Marko Vukobratović

Optimal Distributed Generation placement in distribution network

This paper presents a method for optimal Distributed Generation placement with goal of reducing active power system losses and voltage level regulation. Active power losses in radial distribution network are determined using an Artificial Neural Network (ANN) by simultaneous formulation for the determination process based on voltage level control and injected power. Adequate installed power of distributed generation and the appropriate terminal for distributed generation utilization are selected by means of a genetic algorithm (GA), performed in a distinct manner that fits the type of decision-making assignment. The training data for ANN is obtained by means of load flow simulation performed in DIgSILENT PowerFactory software on a part of the Croatian distribution network. The active power losses and voltage conditions are simulated for various operation scenarios in which the back propagation ANN model has been tested to predict the power losses and voltage levels for each system terminal, and GA is used to determine the optimal terminal for distributed generation placement.

Infrared thermography as control of handheld IPL device for home-use

ABSTRACT Infrared thermography as contactless method for determining the temperature distribution on the surface is used for analyzing the impact of intense pulsed light hair removal device (IPL) on the skin. Depth of light penetration depending of wavelength is described as well as absorption curves and IPL impulse shapes. Energy balance and IPL impulse influence on the skin is analyzed. Melanin temperature rise by different fluence operation and temperature distribution in the modeled hair is used in order to determine overall skin temperature rise. Estimated energy balance provided by mathematical model has been confirmed with experimental results. Performed measurements, beside determination of the right emissivity, required the identification of most significant parameter in the process which proved to be the skin reference temperature and real temperature rise. Practical IPL application with detailed body temperature analysis is comprehensively described and thermal imaging interpretation problem and determination of the temperature rise is observed.

The evolutionary optimization approach for voltage profile estimation in a radial distribution network with a decreased number of measurements

The procedure for estimation of voltage profile in a radial distribution network considering decreased number of measurements is presented in the text. The proposed procedure is based on hypothesis that feeder voltage profile in case of the limited number of feeder measurements can be successfully estimated using evolutionary optimization approach. The procedure consists of two main steps. In the first step, the location of the voltage measurements are determined with aim to have as small as possible the number of the locations. This is done by applying the analytical mathematical procedure. After the measurement locations are defined, in the second procedure step the optimization aims to estimate whole voltage profile is performed employing the evolutionary algorithm. The proposed procedure is tested on two test radial distribution feeders to verify the proposed procedure.

VOLTAGE AND POWER LOSSES CONTROL USING DISTRIBUTED GENERATION AND COMPUTATIONAL INTELLIGENCE

The paper analyzes the possibility of reducing active power losses in power system, constrained by regulated voltage levels, by implementing appropriate distributed generation capacity. The objectives of this paper were achieved by developing hybrid methods based on artificial neural network and genetic algorithm. Methods have been developed to determine the impact of different distributed generation power on all terminals in the observed system. The method that uses artificial neural network and genetic algorithm is applicable for radial distribution networks, and method using load flow and genetic algorithm is applicable to doubly-fed distribution network. For comparison purposes, additional method was developed that uses neural networks for the decision-making process. Data for training the neural network was obtained by power flow calculation in the DIgSILENT PowerFactory software on a part of Croatian distribution network. The same software was used as an analytical tool for checking the correctness of solutions obtained by optimization.

Protection Coordination and Anti Islanding Protection Solution for Biomass Power Plant Connected on Distribution Network

Protection coordination as well as anti-island protection play significant role in the process of biomass power plant connection on the distribution network. Distribution generation island operation in Croatia is unacceptable according to the existing National grid code Paper presents a protection coordination of all passive protections used in the real biomass power plant and connected distriubution network feeder. Short-circuits three phase, two phase and single line to ground faults and generator islanding simulations have been performed and simulated in the time domain at the different network locations using DIgSILENT Power Factory software. The time-current plots coordination of protective devices are made using Smart PDC module in Easy Power Protector software tool. Full Text: PDF DOI: http://dx.doi.org/10.11591/ijece.v6i6.11418

Evolutionary optimization approach for performing interval power flow considering uncertainties in electric power systems

The paper deals with problem of power flow calculation if there are uncertainties present in power distribution network variables or parameters. Load, network parameters and supply uncertainties can be represented by ranges of values. From mathematical point of view these ranges can be defined as intervals, fuzzy numbers or a probability density function. Since the input data are interval instead crisp numbers, the question is what bounds of the power flow output variables are. Literature suggests various methods such as probabilistic power flow, bound power flow and interval and fuzzy arithmetic for calculating power flow considering uncertainties. The proposed approach is based on optimization problem formulation. The presence of uncertainties is defined in optimization problem form with minimization and maximization of power flow output quantities as objective functions of the optimization. The uncertainties in input quantity are taken into account through optimization problem inequality constraints. The evolutionary algorithm is used to solve the optimization problem. The standard power flow calculation for crisp numbers is used instead power flow based on interval or fuzzy arithmetic. The proposed procedure is realized through co-simulation between PSAT and MATLAB computer programs. The proposed approach is tested on IEEE 14 node test distribution feeder. The simulation results indicate that proposed procedure has capability to solve considered problem.