A high time-precision distributed control system and control method

Abstract

The application relates to a distributed control system, in particular to a high-time-precision distributed control system and a control method, which solves the technical problem of low time precision of synchronous control of an existing large-scale long-distance distributed control system. The distributed control system comprises an upper computer system and K front-end customized control devices, the upper computer system comprises an operator console, a time server and a database server; the front-end customized control device comprises a power module, a CPU module and T I / O modules connected with the power module, the front-end industrial personal computer and the execution mechanism function are uniformly integrated into the front-end customized control device, the system structure is more simple and reliable; the time precision of instruction output synchronization is the time synchronization precision of the I / O module, is not affected by the system scale and / or node distance, and the time precision of the system is high; the front-end customized control device adopts a tight coupling structure and has stronger flexibility, expandability and reliability.

Description

Technical Field

[0001] This invention relates to distributed control systems, and more specifically to a high-time-accuracy distributed control system and its control method. Background Technology

[0002] For large-scale distributed control systems involving fields related to national economy and people's livelihood such as hydropower, wind power, petrochemicals, municipal administration, and national defense, the control nodes are often widely distributed, and the front-end control equipment of each control node is required to execute actions according to unified and precise control instructions. The system has high requirements for the time synchronization accuracy of instruction input and output between various control nodes.

[0003] Existing distributed control systems generally consist of a host computer, a front-end industrial control computer, and actuators. The front-end industrial control computer is responsible for outputting specific control logic commands and communicating with the host computer, while the actuators are responsible for executing the commands. The time synchronization accuracy of the command output depends on factors such as the communication overhead of the front-end industrial control computer, the system time accuracy, and the uncertainty of task switching time. When the control system is large-scale or the control nodes are far apart, the time synchronization accuracy of the command output is typically on the order of 10ms. However, the synchronization control time accuracy of existing distributed control systems is relatively low, making it difficult to meet this requirement. Therefore, solving the problem of high-time-accuracy synchronization control in large-scale, long-distance distributed control systems has significant practical implications. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problem of low synchronization control time accuracy in existing large-scale, long-distance distributed control systems, and to provide a high-time-accuracy distributed control system and control method.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A high-time-accuracy distributed control system, characterized in that it includes a host computer system and a customized control front-end system connected via a network.

[0007] The host computer system includes L independent operator consoles, M time servers, and N database servers, where L, M, and N are all positive integers.

[0008] The operator console is used to set the instruction timetable according to control requirements; the time server is used for precise time synchronization and to achieve high-precision time synchronization between the host computer system and the control front-end customized system; and the database server is used for process data storage and archiving.

[0009] Each of the aforementioned control front-end customization systems includes K independent front-end customization control devices, where K is a positive integer;

[0010] The front-end customized control device includes a power module, a CPU module and T I / O modules respectively connected to the power module, where T is a positive integer;

[0011] Each CPU module is connected to L operator consoles, M time servers, and N database servers via a network, and to T I / O modules via a backplane interface, for communication between the host computer system and the customized control front-end system.

[0012] The CPU module is used to communicate with the host computer system and drive the control I / O module; the I / O module is used to obtain high-precision absolute time and output control commands in real time according to the instruction timetable.

[0013] Furthermore, the power module is tightly coupled to the CPU module and the T I / O modules, and the CPU module is connected to the T I / O modules via a backplane interface.

[0014] Furthermore, the time server supports the PTP protocol.

[0015] Furthermore, the host computer system and the customized control front-end system are connected via Ethernet.

[0016] A control method for a high-time-accuracy distributed control system, based on the aforementioned high-time-accuracy distributed control system, is characterized by comprising the following steps:

[0017] Step 1: Initialize the underlying control system, which includes an operator console, a CPU module, and an I / O module;

[0018] Step 2: Each operator console in the host computer system sets an instruction schedule according to control requirements and sends it to each CPU module;

[0019] Step 3: Each CPU module receives the instruction timetable transmitted from the operator console and communicates with its corresponding T I / O modules to write the instruction timetable into the corresponding registers in the T I / O modules.

[0020] Step 4: Each CPU module reads the real-time status of each data register or I / O terminal in its corresponding T I / O modules, updates the values ​​corresponding to the real-time status of each data register or I / O terminal in the real-time database, and then stores them in the database server.

[0021] Step 5: Each I / O module obtains a high-precision absolute time T from the time server and latches it into the system time register of the I / O module;

[0022] Step 6: The I / O module compares the high-precision absolute time T in the system time register with the instruction timetable. If the high-precision absolute time is within the time range of the instruction timetable, the corresponding output terminal of the I / O module outputs the instruction in real time at the predetermined time of the instruction timetable, and then executes Step 7; otherwise, no instruction is output, and Step 7 is executed directly.

[0023] Step 7: Repeat steps 4-6 until high-time-precision distributed control is completed.

[0024] Further, step 1 specifically includes:

[0025] 1.1 Initialize the operator console

[0026] Each of the L operator consoles loads the human-machine interface and performs a self-test on the communication link between itself and the K CPU modules.

[0027] 1.2 Initialize the CPU module

[0028] 1.2.1 Construct a distributed real-time database runtime environment to enable real-time access, modification, monitoring, and storage of process data;

[0029] 1.2.2 Load the interface driver module and establish a communication channel between the real-time database in the CPU module and its corresponding T I / O modules;

[0030] 1.2.3 Load the distributed real-time database, define semaphores, establish the database, and load data according to actual process control requirements;

[0031] 1.3 Initialize the I / O module

[0032] The I / O module initializes the state of its I / O terminals.

[0033] Furthermore, in step 3, the instruction timetable includes the sequence of actions to be executed by the front-end customization system at future times and the execution time of the corresponding actions;

[0034] Each action and its corresponding execution time are uniquely mapped to the real-time database within the CPU module via a unique variable name.

[0035] Furthermore, in steps 5 and 6, the I / O module implements timing and instruction input and output in hardware.

[0036] Further, step 4 specifically involves: setting the update cycle ΔT for the real-time database within each CPU module; then, each CPU module reads the real-time status of each data register or I / O terminal within its corresponding T I / O modules according to the update cycle, updates the values ​​corresponding to the real-time status of each data register or I / O terminal in the real-time database, and then stores them in the database server.

[0037] Compared with the prior art, the present invention has the following beneficial technical effects:

[0038] 1. The present invention provides a high time accuracy distributed control system, which consists of a host computer system and a front-end customized control system. The synchronization time accuracy of the instruction output is the time synchronization accuracy of the I / O module. It is not affected by the scale of the control system and / or the distance between control nodes, nor is it related to the communication overhead between the host computer system and the front-end customized control system, the communication cycle between the CPU module and each I / O module, or the update cycle of the real-time database in the CPU module. The system has high time accuracy.

[0039] 2. The high time accuracy distributed control system provided by this invention integrates the functions of the front-end industrial control computer and the actuator into the front-end customized control equipment, making the system structure simpler and more reliable, while not affecting the normal operation of other modules in the system;

[0040] 3. The high time accuracy distributed control system provided by this invention has no restrictions or constraints on the communication protocol and communication interface type between the CPU module and I / O module in the front-end customized system. It is compatible with various types of control units, has strong portability, and is suitable for various types of distributed control systems.

[0041] 4. The high time accuracy distributed control system provided by this invention adopts a tightly coupled design mode for the front-end customized control equipment, which has greater flexibility, scalability and reliability compared with the design concept of front-end industrial control computer + actuator.

[0042] 5. The present invention provides a control method for a high-time-accuracy distributed control system. The underlying control logic and time synchronization task are directly implemented by the I / O module located at the lowest level of the control system through hardware, which can effectively improve the instruction output accuracy between multiple control nodes. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the high-time-accuracy distributed control system provided in an embodiment of the present invention.

[0044] Figure 2 A flowchart of a high-time-precision distributed control method provided in an embodiment of the present invention;

[0045] The annotations in the attached figures are explained as follows:

[0046] 1-Host computer system, 2-Operator console, 3-Time server, 4-Database server, 5-Control front-end customized system, 6-Power supply module, 7-CPU module, 8-I / O module. Detailed Implementation

[0047] The high-time-accuracy distributed control system and control method proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of this invention and are not intended to limit the scope of protection of this invention.

[0048] A high-time-accuracy distributed control system, such as Figure 1 As shown, the system includes a host computer system 1 and a control front-end customization system 5 connected via Ethernet. The host computer system 1 can be further subdivided functionally into: operator consoles 2, time servers 3, and database servers 4. The host computer system 1 includes L independent operator consoles 2 (OPI sites), M time servers 3, and N database servers 4, where L, M, and N are positive integers. Operator consoles 2 are used to set instruction timetables according to control requirements and are responsible for tasks such as process control, equipment status monitoring, and application development. Time servers 3 are used for precise time synchronization and high-precision time synchronization between the host computer system 1 and the control front-end customization system 5. Database servers 4 are used for process data storage and archiving. When multiple time servers 3 are present, they are connected to the same root server, and the multiple time servers 3 obtain time from the root server to synchronize time with the control front-end customization system 5.

[0049] The control front-end customized system 5 includes K independent front-end customized control devices, where K is a positive integer. Each front-end customized control device includes a power module 6, a CPU module 7, and T I / O modules 8, all connected to the power module 6, where T is a positive integer. The power module 6, CPU module 7, and T I / O modules 8 are tightly coupled and connected via a backplane interface, giving the distributed control system greater flexibility, scalability, and reliability.

[0050] Each CPU module 7 is connected to L operator consoles 2, M time servers 3, and N database servers 4 via a network, and to T I / O modules 8 via interfaces. This enables communication between the host computer system 1 and the control front-end customized system 5, the construction and operation of the distributed database, and the drive control of the I / O modules. Data sharing between any operator console 2 and the control front-end customized system 5, as well as between each front-end customized control device, can be achieved through the distributed database residing in each CPU module 7. During the operation of each front-end customized control device, the CPU module 7 only needs to cache the real-time operating data of the current device; the system's historical data is stored in the database server 4 of the host computer system. Therefore, this embodiment has no special requirements for the storage space of the CPU module 7.

[0051] The PTP (IEEE 1588) protocol is a network-based precision clock synchronization protocol that uses a combination of software and hardware for clock synchronization. Distributed nodes exchange network data packets with the master clock to achieve time and frequency synchronization among nodes, achieving sub-microsecond accuracy. Therefore, in this embodiment, the time server 3 supports the PTP protocol. The host computer system 1 and the customized control front-end system 5 are connected via Ethernet.

[0052] I / O module 8 is used to obtain high-precision absolute time and output control commands in real time according to the instruction timetable, that is, to realize the functions of low-level control logic, precise clock synchronization, and high-time-precision instruction input and output. I / O module 8 implements the time synchronization function and control logic input and output in hardware. Compared with the software method, the hardware implementation of the time synchronization function and control logic input and output ensures the time determinism of instruction input and output. The instruction output synchronization accuracy of each control node in the system is the time synchronization accuracy S of I / O module 8.

[0053] The distributed control system provided in this embodiment has no limit on the scale and number of systems or the distance between each front-end customized control device. Its instruction output synchronization accuracy is the time synchronization accuracy S of the I / O module 8, and is independent of the communication overhead between the host computer system 1 and the front-end customized control system 5, the communication cycle between the CPU module 7 and each I / O module 8, and the update cycle of the real-time database in the CPU module 7.

[0054] The distributed control system provided in this embodiment adopts a distributed real-time database structure. Any operator console 2 and the customized control front-end system 5, as well as each customized front-end control device, can share network data through the distributed database residing in each CPU module 7. The customized front-end control device adopts a tightly coupled design mode, which has greater flexibility, scalability and reliability compared with the design concept of front-end industrial control computer + actuator. The underlying control logic and time synchronization tasks are directly implemented by the hardware inside the I / O module 8 located at the bottom of the control system, which can effectively improve the synchronization time accuracy of instruction output between multiple control nodes.

[0055] This embodiment also provides a control method for a high-time-accuracy distributed control system, based on the aforementioned high-time-accuracy distributed control system, such as... Figure 2 As shown, it includes the following steps:

[0056] Step 1: Initialize the underlying control system, which includes an operator console 2, a CPU module 7, and an I / O module 8, specifically:

[0057] 1.1 Initialize Operator Console 2

[0058] Operator console 2 loads the human-machine interface and performs a self-test on the communication link between it and CPU module 7;

[0059] 1.2 Initialize CPU module 7

[0060] 1.2.1 Construct a distributed real-time database runtime environment to enable real-time access, modification, monitoring, and storage of process data;

[0061] 1.2.3 Load the interface driver module to establish a communication channel between the real-time database and I / O module 8;

[0062] 1.2.3 Load the distributed real-time database, define semaphores, establish the database, and load data according to actual process control requirements;

[0063] 1.3 Initialize the I / O module 8

[0064] I / O module 8 initializes the state of its I / O terminals.

[0065] Step 2: Each operator console 2 in the host computer system 1 sets an instruction timetable according to control requirements and distributes it to each CPU module 7. The instruction timetable includes the sequence of actions to be executed by the control front-end customization system 5 at future times, as well as the execution time of the corresponding actions. The execution time of each action is uniquely mapped to the real-time database running within the CPU module 7 through a unique variable name. When the instruction timetable content of the operator console 2 is changed or set, the corresponding data in the real-time database within the CPU module 7 also changes accordingly.

[0066] Step 3: Each CPU module 7 receives the instruction timetable transmitted by the operator console 2 via Ethernet and communicates with its corresponding T I / O modules 8, writing the instruction timetable into the corresponding registers within the I / O modules 8. The communication protocol between the CPU module 7 and each I / O module 8 is not limited.

[0067] Step 4: Set the update cycle of the real-time database for each CPU module 7 to ΔT. Each CPU module 7 reads the real-time status of each data register or I / O terminal in its corresponding T I / O modules 8 according to the update cycle, updates the value corresponding to the real-time status of each data register or I / O terminal in the real-time database, and then stores it in the database server 4.

[0068] Step 5: Each I / O module 8 obtains a high-precision absolute time T through the time server 3 and latches it into the system time register of the I / O module 8. The absolute time precision of the I / O module 8 is S.

[0069] Step 6: I / O module 8 compares the high-precision absolute time T in the system time register with the instruction timetable. If the high-precision absolute time is within the time range of the instruction timetable, the corresponding output terminal of I / O module 8 outputs the instruction in real time at the predetermined time of the instruction timetable, and then executes step 7; otherwise, no instruction is output, and step 7 is executed directly.

[0070] Step 7: Repeat steps 4-6 until high-time-precision distributed control is completed.

Claims

1. A high time-precision distributed control method, wherein the high time-precision distributed control system includes a host computer system (1) and a control front-end customized system (5) connected via a network. The host computer system (1) includes L independent operator consoles (2), M time servers (3), and N database servers (4), wherein, L, M, and N are all positive integers; The operator console (2) is used to set the instruction timetable according to control requirements. The time server (3) is used for precise time synchronization and to realize high-precision time synchronization between the host computer system (1) and the control front-end customized system (5). The database server (4) is used for process data storage and archiving. The control front-end customization system (5) includes K independent front-end customization control devices, where K is a positive integer; Each of the aforementioned front-end customized control devices includes a power module (6), a CPU module (7) and T I / O modules (8) respectively connected to the power module (6), where T is a positive integer; Each of the CPU modules (7) is connected to L operator consoles (2), M time servers (3), and N database servers (4) via network interfaces, and to T I / O modules (8) via backplane interfaces. The CPU module (7) is used to communicate with the host computer system (1) and drive the control I / O module (8); the I / O module (8) is used to obtain high-precision absolute time and output control commands in real time according to the instruction timetable; Its characteristic is that it includes the following steps: Step 1: Initialize the operator console (2), CPU module (7), and I / O module (8); Step 2: Each operator console (2) sets the instruction timetable according to the control requirements and sends it to each CPU module (7). Step 3: Each CPU module (7) receives the instruction timetable transmitted by L operator consoles (2) and communicates with its corresponding T I / O modules (8) to write the instruction timetable into the corresponding registers in the T I / O modules (8); Step 4: Each CPU module (7) reads the real-time status of each data register or I / O terminal in its corresponding T I / O modules (8), updates the value corresponding to the real-time status of each data register or I / O terminal in the real-time database, and then stores it in the database server (4). Step 5: The I / O module (8) obtains the high-precision absolute time T0 through the time server (3) and latches it into the system time register of the I / O module (8); Step 6: The I / O module (8) compares the high-precision absolute time T0 in the system time register with the instruction timetable. If the high-precision absolute time T0 is within the time range of the instruction timetable, the corresponding output terminal of the I / O module (8) outputs the instruction in real time at the predetermined time of the instruction timetable, and then executes step 7; otherwise, no instruction is output, and step 7 is executed directly. Step 7: Repeat steps 4-6 until high-time-precision distributed control is completed.

2. The high-time-precision distributed control method according to claim 1, characterized in that: The power module (6) is connected to the CPU module (7) and the T I / O modules (8) through a backplane interface via a tightly coupled structure.

3. The high-time-precision distributed control method according to claim 2, characterized in that: The time server (3) uses the PTP protocol.

4. The high-time-precision distributed control method according to claim 3, characterized in that: The host computer system (1) and the control front-end customization system (5) are connected via Ethernet.

5. A high-time-precision distributed control method according to any one of claims 1-4, characterized in that, Step 1 specifically involves: 1.1 Initialize the operator console (2) L operator consoles (2) load human-machine interfaces respectively, and perform self-tests on the communication links between them and K CPU modules (7); 1.2 Initialize the CPU module (7) 1.2.1 Construct a distributed real-time database runtime environment to enable real-time access, modification, monitoring, and storage of process data; 1.2.2 Load the interface driver module and establish a communication channel between the real-time database in the CPU module (7) and its corresponding T I / O modules (8); 1.2.3 Load the distributed real-time database, define semaphores, establish the database, and load data according to actual process control requirements; 1.3 Initialize the I / O module (8) The I / O module (8) initializes the state of its I / O terminals.

6. The high-time-precision distributed control method according to claim 5, characterized in that, In step 3, the instruction timetable includes the sequence of actions to be executed by the front-end customization system (5) at a future time and the execution time of the corresponding actions; Each action and its corresponding execution time are uniquely mapped to the real-time database within the CPU module (7) via a unique variable name.

7. The high-time-accuracy distributed control method according to claim 6, characterized in that, In steps 5 and 6, the I / O module (8) implements timing and instruction input and output in hardware.

8. The high-time-precision distributed control method according to claim 7, characterized in that, Step 4 is as follows: First, set the update cycle of the real-time database for each CPU module (7). Then, each CPU module (7) reads the real-time status of each data register or I / O terminal in its corresponding T I / O modules (8) according to the update cycle, updates the value corresponding to the real-time status of each data register or I / O terminal in the real-time database, and then stores it in the database server (4).

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