Substation SCADA integration: gateways, RTUs and time sync

What it is and when you need it

Substation SCADA integration means gathering the signals of relays, bay controllers, meters and field devices in a gateway or RTU, and delivering them to the control center with the protocol, addressing and time stamp it requires. The same work applies in industrial plants that bring their medium-voltage switchgear, protection and metering to a supervisory system.

You need it when building or expanding a substation, when connecting a generation plant or an industrial load to the grid, when replacing the gateway or RTU, and when the control center asks for new signals or changes protocol.

What is included

• Gateways and RTUs Configuration of the channels to the IEDs and of the channels to one or more control centers, with redundancy when the design provides for it.
• Protocols to the control center IEC 60870-5-104 over TCP/IP and serial IEC 60870-5-101; serial DNP3 and DNP3 over TCP/IP.
• Protocols to the devices IEC 61850 MMS, Modbus RTU and Modbus TCP, DNP3 and IEC 60870-5-103 where the device requires it.
• Signal list Each point with its type (single or double-point status, measurement, command, counter), address, scaling, deadband, priority and whether it carries a time stamp.
• Point-to-point tests with the control center, signal by signal.
• Time synchronization SNTP, PTP and IRIG-B, from the GPS clock to every IED.

How we work

1. Planning. We gather the control schemes, the IED list with make, model and firmware, and the control center’s requirements: protocol, addresses, communication profile and signal list format.
2. Signal list. We prepare or clean it up from the schemes and agree it with the client and the control center before configuring. It is the document everything is tested against.
3. Configuration. We configure the IEDs to publish what is needed, the gateway or RTU to collect and convert it, and the channel to the control center with its link parameters.
4. Local tests. With a master simulator we verify every point in the gateway: value, quality, time stamp and scaling. Signals that originate in protection are generated by injection from the Omicron CMC 356 or with the IED’s test modes.
5. Point-to-point tests with the control center. Signal by signal, with the operator online: statuses, alarms, measurements and commands. Real commands are executed only with the authorization of operations.
6. Time synchronization. We verify that each device takes the intended reference and that events reach the control center with the correct time.
7. Report. The signal list with the result for each point, and a backup of the whole configuration.

Standards and criteria in substation SCADA integration

IEC 60870-5-101 and -104 define the telecontrol profile most used between substations and control centers; IEEE 1815 defines DNP3. Modbus follows the public specification of the Modbus Organization and carries no quality or time stamp of its own, so it is best limited to measurements and statuses of auxiliary equipment. Each control center also sets its own interoperability profile: object types, addresses, link timers and redundancy. That document overrides any default value.

For time synchronization, IRIG-B follows IRIG Standard 200 and is distributed over dedicated wiring; SNTP travels over the same data network and its accuracy depends on that network; PTP, per IEEE 1588 with the power utility profile of IEC 61850-9-3, is used when the design calls for higher accuracy. The required accuracy is defined by the project specification.

Signaling is only useful if it reflects the true state of the yard equipment. That is why we check that statuses such as breaker pole discrepancy, or alarms from the on-load tap changer voltage regulator, arrive from their real source and not only from a simulation.

What you receive

• The final signal list, with address, scaling and the result of the point-to-point test.
• A backup of the gateway or RTU configuration and of every modified IED.
• The test record with the control center, with open items and their owners.
• The time synchronization and communications diagram.
• The report.

Why Tiza Group

• One team responsible from start to finish, from the signal list to the last test with the control center.
• Field experience from design through commissioning, in medium, high and extra-high voltage substations and in industry.
• Experience with the main brands: Siemens, Schneider Electric, SEL, ABB, GE, Fanox, NOJA Power and Efacec.
• Remote configuration capability for adjustments and new signals after handover.

This service is part of our control, protection and communications configuration, together with IEC 61850 configuration. To discuss your project, contact us.