Synchrophasor was initially deployed in transmission systems and bulk power systems. However, as utilities strive for the ambitious goal of climate neutrality, significant changes are occurring at the grid edge, writes Nokia’s Hansen Chan.
Synchrophasor is a time-synchronized measurement system that provides real-time situational awareness of the power grid. Through high-frequency reporting (up to 60 measurements per second), it offers much better visibility into grid conditions and power flows than traditional SCADA, allowing utilities to look for subtle changes in the grid early on. It is made up of phase measurement units (PMUs) installed in the field and in substations for measuring power line data, and phasor data concentrators (PDCs) that work as data collectors in substations, control centres and data centres.
Synchrophasor was initially deployed in transmission systems and bulk power systems. However, as utilities strive for the ambitious goal of climate neutrality, significant changes are occurring at the grid edge. These include more distributed energy resources (DERs) and storage, more customer-initiated demand response and more EV charging points connected to the distribution system. Consequently, there is growing interest in deploying PMUs at the grid edge to analyze grid unbalance, detect instability and monitor DER generation. These PMUs are also known as distribution PMUs (D-PMUs) or micro-PMUs (μPMUs).
The underpinning of synchrophasors is a high-speed communication network that connects PMUs to PDCs at different locations. There are three major challenges in deploying synchrophasors at the grid edge:
- PMUs installed on poles and in low-voltage substations do not usually have fiber or microwave access. Broadband wireless technology such as LTE is a viable access option for the field area network (FAN).
- The PMU needs to send measurement data to multiple PDCs. The traditional approach is to send multiple copies of this data, which requires more bandwidth and puts strain on the wireless access link. The use of IP multicast defers data replication to the network core, where there are abundant fiber and bandwidth resources.
- The FAN needs to be service-centric to simultaneously support other grid applications such as voltage VAR optimization (VVO) and fault detection, isolation and restoration (FDIR).
To address the FAN challenge, Nokia proposes a service-centric converged FAN that can carry multiple grid applications, as shown in Figure 1. The cornerstone of the converged FAN is an LTE router connected to a private or commercial LTE network or both. It runs grid application-aware IP/MPLS VPNs over the wireless interface – for example, a VPN for a PMU connecting to an IP multicast domain. This allows the PMU to send only one copy of measurement data. The network will replicate this data for distribution to designated PDUs in the core network, thereby optimizing radio bandwidth utilization. Additionally, the router can use a second VPN for GOOSE communications between a switch controller and automation controller and another VPN for advanced metering infrastructure (AMI) data backhaul.
With a converged FAN, utilities can consolidate the existing hodgepodge of FANs built on legacy, proprietary and narrowband radio technologies on one network. A converged FAN will reduce operations costs today while meeting the needs of the new data-intensive synchrophasor application, latency-sensitive GOOSE communications and many other applications. It is also optimized for new IP-based grid innovations and will continue to be an integral component of the carbon reduction strategy for many years to come.
About the author
Hansen Chan is with IP Product Marketing at Nokia with a special focus on digital industries and government. With over 25 years of protocol testing, network consulting and product management experience, he’s a go-to speaker at international industry conferences. When he’s not talking networks, he’s reading up on history and religion, and listening to Baroque and 20th-century classical music.
Tweet him @hchan888
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