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RUDEŽ, U., MIHALIČ, R.
POSSIBILITIES FOR UPDATING UNDERFREQUENCY LOAD SHEDDING PROTECTION IN THE SLOVENIAN POWER SYSTEM
KOMUNALNA ENERGETIKA / POWER ENGINERING, 19
In recent decades, the advantages of a fast development in the communication and computer technology have been successfully harvested in the majority of technological areas for updating various mechanisms and processes. Power system control and protection is no exception. However, in certain other countries actual implementation of modern technologies into power system control and protection mechanisms takes less time compared to Slovenia. In case of a sudden major generation unit outage severe underfrequency conditions appear in the power system and only a centralized gathering of measurements and global actions (e.g. use of WAMS and GPS technology) can represent an appropriate approach to a global problem. In such circumstances, underfrequency load shedding is in many times the last resort tool for avoiding a total power system blackout. Consequently, its appropriate actions are of great importance both from technological and economical point of view. As a current status of an underfrequency load shedding protection in the Slovenian power system is still on the traditional level, in this paper authors summarize some of known developed mechanisms, among which some of them might be considered as an actual possibility for an upgrade of current underfrequency scheme in the Slovenian power system to an adaptive level.
VORŠIČ, J., VOH, J.
POWER SYSTEMS PROBABILITY CALCULATIONS SOFTWARE DEVELOPMENT
KOMUNALNA ENERGETIKA / POWER ENGINERING, 22
Method for planning and operation of power system which considers changes of operational conditions is described in this work. Input parameters - node loads in the load flow probability calculation are passed as probability function resulting from former operation careful analysis.
Based on described method calculation software has been developed. Node voltages, load flows, element currents and losses are calculated from node loads random vector considering connectedness among working and reactive power of same and adjoining nodes. Results (node voltages, load flows, currents and losses) are shown with expected value (arithmetical mean value) and mean square deviation in tabulated form. At the same time elements (lines, transformers) load control according to the natural (lines) and thermic power has been performed. Load flow histograms are real value of this method.
KLASINC, D.
REGULATIONS IN ELECTRIC POWER SYSTEMS
KOMUNALNA ENERGETIKA / POWER ENGINERING, 25
This paper represents regulations used in electric power systems. It describes operating modes of the primary, secondary and tertiary regulation in the electrical power network. This paper will describe operations of turbine governors and their impact on the electric power system. An example of network collapse including the chain of hydro power plants, as well as response of turbine governors will be presented.
RUDEŽ, U., MIHALIČ, R.
Impact of Considered SVC Implementation in the Slovenian Power System on Inter-Area ENTSO-E Oscillation Damping
KOMUNALNA ENERGETIKA / POWER ENGINERING, 191
During the planning process of possible future investments into the Slovenian power system, a need arose for the comprehensive analysis related to low-frequency inter-area oscillation damping of a static var compensator (SVC) device. The SVC device was initially considered for solving local steady-state voltage issues on highest 220 kV and 400 kV voltage levels in the region. As the SVC device features fast dynamic response, it seemed reasonable to verify whether its implementation benefits the operation of the entire ENTSO-E interconnection as well. The presented analysis was performed using a complex model for dynamic studies, comprising publicly available ENTSO-E model and internally constructed Slovenian power-system model, which was successfully tested and verified in the past. Modelling of the SVC device was achieved by means of available research publications dealing with the subject, both foreign as well as domestic. By implementing a simple damping strategy, the results showed a positive effect on a small-signal stability and indicated which inter-area oscillations can be successfully damped when considered devices are connected to the Slovenian high-voltage transmission network.
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