Milan Vidmar Electric Power Research Institute

This paper identifies and describes the damages to underground power cables and cable sheaths caused by atmospheric discharges in their vicinity. Based on field experience the process of damage formation and the impact on this process of different geological and atmospheric conditions is given. It outlines the correlation between the distance of the affected cable and the lightning strike as well other electrical, chemical and mechanical elements which deteriorate the cable dielectric strength to avoid electrical breakdown of the cable. An analysis has been drawn up of lightning flash density along the underground power cable corridor, the electrical current parameters and the degree of exposure of underground power cables, using the lightning location system SCALAR. The influence of nearby buildings and protective elements during a lightning strike on the distribution of the electric potential near the underground power cable is also presented. The risk assessment regarding the importance of part of the electrical network is discussed, as well as the aspect of repetitions and the size of the amplitude of the lightning current. Finally, protective measures against lightning strike are analysed and recommendations are given for additional underground power cables protection in areas with high lightning flash density.

7. mednarodna konferenca o tehnologijah in poslovnih modelih za krožno gospodarstvo: zbornik konference. Fakulteta za kemijo in kemijsko tehnologijo Univerze v Mariboru je v sodelovanju s Strateško razvojno-inovacijskim partnerstvom – Mreže za prehod v krožno gospodarstvo (SRIP – Krožno gospodarstvo), s katerim upravlja Štajerska gospodarska zbornica, organizirala 7. mednarodno znanstvenoraziskovalno, strokovno in razvojno konferenco Tehnologije in poslovni modeli za krožno gospodarstvo (Technologies & Business Models for Circular Economy; TBMCE), ki je potekala od 4. do 6. septembra 2024 v Grand hotelu Bernardin. Teme TBMCE 2024 so zajemale aktualna vprašanja tehnološkega razvoja in odgovornosti družbe na njeni razvojni poti k bolj odgovornemu, krožnemu ravnanju z viri. Konferenčni program je vključeval okroglo mizo z naslovom Prehod v krožno gospodarstvo v Jugovzhodni Evropi, 5 panelnih diskusij, plenarno in 2 uvodni predavanji, ustna predavanja in predstavitve v obliki posterjev. Dogodek je potekal pod pokroviteljstvom Ministrstva za gospodarstvo, turizem in šport in Ministrstva za kohezijo in regionalni razvoj. Kot soorganizatorji so se nam pridružili EIT RawMaterials RIS središča Adria in SPIRIT Slovenija ter Pomurski tehnološki park v sklopu projektov GREENE 4.0 in CI-Hub.

Abstract Nuclear emergencies confront decision‐makers, emergency actors and publics with several challenges, many of which are related to social, ethical and communication aspects. Based on empirical data from three European countries, this paper investigates citizens' potential behaviour in an emergency situation. It analyses relationships between self‐assessed compliance with protective actions and a number of variables, including knowledge about protective actions, trustworthiness of communicators, perceived social norm (expectation of other residents' behaviour), perceived effectiveness and perceived difficulty of protective actions. Results suggest that most respondents expect to follow actions advised by authorities, except for leaving children at school or avoiding the use of phones. Moreover, large fractions of local and wider publics may seek to avoid risks by rejecting food produced in affected areas even when it satisfies legal norms or taking iodine tablets when not needed. Self‐assessed compliance with protective actions is positively correlated with perceived social norm, perceived effectiveness and compliance with other actions; and negatively correlated with perceived difficulty. Higher trust in the regulator is associated with higher compliance with some actions, but mostly among the local populations. We argue that clarifying and anticipating societal concerns contributes to enhancing societal resilience and the response to nuclear accidents.

This paper reports on the research of mental models of uncertainties management in an emergency situation which was carried out in the framework of the European CONFIDENCE (COping with uNcertainties For Improved modelling and DEcision making in Nuclear emergenCiEs) Project. The methodology included the mapping of mental models among several emergency preparedness and response experts and then performing interviews based on structured protocol with lay people in five countries: Germany, Greece, Slovak Republic, Slovenia and Spain. The aim of these investigations was to trace the concepts and understandings of emergency preparedness and response and to identify possible gaps between experts and lay people. The article presents the main results of this research and suggestions for the improvement of EP & R planning.

The power electronic equipment contribution to the harmonic distortion levels at the connection point to the transmission system shall not exceed the limits specified by the network operator in the tender. The maximum acceptable STATCOM harmonic content was set based on the planned levels of harmonic distortions in the HV and EHV transmission systems and determined by methodologies for evaluating the emission level limits, both according to the IEC 61000-3-6 standard. The limitations are defined in the range from the 2nd to the 50th harmonics. These voltage emission levels are set relatively low, thus requiring accurate measurements to evaluate the level. The paper deals with the opportunities for measuring/verifying the attained distortion level. For this purpose, the complete methodology for testing must be established. At the first stage the voltage must be transformed from 400 kV to the level which is suitable to carry out measurements with the appropriate accuracy for all frequencies of interest. As it is well known the frequency characteristics of conventional voltage instrument transformers are not always appropriate. They are primarily designed for 50 Hz network frequency. For that reason, various approaches were studied. To construct a capacitive voltage divider the transformer bushing with its capacitance and measuring terminals was considered. Besides capacitance on the LV side additional special circuit was assembled to allow a reliable transmission of the signal to the recorder input. Special attention was put on circuit EM interference resistance. In the HV laboratory the comparison of frequency response of capacitive (bushing) voltage divider and conventional inductive voltage instrument transformer vs. reference laboratory divider was performed to test voltage ratio accuracy as a frequency parameter. Since ratio inaccuracy appears as a systematic error the possibility of frequency dependent calibration was studied. At the receiving end the voltage was digitized using an appropriate A/D converter with enough amplitude resolution and sample rate. In the next step spectrum analysis of the signal was performed. Special measures were taken to avoid high-frequency aliasing error. A testing software package was prepared which basically utilizes spectral analyses (discrete frequency value, THD estimation), frequency characteristics comparison, graphical presentation, data storing and all the necessary mathematical tools. The last task was to design the suitable test setup and to prepare an adequate procedure applicable to perform voltage harmonic content measurements on STATCOM device as well as transient over-voltages in the field.

this paper aims to report primarily on new measures encompassed and introduced with respect to the relevant technical regulations put recently in force and on endeavors in immediate mostly technical modifications of assets imposed by lessons learned during past emergency events, as well. Emphasis was given particularly to enforcing of asset’s mechanical withstand capability based on scrutinized analyses of loads experienced during past emergency events. Increasing withstand of critical structures was selectively made. This paper gives an overview of various essential long-term activities and shows the level of new developments achieved after encountering bitter experiences during last decade. The paper deals also with assessing loading limits of selected essential network components aiming to reduce system vulnerability during emergencies hence increase its resilience. Majority of the experienced emergencies were produced by harsh weather impacts in the wintertime. There were many cases of OHL failures, which triggered in the aftermath scrutinized analyses aiming to determine the mechanical loads, encountered. Suitable refurbishing of OHL critical parts have been done respecting new standards. Aiming to allow for expedite restoring of OHL operating capability in emergencies the introduction of Emergency (modular) towers usage was selected and successfully implemented. Owing to the notorious fact, that OHLs’ and power transformer’s loading limits can be extended, several projects were launched to assess, evaluate and eventually up-grade the limit capacity implementing advanced monitoring equipment. Intensive support to asset management was done, such as maintenance optimization, state-of-the-art approach, condition monitoring of HV equipment, assets life cycle assessment and evaluation, etc. One of all-important steady processes remains to encourage the political decision makers to support the erection of new facilities notably OHL through simplifying and facilitating the spatial planning procedure (OHLs Right of Ways!) as well as mediating the social public-private dialogue. All these endeavors being in favor of upgrading the power system resilience.

The paper proposes and discusses algorithms to improve the estimation of the impedance components of the electrical systems under the non-coherent sampling conditions in the frequency domain without knowing the frequency of the investigated component. It has been pointed out that estimation with summation of two quotients with successive amplitude DFT coefficients very reduce the systematic error contribution in the vicinities of the integer coherent sampling conditions. Using the Hann window, as compromise between main-lobe width and leakage suppression in the short measurement time, and the two largest local amplitude DFT coefficients gives lower systematic errors in the summation of two quotients approach than in the quotient of two summations approach.

An approach of assessing the annual air quality impact of industrial sources from results of simulations performed for characteristic days, representative for different local scale dispersion conditions, is being studied. The methodology for selecting the characteristic days is presented. For classifications with different number of similar day clusters the air-quality directive limit and target values for SO 2 are calculated from CALMET/CALPUFF model simulations performed for representative days. These results are compared with target and limit values assessed from results of simulations performed over the entire one year time period. Results show that especially the annual average and hourly maximum fields can be assessed from characteristic days, but it cannot be assured that certain classification with selected characteristic days will provide accurate results.

Paper describes technical and economical proceedings for optimal dispersed generation network connection point determination. Different measures for rising of fault current ratings at connection point are presented: connection point shifting, network cabling, transformer upgrading, and connection of DG to separate bus. Technical and economical point of view of different DG connection solutions is presented. (4 pages)