Pub Date : 2007-07-01DOI: 10.1109/PCT.2007.4538457
F. O. Resende, J. Lopes
Large deployment of microgrids will have a considerable impact on the future operation of the electrical networks and will greatly influence the power system dynamics mainly at the Medium Voltage (MV) level whenever the upstream system has been lost. In dynamic studies the whole power system cannot be represented in a detailed manner because the huge system dimension would require a very large computational effort. Therefore dynamic equivalents for microgrids need to be derived. The proposed approach is based on system identification theory for developing dynamic equivalents for microgrids, which are able to retain the relevant dynamics with respect to the existing MV network.
{"title":"Development of Dynamic Equivalents for MicroGrids using System Identification Theory","authors":"F. O. Resende, J. Lopes","doi":"10.1109/PCT.2007.4538457","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538457","url":null,"abstract":"Large deployment of microgrids will have a considerable impact on the future operation of the electrical networks and will greatly influence the power system dynamics mainly at the Medium Voltage (MV) level whenever the upstream system has been lost. In dynamic studies the whole power system cannot be represented in a detailed manner because the huge system dimension would require a very large computational effort. Therefore dynamic equivalents for microgrids need to be derived. The proposed approach is based on system identification theory for developing dynamic equivalents for microgrids, which are able to retain the relevant dynamics with respect to the existing MV network.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"48 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":"132691665","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.2007.4538573
B. Genet, J. Maun
A new monitoring method based on a wide-area network of Phaser Measurement Units (PMU) is proposed. This tool detects on-line and in real-time an incipient voltage instability in the power system. A geographical visualization is introduced to monitor efficiently the state of the network. The method is general and can be implemented in any part of a network prone to voltage instability. It can be used to trigger corrective actions to avoid a collapse. The hypotheses and the results of the new method will be discussed in regard with those given by the Thevenin's equivalent computed at the load bus.
{"title":"Voltage-Stability Monitoring Using Wide-Area Measurement Systems","authors":"B. Genet, J. Maun","doi":"10.1109/PCT.2007.4538573","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538573","url":null,"abstract":"A new monitoring method based on a wide-area network of Phaser Measurement Units (PMU) is proposed. This tool detects on-line and in real-time an incipient voltage instability in the power system. A geographical visualization is introduced to monitor efficiently the state of the network. The method is general and can be implemented in any part of a network prone to voltage instability. It can be used to trigger corrective actions to avoid a collapse. The hypotheses and the results of the new method will be discussed in regard with those given by the Thevenin's equivalent computed at the load bus.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"52 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":"133570606","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.2007.4538571
T. Rauhala, K. Saarinen, P. Vuorenpaa, P. Jarventausta
In May 2006 two Phasor Measurement Units were installed in Finnish 400 kV transmission grid in order to study subsynchronous damping of 950 MVA generating unit located geographically close to 550 MW HVDC transmission system. Subsynchronous damping was analyzed based on post- disturbance data measured using PMU. In this paper the background of the study and the main results from the measurements over period between May 2006 and August 2006 are presented. The quality of measured subsynchronous oscillations is illustrated and the validity of approach on subsynchronous damping estimation is discussed based on the measurements. Also, amplitude of measured subsynchronous components related to different system disturbances are illustrated and the values determined for total subsynchronous damping based on the post-disturbance measurements are presented. Finally, the possibilities to use PMU output data for real-time monitoring of subsynchronous damping is discussed based on the obtained experiences.
{"title":"Determining Subsynchronous Damping Based on PMU Measurements from Finnish 400 kV Transmission Network","authors":"T. Rauhala, K. Saarinen, P. Vuorenpaa, P. Jarventausta","doi":"10.1109/PCT.2007.4538571","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538571","url":null,"abstract":"In May 2006 two Phasor Measurement Units were installed in Finnish 400 kV transmission grid in order to study subsynchronous damping of 950 MVA generating unit located geographically close to 550 MW HVDC transmission system. Subsynchronous damping was analyzed based on post- disturbance data measured using PMU. In this paper the background of the study and the main results from the measurements over period between May 2006 and August 2006 are presented. The quality of measured subsynchronous oscillations is illustrated and the validity of approach on subsynchronous damping estimation is discussed based on the measurements. Also, amplitude of measured subsynchronous components related to different system disturbances are illustrated and the values determined for total subsynchronous damping based on the post-disturbance measurements are presented. Finally, the possibilities to use PMU output data for real-time monitoring of subsynchronous damping is discussed based on the obtained experiences.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"93 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":"117175654","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.2007.4538365
E. Spahić, G. Balzer, A. D. Shakib
The largest disadvantage of wind power is its weather dependence, i.e. volatility. With the fast increase of the installed wind power, especially offshore, their impact on the power system operation will increase too. In order to remedy the impact of these drawbacks of the wind power, the use of batteries as power buffer has been investigated. Smoothening of the power fluctuations from large wind farms and use of batteries as primary and secondary control of the wind farm has been analysed. The connection of one "wind farm - battery" unit on a test power system has been modelled. The system with and without the use of battery has been tested. Thereat the power system stability parameters have been observed (rotor angle, voltage and frequency). Obtained results show large improvement in power system stability when using battery as a power backup of large wind farms.
{"title":"The Impact of the \"Wind Farm - Battery\" Unit on the Power System Stability and Control","authors":"E. Spahić, G. Balzer, A. D. Shakib","doi":"10.1109/PCT.2007.4538365","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538365","url":null,"abstract":"The largest disadvantage of wind power is its weather dependence, i.e. volatility. With the fast increase of the installed wind power, especially offshore, their impact on the power system operation will increase too. In order to remedy the impact of these drawbacks of the wind power, the use of batteries as power buffer has been investigated. Smoothening of the power fluctuations from large wind farms and use of batteries as primary and secondary control of the wind farm has been analysed. The connection of one \"wind farm - battery\" unit on a test power system has been modelled. The system with and without the use of battery has been tested. Thereat the power system stability parameters have been observed (rotor angle, voltage and frequency). Obtained results show large improvement in power system stability when using battery as a power backup of large wind farms.","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":"121989370","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.2007.4538423
G. Bautista, Miguel F. Anjos, Anthony Vannelli
A comparison of Nash-Cournot equilibria using DC and AC approximations of the transmission system is presented in this paper. The goal of doing this comparison is to identify the impact of reactive power and voltage-related issues on Nash equilibria. Following the same rationality of competition and the same solution scheme, a considerable mismatch in outcomes is found. This shows that the use of common linear approximations of the transmission system to model strategic behaviour in electricity markets may produce outcomes that are unlikely to be observed in real markets. Three- and 14-node systems are used to analyze different study cases.
{"title":"Beyond the Use of Linear Approximations for Modelling Nash-Cournot Equilibria","authors":"G. Bautista, Miguel F. Anjos, Anthony Vannelli","doi":"10.1109/PCT.2007.4538423","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538423","url":null,"abstract":"A comparison of Nash-Cournot equilibria using DC and AC approximations of the transmission system is presented in this paper. The goal of doing this comparison is to identify the impact of reactive power and voltage-related issues on Nash equilibria. Following the same rationality of competition and the same solution scheme, a considerable mismatch in outcomes is found. This shows that the use of common linear approximations of the transmission system to model strategic behaviour in electricity markets may produce outcomes that are unlikely to be observed in real markets. Three- and 14-node systems are used to analyze different study cases.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"2 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":"117206413","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.2007.4538601
V. Detfich, P. Skala, Z. Špaček, V. Blazek
The paper presents a new method allowing us to express, in financial terms, the contribution of certain measures undertaken in the network that result in increasing the reliability of electricity supply to customers. This method is based on the potential of reducing the costs of supply interruptions. Simulation tools elaborated by EGU Brno, a. s. which respect the non- homogeneity of the numbers and durations of supply interruptions on individual feeders are used for this purpose. The results obtained follow from the distribution of annual numbers of supply interruptions on feeders and from the distribution of their durations reflecting the real situation on a given group of feeders. The costs of supply interruptions are calculated based on customer's standards of electricity supply continuity. Practical application of the method is demonstrated by using an example of applying a slow auto-reclosing in a 22 kV overhead distribution network and of installing telecontrolled switching elements on a model 22 kV feeder.
本文提出了一种新的方法，使我们能够用财务术语来表示在电网中采取的某些措施对提高客户电力供应可靠性的贡献。这种方法是基于降低供应中断成本的潜力。由EGU Brno, a. s.详细阐述的仿真工具考虑了单个馈线上供电中断的数量和持续时间的非同质性，用于此目的。根据馈线年供电中断次数的分布及其持续时间的分布，得到了反映给定馈线组实际情况的结果。供电中断的成本是根据客户的供电连续性标准来计算的。通过在22kv架空配电网中应用慢速自动重合闸和在22kv馈线上安装遥控开关元件的实例，说明了该方法的实际应用。
{"title":"Evaluation of Measures Undertaken in the Distribution Network Based on the Potential of Reducing the Costs of Supply Interruptions","authors":"V. Detfich, P. Skala, Z. Špaček, V. Blazek","doi":"10.1109/PCT.2007.4538601","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538601","url":null,"abstract":"The paper presents a new method allowing us to express, in financial terms, the contribution of certain measures undertaken in the network that result in increasing the reliability of electricity supply to customers. This method is based on the potential of reducing the costs of supply interruptions. Simulation tools elaborated by EGU Brno, a. s. which respect the non- homogeneity of the numbers and durations of supply interruptions on individual feeders are used for this purpose. The results obtained follow from the distribution of annual numbers of supply interruptions on feeders and from the distribution of their durations reflecting the real situation on a given group of feeders. The costs of supply interruptions are calculated based on customer's standards of electricity supply continuity. Practical application of the method is demonstrated by using an example of applying a slow auto-reclosing in a 22 kV overhead distribution network and of installing telecontrolled switching elements on a model 22 kV feeder.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"41 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":"116606587","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.2007.4538297
I. Kopcak, V.F. da Costa, L. D. da Silva
Continuous advances in the field of power electronics have resulted in new technologies connected to power systems. Examples are the different types of FACTS devices connected to the network to perform a number of control functions or to reinforce congested areas. However, conventional power flow methods are not capable of representing these new components with accuracy. This paper presents a generalized power flow method able to include the steady state characteristics of any dynamic device by using the same models considered for time domain simulation. The proposed method allows the monitoring of the performance of the dynamic devices when certain parameter is changed, such as the load level or the voltage setpoint of a given controller.
{"title":"A Generalized Load Flow Method Including the Steady State Characteristic of Dynamic Devices","authors":"I. Kopcak, V.F. da Costa, L. D. da Silva","doi":"10.1109/PCT.2007.4538297","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538297","url":null,"abstract":"Continuous advances in the field of power electronics have resulted in new technologies connected to power systems. Examples are the different types of FACTS devices connected to the network to perform a number of control functions or to reinforce congested areas. However, conventional power flow methods are not capable of representing these new components with accuracy. This paper presents a generalized power flow method able to include the steady state characteristics of any dynamic device by using the same models considered for time domain simulation. The proposed method allows the monitoring of the performance of the dynamic devices when certain parameter is changed, such as the load level or the voltage setpoint of a given controller.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"273 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":"116623188","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.2007.4538442
N. P. Ziogos, A. C. Tellidou, V. P. Gountis, A. Bakirtzis
This paper presents a Q-Learning algorithm for the development of bidding strategies for market participants in FTR auctions. Each market participant is represented by an autonomous adaptive agent capable of developing its own bidding behavior based on a Q-learning algorithm. Initially, a bi- level optimization problem is formulated. At the first level, a market participant tries to maximize his expected profit under the constraint that, at the second level, an independent system operator tries to maximize the revenues from the FTR auction. It is assumed that each FTR market participant chooses his bidding strategy, for holding a FTR, based on a probabilistic estimate of the LMP differences between withdrawal and injection points. The market participant expected profit is calculated and a Q- learning algorithm is employed to find the optimal bidding strategy. A two-bus and a five-bus test system are used to illustrate the presented method.
{"title":"A Reinforcement Learning Algorithm for Market Participants in FTR Auctions","authors":"N. P. Ziogos, A. C. Tellidou, V. P. Gountis, A. Bakirtzis","doi":"10.1109/PCT.2007.4538442","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538442","url":null,"abstract":"This paper presents a Q-Learning algorithm for the development of bidding strategies for market participants in FTR auctions. Each market participant is represented by an autonomous adaptive agent capable of developing its own bidding behavior based on a Q-learning algorithm. Initially, a bi- level optimization problem is formulated. At the first level, a market participant tries to maximize his expected profit under the constraint that, at the second level, an independent system operator tries to maximize the revenues from the FTR auction. It is assumed that each FTR market participant chooses his bidding strategy, for holding a FTR, based on a probabilistic estimate of the LMP differences between withdrawal and injection points. The market participant expected profit is calculated and a Q- learning algorithm is employed to find the optimal bidding strategy. A two-bus and a five-bus test system are used to illustrate the presented method.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"275 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":"115942766","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.2007.4538547
R. Langella, A. Testa
A new algorithm for energy measurement at positive sequence of fundamental power frequency under unbalanced non-sinusoidal conditions is presented. Extraction of a generalized positive sequence from the three-phase signals in time domain is performed first. Then, an accurate extraction of fundamental power frequency tones is obtained taking advantage of Hanning windowing together with interpolation of the FFT results. Active and reactive power for energy measurements are finally calculated via traditional formulas. Errors due to fundamental power frequency desynchronization are analyzed for the proposed algorithm and for two alternative traditional algorithms. Finally, numerical applications to simple case studies demonstrate the usefulness of the proposed approach and the importance of considering the positive sequence of the fundamental power frequency for a correct billing of the energy supplied to the costumers.
{"title":"A New Algorithm for Energy Measurement at Positive Sequence of Fundamental Power Frequency, Under Unbalanced Non-Sinusoidal Conditions","authors":"R. Langella, A. Testa","doi":"10.1109/PCT.2007.4538547","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538547","url":null,"abstract":"A new algorithm for energy measurement at positive sequence of fundamental power frequency under unbalanced non-sinusoidal conditions is presented. Extraction of a generalized positive sequence from the three-phase signals in time domain is performed first. Then, an accurate extraction of fundamental power frequency tones is obtained taking advantage of Hanning windowing together with interpolation of the FFT results. Active and reactive power for energy measurements are finally calculated via traditional formulas. Errors due to fundamental power frequency desynchronization are analyzed for the proposed algorithm and for two alternative traditional algorithms. Finally, numerical applications to simple case studies demonstrate the usefulness of the proposed approach and the importance of considering the positive sequence of the fundamental power frequency for a correct billing of the energy supplied to the costumers.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"24 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":"116737736","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.2007.4538612
M. Bedriñana, D. Bedoya, Carlos A. Castro
The computation of the maximum loading point (MLP) is crucial to power systems operation and control, There are several methodologies proposed to compute it. The continuation load flow (CLF) is very robust, widely known to draw PV curves, and can be also used for computing the MLP. However it has some drawbacks, the procedure may diverge for some cases and it is very conservative for some networks, taking many iterations. Other efficient technique using nonlinear programming (NLP) has been proposed recently. This method presents clear advantages due to the orientation of the process in direction to the MLP. This paper presents a method based on the CLF and NLP. The idea is to compute the MLP taking some features of the CLF combined with characteristics of NLP. With this combination the MLP can be evaluated with more accuracy and efficiency. Simulations for different systems including IEEE test systems are shown to evaluate the performance of the method. Some comparisons of the methodologies are also shown.
{"title":"Hybrid Method for Calculating the Maximum Loading Point using Continuation Load Flow and Nonlinear Programming Techniques","authors":"M. Bedriñana, D. Bedoya, Carlos A. Castro","doi":"10.1109/PCT.2007.4538612","DOIUrl":"https://doi.org/10.1109/PCT.2007.4538612","url":null,"abstract":"The computation of the maximum loading point (MLP) is crucial to power systems operation and control, There are several methodologies proposed to compute it. The continuation load flow (CLF) is very robust, widely known to draw PV curves, and can be also used for computing the MLP. However it has some drawbacks, the procedure may diverge for some cases and it is very conservative for some networks, taking many iterations. Other efficient technique using nonlinear programming (NLP) has been proposed recently. This method presents clear advantages due to the orientation of the process in direction to the MLP. This paper presents a method based on the CLF and NLP. The idea is to compute the MLP taking some features of the CLF combined with characteristics of NLP. With this combination the MLP can be evaluated with more accuracy and efficiency. Simulations for different systems including IEEE test systems are shown to evaluate the performance of the method. Some comparisons of the methodologies are also shown.","PeriodicalId":356805,"journal":{"name":"2007 IEEE Lausanne Power Tech","volume":"72 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":"121902770","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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