Pub Date : 2007-07-01DOI: 10.1109/PCT.2007.4538500
S. Virmani, D. Vickovic, S. Savulescu
Determination of loadability limits in real-time is essential for the effective and efficient utilization of the power system network particularly in an open access environment. However, determining these limits in real-time in an energy management system (EMS) has been extremely difficult and off-line studies, time consuming simulations, and the operator's knowledge and experience, have been the basis for determining the limits especially when taking into account stability consideration. Therefore, accurate and reliable estimates of the limits in real-time based on the current system state are highly desirable. In this paper, we describe the theoretical basis for an approach that has been successfully installed and proven in several EMS systems. The approach relies on several distinct theoretical concepts: criterion for assessing the steady-state stability limit, the development of a radial equivalent network to which the steady-state stability limit criterion can be applied, a procedure for determining the "distance" of the current operating state from the stability limit (hence finding the available margin of loading), evaluating the effect of contingencies, and determining the "weak" flow gates (links) in the network. Field experience in NOS BiH (ISO Bosnia and Herzegovina) is also presented.
{"title":"Real-Time Calculation of Power System Loadability Limits","authors":"S. Virmani, D. Vickovic, S. Savulescu","doi":"10.1109/PCT.2007.4538500","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538500","url":null,"abstract":"Determination of loadability limits in real-time is essential for the effective and efficient utilization of the power system network particularly in an open access environment. However, determining these limits in real-time in an energy management system (EMS) has been extremely difficult and off-line studies, time consuming simulations, and the operator's knowledge and experience, have been the basis for determining the limits especially when taking into account stability consideration. Therefore, accurate and reliable estimates of the limits in real-time based on the current system state are highly desirable. In this paper, we describe the theoretical basis for an approach that has been successfully installed and proven in several EMS systems. The approach relies on several distinct theoretical concepts: criterion for assessing the steady-state stability limit, the development of a radial equivalent network to which the steady-state stability limit criterion can be applied, a procedure for determining the \"distance\" of the current operating state from the stability limit (hence finding the available margin of loading), evaluating the effect of contingencies, and determining the \"weak\" flow gates (links) in the network. Field experience in NOS BiH (ISO Bosnia and Herzegovina) is also presented.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116763283","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 : 2007-07-01DOI: 10.1109/PCT.2007.4538381
P. Frías, T. Gómez, J. Rivier
The increase of distributed generation (DG) in distribution networks is an important challenge for distribution system operators (DSOs). DG integration not only impacts on DSO short-term costs but also involves new risk uncertainty regarding system reliability, security and network planning. Therefore, because DSO is mainly a regulated business, it is clear that new regulatory mechanisms should be designed. This paper analyzes how the traditional model of DSO regulation is impacted by increasing penetration of DG. A set of proposals on how this model can be improved are presented. Finally, some guidelines on regulatory improvements for the transition between the current and future situation with high penetration of DG are recommended.
{"title":"Regulation of distribution system operators with high penetration of distributed generation","authors":"P. Frías, T. Gómez, J. Rivier","doi":"10.1109/PCT.2007.4538381","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538381","url":null,"abstract":"The increase of distributed generation (DG) in distribution networks is an important challenge for distribution system operators (DSOs). DG integration not only impacts on DSO short-term costs but also involves new risk uncertainty regarding system reliability, security and network planning. Therefore, because DSO is mainly a regulated business, it is clear that new regulatory mechanisms should be designed. This paper analyzes how the traditional model of DSO regulation is impacted by increasing penetration of DG. A set of proposals on how this model can be improved are presented. Finally, some guidelines on regulatory improvements for the transition between the current and future situation with high penetration of DG are recommended.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"15 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120984445","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 : 2007-07-01DOI: 10.1109/PCT.2007.4538517
A. Tuohy, E. Denny, M. O’Malley
As wind power penetration grows, the amount of reserve needed on the system also grows, due to the increases in the uncertainty of wind power, which grows larger as forecast horizon increases. By scheduling the system more often the amount of extra reserve to be carried to cater for wind uncertainty decreases, depending on the flexibility of plant on the system. This reduces the costs of operating the system. There is a trade off between reduced costs due to more frequent commitment, the ability of wind forecasts to be made more accurately, and the increased costs of more flexible plant. This paper examines the benefits of committing the system more frequently, and how different factors such as reliability of the system, accuracy of the forecasts and plant mix impact on this.
{"title":"Rolling Unit Commitment for Systems with Significant Installed Wind Capacity","authors":"A. Tuohy, E. Denny, M. O’Malley","doi":"10.1109/PCT.2007.4538517","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538517","url":null,"abstract":"As wind power penetration grows, the amount of reserve needed on the system also grows, due to the increases in the uncertainty of wind power, which grows larger as forecast horizon increases. By scheduling the system more often the amount of extra reserve to be carried to cater for wind uncertainty decreases, depending on the flexibility of plant on the system. This reduces the costs of operating the system. There is a trade off between reduced costs due to more frequent commitment, the ability of wind forecasts to be made more accurately, and the increased costs of more flexible plant. This paper examines the benefits of committing the system more frequently, and how different factors such as reliability of the system, accuracy of the forecasts and plant mix impact on this.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121019335","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 : 2007-07-01DOI: 10.1109/PCT.2007.4538340
S. Dechanupaprittha, K. Hongesombut, M. Watanabe, Y. Mitani, I. Ngamroo
This paper presents the design of superconducting magnetic energy storage (SMES) controller for improving stabilization of interconnected power system based on synchronized phasor measurement. Load variations with abrupt changes occurring in a power system cause fluctuations of tie-line power flow and significantly disturb the effective use of transmission lines. As one of promising energy storage devices, SMES is applied for power system stabilization. SMES controller is designed based on the wide area synchronized phasor measurement. The estimated model is determined as a coupled vibration model for detection and assessment of an approximated inter-area oscillation mode. Finally, some simulation studies are carried out to demonstrate the applicability and effectiveness of the design method.
{"title":"Design of SMES Controller for Improving Stabilization of Interconnected Power System based on Synchronized Phasor Measurement","authors":"S. Dechanupaprittha, K. Hongesombut, M. Watanabe, Y. Mitani, I. Ngamroo","doi":"10.1109/PCT.2007.4538340","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538340","url":null,"abstract":"This paper presents the design of superconducting magnetic energy storage (SMES) controller for improving stabilization of interconnected power system based on synchronized phasor measurement. Load variations with abrupt changes occurring in a power system cause fluctuations of tie-line power flow and significantly disturb the effective use of transmission lines. As one of promising energy storage devices, SMES is applied for power system stabilization. SMES controller is designed based on the wide area synchronized phasor measurement. The estimated model is determined as a coupled vibration model for detection and assessment of an approximated inter-area oscillation mode. Finally, some simulation studies are carried out to demonstrate the applicability and effectiveness of the design method.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127517521","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 : 2007-07-01DOI: 10.1109/PCT.2007.4538633
C. de Salles, M.L.B. Martinez
This paper presents a mathematical model for distribution transformers winding to simulate its lightning impulse behavior. The aim is to investigate the real source of some signals present in the current wave of lightning impulse test. These signals are generally attached to the testing system and not to the testing transformer. This kind of interpretation can consider approved a failed transformer. The procedure takes into account the comparison between lightning impulse tests on actual transformers and their simulation results. The main contribution of this paper regarding previous publications [1]-[2] is concerning the current wave of chopped impulses. The idea is to use the chopped waves to confirm the existence of small failures on tested transformers that present some of noises in the current wave of full impulses.
{"title":"Model of Distribution Transformers Winding for Lightning","authors":"C. de Salles, M.L.B. Martinez","doi":"10.1109/PCT.2007.4538633","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538633","url":null,"abstract":"This paper presents a mathematical model for distribution transformers winding to simulate its lightning impulse behavior. The aim is to investigate the real source of some signals present in the current wave of lightning impulse test. These signals are generally attached to the testing system and not to the testing transformer. This kind of interpretation can consider approved a failed transformer. The procedure takes into account the comparison between lightning impulse tests on actual transformers and their simulation results. The main contribution of this paper regarding previous publications [1]-[2] is concerning the current wave of chopped impulses. The idea is to use the chopped waves to confirm the existence of small failures on tested transformers that present some of noises in the current wave of full impulses.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124707200","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 : 2007-07-01DOI: 10.1109/PCT.2007.4538630
A. R. Queiroz, F. A. Oliveira, J. Lima, P. Balestrassi
The electricity price has been one of the most important variables since the introduction of deregulation on the electricity sector. On this way, efficient forecasting methods of spot prices have become crucial to maximize the agent benefits. In Brazil the electricity price is based on the marginal cost provided by an optimization software (NEWAVE). Forecasting the operational marginal cost (OMC) and its volatility has been one big problem in the Brazilian market because of the computational time taken by this software. This work presents a fast and efficient model to simulate the OMC using DOE (design of experiments) and ANN (artificial neural networks) techniques. The paper proved that the combined techniques provided a promising result and may be applied to risk management and investment analysis.
{"title":"Simulating Electricity Spot Prices in Brazil Using Neural Network and Design of Experiments","authors":"A. R. Queiroz, F. A. Oliveira, J. Lima, P. Balestrassi","doi":"10.1109/PCT.2007.4538630","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538630","url":null,"abstract":"The electricity price has been one of the most important variables since the introduction of deregulation on the electricity sector. On this way, efficient forecasting methods of spot prices have become crucial to maximize the agent benefits. In Brazil the electricity price is based on the marginal cost provided by an optimization software (NEWAVE). Forecasting the operational marginal cost (OMC) and its volatility has been one big problem in the Brazilian market because of the computational time taken by this software. This work presents a fast and efficient model to simulate the OMC using DOE (design of experiments) and ANN (artificial neural networks) techniques. The paper proved that the combined techniques provided a promising result and may be applied to risk management and investment analysis.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126072542","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 : 2007-07-01DOI: 10.1109/PCT.2007.4538615
A. Campoccia, G. Zizzo
The paper proposes three simple circuit models for the simulation of the behaviour of a global earthing system during different fault events. The models allow one the evaluation of the maximum earth potential rise at every possible fault location and for every possible fault event. The three considered fault events are: single-line-to-earth fault inside a MV/LV substation, double-earth-fault in a MV line, single-line-to-earth fault inside a HV/MV station. After having illustrated the hypotheses at the basis of the study, the circuit models for the three fault events are presented and a numerical example shows how to use them in order to check the "global safety" of the interconnected earthing systems.
{"title":"Simple Circuit Models for Studying Global Earthing Systems","authors":"A. Campoccia, G. Zizzo","doi":"10.1109/PCT.2007.4538615","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538615","url":null,"abstract":"The paper proposes three simple circuit models for the simulation of the behaviour of a global earthing system during different fault events. The models allow one the evaluation of the maximum earth potential rise at every possible fault location and for every possible fault event. The three considered fault events are: single-line-to-earth fault inside a MV/LV substation, double-earth-fault in a MV line, single-line-to-earth fault inside a HV/MV station. After having illustrated the hypotheses at the basis of the study, the circuit models for the three fault events are presented and a numerical example shows how to use them in order to check the \"global safety\" of the interconnected earthing systems.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"606 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123255925","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 : 2007-07-01DOI: 10.1109/PCT.2007.4538443
A. Petoussis, S. G. Petoussis, X.P. Zhang, K. Godfrey
In this paper, the impact of transformer tap-ratio control on the electricity market equilibrium in congested transmission networks is investigated. The analysis is performed using a primal-dual nonlinear interior point algorithm for determining the Nash Supply Function Equilibrium (SFE) of bid-based electricity markets, formulated using ac network model representation. Numerical results demonstrate the effect of tap-ratio control on the bidding strategies of the generating firms for different cases of transmission line congestion conditions, with direct impact on nodal prices and profits. The results show that the impact of the transformer tap-ratio control on the market equilibrium depends on the degree of transmission line congestion in the network.
{"title":"Market Equilibrium in Congested Transmission Networks with Transformer Tap-Ratio Control","authors":"A. Petoussis, S. G. Petoussis, X.P. Zhang, K. Godfrey","doi":"10.1109/PCT.2007.4538443","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538443","url":null,"abstract":"In this paper, the impact of transformer tap-ratio control on the electricity market equilibrium in congested transmission networks is investigated. The analysis is performed using a primal-dual nonlinear interior point algorithm for determining the Nash Supply Function Equilibrium (SFE) of bid-based electricity markets, formulated using ac network model representation. Numerical results demonstrate the effect of tap-ratio control on the bidding strategies of the generating firms for different cases of transmission line congestion conditions, with direct impact on nodal prices and profits. The results show that the impact of the transformer tap-ratio control on the market equilibrium depends on the degree of transmission line congestion in the network.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123390481","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 : 2007-07-01DOI: 10.1109/PCT.2007.4538343
N. Johansson, L. Angquist, H. Nee
This paper describes the design and verification of a time-discrete adaptive controller for damping of inter-area power oscillations, power flow control, and transient stability improvement. Only locally measured signals are used as inputs to the controller. The controller may be used with any FACTS device which operates as a variable series reactance in the power grid, such as for example the TCSC. The controller is based on a reduced system model which relies on the assumption of one dominating inter-area oscillation mode in the power system where the FACTS device is placed. Verification of the controller is performed by means of digital simulations of a four-machine system commonly used to study inter-area oscillations.
{"title":"Adaptive Control of Controlled Series Compensators for Power System Stability Improvement","authors":"N. Johansson, L. Angquist, H. Nee","doi":"10.1109/PCT.2007.4538343","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538343","url":null,"abstract":"This paper describes the design and verification of a time-discrete adaptive controller for damping of inter-area power oscillations, power flow control, and transient stability improvement. Only locally measured signals are used as inputs to the controller. The controller may be used with any FACTS device which operates as a variable series reactance in the power grid, such as for example the TCSC. The controller is based on a reduced system model which relies on the assumption of one dominating inter-area oscillation mode in the power system where the FACTS device is placed. Verification of the controller is performed by means of digital simulations of a four-machine system commonly used to study inter-area oscillations.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125347468","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 : 2007-07-01DOI: 10.1109/PCT.2007.4538375
B.C. Paucar, J. Ortiz, K. S. Collazos, L. Leite, J. Pinto
This work presents the simulation of a maximum voltage estimator and control system to maintain the photovoltaic (PV) generator in the maximum power point, independent of load variations. A fuzzy logic systems (FLS) is implzemented, to estimate, from radiation and temperature data, the maximum voltage of operation of PV generator. The charge and discharge of the battery and the SOC battery are controlled with a radial basis function neural network (RBF-NN).
{"title":"Power Operation Optimization of Photovoltaic Stand Alone System with Variable Loads Using Fuzzy Voltage Estimator and Neural Network Controller","authors":"B.C. Paucar, J. Ortiz, K. S. Collazos, L. Leite, J. Pinto","doi":"10.1109/PCT.2007.4538375","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538375","url":null,"abstract":"This work presents the simulation of a maximum voltage estimator and control system to maintain the photovoltaic (PV) generator in the maximum power point, independent of load variations. A fuzzy logic systems (FLS) is implzemented, to estimate, from radiation and temperature data, the maximum voltage of operation of PV generator. The charge and discharge of the battery and the SOC battery are controlled with a radial basis function neural network (RBF-NN).","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126953357","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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