155,737 research outputs found
Multiobjective optimization for pricing system security in electricity markets
No full text(© 2003 IEEE) Milano, F., Canizares, C. A., & Invernizzi, M. (2003). Multiobjective optimization for Pricing System security in electricity markets. IEEE Transactions on Power Systems, 18(2), 596–604. https://doi.org/10.1109/tpwrs.2003.810897This paper proposes a novel technique for representing system security in the operations of decentralized electricity markets, with special emphasis on voltage stability. An interior point method is used to solve the optimal power flow problem with a multiobjective function for maximizing both social benefit and the distance to maximum loading conditions. A six-bus system with both supply and demand-side bidding is used to illustrate the proposed technique for both elastic and inelastic demand, and a 129-bus test system that models the Italian HV transmission network is used for testing the practical applicability of the proposed method. The results obtained show that the proposed technique is able to improve system security while yielding better market conditions through increased transaction levels and improved locational marginal prices throughout the system
Voltage stability constrained OPF market models considering N-1 contingency criteria
No full textThis paper proposes two novel techniques for including contingencies in OPF-based electricity market computations and for the estimation
of a “system-wide” available transfer capability (SATC). The OPF problem formulation includes voltage stability constraints and a loading
parameter in order to ensure a proper stability margin for the market solution. Two methods are proposed. The first technique is an iterative
approach and computes an SATC value based on an N − 1 contingency criterion for an initial optimal operating condition, to then solve an
OPF problem for the worst contingency case; this process is repeated until the changes in the SATC values are below a minimum threshold.
The second approach solves a reduced number of OPF problems associated with contingency cases according to a ranking based on a power
transfer sensitivity analysis of the transmission lines. Both methods are tested on a 6-bus system and on a realistic 129-bus Italian network
model considering supply and demand side bidding. Local marginal prices and nodal congestion prices resulting from the proposed solutions
as well as comparisons with results obtained by means of a standard OPF technique are also presented and discussed
Correction: Developing consensus outcome measures in juvenile systemic sclerosis: a global survey of pediatric rheumatologists and literature review (Pediatric Rheumatology, (2025), 23, 1, (46), 10.1186/s12969-025-01100-8)
No full textFollowing publication of the original article [1], we have been notified that the tagging of the first author’s last name was incorrect and should be Vasquez-Canizares instead of Canizares. Additionally, the authorship list should include the mention: “for the CARRA Juvenile Scleroderma Workgroup” and the following sentence be added to the Acknowledgments section: “The authors wish to acknowledge CARRA and the ongoing Arthritis Foundation financial support of CARRA.” The original article has been corrected
On bifurcations, voltage collapse and load modeling
No full text(© 1995 IEEE) Canizares, C. A. (1995). On bifurcations, voltage collapse and load modeling. IEEE Transactions on Power Systems, 10(1), 512–522. https://doi.org/10.1109/59.373978This paper discusses the relation between bifurcations and power systems stability through a thorough analysis of several examples, to clarify some ideas regarding the usefulness and limitations of bifurcation theory in network studies and operation, particularly in voltage stability related issues. Different types of load models are used in a sample system to analyze their effect on system stability and bifurcation. Finally, the Ecuadorian National Interconnected System is used to depict and discuss the effect of load modeling in saddle-node bifurcation analysis of real power systems
A vector energy function approach for security analysis of AC/DC systems
No full text(© 1992 IEEE) DeMarco, C. L., & Canizares, C. A. (1992). A vector energy function approach for security analysis of AC/DC Systems. IEEE Transactions on Power Systems, 7(3), 1001–1011. https://doi.org/10.1109/59.207313The authors examine dynamic behavior in system models that reflect reasonably detailed third-order high-voltage DC (HVDC) dynamics along with AC system models that include reactive flows, and frequency and voltage-dependent load models. A vector Lyapunov function approach is used to define a system-wide energy function that can be used for general security analysis. They describe the derivation of individual component Lyapunov functions for simplified models of HVDC links connected to infinitely strong AC systems, along with a standard AC only system Lyapunov function. A novel method of obtaining weighting coefficients to sum these components for the overall system energy function is proposed. Use of the new energy function for transient stability and security analysis was illustrated in a test system
Time dependence of controls to avoid voltage collapse
No full text(© 2000 IEEE) Vargas, L. S., & Canizares, C. A. (2000). Time dependence of controls to avoid voltage collapse. IEEE Transactions on Power Systems, 15(4), 1367–1375. https://doi.org/10.1109/59.898114In this paper, the effect of time dependence of control actions used to avoid voltage collapse, such as reactive power compensation and load shedding, is studied. A thorough justification of the phenomena under study is first presented with the help of a simple test system. The time dependence of the control actions is then studied in a real voltage collapse scenario of the Chilean Interconnected System (CIS), based on a reduced system model
The Operation of Ontario's Competitive Electricity Market: Overview, Experiences, and Lessons
No full text(© 2007 IEEE) Zareipour, Hamidreza, Canizares, C. A., & Bhattacharya, K. (2007). The operation of Ontario’s Competitive Electricity Market: Overview, experiences, and lessons. IEEE Transactions on Power Systems, 22(4), 1782–1793. https://doi.org/10.1109/tpwrs.2007.907979Competitive electricity markets have been operating in various countries for more than a decade, with every single electricity market presenting its own unique characteristics and features. This paper provides a comprehensive overview of the operational aspects of the Ontario electricity market, its unique features, and its outcomes for the first four years of operation. Several programs implemented in the Ontario market to improve efficiency, transparency, and competitiveness are analyzed, and the effectiveness of these programs are discussed
Photoelectrocatalytic Oxidation of Methyl Orange on a TiO2 Nanotubular Anode Using a Flow Cell
No full textMethyl orange from water was removed by photocatalytic anodic oxidation using a titanium dioxide array surface. The coating was prepared by anodizing a titanium plate in an ethylene glycol electrolyte-containing NH4F followed by heat treatment to realize a photocatalytic surface under UV light. Scanning electron microscopy imaging showed that the array coating consisted of closely spaced nanotubes perpendicular to the titanium plate. The aqueous solution of methyl orange was circulated through a rectangular channel flow cell containing the coated anode. The effects of electrolyte flow rate and applied potential on the oxidation rate and efficiency were evaluated. At higher mean linear flow rates, the efficiency of the oxidation process improved, indicating a mass transport-controlled process. At more positive applied potentials, the TiO2 structure deteriorated resulting in a lower oxidation efficiency
A high intensity, high stability 3.5 MV SingletronTM accelerator
No full textHigh Voltage Engineering has developed a high-current, light-ion 3.5 MV single-ended accelerator system to meet the stringent requirements on beam intensity and stability of the LUNA-MV project at Laboratori Nazionali del Gran Sasso (LNGS), L'Aquila, Italy. The accelerator has an all permanent magnet, 10 GHz ECR ion source to deliver intense beams of H (∼1 mA), He and C. The machine ensures energy stability below 10−5, terminal voltage ripple of 1.5 × 10−5 and uninterrupted operations time greater than 24 h as requested by LNGS. Various changes to the standard in-line Singletron accelerator were needed to satisfy these requirements. In this paper, we highlight design details about the accelerator and ECR source and present early performance results. © 2018 Elsevier B.V
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