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Securing Tomorrow's Grid (Part I)

Protecting smart systems against cyber threats.

Fortnightly Magazine - July 2011

(typically 20 samples per second) across an entire grid interconnect, providing operators a real-time, high-quality view of transmission system state. PMUs accurately measure parameters such as voltage timing (phase angle) differences across the transmission network that reveal areas of strain and potentially dangerous anomalies such as oscillations, and clarify the current state of the grid in ways that aren’t available from traditional sensors.

Phasor data concentrators (PDCs) collect data from multiple PMUs across wide regions of the grid. The data is then analyzed and used to inform advanced decision support systems, enabling operators to pinpoint problems on the grid and quickly receive actionable information to manage grid operations, identify potentially unstable conditions, and restore the system after an outage. Phasor applications may also collect other external environmental data (such as weather or traffic data) to provide a more complete picture of system disturbances. Because PMUs are widely distributed throughout a region or interconnect, utilities can share data across organizations through implementation of a phasor gateway. With this fast, accurate, wide-area system data, operators can monitor stability and grid dynamics over a broad area in real time, and operate the power system closer to its limits, which increases asset utilization and reduces congestion costs.

Phasor data information flow is continuous and time sensitive—it must reach the point-of-use typically within two seconds. Late-arriving data is either discarded or passed on to a data store where it has benefits beyond real-time use: analysis of PMU data stores can improve future state estimation and aid in system or event analysis after the fact. Depending on how and where they’re deployed and used, many PMUs might be considered a critical cyber asset under North American Electric Reliability Corp. (NERC) critical infrastructure protection standards.

A critical component of PMU technology is the use of GPS signals for time-synchronization. Yet GPS signals can be jammed or spoofed by a hacker with moderate expertise and resources. Because PMU data must arrive at the point-of-use within one to two seconds to be relevant, cyber security solutions that protect PMU data communications must not introduce any delay in transmission. PMU data is shared between many entities and across geographical boundaries, making security measures at connecting gateways critical. The aggregated system information that passes through connecting gateways would be highly valuable to electricity market participants, also making it an attractive target for malicious actors. The potential to compromise the data and cause system instability could further motivate malicious actors interested in creating fear or leveraging their access to extort money.

Figure 6 outlines potential impacts of a successful cyber attack against PMU technology used for wide area monitoring of the transmission system.

Protecting Transmission

The following mitigations are selected examples of good practices for security of wide-area situational awareness systems operating on the transmission network— i.e., synchrophasors:

• Security controls should have minimal impact on the synchrophasor system, and in no way prevent its primary mission.

• Security controls should minimize the impact of adverse events on the quality of service for synchrophasor communications and functions.

• No external entity should have