Showing papers by "Hydro-Québec published in 1986"

Phase Diagrams and Conductivity Characterization of Some PEO ‐ LiX Electrolytes

Abstract: systems have been characterized by x‐ray diffraction and optical microscopy, and the resulting phase diagrams are taken into account for the interpretation of ac impedance measurements. Eutectic reactions and multiple‐intermediate‐compound formation are characteristic of most systems. Simple phenomenological models do not explain the overall conductivity behavior. The activation energy of ion transport is independent of the anion, and remains mainly constant at 0.7 eV over the concentration range studied for . Ion‐pair formation seems to occur at low salt concentration.

A Monte-Carlo Simulation Method for the Economic Assessment of the Contribution of Wind Energy to Power Systems

Abstract: A method for determining the costeffectiveness of wind energy and the economic limitations of penetration into electrical power systems is presented. It is based on a Monte-Carlo approach which simulates the hour-by-hour operation of the power system. The hourly random variations in wind and load are modeled in addition to the operating constraints inherent in conventional generation. The economic assessment is based on a selected one-year simulation period, Two examples of the application of this method are given.

Alarm system and method for detecting proximity of an object to electrical power lines

Abstract: An antenna receives, by capacitive effect, a current of which the intensity is a function of the distance separating the antenna from an electrical power line. The other factors that influence the current are fixed, constant or are considered negligible. A measuring and conditioning circuit converts the current at the output of the antenna into a coded signal and transmits this coded signal to a control unit. The control unit compares the coded signal to predetermined values stored therein. Alarms are generated by the control unit when the current from the antenna exceeds the predetermined values.

Propagation and Elimination of Torque Ripple in a Wind Energy Conversion System

Abstract: The 2P and 4P harmonics of the torque supplied by a two blade vertical axis wind turbine (WT) propagates in the drive train of the wind turbine and deteriorates the quality of the electric power transmitted to the network. This paper shows how the torque ripple propagates and how it can be eliminated by electrical instead of mechanical means. This elimination is obtained by using a converter-fed synchronous generator and by adopting suitable control strategies.

Velocity-space structure of runaway electrons

Abstract: The region of velocity space is determined in which electron runaway occurs because of a dc electric field. Phase‐space analysis of the relaxation equations describing test electrons, corroborated by two‐dimensional (2‐D) numerical integration of the Fokker–Planck equation, reveals that the Dreicer condition for runaway v2∥≥(2+Zi)Ec/E is only sufficient. A weaker condition v2∥≥(2+Zi)1/2Ec/E is established, and it is shown, in general, that runaway in velocity space only occurs for those electrons that are outside one of the separatrices of the relaxation equations. The scaling with v∥ of the parallel distribution function and of the perpendicular temperature is also derived.

A Synthesis Method for One-Port and Multi-Port Equivalent Networks for Analysis of Power System Transients

Abstract: Equivalent networks can be used in power system simulation to reduce simulation equipment or computer time and memory space. In this paper, an iterative method is developed for synthesizing one-port equivalent networks by the removal of poles corresponding to resonances of the driving-point impedance or admittance function. This results in networks formed by the series or parallel connection of modular RLC circuits. The RLC values are calculated using a parameter-optimization technique. Multi-port equivalent networks are first configured as ? or T forme composed of one-port network branches and the latters are then synthesized by the proposed method for one-port equivalent networks.

Effect of Contact Aid Compounds on the Performance of Bolted Aluminum-to-Aluminum Joints Under Current Cycling Conditions

Abstract: A number of contact aid compounds most commonly used for aluminum-to-aluminum connectors and conductors were evaluated on the basis of their effect on the performance and stability of a bolted joint under current cycling conditions. The results show that a significant difference exists in the effect that some of the contact aids exert on the performance of the bolted joints under current cycling conditions. This difference manifests itself in higher contact resistance and rapid overheating of a joint during cycling. The observed difference was associated with the shear strength of the compound film and also with the properties of the additives such as metallic particles present in these compounds.

A local-circulation model for Darrieus vertical-axis wind turbines

Abstract: A new computational model for the aerodynamics of the vertical-axis wind turbine is presented. Based on the local-circulation method generalized for curved blades, combined with a wake model for the vertical-axis wind turbine, it differs markedly from current models based on variations in the streamtube momentum and vortex models using the lifting-line theory. A computer code has been developed to calculate the loads and performance of the Darrieus vertical-axis wind turbine. The results show good agreement with experimental data and compare well with other methods. 12 references.

Silicone oil as replacement fluid for PCBs in transformers

Abstract: A brief critical review of the electrical, thermal and flammability properties of silicone oil for transformers is presented in comparison to the same properties for polychlorinated biphenyl fluids (PCB) and mineral oil It is deduced that silicone oil is an acceptable substitute for PCBs Despite a significantly lower fire resistance, silicone oil is not toxic and is compatible with traces of PCBs and mineral oil It is therefore perfectly suited for the retrofilling of PCB contaminated transformers

The hydrogen evolution reaction on Ni-Sn alloys and intermetallics

Abstract: Ni-Sn alloys containing 0%, 1.1%, 11.6%, 25.5%, 40.3%, 63.5%, 77.9%, 83.5%, 98% and 100% tin were prepared and examined regarding their activity towards the hydrogen evolution reaction in sulphuric acid solutions. The composition of these alloys and intermetallics was determined from the initial weight of the constituents used in the alloy preparation. The identification of various phases was carried out by X-ray diffraction analysis using ASTM standard microfiles. The surface composition of these alloys was determined by Auger electron spectroscopy for several typical cases, both before and after the cathodic polarization. The electrochemical measurements consisted of steady state potentiostatic polarization curves at various temperatures and potentiodynamic profiles. The electrochemical data deduced include Tafel slopes, exchange current densities, apparent heats of activation and potentiodynamic behaviour. On nickel and nickel-rich intermetallics, electrochemical desorption is indicated as the rate-determining step whereas the hydrogen evolution reaction appears to proceed by the initial dischange mechanism on tin and tin-rich alloys. Also the activity of nickel-rich intermetallics approaches that of nickel whereas the tin-rich alloys tend to exhibit activity similar to that of tin.

Method and device for controlling the erosion of the electrodes of a plasma torch

Abstract: Method and device for controlling the erosion of the electrodes of a plasma torch, in which an electrical arc is produced when the electrodes are connected to an electrical supply. An axial magnetic field generated by a system of field coil causes the rotation of the extremities of the arc according to a circular trajectory inside the electrodes. The relative position of the field coils is such that there exists a position on the electrode surface where the value of the total magnetic field is a minimum where the arc runs thereby controlling the erosion of the electrodes. According to the invention, the value of current is periodically varied in the system of field coil used to cause the rotation of the arc, thereby producing a controlled axial displacement of the circular trajectory of the extremity of the arc. The plasma torch according to the invention is characterized by structure to periodically vary the value of the current in the field coil system used to cause the rotation of the arc thereby producing a controlled axial displacement of the circular trajectory of the extremity of the arc. Under these conditions, the life of the electrodes is substantially increased.

Pressure Relief Design and Performance of Metal Oxide Surge Arresters

Abstract: Surge arresters with porcelain housing must not have explosive breakage of the housing to minimize damage to other equipment when subjected to internal high short circuit currents. Also, arrester porcelain housings are generally susceptible to undesirable thermal shock. As a solution, this paper describes pressure relief design and performance of arresters equipped with a fiber reinforced plastic tube and an optimum pressure relief nozzle. The arresters showed satisfactory performance during a newly developed synthetic pressure relief test using a 25 kA symmetrical rms current with the first half-cycle fully offset.

Apparatus for detecting defective insulators in an insulating column supporting an electrical conductor in a power circuit line

Abstract: A method and apparatus for detecting defective insulators in an insulating column supporting an electrical conductor in a power line. The column is made of a plurality of serially connected insulator members. Voltage present on the conductor supported by the column generates an electric field about it. The presence of faulty insulators within the column causes field redistribution and discontinuities in it. A specially configured electric field probe is provided to measure at predetermined distance and locations, this electric field. A displacement device is provided whereby to displace the probe along an axis substantially parallel along the length of the column to automatically obtain measurements. Means to analyze the measurements are provided and allow to identify the defective insulators whose positions correspond to the locations of the discontinuities in the electric field surrounding the column. The main advantage of this method is that no electrical contact need to be made to the insulators.

Austenitic stainless steel with high cavitation erosion resistance

Abstract: An austenitic stainless steel alloy showing a high cavitation erosion resistance making it particularly useful for the manufacture and/or repair of hydraulic machine components. The alloy consists essentially of from 8 to 30% by weight of Co; from 13 to 30% by weight of Cr; from 0.03 to 2.0% by weight of C; up to 0.3% by weight of N; up to 5.0% by weight of Si; up to 1.0% by weight of Ni; up to 2.0% by weight of Mo; and up to 16% by weight of Mn, the balance being substantially Fe, with the proviso that at least one of the following conditions is satisfied: the amount of C is higher than 0.3%, and/or the amount of Si is higher than 3.0% and/or the amount of Mn is higher than 9.0%. Moreover, the amounts of the above mentioned elements that are respectively known as ferrite formers (Cr, Mo, Si) and as austenite former (C, N, Co, Ni, Mn) and amongst said austenite and ferrite formers, the amount of each of these elements that are respectively known to increase and lower the stacking fault energy, are respectively selected and balanced so that at least 60% by weight of the alloy is, at ambient temperature, in a face centered cubic phase having a stacking fault energy low enough to show a fine deformation twinning under cavitation exposure or, alternatively, to make this face centered cubic phase transformable under cavitation exposure to a hexagonal close pack e-phase and/or a α-martensitic phase showing such a fine deformation twinning.

Universal apparatus for detecting faults in microprocessor systems

Abstract: A universal apparatus for the detection of faults in microprocessor systems. Microprocessors are commonly commercialized under the form of integrated circuits having a plurality of pins. The apparatus thus comprises a connector provided with pins so positioned that they can be inserted in the connection device of the microprocessor of a faulty system, in the place of the pins of this microprocessor after the same has been withdrawn. An interface defines for each pin of the connector a line having a programmable direction. A programmed controller associated with a memory which stores a copy of the software of the faulty system is connected to the interface for (a) programming the direction of the lines in order to simulate the interconnections which are normally established between the system and its microprocessor, and (b) carrying out tests on this system through the simulated interconnections for detecting the fault. The controller can of course be programmed to detect faults in a plurality of different microprocessor systems. The memory associated therewith then stores a copy of the software of all these systems.

Perspectives in Electrochemical Physics

Abstract: There are many areas of chemistry that draw heavily upon and interact strongly with the corresponding advances in physics and which, together, are called chemical physics. The more common examples of these areas are quantum chemistry, statistical thermodynamics, and the myriad forms of spectroscopy, etc. Similarly, there is one prominent field of physics, namely, solid-state physics, which has a profound influence on the development and progress of electrochemistry. The research endeavor on electrochemical problems which depend heavily upon the notions of solid-state physics for their proper elucidation is best grouped under electrochemical physics, in analogy with the chemical physics mentioned above.

Image Reconstruction Techniques For Computed Tomography From Sparse Data: X-Ray Imaging On The Varennes Tokamak And Other Applications.

Abstract: Computer assisted tomography will be used on the Varennes tokamak, a medium size thermonuclear fusion research device, to reconstruct 2-D images of the X-ray emission from the plasma Five full views or projections of the plasma with 16 detectors each will be available with a temporal resolution of a few microseconds The X-ray imaging system and the reconstruction technique must take advantage of any prior knowledge of the object or plasma since the viewing access is quite limited and the data available is sparse Comparative simulated examples demonstrate the advantages of Fourier harmonic expansion reconstructions over two other popular techniques An example of possible industrial applications involving gross detection of material defects and local density variations is also discussed

Ultraviolet spectrophotometric determination of gadolinium in concentrated solutions of nitrate salts

Abstract: Ultraviolet spectroscopy was successfully applied for determining the gadolinium concentration in Gd(NO/sub 3/)/sub 3/ solutions. The /sup 6/I/sub 15/2/, /sup 6/I/sub 13/2/ reverse arrow /sup 8/S/sub 7/2/ transitions of the Gd/sup 3 +/ ion, which are responsible for the fine structure at 272.8 nm, were selected as a basis for the investigation of three analytical modes, one based on three wavelength measurements (mode ABS) and the others on first- and second-derivative measurements (modes deltaA/deltalambda and delta/sup 2/A/deltalambda/sup 2/). For the particular problem concerned here, namely, to deal with nitrate interference in the spectral region of interest (270-280 nm), the best performance was shown by the first-order derivative mode, which had a precision of +- 0.035 g L/sup -1/, a discrimination limit of 0.071 g L/sup -1/, and an accuracy of 0.60% for an 8 g L/sup -1/ Gd solution. This study shows that it is possible to adopt this principle for quantitative analysis of the Gd(NO/sub 3/)/sub 3/ solutions (0.0509 M or 8 g L/sup -1/ Gd) used in the emergency shutdown systems of CANDU-PHW (Canada deuterium uranium-pressurized heavy water) reactors. 19 references, 4 figures, 2 tables.

Motion of an electron bunch through a plasma

Abstract: In space research, pulse-modulated beams, or bunches, of energetic electrons have been used for tracing magnetic field lines and for remote sounding of magnetospheric electric fields Doubts have been expressed regarding the possibility that an electron bunch would be able to travel through the plasma in space However, experiments in the ionosphere have shown that, at least on some occasions, bunches of electrons with energies of a few keV have traveled over long distances with no apparent energy loss The present study is concerned with the theoretical explanation for this phenomenon The method employed in this study makes use of a direct numerical integration of the Vlasov equation The results obtained provide the basis for a provisional conclusion concerning the stability of a moving electron bunch in the considered case It appears that the system is mildly unstable

Development-Scheme Selection for River Valleys

Abstract: This paper presents a new approach to the problem of selecting a development scheme for a river valley from preliminary surveys on candidate sites. Rather than proceeding by elimination, this approach identifies the scheme which minimizes the investment and operating costs. This minimization problem is decomposed using the Benders technique into a master problem covering the site selection and sizing aspects and a subproblem covering the production aspect. The former is solved by mixed-integer linear programming whereas the latter is transformed by a Lagrangian relaxation into a nonlinear network flow problem which is solved by a variant of the Frank-Wolfe method. Numerical results are reported.

Influence of Water and Silanol Contents on Some Electrical Properties of Silicone Oil

Abstract: The precise measurement of water in silicone oils is difficult owing to the reaction of water with siloxane to give silanols. In this paper we report kinetic and equilibrium measurements of the water and silanol content in 50 cSt silicone oils from different manufacturers. Using various techniques, we show that the water content in silicone oil varies linearly with relative humidity. The silanol content was deduced and is never less than 80 to 150 ppm in dry oil; it increases nonlinearly with RH. The influence of water and silanols on several electrical properties of silicone oil is also discussed.

A Multimicroprocessor-Based Controller for a Static Frequency Changer

Abstract: This paper describes a static frequency changer controller in which the triggering pulse production as well as the various regulator algorithms have been implemented by the use of a multimicroprocessor system. The system includes a microprocessor-based triggering pulse generator designed for a three-phase converter supplied by a variable-frequency ac input. A complete description of this pulse generator is presented, and experimental results obtained with the static frequency changer are shown.

Relations between expansivity, compressibility and density of polyethylene

Abstract: From a compilation of 17 different data sources on the expansivity and compressibility of polyethylene (PE) it is shown that these parameters are linearly related to the density (measured at 22°C) of the polymer. Since the correlations cover a wide range of density (0.9 to ∼1 g/cm3) and temperature (100 to 395 K), it is hoped that they may apply to all polyethylenes. The relationship between the thermal coefficient of pressure and density of PE as a function of temperature is also presented.

Dynamic performance of digital recorders used for monitoring high-voltage impulse tests

Abstract: Frequency- and time-domain characteristics of digital transient recorders (in short, digitizers) are discussed in order to establish the requirements on digitizers used for high-voltage testing. Results of an experimental study performed on a 200-MHz 8-bit digitizer are presented and related to the design features of this instrument. The inherent design characteristics and their influence on the digitizer dynamic performance are analyzed in view of simulation of the digitizer through a computer model.