{"title":"A method to determine closest Hopf bifurcation in power systems considering exciter and load dynamics","authors":"C. P. Gupta, R. K. Varma, S. Srivastava","doi":"10.1109/EMPD.1998.705541","DOIUrl":"https://doi.org/10.1109/EMPD.1998.705541","url":null,"abstract":"Saddle-node and Hopf bifurcations have been recognized as the reasons behind power system voltage instability. In general, Hopf bifurcation is found to occur well before the saddle-node bifurcation under system parameter variation. This paper presents a method to determine the closest Hopf bifurcation from the given operating point considering generator, exciter and load dynamics. The closest distance has been computed in load parameter space using an optimization based model. Results obtained on a sample power system network reveals that the stability margin computed with respect to the Hopf bifurcation further shrinks when load dynamics is considered.","PeriodicalId":434526,"journal":{"name":"Proceedings of EMPD '98. 1998 International Conference on Energy Management and Power Delivery (Cat. No.98EX137)","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122489012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Reliable electrical power supply by DGS for unbundled power quality services","authors":"K. Nara, Y. Hayashi","doi":"10.1109/EMPD.1998.705400","DOIUrl":"https://doi.org/10.1109/EMPD.1998.705400","url":null,"abstract":"The authors propose a new electrical power delivery system named FRIENDS (Flexible, Reliable and Intelligent Electrical eNergy Delivery System). FRIENDS is a new concept of power distribution system which can realize unbundled power quality services under de-regulated conditions. In order to realize FRIENDS, a system network configuration of FRIENDS itself must be developed. For unbundled power quality services, and especially for reliable power supply, the authors propose a new algorithm to create a network of FRIENDS. The proposed method is based on the tabu search method, and can find the least cost network configuration of FRIENDS under the constraint that no overloads exist in multiple fault cases.","PeriodicalId":434526,"journal":{"name":"Proceedings of EMPD '98. 1998 International Conference on Energy Management and Power Delivery (Cat. No.98EX137)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117283303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Extension to a local multimachine control system with output feedback","authors":"K. Ohtsuka, Y. Morioka","doi":"10.1109/EMPD.1998.705408","DOIUrl":"https://doi.org/10.1109/EMPD.1998.705408","url":null,"abstract":"A multimachine control system is investigated to enhance the stability of a local multimachine power system connected to a large-scale primary power system. The control system is designed on the basis of the modern control theory. The system is first designed in the form of state feedback. For much easier applications, a practical extension to a control system with output feedback is investigated.","PeriodicalId":434526,"journal":{"name":"Proceedings of EMPD '98. 1998 International Conference on Energy Management and Power Delivery (Cat. No.98EX137)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128565748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Hybrid switching: a review of current literature","authors":"A.M.S. Atmadji, J. Sloot","doi":"10.1109/EMPD.1998.702771","DOIUrl":"https://doi.org/10.1109/EMPD.1998.702771","url":null,"abstract":"Modern interconnected power systems can lead to much more energy being released when a short-circuit occurs; consequently, there is a greater need for current limiting devices. Such devices must react quickly but, fortunately, the latest semiconductor technology allows that to be done with the aid of hybrid switching. In this article, a review of recent developments in hybrid switching for high current electrical systems is presented. Attention is focused on combinations of mechanical and solid-state switches for both contactors and short-circuit current breakers. Finally, their commercial applications are also given.","PeriodicalId":434526,"journal":{"name":"Proceedings of EMPD '98. 1998 International Conference on Energy Management and Power Delivery (Cat. No.98EX137)","volume":"155 12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128680110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An ANN and wavelet transformation based method for short term load forecast","authors":"Ma Ning, Yunping Chen","doi":"10.1109/EMPD.1998.702587","DOIUrl":"https://doi.org/10.1109/EMPD.1998.702587","url":null,"abstract":"A new method for short term load forecast based on an artificial neural network (ANN) and wavelet transformation is presented in this paper. The load series is mapped onto some sub-series with wavelet transformation and then the sub-series are forecast by ANN. Weather factors are taken into account in forecasting. After all sub-series of load series are forecast, the whole predicted load series can be composed or reconstructed. In addition, a new BP algorithm is proposed to speed up the training process and improve the convergence of the ANN. All experimental results show the correctness of the principles proposed and the feasibility of the algorithm.","PeriodicalId":434526,"journal":{"name":"Proceedings of EMPD '98. 1998 International Conference on Energy Management and Power Delivery (Cat. No.98EX137)","volume":"95 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126821713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Modelling of on-load tap-changer transformer with variable impedance and its applications","authors":"Jiangwei Fan, Z. Bo","doi":"10.1109/EMPD.1998.702713","DOIUrl":"https://doi.org/10.1109/EMPD.1998.702713","url":null,"abstract":"In power system fault analysis, an on-load tap-changer transformer is normally presented in terms of its leakage impedance at nominal tap position. However the operational position of an OLTCT is deviated from its nominal position, resulting in the actual impedance differing from its nominal value due to the different turns ratio. The variation of transformer impedance introduces error in fault calculations which may affect the setting of numerical protection relays and the selection of circuit breaker rating. This paper presents a new model of an on-load tap changer transformer to improve the accuracy of fault calculation.","PeriodicalId":434526,"journal":{"name":"Proceedings of EMPD '98. 1998 International Conference on Energy Management and Power Delivery (Cat. No.98EX137)","volume":"191 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126788141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Latest developments in direct EV wheel drives","authors":"B. Hredzak, P. Chin, S. Gair","doi":"10.1109/EMPD.1998.702777","DOIUrl":"https://doi.org/10.1109/EMPD.1998.702777","url":null,"abstract":"Traditionally electric vehicles used an electric motor which simply replaced the combustion engine, and all the mechanical components were kept. Direct wheel drives in electric vehicles are advantageous because the gearbox, mechanical transmission and differential can be eliminated. Usually, the drive motor is mounted in the road wheel of the vehicle. However this results in the increase of the unsprung mass of the vehicle due to the weight of the drive motor. This can be overcome by using a double sided axial field machine with a central rotor. The stators of the machine can be attached to the chassis of the car whilst the rotor directly drives the road wheel. This paper investigates problems associated with this novel drive and proposes control techniques which can be employed in order to ensure safe operation of the vehicle.","PeriodicalId":434526,"journal":{"name":"Proceedings of EMPD '98. 1998 International Conference on Energy Management and Power Delivery (Cat. No.98EX137)","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116883084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A new generation of control and diagnostic techniques for gas insulated switchgear","authors":"U. Katschinski, W. Olszewski, T. Schaeffler","doi":"10.1109/EMPD.1998.702756","DOIUrl":"https://doi.org/10.1109/EMPD.1998.702756","url":null,"abstract":"New secondary systems on the bay and station levels of high-voltage substations with gas insulated switchgear (GIS) offer the opportunity for an optimisation of reliability, together with a reduction of the life cycle cost, of the GIS. These goals can be reached by decreasing the outage time of the switchgear, by reducing failures in service, by new more effective maintenance strategies and by optimizing the utilization of the switchgear. For all these measures, more information about the status of the switchgear is necessary. Modern secondary equipment capable of providing these information is characterized by a systematic use of serial data bus connections replacing the parallel wiring of conventional GIS bays. A major communication link of this system is the process bus. It connects all installed devices in the bay, e.g. circuit breaker, disconnector/earthing switches, current and voltage transducers etc., with the bay related control and protection devices. Major devices are intelligent modules equipped with their own small computers performing the main monitoring and diagnostic functions independently. The computers acquire the data from a number of sensors, process them and transmit the information onto the data bus system. Vice versa they receive information from the data bus system and activate actuators if necessary. This GIS design offers opportunities to apply new diagnostic technologies which can detect a wide range of physical variables. The control and communication system as well as the diagnostic system are described in detail.","PeriodicalId":434526,"journal":{"name":"Proceedings of EMPD '98. 1998 International Conference on Energy Management and Power Delivery (Cat. No.98EX137)","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121450208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A specially designed EV PM motor drive","authors":"W. Xia, P. Chin","doi":"10.1109/EMPD.1998.702778","DOIUrl":"https://doi.org/10.1109/EMPD.1998.702778","url":null,"abstract":"A specially designed electric vehicle (EV) PM motor drive is developed. The new PM phase decoupling brushless DC motor possesses the advantages of high power density, high efficiency, simple mathematical model and good torque performance. Meanwhile, a high speed efficiency-optimising control scheme is proposed for the motor. The high speed constant power operation is achieved in such a way that the transformer EMF is used to counteract the enlarged rotational EMF when the motor operates above the base speed. To obtain the efficiency optimising control, the advanced conduction angle is adaptively adjusted to minimise the system losses for a given operating point in the high speed region. Both simulation and experimental results are given in the paper.","PeriodicalId":434526,"journal":{"name":"Proceedings of EMPD '98. 1998 International Conference on Energy Management and Power Delivery (Cat. No.98EX137)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122089254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Consideration of insolation characteristics in sizing stand-alone PV stations","authors":"G. Shrestha","doi":"10.1109/EMPD.1998.702762","DOIUrl":"https://doi.org/10.1109/EMPD.1998.702762","url":null,"abstract":"Stand-alone PV schemes have found a fairly wide application in remote isolated regions to meet small but essential electric load. The capacities of such stations are commonly specified in terms of the peak power available during maximum solar insolation. The actual insolation available at a site is, however, affected by the vagaries of the weather in addition to the seasonal and diurnal variation. The support for these systems to cover for the periods of low insolation levels is provided by the battery system. The variation of insolation can be quite drastic and the peak rating may not be a proper measure of the station capacity. This paper analyzes the statistical nature of the available insolation using historical data collected at an experimental PV station. It attempts to determine the appropriate statistical distribution for the insolation level. This representation is then used to simulate the operation of stand alone PV stations probabilistically using different station configurations to evaluate their performance. An interactive software package has been developed using MATLAB to carry out the insolation data analysis and to simulate the operation of such schemes. The details regarding: (i) the modeling of various components; (ii) the features of the software package; and (iii) typical simulation results and their applications, are presented.","PeriodicalId":434526,"journal":{"name":"Proceedings of EMPD '98. 1998 International Conference on Energy Management and Power Delivery (Cat. No.98EX137)","volume":"317 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116603251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}