Power system security enhancement by HVDC links using a closed-loop emergency control

In recent years, guaranteeing that large-scale interconnected systems operate safely, stably and economically has become a major and emergency issue. A number of high profile blackouts caused by cascading outages have focused attention on this issue. Embedded HVDC (High Voltage Direct Current) links within a larger AC power system are known to act as a “firewall” against cascading disturbances and therefore, can effectively contribute in preventing blackouts. A good example is the 2003 blackout in USA and Canada, where the Québec grid was not affected due to its HVDC interconnection. In the literature, many works have studied the impact of HVDC on the power system stability, but very few examples exist in the area of its impact on the system security. This paper presents a control strategy for HVDC systems to increase their contribution to system security. A real-time closed-loop control scheme is used to modulate the DC power of HVDC links to alleviate AC system overloads and improve system security. Simulations carried out on a simplified model of the Hydro-Québec network show that the proposed method works well and can greatly improve system security during emergency situations.Peer reviewedFinal Accepted Versio

Energy policies and risks on energy markets; a cost-benefit analysis

The key question dealt with in this report is whether and how governments should be involved in taking measures regarding security of energy supply. In order to answer this question, we developed a framework for cost-benefit analysis and applied this framework to a number of policy options. Read also the press release and accompanying�document ' Increasing the reliability of electricity production: a cost-benefit analysis '. The options chosen vary from government investments in strategic oil stocks to financial incentives for consumers to reduce their consumption of electricity. The set of options comprises several types of governmental action, including subsidies, regulation and government investments. Moreover, the selection includes measures meant to address risks on all three major energy markets: oil, natural gas, and electricity. The general picture following from the cases studied is that security of supply measures are hardly ever beneficial to welfare: benefits of policy measures do generally not outweigh costs. From an economic point of view, therefore, it would be often wiser to accept consequences of supply disruptions than to pursue security of supply at any cost. This implies that governments should exercise caution in imposing measures regarding security of supply. If serious market failure is detected, careful attention should be paid to the design of the corrective measure. Establishing and maintaining well-functioning markets appears to be an efficient approach in realising a secure supply of energy. That approach would include removal of entry barriers, securing equal access to essential facilities and increasing transparency of markets.

Competition Without Chaos

California heralded the New Year with a wave of rolling blackouts, spiraling wholesale electricity prices, and at least one utility bankruptcy. California, which symbolizes the electronic age and represents an eighth of the U.S. economy and its population, faces electricity supply issues not seen since the Great Depression and the collapse of the great utility holding companies. To what extent is California the bellwether for the restructured electric industry in the United States? We do not believe that the recent crisis in California is a signal that competition and deregulation have failed. Indeed, it remains our firm belief that market-oriented restructuring of the electric industry remains the best opportunity to provide consumer benefits and to develop reliable new sources of supply. After all, a major impetus for introducing competition into the generation and marketing of electricity has been the previous failures in long-term planning decisions made by public utilities and their regulators. The regulated monopoly regime simply did not provide the correct economic incentives for a company to provide electric service efficiently. To what extent can other states that have restructured their electric industries expect to see California-like dramatic sustained price increases and supply shortages resulting in rolling blackouts? The root cause of California's problems was its long-term failure to build generating plants during the most sustained economic boom in the state's history. California's most significant restructuring problem was also a local issue. The California restructuring law required utilities collecting stranded costs to retain fixed price obligations to retail customers, while preventing them from hedging their price risk in the wholesale market by entering into long-term supply contracts. The California market design flaws have been avoided in the restructuring legislation enacted by the twenty-four states and the District of Columbia that have restructured electricity markets. Among these states are Pennsylvania and Illinois, the states where Exelon conducts public utility businesses. The restructuring efforts in these other states are generally yielding results quite different from those in California and demonstrate that thoughtful, market-oriented, evolutionary restructuring can work well for all parties. This is not a reason, however, for complacency. Government agencies, utilities and all market stakeholders must work hard to make sure this answer remains valid a few years hence. This work includes establishing appropriate pricing and incentives to encourage the building of new supply and the development of demand-side management programs; establishing regional transmission organizations in order to support the expansion of and appropriate pricing for transmission; establishing appropriate rules and pricing regarding the utilities provider of last resort or default supply obligation. The default supply issue is one of the most significant challenges to the transition to competition. If the delivery companies retain primary responsibility for arranging supply and thus lock up most of the generation sources, the result is reliable service and stable rates for customers. However, new market entrants' access to supply sources will be limited and at high prices, making it difficult for them to compete. To resolve this dilemma, we propose a bifurcated approach to default service offerings and pricing. For large customers, who have the most desirable service characteristics to competitive suppliers and thus more opportunity to hedge their price risk, the utilities' only default service obligation would be unbundled energy at a market price. For mass market customers, who lack hedging ability because of limited, if any, market development, the utilities would provide a fixed price, multi-year energy supply offering. The price for both offerings must include a risk premium adequate to compensate the utility for the risk it assumes and to avoid rates that are too low to allow alternative suppliers to compete. We believe our default supply resolution will achieve the competing goals of price stability, reliability, and the development of a mature competitive market. The California experience is not an accident or the product of bad luck. It is the product of choices, long-term choices about siting generation and transmission, and the more recent choice of a market design that imposed asymmetric risks on utilities to the ultimate detriment of all. If other states make similar choices, similar consequences can be expected to follow. In short, the California experience is no reason to reject restructuring; it is rather a forceful lesson on the importance of doing it right.

Impact Assessment of Hypothesized Cyberattacks on Interconnected Bulk Power Systems

The first-ever Ukraine cyberattack on power grid has proven its devastation by hacking into their critical cyber assets. With administrative privileges accessing substation networks/local control centers, one intelligent way of coordinated cyberattacks is to execute a series of disruptive switching executions on multiple substations using compromised supervisory control and data acquisition (SCADA) systems. These actions can cause significant impacts to an interconnected power grid. Unlike the previous power blackouts, such high-impact initiating events can aggravate operating conditions, initiating instability that may lead to system-wide cascading failure. A systemic evaluation of "nightmare" scenarios is highly desirable for asset owners to manage and prioritize the maintenance and investment in protecting their cyberinfrastructure. This survey paper is a conceptual expansion of real-time monitoring, anomaly detection, impact analyses, and mitigation (RAIM) framework that emphasizes on the resulting impacts, both on steady-state and dynamic aspects of power system stability. Hypothetically, we associate the combinatorial analyses of steady state on substations/components outages and dynamics of the sequential switching orders as part of the permutation. The expanded framework includes (1) critical/noncritical combination verification, (2) cascade confirmation, and (3) combination re-evaluation. This paper ends with a discussion of the open issues for metrics and future design pertaining the impact quantification of cyber-related contingencies

Microgrids: Legal and Regulatory Hurdles for a More Resilient Energy Infrastructure

Natural disasters and climate change have made it apparent that energy infrastructure needs to be modernized and microgrids are one type of technology that can help the electricity grid become more resilient, reliable, and efficient. Different states have begun developing microgrid pilot projects including California, New York, Connecticut, and Pennsylvania. The City of Pittsburgh, Pennsylvania is the first city to propose implementing “energy districts” of microgrids that will serve as critical infrastructure, in the first phase, and then expand to commercial and community settings. This large project involves many shareholders including public utilities, government agencies, and private entities. Utilizing microgrids on such a large scale raises issues regarding its classification, as energy generation or energy storage, and whether it should be regulated by public utilities, private entities, or municipalities. In a state like Pennsylvania where the energy market has been deregulated, there is strong concern on what the public utilities involvement will be with microgrid projects. This Note focuses on the regulatory issues that are raised with the construction and operation of microgrids at such a large scale in Pittsburgh. It addresses the difficulties that arise when implementing microgrids in a deregulated energy market state such as Pennsylvania, where little to no statutory language exists regarding microgrids. It will give an overview of proposed Pennsylvania legislation that may impact a public utilities’ control over microgrid technology and the benefits and costs when examining the extent of the public utilities’ role regarding ownership and control of microgrids in a deregulated energy market

Benchmarking and Validation of Cascading Failure Analysis Tools

Cascading failure in electric power systems is a complicated problem for which a variety of models, software tools, and analytical tools have been proposed but are difficult to verify. Benchmarking and validation are necessary to understand how closely a particular modeling method corresponds to reality, what engineering conclusions may be drawn from a particular tool, and what improvements need to be made to the tool in order to reach valid conclusions. The community needs to develop the test cases tailored to cascading that are central to practical benchmarking and validation. In this paper, the IEEE PES working group on cascading failure reviews and synthesizes how benchmarking and validation can be done for cascading failure analysis, summarizes and reviews the cascading test cases that are available to the international community, and makes recommendations for improving the state of the art

Application of Game Theory to Improve the Defense of the Smart Grid

This thesis presents the development and evaluation of a distributed agent based system using reputation based trust and game theoretic techniques to improve the defense of the future smart grid from cyber-attack and equipment malfunctions. Future smart grid capabilities promise to leverage network technologies to revolutionize the production, transmission, distribution and consumption of electrical power. However, the internet like communication also increase the power grid\u27s vulnerability to cyber-attack. This thesis uses simulation linking power systems with communication networks to demonstrate the benefits of a Distributed Decision Making Communication Enable Special Protection System (SPS) using reputation based trust and game theory to protect the power grid from malicious and non-malicious malfunctions. The simulations show that a distributed approach to SPS load shedding successfully maintains power grid stability after an electrical disturbance while using reputation based trust to defend the load shedding from cyber-attack and equipment malfunction. Additional simulations demonstrate the application of game theory to defend the SPS load shedding process when available resources prevent the monitoring and defense of every part of the power grid. The demonstrated capability increases the resiliency of the power grid by preventing uncontrolled blackouts through detection and mitigation of attacks, improving the system\u27s reliability

Modeling Cascading Failures in Power Systems in the Presence of Uncertain Wind Generation

One of the biggest threats to the power systems as critical infrastructures is large-scale blackouts resulting from cascading failures (CF) in the grid. The ongoing shift in energy portfolio due to ever-increasing penetration of renewable energy sources (RES) may drive the electric grid closer to its operational limits and introduce a large amount of uncertainty coming from their stochastic nature. One worrisome change is the increase in CFs. The CF simulation models in the literature do not allow consideration of RES penetration in studying the grid vulnerability. In this dissertation, we have developed tools and models to evaluate the impact of RE penetration on grid vulnerability to CF. We modeled uncertainty injected from different sources by analyzing actual high-resolution data from North American utilities. Next, we proposed two CF simulation models based on simplified DC power flow and full AC power flow to investigate system behavior under different operating conditions. Simulations show a dramatic improvement in the line flow uncertainty estimation based on the proposed model compared to the simplified DC OPF model. Furthermore, realistic assumptions on the integration of RE resources have been made to enhance our simulation technique. The proposed model is benchmarked against the historical blackout data and widely used models in the literature showing similar statistical patterns of blackout size