Mirko Todorovski

Ss. Cyril and Methodius University in Skopje · Faculty of Electrical Engineering and Information Techologies

This paper presents a two-level robust optimal feeder routing model for the planning of radial distribution networks where power demand is uncertain. The robust model is solved by implementing the column and constraint generation strategy. The optimization goal is to find routes that provide minimal total annual costs that satisfy parameters for qu...

Throughout the past few decades, the share of distributed generation in power systems has increased continuously. This increasing trend coupled with the continuous demand growth in the distribution systems started a shift towards heavier reactive power consumption. The latter paved the way for the development of advanced operational and planning al...

This paper offers affordable controlled charging and a vehicle-to-grid solution that uses a non-smart power meter. Additional communication infrastructure in the low-voltage distribution network is not needed. Ladder logic control is developed to be easily implemented by any commercial programmable logic controller. The voltage values measured by t...

Different configurations of counterpoises are often used to reduce the resistance and impulse impedance of the transmission line grounding. However, there are no general rules for an actual design. This paper analyses the performance of several configurations of counterpoises under typical lightning current impulses. The basis is a parametric analy...

Single horizontal and vertical grounding electrodes are often used for an earth connection of the lightning protection system. However, there are many practical situations when such electrodes have to be enhanced for better efficiency and replaced by multiple horizontal, vertical and/or inclined electrodes. This paper presents a systematic approach...

Voltage drop developed between the grounding electrode under lightning current and distant neutral ground determines the protection efficiency. The peak value of such voltage can be computed from known impulse impedance and current peak value. For the first time, in this paper, general formulas are de-rived for impulse impedance of horizontal and v...

Among other things, in a detailed analysis of circumstances in power systems of great importance is the knowledge on contribution of individual generators to loads, and to currents and power losses in network elements. This work proposes an efficient method for obtaining these details. The method uses results of a power flow calculation, utilizes s...

The focus of the research presented here is developing a method to calculate contribution of each generator-load pair in total distribution network power losses. To do this we calculate current component from any generator to any load and then multiply each of these conjugate current components by difference between corresponding generator node vol...

Many studies and scientific papers have been published that consider the integration of renewable sources in energy systems, using the least-cost optimization models as a long-term generation expansion planning tool. Supplementary to these analyses, this paper focuses on the transmission network capacity for acceptance of variable renewable energy....

The energy hub concept has proven itself highly useful for the integrated modelling of smart energy systems and has been widely applied for analyzing systems of multiple, mutually interconnected consumers of different energy carriers. A thorough literature review sheds light on the tendency of recent works to simplify the network flows, mainly thro...

A function to simulate lightning return stroke current as a sum of two exponential terms is presented. The exponent of the first term is a linear function of time, while the exponent of the second term is a power function of time with degree n. Compared with the function from IEC 62305-1, the proposed function offers slightly different front of the...

We propose a dynamic intelligent load balancing and reactive power compensation switch plugin for power meters and a smart scalable system architecture applicable as addon on top of the existing power distribution networks. The load balancing module will improve the load balance in a network and thus decrease the power losses, whereas the distribut...

Efficient control of power systems is becoming increasingly difficult as they gain in complexity and size. By considering a power grid and a communication infrastructure as a multiplex network, we propose an automatic control strategy that regulates the mechanical power output of the generators based on information obtained via communication links...

A REKK és a DNV GL konzorciuma a 2013-as első PECI lista kiválasztásában nyújtott tanácsadó munkája után 2016-ban is támogatást nyújtott a második PECI lista kiválasztáshoz. A konzorcium kialakított egy projekt értékelési módszertant, majd az elfogadott módszertan alapján értékelte a benyújtott infrastruktúra projekteket. Az értékelés egy előzetes...

Using the existing hierarchical, client-server addressing concepts and identifying the load balancing problem among phases in 3-phase systems, we propose a novel, very simple algorithm for dynamic intelligent load balancing (DILB), that decreases the power losses in a power distribution network (PDN). Our solution is easily applicable to every part...

The building blocks of the equivalent circuit of a complex grounding system are individual equivalent circuits of all system elements, which are represented with their equivalent $\pi$-circuit. In this paper we focus on underground single core cable lines with ground return wire, which are very common elements in distribution networks. We model the...

Genetic Algorithm with special constraint handling procedure is proposed for the discrete optimisation problem of capacitor placement and sizing in distribution system for cost reduction and power quality improvement. We use gene encoding that enables simple integer representation of possible different number of capacitors of various standard sizes...

A new model to simulate return stroke lightning current is presented. The idea for the model arose from the observation that measured lightning current has two quite different parts. The first part is fast rise from initiation to peak value and the second part is the slow decay following peak value. Consequently, we propose two functions to represe...

Plug-in electrical vehicles (PEV) are capable of both grid-to-vehicle (G2V) and vehicle-to-grid (V2G) power transfer. The advantages of developing V2G include an additional revenue stream for cleaner vehicles, increased stability and reliability of the electric grid, lower electric system costs, and eventually, inexpensive storage and backup for re...

The non-linear integer problem of capacitor placement in distorted distribution systems is solved with discrete values of capacitor sizes employing integer genetic algorithm with controlled random initialization. The objective function contains yearly system operation costs including cost of energy losses and capacitor prices. Different load models...

This paper presents an approach of modelling single-core cable line and a parallel laid additional conductor. Results are presented from various analyzed cases, which include situations when the additional conductor is not laid along full cable length. The proposed pproach besides offering a possibility to reduce complex multiphase cable line to a...

A Clustering Based Optimization (CBO) for the discrete optimisation problem of fixed shunt capacitor placement and sizing is presented. We minimize the sum of costs for power/energy losses and capacitor costs. Over-compensation and voltage constraints are also taken into consideration. CBO is based on a simple search which iteratively loops through...

Plug-in electric vehicles (PEVs) can serve in discharge mode as distributed energy and power resources operating as vehicle-to-grid (V2G) devices and in charge mode as loads or grid-to-vehicle (G2V) devices. It has been documented that PEVs serving as V2G systems can offer possible backup for renewable power sources, can provide reactive power supp...

Efficient control of power systems is becoming increasingly difficult as they gain in complexity and size. We propose an automatic control strategy that regulates the mechanical power output of the generators in a power grid based on information obtained via a communication infrastructure. An algorithm that optimizes steady-state stability of a pow...

Transient stability and steady-state (small signal) stability in power girds are reviewed. Transient stability concepts are illustrated with simple examples; in particular, we consider three methods for computing region of attractions: time-simulations, extended Lyapunov function, and sum of squares optimization method. We discuss steady state stab...

This letter presents a compact transformer voltage regulation expression which accounts for off-nominal tap position and voltage deviation from the nominal value. The expression is validated through comparison with the common expressions used in the literature. It is shown that primary/secondary voltage variation has certain influence on the result...

This paper presents two approaches where the single-core cable line and an additional conductor laid in parallel can be reduced to a simple equivalent pi-circuit containing an active element beside the usual passive impedances. The parameters of the equivalent circuit are calculated using a numerical approach where the distributed parameter line wa...

The paper presents an approach where traditional PTDF (Power Transfer Distribution Factors) matrix is reduced in size so that it reflects sensitivities of branch flows to changes in nodal power injections at generator buses only. The advantage of the reduced PTDF matrix is in both reductions of decision variables in the optimization procedure and n...

The nonlinear integer problem of capacitors placement in distribution system is solved with discrete values of capacitor sizes and selection of their locations. We use integer genetic algorithm with controlled random initialization. The objective function is yearly system operation costs including costs for energy losses and for capacitor installat...

A case study approach is applied in order to evaluate climate change mitigation measures in the energy sector in a SEE country with economy in transition. Starting point of the analyses were the findings and recommendations of the Working Group on Mitigation (WG3) of the Intergovernmental Panel on Climate Change (IPCC), Bangkok, May 2007. The appli...

The recently published idea of treating voltage angles at generator-buses as control variables enables to obtain voltages at load-buses with less computation. However, application of this approach in solving the optimal power flow problem by genetic algorithms may be ineffective if starting values of voltage angles are selected quite randomly. To o...

This paper presents a new power flow method tailored for genetic algorithms application in solving optimal power flow problems. Generating units, the only controllable elements for which four variables are associated, were given special attention, since they influence to great extent both speed and robustness of any power flow method. In this paper...

The admittance summation method is efficient in short circuit analysis of radial and weakly meshed networks. It is especially powerful if all node loads can be represented as any combination of constant impedance and constant current load component. However, in the existing literature one cannot find any explanation how to handle power transformer...

The First National Communication is a very first national report on the country's conditions regarding climate change issue, prepared following the guidelines adopted by CoP preparation of national communications by Parties not included in the Annex I to the Convention. Preparation of the National Communication is seen as an initial step in the act...

The First National Communication is a very first national report on the country's conditions regarding climate change issue, prepared following the guidelines adopted by CoP preparation of national communications by Parties not included in the Annex I to the Convention. Preparation of the National Communication is seen as an initial step in the act...