Boiler trip relay control circuit
By designing a boiler trip relay control circuit and utilizing a series-parallel structure of a multiple-out-of-two logic control circuit and a trip relay, the problems of false tripping and failure to trip during power failures in the DCS system were solved, thus achieving reliability and safety in boiler trip control.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CENT SOUTHERN CHINA ELECTRIC POWER DESIGN INST CHINA POWER ENG CONSULTING GROUP CORP
- Filing Date
- 2025-06-19
- Publication Date
- 2026-06-23
Smart Images
Figure CN224401150U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of thermal power generation technology, specifically to a boiler trip relay control circuit. Background Technology
[0002] In the design of instrumentation and control systems in thermal power plants, the boiler main fuel trip (MFT) protection function is implemented by the DCS control system during normal unit operation. Simultaneously, the boiler hard MFT control loop serves as a backup in case of DCS system failures (such as power supply failures or controller failures). A well-designed boiler hard MFT control loop can effectively improve control reliability and ensure the safety of key equipment.
[0003] The main design scheme of the boiler hard MFT control circuit is set up according to the energized operation mode of two sets of trip relays. That is, when the trip relay of any circuit is energized, the normally open contact of the trip relay closes (called normally open contact) and the normally closed contact opens (called normally closed contact). At this time, the relevant object is activated to achieve the purpose of stopping and protecting the boiler.
[0004] When using the normally open contact of the relay in the boiler furnace protection system trip output card, in order to trigger the trip relay of the boiler hard MFT control circuit when a power failure occurs in the DCS system, it is necessary to connect the normally closed contact signal of the DCS system power monitoring relay. This signal combination is complex and there is a possibility of false tripping or failure to trip in the boiler hard MFT control circuit.
[0005] Therefore, properly configuring the control circuit of the trip relay can improve the reliability of boiler trip control. Summary of the Invention
[0006] In view of this, the present application provides a boiler trip relay control circuit that can improve the reliability of the trip input signal, thereby achieving reliable control of the trip relay and ensuring the safety of the boiler.
[0007] This application provides a boiler trip relay control circuit, including a boiler furnace protection system, a multiple-out-of-two logic control circuit, and a trip relay;
[0008] The boiler furnace protection system includes multiple independent switch trip output cards. Each switch trip output card is equipped with a first normally closed switch trip output contact. The trip signal output terminal of the boiler furnace protection system is connected to each of the first normally closed switch trip output contacts. The multiple-out-of-two logic control circuit includes trip signal relays corresponding one-to-one with the first normally closed switch trip output contacts. The coil of the trip signal relay is connected in series between the first normally closed switch trip output contact and the power supply line of the control circuit. The multiple-out-of-two logic control circuit includes several parallel communication channels. Each communication channel is connected in series with the normally open contacts of any two trip signal relays. The multiple switch trip output cards of the boiler furnace protection system are connected to the boiler main fuel trip control circuit using normally closed relay contacts to trigger the trip relays of the boiler main fuel trip control circuit when the unit DCS power supply fails.
[0009] In one embodiment, the device further includes a button unit, which includes a first button and a second button. The two sets of normally open contacts of the first button are connected in parallel, and the two sets of normally open contacts of the second button are connected in parallel. The normally open contacts of the first button and the normally open contacts of the second button are connected in series to the coil terminal of the trip relay.
[0010] In one embodiment, the boiler furnace protection system switch trip output card is further provided with a normally open switch output contact. The reset signal output terminal of the boiler furnace protection system is connected to the normally open switch output contact, and the normally open switch output contact is connected to two parallel relay contacts of the trip relay.
[0011] In one embodiment, a power monitoring relay is further included, wherein the normally closed contact of the power monitoring relay is connected to the alarm signal input terminal of the DCS control system.
[0012] In one embodiment, the multiple-out-of-two logic control circuit is a three-out-of-two logic circuit, which includes three trip signal relays. The three-out-of-two logic circuit includes three parallel communication channels, and each communication channel is connected in series with the normally open contacts of any two trip signal relays.
[0013] In one embodiment, the trip relay includes a plurality of trip relay coils connected in parallel.
[0014] The boiler trip relay control circuit of this application embodiment includes a boiler furnace protection system, a multi-out-of-two logic control circuit, and a trip relay. The boiler furnace protection system includes multiple independent switch trip output cards, each of which has a first normally closed switch trip output contact. The trip signal output terminal of the boiler furnace protection system is connected to each of the first normally closed switch trip output contacts. The multi-out-of-two logic control circuit includes trip signal relays corresponding one-to-one with the first normally closed switch trip output contacts. The coil of the trip signal relay is connected in series between the first normally closed switch trip output contact and the control circuit power line. The multi-out-of-two logic control circuit includes several parallel communication channels. Each communication channel is connected in series with the normally open contacts of any two trip signal relays. The multiple switch trip output cards of the boiler furnace protection system are connected to the boiler main fuel trip control circuit using normally closed relay contacts to trigger the trip relay of the boiler main fuel trip control circuit when the unit DCS power supply fails. The control circuit of the trip relay is simplified, and the reliability of the trip input signal of the boiler hard MFT circuit is improved, thereby realizing reliable control of the trip relay and ensuring the safety of the boiler. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of this application, 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0016] Figure 1 This is a schematic diagram of the connection of a boiler trip relay control circuit provided in an embodiment of this application. Detailed Implementation
[0017] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.
[0018] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.
[0019] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0020] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.
[0021] like Figure 1 As shown, the boiler trip relay control circuit provided in this application embodiment includes a boiler furnace protection system, a multiple-out-of-two logic control circuit, and a trip relay.
[0022] The boiler furnace protection system includes multiple independent switch trip output cards. Each switch trip output card has a first normally closed switch trip output contact. The trip signal output terminal of the boiler furnace protection system is connected to each first normally closed switch trip output contact. The multiple-choice logic control circuit includes trip signal relays that correspond one-to-one with the first normally closed switch trip output contacts. The coil of the trip signal relay is connected in series between the first normally closed switch trip output contact and the power supply line of the control circuit. The multiple-choice logic control circuit includes several parallel communication channels. Each communication channel is connected in series with the normally open contacts of any two trip signal relays. The multiple switch trip output cards of the boiler furnace protection system are connected to the boiler main fuel trip control circuit through the normally closed contacts of the relays to trigger the trip relays of the boiler main fuel trip control circuit when the unit DCS power supply fails.
[0023] In one embodiment, the device further includes a button unit, which includes a first button and a second button. The two sets of normally open contacts of the first button are connected in parallel, and the two sets of normally open contacts of the second button are connected in parallel. The normally open contacts of the first button and the normally open contacts of the second button are connected in series to the coil terminal of the trip relay.
[0024] In one embodiment, the switch trip output card is further provided with a normally open switch output contact. The reset signal output terminal of the boiler furnace protection system is connected to the normally open switch output contact, and the normally open switch output contact is connected to two parallel relay contacts of the trip relay.
[0025] In one embodiment, a power monitoring relay is also included, the normally closed contact of which is connected to the alarm signal input terminal of the DCS control system.
[0026] In one embodiment, the multiple-out-of-two logic control circuit is a three-out-of-two logic circuit, which includes three trip signal relays. The three-out-of-two logic circuit includes three parallel communication channels, and each communication channel is connected in series with the normally open contacts of any two trip signal relays.
[0027] In one embodiment, the trip relays include a plurality of relays connected in parallel.
[0028] In the application, the control circuit uses a 110V DC power supply. The boiler furnace protection system (FSS system), a subsystem of the DCS control system, outputs three relay signals from three different digital output (DO) cards. The digital trip output card is equipped with normally closed digital output contacts. The output of these contacts, namely the normally closed contact trip signals (FSS DO1~FSS DO3), is output to the boiler hard MFT circuit.
[0029] In application, the control loop expands these three trip signals using a 3-out-of-2 logic circuit. This circuit employs three relays (MFT1~MFT3), achieving the 3-out-of-2 function by increasing the capacity and number of relay contacts. Specifically, it includes three parallel communication channels: the first channel connects the normally open contacts of trip signal relays MFT1 and MFT2 in series; the second channel connects the normally open contacts of trip signal relays MFT2 and MFT3 in series; and the third channel connects the normally open contacts of trip signal relays MFT1 and MFT3 in series. This enables the 3-out-of-2 judgment and triggering of the trip relays (MTT1~MTT50). Once the boiler furnace protection system (FSS) loses power, the normally closed contacts of the three relays (FSS DO1~FSS DO3) of the FSS system switch output (DO) close and trigger the trip relays (MTT1~MTT50) of the boiler hard MFT circuit. Therefore, it can also serve as the power fault signal function of the boiler furnace protection system (FSS), eliminating the need to connect the power fault trip input signal of the boiler furnace protection system (FSS). This simplifies the control circuit, improves the reliability of the trip input signal of the boiler hard MFT circuit, and ensures that the boiler can be reliably stopped and protected when important control system components lose power.
[0030] In application, the manual MFT button on the control panel is configured as a dual-button system, triggering the boiler hard MFT circuit only when both buttons are activated simultaneously. The normally open contacts of the two buttons are connected in parallel and then in series to the boiler hard MFT trip input interface. This ensures that the boiler hard MFT circuit trip relays (MTT1~MTT50) can be reliably triggered when any contact of any button is activated.
[0031] In application, after an MFT occurs, the normally open contacts of trip relays MTT1 and MTT2 close to make the MFT trip protection self-holding. When the FSS system determines that all protection trip signals have disappeared, it outputs the FSS DO reset signal (normally closed contact opens), thereby resetting the MFT trip relays, and the unit can enter the restart procedure.
[0032] In the application, the control loop is also equipped with a power monitoring relay (DYJ). When the power supply of the loop fails, the normally closed contact of the power monitoring relay (DYJ) closes and sends a signal to the DCS control system for alarm.
[0033] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.
Claims
1. A boiler trip relay control circuit, characterized in that, This includes the boiler furnace protection system, the multiple-out-of-two logic control circuit, and the trip relay; The boiler furnace protection system includes multiple independent switch trip output cards. Each switch trip output card is equipped with a first normally closed switch trip output contact. The trip signal output terminal of the boiler furnace protection system is connected to each of the first normally closed switch trip output contacts. The multiple-choice logic control circuit includes trip signal relays that correspond one-to-one with the first normally closed switch trip output contacts. The coil of the trip signal relay is connected in series between the first normally closed switch trip output contact and the power supply line of the control circuit. The multiple-choice logic control circuit includes several parallel communication channels. Each communication channel is connected in series with the normally open contacts of any two trip signal relays. The multiple switch trip output cards of the boiler furnace protection system are connected to the boiler main fuel trip control circuit using normally closed relay contacts so as to trigger the trip relay of the boiler main fuel trip control circuit when the unit DCS power supply fails.
2. The boiler trip relay control circuit of claim 1, wherein, It also includes a button unit, which includes a first button and a second button. The two sets of normally open contacts of the first button are connected in parallel, and the two sets of normally open contacts of the second button are connected in parallel. The normally open contacts of the first button and the normally open contacts of the second button are connected in series to the coil terminal of the trip relay.
3. The boiler trip relay control circuit of claim 1, wherein, The boiler furnace protection system's switch trip output card is also equipped with a normally open switch output contact. The reset signal output terminal of the boiler furnace protection system is connected to the normally open switch output contact, and the normally open switch output contact is connected to the two parallel relay contacts of the trip relay.
4. The boiler trip relay control circuit of claim 1, wherein, It also includes a power monitoring relay, whose normally closed contact is connected to the alarm signal input terminal of the DCS control system.
5. The boiler trip relay control circuit of claim 1, wherein, The multiple-out-of-two logic control circuit is a three-out-of-two logic circuit, which includes three trip signal relays. The three-out-of-two logic circuit includes three parallel communication channels, and each communication channel is connected in series with the normally open contacts of any two trip signal relays.
6. The boiler trip relay control circuit of claim 1, wherein, The trip relay includes multiple trip relay coils connected in parallel.