Multi-node synchronization sampling and data transmission method

Abstract

The invention provides a multi-node synchronous sampling control and data transmission method, the steps are as follows:(1) an overall synchronizer that matches with the upper layer data processing equipment and the process variable acquisition control equipment (DAE) is constructed, the equipment produces an overall synchronous signal S1 by utilizing an outer sync source or a local timer; (2) the overall synchronous signal is accessed to one or more data communication equipment (DCE), which produce a synchronous signal S2 for each accessed process variable acquisition control equipment; (3) the absolute time scale in the signal S1 and the overall sampling counter are utilized to realize the secondary synchronous sampling on the process variable among the data communication equipment; (4) the acquisition control equipment (DAE) for acquiring and outputting the process variable detects the synchronous signal and order data after receiving the signal S2; (5) the acquisition control equipment dynamically adjusts the start time of the S2 signal according to Delta ti and realizes the long-distance multinode synchronous sampling.

Description

1. Technical field [0001] The invention relates to a method for synchronous sampling and real-time data transmission among multiple data acquisition nodes distributed in different places. Especially in the field of power system protection and industrial control where distributed acquisition control and centralized data processing are required, data sampling requires strict synchronization, sampling data requires real-time transmission, and time delay is fixed. Specifically, the present invention is a multi-node synchronous data acquisition and real-time transmission method. 2. Background technology [0002] In the field of power system relay protection and industrial process control, in order to accurately retain the phase information of the signal, or to conduct accurate timing analysis on asynchronous events, it is necessary to collect a certain group of process variables at different locations synchronously at equal intervals, in order to improve the system Real-time pro...

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Problems solved by technology

[0012] due to f 0 , f a , N is an integer, when the sampling rate N is higher, the above formula cannot be exactly equal, and the difference between different nodes is due to f a Different and frequency drift, it is actually impossible to achieve synchronous and equally spaced sampling

[0013] 2. The synchronous sampling method based on IEEE1588 requires network hardware interfaces and switching devices that support the IEEE1588 protocol, which increases additional costs

Moreover, because IEEE802.3 has requirements for Ethernet transmission distance and network transmission delay, it is not suitable for synchronous acquisition and control among multiple nodes that are physically distributed far away.

IEEE1588 starts the synchronization process once per second. After the clock synchronization fails, re-synchronization needs to repeatedly calculate the relative error Δt of the clocks on both sides, and the synchronization delay is long.

[0014] In addition, when the high-speed multi-node acquisition and control device is connected to the same master control node, network conflicts will intensify during heavy loads, affecting real-time data transmission, and it cannot be guaranteed that each sampled data will be transmitted to the data processing terminal under a fixed delay

[0015] 3. The GPS synchronization method is affected by the number of satellites captured by GPS, as well as the natural environment and social environment and other factors, and requires corresponding hardware support, additional data transmission channels, and high cost

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