Natural disasters can cause large blackouts. Research into natural disaster impacts on electric power systems is emerging to understand the causes of the blackouts, explore ways to prepare and harden the grid, and increase the resilience of the power grid under such events. At the same time, new technologies such as smart grid, micro grid, and wide area monitoring applications could increase situational awareness as well as enable faster restoration of the system. This paper aims to consolidate and review the progress of the research field towards methods and tools of forecasting natural disaster related power system disturbances, hardening and pre-storm operations, and restoration models. Challenges and future research opportunities are also presented in the paper.

Research on Resilience of Power Systems Under Natural Disasters—A Review

Resilience to high impact low probability events is becoming of growing concern, for instance to address the impacts of extreme weather on critical infrastructures worldwide. However, there is, as yet, no clear methodology or set of metrics to quantify resilience in the context of power systems and in terms of both operational and infrastructure integrity. In this paper, the resilience “trapezoid ” is therefore introduced which extends the resilience “triangle” that is traditionally used in existing studies, in order to consider the different phases that a power system may experience during an extreme event. The resilience trapezoid is then quantified using time-dependent resilience metrics that are specifically introduced to help capture the critical system degradation and recovery features associated to the trapezoid for different temporal phases of an event. Further, we introduce the concepts of operational resilience and infrastructure resilience to gain additional insights in the system response. Different structural and operational resilience enhancement strategies are then analyzed using the proposed assessment framework, considering single and multiple severe windstorm events that hit the 29-bus Great Britain transmission network test case. The results clearly highlight the capability of the proposed framework and metrics to quantify power system resilience and relevant enhancement strategies.

/pdf/metrics-and-quantification-of-operational-and-infrastructure-4negwoe525.pdf

Metrics and Quantification of Operational and Infrastructure Resilience in Power Systems

Natural disasters such as Hurricane Sandy can seriously disrupt the power grids. To increase the resilience of an electric distribution system against natural disasters, this paper proposes a resilient distribution network planning problem (RDNP) to coordinate the hardening and distributed generation resource allocation with the objective of minimizing the system damage. The problem is formulated as a two-stage robust optimization model. Hardening and distributed generation resource placement are considered in the distribution network planning. A multi-stage and multi-zone based uncertainty set is designed to capture the spatial and temporal dynamics of an uncertain natural disaster as an extension to the traditional ${N}$ - ${K}$ contingency approach. The optimal solution of the RDNP yields a resilient distribution system against natural disasters. Our computational studies on the IEEE distribution test systems validate the effectiveness of the proposed model and reveal that distributed generation is critical in increasing the resilience of a distribution system against natural disasters in the form of microgrids.

Robust Optimization-Based Resilient Distribution Network Planning Against Natural Disasters

Continuously expanding deployments of distributed power-generation systems (DPGSs) are transforming the conventional centralized power grid into a mixed distributed electrical network. The modern power grid requires flexible energy utilization but presents challenges in the case of a high penetration degree of renewable energy, among which wind and solar photovoltaics are typical sources. The integration level of the DPGS into the grid plays a critical role in developing sustainable and resilient power systems, especially with highly intermittent renewable energy resources. To address the challenging issues and, more importantly, to leverage the energy generation, stringent demands from both utility operators and consumers have been imposed on the DPGS. Furthermore, as the core of energy conversion, numerous power electronic converters employing advanced control techniques have been developed for the DPGS to consolidate the integration. In light of the above, this paper reviews the power-conversion and control technologies used for DPGSs. The impacts of the DPGS on the distributed grid are also examined, and more importantly, strategies for enhancing the connection and protection of the DPGS are discussed.

/pdf/distributed-power-generation-systems-and-protection-3g8dq2p3up.pdf

Distributed Power-Generation Systems and Protection

This paper focuses on the role of networked microgrids as distributed systems for enhancing the power system resilience against extreme events. Resilience is an intrinsically complex property which requires deep understanding of microgrid operation in order to respond effectively in emergency conditions. The paper first introduces the definition and offers a generic framework for analyzing the power system resilience. The notion that large power systems can achieve a higher level of resilience through the deployment of networked microgrids is discussed in detail. In particular, the management of networked microgrids for riding through extreme events is analyzed. In addition, the merits of advanced information and communication technologies (ICTs) in microgrid-based distributed systems that can support the power system resilience are presented. The paper also points out the challenges for expanding the role of distributed systems and concludes that networked microgrids in particular provide a universal solution for improving the resilience against extreme events in Smart Cities.

Networked Microgrids for Enhancing the Power System Resilience

Interconnected power grids throughout the world are very reliable but occasionally suffer massive blackouts with multibillion dollar costs to society. Cascading failures present severe threats to power grid reliability, and thus reducing their likelihood, mitigation and prevention is of significant importance. This paper is one in a series presented by Cascading Failures Task Force, under the IEEE PES Computer Analytical Methods Subcommittee (CAMS) with primary focus on mitigation and prevention of cascading outages. The paper presents the basic methodologies for mitigation, summarizes currently deployed special protection schemes, and lists cases of successful and unsuccessful mitigation of cascading outages and lessons learned. Future developments and challenges in the area of mitigating cascading outages are also discussed.

Mitigation and prevention of cascading outages: Methodologies and practical applications

This paper presents an improved interdiction model to identify maximal electric grid attacks The contribution of the model is that it incorporates both short-term (seconds to minutes) and medium-term (minutes to days) impacts of the possible attack The medium-term impacts are examined by an interdicted dc optimal power flow model The short-term impacts are addressed by a cascading outage analysis model that uses a set of sequentially applied checkers to perform the simulation of the cascading outage events and assess the short-term impacts of a blackout subsequent to specified terrorist attacks An integer programming heuristic is applied that can utilize standard optimization software (eg CPLEX) to solve master problems generated by the heuristic The proposed model has been verified using the IEEE 300-Bus Test System and IEEE RTS 96 Test System Discussions of the results and future research plans are also presented in this paper

Interdiction Analysis of Electric Grids Combining Cascading Outage and Medium-Term Impacts

Electric power grids throughout the world continue to suffer from massive blackouts with multibillion dollar cost to society. Most large blackouts involve a sequence of cascading outages. Once a critical component of a power system failed, the outages including generator and load trips can sequentially spread and frequently lead to large blackouts. Some of our previous work has proposed a sequential outage checker based cascading outage analysis model. In this paper, an improved cascading outage analysis model is proposed. Four outage checkers, namely the transient stability checker, the frequency outage checker, the line outage checker and the voltage outage checker are implemented. The outage checkers are operated according to a newly proposed algorithm to determine the status of the resulting operating state or equilibrium. Detailed modeling of the protection schemes, including rotor angle deviation relays, under frequency load shedding schemes, under/over voltage relays and over current relays are implemented. A case study of the improved cascading outage model using the IEEE 118-bus system and the IEEE 300-bus system is also presented.

Case study of an improved Cascading Outage Analysis model using outage checkers

/pdf/cascading-outage-analysis-using-sequential-outage-checkers-5c4h0hf7dy.pdf

Yezhou Wang

Papers

Research on Resilience of Power Systems Under Natural Disasters—A Review

Mitigation and prevention of cascading outages: Methodologies and practical applications

Interdiction Analysis of Electric Grids Combining Cascading Outage and Medium-Term Impacts

Case study of an improved Cascading Outage Analysis model using outage checkers

Cascading Outage Analysis Using Sequential Outage Checkers