U clanku su opisane specificnosti o kojima treba voditi racuna prilikom revitalizacije relejne za... more U clanku su opisane specificnosti o kojima treba voditi racuna prilikom revitalizacije relejne zastite u prijenosnoj mreži, elektranama i distribuciji. Uz zahtjeve na relejnu zastitu u prijenosnom mrežama opisani su zahtjevi koje moderna numericka relejna zastita postavlja na telekomunikacijski sustav. Uz zahtjeve na relejnu zastitu u elektranama dan je prijedlog funkcija relejne zastite za veliki i mali generator. Uz relejnu zastitu u srednjenaponskim mrežama dane su potrebne funkcije relejne zastite za određene tipove polja.
ABSTRACT The paper presents an evaluation of the ATP-EMTP in power system protection. A simulatio... more ABSTRACT The paper presents an evaluation of the ATP-EMTP in power system protection. A simulation model of an actual power plant and substation were created and short circuits were simulated. The analysis of results is given and compared with actual results of the real measurements
This paper addresses the challenges of developing a modern power system laboratory at the Faculty... more This paper addresses the challenges of developing a modern power system laboratory at the Faculty of Electrical Engineering and Computing, University of Zagreb. Focused on problem-based learning, the laboratory, developed together by professors and students, is a key to practical teaching of power system design, analysis and control.
This paper analyses the fundamental principles of distance protection relays while highlighting t... more This paper analyses the fundamental principles of distance protection relays while highlighting the importance of correct relay parameterising through a set of relay tests. Numerical distance relays can have up to 6 distance zones, and nowadays most of them have a quadrilateral (polygonal) characteristic. The specific objective of this study was to apply those principles on a SIPROTEC distance protection 7SA611 relay with the help of Omicron CMC 56 testing device, as well as to describe the testing process. As a part of the testing, DIGSI and Test Universe Software were used. Experimental results confirm the theoretical principles of distance protection and show the advantages of numerical relays. This paper concludes that optimal choice of reach settings and time delays between the zones, as well as zone directions, can significantly impact the selectivity of the protection system, and therefore the scope and time of the outage.
The method used for neutral point grounding is very important for power network operation. There ... more The method used for neutral point grounding is very important for power network operation. There are many ways of grounding, which are used in practice, and the decision on the method of neutral grounding depends on the situation in the network connected to the substation. When deciding on the method of neutral grounding it is necessary to thoroughly consider all the advantages and disadvantages of individual modes of neutral grounding, and then choose the best technical and economical solution. This paper analyzes the ways of neutral point grounding in medium voltage networks used in the current practice in Croatia which are isolated neutral point, low resistance earthing, partial compensation and resonant earthing. The use of shunt circuit-breaker is also described. Additionally, a survey of the relays used for the neutral point grounding system inside the substations was conducted and a brief analysis of the results is presented in the paper.
2017 25th Mediterranean Conference on Control and Automation (MED), 2017
Due to the increasing low capacity distributed generators (DGs) installations and penalization of... more Due to the increasing low capacity distributed generators (DGs) installations and penalization of supply disruptions in electrical distribution grid, it is necessary to invest in the distribution protection system. This paper discusses profitability of installation of relays with distance protection function that could protect lines of different voltage levels, lengths and other relevant attributes. The aim is to determine which lines are worth protecting with distance protection and according to that, order of investment by multi-criteria decisionmaking method — analytic hierarchic process (AHP). The first part is an introduction where the circumstances, potential benefits and problems that may arise in distribution grids are presented. This is followed by theory of distance protection and analytic hierarchy process. The final part describes the criteria that should be considered and the way of applying the AHP method with a real example from Croatian distribution grid.
The article presents model for development of realistic operation chart, i.e. P-Q diagram, at poi... more The article presents model for development of realistic operation chart, i.e. P-Q diagram, at point of common coupling of photovoltaic power plant, comprised of multiple inverter units, connected to medium voltage grid. Structure and components of common multi-inverter photovoltaic power plant connected to medium voltage is analyzed. Contributions of all plant components to total active and reactive power are theoretically determined. On base of that analysis P-Q diagram of all possible plant operation points at the point of common coupling is defined. Measurements conducted on real case study plant are used for comparison with calculated values and for necessary corrections to the model. Keywords— inverter, medium voltage, operation chart, photovoltaic plant, P-Q diagram
Toplinski sektor je vrlo važan za funkcioniranje modernog drustva, te je potrebno sustavno i orga... more Toplinski sektor je vrlo važan za funkcioniranje modernog drustva, te je potrebno sustavno i organizirano poslovanje i razvoj sektora hrvatskog toplinarstva. Svrha ove studije je provesti analizu potrebnih energetskih, tehnickih, ekonomskih i pravnih podloga.
The method used for neutral point grounding is very important for power network operation. There ... more The method used for neutral point grounding is very important for power network operation. There are many ways of grounding, which are used in practice, and the decision on the method of neutral grounding depends on the situation in the network connected to the substation. When deciding on the method of neutral grounding it is necessary to thoroughly consider all the advantages and disadvantages of individual modes of neutral grounding, and then choose the best technical and economical solution.
The proposed hybrid state estimator calculates pseudo-injections from the voltage and current pha... more The proposed hybrid state estimator calculates pseudo-injections from the voltage and current phasors collected by Phasor Measurement Units (PMUs). The pseudo-injections are combined with the voltage phasors and conventional measurements as inputs for the iterative algorithm with addition of equality constraints for zero-injections. The methodology is tested on the IEEE test systems with 14, 30, 57 and 118 buses as well as on the Croatian transmission power system and compared to the classical solution that uses conventional measurements only. Streszczenie. Zaproponowano hybrydowy estymator stanu obliczający pseudo-injekcje z napiecia i prądu fazora. Metode przetestowano w systemie IEEE z rozną liczbą szyn a takze w chorwackim systemie energetycznym. (Hybrydowy wymuszony estymator stanu wz pomiarem pseudo- injekcji)
U clanku su opisane specificnosti o kojima treba voditi racuna prilikom revitalizacije relejne za... more U clanku su opisane specificnosti o kojima treba voditi racuna prilikom revitalizacije relejne zastite u prijenosnoj mreži, elektranama i distribuciji. Uz zahtjeve na relejnu zastitu u prijenosnom mrežama opisani su zahtjevi koje moderna numericka relejna zastita postavlja na telekomunikacijski sustav. Uz zahtjeve na relejnu zastitu u elektranama dan je prijedlog funkcija relejne zastite za veliki i mali generator. Uz relejnu zastitu u srednjenaponskim mrežama dane su potrebne funkcije relejne zastite za određene tipove polja.
ABSTRACT The paper presents an evaluation of the ATP-EMTP in power system protection. A simulatio... more ABSTRACT The paper presents an evaluation of the ATP-EMTP in power system protection. A simulation model of an actual power plant and substation were created and short circuits were simulated. The analysis of results is given and compared with actual results of the real measurements
This paper addresses the challenges of developing a modern power system laboratory at the Faculty... more This paper addresses the challenges of developing a modern power system laboratory at the Faculty of Electrical Engineering and Computing, University of Zagreb. Focused on problem-based learning, the laboratory, developed together by professors and students, is a key to practical teaching of power system design, analysis and control.
This paper analyses the fundamental principles of distance protection relays while highlighting t... more This paper analyses the fundamental principles of distance protection relays while highlighting the importance of correct relay parameterising through a set of relay tests. Numerical distance relays can have up to 6 distance zones, and nowadays most of them have a quadrilateral (polygonal) characteristic. The specific objective of this study was to apply those principles on a SIPROTEC distance protection 7SA611 relay with the help of Omicron CMC 56 testing device, as well as to describe the testing process. As a part of the testing, DIGSI and Test Universe Software were used. Experimental results confirm the theoretical principles of distance protection and show the advantages of numerical relays. This paper concludes that optimal choice of reach settings and time delays between the zones, as well as zone directions, can significantly impact the selectivity of the protection system, and therefore the scope and time of the outage.
The method used for neutral point grounding is very important for power network operation. There ... more The method used for neutral point grounding is very important for power network operation. There are many ways of grounding, which are used in practice, and the decision on the method of neutral grounding depends on the situation in the network connected to the substation. When deciding on the method of neutral grounding it is necessary to thoroughly consider all the advantages and disadvantages of individual modes of neutral grounding, and then choose the best technical and economical solution. This paper analyzes the ways of neutral point grounding in medium voltage networks used in the current practice in Croatia which are isolated neutral point, low resistance earthing, partial compensation and resonant earthing. The use of shunt circuit-breaker is also described. Additionally, a survey of the relays used for the neutral point grounding system inside the substations was conducted and a brief analysis of the results is presented in the paper.
2017 25th Mediterranean Conference on Control and Automation (MED), 2017
Due to the increasing low capacity distributed generators (DGs) installations and penalization of... more Due to the increasing low capacity distributed generators (DGs) installations and penalization of supply disruptions in electrical distribution grid, it is necessary to invest in the distribution protection system. This paper discusses profitability of installation of relays with distance protection function that could protect lines of different voltage levels, lengths and other relevant attributes. The aim is to determine which lines are worth protecting with distance protection and according to that, order of investment by multi-criteria decisionmaking method — analytic hierarchic process (AHP). The first part is an introduction where the circumstances, potential benefits and problems that may arise in distribution grids are presented. This is followed by theory of distance protection and analytic hierarchy process. The final part describes the criteria that should be considered and the way of applying the AHP method with a real example from Croatian distribution grid.
The article presents model for development of realistic operation chart, i.e. P-Q diagram, at poi... more The article presents model for development of realistic operation chart, i.e. P-Q diagram, at point of common coupling of photovoltaic power plant, comprised of multiple inverter units, connected to medium voltage grid. Structure and components of common multi-inverter photovoltaic power plant connected to medium voltage is analyzed. Contributions of all plant components to total active and reactive power are theoretically determined. On base of that analysis P-Q diagram of all possible plant operation points at the point of common coupling is defined. Measurements conducted on real case study plant are used for comparison with calculated values and for necessary corrections to the model. Keywords— inverter, medium voltage, operation chart, photovoltaic plant, P-Q diagram
Toplinski sektor je vrlo važan za funkcioniranje modernog drustva, te je potrebno sustavno i orga... more Toplinski sektor je vrlo važan za funkcioniranje modernog drustva, te je potrebno sustavno i organizirano poslovanje i razvoj sektora hrvatskog toplinarstva. Svrha ove studije je provesti analizu potrebnih energetskih, tehnickih, ekonomskih i pravnih podloga.
The method used for neutral point grounding is very important for power network operation. There ... more The method used for neutral point grounding is very important for power network operation. There are many ways of grounding, which are used in practice, and the decision on the method of neutral grounding depends on the situation in the network connected to the substation. When deciding on the method of neutral grounding it is necessary to thoroughly consider all the advantages and disadvantages of individual modes of neutral grounding, and then choose the best technical and economical solution.
The proposed hybrid state estimator calculates pseudo-injections from the voltage and current pha... more The proposed hybrid state estimator calculates pseudo-injections from the voltage and current phasors collected by Phasor Measurement Units (PMUs). The pseudo-injections are combined with the voltage phasors and conventional measurements as inputs for the iterative algorithm with addition of equality constraints for zero-injections. The methodology is tested on the IEEE test systems with 14, 30, 57 and 118 buses as well as on the Croatian transmission power system and compared to the classical solution that uses conventional measurements only. Streszczenie. Zaproponowano hybrydowy estymator stanu obliczający pseudo-injekcje z napiecia i prądu fazora. Metode przetestowano w systemie IEEE z rozną liczbą szyn a takze w chorwackim systemie energetycznym. (Hybrydowy wymuszony estymator stanu wz pomiarem pseudo- injekcji)
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