CN115134185A - A method for time-division multiplex communication of steam turbine monitoring instrument - Google Patents

Abstract

The invention relates to a method for time division multiplex communication of a turbine monitoring instrument, which divides a time domain into a plurality of small sections of periodic cycle, wherein the time length of each section is fixed; each communication node occupies the serial bus of the bus board in turn according to a convention sequence, each node transmits data to the bus in a specific time period, and the rest nodes which are not in the transmission time period receive the bus data; when a new communication node is added into the bus, the monitoring mode is firstly entered, and then the normal transceiving mode is entered after the sending time period of the node per se is analyzed and judged according to the existing communication condition on the bus; when the existing communication node quits communication, the bus of the original occupied time interval is kept idle, and the main control node is not needed in the whole communication process; compared with the prior art, the invention can realize the communication of each communication node on the serial bus, each node can not generate the communication conflict on the bus, and the efficiency of data communication between the nodes is greatly improved because of adopting a one-transmitting multi-receiving mechanism.

Description

A method for time-division multiplex communication of steam turbine monitoring instrument

[Technical field]

The invention belongs to the technical field of steam turbine monitoring and protection instruments, in particular to a time division multiple communication method for steam turbine monitoring instruments.

[Background technique]

Turbine Supervisory Instruments (TSI Instruments for short) is one of the key devices to ensure the safety of steam turbine operation. The conventional structure of TSI instrument is to insert various modules with different functions in an instrument frame, such as signal monitor module, power module, configuration communication module and so on. The power module supplies power to each module through the frame bus board, and the parameter monitor module receives the measurement signal from the field sensor, and after being processed by the monitor module, displays the monitored parameter value, and generates various alarms or record signal output. A complete set of TSI instruments is composed of these monitor frames, frame busbars, power supply modules, monitor modules, configuration communication modules and field sensors.

The monitor modules in the early TSI instruments work independently. Each monitor module accepts sensor signals from the field, and generates various alarm signal outputs through relays (or transistors). It involves the logical combination of multiple monitoring modules, which requires the user to construct in the way of relay hard wiring or PLC outside the TSI instrument.

With the development of instrument technology and communication technology, TSI instrument began to use the bus board bus of the monitor frame to allow each monitor module (even the intelligent power module) to communicate with each other, and perform operations according to the data and status of its own and other modules to generate Complex alarm signal output, realizing multiple logic combinations across modules, etc. Restricted by the mechanical structure of the TSI instrument, each monitor module in the instrument frame must meet the requirements of live plugging and unplugging, and the bus board bus is usually designed as a serial bus. Since a TSI instrument frame is usually used for monitoring and protection of various parameters of rotating machinery, the monitor modules in the instrument frame must be independent to a certain extent. The failure of any monitor module cannot spread or affect others. monitor module. This requires that the communication between the monitor modules in the TSI frame cannot use the master-slave communication mode commonly used by the serial bus, because once the communication master module fails, the communication of the entire frame may be paralyzed. Since TSI instruments are online monitoring of high-speed rotating machinery, once a module fails, it needs to be able to respond and process quickly. Therefore, the communication between modules must be real-time, efficient and stable, and it must be able to transmit information within a certain time. From one monitor module to other monitor modules. This requires that the communication between monitor modules cannot adopt a preemptive and random communication mode, because this mode cannot ensure that information is delivered from the source node to the target node within a certain time.

[Content of the Invention]

The purpose of the present invention is to solve the above-mentioned deficiencies and provide a method for time-division multiplex communication of steam turbine monitoring instruments, which can realize the communication of each communication node on the serial bus, and avoid the whole communication process caused by the failure of a certain communication node. Communication crashes in the monitor frame and situations where multiple nodes preempt the communication bus causing some nodes to send delays.

In order to achieve the above purpose, a method for time-division multiplexing communication of steam turbine monitoring instruments is designed. The time domain is divided into some small sections of periodic cycle, and the length of each section is fixed; Send data to the bus in a specific period, and other nodes that are not in the sending period receive bus data; when a new communication node joins the bus, it analyzes and judges the sending period of its own node according to the existing communication on the bus.

Preferably, it is cyclic in the time domain, and the cycle of the cycle is determined according to the response time of the TSI instrument. The time in each cycle is divided into segments of equal length, and the number of divided segments is based on the largest node in the TSI framework that may participate in communication. number to decide.

Preferably, each module in the TSI frame occupies the serial bus of the frame bus board in turn according to the sequence of its own node number, and transmits the data of its own node in the time period/phase allocated in each time cycle.

Further, nodes that are not in the sending state can receive data sent by other nodes on the bus, and the communication mechanism of one sending and multiple receiving greatly improves the efficiency of information exchange between nodes.

Further, the bus uses the CAN bus, which conforms to the CAN 2.0B protocol text.

Preferably, each communication node has two working modes: listening and normal sending and receiving; in the listening mode, only data on the bus is received, and in the normal sending and receiving mode, the data is sent to the bus in a certain period of time according to the aforementioned rules, and received in the rest of the period. data on the bus.

Preferably, when a new communication node joins the bus, it first enters the listening mode, and then calculates the appropriate transmission period of its own node according to the transmission rules of the existing nodes on the bus, and enters the normal state after the time value is stable and there are no other faults. Transceiver mode.

Preferably, when the communication node that has sent the sequence quits communication, the allocated time period is in an idle state on the bus.

Further, the communication node in the normal working mode can fine-tune its own sending period according to the communication sequence of the bus.

Further, if a plurality of monitor modules send data at the same time due to an accident, arbitration is performed according to the priority of the information, and the information with a higher level can be successfully sent, and the other information is marked as failed.

Compared with the prior art, the present invention has the following advantages:

(1) the present invention utilizes the TSI monitor frame bus board bus, and can realize the communication of each module in the frame on the serial bus;

(2) There is no main control (or leading) monitor module in the communication process of the present invention, and the communication of the monitor module in the entire monitor frame will not be paralyzed due to the failure of a certain monitor module;

(3) The information generated by each monitor module of the present invention can ensure that the information is sent from the source node to the target node within milliseconds, and there will be no situation that multiple nodes preempt the communication bus and cause some nodes to send delays;

(4) In the communication process of the present invention, any communication node is allowed to join and leave, and the change does not affect the communication of other modules.

[Description of drawings]

1 is a schematic diagram of a time division multiplex communication method of the present invention;

Fig. 2 is the bus data packet sequence diagram of the present invention;

Fig. 3 is the communication realization structure block diagram of the present invention;

Fig. 4 is the communication receiving flow chart of the present invention;

FIG. 5 is a flow chart of communication monitoring according to the present invention.

[Detailed ways]

Based on the time division multiplex communication technology, the present invention realizes that each module in the TSI monitor frame adopts mutual coordination (no master station) on the serial bus to complete real-time, efficient and stable communication. In this article, for the habit of expression, "monitor module" and "communication node" in the monitor framework are two names of the same object in different contexts. In the context of describing communication technology, it is generally called a communication node or simply a node; when describing a physical object in a monitor frame, it is generally called a monitor module.

The invention provides a method for time-division multi-channel communication of steam turbine monitoring instruments. The time domain is divided into some small sections of periodic cycle, and the length of each section is fixed; each communication node occupies the serial bus of the bus board in turn according to the agreed sequence, and each node is in a specific When a new communication node joins, it will analyze and judge the sending period of its own node according to the existing communication situation on the bus.

Preferably, it is cyclic in the time domain, and the cycle of the cycle is determined according to the response time of the TSI instrument; the time in each cycle is divided into segments of equal length, and the number of divided segments is based on the largest node in the TSI framework that may participate in communication number to decide. Each monitor module in the TSI frame occupies the serial bus of the frame bus board in turn according to the sequence of its own node number, and sends the data of its own node in the time period (phase) allocated by each time cycle. Each communication node has two working modes: listening and normal sending and receiving. In the listening mode, only the data on the bus is received. In the normal sending and receiving mode, the data is sent to the bus in a certain period of time according to the aforementioned rules, and the data of the bus is received in the remaining period of time. . The node newly joining the communication first enters the listening mode, and then can calculate the appropriate sending period of its own node according to the sending rule of the existing nodes on the bus, and enter the normal sending and receiving mode after the time value is stable and there are no other faults. When a communication node that has already sent a sequence quits communication, it is in an idle state on the bus for the allocated time period.

In addition, the nodes that are not in the sending state can receive data sent by other nodes on the bus, and the communication mechanism of one sending and multiple receiving greatly improves the efficiency of information exchange between nodes. Use CAN bus, conform to CAN 2.0B protocol text. A communication node in normal operation can fine-tune its own sending period according to the communication sequence of the bus. If multiple monitor modules send data at the same time due to an accident, arbitration will be carried out according to the priority of the information, and the information with a higher level can be sent successfully, and the other information is marked as failed.

Below in conjunction with accompanying drawing and specific embodiment, the present invention is described further below:

The present invention adopts the method of time division multiplex communication, divides the time domain into some small sections of periodic cycle, and the length of each section is fixed. Each communication node occupies the serial bus of the bus board in turn according to the agreed sequence, each node sends data to the bus in a specific period, and the other nodes that are not in the sending period receive the bus data. When a new communication node is added, it will analyze and judge the sending period of its own node according to the existing communication situation on the bus. Each node will not have communication conflicts on the bus, and the efficiency of data communication between nodes is greatly improved due to the use of a one-transmit-multiple-receive mechanism.

As shown in FIG. 2 , T1 is the time period of the data frame cycle on the bus, and is also the time period of each node sending data. The time is determined according to the response time of the monitoring module in the TSI instrument to the external input signal (signal from its own sensor and signals generated by other monitoring modules). T2 is the time when a node sends data. In this communication method, it is stipulated that the data sent by each node is a fixed frame length. T3 is the interval time for data transmission between nodes. T4 is the takt time, the length of which is determined according to the communication cycle period T1 and the maximum number of nodes on the bus. T5 is the adjustment time, generally an integer multiple of T4, T5=eT4, e=1, 2, . . .

T1=(N+e)T4…………Formula 1

In a specific device, N is the maximum number of communication nodes in the TSI framework, and e takes a fixed value of 0 to 2 according to communication needs;

T4 is determined according to the response time Tr and N values required by TSI, but is also limited by the bus rate Baud and the data frame length L.

Each node determines the transmission period (phase) according to its own node number and the transmission time of the highest node number on the bus. Assuming that the highest node number (usually the node with the smallest node number on the bus) is N ₀ , the transmission phase is t ₀ , and the node number of the module is N _x , then the module transmits the phase,

t _x =(N _x -N ₀ )T4+t ₀ ………… Equation 3

There are two working modes for node communication: listening mode and normal sending and receiving mode.

When a new node joins the bus communication, it first enters the listening mode. In this mode, it only listens to the data on the bus, determines the highest-level node, and adjusts its own sending timer until the time phase with the highest-level node on the bus. reach the in-beat (in accordance with Equation 3).

In the normal transceiver mode, data is sent according to a fixed period T1, and its time period is adjusted according to the data frame of the highest-level node on the bus to avoid time drift.

In order to realize the method of time division multiplexing communication, as shown in FIG. 3, there are three mutually independent working processes: communication receiving process 101, communication monitoring process 102 and communication sending process 103; Monitoring and communication sending are driven by T1 and T2 timers respectively; T2's start-up and timing data are controlled by the communication monitoring process. The communication receiving process is shown in Figure 4: record receiving time stamp processing 201 and record receiving data processing 202; the time stamp of the received data is recorded with the internal time of the node, and will be used to calculate the sending time of the node in the future. The calculation principle is as follows (Formula 3).

The communication monitoring process is shown in Figure 5: record local time stamp processing 1, mode judgment 2, listening mode receiving judgment 3, receiving idle count 4, idle duration judgment 5, normal mode (idle on the bus) processing 6, continue Listening processing 7 , time adjustment processing 8 , time stability judgment 9 , normal mode (with nodes on the bus) processing 10 , normal mode reception judgment 11 , normal mode time fine-tuning processing 12 , and continuing normal mode processing 13 . In the listening mode, if there are no other nodes on the bus, after trying the N _idle time, it will actively enter the normal sending and receiving mode. If other node data is received, phase adjustment is performed based on the received timestamp and the local timestamp. If the adjustment value is less than the allowable error for several times in a row, let the module enter the normal sending and receiving mode. In normal transceiver mode, the main thing is to fine-tune the synchronization error with the highest-level node. The communication sending process is relatively simple, and data is sent to the bus every time the timing is up.

To sum up: the present invention discloses a method for time-division multiplexing communication of steam turbine monitoring instruments. The method divides the time domain into some small sections of periodic cycle, and each communication node occupies the serial bus of the TSI bus board in turn according to the agreed sequence. Data is sent to the bus during a specific period, and the rest of the nodes that are not in the sending period receive bus data. The communication node has two working modes: listening and normal sending and receiving. When a new communication node joins the bus, it first enters the listening mode, and then according to the existing communication situation on the bus, it enters the normal sending and receiving mode after analyzing and judging the sending period of its own node. When an existing communication node exits the communication, the bus remains idle for the time period occupied by it, and the existence of the master control node is not required in the entire communication process. Each node will not have communication conflicts on the bus, and because of the one-transmit-multiple-receive mechanism, the efficiency of data communication between nodes is greatly improved.

The present invention is not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principle of the present invention should be equivalent replacement methods, which are included in the present invention. within the scope of protection.

Claims (10)

1. a method for time-division multiplex communication of steam turbine monitoring instrument is characterized in that: the time domain is divided into some small sections of periodic circulation, and the length of each section is fixed; The node sends data to the bus in a specific period, and the rest of the nodes that are not in the sending period receive the bus data; when a new communication node joins the bus, it analyzes and judges the sending period of its own node according to the existing communication on the bus. 2. the method for time-division multiplex communication of steam turbine monitoring instrument as claimed in claim 1, it is characterized in that: the cycle of circulation in time domain is decided according to the response time of TSI instrument, and the time in each cycle is divided into segments of equal length , the number of segments to be split is determined according to the maximum number of nodes that may participate in communication in the TSI framework. 3. the method for time-division multiplex communication of steam turbine monitoring instrument as claimed in claim 2, is characterized in that: each module in the described TSI framework occupies the serial bus of the frame bus board in turn according to the order of its own node number, in each The data of this node is sent in the time period/phase allocated by the time cycle. 4. The method for time-division multiplexing communication of steam turbine monitoring instruments as claimed in claim 1, characterized in that: a communication mechanism of one sending and multiple receiving is adopted, so that nodes not in the sending state can receive data sent by other nodes on the bus. 5 . The method for time-division multiplexing communication of steam turbine monitoring instruments as claimed in claim 1 , wherein the bus uses a CAN bus and conforms to the CAN 2.0B protocol text. 6 . 6. the method for time-division multiplex communication of steam turbine monitoring instrument as claimed in claim 1, is characterized in that: each communication node has two working modes of listening and normal sending and receiving; In the transceiver mode, the data is sent to the bus in a certain period of time according to the aforementioned rules, and the data of the bus is received in the remaining period of time. 7. the method for time-division multiplex communication of steam turbine monitoring instrument as claimed in claim 6, is characterized in that: when new communication node joins bus, at first enter listening mode, then according to the transmission rule of existing node on bus, calculate and obtain The appropriate sending period of its own node, and after the time value is stable and there are no other faults, it enters the normal sending and receiving mode. 8 . The method for time-division multiplexing communication of steam turbine monitoring instruments according to claim 6 , wherein when the communication node that has sent the sequence quits communication, the allocated time period is idle on the bus. 9 . 9 . The method for time-division multiplexing communication of steam turbine monitoring instruments according to claim 6 , wherein the communication node in the normal working mode can fine-tune its own sending period according to the communication sequence of the bus. 10 . 10. The method for time-division multiplexing communication of steam turbine monitoring instruments as claimed in claim 1, characterized in that: if a plurality of monitor modules send data at the same time due to accidental occurrence, then arbitration is carried out according to the information priority level, and the information with high level can be arbitrated. Sending is successful, other information is marked as failed.

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