing normal power supply, the operator should first disconnect the secondary control power supply of the SA02 circuit breaker, then open the incoming line isolating switch SA01, ground it on the load side, and then remove the detachable copper busbar connecting the incoming line side of the SA01 cabinet to the SA02 cabinet and the detachable copper busbar connecting the outgoing line side of the SA03 cabinet to the SA02 cabinet. After completely disconnecting the electrical connection between the SA02 cabinet and the adjacent cabinet, close the secondary control power supply of the SA04 circuit breaker. Change the incoming line isolating switch SA01 from maintenance status to operating status, and change the SA04 circuit breaker from standby status to operating status. After completing the above operations, the power supply to the electric furnace can be restored. This operation can be completed within 30 minutes.

[0044] In some embodiments, as shown in the appendix Figure 2 The illustrated two-stage protection power supply device for the steelmaking furnace is shown below. Taking the SA02 circuit breaker cabinet group in operation and the SA04 circuit breaker cabinet group in standby state as examples, the working method of this power supply device is explained: (1) When the load-side current exceeds the protection setting, the SA02-1 integrated protection device will issue a protection trip signal, causing the SA02-1 circuit breaker cabinet to trip. Simultaneously, the SA02-1 integrated protection device will issue a second protection trip signal, which will be connected to the protection trip input terminal of the SA02-2 integrated protection device in the form of a dry contact, connecting the SA02-2 integrated protection trip circuit, and causing the SA02-2 circuit breaker cabinet to trip. This achieves the protection tripping of the SA02 circuit breaker cabinet group.

[0045] (2) Similarly, when the SA02-2 integrated protection device detects an abnormal current that exceeds the protection setting, it will issue a protection trip signal, causing the SA02-2 circuit breaker cabinet to trip. At the same time, the SA02-2 integrated protection device simultaneously issues a second protection trip signal, which is connected to the protection trip input terminal of the SA02-1 integrated protection device in the form of a dry contact, connecting the SA02-1 integrated protection trip circuit, and causing the SA02-1 circuit breaker cabinet to trip. This achieves the protection tripping of the SA02 circuit breaker cabinet group.

[0046] (3) When the SA02 integrated protection device in the upstream incoming CT cabinet SA01-2 detects an abnormal current exceeding the protection setting, the SA02 integrated protection device simultaneously sends two protection trip signals. The two protection trip signals are respectively connected to the protection trip input terminal of the SA02-1 integrated protection device in the form of dry contacts, and the circuit breaker tripping circuit is connected through the SA02-1 integrated protection device, causing the SA02-1 circuit breaker cabinet to trip; and connected to the protection trip input terminal of the SA02-2 integrated protection device, and the circuit breaker tripping circuit is connected through the SA02-2 integrated protection device, causing the SA02-2 circuit breaker cabinet to trip. The protection tripping of the SA02 circuit breaker cabinet group is realized.

[0047] (4) When the SA02 integrated protection device in the upstream incoming CT cabinet SA01-2 detects a non-electrical quantity signal from the transformer, the SA02 integrated protection device simultaneously sends two protection trip signals. The two protection trip signals are respectively connected to the protection trip input terminal of the SA02-1 integrated protection device in the form of dry contacts, and the circuit breaker tripping circuit is connected through the SA02-1 integrated protection device, causing the SA02-1 circuit breaker cabinet to trip; and connected to the protection trip input terminal of the SA02-2 integrated protection device, and the circuit breaker tripping circuit is connected through the SA02-2 integrated protection device, causing the SA02-2 circuit breaker cabinet to trip. The protection tripping of the SA02 circuit breaker cabinet group is realized.

[0048] (5) When the SA02 circuit breaker cabinet suddenly malfunctions or deforms during operation, preventing normal power supply, the operator should first disconnect the secondary control power supply of the SA02 circuit breaker cabinet, then open the incoming isolating switch SA01-1, ground it on the load side, and then remove the detachable copper busbar connecting the incoming side of the SA02-1 cabinet in the SA01-2 cabinet and the detachable copper busbar connecting the outgoing side of the SA02-2 cabinet in the SA03 cabinet. After physically disconnecting the electrical connection between the two high-voltage cabinets of the SA02 circuit breaker cabinet and the adjacent cabinet, close the secondary control power supply of the SA04 circuit breaker cabinet. Change the incoming isolating switch SA01-1 from maintenance status to operating status, and change the SA04 circuit breaker cabinet from standby status to operating status. After completing the above operations, the power supply to the electric furnace can be restored. This operation can be completed within 30 minutes.

[0049] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," and "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0050] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A two-stage protection power supply device for a steelmaking furnace, characterized in that, It includes a top-mounted incoming isolation cabinet group, a resistor-capacitor absorption outgoing cabinet, and a vacuum circuit breaker cabinet group. There are at least two vacuum circuit breaker cabinet groups. Each vacuum circuit breaker cabinet group includes one operating vacuum circuit breaker cabinet group and at least one standby vacuum circuit breaker cabinet group. Each vacuum circuit breaker cabinet group has one end connected to the top-mounted incoming isolation cabinet group and the other end connected to the resistor-capacitor absorption outgoing cabinet group.

2. The two-stage protection power supply device for steelmaking furnaces according to claim 1, characterized in that, The top-inlet isolation cabinet group and the vacuum circuit breaker cabinet group are connected by a first detachable copper busbar, and the first detachable copper busbar is located inside the top-inlet isolation cabinet group. The resistor-capacitor absorption outlet cabinet and the vacuum circuit breaker cabinet group are connected by a second detachable copper busbar, and the second detachable copper busbar is located inside the resistor-capacitor absorption outlet cabinet.

3. The two-stage protection power supply device for steelmaking furnaces according to claim 2, characterized in that, The non-electrical protection signals of the transformer and the on-load tap changer are respectively connected to the first integrated protection device of the vacuum circuit breaker cabinet in the form of passive dry contacts.

4. The two-stage protection power supply device for steelmaking furnaces according to claim 2, characterized in that, The top-mounted incoming isolation cabinet group includes a top-mounted incoming isolation cabinet and an incoming CT cabinet. The incoming CT cabinet is equipped with an upper-level integrated protection device. The number of the upper-level integrated protection devices is the same as the number of the vacuum circuit breaker cabinet group. The upper-level integrated protection device in the incoming CT cabinet realizes the control and protection of the vacuum circuit breaker cabinet group.

5. The two-stage protection power supply device for steelmaking furnaces according to claim 4, characterized in that, Non-electrical protection signals of the transformer and on-load tap changer are respectively connected to the upper-level integrated protection device in the form of passive dry contacts.

6. The two-stage protection power supply device for steelmaking furnaces according to claim 4, characterized in that, Each of the vacuum circuit breaker cabinets includes at least two sets of circuit breaker assemblies connected in parallel. Each circuit breaker assembly includes a circuit breaker and a second integrated protection device. At least two of the circuit breakers are switched on and off synchronously. Each set of the second integrated protection device can realize the control and protection of the vacuum circuit breaker cabinet.

7. The two-stage protection power supply device for steelmaking furnaces according to claim 5, characterized in that, The incoming CT cabinet is equipped with a tripping relay, which has at least two tripping dry contacts. At least two of the aforementioned tripping dry contacts are respectively connected to the manual tripping input terminals of at least two sets of the second integrated protection devices in the same vacuum circuit breaker cabinet group via wires; When the trip relay operates, at least two circuit breakers in the vacuum circuit breaker cabinet are simultaneously triggered to trip by at least two sets of the second integrated protection devices in the vacuum circuit breaker cabinet.

8. The two-stage protection power supply device for steelmaking furnaces according to claim 5, characterized in that, The incoming CT cabinet is equipped with a closing relay, which has at least two closing dry contacts. At least two of the closing dry contacts are connected to the closing input terminals of at least two sets of the second integrated protection devices in the same vacuum circuit breaker cabinet group via wires; When the closing relay operates, at least two sets of the second integrated protection devices in the vacuum circuit breaker cabinet will be simultaneously triggered to close at least two circuit breakers in the vacuum circuit breaker cabinet.

9. A power supply method for a two-stage protection power supply device for a steelmaking furnace as described in any one of claims 1 to 8, characterized in that, include: The non-electrical signals of the transformer body and the on-load tap changer are connected to at least two sets of upstream integrated protection devices in the incoming CT cabinet in the form of passive dry contacts. When the load-side current exceeds the protection setting: The first integrated protection device corresponding to the operating vacuum circuit breaker cabinet group sends two sets of trip signals, causing the operating vacuum circuit breaker cabinet group to trip. Alternatively, the upper-level integrated protection device corresponding to the operating vacuum circuit breaker cabinet group can issue two sets of protection trip signals. The protection trip signals can act on the two sets of second integrated protection devices in the vacuum circuit breaker cabinet group, causing the operating vacuum circuit breaker cabinet group to trip. Alternatively, the second integrated protection device within the operating vacuum circuit breaker cabinet group sends out two sets of protection trip signals. The first set of protection trip signals causes the circuit breaker to trip, and the other set of trip signals acts on the second integrated protection device of another circuit breaker in the same group, causing the other circuit breaker to trip, thus completing the tripping of the operating vacuum circuit breaker cabinet group. When the transformer malfunctions Non-electrical signals are sent to each of the first integrated protection devices. The first integrated protection devices in operation issue alarm or protection trip signals according to the signal type. The trip signal causes the operating vacuum circuit breaker cabinet group to trip. Alternatively, non-electrical signals are sent to each of the higher-level integrated protection devices. The higher-level integrated protection devices in operation issue alarm or protection trip signals according to the signal type. The protection trip signal acts on the second integrated protection device in the operating vacuum circuit breaker cabinet group, causing the operating vacuum circuit breaker cabinet group to trip. When a fault occurs in the operating vacuum circuit breaker cabinet and power supply is unavailable, the following switching procedures shall be performed: Disconnect the control power supply of the operating vacuum circuit breaker cabinet group; Open the incoming line isolating switch and complete the load-side grounding; Remove the detachable copper busbars connecting the operating vacuum circuit breaker cabinet to the adjacent cabinet to physically disconnect the faulty circuit. Connect the control power supply of the backup vacuum circuit breaker cabinet and restore the incoming isolating switch to the operating state; Put the standby vacuum circuit breaker cabinet into operation and restore power supply.

10. The power supply method according to claim 9, characterized in that, The circuit breaker status signal and the non-electrical protection signals of the transformer and on-load tap changer are output in the form of passive dry contacts, or extended into passive dry contacts via intermediate relays and then connected to the PLC remote station.

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