Vladica Mijailovic - Academia.edu (original) (raw)

Papers by Vladica Mijailovic

Abstract: The paper presents the dynamic model of maintenance costs of the power transformer func... more Abstract: The paper presents the dynamic model of maintenance costs of the power transformer functional components. Reliability is modeled combining the exponential and Weibull's distribution. The simulation was performed with the aim of corrective maintenance and installation of the continuous monitoring system of the most critical components. Simulation Dynamic System (SDS) method and VENSIM PLE software was used to simulate the cost. In this way, significant savings in maintenance costs will be achieved with a small initial investment.

Sensors and Actuators A: Physical

Abstract This paper introduces new electronic sensor circuits based on the usage of a piezoelectr... more Abstract This paper introduces new electronic sensor circuits based on the usage of a piezoelectric Polyvinylidene fluoride-PVDF pressure detector coupled with a current-mode instrumentation amplifier, Schmitt comparator, and only grounded resistors. Pressure/force is measured in terms of the charge generated by the PVDF element as a result of the direct piezoelectric effect. The experimental test results demonstrated that the dynamic pressure response, the sensitivity and linearity of the designed sensor were higher than the sensitivity and linearity of a traditional piezoelectric sensor. The sensitivity of the PVDF sensor was 0.08 mV/Pa. The detector is calibrated over a frequency range of 1 Hz–1 kHz. The proposed signal conditioning electronics offer a potential for future miniaturization in order to be integrated with different commercial devices, for detecting certain tiny activities including finger movements, robotics and smart electronic devices.

The paper suggests a method for effects evaluation of a few activities and measures, undertaken a... more The paper suggests a method for effects evaluation of a few activities and measures, undertaken as a part of preventive maintenance of power transformers. The method enables calculation of expected failures repair cost and load curtailment cost. The method identifies minor and major failures. Power transformer is a complex system, consisting of five components (functional parts). It is assumed that each component has two independent, competing failure modes: wear-out failure mode, modeled by two-parameter Weibull distribution, and a chance failure mode, characterized by an exponential distribution. The application of the method is demonstrated for one transformer station (TS) 110/x kV/kV with 2 × 31.5 MVA transformers. Also, by applying the method, influence of system for condition monitoring of transformer windings and oil on failures repair cost and load curtailment cost is evaluated.

Serbian Journal of Electrical Engineering

This paper presents a method for determining optimal arrangements of parallel independent overhea... more This paper presents a method for determining optimal arrangements of parallel independent overhead power lines aimed to decrease electric and magnetic field emissions. The Genetic Algorithm (GA) is used to find the optimal placement of conductors. The Monte Carlo approach implemented in GA allows consideration of uncertain phase shifts between independent overhead power lines. The results and practical aspects of the proposed methodology are illustrated on two different configurations of both independent 400 kV singlecircuit and double-circuit overhead power lines.

Serbian Journal of Electrical Engineering, 2016

The paper presents the dynamic model of maintenance costs of the power transformer functional com... more The paper presents the dynamic model of maintenance costs of the power transformer functional components. Reliability is modeled combining the exponential and Weibull's distribution. The simulation was performed with the aim of corrective maintenance and installation of the continuous monitoring system of the most critical components. Simulation Dynamic System (SDS) method and VENSIM PLE software was used to simulate the cost. In this way, significant savings in maintenance costs will be achieved with a small initial investment.

Electric Power Systems Research, Feb 1, 2012

The paper suggests a procedure for determining an optimal combination of activities and measures ... more The paper suggests a procedure for determining an optimal combination of activities and measures to minimize the expected total costs during the planned exploitation period of power transformers.

Zbornik radova, Elektrotehnicki institut Nikola Tesla, 2011

Kratak sadržaj: U radu je prikazana uporedna analiza nekih mera kojima se poboljšava pouzdanost n... more Kratak sadržaj: U radu je prikazana uporedna analiza nekih mera kojima se poboljšava pouzdanost napajanja potrošača. Konkretno, analizirani su uticaj ugradnje pojedinih tipova rasklopne opreme i mogućnosti dvostranog napajanja potrošača iz susednog izvoda. Navedeni su izrazi za proračun pokazatelja SA i količine očekivane neisporučene električne energije

Electric Power Systems Research, 2010

The paper suggests a method to optimize the spare amount of power transformer components. The pro... more The paper suggests a method to optimize the spare amount of power transformer components. The proposed strategy is conceived to provide minimum annual cost consisting of expected failures renewal cost, capital cost for spares and load curtailment cost. The method identifies minor and major failures. Minor failures are repairable, while major failures can be repairable or unrepairable. Power transformer is a complex system, consisting of six components (functional parts). It is assumed that each component has two independent, competing failure modes: wear-out failure mode, modelled by two-parameter Weibull distribution, and a chance failure mode, characterized by an exponential distribution. The application of the method suggested and the benefits it provides are demonstrated for one transformer station (TS) 110/x kV/kV with 2 × 31.5 MVA transformers. In addition, the influence of performing power transformer refurbishment on expected total cost has also been analyzed.

Electric Power Systems Research, 2003

This paper suggests a probabilistic method for the calculation of operation cost throughout a pla... more This paper suggests a probabilistic method for the calculation of operation cost throughout a planning period and availability evaluation of substation components, in connection with planned maintenance activities. This method is conceived to provide lower operation cost, consisting of failure repair cost and maintenance cost, and higher availability of substation components. The method identifies minor and major failures. It is assumed that each component has two independent, competing failure modes: wear-out failure mode, modelled by a two-parameter Weibull distribution, and a chance failure mode, characterized by an exponential distribution. The application of the method suggested is demonstrated for a 145 kV air-blast circuit-breaker. By applying the method, influence of condition monitoring systems application on operation cost is evaluated. Also, because of comparison, expected operation cost in case of time-based maintenance performing is calculated. #

Electric Power Systems Research, 2008

ABSTRACT The paper suggests a method for effects evaluation of a few activities and measures, und... more ABSTRACT The paper suggests a method for effects evaluation of a few activities and measures, undertaken as a part of preventive maintenance of power transformers. The method enables calculation of expected failures repair cost and load curtailment cost. The method identifies minor and major failures. Power transformer is a complex system, consisting of five components (functional parts). It is assumed that each component has two independent, competing failure modes: wear-out failure mode, modeled by two-parameter Weibull distribution, and a chance failure mode, characterized by an exponential distribution. The application of the method is demonstrated for one transformer station (TS) 110/x kV/kV with 2 × 31.5 MVA transformers. Also, by applying the method, influence of system for condition monitoring of transformer windings and oil on failures repair cost and load curtailment cost is evaluated.

Electric Power Systems Research, 2012

Electric Power Systems Research, 2013

ABSTRACT The paper suggests a method to optimize the quantity of spare power transformer componen... more ABSTRACT The paper suggests a method to optimize the quantity of spare power transformer components. The presented sparing policy is conceived to provide minimum annual cost consisting of expected capital cost for spares, failures renewal and load curtailment costs. The method identifies minor and major failures. Power transformer is a complex system, consisting of six components (functional parts). It is assumed that each component has two independent, competing failure modes: wear-out failure mode, modeled by two-parameter Weibull distribution, and a chance failure mode, characterized by an exponential distribution. Duration of failure renewal is not a deterministic variable. It is assumed that failure state residence time of each power transformer component is Weibull distributed (renewal times of power transformer components may follow any probability distribution, Weibull distribution being only a special case).The application of the method suggested and the benefits it provides are demonstrated for one transformer station (TS) 110/x kV/kV with 2 × 31.5 MV A transformers in case of radial supplying of customers and when outage of one power transformer does not affect customers supplying. In addition, the influence of power transformer refurbishment on expected total cost has also been analyzed.

International Journal of Electrical Power & Energy Systems, 1999

ABSTRACT A method is suggested to optimize the number of spare items of substation components whi... more ABSTRACT A method is suggested to optimize the number of spare items of substation components which have to be stored at the beginning of each year throughout a planning period. This sparing policy is conceived to provide the minimum total cost consisting of investment and load curtailment costs. The method uses the Hooke and Jeeves' direct search optimization approach. The optimization method is extended to apply to typical HV/MV GIS transformer stations requiring specific reliability modeling.