Ryerson University

About: Ryerson University is a education organization based out in Toronto, Ontario, Canada. It is known for research contribution in the topics: Computer science & Population. The organization has 7671 authors who have published 20164 publications receiving 394976 citations. The organization is also known as: Ryerson Polytechnical Institute & Ryerson Institute of Technology.

Control Strategies of Three-Phase Distributed Generation Inverters for Grid Unbalanced Voltage Compensation

Abstract: The high penetration level of power electronics interfaced distributed generation (DG) systems creates great ancillary services potential through the DG interfacing converters, such as the grid unbalanced voltage compensation. However, the unbalanced voltage compensation may cause adverse effects on the DGs' operation, such as output active power oscillation and dc-link voltage variations. Moreover, since the compensation is realized through the available rating of DGs' interfacing converters, it is equally important to consider the effectiveness of control strategy for unbalanced voltage compensation. Considering these challenging issues, two grid unbalanced voltage compensation strategies for three-phase power electronics interfaced DG systems are proposed in this paper. Especially, the first control strategy aims at minimizing the DG's active power oscillation and reducing the adverse effects of unbalanced voltage compensation on DG's operation. The second control strategy focuses on the effectiveness of unbalanced voltage compensation by controlling DG's negative sequence current to be inphase with the grid negative sequence current. Performances of the two proposed control strategies under different grid conditions and DG operating conditions are studied, and recommendations for appropriate control strategy utilization under various conditions are provided. Finally, validity of the proposed strategies is verified by both simulations and experimental results.

Corporate Perspectives on the Development and Use of Sustainability Reports

Abstract: The purpose of this paper is to explore corporate perspectives on the development and use of sustainability reports. Interviews with experts from 35 Canadian corporations were conducted. The research showed that the content of the reports was determined by following standards, conducting an internal evaluation, and other methods. Five corporations were found to develop fully integrated reports, while another 15 included some sustainability aspects in their annual reports. The extent of external stakeholder involvement in the development of the report varied widely, but the majority of the corporations considered stakeholder input. Data collection was handled by a number of different individuals and groups, with sustainability departments often taking a lead role. Twenty-five corporations relied exclusively on internal personnel to write the report, with the remaining corporations using a combination of internal and external writers. A number of key challenges in developing sustainability reports were identified, including timelines, data collection, selecting content, and striking an appropriate balance in reporting. The reports were used internally in a number of different ways, including enhancing employee awareness and engagement and as an internal reference tool. A number of potential future uses of sustainability reports were also mentioned, such as improving the ability to track real-time performance.

High strength blended cement concrete incorporating volcanic ash: performance at high temperatures

Abstract: The strength and durability of high strength blended cement concretes incorporating up to 20% of volcanic ash (VA) subjected to high temperatures up to 800 °C are described The strength was assessed by unstressed residual compressive strength, while durability was investigated by rapid chloride permeability (RCP), mercury intrusion porosimetry (MIP), differential scanning calorimetry (DSC), crack pattern observations and microhardness testing High strength volcanic ash concrete (HSVAC) exhibited better performance showing higher residual strength, chloride resistance and resistance against deterioration at high temperatures compared to the control high strength OPC concrete However, deterioration of both strength and durability of HSVACs increased with the increase of temperature up to 800 °C due to weakened interfacial transition zone (ITZ) between hardened cement paste (hcp) and aggregate and concurrent coarsening of the hcp pore structure The serviceability assessment of HSVACs after a fire should therefore, be based on both strength and durability considerations