Pub Date : 1995-05-07DOI: 10.1109/PICA.1995.515285
Jin-Cheng Wang, H. Chiang, G. Darling
Real-time applications demand fast computation, and this paper proposes an efficient algorithm for real-time network reconfiguration on large unbalanced distribution networks. A novel formulation of the network reconfiguration to achieve loss minimization and load balancing is given. To reduce computational requirements for the solution algorithm, well justified power flow and loss reduction formulae in terms of the on/off status of network switches are proposed for efficient system updating. The algorithm relies only on a few full power flow studies based on system states attained by explicit expressions using backward-forward sweeps for efficient computation of power system states at the critical system operating points. The solution algorithm runs in an amount of time linearly proportional to the number of tie switches and the number of sectionalizing switches in the system. The solution algorithm has been implemented into a software package and tested on unbalanced distribution systems including a system with 292 buses, 76 laterals, 7 transformers, 45 switches and 255 line sections under diverse system conditions.
{"title":"An efficient algorithm for real-time network reconfiguration in large scale unbalanced distribution systems","authors":"Jin-Cheng Wang, H. Chiang, G. Darling","doi":"10.1109/PICA.1995.515285","DOIUrl":"https://doi.org/10.1109/PICA.1995.515285","url":null,"abstract":"Real-time applications demand fast computation, and this paper proposes an efficient algorithm for real-time network reconfiguration on large unbalanced distribution networks. A novel formulation of the network reconfiguration to achieve loss minimization and load balancing is given. To reduce computational requirements for the solution algorithm, well justified power flow and loss reduction formulae in terms of the on/off status of network switches are proposed for efficient system updating. The algorithm relies only on a few full power flow studies based on system states attained by explicit expressions using backward-forward sweeps for efficient computation of power system states at the critical system operating points. The solution algorithm runs in an amount of time linearly proportional to the number of tie switches and the number of sectionalizing switches in the system. The solution algorithm has been implemented into a software package and tested on unbalanced distribution systems including a system with 292 buses, 76 laterals, 7 transformers, 45 switches and 255 line sections under diverse system conditions.","PeriodicalId":294493,"journal":{"name":"Proceedings of Power Industry Computer Applications Conference","volume":"123 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134609664","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}
Pub Date : 1995-05-07DOI: 10.1109/PICA.1995.515178
A. T. Dasigenis, A.R. Garcia-San Pedro
This paper addresses the real-time aspects of the hydro-thermal coordination problem. It describes the real-time modeling and monitoring of hydro resources, and the use of the resulting real-time hydraulic data in the online economic dispatch algorithm. A variable head, hydro loss model is incorporated that allows for online changes to the hydro topology. The method presented provides the operator with a current view of the available water resources, enables the validation of the real-time hydro data received from the field, and enables real-time optimization of the hydro-thermal unit commitment plan. The implementation of this approach on the Iberdrola system in Spain is described.
{"title":"Real-time hydro coordination and economic hydro optimization","authors":"A. T. Dasigenis, A.R. Garcia-San Pedro","doi":"10.1109/PICA.1995.515178","DOIUrl":"https://doi.org/10.1109/PICA.1995.515178","url":null,"abstract":"This paper addresses the real-time aspects of the hydro-thermal coordination problem. It describes the real-time modeling and monitoring of hydro resources, and the use of the resulting real-time hydraulic data in the online economic dispatch algorithm. A variable head, hydro loss model is incorporated that allows for online changes to the hydro topology. The method presented provides the operator with a current view of the available water resources, enables the validation of the real-time hydro data received from the field, and enables real-time optimization of the hydro-thermal unit commitment plan. The implementation of this approach on the Iberdrola system in Spain is described.","PeriodicalId":294493,"journal":{"name":"Proceedings of Power Industry Computer Applications Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128246770","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}
Pub Date : 1995-05-07DOI: 10.1109/PICA.1995.515276
W. Dieterle, H. Kochs, E. Dittmar
The use of energy management systems (EMS) demands high reliability, real-time behaviour and more and more economical systems. The last demand requires the use of inexpensive standard components, whenever possible. The following article discusses the realization of EMS, especially system communication, with respect to these constraints. Problems due to conventional use of standardized communication protocols in distributed supervisory systems in general and highly-reliable systems in particular are shown. Multicast communication concepts are presented as solutions, using standardized protocols in a problem specific way. The presented concepts fulfill the necessity of using standard components as wed as the specific demands towards EMS.
{"title":"LAN based data communication in modern energy management systems (EMS)","authors":"W. Dieterle, H. Kochs, E. Dittmar","doi":"10.1109/PICA.1995.515276","DOIUrl":"https://doi.org/10.1109/PICA.1995.515276","url":null,"abstract":"The use of energy management systems (EMS) demands high reliability, real-time behaviour and more and more economical systems. The last demand requires the use of inexpensive standard components, whenever possible. The following article discusses the realization of EMS, especially system communication, with respect to these constraints. Problems due to conventional use of standardized communication protocols in distributed supervisory systems in general and highly-reliable systems in particular are shown. Multicast communication concepts are presented as solutions, using standardized protocols in a problem specific way. The presented concepts fulfill the necessity of using standard components as wed as the specific demands towards EMS.","PeriodicalId":294493,"journal":{"name":"Proceedings of Power Industry Computer Applications Conference","volume":"197 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132663690","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}
Pub Date : 1995-05-07DOI: 10.1109/PICA.1995.515290
L. Escudero, C. García, J. L. de la Fuente, F. Prieto
We present a modeling framework for the robust solution of hydroelectric power management problems with uncertainty in the values of the water inflows and outflows. A deterministic treatment of the problem provides unsatisfactory results, except for very short time horizons. We describe a model based on scenario analysis that allows a satisfactory treatment of uncertainty in the model data for medium and long-term planning problems. Our approach results in a huge model with a network submodel per scenario plus coupling constraints. The size of the problem and the structure of the constraints are adequate for the use of decomposition techniques and parallel computation tools. We present computational results for both sequential and parallel implementation versions of the codes, running on a cluster of workstations. The codes have been tested on data obtained from the reservoir network of Iberdrola, a power utility owning 50% of the total installed hydroelectric capacity of Spain, and generating 40% of the total energy demand.
{"title":"Hydropower generation management under uncertainty via scenario analysis and parallel computation","authors":"L. Escudero, C. García, J. L. de la Fuente, F. Prieto","doi":"10.1109/PICA.1995.515290","DOIUrl":"https://doi.org/10.1109/PICA.1995.515290","url":null,"abstract":"We present a modeling framework for the robust solution of hydroelectric power management problems with uncertainty in the values of the water inflows and outflows. A deterministic treatment of the problem provides unsatisfactory results, except for very short time horizons. We describe a model based on scenario analysis that allows a satisfactory treatment of uncertainty in the model data for medium and long-term planning problems. Our approach results in a huge model with a network submodel per scenario plus coupling constraints. The size of the problem and the structure of the constraints are adequate for the use of decomposition techniques and parallel computation tools. We present computational results for both sequential and parallel implementation versions of the codes, running on a cluster of workstations. The codes have been tested on data obtained from the reservoir network of Iberdrola, a power utility owning 50% of the total installed hydroelectric capacity of Spain, and generating 40% of the total energy demand.","PeriodicalId":294493,"journal":{"name":"Proceedings of Power Industry Computer Applications Conference","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114200225","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}
Pub Date : 1995-05-07DOI: 10.1109/PICA.1995.515283
A. Cohen, G. Ostrowski
The operating flexibility of certain types of generating units can be exploited to reduce the production cost of their power system. These units have different operating modes where the operating parameters can differ greatly depending which mode is operating at the time. Examples of such units are: combined cycle; fuel switching/blending; constant/variable pressure; overfire; and dual boiler. A general modeling approach is described which can be used to model units with multiple operating modes. It is shown how Lagrangian relaxation can be used to schedule these units. Examples are given showing the benefit of using these methods to schedule an electric utility's power system.
{"title":"Scheduling units with multiple operating modes in unit commitment","authors":"A. Cohen, G. Ostrowski","doi":"10.1109/PICA.1995.515283","DOIUrl":"https://doi.org/10.1109/PICA.1995.515283","url":null,"abstract":"The operating flexibility of certain types of generating units can be exploited to reduce the production cost of their power system. These units have different operating modes where the operating parameters can differ greatly depending which mode is operating at the time. Examples of such units are: combined cycle; fuel switching/blending; constant/variable pressure; overfire; and dual boiler. A general modeling approach is described which can be used to model units with multiple operating modes. It is shown how Lagrangian relaxation can be used to schedule these units. Examples are given showing the benefit of using these methods to schedule an electric utility's power system.","PeriodicalId":294493,"journal":{"name":"Proceedings of Power Industry Computer Applications Conference","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122589492","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}
Pub Date : 1995-05-07DOI: 10.1109/PICA.1995.515174
J. Gronquist, W. Sethares, F. Alvarado, R. Lasseter
This paper presents an exact mechanical analog for an electric power system that proves to be a powerful visualization tool for studying power systems issues such as load flow, transient stability, and the effects of FACTS devices. Techniques based on color and highlighting that make the method applicable to the visualization of large systems are introduced. The analog provides a means for demonstrating complex issues to audiences with little or no background in power systems. For the power engineer, the analog provides unique insights into the hows and whys of power system behavior. To the control center operator, an accurate model of the dynamic modes may bring about improved understanding of system behavior after contingencies and illustrate the relative merits of various dispatch options.
{"title":"Animated vectors for visualization of power system phenomena","authors":"J. Gronquist, W. Sethares, F. Alvarado, R. Lasseter","doi":"10.1109/PICA.1995.515174","DOIUrl":"https://doi.org/10.1109/PICA.1995.515174","url":null,"abstract":"This paper presents an exact mechanical analog for an electric power system that proves to be a powerful visualization tool for studying power systems issues such as load flow, transient stability, and the effects of FACTS devices. Techniques based on color and highlighting that make the method applicable to the visualization of large systems are introduced. The analog provides a means for demonstrating complex issues to audiences with little or no background in power systems. For the power engineer, the analog provides unique insights into the hows and whys of power system behavior. To the control center operator, an accurate model of the dynamic modes may bring about improved understanding of system behavior after contingencies and illustrate the relative merits of various dispatch options.","PeriodicalId":294493,"journal":{"name":"Proceedings of Power Industry Computer Applications Conference","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122205104","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}
Pub Date : 1995-05-07DOI: 10.1109/PICA.1995.515187
T. Goeke, W. Wellssow
Problems usually arise when predicting harmonics in public supply systems due to the varying characteristics of the loads connected. Based on comprehensive measurements, a statistical load model is set up providing the harmonic parameters of all LV systems fed by the same HV/MV feeder. Harmonic distortion in the MV system caused by the variety of stochastic LV customers is determined by a Monte Carlo simulation approach applying the load model.
{"title":"A statistical approach to the calculation of harmonics in MV systems caused by dispersed LV customers","authors":"T. Goeke, W. Wellssow","doi":"10.1109/PICA.1995.515187","DOIUrl":"https://doi.org/10.1109/PICA.1995.515187","url":null,"abstract":"Problems usually arise when predicting harmonics in public supply systems due to the varying characteristics of the loads connected. Based on comprehensive measurements, a statistical load model is set up providing the harmonic parameters of all LV systems fed by the same HV/MV feeder. Harmonic distortion in the MV system caused by the variety of stochastic LV customers is determined by a Monte Carlo simulation approach applying the load model.","PeriodicalId":294493,"journal":{"name":"Proceedings of Power Industry Computer Applications Conference","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123332353","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}
Pub Date : 1900-01-01DOI: 10.1109/PICA.1995.515291
J. Saraiva, Vladimiro Miranda, L. Pinto
This paper presents a Monte Carlo algorithm considering loads defined by fuzzy numbers. In this methodology states are sampled according to the probabilistic models governing the life cycle of system components while fuzzy concepts are used to model uncertainty related to future load behavior. This model can be used to evaluate generation/transmission power system reliability for long term planning studies as one uses the more adequate uncertainty models for each type of data. For each sampled state a fuzzy optimal power flow is run so that one builds its power not supplied membership function. The paper proposes new indices reflecting the integration of probabilistic models and fuzzy concepts and discusses the application of variance reduction techniques if loads are defined by fuzzy numbers. A case-study based on the IEEE 30 bus system illustrates this methodology.
{"title":"Generation/transmission power system reliability evaluation by Monte Carlo simulation assuming a fuzzy load description","authors":"J. Saraiva, Vladimiro Miranda, L. Pinto","doi":"10.1109/PICA.1995.515291","DOIUrl":"https://doi.org/10.1109/PICA.1995.515291","url":null,"abstract":"This paper presents a Monte Carlo algorithm considering loads defined by fuzzy numbers. In this methodology states are sampled according to the probabilistic models governing the life cycle of system components while fuzzy concepts are used to model uncertainty related to future load behavior. This model can be used to evaluate generation/transmission power system reliability for long term planning studies as one uses the more adequate uncertainty models for each type of data. For each sampled state a fuzzy optimal power flow is run so that one builds its power not supplied membership function. The paper proposes new indices reflecting the integration of probabilistic models and fuzzy concepts and discusses the application of variance reduction techniques if loads are defined by fuzzy numbers. A case-study based on the IEEE 30 bus system illustrates this methodology.","PeriodicalId":294493,"journal":{"name":"Proceedings of Power Industry Computer Applications Conference","volume":"95 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121598917","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}
Pub Date : 1900-01-01DOI: 10.1109/PICA.1995.515273
H.J. Altuve F., I. Diaz V., E. Vázquez M
Filtering requirements for power system distance relays are very critical, because they must estimate precisely and quickly the electrical distance to the fault, even with highly distorted input signals. A number of digital filtering algorithms for distance relays have been proposed and some of them are in use in practical relays; however, power system evolution increases the corruption level of signals and imposes the necessity of continuing the research efforts in this area. In the present paper, a comparative evaluation of different digital filtering algorithms for distance protection is performed. An evaluation method is proposed, which gives comprehensive information about filter transient behavior over a wide frequency range of noise. The discussion is focused in well-known algorithms based on Fourier and Walsh transforms, and includes a recently proposed combined sine-cosine filter.
{"title":"Fourier and Walsh digital filtering algorithms for distance protection","authors":"H.J. Altuve F., I. Diaz V., E. Vázquez M","doi":"10.1109/PICA.1995.515273","DOIUrl":"https://doi.org/10.1109/PICA.1995.515273","url":null,"abstract":"Filtering requirements for power system distance relays are very critical, because they must estimate precisely and quickly the electrical distance to the fault, even with highly distorted input signals. A number of digital filtering algorithms for distance relays have been proposed and some of them are in use in practical relays; however, power system evolution increases the corruption level of signals and imposes the necessity of continuing the research efforts in this area. In the present paper, a comparative evaluation of different digital filtering algorithms for distance protection is performed. An evaluation method is proposed, which gives comprehensive information about filter transient behavior over a wide frequency range of noise. The discussion is focused in well-known algorithms based on Fourier and Walsh transforms, and includes a recently proposed combined sine-cosine filter.","PeriodicalId":294493,"journal":{"name":"Proceedings of Power Industry Computer Applications Conference","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128756868","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}
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