2

Data Communication

2.1 Introduction

Data communication systems are essential in any modern power system and their importance will only increase as the Smart Grid develops. As a simple example, a data communication system can be used to send status information from an Intelligent Electronic Device (IED) to a workstation (human–machine interface) for display (see Chapter 6). Any co-ordinated control of the power system relies on effective communications linking a large number of devices.

Figure 2.1 shows a model of a simple point-to-point data communication system in which the communication channel is the path along which data travels as a signal. As can be seen from Figure 2.1, the communication channel could be a dedicated link between the Source and Destination or could be a shared medium.

Using the power system as an example, some possible components of this model and the associated physical devices are listed in Table 2.1.

Communication channels are characterised by their maximum data transfer speed, error rate, delay and communication technology used. Communication requirements for commonly used power systems applications are given in Table 2.2.

2.2 Dedicated and shared communication channels

Certain applications require the transmission of data from one point to another and other uses may require the transmission of data from one point to multiple points. When a secure communication channel is required from one point to another, a dedicated link is used exclusively by the ...

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