Substation Automation

In substations, intelligent electronic devices (IED) are replacing legacy electro-mechanical protection relays to monitor substation equipment.

• Integrating IEDs taps into their newly available data, bringing a wealth of benefits:
• Increase engineering personnel efficiency by performing remote device maintenance and configuration
• Improve fault analysis and service restoration by automatically retrieving event files for analysis
• Improve asset management by analyzing operational data and gaining a better understanding of equipment operation
• Reduce maintenance cost by analyzing historical data and performing predictive maintenance instead of periodic maintenance

To gain these benefits utilities need to choose a solution that helps them meet the following challenges:

• Organizational—Most of the IEDs are being installed by equipment protection groups. Most of the data being produced by these IEDs will be useful to different organizational groups
• Technological—In the traditional automation system, a SCADA center connects to a single RTU per substation, using a single protocol, over a single permanent and dedicated link, and collects simple analog and binary data. Modern IEDs use a variety of standard or proprietary protocols to generate data in a large variety of mostly non-standard data formats
• Security—Devices used in a standalone manner, within an enclosed protected perimeter, are inherently secure. IED integration must be performed in a secure, NERC-compliant, manner

To benefit from IED data, a suitable communication infrastructure must be provided to transport data from the devices to the appropriate control centers.

Port switches, terminal servers or frame relay access devices (FRAD) are often considered for the purpose of connecting IEDs to a control center. These simple devices basically provide a means to extend the communication link of each IED across the enterprise network, to the control center.

However, port switches limit the flow of information in a number of ways:

• By extending the communication link to the control center, the protocol complexity is also exported to the control center
• Most devices support a single communication link. The port switch extends this link to a single control center
• Since all IEDs are sharing the same link, the port switch will either require large bandwidth or necessarily introduce higher communication latency