Electrical and Computer Engineering Conference Electrical and Computer Engineering Papers, Posters and Presentations 2016 Comparing a transmission planning study of cascading with historical line outage data Ian Dobson Iowa State University, [email protected] M. Papic Idaho Power Company Follow this and additional works at: http://lib.dr.iastate.edu/ece_conf Part of the Power and Energy Commons Recommended Citation Dobson, Ian and Papic, M., "Comparing a transmission planning study of cascading with historical line outage data" (2016). Electrical and Computer Engineering Conference Papers, Posters and Presentations. 48. http://lib.dr.iastate.edu/ece_conf/48 This Conference Proceeding is brought to you for free and open access by the Electrical and Computer Engineering at Iowa State University Digital Repository. It has been accepted for inclusion in Electrical and Computer Engineering Conference Papers, Posters and Presentations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Comparing a transmission planning study of cascading with historical line outage data Abstract The ap per presents an initial comparison of a transmission planning study of cascading outages with a statistical analysis of historical outages. The lp anning study identifies the most vulnerable places in the Idaho system and outages that lead to cascading and interruption of load. This analysis is based on a number of case scenarios (short-term and long-term) that cover different seasonal and operating conditions. The historical analysis processes Idaho outage data and estimates statistics, using the number of transmission line outages as a measure of the extent of cascading. An initial number of lines outaged can lead to a cascading propagation of further outages. How much line outages propagate is estimated from Idaho Power outage data. Also, the paper discusses some similarities in the results and highlights the different assumptions of the two approaches to cascading failure analysis. Keywords Decision support systems, Planning, Power systems Disciplines Electrical and Computer Engineering | Power and Energy Comments This is a manuscript of a proceeding published as Papic, M. and Dobson, I., 2016, October. Comparing a transmission planning study of cascading with historical line outage data. In Probabilistic Methods Applied to Power Systems (PMAPS), 2016 International Conference on (pp. 1-7). IEEE. 10.1109/ PMAPS.2016.7764070. Posted with permission. Rights © 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. This conference proceeding is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/ece_conf/48 Comparing a Transmission Planning Study of Cascading with Historical Line Outage Data M. Papic Ian Dobson Idaho Power Iowa State University Boise, Idaho USA Ames, Iowa USA [email protected] [email protected] Abstract— The paper presents an initial comparison of a Historical assessment of outage data was used for realistic transmission planning study of cascading outages with a identification of outages that likely lead to cascading in the statistical analysis of historical outages. The planning study past [6]-[ll]. identifies the most vulnerable places in the Idaho system and outages that lead to cascading and interruption of load. This Both predictive and historical evaluations of cascading analysis is based on a number of case scenarios (short-term and outages are essential complementary approaches for assessing long-term) that cover different seasonal and operating conditions. The historical analysis processes Idaho outage data and estimates the impacts and risks of cascading outages on system statistics, using the number of transmission line outages as a reliability. However, there has been relatively little attention measure of the extent of cascading. An initial number of lines given to linking these two approaches. outaged can lead to a cascading propagation of further outages. How much line outages propagate is estimated from Idaho Power Historically, there have been a number of blackouts outage data. Also, the paper discusses some similarities in the worldwide that show the vulnerability of the power grid to a results and highlights the different assumptions of the two cascading sequence of events. Considerable efforts have been approaches to cascading failure analysis. put into research and development to identify the causes of these outages and methods to mitigate them [12]-[15]. Keywords—cascading; GATORS; outage data; planning; transmission equipment This paper investigates the outages that lead to cascading in Idaho system by comparing predictive results and results INTRODUCTION obtained from historical outage data. The approach takes into The impact of cascading outages and blackouts on the consideration outages that lead to cascading and those that economy and society is extremely high. The power grid result in load curtailment. Evaluation of historical outages is around the globe today experiences an increased number of based on the Generation and Transmission Outage Reliability cascading outages due to factors such as stress due to System (GATORS) outage database that was started at IPC in increased transfers and unpredictable fluctuations due to 1991 [16]. We also discuss some similarities in the results and increased integration of variable energy sources. highlight the different assumptions of the two approaches to cascading failure analysis. Typical planning and seasonal operating studies, performed by Western Electricity Coordinating Council (WECC) member utilities, use base cases that model the entire Western Interconnection. Idaho Power, since the major blackout event TRANSMISSION PLANNING STUDY OF CASCADING on July 2nd, 1996 that originated in its service territory, continuously evaluates and study its system to ensure that its A. Idaho Power System performance meets not only North Electric Reliability Idaho Power Company service territory covers an area of Corporation (NERC) standards and WECC Reliability Criteria 24,000 square miles serving over 520,000 customers. The [l]-[2] but also going beyond those requirements [3]-[5]. structure of the load is a combination of residential, Idaho Power system is a portion of the Bulk Electric System commercial, and industrial customers coupled with a large (BES) in the Western Interconnection. component of irrigation and air-conditioning loads during the summer. The system is summer peaking, with the all time peak Understanding cascading outages and being able to predict of 3407 MW attained on July 2nd, 2013. The source of most of the associated risks is becoming an integral part of planning IPC's generation is hydroelectric (17 plants), but the company and operation studies by Idaho Power [5], In order to achieve also shares ownership of three coal fired plants. The total the secure operation ofthe system under not just traditional n- installed generating capacity is over 3500 MW with an electric 1 and credible n-2 contingencies but also under other type of power delivery system containing more than 5,800 miles of n-k contingencies with high risks, Idaho Power has developed transmission and 18,000 miles of distribution lines. The bulk a comprehensive risk-based methodology [3]. power system of Idaho is shown in Fig. 1 978-l-5090-1970-0/16/$31.00 ©2016 IEEE PMAPS 2016 quickly identify not just possible initiating events that may lead to cascading outages but also to automatically determine possible cascading chains. A power system network is represented as a number of groups (clusters) that are connected to the network with "critical" lines (cutsets) [12]. In a cluster approach, the system is represented via three types of clusters: load clusters, generation clusters, and connecting clusters. If one of the "critical" lines (e.g., initiating events) within the cluster or connecting two clusters is outaged, it may cause large overloads on other line(s). If an overloaded line(s) is switched off as a system protection measure, this may lead to cascading. Those clusters that experience large flows on the B. Generation and Transmission Outage Reporting System cutset are of a particular interest in this analysis. (GATORS) 3) Tool used Idaho Power's GATORS collects outage data and monitors The cluster-based methodology presented in [12] has been the performance of all generation sources and transmission extended and implemented in the Potential Cascading Modes facilities with an operating voltage of 46 kV and above [16]. (PCM) tool [17]. The PCM tool was used extensively at Idaho Power Company in the past and also to perform study for this In this paper, all transmission lines are categorized and paper. Basic input data to PCM tool are: base case, list of studied by voltage class. The emphasis is placed on the initiating events, monitored constraints (thermal, voltage), analysis of sustained automatic outages of transmission lines. tripping thresholds (line, transformer, load, and generator). The cause codes for sustained outages that are incorporated The most frequent scenarios of cascading outages are that into GATORS are listed in [16]. Each cause-code