Time synchronization in industrial process control or automation systems

Abstract

The present invention is concerned with improved time synchronization among the devices (2, 10, 20, 30) of an industrial process control system, and in particular of a Substation Automation system, during a temporary absence of a system reference time. Hence, disruption of time-critical protection and control functions due to resynchronization following the temporary absence of the system reference time is avoided, and the availability of the time-critical functions configured on the devices is increased. During normal operation, a device of the system records an offset or discrepancy between the system reference time and an internal local clock of the device for a period of several hours. As soon as the system reference time breaks down, the device starts predicting the offset or drift between its local clock and the unavailable system reference time based on the recorded offset history. As a transient clock master, the device then distributes an approximated or transient system reference time, based on the device's local clock corrected for the predicted offset, to other devices of the system that in turn run time-critical protection and control functions.

Description

technical field [0001] The present invention relates to the field of time synchronization of devices of an industrial process control or automation system, and in particular of a substation automation system of a substation of an electric power transmission system. Background technique [0002] Substations in high and medium voltage power networks comprise primary equipment such as cables, lines, busbars, switches, power transformers and instrument transformers, which are generally arranged in switchyards and / or bays. These primary devices are operated in an automatic manner by a Substation Automation (SA) system. The SA system comprises secondary devices, so-called intelligent electronic devices (IEDs), which are responsible for the protection, control and monitoring of the primary device. IEDs can be assigned to hierarchical levels, namely station level, bay level and process level, the latter being separated from the bay level by so-called process interfaces. The statio...

AI Technical Summary

Problems solved by technology

This can lead to a situation where all devices will have to go through a resynchronization phase

The resynchronization phase implies an interruption of control and protection functions running on the device, as well as a sudden change in the time base of the device, which in turn can cause protection algorithms that rely on time-stamped data snapshots to fail

Images