Seismic-Resilient Bulk Power Grids: Hazard Characterization, Modeling, and Mitigation

The operation of the electricity delivery infrastructure is environmentally driven and vulnerable to a wide range of high-impact low-probability (HILP) hazards. Among different classes of HILP disasters, earthquakes are one of the most unpredictable hazards which may lead to widespread disruptions of mission-critical services and infrastructures. This article introduces a comprehensive framework for modeling and characterization of seismic hazards, vulnerability assessment of electric systems to the earthquake, and corrective actions and mitigation strategies ensuring operational resilience. The Monte Carlo simulation is employed to produce a realistically large set of possible earthquake scenarios to capture the stochastic nature of seismic hazards. An inclusive approach is then introduced based on the fundamental principles of fragility curves to assess the vulnerability of power generation facilities in the face of HILP earthquakes. A new seismic risk metric is suggested that takes into account both hazard and vulnerability probabilities, as well as the financial consequences due to postquake disruptions in power generation stations. Along with the generation redispatch strategy as a conventional mitigation solution following a nontrivial contingency, a new mitigation strategy centered on corrective network topology control is formulated to maximize the load outage recovery following HILP disruptions. The proposed decision support tool enables a swift restoration and improved resilience in dealing with the aftermath of the HILP earthquakes. Efficacy of the proposed framework is numerically analyzed and verified on both the IEEE 57-bus and IEEE 118-bus test systems.

I. Introduction

Extreme natural disaster events, such as floods, windstorms, tsunamis, and earthquakes, have caused catastrophic damages on the power energy delivery infrastructure [1]. According to [2], 58% of all the U.S. grid outages in the 10-year time interval of 2003–2012 are driven by the weather-caused high-impact low-probability (HILP) events resulting in an estimated $18–33 billion annual loss. Among different HILP disasters, earthquakes are one of the most unpredictable and disastrous hazards [3], which may lead to widespread disruptions in electrical power grid and its critical infrastructure. On January 17, 1994 the Northridge earthquake struck the city of Los Angeles and surrounding areas resulting in 2.5 million customers out of power [4]. The Great Hanshin earthquake occurred a year later, affecting the city of Kobe, Japan. Twenty fossil-fired power generation units, six 275-kV substations, and two 154-kV substations were damaged resulting in approximately 2.6 million customers affected by electricity outages [5]. On October 17, 1989, the Loma Prieta earthquake in the greater San Francisco Bay Area in California caused 63 deaths, 3757 injuries, and$6 billion in property damage [6]. Nearly 2 million customers were disconnected immediately from the Los Angeles power network following the 1994 Northridge earthquake; the estimated economic loss due to the Northridge earthquake was exceeding $49 billion [7]. On May 18, 2008, the Wenchuan earthquake caused extensive damage to the local power transmission and distribution systems in Sinchuan province, China, where approximately 900 substations and 270 transmission lines of the State Power Grid were damaged. It has been estimated that at least 90% of the damage could have been avoided by adopting new guidelines for seismic design, planning, and adaptation [8]. Approximately 90% of Chileans did not have electricity immediately following the 8.8 () earthquake on February 27, 2010. The event caused the largest power transmission company in Chile to have direct losses of approximately$6.5 billion [9]. The devastating Tohoku Chiho Taiheiyo-Oki earthquake on March 11, 2011 and its aftershocks damaged 14 power plants, 70 transformers, and 42 transmission towers, among other failures. The outage stemming from the event affected 4.6 million residents and the April 7 aftershock affected an additional 4 million [10]. Recently, on November 30, 2018, a magnitude 7 earthquake rocked southern Alaska resulting in downed power lines, collapsed roads, and fleeing population [11].