Enclosed GIS Substations Offer Utilities Greater Protection from Malicious Criminal Attacks

Utilities are increasingly addressing the potential for intentional physical attacks and other criminal acts against substations. Such attacks have caused serious damage with long-lasting effects.

The latest grid calamity occurred Dec. 4 in Moore County, North Carolina, where vandals drove up to two Duke Energy substations, breaching a gate in one case, and shot into the stations. The damage to electrical equipment resulted in 45,000 customers, almost everyone in the county, losing power in freezing weather.

The attack is similar to the sophisticated sniper attack in 2013 on the Metcalf Transmission Substation in rural Santa Clara County, California. In that attack against a Pacific Gas and Electric substation, someone cut nearby telephone cables and then shot out 17 transformers that served Silicon Valley. That crime caused $15 million in damage and remains unsolved.

Because such strikes are rare, more attention tends to be focused on cybersecurity threats. That may change now.

 

Greater Security and Resiliency

It’s impossible to design a substation that is 100% safe against a determined criminal attack. But many utilities are turning to enclosed gas-insulated switchgear (GIS) substations for greater security, as well as the resilience to withstand and rapidly recover from severe weather and other disruptions.

It is possible with a sufficiently hardened facility and a layered approach to physical security to make malicious damage less severe, prolong service and restore service more quickly. Such substations serving critical infrastructure also can be engineered and constructed to provide the necessary reliability for increasing public demands.

GIS in an enclosure or building is inherently resistant to a high-powered rifle shot or other projectile. The high-voltage and medium-voltage switchgear are physically protected within a hardened building. External power transformers can be shielded with walls, and the open side of each transformer bay can accommodate ballistic screening, if needed.

A GIS substation’s smaller, enclosed area makes it easier to use surveillance equipment to monitor substation security at a lower cost than a typical air-insulated station. GIS substations also can provide an expanded security perimeter with hardened barriers. A station’s design can incorporate electronic surveillance and intruder detection systems.

An additional benefit of infrastructure hardening with GIS substations at strategic locations is that they can reduce the consequences of damages from severe flooding and wind at critical substations. The substations can be raised as well as being placed inside a hardened building.

 

Key Steps

The key to designing a hardened substation is to methodically assess what could happen and the vulnerabilities within the substation that need to be addressed. In order to effectively prepare for potential threats to substations, utilities need to:

• Identify the major physical threats and their characteristics
• Identify vulnerable assets with respect to the identified threats
• Assess potential effects of the threats
• Maintain an ongoing awareness of new risks and evolving threats

Potential threats, for example, might include targeting substation personnel, puncture and rapid leaking of insulating fluids and destruction of insulators or bushings for high-voltage equipment. These threats affect workers’ lives, restoration times for equipment, power for critical loads and public safety.

Most catastrophic damage to substations can be effectively prevented by using gas-insulated switchgear as part of the design of substations that are critical to the electric grid and vulnerable to major threats. GIS substation physical security advantages include:

• Equipment inside a hardened building or in an underground or elevated structure, eliminating line-of-site for ballistic attacks
• Expansion of the security perimeter
• Easily disguised and aesthetically pleasing structure with no overhead line entry
• Routing transmission or distribution lines underground to protect line terminations
• Switchgear is completely enclosed with fire protection
• Transformers and reactors can be enclosed and covered with grating overhead to minimize air assault
• Relay control rooms can be located at the interior of the complex to enhance protection

 

Conclusion

Criminal physical attacks on substations have the potential to cost a utility millions of dollars in financial losses from damage to equipment, theft of materials or equipment and power outages. Such attacks also threaten lives.

GIS substations reduce potential for safety risks and damage. Reliability is improved, life cycle costs are lowered, security and, most importantly, public safety are increased. This substation-in-a-box is better protected from criminal attacks.

 

Article originally published on the POWER Engineers website.