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Register a new userPower Off! Challenges in Planning and Executing Power Isolations on Shared-Use Electrified Railways
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Electric railways are fast, clean, and safe, but complex to operate and maintain. Electric traction infrastructure includes signal power and feeder lines that remain live during isolations and complicate maintenance processes. Stakeholders involved in power outage planning include contractors, linemen, groundmen, power directors, dispatchers, conductor-flag, and support personnel. Weekly planning processes for track time requires many contingencies due to large number of moving parts and factors not known in advance, like personnel availability. Electrical and mechanical environments faced by crews working in adjacent areas may be entirely different and require a bespoke circuit configuration to de-energize catenary, which must be planned meticulously. Although recent automation improved real-time plate order communications between power directors and dispatchers, each outage still requires many manual switching operations. Net impact of this isolation process reduces available construction work windows nightly from a nominal 7 hours to 2 hrs 39 mins. We recommend joint design of electrical and civil infrastructure, cross-training between disciplines, limiting maximum number of concurrent outages, formal study of maintenance outage capacity, and further automation in power switching.
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Motivated by FERCs recent direction and ever-growing interest in cloud adoption by power utilities, a Task Force was established to assist power system practitioners with secure, reliable and cost-effective adoption of cloud technology to meet various business needs. This paper summarizes the business drivers, challenges, guidance, and best practices for cloud adoption in power systems from the Task Forces perspective, after extensive review and deliberation by its members that include grid operators, utility companies, software vendors and cloud providers. The paper begins by enumerating various business drivers for cloud adoption in the power industry. It follows with the discussion of challenges and risks of migrating power grid utility workloads to cloud. Next for each corresponding challenge or risk, the paper provides appropriate guidance. Importantly, the guidance is directed toward power industry professionals who are considering cloud solutions and are yet hesitant about the practical execution. Finally, to tie all the sections together, the paper documents various real-world use cases of cloud technology in the power system domain, which both the power industry practitioners and software vendors can look forward to design and select their own future cloud solutions. We hope that the information in this paper will serve as useful guidance for the development of NERC guidelines and standards relevant to cloud adoption in the industry.
Accurate inertia estimates and forecasts are crucial to support the system operation in future low-inertia power systems. A large literature on inertia estimation methods is available. This paper aims to provide an overview and classification of inertia estimation methods. The classification considers the time horizon the methods are applicable to, i.e., offline post mortem, online real time and forecasting methods, and the scope of the inertia estimation, e.g., system-wide, regional, generation, demand, individual resource. Shortcomings of the existing inertia estimation methods have been identified and suggestions for future work have been made.
Repurposing automotive batteries to second-use battery energy storage systems (2-BESS) may have environmental and economic benefits. The challenge with second-use batteries is the uncertainty and diversity of the expected packs in terms of their chemistry, capacity and remaining useful life. This paper introduces a new strategy to optimize 2-BESS performance despite the diversity or heterogeneity of individual batteries while reducing the cost of power conversion. In this paper, the statistical distribution of the power heterogeneity in the supply of batteries is considered when optimizing the choice of power converters and designing the power flow within the battery energy storage system (BESS) to maximize battery utilization. By leveraging a new lite-sparse hierarchical partial power processing (LS-HiPPP) approach, we show a hierarchy in partial power processing (PPP) partitions power converters to a) significantly reduce converter ratings, b) process less power to achieve high system efficiency with lower cost (lower efficiency) converters, and c) take advantage of economies of scale by requiring only a minimal number of sets of identical converters. The results demonstrate that LS-HiPPP architectures offer the best tradeoff between battery utilization and converter cost and had higher system efficiency than conventional partial power processing (C-PPP) in all cases.
We present an omnidirectional wireless power transfer (WPT) system capable of automatic power flow control using three orthogonal transmitter (Tx)-repeater (Rp) pairs. The power drawn from each transmitter is automatically adjusted depending on the mutual inductance between the receiver and the Tx-Rp pair. The proposed approach enables the receiver to harvest almost uniform power with high efficiency (90%) regardless of its position.
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Maddumage Karunaratne
, Christopher Gabany (Department of Electricaln Engineering
, University of Pittsburgh
2019
This experiment demonstrates to engineering students that control system and power system theory are not orthogonal, but highly interrelated. It introduces a real-world power system problem to enhance time domain State Space Modelling (SSM) skills of students. It also shows how power quality is affected with real-world scenarios. Power system was modeled in State Space by following its circuit topology in a bottom-up fashion. At two different time instances of the power generator sinusoidal wave, the transmission line was switched on. Fourier transform was used to analyze resulting line currents. It validated the harmonic components, as expected, from power system theory. Students understood the effects of switching transients at various times on supply voltage sinusoid within control theory and learned time domain analysis. They were surveyed to gauge their perception of the project. Results from a before/after assessment analyzed using T-Tests showed a statistically significant enhanced learning in SSM.
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