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Oslo, Norway

Karimi-Ghartemani M.,Mississippi State University | Walseth J.A.,Statnett SF
2012 11th International Conference on Information Science, Signal Processing and their Applications, ISSPA 2012

This paper presents a method for fault analysis in power system which uses the concept of enhanced phase-locked loop (EPLL). The proposed method uses an edge detection strategy to properly re-adjust the system state variables in order to achieve fast and smooth behavior during the initial periods after the inception and/or clearance of a fault. Digital implementation of the algorithm is discussed and simulation results obtained by applying the proposed method to experimental data are presented. © 2012 IEEE. Source

Karimi-Ghartemani M.,Mississippi State University | Mojiri M.,Isfahan University of Technology | Safaee A.,Queens University | Walseth J.A.,Statnett SF | And 3 more authors.
IEEE Transactions on Power Electronics

This paper presents a new three-phase phase-locked loop (PLL) system that primarily estimates the phase angles, frequency, and magnitudes of the a three-phase input signal and also provides a filtered version of the input. It is then extended to the estimation of sequence components, their magnitudes, and phase angles. As compared with the conventional three-phase PLL, this method does not suffer from errors that are caused by signal unbalance and dc offset. It also provides estimate for several other variables which are not included in the conventional three-phase PLL. As compared with the method of using three independent single-phase enhanced PLLs, the proposed method offers a simpler structure. Moreover, the estimated frequency is more accurate and smoother because it uses the information from all three phases to estimate a single value for frequency. The paper also presents a modification that makes the PLL parameters independent from the input signal amplitude. The same modification is applicable to existing methods such as conventional three-phase PLL. Simulation and experimental results are presented to confirm desirable performance of the proposed method. © 2012 IEEE. Source

Seppanen J.M.,Aalto University | Turunen J.,Statnett SF | Koivisto M.,Aalto University | Kishor N.,Aalto University | Haarla L.C.,Aalto University
IEEE Transactions on Power Systems

The analysis of electromechanical oscillatory modes offers essential information on the stability of power systems. This paper investigates the use of the natural excitation technique (NExT) in conjunction with the eigensystem realization algorithm (ERA) for the modal analysis of power systems. The NExT-ERA is a multivariate method utilizing data that are measured from several locations in the power grid. The method is capable of utilizing synchronously measured data from a wide area monitoring system (WAMS) as well as unsynchronized measurements, such as measurements of individual relays' recorders. The performance of the NExT-ERA method is analyzed by applying it to data generated with test systems. The method is also applied to actual measurements received from the Nordic power system. The results indicate that the frequencies and damping ratios of electromechanical oscillatory modes can be analyzed by using the NExT-ERA method. Thus, the method is a promising identification technique for wide-area monitoring of electromechanical oscillations. © 2014 IEEE. Source

Agency: Cordis | Branch: FP7 | Program: CP | Phase: ENERGY.2011.7.2-1 | Award Amount: 19.44M | Year: 2012

6 Transmission System Operators (Belgium, France, Greece, Norway, Portugal and United Kingdom) and CORESO, a TSO coordination centre, together with 13 RTD performers propose a 4 year R&D project to develop and to validate an open interoperable toolbox which will bring support, by 2015, to future operations of the pan-European electricity transmission network, thus favouring increased coordination/harmonisation of operating procedures among network operators. Under the coordination of RTE, new concepts, methods and tools are developed to define security limits of the pan European system and to quantify the distance between an operating point and its nearest security boundary: this requires building its most likely description and developing a risk based security assessment accounting for its dynamic behaviour. The chain of resulting tools meets 3 overarching functional goals: i) to provide a risk based security assessment accounting for uncertainties around the most likely state, for probabilities of contingencies and for corresponding preventive and corrective actions. ii) to construct more realistic states of any system (taking into account its dynamics) over different time frames (real-time, intraday, day ahead, etc.). iii) to assess system security using time domain simulations (with less approximation than when implementing current standard methods/tools). The prototype tool box is validated according to use cases of increasing complexity: static risk-based security approach at control zone level, dynamic security margins accounting for new power technologies (HVDC, PST, FACTS), use of data coming from off-line security screening rules into on-line security assessment, and finally security maps at pan European level. Dissemination is based on periodic workshops for a permanent user group of network operators invited to use modules to meet their own control zone needs and the ones of present or future coordination centres.

Agency: Cordis | Branch: FP7 | Program: MC-IAPP | Phase: FP7-PEOPLE-2009-IAPP | Award Amount: 1.09M | Year: 2010

Power transmission in Europe is entering a period of significant renewal and technological change because the electrical transmission grids face increases in new and variable energy sources, especially from large scale wind power generators. They therefore face future challenges of operation and control. Changes happening in the process industries will also have an impact on electrical supply because electric motors are taking over from traditional gas turbine drivers for large-scale process equipment such as compressors. On the other hand, new measurement and data acquisition methods such as phasor measurement units are allowing greatly improved observation of the transmission grid. In the light of these changes, there is a need for a new action to give Europe a significant lead in methods for enhanced power transmission system operation using emerging measurement technologies. The REAL-SMART proposal presents a balanced programme of applied R-and-D to address measurement-based monitoring and management of the high voltage transmission grid. It involves electrical transmission system operators, companies that supply technologies and components, and universities. The REAL-SMART consortium is interdisciplinary with experts in electrical power systems, modelling, instrumentation, signal analysis, equipment condition monitoring, and automation of oil & gas processes. The consortium will conduct research and undertake secondments to transfer experience and knowledge both ways between Academia and Industry. The project integrates in-depth understanding of the power system operational issues with analysis of state-of-the-art measurements and first-principles physical knowledge. It will invent and develop state-of-the-art tools that will be deployed by the transmission system operators, and will produce trained and experienced personnel. We aim to take a pivotal role in the creation of technology for intelligent operation of the wide-area transmission grids of the future

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