An Assessment of PIER Electric Grid Research 2003-2014 White Paper

This white paper describes the circumstances in California around the turn of the 21st century that led the California Energy Commission (CEC) to direct additional Public Interest Energy Research funds to address critical electric grid issues, especially those arising from integrating high penetrations of variable renewable generation with the electric grid. It contains an assessment of the beneficial science and technology advances of the resultant portfolio of electric grid research projects administered under the direction of the CEC by a competitively selected contractor, the University of California’s California Institute for Energy and the Environment, from 2003-2014

Operating strategies to preserve the adequacy of power systems circuit breakers

The objective of the proposed research is to quantify the limits of overstressed and aging circuit breakers in terms of probability of failure and to provide guidelines to determine network reconfigurations, generator commitment, and economic dispatch strategies that account for these limits. The proposed temporary power system operating strategies address circuit breaker adequacy issues and allow overstressed breakers to be operated longer and more reliably until they are replaced with adequate equipment. The expansion of electric networks with new power sources (nuclear plants, distributed generation) results in increased short-circuit or fault currents levels. As fault currents increase, they will eventually exceed circuit breaker ratings. Circuit breakers exposed to fault currents in excess of their ratings are said to be overstressed, underrated, or inadequate. Insufficient ratings expose overstressed breakers to increased failure probabilities. Extensive common-mode outages caused by circuit breaker failures reduce the reliability of power systems. To durably avoid outages and system unreliability, overstressed breakers must eventually be replaced. Large-scale replacements of overstressed breakers cannot be completed in a short time because of budgetary limits, capital improvement schedules, and manufacturer-imposed constraints. Meanwhile, to preserve the ability of old and overstressed breakers to safely interrupt faults, short-circuit currents must be kept within the limits imposed by the ratings and the age of these breakers by using the substation reconfiguration and generator commitment strategies described in this study. The immediate benefit of the above-mentioned operating strategies is a reduction of the failure probability of overstressed breakers obtained by avoiding the interruption of currents in excess of breaker ratings. Other benefits include (i) increased network reliability, (ii) restored operating margins with respect to existing equipment, and (iii) prioritized equipment upgrades that enhance the long-term planning of power systems.Ph.D.Committee Chair: Meliopoulos, A. P. Sakis; Committee Member: Divan, Deepakraj M.; Committee Member: Harley, Ronald G.; Committee Member: Johnson, Ellis L.; Committee Member: Taylor, David G

Portuguese transmission grid incidents risk assessment

Documento confidencial. Não pode ser disponibilizado para consultaTese de doutoramento. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 201

Electrical Grid Resilience in Critical Infrastructure

The constant growth in world population and the constant technological advances, which lead to new equipment and solutions that become indispensable in the daily life of human beings, created a considerable increase in electricity's consumption. It is, therefore, essential to use this resource as efficiently as possible and in a way that reaches everyone safely. The need for resilient infrastructures is now emerging so that there is the ability to ensure their normal functioning after an adverse phenomenon so that the infrastructures and systems we depend on are not compromised. This problem applies to infrastructures that provide essential services on a day-to-day basis to the society, such as in this specific case study, a Data Center. In these cases, proper functioning is essential in times of crisis to technology companies and other entities that provide services to other companies or the average user. Following this problem arises the theme of this dissertation, whose implementation was carried out in a business context. A methodology is then proposed to quantify and evaluate the impact that an equipment's failure had on a given infrastructure, taking into consideration its im-portance and the time taken to resolve it, in a simple and easy to understand manner. This would be useful for all those who in the future need to recur to a detailed historical data, of critical and non-critical events, of this infrastructure. To obtain a quantitative value, a metric that considers the technical characteristics of the analyzed infrastructure will be used. These companies need to remain competitive with their target audience so that they can thrive in today's market. It is essential that they can understand how to deal with a failure in an equipment or component without neglecting the economic side since all decisions made thereafter should aim to return to the pre-event state as quickly as possible. There is, therefore, a need to understand the impact that a failure can have on an infrastructure to act accordingly to its severity. In the carried-out tests, it was concluded that the system provided values that allowed to order the events that occurred over a year according to their real impact and the simulations per-formed on randomly selected components were as intended

Risk-based security assessment for operating electric power systems

The power system is a widespread and complex network whose complete behavior, at present, still remains partially characterized. Power systems have operated in most cases reliably, but conservatively with the help of many deterministic techniques that rely heavily on the modeling of system components and the associated dynamics. Now, with increasing competition and growing demand, the power system, however, has been shifting from a deterministically regulated system to a competitive and uncertain market environment. Power utilities are required to have a comprehensive knowledge of the risks as well as benefits in their transmission operations. Our interest is motivated by this need of the industry to provide a method to quantify the risk of operating a power system with consideration to the probabilistic nature of system behaviors. The objective of this dissertation is to develop a foundation of risk-based bulk power system security assessment that leads to the definition, calculation, and application of the risk in operating electric power systems. The work includes three parts of risk assessments: transmission line thermal overload, voltage insecurity, and composite risk assessments. Both the probability of insecurity problems and their cost consequences are measured such that an expected monetary impact is given as the measurement of risk. This quantitative measurement of thermal, voltage, and composite risk is helpful for the operator to trade off the benefits and costs in the competitive utility environment. For making this economic tradeoff, several decision criteria, including both deterministic and probabilistic strategies, from conservative to greedy preference, are introduced to aid the operator to make operating decisions. This research establishes a bridge between power system security and economics by the index of risk that is compatible with the economic results of market-based electricity trading. Both the method to quantify the risk and the ways to apply it in decision-making make contributions to the power industry

Renewable Electric Energy Integration: Quantifying the Value of Design of Markets for International Transmission Capacity

Integrating large quantities of supply-driven renewable electricity generation remains a political and operational challenge. One of the main obstacles in Europe to installing at least 200 GWs of power from variable renewable sources is how to deal with the insufficient network capacity and the congestion that will result from new flow patterns. We model the current methodology for controlling congestion at international borders and compare its results, under varying penetrations of wind power, with a model that simulates an integrated European network that utilises nodal/localised marginal pricing. The nodal pricing simulations illustrate that congestion - and price - patterns vary considerably between wind scenarios and within countries, and that a nodal price regime could make fuller use of existing EU network capacity, introducing substantial operational cost savings and reducing marginal power prices in the majority of European countries.Power market design, renewable power integration, congestion management, transmission economics

On the identification and analysis of ICT-induced stability risks in cyber-physical energy systems

This thesis addresses emerging ICT-based stability risks for cyber-physical energy systems (CPESs) in light of the increasingly complex task of coordinating modern generation and consumption assets in power grids. It does so by identifying cyber-physical services as the main drivers of interdependence first. It then provides a general approach on how to assess such a service's dependence on data in general and its sensitivity towards the high-level ICT error categories "latency", "data loss" and "data corruption" in particular. Based on these results, the service states "normal", "limited", and "failed" are introduced in order to summarise the findings in an abstract and more widely applicable as well as comparable manner. These aggregated service states are required as additional inputs for the main method which determines how disturbances propagate through modern CPESs. This method is first presented with a focus on static stability and is later extended to also incorporate dynamic stability phenomena. The resulting disturbance propagation, combined with the service states and the ENTSO-E state description for power systems, can be used to derive a summarising state trajectory which helps compare different CPES layouts and control designs concerning their stability.Diese Arbeit befasst sich mit neuartigen, IKT-basierten Stabilitätsrisiken für cyber-physikalische Energiesysteme (CPES) vor dem Hintergrund zunehmend komplexer Koordination neuartiger Verbraucher und Erzeugungsanlagen in modernen Energiesystemen. Dazu werden zunächst IKT-basierte Dienste als Haupttreiber wechselseitiger Abhängigkeiten zwischen der Energie- und IKT-Domäne im CPES identifiziert. Anschließend wird ein Ansatz zur Bewertung der Datenabhängigkeit solcher Dienste im Allgemeinen sowie ihrer Empfindlichkeit gegenüber erhöhter Kommunikationslatenz, Datenverlust und Datenkorruption im Speziellen vorgestellt. Basierend auf diesen Ergebnisse werden drei Betriebszustände für Dienste eingeführt. Diese lauten "normal", "eingeschränkt" und "fehlerhaft" und dienen der Abstraktion und Vergleichbarkeit der IKT-Abhängigkeit verschiedener Dienste. Im Anschluss wird eine Methode vorgestellt, die der Bestimmung der Ausbreitung von Störungen innerhalb des CPES dient. Die Methode wird zunächst mit einem Fokus auf statischer Stabilität erläutert und anschließend so erweitert, dass auch dynamische Stabilitätsphänomene berücksichtigt werden können. Die sich daraus ergebende Ausbreitung von Störungen kann in Verbindung mit den Betriebszuständen und der ENTSO-E-Zustandsbeschreibung für Stromversorgungssysteme zur Ableitung eines zusammenfassenden Zustandsverlaufs verwendet werden. Mit den so ermittelten Zustandsverläufen wird wiederum ein qualitativer Stabilitätsvergleich verschiedener CPES-Layouts und Regelungskonzepte ermöglicht