Planning and Protection Approach to Substation Physical Security

Physical attacks on electrical substations in December 2022 have escalated alarms about the vulnerability of the power grid.

Saboteurs shot into two Duke Energy substations in Moore County, North Carolina, on December 3, shutting down power in freezing temperatures to 45,000 customers, almost everyone in the county. Then, on a frigid cold Christmas Day in Washington, vandals attacked four substations of Tacoma Public Utilities and Puget Sound Energy, knocking out power to 14,000 customers.

What do utilities need to do to protect their substations and the integrity of the electrical grid?

Risk assessment

It’s common for utilities to approach security for their substations based on risk rather than a “one size fits all” strategy. Rightly so, they focus security measures on those assets that present the highest risk to the grid. They assess risk, threat and vulnerability as well as create a physical security plan for each station that may compromise the integrity of the bulk electric system if damaged.

The recent attacks targeted distribution substations that provide power to our homes and schools, which usually have little effect on the overall integrity of the high voltage electrical grid if damaged. Knocking out the Washington substations did not create a blackout or major disturbance; however, it did disrupt the lives of tens of thousands of people.

How utilities respond to physical threats like the examples above can seriously affect costs, operations and other decisions about how substations are constructed. Utilities looking for advice on security measures are sure to find it, but the type of advice may depend on who you ask. For example:

• Civil engineers will likely focus on the physical construction of buildings or barriers such as high-strength wall rather than a chain-link fence to provide a visual and physical barrier.
• Land acquisition experts may suggest avoiding building a substation next to a hill as a bad actor can simply shoot over it from the top of the hill.
• Network communication engineers may suggest coordinated communications for fence alarms, door alarms and security cameras.
• Substation design engineers may suggest applying special substation equipment such as gas insulated substations that are compact and typically installed inside buildings or have hardened exteriors, providing a higher level of security.
• Cybersecurity engineers will look to design highly secured communication systems that stop hackers and defend the grid from cyberattacks.

All of this advice, in fact, is sound. But which should be deployed; one, several or all? Reacting to current events like those described here and implementing everything may not be the best, or most cost-effective, answer. This is where electrical engineers focused on electrical protection and system planning engineers can help.

CIP standards

The North American Electric Reliability Corporation, or NERC, has put in place a set of mandatory security standards that utility companies connected to the grid must follow. The Critical Infrastructure Protection (CIP) standards establish a reference set of security measures.

NERC Reliability Standards define the reliability requirements for planning and operating the high-voltage electrical grid and are developed with an approach focused on system performance and risk management. Select CIP standards such as CIP-014 call for assessment of high-voltage transmission stations that if physically attacked could result in instability, uncontrolled separation or cascading within an interconnection. Planning and protection engineers are familiar with performing this assessment to identify stations that would require physical security upgrades, as well as designing those upgrades.

In addition to this standard, NERC has developed the transmission planning standard TPL-001-4, being updated to TPL-001-5 next summer, which requires an annual system reliability assessment. This manner of planning study, which is focused on the stability of the greater bulk electric system, can be used to identify the level of customer load that can be interrupted during simulated outage scenarios to prioritize project improvements.

Additionally, system impact studies, which are usually completed more often than TPL studies, determine how the system may be affected by the interconnection of a new generation resource or load. All these studies also provide insights into system reliability and stability.

Planning and protection

With grid modernization becoming increasingly important, the planning and protection disciplines are becoming more closely tied together. Both disciplines identify protection levels for substations and transmission lines and identify gaps that could cause operational issues in the bulk electric system.

After planning engineers identify the risks, protection engineers focus on the relays themselves, creating settings that continuously monitor the system looking for faults or other anomalies. If a relay detects a fault, the relay will trip the breakers comprising the zone of protection, thereby removing the fault from the system. This improves system reliability and keeps customers online.

Not surprisingly, many of the solutions that harden a substation against malicious threats also protect it from natural disasters. A tornado or flood could just as easily hit a substation and have the same consequences as malicious attack.

In short, utilities need to be working to identify these types of risks and threats to their system operation and their capability to serve the load demand of their customers. System risks need to be identified and mitigated. Planning engineers who are familiar with and capable of performing these studies can prioritize and phase system upgrades to address identified issues. Protection engineers then implement solutions to mitigate grid vulnerabilities, thereby increasing grid resiliency.