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This paper describes two concepts of automatic systems for accuracy testing of current transformers. Advantages and disadvantages of both concepts are discussed. The concept of multi channel testing is used for developing of the measuring device for current transformer accuracy testing for factory FMT Zajecar. The short description of the device is presented as well as the results of its testing.
We evaluate the flying capacitor multilevel converter (FCMC) with one switched-capacitor cell under asymmetric working condition, as a highly efficient hardware realization for the virtual infinite capacitor (VIC). The VIC is a type of electronic circuit, recently introduced to replace large, expensive and unreliable electrolytic capacitors, mainly intended for smoothing random fluctuations of a DC...
The paper presents new trends in the development photovoltaic (PV) power plants, with particular reference on new inverter concept with DC-link voltage over 1000 V. For the inverters with the DC-link voltage reaching the value of 1500 V, basic and most important features will be presented. The principle of appropriate PV panel configuration selection in accordance with the inverter voltage input level...
In this paper, the excitation control with rotary exciter of generator A2 in Thermal Power Plant “Kostolac A” is presented. Excitation system under consideration consists of a main exciter, an auxiliary exciter and power semiconductor rectifiers. The main exciter is a synchronous-reluctance generator with windingless toothed rotor. That excitation system is specific due to the fact that the main exciter...
Phase-locked loops (PLLs) are doubtless the most popular synchronization technique in the power converters. Almost all proposed PLL structures known in literature are inherently nonlinear and can be linearized as second order linear time invariant system. Nonlinear nature of PLLs degrades their performances, and question arises if there exist an enhanced PLL structure that would have superior performances...
This paper proposes a fast and efficient strategy to determine the number and locations of fault indicators (FI) in medium voltage distribution networks. The objective function takes into account the most important characteristics of the network such as topology, non-uniform failure rates of the lines as well as the power demand and number of customers. For seeking the minimum of the objective function,...
Determining the reliability of the power supplies for induction heating through an analysis of the states is linked to several aspects of their operation. One of them is the transition between states — from an operating state into a protection state or from a protection state into a failure sate. To do that analysis, an Analysis of the Probabilistic States, the so called Markov Analysis, is used....
This paper covers characterization and gate drive design for high voltage, gallium nitride (GaN), high electron-mobility transistors (HEMT) in a cascode structure. Parameters of high voltage cascode GaN HEMT devices are described and compared to state-of-the-art Si MOSFET devices. Challenges in designing high frequency GaN based power converter and common design practices are described. Effects of...
An approach is developed in the paper to model parameter extraction of photovoltaic (PV) modules based on manufacturer's datasheet characteristics. The model parameters are obtained simultaneously for any environmental conditions (irradiance and temperature). The computer realization of the parameter extraction procedure is performed using the general-purpose circuit simulator PSpice and postprocessing...
The use of LCL filters is a well accepted solution to attenuate the harmonics created by the pulsewidth modulation (PWM). However, inherently LCL filters have a resonance region where the unwanted harmonics are amplified, which can compromise instability. Active damping strategies are implemented as a countermeasure. This paper analyses the robustness of the closed-loop dynamics when different active...
This paper proposes a high-performance speed measurement method for electric drives using incremental encoders. The proposed solution improves the period-based speed estimation method. Such methods suffer from low resolution of time measurement at high speeds. The proposed method solves this problem by processing every speed estimation between the consecutive execution of the speed controller predicting...
This paper describes technical details regarding the construction and economic viability of renewable energy sources, with particular reference to the techno-economic analysis of solar PV plants in the Republic of Serbia. The potentials of solar energy are described, as well as a chronological overview of various Regulations for privileged producers of electricity from renewable energy sources and...
A systematic analytical procedure based on the concept of the analytic signal (AS) of Gabor is used to estimate amplitude and phase of input multi-harmonic signal. To this end, assuming the signal fundamental frequency is known in advance (i.e., estimated at an independent stage), the reduction in complexity is achieved owing to completely new analytical and summarized expressions that enable a quick...
This paper describes originally designed monophase power quality data logger (PQL), a successor of monophase power quality analyzer (PQA) presented earlier. The primary purpose of the analyzer was to illustrate the capabilities of the used development board to the students of Microprocessor software and to help the students of Power networks to visualize disturbances generated by different electronic...
Power electronics converters are essential and critical components of the new power-systems paradigm where renewable energy sources are expected to play a significant role in the future worldwide energy portfolio. In this paper, the flexibility of PV converters is exploited, proposing a novel method for tracking an external power-reference in real-time which generally differs from the maximum power...
Voltage dips are significant threat for distributed generation (DG) connected via grid-tie inverter to the power system. Fast detection of voltage dips is essential for proper operation of the DGs. The paper presents an overview of different methods for their detection. The dips can be traced by appearance of voltage harmonics. Therefore, categorization of harmonics estimation techniques is given...
Shunt Active Power Filter (APF) is a custom power device applied in electric grid system in order to compensate harmonic currents generated by nonlinear loads. Shunt APF operates by firing power electronic devices of voltage source inverter (VSI) to produce the compensation currents. The VSI also generates high frequency switching ripple harmonics that distorts the source current. High order filters,...
This paper deals with the mechanical solutions for installation of innovative direct-drives suited for steering gears onboard ships. The work is comprised in a research project commissioned by the Italian Navy. The research aims to realize a full-electric and oil-free drive for actuation of hydraulic loads in the perspective of more “green ships”. The electrical drives proposed are based on a fractional...
We propose a plug-and-play realization of the virtual infinite capacitor (VIC), which is an electronic circuit recently proposed in the literature for DC voltage filtering. The VIC is meant to replace large, expensive and unreliable electrolytic capacitors, and is mainly intended for applications where random fluctuations of the DC bus voltage may occur (i.e., the VIC is not tuned to one particular...
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