Quantitative Resilience Assessment under a Tri-Stage Framework for Power Systems

Han Zhang, Hanjie Yuan, Gengfeng Li, Yanling Lin
2018 Energies  
The frequent occurrence of natural disasters and malicious attacks has exerted unprecedented disturbances on power systems, accounting for the extensive attention paid to power system resilience. Combined with the evolving nature of general disasters, this paper proposes resilience assessment approaches for power systems under a tri-stage framework. The pre-disaster toughness is proposed to quantify the robustness of power systems against potential disasters, where the thinking of area division
more » ... ng of area division and partitioned multi-objective risk method (PMRM) is introduced. In the case of information deficiency caused by disasters, the during-disaster resistance to disturbance is calculated to reflect the real-time system running state by state estimation (SE). The post-disaster restoration ability consists of response ability, restoration efficiency and restoration economy, which is evaluated by Sequential Monte-Carlo Simulation to simulate the system restoration process. Further, a synthetic metric system is presented to quantify the resilience performance of power systems from the above three aspects. The proposed approaches and framework are validated on the IEEE RTS 79 system, and helpful conclusions are drawn from extensive case studies. Power system resilience assessment can measure the capability of a system to maintain stable operation status and to provide sufficient power supply against disasters. The current methods of resilience assessment are mainly divided into three categories [10]: the simulation-based method [11] [12] [13] , the analytic method [14] , and the statistical analysis [15, 16] . Panteli [17] developed the fragile model of the transmission system and presents a comprehensive assessment methodology for multi-temporal and multi-regional resilience. Wang [18] provided a quantitative analysis of the temperature and water availability effects on resilience of the power system. Four indices were introduced by Liu [19] to measure the grid resilience from different perspectives including fragility, survivability and restoration. The resilience trapezoid is discussed by Panteli [20], based on which the authors put forward a resilience metric system called "ΦΛEΠ". Considering the nature of disastrous events, it is reasonable to divide their effect on the power system into different stages: before, during and after the disturbance. That is because the main issues to be emphasized and the operating characteristics are quite different for these stages. The prevention, resistance and post-disaster restoration work against disasters is a long-term and multi-stage process, so it is of much difficulty to recognize and study the power system resilience as a single entity, which will expand the scale and increase the complexity of the research. Combined with the resilience curve, Panteli [6] firstly divides the stages of power system resilience, and gives the features that a resilient power system must possess at each stage. As an important part of resilience research, resilience should also be evaluated by stage to reduce the difficulty, regarding the evolutions of system states and disasters. Espinoza [21] proposed the points of multi-stage resilience assessment for the first time, and put forward an assessment framework consisting of four phases: threat characterization, vulnerability assessment of the system's components, system's reaction and system's restoration. Panteli [20] innovatively proposed the concept of the multi-phase resilience trapezoid, and quantified the resilience of power systems based on the stages of disturbance process, post-disturbance degraded state and restorative state. Existing resilience assessments, which are usually conducted before disasters, tend to regard the response, adaption and restoration process of power systems as a whole. However, these approaches cannot totally demonstrate the advantages of multi-stage resilience assessment, and the key problems of each stage cannot be revealed thoroughly. To consider the multi-stage characteristics of power system resilience, we divide the resilience assessment into three components: pre-disaster system toughness, during-disaster system resistance and post-disaster system restoration ability. We will define them in detail in Section 2. Furthermore, based on the three stages, assessment algorithms are synthetically proposed. Moreover, the existing metric systems are inadequate and over-simplified to reflect the ability of the power system to withstand destruction of disasters at all stages. A more complete assessment metric system is presented to assess resilience in this paper. The remainder of this paper is structured as follows: Section 2 describes the outline and the necessity of the proposed three-stage power system resilience framework. The resilience assessment methodologies as well as corresponding resilience metrics of pre-disaster, during-disaster and post-disaster stages are discussed respectively. Numerical studies are provided in Section 3 to exhibit the effectiveness and application values of the proposed framework. Finally, the conclusions are drawn in Section 4. Resilience Assessment under a Tri-Stage Framework The Outline of the Tri-Stage Framework In the face of disasters' disturbance, resilient power grids should be robust, to decrease loss of component due to damage and load shedding. They should be able to restore curtailed loads efficiently by operational measures and repair dispatch. Further, in our view, a resilient power system should possess the following characteristics, which are the inspirations of the research. Before disasters, with high-definition meteorological forecast
doi:10.3390/en11061427 fatcat:j3cdmyzoxnglffq6viy2gau6wu