This paper is a summary of the IEEE Power System Relaying Committee report. It describes the performance of protective relays during wide-area stressed power system conditions. First, the behavior of protection functions during dynamic operating conditions is described. Then, the lessons learned from studying recent wide area disturbances, as well as the operational history of protection performance during stressed system conditions, are analyzed. Finally, methods of implementing protective relay functions to prevent further propagation of system-wide disturbances are presented.

IEEE PSRC Report on Performance of Relaying During Wide-Area Stressed Conditions

Recent large-scale blackouts in North America, Europe, and other countries raised great concerns over the reliability of our electric energy infrastructure and the economic impacts of blackouts. These blackouts were caused by a cascading sequence of events involving line outages, overloading of other lines, malfunctions of protection systems, power oscillations and voltage problems, and system separation and collapse. In this paper, common characteristics of blackouts are identified by analyzing the cascaded events of the blackouts. It is important to take appropriate control actions to alleviate overload and emergency conditions in a power system in order to avoid catastrophic power outages. This paper discusses available control procedures and emergency control systems needed to help prevent catastrophic outages. Economic losses from these blackouts in the U.S., Europe, and other countries were significant. An evaluation of the economic costs of blackouts can be used to estimate the benefits of emergency control systems that can be installed to prevent blackouts. This paper provides an overview of the assessment methods and procedures for evaluation of the economic costs of blackouts. This paper also describes the generic procedure of an event study to measure the economic impact of blackouts on the values of the firms in financial markets. Copyright © 2008 John Wiley & Sons, Ltd.

Analysis, control, and economic impact assessment of major blackout events

This is a summary for presentation in the panel session, “Understanding, Prediction, Mitigation and Restoration of Cascading Failures” at IEEE PES PSCE 2009. Recent major blackouts in North America, Europe, and other countries highlight the importance of reliability of our electric energy infrastructure and the economic impact of blackouts. These blackouts were caused by a cascading sequence of events including line tripping, overloading of other lines, malfunctions of protection devices, power oscillations and voltage instability, and system splitting and collapse. In this presentation, common characteristics of blackouts are clarified by analyzing the cascaded events of the major blackouts. Appropriate control actions to alleviate emergency conditions including overloads are vital to prevent cascaded events. On the basis of the common characteristics of blackouts, the panelist will discuss available control actions for overloads through system operation and emergency control. The future research needs for mitigating cascaded events will be discussed.

Analysis and control of major blackout events

Power systems in the United States and abroad experienced several wide-area disturbances in the last 15 years including the largest blackout on August 14, 2003, in the Midwest and Northeast U.S. and Ontario, Canada, which impacted millions of customers. On September 28, 2003, the Italian network was separated from the rest of Europe, and the whole country of Italy fell into darkness. The July 2, 1996, and August 10, 1996, major system disturbances in the western U.S. impacted millions of customers. All of these disturbances caused considerable loss of generation and loads and had a tremendous impact on customers and the economy in general. Typically, these disturbances take place when power systems are heavily loaded, are operated outside their intended design limits, and experience multiple outages within a short period of time. These wide-area disturbances are typically characterized by large power oscillations between neighboring utility systems, low network voltages, and consequent voltage or angular instability. The aim of this paper is to explain which relay systems are most prone to operate during stressed system conditions, and why relay systems operate, to share experiences and lessons learned from the past, and to suggest protection system improvements to lessen the impact of blackouts and hopefully lead us toward their prevention in the future

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Relay Performance During Major System Disturbances

This paper was written by a working group of the IEEE power system relay committee to provide guidance to the industry to better coordinate generator protection with generator control. The paper discusses specific calculation methods that can be used to ensure that generator protection and excitation system control are fully coordinated. It also specifically addresses the coordination of relays with generator full load capability and machine steady state stability limits. Because of recent blackouts, NERC (North American electric reliability council) is developing standards for the coordination of generator protection and control. This paper provides practical guidance on providing this coordination.

Coordination of generator protection with generator excitation control and generator capability

Disturbance is an inherent part of any power system during the transition from one steady-state operating condition to the next. Protective relays may experience abnormal operating conditions during this transient period. This paper reviews various control actions that play a part during the transition and provides technical guidance to the industry on the application and setting of generator protective relays that can operate during major system disturbances.

H.J. King

Papers

Performance of Generator protection during major system disturbances