Pub Date : 2001-07-15DOI: 10.1109/PESS.2001.970237
S. Heunis, R. Herman
The voltage drop in a feeder is aggravated by the imbalance of single-phase loads connected to the phases of a multi-phase distribution network can be appreciable. It is particularly important In long radial low voltage feeders when the voltage drop in the feeder Is the major sizing criterion. This applies equally to existing or to new plant. Significant enhancement in the voltage performance of a multi-phase feeder feeding single-phase customers may be obtained by configuring the customer connection schedule in an optimal way. A method of achieving this is proposed in this paper. The method is based on the principle of superposition and is applied to a probabilistic voltage drop calculation procedure. Simple examples are given to illustrate the method but it has been applied to more complex networks in practice. Although the method was developed for low voltage feeders, the principles are applicable at any voltage level with some modification.
{"title":"A load reconfiguration algorithm for optimizing LV residential feeders with voltage performance as the criterion","authors":"S. Heunis, R. Herman","doi":"10.1109/PESS.2001.970237","DOIUrl":"https://doi.org/10.1109/PESS.2001.970237","url":null,"abstract":"The voltage drop in a feeder is aggravated by the imbalance of single-phase loads connected to the phases of a multi-phase distribution network can be appreciable. It is particularly important In long radial low voltage feeders when the voltage drop in the feeder Is the major sizing criterion. This applies equally to existing or to new plant. Significant enhancement in the voltage performance of a multi-phase feeder feeding single-phase customers may be obtained by configuring the customer connection schedule in an optimal way. A method of achieving this is proposed in this paper. The method is based on the principle of superposition and is applied to a probabilistic voltage drop calculation procedure. Simple examples are given to illustrate the method but it has been applied to more complex networks in practice. Although the method was developed for low voltage feeders, the principles are applicable at any voltage level with some modification.","PeriodicalId":273578,"journal":{"name":"2001 Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.01CH37262)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132111545","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 : 2001-07-15DOI: 10.1109/PESS.2001.970153
J. Wikston
IEEE Std 519 (1981 and 1992) have established limits for harmonic voltage and current levels at the point of common coupling (PCC). The 1981 edition also had limits for some dedicated buses within a facility. This paper proposes limits for low voltage buses (<1 kV) within a facility to be included in the next 519 revision.
{"title":"Limits for low voltage (<1 kV) buses","authors":"J. Wikston","doi":"10.1109/PESS.2001.970153","DOIUrl":"https://doi.org/10.1109/PESS.2001.970153","url":null,"abstract":"IEEE Std 519 (1981 and 1992) have established limits for harmonic voltage and current levels at the point of common coupling (PCC). The 1981 edition also had limits for some dedicated buses within a facility. This paper proposes limits for low voltage buses (<1 kV) within a facility to be included in the next 519 revision.","PeriodicalId":273578,"journal":{"name":"2001 Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.01CH37262)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130283289","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 : 2001-07-15DOI: 10.1109/PESS.2001.970082
T. Taylor
It will become increasingly more important to be able to estimate the cost of achieving a given level of reliability for a distribution company. Specifically, if baseline values of reliability are to be established by utility regulators, distribution companies need to understand the amount of expenditure required to reach a particular level of reliability. There is no easy method to do this, but distribution engineers and planners play a key role in estimating the cost of obtaining a given level of reliability. From a distribution engineering perspective, the first step to determine the costs needed to achieve a given level of reliability is the review of system design audit and review of past performance. This generates insight into the underlying causes of poor reliability. This is a necessary first step in being able to gauge how reliability-improvement funds can be spent most effectively. The system design audit involves a physical inspection of representative areas of the distribution system. During the audit, it is also important for the auditor to have discussions with area engineers and operating personnel to gain their perspective on the root causes of reliability problems.
{"title":"Estimating costs to achieve particular levels of reliability","authors":"T. Taylor","doi":"10.1109/PESS.2001.970082","DOIUrl":"https://doi.org/10.1109/PESS.2001.970082","url":null,"abstract":"It will become increasingly more important to be able to estimate the cost of achieving a given level of reliability for a distribution company. Specifically, if baseline values of reliability are to be established by utility regulators, distribution companies need to understand the amount of expenditure required to reach a particular level of reliability. There is no easy method to do this, but distribution engineers and planners play a key role in estimating the cost of obtaining a given level of reliability. From a distribution engineering perspective, the first step to determine the costs needed to achieve a given level of reliability is the review of system design audit and review of past performance. This generates insight into the underlying causes of poor reliability. This is a necessary first step in being able to gauge how reliability-improvement funds can be spent most effectively. The system design audit involves a physical inspection of representative areas of the distribution system. During the audit, it is also important for the auditor to have discussions with area engineers and operating personnel to gain their perspective on the root causes of reliability problems.","PeriodicalId":273578,"journal":{"name":"2001 Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.01CH37262)","volume":"458 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133863877","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 : 2001-07-15DOI: 10.1109/PESS.2001.970323
S. Yanagawa, T. Kato, W. Kai, A. Tabata, Y. Yokomizu, T. Okamoto, Y. Suzuoki
The output of a photovoltaic power generation system (PV system) fluctuates depending on weather conditions. Large-scale introduction of PV systems may cause some difficulties in the operation of an electric power system. The evaluation of the influence of PV systems on the power system operation should consider the smoothing effect of the outputs by the dispersed introduction of PV systems. This paper discusses the LFC (load frequency control) capacity for output fluctuation of PV systems based on the insolation data simultaneously observed at 5 points around Nagoya, Japan. As a result, when the weather was clear but clouds moved frequently, the capacity. for LFC based on the regional averaged insolation was evaluated less than a half of that evaluated by the insolation at one point. Furthermore, LFC capacity might be dominated by the speed factor rather than the magnitude factor of load fluctuation including PV system's output when a large capacity of PV systems is installed.
{"title":"Evaluation of LFC capacity for output fluctuation of photovoltaic power generation systems based on multi-point observation of insolation","authors":"S. Yanagawa, T. Kato, W. Kai, A. Tabata, Y. Yokomizu, T. Okamoto, Y. Suzuoki","doi":"10.1109/PESS.2001.970323","DOIUrl":"https://doi.org/10.1109/PESS.2001.970323","url":null,"abstract":"The output of a photovoltaic power generation system (PV system) fluctuates depending on weather conditions. Large-scale introduction of PV systems may cause some difficulties in the operation of an electric power system. The evaluation of the influence of PV systems on the power system operation should consider the smoothing effect of the outputs by the dispersed introduction of PV systems. This paper discusses the LFC (load frequency control) capacity for output fluctuation of PV systems based on the insolation data simultaneously observed at 5 points around Nagoya, Japan. As a result, when the weather was clear but clouds moved frequently, the capacity. for LFC based on the regional averaged insolation was evaluated less than a half of that evaluated by the insolation at one point. Furthermore, LFC capacity might be dominated by the speed factor rather than the magnitude factor of load fluctuation including PV system's output when a large capacity of PV systems is installed.","PeriodicalId":273578,"journal":{"name":"2001 Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.01CH37262)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131713753","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 : 2001-07-15DOI: 10.1109/PESS.2001.970026
A. Prudenzi, U. Grasselli, R. Lamedica
The paper deals with the harmonic emission limits provided by International Electrotechnical Commission (IEC) Std. 61000-3-2 for appliances with current absorption less than or equal to 16 Amps. To this aim attention is focussed on personal computers (PC) as a sample of the wide nonlinear appliance class D as regulated by the Standard. Results of some laboratory tests on a PC supplied from the low voltage (LV) grid show that: (1) EEC limits expressed to mA/W are exceeded by actual PCs operating In practical systems; and (2) the IEC limits are stated for nominal load even though lower loading conditions produce higher specific (mA/W) harmonic contents. The problems are assessed by means of a testing activity performed in the laboratory. To this aim, an experimental layout providing harmonic monitoring of a PC supplied from a system with variable impedance has been implemented in the laboratory.
{"title":"IEC Std. 61000-3-2 harmonic current emission limits in practical systems: need of considering loading level and attenuation effects","authors":"A. Prudenzi, U. Grasselli, R. Lamedica","doi":"10.1109/PESS.2001.970026","DOIUrl":"https://doi.org/10.1109/PESS.2001.970026","url":null,"abstract":"The paper deals with the harmonic emission limits provided by International Electrotechnical Commission (IEC) Std. 61000-3-2 for appliances with current absorption less than or equal to 16 Amps. To this aim attention is focussed on personal computers (PC) as a sample of the wide nonlinear appliance class D as regulated by the Standard. Results of some laboratory tests on a PC supplied from the low voltage (LV) grid show that: (1) EEC limits expressed to mA/W are exceeded by actual PCs operating In practical systems; and (2) the IEC limits are stated for nominal load even though lower loading conditions produce higher specific (mA/W) harmonic contents. The problems are assessed by means of a testing activity performed in the laboratory. To this aim, an experimental layout providing harmonic monitoring of a PC supplied from a system with variable impedance has been implemented in the laboratory.","PeriodicalId":273578,"journal":{"name":"2001 Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.01CH37262)","volume":"258 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130797495","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 : 2001-07-15DOI: 10.1109/PESS.2001.970307
Yongqiang Liu, Jie Wu, Y. Ni, F. Wu
The problem of voltage collapse in the power system occurs when the load parameter exceeds some critical value. The critical operation point is known as the nose point in the P-V curve. In this paper, the mechanism of voltage collapse is explained based on system circuit and solution manifolds. The corresponding mathematical model is derived. The proven theorem shows that the essential reason for voltage collapse is that the solution manifold of injection branch equations being not transversal with that of linear network equations. The coincidence of the nontransversal of solution manifolds with voltage collapse and static bifurcation is proved.
{"title":"Voltage collapse mechanism based on system circuit and its solution manifolds","authors":"Yongqiang Liu, Jie Wu, Y. Ni, F. Wu","doi":"10.1109/PESS.2001.970307","DOIUrl":"https://doi.org/10.1109/PESS.2001.970307","url":null,"abstract":"The problem of voltage collapse in the power system occurs when the load parameter exceeds some critical value. The critical operation point is known as the nose point in the P-V curve. In this paper, the mechanism of voltage collapse is explained based on system circuit and solution manifolds. The corresponding mathematical model is derived. The proven theorem shows that the essential reason for voltage collapse is that the solution manifold of injection branch equations being not transversal with that of linear network equations. The coincidence of the nontransversal of solution manifolds with voltage collapse and static bifurcation is proved.","PeriodicalId":273578,"journal":{"name":"2001 Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.01CH37262)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130900881","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 : 2001-07-15DOI: 10.1109/PESS.2001.970196
S. Naka, T. Genji, Y. Fukuyama
This paper presents distribution system equipment models for fast distribution load flow calculation considering interconnection of distributed generators. Recently, the number of distributed generators introduced into distribution systems has been increasing, and detailed system analysis using load flow calculation has been eagerly awaited. This paper develops practical equipment models such as various distributed generators, voltage control equipment, and loads. The feasibility of the developed models is verified and demonstrated on practical distribution system models with promising results.
{"title":"Practical equipment models for fast distribution power flow considering interconnection of distributed generators","authors":"S. Naka, T. Genji, Y. Fukuyama","doi":"10.1109/PESS.2001.970196","DOIUrl":"https://doi.org/10.1109/PESS.2001.970196","url":null,"abstract":"This paper presents distribution system equipment models for fast distribution load flow calculation considering interconnection of distributed generators. Recently, the number of distributed generators introduced into distribution systems has been increasing, and detailed system analysis using load flow calculation has been eagerly awaited. This paper develops practical equipment models such as various distributed generators, voltage control equipment, and loads. The feasibility of the developed models is verified and demonstrated on practical distribution system models with promising results.","PeriodicalId":273578,"journal":{"name":"2001 Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.01CH37262)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131164362","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 : 2001-07-15DOI: 10.1109/PESS.2001.970001
J. Hrabliuk
Optical current sensors are achieving increased acceptance and use in high voltage substations due to their superior accuracy, bandwidth, dynamic range and inherent isolation. Once deemed specialized devices intended for novel applications, optical sensors have risen to a performance level exceeding conventional magnetic devices. Optical current sensors have pushed the limits of measurement beyond what is presently available with conventional technology. In order for users of optical transducers to realize the complete benefits available from this new technology, an understanding of the differences between conventional transformers and optical sensors is critical. Key users who must understand these differences include planners, apparatus engineers, substation designers, maintenance personnel and system operators. Interfacing optical sensors to existing meters and relays is one of these key differences and is the primary focus of this paper. Providing a simple method of interconnecting old and new technology is a necessary and required step in the path to acceptance of optical sensors, and if given this, it will ease the transition to advanced systems within a substation.
{"title":"Interfacing optical current sensors in a substation","authors":"J. Hrabliuk","doi":"10.1109/PESS.2001.970001","DOIUrl":"https://doi.org/10.1109/PESS.2001.970001","url":null,"abstract":"Optical current sensors are achieving increased acceptance and use in high voltage substations due to their superior accuracy, bandwidth, dynamic range and inherent isolation. Once deemed specialized devices intended for novel applications, optical sensors have risen to a performance level exceeding conventional magnetic devices. Optical current sensors have pushed the limits of measurement beyond what is presently available with conventional technology. In order for users of optical transducers to realize the complete benefits available from this new technology, an understanding of the differences between conventional transformers and optical sensors is critical. Key users who must understand these differences include planners, apparatus engineers, substation designers, maintenance personnel and system operators. Interfacing optical sensors to existing meters and relays is one of these key differences and is the primary focus of this paper. Providing a simple method of interconnecting old and new technology is a necessary and required step in the path to acceptance of optical sensors, and if given this, it will ease the transition to advanced systems within a substation.","PeriodicalId":273578,"journal":{"name":"2001 Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.01CH37262)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130727580","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 : 2001-07-15DOI: 10.1109/PESS.2001.970365
L. Mokhnache, A. Boubakeur, B. Noureddine, M. Bedja, A. Feliachi
Studies on transformer oil thermal ageing were carried out at the ENP Laboratory. The oil, named BORAK22, is used by the Algerian national electric and gas company (SONELGAZ). Experiments were performed at different temperatures with a maximum ageing duration time of 2000 hours. The objective is to build a neural network that gives a good prediction of the nonlinear property variations of the material versus the ageing time, and whose learning time is clearly less than the laboratory test time. The chosen network is a radial basis function Gaussian network (RBFG) trained by the ROM (random optimisation method) and uses the FFN pattern and the batch learning techniques. The designed network gave a good prediction with a relative error of 5% and 3% for the two learning techniques respectively.
{"title":"Application of neural networks in the thermal ageing prediction of transformer oil","authors":"L. Mokhnache, A. Boubakeur, B. Noureddine, M. Bedja, A. Feliachi","doi":"10.1109/PESS.2001.970365","DOIUrl":"https://doi.org/10.1109/PESS.2001.970365","url":null,"abstract":"Studies on transformer oil thermal ageing were carried out at the ENP Laboratory. The oil, named BORAK22, is used by the Algerian national electric and gas company (SONELGAZ). Experiments were performed at different temperatures with a maximum ageing duration time of 2000 hours. The objective is to build a neural network that gives a good prediction of the nonlinear property variations of the material versus the ageing time, and whose learning time is clearly less than the laboratory test time. The chosen network is a radial basis function Gaussian network (RBFG) trained by the ROM (random optimisation method) and uses the FFN pattern and the batch learning techniques. The designed network gave a good prediction with a relative error of 5% and 3% for the two learning techniques respectively.","PeriodicalId":273578,"journal":{"name":"2001 Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.01CH37262)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133704332","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 : 2001-07-15DOI: 10.1109/PESS.2001.970027
L. Snider, E. Lo, T. Lai
The proliferation of nonlinear loads resulting from new technologies has increased the levels of harmonics in power systems, and traction systems represent large nonlinear loads. This paper presents results of a simulation of the harmonics related to a mass transit railway system. Railway simulation results from the ATP version of Electromagnetic Transient Program (EMTP) with train schedules are presented. Summaries of the parameters affecting the harmonic performance of the traction system and estimates of the most predominant harmonics in a network are also presented and recommendations are made for the improvement of the power quality.
{"title":"Stochastic power quality study of distribution supply to metro transit railway","authors":"L. Snider, E. Lo, T. Lai","doi":"10.1109/PESS.2001.970027","DOIUrl":"https://doi.org/10.1109/PESS.2001.970027","url":null,"abstract":"The proliferation of nonlinear loads resulting from new technologies has increased the levels of harmonics in power systems, and traction systems represent large nonlinear loads. This paper presents results of a simulation of the harmonics related to a mass transit railway system. Railway simulation results from the ATP version of Electromagnetic Transient Program (EMTP) with train schedules are presented. Summaries of the parameters affecting the harmonic performance of the traction system and estimates of the most predominant harmonics in a network are also presented and recommendations are made for the improvement of the power quality.","PeriodicalId":273578,"journal":{"name":"2001 Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.01CH37262)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133704404","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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