Automatic field suppression device and excitation system

Abstract

The utility model relates to the technical field of excitation systems, in particular to an automatic field suppression device and an excitation system, comprising a primary excitation power supply which is electrically connected with a generator rotor according to a current output direction; the de-excitation loop comprises a de-excitation switch and a de-excitation resistor which are sequentially connected between the positive electrode and the negative electrode of the primary excitation power supply, and the de-excitation resistor is connected with the generator rotor in parallel; and the overvoltage protection loop is connected in parallel with the de-excitation resistor and comprises an overvoltage jumper and an overvoltage resistor which are connected in sequence. According to the utility model, the primary excitation power supply, the field suppression circuit and the overvoltage protection circuit are used in cooperation, overvoltage protection can be provided for the field suppression circuit, the reset button is used in cooperation with the remote / local control module, manual reset is realized, and the problem of remote and local control switching is solved.

Description

Technical Field

[0001] This utility model relates to the field of excitation system technology, and in particular to an automatic demagnetizing device and excitation system. Background Technology

[0002] The excitation system is a crucial component of a generator, providing adjustable excitation current to meet the needs of normal generator operation and safe power system operation. Therefore, regulating and controlling the generator's excitation not only ensures the reliability, safety, and stability of the generator and power system, but also improves their technical and economic indicators.

[0003] Demagnetization technology is applied when a short circuit occurs inside the generator, the main transformer, or between the generator and the load switch. Simultaneously with the tripping of the relay protection, the demagnetization system is activated to cut off the generator's excitation power and quickly dissipate the energy stored in the excitation windings. This causes the rotor current to decay rapidly, quickly reducing the generator's electromotive force and short-circuit current, thereby minimizing the possibility of damage to the generator or transformer, such as insulation burnout, conductor melting, or core burnout, or the escalation of the accident. However, current technologies are inconvenient for circuit protection after demagnetization is initiated, especially since the demagnetization start-up control method is limited to local operation and lacks remote automatic control capabilities. Utility Model Content

[0004] In this section, as well as in the abstract and title of this application, some simplifications or omissions may be made to avoid obscuring the purpose of this section, the abstract, and the title of this application. Such simplifications or omissions shall not be used to limit the scope of this utility model.

[0005] To address the shortcomings of existing technologies, one objective of this utility model is to provide an automatic demagnetizing device.

[0006] To achieve the above objectives, this utility model adopts the following technical solution: an automatic demagnetizing device, comprising,

[0007] The primary excitation power supply is electrically connected to the generator rotor in the direction of current output;

[0008] The demagnetizing circuit includes a demagnetizing switch and a demagnetizing resistor connected sequentially between the positive and negative terminals of the primary excitation power supply, wherein the demagnetizing resistor is connected in parallel with the generator rotor; and...

[0009] The overvoltage protection circuit, which is connected in parallel with the demagnetizing resistor, includes an overvoltage jumper and an overvoltage resistor connected in sequence.

[0010] As a preferred embodiment of the automatic demagnetizing device of this utility model, the overvoltage protection circuit is provided in at least two sets, and the at least two sets of the overvoltage protection circuit are respectively provided on both sides of the demagnetizing switch.

[0011] In a preferred embodiment of the automatic demagnetizing device of this utility model, the overvoltage jumper includes an avalanche diode and a thyristor connected in series with the overvoltage resistor.

[0012] In a preferred embodiment of the automatic demagnetizing device of this utility model, the overvoltage jumper further includes an overvoltage triggering circuit connected in parallel with the overvoltage resistor.

[0013] The overvoltage triggering circuit includes overvoltage triggers connected in series, and an indicator light facing outwards from the demagnetizing cabinet.

[0014] In a preferred embodiment of the automatic demagnetizing device described in this utility model, the overvoltage jumper further includes a reset button connected in parallel with the demagnetizing resistor and positioned facing outwards from the demagnetizing cabinet.

[0015] The reset button has one normally open contact and one normally closed contact.

[0016] In a preferred embodiment of the automatic demagnetizing device of this utility model, the initial excitation power supply includes an initial excitation circuit one configured with AC power or an initial excitation circuit two configured with DC power.

[0017] The primary excitation circuit has a rectifier that converts alternating current into direct current.

[0018] As a preferred embodiment of the automatic demagnetizing device described in this utility model, it further includes a remote / local control module located inside the demagnetizing cabinet.

[0019] The remote / local control module includes a remote / local switching handle connected to the demagnetization circuit and a handle for opening / closing the demagnetization switch.

[0020] The remote / local switching handle has one normally open node and one normally closed node.

[0021] The normally open contact of the remote / local switching handle is connected to the remote position of the demagnetizing cabinet.

[0022] To address the shortcomings of existing technologies, another objective of this invention is to provide an excitation system.

[0023] To achieve the above objectives, this utility model adopts the following technical solution: an excitation system, including the aforementioned automatic demagnetizing device, and...

[0024] The excitation regulating unit located in the regulating cabinet includes an excitation regulator that controls the initial excitation power supply;

[0025] The power rectifier unit located in the rectifier cabinet includes a fan located in the rectifier cabinet and a rectifier circuit for maintaining voltage stability.

[0026] As a preferred embodiment of the excitation system of this utility model, the rectifier circuit includes a rectifier bridge, a resistor-capacitor absorption circuit and an overvoltage absorption circuit connected in sequence, and the AC side of the resistor-capacitor absorption circuit and the overvoltage absorption circuit is provided with a fast-acting fuse.

[0027] As a preferred embodiment of the excitation system of this utility model, the fan is provided in two sets, and the power rectifier unit further includes a fan control circuit for automatically switching between the two sets of fans.

[0028] The beneficial effects of this utility model are as follows: By using the initial excitation power supply, demagnetizing circuit and overvoltage protection circuit in combination, this utility model can provide overvoltage protection for the demagnetizing circuit. By setting a reset button and using it in conjunction with the remote / local control module, manual reset can be achieved, thus solving the problem of switching between remote and local control. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram illustrating the composition and structural principle of the automatic demagnetizing device of this utility model.

[0031] Figure 2 This is a schematic diagram of the composition and structure of the overvoltage jumper of the automatic demagnetizing device of this utility model.

[0032] Figure 3 This is a schematic diagram of the structure of the reset button of the automatic demagnetizing device of this utility model.

[0033] Figure 4 This is a schematic diagram of the composition of the remote / local control module of the automatic demagnetizing device of this utility model.

[0034] Figure 5 This is a schematic diagram of the composition principle and structure of the excitation system of this utility model.

[0035] Figure 6 This is a schematic diagram of the composition and structure of the rectifier circuit of the excitation system of this utility model.

[0036] Figure 7 This is a schematic diagram of the composition and structure of the fan control circuit of the excitation system of this utility model.

[0037] Figure 8 This is a schematic diagram of the control structure of the dual-fan excitation system of this utility model. Detailed Implementation

[0038] To make the objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0039] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0040] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments.

[0041] Example 1

[0042] Reference Figure 1 and Figure 2 This is the first embodiment of the present invention. This embodiment provides an automatic demagnetizing device that can provide overvoltage protection for the demagnetizing circuit. It includes: a primary excitation power supply 100, a demagnetizing circuit 200, and an overvoltage protection circuit 300. The primary excitation power supply 100 is equipped with an AC or DC primary excitation circuit for the self-excited generator. The regulator can control the primary excitation contactor to enable or disable the primary excitation. By setting the demagnetizing circuit 200 and the overvoltage protection circuit 300, the excitation is quickly cut off when the generator fails, consuming the magnetic field energy stored in the generator to protect the generator and excitation equipment.

[0043] Specifically, the primary excitation power supply 100 is electrically connected to the generator rotor in the direction of current output. The demagnetizing circuit 200 includes a demagnetizing switch 201 and a demagnetizing resistor 202 connected sequentially between the positive and negative terminals of the primary excitation power supply 100. The demagnetizing resistor 202 is connected in parallel with the generator rotor. The overvoltage protection circuit 300 is connected in parallel with the demagnetizing resistor 202 and includes an overvoltage jumper 301 and an overvoltage resistor 302 connected sequentially. The overvoltage jumper 301 is used for grid protection, power system protection, etc., and can identify different types of overvoltages. The overvoltage jumper 301 includes an avalanche diode and a thyristor connected in series with the overvoltage resistor 302. When an overvoltage occurs, the avalanche diode conducts. When the avalanche diode conducts, the thyristor is triggered to connect the demagnetizing resistor 202 in parallel with the generator rotor. In this embodiment, the existing DGA-230-3P overvoltage jumper 301 and ZnO overvoltage resistor can be used to form the overvoltage protection circuit 300.

[0044] Furthermore, at least two sets of overvoltage protection circuits 300 are provided, and the at least two sets of overvoltage protection circuits 300 are respectively located on both sides of the demagnetizing switch 201, which can realize overvoltage protection on the rotor side and the power supply side respectively. The primary excitation power supply 100 includes a primary excitation circuit one 101 configured with AC power or a primary excitation circuit two 102 configured with DC power. The primary excitation circuit one 101 has a rectifier 101a that converts AC power into DC power. In this embodiment, the rectifier 101a is a three-phase rectifier, which can meet the input of AC power and DC power. The demagnetizing switch 201 is a DC demagnetizing switch, and the demagnetizing resistor 202 is a ZnO demagnetizing resistor. When triggered, the demagnetizing switch 201 trips to cut off the rotor power supply circuit, and at the same time, the demagnetizing resistor 202 is turned on to force the rotor current to flow through the demagnetizing resistor 202.

[0045] Preferably, the overvoltage jumper 301 further includes an overvoltage triggering circuit connected in parallel with the overvoltage resistor 302. The overvoltage triggering circuit includes an overvoltage trigger 301c-1 connected in series and an indicator light 301c-2 facing outwards from the demagnetizing cabinet. In this embodiment, the overvoltage trigger 301c-1 uses TI's overvoltage protection IC: bq24380. The indicator light 301c-2 and the overvoltage trigger 301c-1 form an overvoltage triggering circuit. When the circuit is connected, the indicator light 301c-2 lights up as a warning.

[0046] In summary, by using the initial excitation power supply 100, the demagnetizing circuit 200, and the overvoltage protection circuit 300 together, overvoltage protection for the demagnetizing circuit can be achieved.

[0047] Example 2

[0048] Reference Figures 1-4This is the second embodiment of the present invention. Unlike the previous embodiment, this embodiment provides a reset button 301d and a remote / local control module 400, which enables the switching of multiple control modes.

[0049] Specifically, the overvoltage jumper 301 also includes a reset button 301d connected in parallel with the demagnetizing resistor 202 and facing outwards from the demagnetizing cabinet. The reset button 301d has one normally open contact and one normally closed contact. When the reset button 301d is pressed, the normally open contact closes and the normally closed contact opens, forming a circuit across the capacitor and short-circuiting it. Therefore, during the button press, the capacitor begins to release the previously charged charge. After triggering the demagnetizing circuit 200, the reset button 301d can be pressed to restore the circuit.

[0050] Furthermore, it also includes a remote / local control module 400 located inside the demagnetizing cabinet. The remote / local control module 400 includes a remote / local switching handle 401 connected to the demagnetizing circuit 200 and a tripping / closing handle 402 for controlling the demagnetizing switch 201. The demagnetizing cabinet is equipped with a PLC controller. A PLC is an electronic device designed specifically for industrial environments, used as a digital logic controller for automated control. This embodiment uses an S7-1200 model PLC controller, which is suitable for various industrial control applications. A long pulse signal is sent remotely via the DCS, and then the PLC controller triggers the demagnetizing circuit 200 to achieve remote closing. A DCS (Distributed Control System) is a collection of control devices distributed in different field locations. These devices are connected through a data communication network to form an integrated automated control system. The DCS system mainly consists of remote input / output modules (RIO), controllers, operator stations, and communication networks. This embodiment uses a JX-300XP model DCS system, which applies the latest signal processing technology, high-speed network communication technology, software platform and software design technology, and fieldbus technology. After the DCS remotely stops sending pulse signals, the PLC controller triggers the reset button 301d to remotely open the circuit. In this embodiment, an operation panel is provided on the outside of the demagnetizing cabinet, which is equipped with a handle for opening and closing the demagnetizing switch 201. The demagnetizing switch 201 can be opened and closed locally. In the DCS system, the demagnetizing switch 201 can be opened and closed remotely by clicking the open / close button.

[0051] Preferably, the remote / local switching handle 401 has one normally open contact and one normally closed contact. The normally open contact of the remote / local switching handle 401 is connected to a remote location within the demagnetizing cabinet. The remote / local switching handle 401 is located inside the demagnetizing cabinet. When the normally open contact is activated, the demagnetizing circuit 200 can be triggered remotely. When the normally closed contact is activated, remote control is disabled, and triggering can only be performed locally.

[0052] The rest of the structure is the same as in Example 1.

[0053] In summary, by using the reset button 301d in conjunction with the remote / local control module 400, manual reset can be achieved, and the problem of switching between remote and local control can be solved.

[0054] Example 3

[0055] Reference Figures 1-8 This is the third embodiment of the present invention. Unlike the previous embodiment, this embodiment provides an excitation system, including an automatic demagnetizing device, an excitation regulating unit 500 located in a regulating cabinet (including an excitation regulator for controlling the primary excitation power supply 100), and a power rectifier unit 600 located in a rectifier cabinet (including a fan 601 and a rectifier circuit 602 for maintaining voltage stability). By collecting analog and status signals, the system determines changes in generator operating conditions, adjusts the trigger pulse angle of the rectifier bridge, and controls the generator excitation current to meet the generator's operational needs.

[0056] Furthermore, the rectifier circuit 602 includes a rectifier bridge 602a, an RC snubber circuit 602b, and an overvoltage snubber circuit 602c connected in sequence. A fast-acting fuse 602d is provided on the AC side of both the RC snubber circuit 602b and the overvoltage snubber circuit 602c. The main circuit AC side of the rectifier circuit 602 is equipped with a fast-acting fuse 602d. In this embodiment, RS0 or RS3 series fast-acting fuses are selected, which can provide overcurrent protection for components. When the fuse blows, the microswitch operates, and the signal circuit indicates a fault signal. The operation of the rectifier circuit 602 is controlled by a "pulse switching" signal. When the rectifier circuit 602 malfunctions and needs to be taken out of service, the pulse switch can be cut off first, and the AC / DC disconnector can be opened only after confirming that the current has dropped to 0. When the rectifier circuit 602 needs to be put back into operation after maintenance, the AC / DC disconnector can be closed first, and then the pulse switch can be activated.

[0057] The fan 601 is provided in two sets, and the power rectifier unit 600 also includes a fan control circuit 603 for automatically switching between the two sets of fans 601. Figure 8Switches 1-2 and 3-4 control the main power supply. Switch KZD23-25 ​​controls the start of one of the fans 601, and switch KZD24-26 controls the start of the other fan 601. During normal operation, one fan 601 is powered by default. If one fan 601 loses power, it automatically switches to the second power supply. Fan 601 can be switched via fan control circuit 603. It is recommended to operate only one fan 601 during normal operation. If one fan 601 fails, it will automatically switch to another group of fans. When a rectifier cabinet is disconnected, the remaining rectifier cabinets can operate with two fans. Fan control circuit 603 can be selected for automatic or manual control. In manual mode, fan 601 starts without being controlled by the excitation regulator; it starts as soon as power is supplied. In automatic mode, fan 601 starts under the control of the excitation regulator, requiring one of the following conditions to be met: a remote excitation command, a terminal voltage greater than a threshold value, or an excitation current greater than a threshold value.

[0058] The rest of the structure is the same as in Example 2.

[0059] It should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. An automatic demagnetizing device (M), characterized in that: Including those separately located in the demagnetizing cabinet, The primary excitation power supply (100) is electrically connected to the generator rotor in the direction of current output; The demagnetizing circuit (200) includes a demagnetizing switch (201) and a demagnetizing resistor (202) connected sequentially between the positive and negative terminals of the primary excitation power supply (100), wherein the demagnetizing resistor (202) is connected in parallel with the generator rotor; and, An overvoltage protection circuit (300) is connected in parallel with a demagnetizing resistor (202) and includes an overvoltage jumper (301) and an overvoltage resistor (302) connected in sequence.

2. The automatic demagnetizing device (M) as described in claim 1, characterized in that: The overvoltage protection circuit (300) is provided in at least two sets, and the at least two sets of the overvoltage protection circuit (300) are respectively located on both sides of the demagnetizing switch (201).

3. The automatic demagnetizing device (M) as described in claim 1 or 2, characterized in that: The overvoltage jumper (301) includes an avalanche diode and a thyristor connected in series with the overvoltage resistor (302).

4. The automatic demagnetizing device (M) as described in claim 3, characterized in that: The overvoltage jumper (301) also includes an overvoltage trigger circuit connected in parallel with the overvoltage resistor (302). The overvoltage triggering circuit includes an overvoltage trigger (301c-1) connected in series, and an indicator light (301c-2) facing outwards from the demagnetizing cabinet.

5. The automatic demagnetizing device (M) as described in claim 4, characterized in that: The overvoltage jumper (301) also includes a reset button (301d) connected in parallel with the demagnetizing resistor (202) and facing outwards from the demagnetizing cabinet. The reset button (301d) has one normally open contact and one normally closed contact.

6. The automatic demagnetizing device (M) as described in any one of claims 1-2 and 4-5, characterized in that: The primary excitation power supply (100) includes a primary excitation circuit one (101) configured with AC power or a primary excitation circuit two (102) configured with DC power. The primary excitation circuit (101) has a rectifier (101a) that converts alternating current into direct current.

7. The automatic demagnetizing device (M) as described in any one of claims 1-2 and 4-5, characterized in that: It also includes a remote / local control module (400) located inside the demagnetizing cabinet. The remote / local control module (400) includes a remote / local switching handle (401) connected to the demagnetizing circuit (200) and a circuit breaker opening / closing handle (402) for controlling the demagnetizing switch (201). The remote / local switching handle (401) has one normally open node and one normally closed node. The normally open terminal of the remote / local switching handle (401) is connected to the remote position of the demagnetizing cabinet.

8. An excitation system, characterized in that: Including the automatic demagnetizing device (M) as described in claim 1, and, The excitation regulating unit (500) located in the regulating cabinet includes an excitation regulator that controls the initial excitation power supply (100); The power rectifier unit (600) located in the rectifier cabinet includes a fan (601) located in the rectifier cabinet and a rectifier circuit (602) for maintaining voltage stability.

9. The excitation system as described in claim 8, characterized in that: The rectifier circuit (602) includes a rectifier bridge (602a), a resistor-capacitor absorption circuit (602b), and an overvoltage absorption circuit (602c) connected in sequence. The AC side of the resistor-capacitor absorption circuit (602b) and the overvoltage absorption circuit (602c) is provided with a fast-acting fuse (602d).

10. The excitation system as described in claim 8 or 9, characterized in that: The fan (601) is provided in two sets, and the power rectifier unit (600) also includes a fan control circuit (603) for automatically switching between the two sets of fans (601).

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