The System Operator Transmission Owner Code (STC) has been amended recently to include, for future requirements, the transfer of elements of Phasor Monitoring Unit (PMU) data directly to the National Grid System Operator. SSEN presently views PMU data on the Secondary Operational Network (2nd OTN) by directly contacting the PMU. SSEN has no facility to actively gather the PMU data, nor is it possible to make elements of PMU information available to a third party.
Objectives
Produce a report that outlines the different system architectures options available for managing PMU information.
Learnings
Outcomes
The study found that TOs usually have the necessary sensor devices, telecommunications infrastructure and data centre capacity to fulfil their short-term and medium-term goals in relation to phasor instream data processing (IDP); namely, the storage of synchrophasor data for analysis and planning, and the sharing of data to National Grid Electricity System Operator
(NGESO) as required by the System Operator Transmission Owner Code (STC) STCP27-01 standard (before the end of 2026).
Furthermore, existing protocols/standards and architecture conventions should support their short-term goals and, in the medium-term, satisfy the base requirement of sharing data to NGESO. However, existing synchrophasor-specific standards are not necessarily the best fit for granular, secure sharing of data externally; nor for metrology systems that may increase
significantly in scale in the future.
In our review of the transport technologies that can be applied to synchrophasor data, we have the following key findings.
A conventional Phasor Monitoring Unit (PMU) with phasor data concentrator (PDC) arrangement in existing architecture can meet the short-term functional requirements, but has recognised limitations with regard to flexibility, scalability, and security.
STTP is expected to become the standard for PMU and synchrophasor data transport. However, it is potentially 5-10 years away (protocol ratification and vendor adoption). At this stage (2020) there are potential deficiencies in the mechanism by which it operates.
MQTT provides opportunities to transport IEEE C37.118 data in more flexible, scalable, secure and reliable ways. MQTT isn’t a 'standardised' approach for synchrophasors, however, as well as being utilised by many large organisations such as IBM and Amazon Web Services (AWS), it has also been used by several utilities, e.g. ESB Networks and XM Energy.
Software Defined Networks, including SD-WAN, provide an opportunity to securely transport virtually any data type. This is an important solution to the problem of the heterogeneous nature of Intelligent Electronic Devices (IEDs), and the practicalities of keeping such IEDs up-to-date with security patches (if they exist) in a live operational environment.
The project report concludes with recommendations based on the options available, giving an indication on the steps required, by breaking developments into three phases of deployment:
1. Phase 1 (0-2 years): Deliver an in-house post-event analysis capability using existing protocols and infrastructure as well as open-source tools;
2. Phase 2 (by end of 2026): Deliver real-time data transfer to NGESO plus support for near- and real-time applications, preferably using MQTT. This can be deployed in parallel with the Phase 1 infrastructure, allowing for a phased transition to a modern, flexible architecture.
3. Phase 3 (6-10+ years): Migrate TOs IDP system onto a more sustainable, future-proof architecture, probably based on STTP and IEC 61850 standards.
This phased approach mitigates the risk associated with standards that are not yet adopted by industry, such as STTP, whilst delivering TOs short and medium-term goals.
Lessons Learnt
A new synchrophasor standard called Streaming Telemetry Transport Protocol (STTP) is on the horizon but may take several years to be fully ratified and adopted by vendors. A highly flexible interim protocol called Message Queuing Telemetry Transport (MQTT) is discussed in the project report which can be utilised by Transmission Operators (TOs) to provide the more granular, secure, and scalable sharing required in the long-term. STTP and MQTT could be investigated further, and trialled, to build on the learning of this project.
Network Operators should be aware of any emerging standards and developments surrounding phasor data processing as this is an emerging and innovative topic. Particular note should be taken of ongoing developments to the System Operator Transmission Owner Code (STC) set by the electricity system operator which will dictate the required phasor functionalities for Transmission Operators.
