A demagnetization switch closing circuit for the excitation system of a 300MW unit

Abstract

The utility model discloses a demagnetization switch closing circuit of a 300MW unit excitation system, including a closing delay device, the closing delay device including a closing delay relay SJ, a normally closed contact SJ‑1 of the closing delay relay SJ controlled by the closing delay relay SJ, a normally open contact SJ‑2 of the closing delay relay SJ controlled by the closing delay relay SJ, a closing signal self-holding relay ZJ1, and a normally open contact ZJ1‑1 of the closing signal self-holding relay ZJ1 controlled by the closing signal self-holding relay ZJ1. The technical effect of the utility model is that it can prevent the demagnetization switch closing contactor from jumping when the closing contact is stuck. The utility model can accurately control the closing pulse time, improve the closing reliability of the demagnetization switch, effectively prevent the demagnetization switch from being operated incorrectly, and monitor the operating power supply in real time.

Description

Technical Field

[0001] The utility model relates to a demagnetization switch closing circuit of an excitation system of a 300MW unit. Background Art

[0002] The excitation system is an important part of the automatic control of the generator set. Its performance directly determines the voltage and reactive power regulation of the unit, and the demagnetization switch is one of the important components in the generator excitation circuit. The sensitivity and reliability of the demagnetization switch play a very important role in the normal operation of the generator set. When the generator fails or an accident occurs, if the protection device refuses to operate, or the protection device operates but cannot demagnetize due to poor performance of the demagnetization switch or failure of its control circuit, this will not only cause a certain degree of economic losses to the power system, but may even cause casualties.

[0003] The existing 300MW #1 and #2 units excitation system adopts the self-parallel excitation system of the British Rolls-Royce Company. The three-choice-two selection logic designed by Rolls-Royce is adopted from the excitation regulator to the thyristor rectifier bridge, and the demagnetization switch adopts the MM74 series demagnetization switch produced by the British WB Company. Figure 1 , wherein the demagnetizing switch is controlled by a closing device and a closing control device, and the closing control device is connected to the closing device to control the closing device to close. The closing control device includes a signal source and an intermediate device. The signal source is electrically connected to the intermediate device and sends a closing signal to the intermediate device, and the intermediate device receives the closing signal and drives the closing device to close. The intermediate device includes a closing relay ZJ3 controlled by a closing signal and a normally open contact of the closing relay. After receiving the closing signal, the closing relay ZJ3 controls the normally open contact of the closing relay to close, wherein the normally open contact of the closing relay includes the first normally open contact ZJ3-1 of the closing relay ZJ3, the second normally open contact ZJ3-2 of the closing relay ZJ3 and the third normally open contact ZJ3-3 of the closing relay ZJ3. The purpose of setting multiple normally open contacts of the closing relay here is to prevent the normally open contacts from sticking after long-term use, resulting in the normally open contacts being closed for a long time without control, and then causing the closing device to be connected for a long time. After setting multiple normally open contacts, even if a single normally open contact sticks, the other normally open contacts can still be disconnected normally. The closing device includes a demagnetization switch closing contactor 41CC, which is connected in series after the normally open contact of the closing relay and is connected after the normally open contact of the closing relay is closed, so that the demagnetization switch is closed.

[0004] However, after long-term operation, some problems have gradually emerged in the existing system, including: 1. When the closing contacts become stuck due to long-term operation, the demagnetization switch closing contactor will be in operation all the time, which may easily cause the demagnetization switch closing contactor to overheat and burn. 2. There are no anti-misoperation contacts in the closing control circuit, and there is a possibility of misoperation. 3. The closing control circuit cannot control the closing pulse time, and modifying the closing pulse time requires modifying the thermal logic as a whole, which makes adjustment more difficult. 4. It is impossible to monitor the operating power supply remotely in real time, so it is impossible to detect interruptions in the operating power supply in time, which may cause the demagnetization switch to refuse to operate in the event of an accident. Summary of the invention

[0005] In order to solve the technical problems of the existing self-parallel excitation system, such as the adhesion of closing nodes which may easily lead to contactor burning, the risk of misoperation, the difficulty in adjusting the closing pulse time and the incomplete monitoring, the utility model provides a 300MW unit excitation system demagnetization switch closing circuit to prevent contactor burning, reduce the risk of misoperation, and realize the technical effects of simple and easy control of the closing control circuit and comprehensive monitoring.

[0006] In order to achieve the above technical purpose, the technical solution of the utility model is:

[0007] A 300MW unit excitation system demagnetization switch closing circuit, comprising a closing device and a closing control device, wherein the closing control device is connected to the closing device to control the closing device to close;

[0008] The closing control device includes a signal source and an intermediate device; the signal source is electrically connected to the intermediate device and sends a closing signal to the intermediate device, and the intermediate device receives the closing signal and drives the closing device to close the switch;

[0009] The intermediate device includes a closing relay ZJ3 controlled by a closing signal and a normally open contact of the closing relay. After receiving the closing signal, the closing relay ZJ3 controls the normally open contact of the closing relay to close.

[0010] The closing device includes a demagnetization switch closing contactor 41CC, which is connected in series behind the normally open contact of the closing relay and is turned on after the normally open contact of the closing relay is closed, so that the demagnetization switch is closed;

[0011] It also includes a closing delay device, which includes a closing delay relay SJ, a closing delay relay SJ normally closed contact SJ-1 controlled by the closing delay relay SJ, a closing delay relay SJ normally open contact SJ-2 controlled by the closing delay relay SJ, a closing signal self-holding relay ZJ1, and a closing signal self-holding relay ZJ1 normally open contact ZJ1-1 controlled by the closing signal self-holding relay ZJ1;

[0012] The normally closed contact SJ-1 of the closing delay relay SJ is connected in series between the signal source and the closing relay ZJ3; the closing signal self-holding relay ZJ1 is connected in parallel with the closing relay ZJ3; one end of the normally open contact SJ-2 of the closing delay relay SJ is connected in parallel before the normally closed contact SJ-1 of the closing delay relay SJ, and the other end is connected in series to the closing delay relay SJ; one end of the normally open contact ZJ1-1 of the closing signal self-holding relay ZJ1 is connected to the operating power supply, and the other end is connected to the Between the normally open contact SJ-2 of the closing delay relay SJ and the closing delay relay SJ, and closed after the closing signal self-holding relay ZJ1 is turned on; among them, the normally closed contact SJ-1 of the closing delay relay SJ is delayed to open after the closing delay relay SJ is turned on, and the normally open contact SJ-2 of the closing delay relay SJ is delayed to close after the closing delay relay SJ is turned on, and the delay length of the normally closed contact SJ-1 of the closing delay relay SJ and the normally open contact SJ-2 of the closing delay relay SJ are the same.

[0013] The demagnetization switch closing circuit of the 300MW unit excitation system also includes a normally open contact ZJ4-1 of the opening relay ZJ; the normally closed contact ZJ4-1 of the opening relay ZJ4 is connected in series between the signal source and the normally closed contact SJ-1 of the closing delay relay SJ, and is controlled by the opening relay ZJ4 to be turned off when the opening relay ZJ4 is turned on.

[0014] The described 300MW unit excitation system demagnetization switch closing circuit also includes a normally closed contact ZJ6-1 of the opening relay ZJ6; the described normally closed contact ZJ6-1 of the opening relay ZJ6 is connected in series between the signal source and the normally closed contact SJ-1 of the closing delay relay SJ, and is controlled by the opening relay ZJ6 to be turned off when the opening relay ZJ6 is turned on.

[0015] The demagnetization switch closing circuit of the 300MW unit excitation system also includes a demagnetization switch normally closed auxiliary contact 41b-1; the demagnetization switch normally closed auxiliary contact 41b-1 is connected in series between the signal source and the normally closed contact SJ-1 of the closing delay relay SJ, and is turned off after the demagnetization switch is closed.

[0016] The demagnetization switch closing circuit of the excitation system of a 300MW unit also includes a power supply monitoring circuit. The operating power supply monitoring circuit includes an operating power supply monitoring relay XJ3. Both ends of the operating power supply monitoring relay XJ3 are connected to the operating power supply and are used to control the normally closed contacts of the operating power supply monitoring relay XJ3 arranged in the monitoring room. The normally closed contacts of the operating power supply monitoring relay XJ3 are connected to the alarm circuit of the monitoring room and are closed after the operating power supply monitoring relay XJ3 is powered off, thereby connecting the alarm circuit to issue an alarm.

[0017] The demagnetization switch closing circuit of the excitation system of a 300MW unit, the signal source includes a manual closing button and a remote closing command signal source connected in parallel.

[0018] The technical effect of the utility model is that it can prevent the demagnetization switch closing contactor from jumping when the closing contacts are stuck. The utility model can accurately control the closing pulse time, improve the closing reliability of the demagnetization switch, effectively prevent misoperation of the demagnetization switch, and monitor the operating power supply in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the closing circuit of the demagnetizing switch of the original 300MW unit excitation system.

[0020] Figure 2 The utility model provides a schematic diagram of a closing circuit of a demagnetization switch of an excitation system of a 300MW unit.

[0021] Among them, 1 is the closing relay ZJ3, 2 is the closing signal self-holding relay ZJ1, 3 is the closing delay relay SJ, 4 is the closing delay relay normally closed contact SJ-1, 5 is the closing delay relay normally open contact SJ-2, 6 is the remote closing command signal source, 7 is the manual closing button 60KK, 8 is the demagnetization switch normally closed auxiliary contact 41b-1, 9 is the A, C cabinet, centralized control console emergency opening relay normally closed contact ZJ6-1, 10 is the normally closed contact ZJ4-1 of the B cabinet and ECS opening relay, 11 is the normally open contact ZJ1-1 of the closing signal self-holding relay, 12 is the normally open contact ZJ3-1 of the first closing relay ZJ3, 13 is the normally open contact ZJ3-2 of the second closing relay ZJ3, 14 is the normally open contact ZJ3-3 of the third closing relay ZJ3, 15 is the demagnetization switch closing contactor 41CC, and 16 is the operating power supply monitoring relay XJ3. DETAILED DESCRIPTION

[0022] See also Figure 2In this embodiment, a closing delay circuit is set in the closing control circuit, and the closing delay circuit is composed of a closing delay relay SJ, a closing signal self-holding relay ZJ1, a normally open contact ZJ1-1 of the closing signal self-holding relay ZJ1, a normally closed contact SJ-1 that is delayed to open after the closing delay relay SJ is energized, and a normally open contact SJ-2 that is delayed to close after the closing delay relay SJ is energized. The closing delay circuit can accurately control the duration of the demagnetization switch closing pulse, improve the closing reliability of the demagnetization switch, and control the delay to disconnect the closing circuit by the demagnetization switch closing contactor 41CC with arc extinguishing ability, so as to avoid disconnecting the closing circuit by the normally open contact ZJ3-1 of the first closing relay ZJ3, the normally open contact ZJ3-2 of the second closing relay ZJ3, and the normally open contact ZJ3-3 of the third closing relay ZJ3, thereby improving the service life of the ZJ3 relay. In this embodiment, a closing delay relay SJ and a closing signal self-holding relay ZJ1 are newly added to the closing control circuit; a normally closed contact SJ-1 is connected from contact No. 8 and contact No. 5 of the closing delay relay SJ; a normally open contact SJ-2 is connected from contact No. 1 and contact No. 3 of the closing delay relay SJ; a normally open contact ZJ1-1 is connected from contact No. 6 and contact No. 3 of the closing signal self-holding relay ZJ1; SJ, SJ-1, SJ-2, ZJ1, and ZJ1-1 are connected to the closing control circuit to form a closing delay circuit.

[0023] In this embodiment, a normally open contact SJ-2 is set in the closing control circuit, which is delayed to close after the closing delay relay SJ is energized. In cooperation with the closing delay relay SJ, it can prevent the closing contact of the demagnetizing switch (local closing or remote DCS closing) from sticking when the demagnetizing switch is in the open position. The demagnetizing switch refuses to operate due to a mechanism failure, causing the demagnetizing switch closing contactor 41CC to jump, resulting in the demagnetizing switch closing contactor 41CC being burned due to frequent operation. When the closing contact is stuck, the closing control circuit is connected to link the demagnetizing switch closing contactor 41CC to close. At this time, the demagnetizing switch refuses to operate due to a mechanism failure, resulting in a closing failure; after the first closing failure, SJ and SJ-2 form a self-holding, and SJ is always in an action state, causing SJ-1 to be powered on and delayed to disconnect, the closing control circuit is blocked, and the demagnetizing switch closing contactor 41CC will not be attracted again. In this embodiment, the normally open contact SJ-2 is connected from the No. 1 contact and the No. 3 contact of the closing delay relay SJ. Therefore, the closing time is controlled by the delay node, avoiding the problem of modifying the thermal logic as a whole and making the closing time control easier.

[0024] In this embodiment, a normally closed auxiliary contact 41b-1 of a demagnetizing switch is also provided in the closing control circuit, and the normally closed auxiliary contact 41b-1 is connected from the contacts 72D-23 and 72D-24 of the demagnetizing switch. When the demagnetizing switch is in the closing position, the closing control circuit is disconnected to prevent repeated sending of closing instructions.

[0025] In this embodiment, the normally open contact ZJ4-1 of the opening relay ZJ4 and the normally open contact ZJ6-1 of the opening relay ZJ6 are set in the closing control circuit. When there is a tripping instruction, the closing control circuit is disconnected to prevent the closing instruction from being mistakenly issued at this time. The normally open contact ZJ4-1 is connected from the No. 3 and No. 7 contacts of the opening relay ZJ4, and the normally open contact ZJ6-1 is connected from the No. 3 and No. 7 contacts of the opening relay ZJ6, so that ZJ4-1 and ZJ6-1 are connected to the closing control circuit. Among them, the normally closed contact ZJ6-1 of the emergency opening relay of the A, C cabinets and the centralized control console is controlled by the A, C cabinets and the centralized control console, and the normally closed contact ZJ4-1 of the opening relay of the B cabinet and the ECS is controlled by the B cabinet and the ECS opening, thereby introducing the control logic of other positions in the system to prevent misoperation.

[0026] In this embodiment, an operation power monitoring circuit is added, which includes an operation power monitoring relay XJ3, both ends of which are connected to the operation power, and are used to control the normally closed contact of the operation power monitoring relay XJ3 set in the monitoring room, and the normally closed contact of the operation power monitoring relay XJ3 is connected to the alarm circuit in the monitoring room, and is closed after the operation power monitoring relay XJ3 is powered off, so that the alarm circuit is connected to sound an alarm, so as to realize real-time monitoring of the operation power, timely discover the operation power failure, and prevent the demagnetization switch from refusing to operate in the event of an operation power failure.

Claims

1. A 300MW unit excitation system demagnetization switch closing circuit, comprising a closing device and a closing control device, wherein the closing control device is connected to the closing device to control the closing device to close; The closing control device includes a signal source and an intermediate device; the signal source is electrically connected to the intermediate device and sends a closing signal to the intermediate device, and the intermediate device receives the closing signal and drives the closing device to close the circuit; The intermediate device includes a closing relay ZJ3 controlled by a closing signal and a normally open contact of the closing relay. After receiving the closing signal, the closing relay ZJ3 controls the normally open contact of the closing relay to close. The closing device includes a demagnetization switch closing contactor 41CC, which is connected in series behind the normally open contact of the closing relay and is turned on after the normally open contact of the closing relay is closed, so that the demagnetization switch is closed; It is characterized in that It also includes a closing delay device, which includes a closing delay relay SJ, a closing delay relay SJ normally closed contact SJ-1 controlled by the closing delay relay SJ, a closing delay relay SJ normally open contact SJ-2 controlled by the closing delay relay SJ, a closing signal self-holding relay ZJ1, and a closing signal self-holding relay ZJ1 normally open contact ZJ1-1 controlled by the closing signal self-holding relay ZJ1; The normally closed contact SJ-1 of the closing delay relay SJ is connected in series between the signal source and the closing relay ZJ3; the closing signal self-holding relay ZJ1 is connected in parallel with the closing relay ZJ3; one end of the normally open contact SJ-2 of the closing delay relay SJ is connected in parallel before the normally closed contact SJ-1 of the closing delay relay SJ, and the other end is connected in series to the closing delay relay SJ; one end of the normally open contact ZJ1-1 of the closing signal self-holding relay ZJ1 is connected to the operating power supply, and the other end is connected to the Between the normally open contact SJ-2 of the closing delay relay SJ and the closing delay relay SJ, and closed after the closing signal self-holding relay ZJ1 is turned on; among them, the normally closed contact SJ-1 of the closing delay relay SJ is delayed to open after the closing delay relay SJ is turned on, and the normally open contact SJ-2 of the closing delay relay SJ is delayed to close after the closing delay relay SJ is turned on, and the delay length of the normally closed contact SJ-1 of the closing delay relay SJ and the normally open contact SJ-2 of the closing delay relay SJ are the same.

2. A 300MW unit excitation system demagnetization switch closing circuit according to claim 1, characterized in that: It also includes a normally open contact and a normally closed contact ZJ4-1 of the opening relay ZJ; the normally closed contact ZJ4-1 of the opening relay ZJ4 is connected in series between the signal source and the normally closed contact SJ-1 of the closing delay relay SJ, and is controlled by the opening relay ZJ4 to be turned off when the opening relay ZJ4 is turned on.

3. A 300MW unit excitation system demagnetization switch closing circuit according to claim 1, characterized in that: It also includes a normally closed contact ZJ6-1 of the opening relay ZJ6; the normally closed contact ZJ6-1 of the opening relay ZJ6 is connected in series between the signal source and the normally closed contact SJ-1 of the closing delay relay SJ, and is controlled by the opening relay ZJ6 to be turned off when the opening relay ZJ6 is turned on.

4. A 300MW unit excitation system demagnetization switch closing circuit according to claim 1, characterized in that: It also includes a demagnetization switch normally closed auxiliary contact 41b-1; the demagnetization switch normally closed auxiliary contact 41b-1 is connected in series between the signal source and the normally closed contact SJ-1 of the closing delay relay SJ, and is turned off after the demagnetization switch is closed.

5. A 300MW unit excitation system demagnetization switch closing circuit according to claim 1, characterized in that: It also includes a power supply monitoring circuit, the operating power supply monitoring circuit includes an operating power supply monitoring relay XJ3, both ends of the operating power supply monitoring relay XJ3 are connected to the operating power supply, and are used to control the normally closed contacts of the operating power supply monitoring relay XJ3 arranged in the monitoring room, the normally closed contacts of the operating power supply monitoring relay XJ3 are connected to the alarm circuit of the monitoring room, and are closed after the operating power supply monitoring relay XJ3 is powered off, thereby connecting the alarm circuit to sound an alarm.

6. A 300MW unit excitation system demagnetization switch closing circuit according to claim 1, characterized in that: The signal source comprises a manual closing button and a remote closing command signal source connected in parallel.

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