Alarm system and method of distributed control system

Abstract

The invention discloses an alarm system and method for a decentralized control system, and belongs to the technical field of industrial automation control, and the system comprises an alarm collection and release subsystem which is disposed at a network node and is used for collecting local alarm data; the real-time alarm subsystem is used for acquiring the real-time alarm information acquired by the at least one alarm acquisition and release subsystem, and screening, sorting and displaying the acquired alarm information according to a retrieval condition; wherein the real-time alarm subsystem comprises a real-time alarm display end which is used for sending an alarm display subscription according to a display requirement; the real-time alarm synthesizer is used for receiving a subscription request of the real-time alarm display end and forwarding the subscription request to all online network nodes; according to the alarm system and method of the distributed control system, alarms are generated and processed on the end side in a centralized mode, the consistency of the alarm states of all HMI host nodes is guaranteed, and the data communication amount between HMI hosts and process control stations is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of industrial automation control, and particularly relates to an alarm system and method of a distributed control system. BACKGROUND

[0002] The DCS (Distributed Control System) alarm system, as a key core for ensuring production safety and stable operation in the field of industrial automation, plays a vital role in industrial production. It monitors the process parameters and equipment states in real time through the construction of a complete monitoring and response system. When an abnormality occurs in the production process, it notifies the operator to take measures and handle it in a timely manner through text prompts, sound and light reminders, message pushing and other ways, thereby effectively avoiding accidents and their expansion.

[0003] Under normal circumstances, the DCS collects the process parameters and the running states of the equipment in real time through sensors such as temperature, pressure, liquid level and flow sensors deployed in the field. The system judges the real-time collected process parameters and equipment state signals according to the preset alarm rules such as threshold, change rate and logical relationship, and triggers an alarm signal when the parameters meet the preset alarm conditions.

[0004] The alarm signal displays the alarm information in a prominent way through the human-machine interface of the operation station, usually including alarm position number, description, time, priority and other information, and reminds the operator through auxiliary alarm information and voice broadcast. The operator responds to and handles the alarm information generated by the system and confirms the alarm, indicating that the alarm information has been learned and the handling has begun. The generation, confirmation and recovery process of the alarm are recorded completely, which facilitates subsequent traceability and provides an important basis for accident analysis and system optimization.

[0005] In the prior art, the problems of the DCS alarm system mainly include the following aspects: Firstly, the existing DCS alarm system is mostly realized by relying on the real-time database of the monitoring system, and alarm rules are configured for the measuring points. Each HMI host independently judges, triggers and displays the alarm according to the real-time data of the measuring points in the real-time database. Each HMI host needs to update the complete real-time database in real time to make complete alarm judgment and triggering, which leads to a large amount of communication between the process control station and the system and high system load.

[0006] II. Operator's alarm confirmation operation needs to synchronize each operation station, update the state of the alarm. A separate configuration synchronization and alarm confirmation synchronization mechanism needs to be designed. When the alarm configuration synchronization is abnormal or the alarm confirmation synchronization is abnormal, inconsistent situations of each operation station alarm state display and prompt will occur, which will cause the operator's misjudgment, thereby affecting the safe and stable operation of the control site.

[0007] III. Alarm screening, filtering and sorting work needs to be processed independently on the HMI host that displays the alarm. Each HMI host node performs repeated work, which cannot effectively utilize the distributed parallel processing capability of the distributed system, and wastes the limited computing resources of the system.

[0008] IV. In order to ensure the uniformity of alarm configuration and triggering, a special independent alarm service system is set up. This system is responsible for collecting field data, executing alarm judgment, and providing alarm display access interface for operation station. Although it solves the problem of asynchronous alarm configuration and state of operation station to a certain extent and the problem of heavy communication load, it introduces new risks. Since the independent alarm service system becomes the hub component of the entire alarm system, its stability and reliability are crucial. In order to ensure its normal operation, a complex redundancy mechanism needs to be configured, which greatly increases the complexity of the system, increases the construction and maintenance cost, and also increases the probability of system failure.

[0009] V. The alarm generation mechanisms of process control station and HMI host are relatively independent, each having a set of independent alarm generation, collection, display, confirmation and retrieval mechanisms. The separated design not only increases the difficulty of design and implementation, but also is not conducive to the overall optimization and maintenance of the system. Therefore, based on the above defects, a new alarm system of distributed control system is needed to solve the existing problems. SUMMARY

[0010] The purpose of the present application is to provide an alarm system and method of distributed control system, to solve the problem of large amount of data communication between HMI host and process control station.

[0011] To achieve the above purpose, the present application provides the following technical scheme: an alarm system of distributed control system, comprising an alarm collection and release subsystem, a real-time alarm subsystem, a historical alarm server system and a historical alarm query client.

[0012] The alarm collection and release subsystem is responsible for collecting alarms, providing alarm data for real-time alarm display of the real-time alarm subsystem and alarm collection and warehousing of the historical alarm server system.

[0013] The alarm collection and publishing subsystem is composed of an alarm source and an alarm publishing service; it can be deployed in a process control station or an HMI host; the HMI host is also called an upper computer, and the process control station is also called a distributed processing unit or DPU; both the process control station and the HMI host are network nodes in a distributed control system; when deployed in the process control station, the process alarms of the controlled object and the system alarms of the process control station are collected and publishing services are provided; when deployed in the HMI host, the system alarms of the HMI host are collected and publishing services are provided. The alarm source is the source of alarm generation; if an alarm needs to be generated, a logical alarm source is required; the alarm generated by the alarm source includes alarm ID, alarm time, alarm content, and other alarm attributes; The alarm publishing service is used to collect alarms of the alarm source, organize them in different forms, and provide publishing functions for real-time alarm and historical alarm subscriptions.

[0014] Preferably, the alarm source is the source of alarm generation or alarm state change; the alarm state of the alarm source includes four states: normal (Normal), alarm unconfirmed (Alm), alarm confirmed (AlmAck), and alarm recovery (AlmClr); when deployed in the process control station, according to the configuration of the alarm point, the field process alarm or the system alarm of the process control station itself state abnormality is generated, updated, or recovered; when deployed in the HMI host, the system alarm of the HMI host itself state abnormality is generated, updated, or recovered.

[0015] Preferably, the alarm publishing service collects alarms generated by multiple alarm sources configured in the local machine, and provides alarm publishing services for real-time alarm and historical alarm subsystems.

[0016] Preferably, the alarm publishing service is composed of an alarm collector, a historical alarm record queue, a real-time alarm list, and an alarm publishing agent.

[0017] Preferably, the real-time alarm list adopts a linked list structure, and the historical alarm record adopts a circular queue structure.

[0018] Preferably, the historical alarm service system is deployed in a historical station host and is composed of a historical alarm collector, a historical alarm storage, and a historical alarm service. The historical alarm collector subscribes to alarm records of the alarm collection and publishing subsystem, and the alarm publishing agent of the alarm collection and publishing subsystem returns the number N of all historical alarm records in the historical alarm record queue and the head position P of the latest historical alarm record to it; the historical alarm collector reads the existing N alarm records in the historical alarm record queue and saves them to the historical alarm storage.

[0019] When there is a new alarm record in the historical alarm record queue of the alarm collection and publishing subsystem, it returns the position Q of the latest alarm record to the historical alarm collector; The historical alarm collector reads the alarm records in the historical alarm record queue (P+1)C, (P+2)C,..., Q position of the alarm collection and publishing subsystem in sequence, saves the alarm records into the historical alarm storage, and updates the position of the latest alarm record as Q. P represents the position of the alarm record returned by the historical alarm collector last time, and C represents the capacity of the historical alarm record queue. When new alarm records are continuously generated, the above steps are repeated.

[0020] Preferably, the historical alarm query client is deployed on the HMI host, and queries the historical alarm from the historical alarm server system according to the start and end time, alarm point ID, alarm type and sorting priority order.

[0021] Preferably, the historical alarm service of the historical alarm server system searches and sorts in the historical alarm storage according to the query requirements, and returns the result to the historical alarm query client for display.

[0022] Preferably, the real-time display subsystem queries the HMI host, process control station and other nodes on which the alarm collection and publishing subsystem is deployed and runs in sequence according to the alarm display conditions, and performs summary display.

[0023] Preferably, the real-time alarm subsystem is deployed on the HMI host for alarm display, and is composed of a real-time alarm display end and a real-time alarm synthesizer.

[0024] The application further provides an alarm state updating method of an alarm source in an alarm system of a distributed control system, which comprises the following steps: 1. When a new alarm is generated by the alarm source, a new alarm entry is added to the real-time alarm list, including alarm point ID (ID), time stamp (TimeStamp), alarm level (AlmLevel) and alarm state (AlmState), and the alarm state is set as an alarm unconfirmed state (Alm); a new record is added to the historical alarm record queue, including alarm point ID (ID), time stamp (TimeStamp), alarm level (AlmLevel) and record type (Type), and the record type is set as a new alarm (NewAlm); 2. When the alarm generated by the alarm source is confirmed, the corresponding alarm entry is searched in the real-time alarm list according to the alarm point ID (ID); 2.1 If the alarm state of the alarm entry is the alarm unconfirmed state (Alm), the time stamp (TimeStamp) of the alarm entry is updated in the real-time alarm list, and the alarm state of the alarm entry is set as the alarm confirmed state (AlmAck); 2.2 If the alarm status of the alarm entry is AlmClr, delete the alarm entry from the real-time alarm list.

[0025] In the historical alarm record queue, add 1 to the head position P to obtain a new head position P1, P1=(P+1)%C, % represents a modulo calculation, and at P1, a new record is added, including an alarm point identifier (ID), a timestamp (TimeStamp), an alarm level (AlmLevel), and a record type (Type), and the record type is set to AckAlm. 3. When the alarm generated by the alarm source is recovered, the corresponding alarm entry is searched in the real-time alarm list according to the alarm point identifier (ID); 3.1 If the alarm status of the alarm entry is Alm, update the timestamp (TimeStamp) of the alarm entry in the real-time alarm list, and set the alarm status of the alarm entry to AlmClr. 3.2 If the alarm status of the alarm entry is AlmAck, delete the alarm entry from the real-time alarm list. In the historical alarm record queue, add 1 to the head position P to obtain a new head position P1, P1=(P+1)%C, % represents a modulo calculation, and at P1, a new record is added, including an alarm point identifier (ID), a timestamp (TimeStamp), an alarm level (AlmLevel), and a record type (Type), and the record type is set to AlmClr.

[0026] The application further provides a real-time alarm method of an alarm system of a distributed control system, comprising: The real-time alarm display end sends an alarm display subscription to the real-time alarm synthesizer according to display requirements, and requests to include the number of display N, the cutoff time t, the alarm level l, the alarm status s, and the sorting field priority o; the real-time alarm synthesizer forwards the subscription request to all online HMI hosts and process control stations; After the alarm publishing agent in the alarm acquisition and publishing subsystem deployed in the HMI host and the process control station receives the subscription request, the alarm publishing agent searches for alarm entries meeting the conditions in the real-time alarm list periodically according to the cutoff time, the alarm level, and the alarm status, sorts the alarm entries according to the sorting field priority o, intercepts the first N alarm entries, and respectively pushes the first N alarm entries to the HMI host for subscription alarm display to form a real-time alarm entry set AlmSet; The real-time alarm synthesizer of the real-time alarm display subsystem deployed in the HMI host periodically receives a total of M sets of real-time alarm entries AlmSet1, AlmSet2, … AlmSetM pushed by the alarm acquisition and publishing subsystems in the online HMI hosts and process control stations, merges them to form AlmSet, and then sorts them according to the sorting field priority o, and pushes the first N alarm records to the real-time alarm display end for display.

[0027] The technical effects and advantages of the present application: the alarm system and method of the distributed control system, the HMI host and the process control station adopt a unified alarm acquisition and publishing mechanism, the alarms are generated and processed on the end side, ensuring the consistency of the alarm states of each HMI host node, greatly reducing the data communication amount between the HMI host and the process control station; the distributed alarm processing architecture without independent alarm service improves the stability of the system; the distributed alarm processing improves the real-time performance and concurrent processing capability of the alarm, and improves the efficiency of the system. The integrated and universal alarm acquisition and processing system method can be deployed in the process control station and the HMI host, and has good universality.

[0028] The universal alarm acquisition and publishing subsystem deployed in the HMI host and the process control station acquires process alarms and system alarms, and stores them in different storage areas according to the differences in access and use characteristics of real-time alarms and historical alarm records, and provides data publishing services for the display of real-time alarms and the storage of historical alarms. The hierarchical real-time alarm filtering and screening mechanism fully utilizes the hierarchical and distributed processing capability of the distributed system. Based on the realization of the alarm system function, the system architecture is simplified, the computing and communication overhead and the requirement for system hardware resources are reduced, and the real-time performance, stability and concurrent processing capability of the system are improved. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The figure is a structural schematic diagram of the system of the present application; Figure 2 The figure is a structural schematic diagram of the alarm publishing service of the present application; Figure 3 The figure is a structural schematic diagram of the real-time alarm subsystem of the present application. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0031] This invention provides, for example Figure 1 The alarm system of the distributed control system shown consists of an alarm acquisition and distribution subsystem, a real-time alarm subsystem, a historical alarm server system, and a historical alarm query client.

[0032] The alarm collection and publishing subsystem is responsible for collecting alarms and providing alarm data for the real-time alarm display of the real-time alarm subsystem and the alarm collection and storage of the historical alarm server system.

[0033] The real-time display subsystem queries the HMI host, process control station, and other nodes of the deployed and running alarm collection and release subsystem in sequence according to the alarm display conditions, and then summarizes and displays the results.

[0034] The historical alarm server system collects alarms from the alarm collection and publishing subsystem and stores them in the database.

[0035] The historical alarm query client queries the historical alarm server system based on the historical alarm search criteria and displays the query results.

[0036] The alarm acquisition and publishing subsystem consists of alarm sources and alarm publishing services. It can be deployed at either the process control station or the HMI host. When deployed at the process control station, it acquires process alarms from the controlled objects and system alarms from the process control station, and provides publishing services. When deployed at the HMI host, it acquires system alarms from the HMI host and provides publishing services.

[0037] An alarm source is the origin of an alarm or the change in alarm status. Alarm status includes four states: Normal, Unacknowledged (Alm), Acknowledged (AlmAck), and Recovered (AlmClr). When deployed at a process control station, it generates, updates, or recovers field process alarms or system alarms indicating abnormal status of the process control station itself, based on the alarm point configuration. When deployed at an HMI host, it generates, updates, or recovers system alarms indicating abnormal status of the HMI host itself. The alarm publishing service collects alarms generated by multiple alarm sources configured on the local machine and provides alarm publishing services for the real-time alarm subsystem and the historical alarm subsystem.

[0038] The alarm publishing service consists of an alarm collector, a historical alarm record queue, a real-time alarm list, and an alarm publishing agent; such as Figure 2 As shown; The alarm collector gathers the alarm status of the alarm sources: 1. When a new alarm is generated by an alarm source, a new alarm entry is added to the real-time alarm list, including alarm point identification (ID), time stamp (TimeStamp), alarm level (AlmLevel) and alarm state (AlmState), and the alarm state is set to the alarm unconfirmed state (Alm); in the historical alarm record queue, a new record is added, including alarm point identification (ID), time stamp (TimeStamp), alarm level (AlmLevel) and record type (Type), and the record type is set to new alarm (NewAlm).

[0039] 2. When the alarm generated by the alarm source is confirmed, the corresponding alarm entry is searched in the real-time alarm list according to the alarm point identification (ID).

[0040] 2.1 If the alarm state of the alarm entry is the alarm unconfirmed state (Alm), the time stamp (TimeStamp) of the alarm entry is updated in the real-time alarm list, and the alarm state of the alarm entry is set to the alarm confirmed state (AlmAck); 2.2 If the alarm state of the alarm entry is the alarm recovery state (AlmClr), the alarm is deleted in the real-time alarm list.

[0041] In the historical alarm record queue, the head position P is added by 1 to obtain a new head position P1, P1= (P+1)%C, % represents the modulus calculation, and a new record is added at P1, including alarm point identification (ID), time stamp (TimeStamp), alarm level (AlmLevel) and record type (Type), and the record type is set to confirmed alarm (AckAlm); 3. When the alarm generated by the alarm source is recovered, the corresponding alarm entry is searched in the real-time alarm list according to the alarm point identification (ID).

[0042] 3.1 If the alarm state of the alarm entry is the alarm unconfirmed state (Alm), the time stamp (TimeStamp) of the alarm entry is updated in the real-time alarm list, and the alarm state of the alarm entry is set to the alarm recovery state (AlmClr); 3.2 If the alarm state of the alarm entry is the alarm confirmed state (AlmAck), the alarm is deleted in the real-time alarm list.

[0043] In the historical alarm record queue, the head position P is added 1 to obtain a new head position P1, P1= (P+1) %C, % represents the modulus calculation, and a new record is added at P1, including alarm point identification (ID), time stamp (TimeStamp), alarm level (AlmLevel) and record type (Type), and the record type is set to alarm recovery (AlmClr).

[0044] The real-time alarm subsystem is deployed on the HMI host for alarm display, and is composed of a real-time alarm display end and a real-time alarm synthesizer. Figure 3 As shown in the figure. The real-time alarm display end sends an alarm display subscription to the real-time alarm synthesizer according to display requirements, and requests to contain the number of display N, the cutoff time t, the alarm level l, the alarm state s and the sorting field priority o; the real-time alarm synthesizer forwards the subscription request to all online HMI hosts and process control stations, a total of M nodes. The technical meaning of subscription is to initiate a data request, such as when displaying an alarm, a request for subscribing to alarm display content needs to be initiated; The alarm publishing agent in the alarm acquisition and publishing subsystem deployed in the HMI host and the process control station receives the subscription request, and according to the cutoff time, the alarm level and the alarm state, periodically searches the real-time alarm list to retrieve alarm entries that meet the conditions, and sorts them according to the sorting field priority o, and intercepts the first N entries to form a real-time alarm entry set AlmSet and push it to the HMI host for subscription alarm display.

[0045] The real-time alarm synthesizer of the real-time alarm display subsystem deployed in the HMI host periodically receives the pushed real-time alarm entry sets AlmSet1, AlmSet2, … AlmSetM from the alarm acquisition and publishing subsystems of the total M online HMI hosts and process control stations, and merges them to form AlmSet. Then, according to the sorting field priority o, the first N alarm records are intercepted and pushed to the real-time alarm display end for display. The alarm display end is the computer host for displaying alarms.

[0046] The historical alarm server system is deployed on the historical station host, and is composed of a historical alarm collector, a historical alarm storage and a historical alarm service. The historical alarm collector subscribes to the alarm records of the alarm acquisition and publishing subsystem, and the alarm publishing agent of the alarm acquisition and publishing subsystem returns the number N of all alarm records in the historical alarm record queue (AlmRecCycList) and the position P of the latest alarm record. The historical alarm collector reads the existing N alarm records in the historical alarm record queue and saves them to the historical alarm storage.

[0047] When there is a new alarm record in the alarm collection and publishing subsystem historical alarm record queue, it returns the position Q of the latest alarm record to the historical alarm collector; the historical alarm collector reads the alarm records in the historical alarm record queue (P+1)%C, (P+2)%C, …, Q of the alarm collection and publishing subsystem, saves the alarm records to the historical alarm storage, and updates the position of the latest alarm record as Q. P represents the position of the alarm record returned by the historical alarm collector last time, and C represents the capacity of the historical alarm record queue. When there is a new alarm record, the process is repeated.

[0048] The historical alarm query client is deployed on the HMI host, and queries the historical alarm from the historical alarm server system according to the start and end time, alarm point ID, alarm type and sorting priority order.

[0049] The historical alarm service of the historical alarm server system searches and sorts in the historical alarm storage according to the query requirement, and returns the result to the historical alarm query client for display.

[0050] Although the preferred embodiments of the present application have been described, those skilled in the art who are familiar with the basic inventive concept can make additional changes and modifications to the embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0051] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

[0052] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and not for the purpose of limiting the present application, although the present application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, it still can modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application, should be included in the protection scope of the present application.

Claims

1. An alarm system for a distributed control system, characterized in that: include: The alarm data collection and publishing subsystem is deployed on network nodes to collect local alarm data. A real-time alarm subsystem is used to acquire real-time alarm information collected by at least one of the alarm acquisition and publishing subsystems, and to filter, sort and display the acquired alarm information according to search conditions. The real-time alarm subsystem includes: The real-time alarm display terminal is used to send alarm display subscriptions according to display requirements; A real-time alarm synthesizer is used to receive subscription requests from the real-time alarm display terminal and forward the subscription requests to all online network nodes.

2. The alarm system of a distributed control system according to claim 1, characterized in that: The alarm collection and dissemination subsystem includes: Alarm source used to generate alarm data; And alarms used to collect the alarm sources, using different data structures for storage based on different collection mechanisms for real-time alarms and historical alarms, and providing an alarm publishing service that provides publishing functionality for subscriptions to real-time alarms and historical alarms; The alarm data includes: alarm point identifier, timestamp, alarm level, and alarm status.

3. The alarm system of a distributed control system according to claim 2, characterized in that: The alarm publishing service includes: Alarm collector, historical alarm record queue, real-time alarm list, and alarm publishing agent; The alarm collector is used to collect the alarm status of the alarm source in real time. The real-time alarm list adopts a linked list structure; The historical alarm records are constructed using a circular queue structure. The alarm publishing agent is used to handle alarm subscriptions and alarm publishing.

4. The alarm system of a distributed control system according to claim 1, characterized in that: The system also includes: The historical alarm server system is used to collect alarm data from at least the alarm collection and publishing subsystem and store it in the database; The historical alarm query client is used to query the historical alarm server system based on historical alarm search criteria and display the query results.

5. The alarm system of a distributed control system according to claim 4, characterized in that: The historical alarm server system includes: a historical alarm collector, historical alarm storage, and historical alarm service; The historical alarm collector is used to subscribe to alarm records from the alarm publishing service of the alarm collection and publishing subsystem. The alarm publishing service returns to the historical alarm collector the total number N of all historical alarm records in the historical alarm record queue and the head position P of the latest historical alarm record in the queue; and saves the existing N alarm records in the historical alarm record queue to the historical alarm storage. The historical alarm service is used to retrieve and sort historical alarms in the storage according to query requirements, and return the results to the historical alarm query client for display.

6. The alarm system of a distributed control system according to claim 5, characterized in that: When a new alarm record is added to the historical alarm record queue, the location Q of the latest alarm record is returned to the historical alarm collector through the alarm publishing service. The historical alarm collector sequentially reads the alarm records at positions (P+1)%C, (P+2)%C, ..., Q from the historical alarm record queue of the alarm collection and release subsystem, saves the alarm records to the historical alarm storage, and updates the position of the latest alarm record to Q. P represents the position of the alarm record last returned by the historical alarm collector, and C represents the capacity of the historical alarm record queue.

7. A method for updating the alarm status of an alarm source in an alarm system of a distributed control system according to any one of claims 2-6, characterized in that: include: When a new alarm is generated by an alarm source, a new alarm entry is added to the real-time alarm list, including the alarm point identifier, timestamp, alarm level, and alarm status, and the alarm status is set to alarm unacknowledged status; a new record is added to the historical alarm record queue, including the alarm point identifier, timestamp, alarm level, and record type, and the record type is set to new alarm. Once an alarm generated by an alarm source is confirmed, the corresponding alarm entry is retrieved from the real-time alarm list based on the alarm point identifier. Once the alarm from the alarm source is restored, the corresponding alarm entry is retrieved from the real-time alarm list based on the alarm point identifier.

8. The method according to claim 7, characterized in that: Once an alarm generated by an alarm source is confirmed, the process of retrieving the corresponding alarm entry from the real-time alarm list based on the alarm point identifier includes: If the alarm status of the alarm entry is "alarm unacknowledged", then update the timestamp of the alarm entry in the real-time alarm list and set the alarm status of the alarm entry to "alarm acknowledged". If the alarm status of the alarm entry is alarm recovery status, then delete the alarm from the real-time alarm list; In the historical alarm record queue, increment the queue head position P by 1 to get the new queue head position P1, P1 = (P+1)%C, where % represents modulo calculation. Add a new record at the new queue head position P1 and set the record type to confirmed alarm.

9. The method according to claim 7, characterized in that: When the alarm generated by the alarm source is restored, the process of retrieving the corresponding alarm entry in the real-time alarm list based on the alarm point identifier includes: If the alarm status of the alarm entry is "alarm unacknowledged", then update the timestamp of the alarm entry in the real-time alarm list and set the alarm status of the alarm entry to "alarm recovered". If the alarm status of the alarm entry is alarm confirmed, then delete the alarm from the real-time alarm list; In the historical alarm record queue, increment the queue head position P by 1 to get the new queue head position P1, P1 = (P+1)%C, where % represents modulo calculation. Add the new record at P1 and set the record type to alarm recovery.

10. A real-time alarm method for an alarm system based on any one of claims 1-6 of a distributed control system, characterized in that: include: The real-time alarm display terminal sends an alarm display subscription to the real-time alarm synthesizer according to the display requirements. The request includes the number of displays N, the deadline t, the alarm level l, the alarm status s, and the sorting field priority o. The real-time alarm synthesizer forwards the subscription request to all M online network nodes. After receiving the subscription request, the alarm publishing agent of the alarm collection and publishing subsystem periodically retrieves alarm entries that meet the conditions in the real-time alarm list according to the deadline, alarm level and alarm status, sorts them according to the priority field o, extracts the top N entries, and forms a real-time alarm entry set AlmSet, which is then pushed to the HMI host that subscribes to the alarm display. The real-time alarm synthesizer of the real-time alarm display subsystem periodically receives a total of M sets of real-time alarm entries AlmSet1, AlmSet2, ... AlmSetM pushed from the online alarm acquisition and release subsystems. These sets are merged to form AlmSet. The alarms are then sorted according to the priority field o, and the first N alarm records are selected and pushed to the real-time alarm display terminal for display.

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