Hydro One Limited is an electricity transmission and distribution utility serving the Canadian province of Ontario. Hydro One traces its history to the early 20th century and the establishment of the Hydro-Electric Power Commission of Ontario (renamed "Ontario Hydro" in 1974). In October 1998, the provincial legislature passed the Energy Competition Act which restructured Ontario Hydro into separate entities responsible for electrical generation, transmission/delivery, and price management with a final goal of total privatization.Hydro One was established at this time as a corporation under the Business Corporations Act with the Government of Ontario as sole shareholder. Following its initial public offering on the Toronto Stock Exchange in 2015, the Government of Ontario began selling shares to the public with a final goal of 60% of the company being held by private investors. A report released on 2 December 2015 by the Auditor General of Ontario raised concern with the sale, indicating that power outages are increasing and that Hydro One's equipment is aging and "at very high risk of failing". The estimated cost of necessary repairs was $4.472 billion.
ISRM Symposium - Rock Mechanics: Caverns and Pressure Shafts (International Society for Rock Mechanics). Volume 2: Pressure Tunnels/Tunneling Machines/Underground Storage, Aachen, West Germany
Accurate and reliable passenger demand prediction is crucial for optimizing operations and enhancing the performance of intelligent transportation systems. However, multi-horizon demand forecasting remains challenging as ridership patterns exhibit strong temporal variability and complex spatial interdependencies across routes. Existing forecasting approaches often focus on isolated time series models or short-term horizons, limiting their ability to capture network-wide demand propagation and support proactive operational decision-making. To address these challenges, this study proposes an integrated digital twin framework for public transit built upon the FIWARE ecosystem and next-generation service interfaces-linked data (NGSI-LD) context management standards. The framework consolidates various data sources into a unified, interoperable environment, enabling real-time monitoring and analytics. Within the digital twin, a diffusion convolutional recurrent neural network (DCRNN) is deployed to learn spatio-temporal dependencies and predict passenger demand across multiple horizons (3, 12, and 24 h ahead) for every route in the network. By explicitly capturing spatial correlations between routes that share common stops or segments, the proposed approach captures demand propagation patterns that conventional forecasting methods fail to represent. Experimental results demonstrate that the proposed approach outperforms a standard DCRNN implementation by achieving a lower mean absolute percentage error and explaining up to 94.1% of the variance in passenger demand at the 3hour horizon. Beyond forecasting accuracy, the integration with FIWARE NGSI-LD-based context management enables operational monitoring, proactive alerts, and what-if service scenario analysis within a live operational environment. Overall, this research demonstrates how spatio-temporal graph-based forecasting with digital twin technology can support data-driven decision-making in public transport operations, bridging the gap between predictive analytics and real-world transit management.
Degradation of steam generator (SG) tubing by localized corrosion is a widespread problem in the nuclear industry that can lead to costly forced outages, unit de-rating, SG replacement or even the permanent shutdown of a reactor. In response to the onset of SG tubing degradation at Ontario Hydro's Pickering Nuclear Generating Station (PNGS) Unit 5, and the determined unsuitability of conventional repair methods (mechanically expanded or welded sleeves) for Alloy 400, an alternative repair technology was developed. Electrosleeve is a non-intrusive, low-temperature process that involves the electrodeposition of a nanocrystalline nickel microalloy forming a continuously bonded, structural layer over the internal diameter of the degraded region. This technology is designed to provide a long-term pressure boundary repair, fully restoring the structural integrity of the damaged region to its original state. This paper describes the Electrosleeve process for SG tubing repair and the unique properties of the advanced sleeve material. The successful installation of Electrosleeves that have been in service for more than three years in Alloy 400 SG tubing at the Pickering-5 CANDU unit, the more recent extension of the technology to Alloy 600 and its demonstration in a U.S. pressurized water reactor (PWR), is presented. A number of PWR operators have requested plant operating technical specification changes to permit Electrosleeve SG tube repair. Licensing of the Electrosleeve by the U.S. Nuclear Regulatory Commission (NRC) is expected imminently.
A reliability study has been performed recently at Hydro One to evaluate the reliability of groups of distribution stations involved in a spare transformer sharing policy. The groups may include distribution utilities stations and distribution customer own stations. The study used a probabilistic method based on stationary Markov models and two performance criteria namely the group availability criterion and the total cost criterion in the evaluation. The study results demonstrate that the number of spare transformers required for the groups involved in the spare transformer sharing policy will be reduced while maintaining almost the same reliability levels of individual groups. The purpose of this paper is to describe the study, its reliability assessment method and to illustrate it using a sample system.
This paper presents a survey of real-world subsynchronous oscillation events associated with inverter-based resources (IBR) over the past decade. The focus is on those oscillations in the subsynchronous frequency range known to be influenced by power grid characteristics, e.g., series compensation or low system strength. A brief overview of the historical events is presented followed by detailed descriptions of a series of events. This paper also examines causation mechanisms and proposes future research directions to meet grid needs worldwide.
