- Email: [email protected]
01901 Application of electrochemical noise analysis to the study of batteries: state-of-charge determination and overcharge detection
06
dummy buses. Injecting appropriate complex power at the break points in the equivalent system preserves the characteristics of the original system. The injected powers are calculated and updated during the iteration process through a reduced order impedance matrix. The performance of the proposed method was investigated on three different test systems with various modifications.
00/01894 A hybrid artificial neural network (ANN) and Ward equivalent approach for on-line power system voltage security assessment Chung. T. S. and Fu. Y. Ekecrric Poner .SI’.\/C,~S Rere~rrc~h. 2000, 53. (3). 165-171. This paper presents a novel hybrid artificial neural network (ANN) and Ward-type equivalent approach for fast, on-line voltage security assessment of power systems. The proposed approach possesses the good properties of Ward equivalent method and can update the parameters of the equivalent model for representing real-time topology change of the external system. Moreover, the boundary equivalent power injection can be quickly matched using hybrid ANN. Test results demonstrate that the new equivalent model is efficient and has accurate response.
00/01895 A hybrid wavelet-Kalman filter method for load forecasting
Zheng, T. E/u. Po~w~ Srst. Rc.~.. 2000. 54. (I ). I I- 17. This paper presents a wavelet transform method for load forecasting. The stochastic nature of the wavelet coefficients for the daily load variation is studied by the decomposition scheme of multiresolution analysis (MRA). The study indicates that the stochastic process of the wavelet coefficients can be modelled as a random walk process. Therefore, the wavelet coefficients are modelled as the state variables of Kalman filters. The best estimation of the wavelet coefficients is obtained by the recursive Kalman filter algorithm. The predicted daily load is the inverse of the predicted wavelet coefficients. Based on the above procedure, two models (weather insensitive and sensitive models) are presented in this paper. Results from an actual system are also presented.
00/01898 A method for measurement and interpretation of impedance spectra for Industrial batteries
Karden, E. J. of Powrr SOIW~ZF. 2000. 85. (I ). 72-78. Impedance spectroscopy is a promising tool for the modelling and diagnosis of industrial batteries. This paper discusses methodological questions connected with the measurement and interpretation of the impedance of such batteries, especially non-linearity, voltage drift, stability. reproducibility, half-cell measurements, model structure and parameter extraction with respect to quantities like state of charge (SOC). On the basis of this discussion, a specialized impedance spectroscope for industrial batteries has been developed, as well as modifications of the standard electrochemical impedance spectroscopy (EIS) algorithm. A mini-cycle technique is suggested that gains additional information compared to classical measurements with continuous dc current offset. Impedance spectra from lead/acid batteries for different dc currents, SOCs. and temperatures are presented and analysed. Reference-electrode measurements allow for separation of the half-cell impedances, Emphasis is placed on the limits of experimental reproducibility due to ‘history’ of the battery.
00/01897 A numerical technique based on symmetrical components for protecting three-winding transformers
Sidhu, T. S. E/w. Powrr Syst. Rrs.. 2000, 54. (I). 19-28. This paper describes a digital technique for protecting three-winding transformers. The technique uses positive- and negative-sequence models of the power system in a fault-detection algorithm. While phase voltages and currents at the transformer terminals are used to detect fault, no information concerning parameters of the transformer and power system is required. The performance of the proposed technique was studied for a variety of operating conditions using data generated hy simulations on an electromagnetic transient programme. The impact of changes in tapsettings, ct ratio-mismatch and saturation of current transformers on the performance of the technique was also studied. Results indicate that the technique is stable during these conditions.
00101898 A robust load flow technique for use in power systems with unified power flow controllers
Fang, W. and Ngan, H. W. E[ec,fric Power S~XIC~I.F Re.worch. 2000, 53. (3). 181-186. This paper proposes a method to calculate the load flow of power systems in which unified power flow controllers (UPFCs) are embedded. Algorithms for deriving the load flow equations including the UPFCs are developed based on an extension of the Newton Raphson load flow (NRLF) technique. By obtaining the sensitivity matrix of the power system including magnitude and phase angle of all bus voltages with respect to parameters of the UPFCs, a practical method of using the UPFC for power flow control is examined. Numerical computation using the proposed technique has been extended to standard IEEE testing bus-systems. It shows that the algorithm is robust, reliable and efficient.
00/01899 Accelerating rate calorimetry studies of the effect of binder type on the thermal stability of a lithiated mesocarbon microbead material in electrolyte Richard,
M. N. and Dahn,
J. R. J. Pmwr
S~mrws.
1999. X3. (l-2).
71-74.
Electrical
power
generation and utilization (scientific, fechnical)
An accelerating rate calorimeter (ARC) is used to measure the thermal behaviour of lithiated MCMB (mesocarbon microhead) electrodes, made with different binder, in electrolyte. Electrodes using PVDF, (VdF:HFP) or (VdF:CTFE) copolymer and ethylenepropy-lene-diene (EPD) terpolymer binders were studied. The safety results for the Vdf-based binder electrodes are almost identical, within error, suggesting that the safety of Li-ion cells is not compromised or improved by changes to the binder within this group. On the other hand, the electrodes made with EPD hinder, that is not plasticized hy the electrolyte, appear to have the lowest self-heating rates.
00/01900 Analysis of a DC motor drive in the presence of unbalance Zhang, J. and Makram, E. B. Ehxrric Powr S~~.srwn Rcveo~clr. 2000. 53, (3). 223-230. The increasing presence of harmonics in power system has caused a need for the development of analytical methods of studying harmonic current effects. This paper describes a new method for modelling a six-pulse DC motor drive. One of the main features is that this model is derived from the actual waveform, which can be more accurate than the traditional constant current source model. Computer simulation method is used to analyse the six-pulse DC motor drive system and to compute the steady state responses of the DC load current and the AC line currents. The currents can he presented as a convenient set of mathematical expressions. The harmonic contents of currents can be obtained using fast Fourier transforms (FFT). In this paper. the effect of unbalanced voltage source is also studied. In addition, a full understanding of the sensitivity of the harmonic currents to different operating conditions is introduced.
00/01901 Application of electrochemical noise analysis to the study of batteries: state-of-charge determination and overcharge detection
Martinet, S. J. Pmwr Sorrrces. 1999. 83, (I-2). 93-99. For the first time, electrochemical noise has been studied for different types of battery under galvanostatic conditions. First, ENA has been applied successfully to sealed Ni-MH batteries: (i) for low capacities, the noise level gives an estimate of the battery state-of-charge. (ii) for high capacities (up to 93 A h), overcharge detection is achieved simultaneously or prior to other known end-of-charge criteria such as voltage and temperature derivatives. Secondly, ENA has been evaluated for overcharge detection of Ni-Cd or Li-ion batteries: (i) similar results to Ni-MH hatteries are obtained for N&Cd technology, (ii) for Li-ion batteries, ENA measurements not only allow overcharge detection but also provide an estimate of the gas evolution rate. This technique could be extended to other batteries producing gas during working or overcharging, such as lead-acid batteries
00/01902 Application of functional modelling to the solution of electrical power system optimization problems
Soukhanov, 0. A. and Shil, S. C. E/c<.. Ponar. S~,.rf Rrs.. 2000. 22. (2). I IY 127. This paper presents theoretical foundations for the application of the principles of functional modelling (FM) to the electrical power systems optimization problems and concrete algorithms for the solution of such of them as optimal operation and optimal development problems. A FM type algorithm includes operations executed on several levels of analysis: lower (subsystem) levels and higher (system) level. On the lower levels functional characteristics of subsystems and their internal variables are calculated, on the higher level boundary variables are computed. Important advantage of FM algorithms is that results obtained with them on each iteration are identical to those of basic sequential algorithms from which they are derived. It is shown in this paper and elsewhere that application of FM algorithms, especially in their parallel realization, can greatly increase effectiveness of optimization problems solution in electrical power systems. Especially efficient is their application to real-time operation control of large power systems.
00/01903 Applications of hydrofluoride ceramic membranes for advanced fuel cell technology Zhu, B. Inr. J. Energ.r Rc.v.. 2000. 24. ( I ). 39-49 New types of materials, hydrofluoride-alumina ceramic composites containing one hydride component, CaHz, have been studied for fuel cell applications. Excellent fuel cell performances were achieved for a peak power density of 180 mW cm-z at 300 mA cm-?, and a short-circuit current density near 1000 mA cm-’ In fuel cell measurements the conductivity and ionic transport properties of the hydrofluoride-based electrolytes have also been investigated. During fuel cell operation. water was often observed at the cathode (air-side), indicating that proton conduction occurs in these electrolyte materials. The experiments show an interesting chance for the future development of innovative fuel cell technology for commercialization.
00101904 Cell testlng by calculated discharge curve method
Djordjevic, A. B. and Karanovic, D. M. ./ Powv Soune.~. 1999. X3. (I 2). 134-140. The actual discharge curve of a primary or secondary cell is a set of measurements: voltage versus time. from which the cell/battery characteristics may be determined as well as the family of calculated discharge curves. In addition to the experimental measured discharge curve. the cell relaxation curve is required. A calculated discharge curve method (CDCM) was developed to improve discharge curve monitoring and cell character-
Fuel and Energy Abstracts
July 2000
213
dummy buses. Injecting appropriate complex power at the break points in the equivalent system preserves the characteristics of the original system. The injected powers are calculated and updated during the iteration process through a reduced order impedance matrix. The performance of the proposed method was investigated on three different test systems with various modifications.
00/01894 A hybrid artificial neural network (ANN) and Ward equivalent approach for on-line power system voltage security assessment Chung. T. S. and Fu. Y. Ekecrric Poner .SI’.\/C,~S Rere~rrc~h. 2000, 53. (3). 165-171. This paper presents a novel hybrid artificial neural network (ANN) and Ward-type equivalent approach for fast, on-line voltage security assessment of power systems. The proposed approach possesses the good properties of Ward equivalent method and can update the parameters of the equivalent model for representing real-time topology change of the external system. Moreover, the boundary equivalent power injection can be quickly matched using hybrid ANN. Test results demonstrate that the new equivalent model is efficient and has accurate response.
00/01895 A hybrid wavelet-Kalman filter method for load forecasting
Zheng, T. E/u. Po~w~ Srst. Rc.~.. 2000. 54. (I ). I I- 17. This paper presents a wavelet transform method for load forecasting. The stochastic nature of the wavelet coefficients for the daily load variation is studied by the decomposition scheme of multiresolution analysis (MRA). The study indicates that the stochastic process of the wavelet coefficients can be modelled as a random walk process. Therefore, the wavelet coefficients are modelled as the state variables of Kalman filters. The best estimation of the wavelet coefficients is obtained by the recursive Kalman filter algorithm. The predicted daily load is the inverse of the predicted wavelet coefficients. Based on the above procedure, two models (weather insensitive and sensitive models) are presented in this paper. Results from an actual system are also presented.
00/01898 A method for measurement and interpretation of impedance spectra for Industrial batteries
Karden, E. J. of Powrr SOIW~ZF. 2000. 85. (I ). 72-78. Impedance spectroscopy is a promising tool for the modelling and diagnosis of industrial batteries. This paper discusses methodological questions connected with the measurement and interpretation of the impedance of such batteries, especially non-linearity, voltage drift, stability. reproducibility, half-cell measurements, model structure and parameter extraction with respect to quantities like state of charge (SOC). On the basis of this discussion, a specialized impedance spectroscope for industrial batteries has been developed, as well as modifications of the standard electrochemical impedance spectroscopy (EIS) algorithm. A mini-cycle technique is suggested that gains additional information compared to classical measurements with continuous dc current offset. Impedance spectra from lead/acid batteries for different dc currents, SOCs. and temperatures are presented and analysed. Reference-electrode measurements allow for separation of the half-cell impedances, Emphasis is placed on the limits of experimental reproducibility due to ‘history’ of the battery.
00/01897 A numerical technique based on symmetrical components for protecting three-winding transformers
Sidhu, T. S. E/w. Powrr Syst. Rrs.. 2000, 54. (I). 19-28. This paper describes a digital technique for protecting three-winding transformers. The technique uses positive- and negative-sequence models of the power system in a fault-detection algorithm. While phase voltages and currents at the transformer terminals are used to detect fault, no information concerning parameters of the transformer and power system is required. The performance of the proposed technique was studied for a variety of operating conditions using data generated hy simulations on an electromagnetic transient programme. The impact of changes in tapsettings, ct ratio-mismatch and saturation of current transformers on the performance of the technique was also studied. Results indicate that the technique is stable during these conditions.
00101898 A robust load flow technique for use in power systems with unified power flow controllers
Fang, W. and Ngan, H. W. E[ec,fric Power S~XIC~I.F Re.worch. 2000, 53. (3). 181-186. This paper proposes a method to calculate the load flow of power systems in which unified power flow controllers (UPFCs) are embedded. Algorithms for deriving the load flow equations including the UPFCs are developed based on an extension of the Newton Raphson load flow (NRLF) technique. By obtaining the sensitivity matrix of the power system including magnitude and phase angle of all bus voltages with respect to parameters of the UPFCs, a practical method of using the UPFC for power flow control is examined. Numerical computation using the proposed technique has been extended to standard IEEE testing bus-systems. It shows that the algorithm is robust, reliable and efficient.
00/01899 Accelerating rate calorimetry studies of the effect of binder type on the thermal stability of a lithiated mesocarbon microbead material in electrolyte Richard,
M. N. and Dahn,
J. R. J. Pmwr
S~mrws.
1999. X3. (l-2).
71-74.
Electrical
power
generation and utilization (scientific, fechnical)
An accelerating rate calorimeter (ARC) is used to measure the thermal behaviour of lithiated MCMB (mesocarbon microhead) electrodes, made with different binder, in electrolyte. Electrodes using PVDF, (VdF:HFP) or (VdF:CTFE) copolymer and ethylenepropy-lene-diene (EPD) terpolymer binders were studied. The safety results for the Vdf-based binder electrodes are almost identical, within error, suggesting that the safety of Li-ion cells is not compromised or improved by changes to the binder within this group. On the other hand, the electrodes made with EPD hinder, that is not plasticized hy the electrolyte, appear to have the lowest self-heating rates.
00/01900 Analysis of a DC motor drive in the presence of unbalance Zhang, J. and Makram, E. B. Ehxrric Powr S~~.srwn Rcveo~clr. 2000. 53, (3). 223-230. The increasing presence of harmonics in power system has caused a need for the development of analytical methods of studying harmonic current effects. This paper describes a new method for modelling a six-pulse DC motor drive. One of the main features is that this model is derived from the actual waveform, which can be more accurate than the traditional constant current source model. Computer simulation method is used to analyse the six-pulse DC motor drive system and to compute the steady state responses of the DC load current and the AC line currents. The currents can he presented as a convenient set of mathematical expressions. The harmonic contents of currents can be obtained using fast Fourier transforms (FFT). In this paper. the effect of unbalanced voltage source is also studied. In addition, a full understanding of the sensitivity of the harmonic currents to different operating conditions is introduced.
00/01901 Application of electrochemical noise analysis to the study of batteries: state-of-charge determination and overcharge detection
Martinet, S. J. Pmwr Sorrrces. 1999. 83, (I-2). 93-99. For the first time, electrochemical noise has been studied for different types of battery under galvanostatic conditions. First, ENA has been applied successfully to sealed Ni-MH batteries: (i) for low capacities, the noise level gives an estimate of the battery state-of-charge. (ii) for high capacities (up to 93 A h), overcharge detection is achieved simultaneously or prior to other known end-of-charge criteria such as voltage and temperature derivatives. Secondly, ENA has been evaluated for overcharge detection of Ni-Cd or Li-ion batteries: (i) similar results to Ni-MH hatteries are obtained for N&Cd technology, (ii) for Li-ion batteries, ENA measurements not only allow overcharge detection but also provide an estimate of the gas evolution rate. This technique could be extended to other batteries producing gas during working or overcharging, such as lead-acid batteries
00/01902 Application of functional modelling to the solution of electrical power system optimization problems
Soukhanov, 0. A. and Shil, S. C. E/c<.. Ponar. S~,.rf Rrs.. 2000. 22. (2). I IY 127. This paper presents theoretical foundations for the application of the principles of functional modelling (FM) to the electrical power systems optimization problems and concrete algorithms for the solution of such of them as optimal operation and optimal development problems. A FM type algorithm includes operations executed on several levels of analysis: lower (subsystem) levels and higher (system) level. On the lower levels functional characteristics of subsystems and their internal variables are calculated, on the higher level boundary variables are computed. Important advantage of FM algorithms is that results obtained with them on each iteration are identical to those of basic sequential algorithms from which they are derived. It is shown in this paper and elsewhere that application of FM algorithms, especially in their parallel realization, can greatly increase effectiveness of optimization problems solution in electrical power systems. Especially efficient is their application to real-time operation control of large power systems.
00/01903 Applications of hydrofluoride ceramic membranes for advanced fuel cell technology Zhu, B. Inr. J. Energ.r Rc.v.. 2000. 24. ( I ). 39-49 New types of materials, hydrofluoride-alumina ceramic composites containing one hydride component, CaHz, have been studied for fuel cell applications. Excellent fuel cell performances were achieved for a peak power density of 180 mW cm-z at 300 mA cm-?, and a short-circuit current density near 1000 mA cm-’ In fuel cell measurements the conductivity and ionic transport properties of the hydrofluoride-based electrolytes have also been investigated. During fuel cell operation. water was often observed at the cathode (air-side), indicating that proton conduction occurs in these electrolyte materials. The experiments show an interesting chance for the future development of innovative fuel cell technology for commercialization.
00101904 Cell testlng by calculated discharge curve method
Djordjevic, A. B. and Karanovic, D. M. ./ Powv Soune.~. 1999. X3. (I 2). 134-140. The actual discharge curve of a primary or secondary cell is a set of measurements: voltage versus time. from which the cell/battery characteristics may be determined as well as the family of calculated discharge curves. In addition to the experimental measured discharge curve. the cell relaxation curve is required. A calculated discharge curve method (CDCM) was developed to improve discharge curve monitoring and cell character-
Fuel and Energy Abstracts
July 2000
213