Showing papers by "Hydro-Québec published in 1998"

Electrochemistry of Anodes in Solid‐State Li‐Ion Polymer Batteries

Abstract: An examination of the electrochemical performance of solid-state lithium-ion batteries was carried out using a solvent-free solid-polymer electrolyte at 60°C. We studied two different types of anode (negative electrode) material: graphite intercalation compound (GIC) or lithium-titanium oxide (Li 4 Ti 5 O 12 ), and LiCoO 2 was used as the cathode (positive electrode). Natural graphite and carbon fiber gave high reversible capacities of about 372 and 300 mAh/g, respectively. A Li 4 Ti 5 O 12 vs. lithium cell discharged at the C/15 rate delivered 155 mAh/g corresponding to a 97% first-cycle Coulombic efficiency. The irreversible capacity was high when carbon material was used as the negative electrode. However, this sacrificial capacity was very small when we replaced carbon with the spinel material. The crystallographic structure of Li 4 Ti 5 O 12 was analyzed by X-ray diffraction, and its stability was demonstrated by in situ scanning electron microscopy using Li 4 Ti 5 O 12 , which is a zero-strain insertion material that offers advantages for the solid-polymer electrolyte cell including safety, long life, and reliability.

Equalizer system and method for series connected energy storing devices

Abstract: An apparatus and method for regulating the charge voltage of a number of electrochemical cells connected in series are disclosed. Equalization circuitry is provided to control the amount of charge current supplied to individual electrochemical cells included within the series string of electrochemical cells without interrupting the flow of charge current through the series string. The equalization circuitry balances the potential of each of the electrochemical cells to within a predetermined voltage setpoint tolerance during charging, and, if necessary, prior to initiating charging. Equalization of cell potentials may be effected toward the end of a charge cycle or throughout the charge cycle. Overcharge protection is also provided for each of the electrochemical cells coupled to the series connection. During a discharge mode of operation in accordance with one embodiment, the equalization circuitry is substantially non-conductive with respect to the flow of discharge current from the series string of electrochemical cells. In accordance with another embodiment, equalization of the series string of cells is effected during a discharge cycle.

Bypass apparatus and method for series connected energy storage devices

Abstract: A bypass apparatus and method for series connected energy storage devices. Each of the energy storage devices coupled to a common series connection has an associated bypass unit connected thereto in parallel. A current bypass unit includes a sensor which is coupled in parallel with an associated energy storage device or cell and senses an energy parameter indicative of an energy state of the cell, such as cell voltage. A bypass switch is coupled in parallel with the energy storage cell and operable between a non-activated state and an activated state. The bypass switch, when in the non-activated state, is substantially non-conductive with respect to current passing through the energy storage cell and, when in the activated state, provides a bypass current path for passing current to the series connection so as to bypass the associated cell. A controller controls activation of the bypass switch in response to the voltage of the cell deviating from a pre-established voltage setpoint. The controller may be included within the bypass unit or be disposed on a control platform external to the bypass unit. The bypass switch may, when activated, establish a permanent or a temporary bypass current path.

Thermal management system and method for a solid-state energy storing device

Abstract: An improved electrochemical energy storing device includes a number of thin-film electrochemical cells which are maintained in a state of compression through use of an internal or an external pressure apparatus. A thermal conductor, which is connected to at least one of the positive or negative contacts of each electrochemical cell, conducts current into and out of the electrochemical cells and also conducts thermal energy between the electrochemical cells and thermally conductive material disposed on a wall structure adjacent the conductors. The wall structure includes electrically resistive material, such as an anodized coating or a thin film of plastic. The thermal conductors are fabricated to include a spring mechanism which expands and contacts to maintain mechanical contact between the electrochemical cells and the thermally conductive material in the presence of relative movement between the electrochemical cells and the wall structure. An active cooling apparatus may be employed external to a hermetically sealed housing containing the electrochemical cells to enhance the transfer of thermal energy into and out of the electrochemical cells. An integrated interconnect board may be disposed within the housing onto which a number of electrical and electro-mechanical components are mounted. Heat generated by the components is conducted from the interconnect board to the housing using the thermal conductors.

Experience with the detection of faulty composite insulators on high-voltage power lines by the electric field measurement method

Abstract: Hydro-Quebec's experience with polymer insulators began in 1977. A sixteen km section of a 735 kV transmission line near Quebec City was then re-insulated with 282 composite insulators of three different makes in equal proportions. The objective was to study them under real service conditions in order to evaluate their performance and to assess the relative merits of each make. This experimentation was later extended to some other lines and/or voltage levels and has continued up to now. During all these years, various methods of testing composite insulators in-service have been experimented with and early in the 1990s, the first device developed at IREQ for the in-situ testing of porcelain insulators by the electric field method was modified and adapted for use on composite suspension insulators. This paper presents a few cases of insulators having a particularly dangerous type of failure mode and found on the lines by the use of the electric field method. Some background information on the detection of defects by this method is also given and some of the experiments done in the laboratory on composite insulators to define the limits of the method are described.

Fault-tolerant battery system employing intra-battery network architecture

Abstract: A distributed battery system includes a number of energy storing modules, each of which includes a processor and communications interface. In a network mode of operation, a battery computer communicates with each of the module processors over an intra-battery network and cooperates with individual module processors to coordinate module monitoring and control operations. The battery computer monitors a number of battery and module conditions, including the potential and current state of the battery and individual modules, and the conditions of the battery's thermal management system. A module transitions to a stand-alone mode of operation if the module detects an absence of communication connectivity with the battery computer. The module processor autonomously coordinates monitoring of current, potential, and temperature conditions, effects bypassing of defective cells, equalizes cell voltages during charge and discharge cycles, and detects and logs fault conditions arising in the module.

Conforming and non-conforming current for attributing steady state power quality problems

Abstract: RMS fluctuations, waveform distortion and three-phase unbalance are some of the major aspects of power quality for which many measuring instruments exist today. This paper presents a concept for sharing the responsibility for these deteriorations between the electric utility and their customers. The sharing is based solely on measurements during power system operation.

Mercury Accumulation and Biomagnification in Ospreys (Pandion haliaetus) in the James Bay and Hudson Bay Regions of Québec

Abstract: Mercury exposure was examined in adults and nestlings of ospreys (Pandion haliaetus) from lakes, rivers, and hydroelectric reservoirs in northern Quebec between 1989 and 1991 by assessing the amount of mercury transferred from fish to ospreys, which are voracious fish-eaters. The high mercury concentrations detected in adult feathers and tissues (feathers, blood, liver, kidneys, muscles, brain) of nestlings indicate an increase in mercury availability at recently constructed hydroelectric reservoirs (10–12 years for the La Grande-2 Reservoir). With mean total mercury levels of 37.3 mg/kg and 1.9 mg/kg in feathers (dry weight) and in blood (wet weight), respectively, contamination rates were, in both tissues, five times higher for chicks born near the La Grande Reservoirs (western sector) than in those reared in natural habitats. Furthermore, the mean quantity of total mercury in 40-day-old chicks reared near a reservoir was 10.5 mg, compared with to 1.6 mg for those reared in a natural environment.

Solid-state energy storage module employing integrated interconnect board

Abstract: The present invention is directed to an improved electrochemical energy storage device. The electrochemical energy storage device includes a number of solid-state, thin-film electrochemical cells which are selectively interconnected in series or parallel through use of an integrated interconnect board. The interconnect board is typically disposed within a sealed housing which also houses the electrochemical cells, and includes a first contact and a second contact respectively coupled to first and second power terminals of the energy storage device. The interconnect board advantageously provides for selective series or parallel connectivity with the electrochemical cells, irrespective of electrochemical cell position within the housing. In one embodiment, a sheet of conductive material is processed by employing a known milling, stamping, or chemical etching technique to include a connection pattern which provides for flexible and selective interconnecting of individual electrochemical cells within the housing, which may be a hermetically sealed housing. Fuses and various electrical and electro-mechanical devices, such as bypass, equalization, and communication devices for example, may also be mounted to the interconnect board and selectively connected to the electrochemical cells.

Ultra thin solid state lithium batteries and process of preparing same

Abstract: There is provided a mother-battery containing at least the following films: an anode of metallic lithium or sodium, a polymer electrolyte which is conductive towards the alkaline ions of the anode and also acts as a separator between the electrodes, and a composite cathode consisting of a compound which is reducible to lithium or sodium, an additive of electronic conduction and a polymer electrolyte binder. The mother battery also includes an electronically conductive thin coating on the external face of the anode and, possibly of the cathode, in which the conductive material is chemically inert towards the electrode material and which also serves to establish permanent electrical contacts on the external faces. The laminated mother-battery of larger surface area and at least partially charged is thereafter subjected to a sharp mechanical cutting out to give thin polymer electrolyte batteries with lithium or sodium anode. The thus cut out batteries preserve substantially their voltage after mechanical cutting out which is recovered by a mechanism of self-healing.

Simultaneous ultrawide and narrowband detection of PD pulses in dielectric liquids

Abstract: Simultaneous narrow band (300 kHz) and wide band (500 MHz) measurements were carried out to obtain estimates of the apparent charge transfer associated with discrete isolated discharge pulses and discharge pulse bursts, which are observed to occur in dielectric liquids when wide band detection systems are utilized. The integrated apparent charge transfers determined with the narrow band system ranged from 12 to 95 pC, which represents typically the lower range of values normally encountered with PD activity in dielectric liquid-filled or impregnated equipment. While the discharge phenomena in perfluoro polyether liquids was found to be typified by sporadic appearances of single isolated pulses involving charge transfers between 33 and 38 pC, the discharge events in mineral oils assumed most frequently the form of pulse bursts, displaying the usual pulse sequences of quasi-ascending amplitudes; the overall integrated apparent charge transfer of the observed pulse bursts extended commonly from 12 to 16 pC. The charge release, occurring with the first (initiating) smallest discharge pulse within the pulse bursts, was estimated to be of the order of /spl sim/1 pC.

Electrolytic composition with polymer base for electrochemical generator

Abstract: The invention concerns an aprotic electrolytic composition located in the separator and in at least one composite electrode containing a powder of an active electrode material, and if necessary an electronic conduction additive of an electrochemical generator. The electrolytic composition comprises a first polymer matrix consisting of a polyether and at least a second polymer matrix, macroscopically separated, and also at least an alkaline salt as well as a polar aprotic solvent: The polymer matrices are capable of being swollen by at least one of the polar aprotic solvents. The solvent or mixture of solvents is unevenly distributed between the polymer matrices. The invention also concerns an electrochemical generator comprising a negative electrode and positive electrode reversible to alkaline ions and a separator with polymer electrolyte, the electrolytic component of which is the composition described above. The invention further concerns the manufacture in two or three steps of a sub-assembly of an electrochemical generator by coating an electrode support with a composite electrode containing the second matrix, followed by a surface coating on the electrode resulting from the preceding step with a solution containing the first polymer matrix so as to form the separator wholly or partly.

A link between EMTP and MATLAB for user-defined modeling

Abstract: This paper presents a programmed link between MATLAB and EMTP (Electromagnetic Transients Program). It is an interconnection where MATLAB functions can be called in from the EMTP Fortran code. The interconnection provides a user-defined modeling tool where the high-level computation facilities of MATLAB and its powerful Toolboxes can be advantageously used in the general network simulator context of the EMTP.

Multi-loop power system stabilizers using wide-area synchronous phasor measurements

Abstract: A distributed-measurement technology using the Global Positioning System and accurate phasor measurements units is expected to become the most powerful source of wide-area dynamic information. This paper explores ways of putting this extended real-time knowledge of the power system behavior into use, by means of supplementary feedback loops which improve dynamic and transient system stability and, ultimately, increase the transmission capacity. The control design is based on a 2-stage methodology of which first step is built on a powerful pulse-response-based numerical subspace state-space identification algorithm to identify a reduced-order, small-signal MIMO model of the open-loop system. The second step is to select an appropriate control structure and then tune the stabilizer parameters accordingly. To tackle the most difficult situations, the architecture selected comprises several dynamic feedback loops, each consisting of a high-order differential filter. Controller tuning is then performed by minimizing a selective modal performance index in the parameter space, Adding stability and robustness constraints greatly improves the engineering significance of the resulting design. For illustration, we provide a full design of a three-loop stabilizer for a major synchronous-condenser station an actual power system which simultaneously uses two global and one local input signals. Both linear and nonlinear simulation results clearly demonstrate the added value of wide-area information when properly included in power system stabilizer design.

Lithium-polymer type battery and control system

Abstract: A battery controller system for a metal and solid electrolyte battery, such as a lithium-polymer battery has temperature sensors arranged to detect a temperature of cells in the battery, heating elements arranged to heat the cells, a heating element controller receiving signals from the temperature sensors and controlling a current supplied to the heating elements so as to maintain each one of the cells at a predetermined temperature, and a power mode controller detecting a demand for power from the battery and setting the predetermined temperature in response to a level of power to be supplied from or to the battery. The power mode controller sets at least a floating temperature, a charging temperature, and a power supply temperature. The controller also has voltage sensor detecting a voltage of each one of the cells during use, and determines whether any one of the cells is susceptible to damage by continued use. The battery is disconnected from the power connection in response to determination that one of the cells may be damaged.

Varistors based on nanocrystalline powders produced by mechanical grinding

Abstract: The invention concerns novel varistors based on zinc oxide and a method for making same, which consists in using as base products nanocrystalline powders obtained by high-intensity mechanical grinding and in subjecting the mixture resulting from said nanocrystalline powders a consolidating treatment such as sintering, in suitably selected temperature and time conditions so as to retain the smallest possible grain size of ZnO. The resulting varistors have a very fine homogeneous microstructure and an average grain size characteristically not more than 3 νm, i.e. five times smaller than standard materials. Said novel varistors have a larger number of grain boundaries per length unit and therefore a much higher breakdown voltage. Said voltage is characteristically higher than 10 kV/cm and can reach 17 kV/cm which is almost one order of magnitude above the breakdown voltage of standard varistors. The non-linearity coefficient of the current-voltage curve is also improved, and is greater than 20 and can reach values as high as 60. Moreover, the leakage currents below the breakdown voltage of said varistors, are much weaker.

Streamer propagation and breakdown under ac voltage in very large oil gaps

Abstract: This paper presents a study of prebreakdown and breakdown phenomena under ac voltage in mineral oil in very large gaps (/spl les/80 cm). The investigations presented concern the measurement of breakdown voltages together with the recording of streamers in rod-plane and sphere-plane electrode systems, at different gap sizes. A breakdown mode specific to ac voltage is found, in which 'bursts' composed of streamers initiated at each half cycle appear. This mode leads to the lowest breakdown fields recorded under ac. Values of the average stress required for burst or direct breakdown modes are deduced from the experiments. Positive streamers are responsible for breakdown in large gaps: their propagation is easy and does not depend on the gap geometry and on the presence of particles. On the other hand, the propagation of negative streamers is quenched when not very divergent fields are used.

Apparatus and method for evaluation a condition of a magnetic circuit of an electric machine

Abstract: The method consists in positioning a probe in front of a pair of teeth provided on the face of the magnetic circuit of an electric machine. The probe has spaced apart magnetic prong portions having respective end faces adapted to match the teeth of the pair with the end faces in registry with the teeth. The prong portions are respectively provided with an excitation winding and a measurement winding. The excitation winding is excited to induce a magnetic flux in a test zone formed of the teeth in front of the probe and a portion of the magnetic circuit extending therebetween. The current flowing in the excitation winding and the voltage across the measurement winding are measured for calculating a resulting power which is indicative of the condition of the test zone. The apparatus is formed of the probe and electronics carrying out the above functions.

Dynamic and non-contact measurement of displacement or of permittivity by use of a capacitive sensor

Abstract: A method for dynamic and non-contact measurement of the displacement of a conductive substance with respect to a capacitive sensor formed by two parallel conductive plates, superimposed, electrically insulated from one another, and fed by a high frequency signal having a predetermined voltage, the capacitive sensor being connected to a device for detecting a current value. Also disclosed is a method for dynamic and non-contact measurement of the permittivity of a dielectric substance between a conductive part and a capacitive sensor of the above-mentioned type.

Progesterone concentrations during estrous cycle of dairy cows exposed to electric and magnetic fields.

Abstract: Sixteen multiparous nonpregnant lactating Holstein cows (each weighing 662 ± 65 kg in 150.4 ±40 day of lactation) were confined to wooden metabolic cages with 12:12 h light:dark cycle during the experiment. The cows were divided into two sequences of eight cows each and exposed to electric and magnetic fields (EMF) in an exposure chamber. This chamber produced a vertical electric field of 10 kV/m and a uniform horizontal magnetic field of 30 μT at 60 Hz. One sequence was exposed for three estrous cycles of 24 to 27 days. During the first estrous cycle, the electric and magnetic fields were off; during the second estrous cycle, they were on; and during the third estrous cycle, they were off. The second sequence was also exposed for three 24 to 26 days estrous cycles, but the exposure to the fields was reversed (first estrous cycle, on; second estrous cycle, off; third estrous cycle, on). The length of each exposure period (21 to 27 days) varied according to the estrous cycle length. No differences were detected in plasma progesterone concentrations and area under the progesterone curve during estrous cycles between EMF nonexposed and exposed periods (2.28 ±0.17 and 2.25 ± 0.17; and 24.5 ± 1.9 vs. 26.4 ± 1.9 ng/ml, respectively). However, estrous cycle length, determined by the presence of a functional corpus luteum detected by concentrations of progesterone equal to or more than 1 ng/ml plasma, was shorter in nonexposed cows than when they were exposed to EMF (22.0 ± 0.9 vs. 25.3 ± 1.4 days). Bioelectromagnetics 19:438–443, 1998. © 1998 Wiley-Liss, Inc.

Modified lithium vanadium oxide electrode materials, products, and methods

Abstract: A method of improving certain vanadium oxide formulations is presented. The method concerns fluorine doping formulations having a nominal formula of LiV3O8. Preferred average formulations are provided wherein the average oxidation state of the vanadium is at least 4.6. Herein preferred fluorine doped vanadium oxide materials, electrodes using such materials, and batteries including at least one electrode therein comprising such materials are provided.