427 research outputs found
IEC 61850 tripping circuit monitor with IEEE 1588 synchronization
No full textY. Liu, R. Zivanovic and S. Al-Saraw
Nonparametric time-varying phasor estimation in power systems by using a non-quadratic criterium
No full textIn this paper, we present an application of the robust nonparametric signal modelling technique for tracking the frequency and time-varying phasor of voltage! or current in power systems. A linear function is used to approximate these signals locally on a sliding window of variable length. A non-quadratic criterion instead. of a weighted least squares criterion will be used to fit the linear function to the data. The paper concludes with the presentation of the representative testing results.Jordaan, J.A.; Zivanovic, R
Automatic signal segmentation based on abrupt change detection for power systems applications
No full textCopyright © 2006 IEEEDetection of abrupt changes in the signal parameters can be used to segment the signal. This has been particularly useful in automatic disturbance recognition in power systems, where the signals are first segmented event-specifically and processed subsequently to recognize and analyze the disturbances. This paper describes several abrupt change detection-based segmentation algorithms and their applications in the power systems. The applications include automatic disturbance recognition, synchronization, relay performance analysis etc, where recorded signals from the power network in South Africa have been used.Ukil, A.; Zivanovic, R
Pre-filtering improves Prony analysis of disturbance records
No full text© 2004 Institution of Engineering and TechnologyProny analysis provides resolution of closely spaced multiple modes in signals with high signal to noise ratio. Results are not satisfactory for practical noisy signals recorded during power system disturbances. Attenuation of estimated parameters is the outcome in the case of low signal to noise ratio. This paper presents the application of the smoothing filter for pre-processing signals before using Prony's method. This technique is tested on real power system examples.R. Zivanovic and P. Schegne
Dynamic leapfrog algorithm for power system estimation
No full textCopyright © 2003 IEEPower system state estimation is a very large-scale, sparse and non-linear problem. The following methods to solve the problem will be tested and compared: Gauss-Newton and the Dynamic Leapfrog method. The IEEE 14-bus power system is used to compare the different solvers. Cases when Gauss-Newton does not converge are identified. The Dynamic leapfrog method is proposed to be used in state estimation to solve these non-convergent cases. For this small-scale power system the dynamic method proves to be numerically robust compared to Gauss-Newton.Jordan, J. A. and Zivanovic,
Developing a model to silmulate least economic cost evaluation of transmission expanison investment
No full textTransmission planning can broadly be categorized into deterministic and probabilistic reliability planning. The probabilistic approach is often preferred as it aims to reduce transmission supply costs, by sharing risk between the customer and the utility. This is done by determining the least economic cost (LEC) between the customer interruption cost (CIC) and capital investment required to improve the network reliability. However performing a LEC evaluation requires substantially more variables than deterministic evaluation. This paper analyses the LEC methodology and develops a simulation model to perform probabilistic least economic cost evaluations. © Copyright KTH 2006.Marais, Ronald ; Estment, Roy ; Zivanovic, Rastk
Enhanced segmentation of disturbance records by adaptive thresholding
No full textTo analyse power system fault events captured by disturbance recorders the sampled analogue waveforms (voltages and currents) have to be segmented into system states (pre-fault, fault,...). In this paper a combination of wavelet transform (WT) and linear prediction coding (LPC) is applied to the symmetrical space phasor signals of the voltage and current waveforms. The signals obtained contain impulses when the system state changes abruptly. A threshold for segmentation is calculated using median filtering with adaptive window length. The segment borders are finally merged and validated.Stachel Philipp, Schegner Peter and Zivanovic, Rastko;http://www.pscc2008.org
An IEC 61850 synchronised event logger for substation topology processing
No full textSubstation automation systems consist of intelligent electronic devices (IEDs), substation computers, and the communication network between them for implementing control, protection and monitoring tasks in substations. This paper presents a topology processing technique that uses substation event information captured from legacy IEDs using a logging device. Such a device accurately translates the IEDs' process-level control signals into a binary data representation using non-intrusive current transducers. The data is then transmitted using Generic Object Oriented Substation Event message format, which is defined in the latest substation communication standard IEC 61850. The device also implements IEEE 1588 standard to provide synchronised time-stamp values for each translated binary data within sub-microsecond accuracy. The event data obtained by using the logger on legacy IEDs is combined with data obtained directly from IEC 61850 compliant IEDs in processing the real-time substation topology. The proposed system could overcome existing problems of supervisory control and data acquisition systems, such as inaccurate timing information of substation events and unreliable topology processing in presence of bad data. Preliminary test results that demonstrate the operation of the new system are presented in the paper.Liu Y., Zivanovic R. and Al-Sarawi S
Agent technology used in power systems
No full textAgents are believed to be an important new way of conceptualizing and implementing certain types of software applications. This work will give an overview of how intelligent agent technology can be used in power systems and power application software. At first, agent technology is briefly introduced. Thereafter, the use of agent technology is proposed for power system state estimation, database environments and demand management. The paper ends with a conclusion and recommendations for future work.Ralf Biernatzki, Berthold Bitzer, Rastko Zivanovic, Andries Els, Stephan El
A Synchronized event logger for substation topology processing
No full textWe present a topology processing technique for substations. The proposed technique synchronizes substation event information using a logging system, overcoming existing problems of SCADA systems, such as inaccurate timing information of substation events and unreliable topology processing in presence of bad data. The design of the proposed event logging system and its application are also presented.Yang Liu, Rastko Zivanovic, Said Al-Sarawi Cristian Marinescu and Richard Cochra
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