Zdraveski V, Angelov J, Vuletic J and Todorovski M (2024), "Load supplying capability under
uncertain power demand conditions", Electric Power Systems Research. Vol. 237, pp. 111029.
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: This paper presents a comprehensive study on the Load Supplying Capability (LSC) of
high voltage (HV) transmission networks, with a focus on robust model formulation under uncertain
power demand conditions. Our primary objective is to calculate the LSC, considering factors like
network topology, line and generation capacities, and especially load demand uncertainties. We
initially establish a deterministic LSC model as a baseline. This model incorporates various
constraints and an objective function to maximize the load supply. In advancing to a robust LSC
model, we address the inherent uncertainty in load demand forecasting, modelling it as a range of
values within a polyhedral uncertainty set. This model operates in two stages: first, incorporating
the worst-case scenario for uncertain power demand, and then maximizing the LSC within operational
constraints. |
BibTeX:
@article{Zdraveski2024a,
author = {Vasko Zdraveski and Jordanco Angelov and Jovica Vuletic and Mirko Todorovski},
title = {Load supplying capability under uncertain power demand conditions},
journal = {Electric Power Systems Research},
year = {2024},
volume = {237},
pages = {111029},
url = {https://www.sciencedirect.com/science/article/pii/S0378779624009155},
doi = {10.1016/j.epsr.2024.111029}
}
|
Zdraveski V and Todorovski M (2024), "A robust optimization model for Optimal Feeder Routing and
Battery Storage Systems design", Applied Energy. Vol. 374, pp. 123978.
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: The increasing integration of small-scale distributed generation units and electric
vehicle present significant challenges to the design of urban electrical distribution networks (DN),
introducing considerable uncertainties. This paper addresses these complex challenges by proposing
an Optimal Feeder Routing and Battery Storage System (OFRBSS) model. The model offers a
single-stage, long-term optimization framework that simplifies load uncertainty to two values –
minimum and maximum power demand – thereby enhancing simplicity and efficiency in modelling power
demand uncertainty. Leveraging the Column and Constraint Generation algorithm, the OFRBSS model
optimizes feeder routing and battery storage system installation, enabling distribution system
operators to meet operational constraints under worst power demand conditions. This research bridges
existing gaps in integrating optimal DN planning, battery storage system sizing, and placement while
addressing the critical aspect of power demand uncertainty. The three-level OFRBSS model is
transformed into a two-level counterpart through the application of Karush–Kuhn–Tucker conditions.
|
BibTeX:
@article{Zdraveski2024,
author = {Vasko Zdraveski and Mirko Todorovski},
title = {A robust optimization model for Optimal Feeder Routing and Battery Storage Systems design},
journal = {Applied Energy},
year = {2024},
volume = {374},
pages = {123978},
url = {https://www.sciencedirect.com/science/article/pii/S0306261924013618},
doi = {10.1016/j.apenergy.2024.123978}
}
|
Grcev L, Markovski B and Todorovski M (2024), "On Communication Tower Grounding Under Lightning
Currents", IEEE Transactions on Electromagnetic Compatibility. , pp. 1-4.
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: The recommended typical grounding of a communication tower comprises a ring
with radial counterpoises. However, guidance on determining the size and layout for actual
practical situations is lacking. This letter presents simple formulas for grounding
resistance, impulse impedance, and effective length of the radial counterpoises, which can help
analyze optimal grounding configurations for lightning protection.
|
BibTeX:
@article{Grcev2024,
author = {Grcev, Leonid and Markovski, Blagoja and Todorovski, Mirko},
title = {On Communication Tower Grounding Under Lightning Currents},
journal = {IEEE Transactions on Electromagnetic Compatibility},
year = {2024},
pages = {1-4},
url = {https://ieeexplore.ieee.org/document/10561587},
doi = {10.1109/TEMC.2024.3410093}
}
|
Todorovski M and Rajičić D (2024), "Decomposing total power flows into contributions originating
from
power sources in loads, generators, and network elements", Electric Power Systems Research.
Vol.
233, pp. 110433.
[Abstract]
[BibTeX] [DOI] [URL]
|
Abstract: To thoroughly analyze the conditions in power lines, transformers or loads, it is
essential to have knowledge of their active and reactive power flow contributions from each power
source. Understanding these contributions allows for a detailed analysis of the impact of active and
reactive power flow contribution from each power source on active and reactive power losses in each
network element, as well as the determination of power participation of each source to every load.
This
paper provides the necessary equations and an adequate procedure for calculating power flow
contributions. The method is suitable for meshed network and considers shunt elements, avoiding
problematic simplifications. Furthermore, it ensures impartiality towards any network user, making
it
well-suited for application in deregulated environments. By offering valuable information useful,
this
method supports the creation of transparent and non-discriminatory agreements between network
operator
and users. |
BibTeX:
@article{Todorovski2024a,
author = {Mirko Todorovski and Dragoslav Rajičić},
title = {Decomposing total power flows into contributions originating from power sources in loads, generators, and network elements},
journal = {Electric Power Systems Research},
year = {2024},
volume = {233},
pages = {110433},
url = {https://www.sciencedirect.com/science/article/pii/S0378779624003213},
doi = {10.1016/j.epsr.2024.110433}
}
|
Todorovski M (2024), "A Reduction Method for Radial Distribution Feeders: Ensuring Parity in
Voltages and Losses", IEEE Transactions on Power Systems., March, 2024, Vol. 39. No. 2 pp.
4759-4762.
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: High-resolution power flow simulations for the detailed distribution system are
resource-intensive and time-consuming. In the past, various methods have been proposed to create a
simplified equivalent circuit while preserving essential characteristics. However, discrepancies in
power losses between original and equivalenced feeders were observed. To resolve this issue, a
modification is suggested to maintain equality in the voltage drop, total feeder current/power, and
losses. Explicit formulas for multiple bus reduction are provided. Examples demonstrate the
effectiveness of the proposed method. |
BibTeX:
@article{Todorovski2024,
author = {Todorovski, Mirko},
title = {A Reduction Method for Radial Distribution Feeders: Ensuring Parity in Voltages and Losses},
journal = {IEEE Transactions on Power Systems},
year = {2024},
volume = {39},
number = {2},
pages = {4759-4762},
url = {https://ieeexplore.ieee.org/document/10384771},
doi = {10.1109/TPWRS.2024.3351490}
}
|
Todorovski M, Grcev L and Markovski B (2023), "An Image Method for Evaluating Partial Inductance
in
Conducting Half-Space", IEEE Transactions on
Electromagnetic Compatibility. Vol. 65, No. 6, pp. 1998-2005.
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: Partial inductances are required in the circuit-based models of wire-like
structures within a
conducting half-space. Different approaches were used to calculate partial inductances, which mainly
varied
between applying or not applying the mirror image theory. The mirror image theory is applied to the
electric
field; however, the rigorous analysis in this article shows that it does not hold for the magnetic
field in the
general case. This article introduces an accurate image method developed for the magnetic field in a
conducting
half-space suitable for practical computations. New closed-form formulas for partial inductances
were derived
for some typical cases, but for the general case with conductors in arbitrary positions, it is more
efficient to
use numerical integration. For such a purpose, a MATLAB script is provided. It has been shown that
frequently
used approximations can lead to significant errors. |
BibTeX:
@article{Todorovski2023,
author = {Todorovski, Mirko and Grcev, Leonid and Markovski, Blagoja},
title = {An Image Method for Evaluating Partial Inductance in Conducting Half-Space},
journal = {IEEE Transactions on Electromagnetic Compatibility},
year = {2023},
volume = {65},
number = {6},
pages= {1998-2005},
url = {https://ieeexplore.ieee.org/document/10316234},
doi = {10.1109/TEMC.2023.3329037}
}
|
Zdraveski V, Vuletic J, Angelov J and Todorovski M (2023), "Radial distribution network planning
under
uncertainty by implementing robust optimization", International Journal of Electrical Power
& Energy
Systems. Vol. 149, pp. 109043.
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: 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 quality of supply and technical constraints under the worst uncertain
power demand
realization. The model incorporates annual capital recovery, energy loss, and undelivered energy
costs. The
column and constraint generation strategy was developed using a mixed-integer quadratically
constraint
programming model capable of obtaining a deterministic solution to the optimal feeder routing
problem. |
BibTeX:
@article{Zdraveski2023,
author = {Vasko Zdraveski and Jovica Vuletic and Jordanco Angelov and Mirko Todorovski},
title = {Radial distribution network planning under uncertainty by implementing robust optimization},
journal = {International Journal of Electrical Power & Energy Systems},
year = {2023},
volume = {149},
pages = {109043},
url = {https://www.sciencedirect.com/science/article/pii/S014206152300100X},
doi = {10.1016/j.ijepes.2023.109043}
}
|
Grcev L, Markovski B and Todorovski M (2023), "Lightning Efficient Counterpoise Configurations
for Transmission Line Grounding", IEEE Transactions on Power Delivery. , pp. 877-888.
[Abstract] [BibTeX] [DOI]
|
Abstract: 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 analysis derived from time responses
of 11,386 test cases for each configuration with parameters in broad ranges computed using a
rigorous electromagnetic model based on the method of moments. The contributions of the paper are:
Simple formulas for the resistance, impulse impedance, and effective length of counterpoise
configurations are derived from and verified by the simulation results; a configuration with an
8-leg counterpoise bent parallel to the line is proposed, which extends the effective length and is
efficient in high resistivity soil; and the method does not depend on the different lightning
current impulse waveform representations based on Heidler, CIGRE, and double-exponential formulas,
since the results can be easily converted. A simple procedure is provided to compare the
capabilities and limitations of counterpoise configurations. New formulas and procedures make up a
general and straightforward method for analyzing the optimal design, considering the cost-effective
and best protection against lightning. |
BibTeX:
@article{Grcev2023,
author = {Grcev, Leonid and Markovski, Blagoja and Todorovski, Mirko},
title = {Lightning Efficient Counterpoise Configurations for Transmission Line Grounding},
journal = {IEEE Transactions on Power Delivery},
year = {2023},
month = {April},
pages = {877-888},
doi = {10.1109/TPWRD.2022.3200579}
}
|
Malčeski S, Vuletić J, Todorovski M and Angelov J (2022), "Optimal sizing and
placement of
D-SVC in radial distribution systems using an exhaustive analytical search", International
Journal of
Applied Electromagnetics and Mechanics. Vol. 69, pp. 279-292. IOS Press.
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: 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 algorithms for power distribution systems. Following these
trends in the
distribution systems, the distribution grids must be developed with greater reliability and
flexibility, i.e.
smart grids. Consequently, the implementation of smart technologies instead of traditional ones
should be
considered wherever feasible. This paper presents an approach for optimal placement, economic
sizing, and
operation point search of distribution static VAR compensator (D-SVC) using an exhaustive analytical
search. The
proposed algorithm introduces quite a few novelties, unique, superior, and repetitive results
presented on a
distribution test system IEEE 69. |
BibTeX:
@article{Malceski2022,
author = {Malčeski, Stojan and Vuletić, Jovica and Todorovski, Mirko and Angelov, Jordančo},
title = {Optimal sizing and placement of D-SVC in radial distribution systems using an exhaustive analytical search},
journal = {International Journal of Applied Electromagnetics and Mechanics},
publisher = {IOS Press},
year = {2022},
volume = {69},
pages = {279-292},
url = {https://doi.org/10.3233/JAE-210200},
doi = {10.3233/JAE-210200}
}
|
Zdraveski V, Angelov J, Krstevski P, Mateska AK, Vuletic J and Todorovski M (2022),
"Decentralized controlled
charging and vehicle-to-grid solution for voltage regulation in low voltage distribution
systems",
Journal of Electrical Engineering. Vol. 73(2), pp. 99-107.
[BibTeX] [DOI] [URL]
|
BibTeX:
@article{Zdraveski2022,
author = {Vasko Zdraveski and Jordanco Angelov and Petar Krstevski and Aleksandra Krkoleva Mateska and Jovica Vuletic and Mirko Todorovski},
title = {Decentralized controlled charging and vehicle-to-grid solution for voltage regulation in low voltage distribution systems},
journal = {Journal of Electrical Engineering},
year = {2022},
volume = {73},
number = {2},
pages = {99--107},
url = {https://doi.org/10.2478/jee-2022-0013},
doi = {10.2478/jee-2022-0013}
}
|
Grcev L, Markovski B and Todorovski M (2022), "Lightning Performance of Multiple Horizontal,
Vertical and
Inclined Grounding Electrodes", IEEE Transactions on Power Delivery., Oct, 2022. Vol. 37(5),
pp.
3782-3791.
[Abstract] [BibTeX] [DOI]
|
Abstract: 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 to evaluating and comparing the lightning performance of such
grounding
arrangements based on simple formulas. The contributions of this paper are: It is shown that impulse
impedance Z
may be derived from known formulas for low-frequency grounding resistance R; a new definition of
effective
length is introduced that allows for such a derivation; a collection of accurate formulas for R of
all
considered grounding electrode arrangements is presented; and a new concept of “effective volume” is
described
that enables a simple procedure to increase electrodes’ effective length. The new formulas for R, Z,
and
effective length of the different electrode arrangements allow an analysis that might help search
for a choice
of cost-effective configuration and dimensions of the grounding systems in the early design stage.
|
BibTeX:
@article{Grcev2022,
author = {Grcev, Leonid and Markovski, Blagoja and Todorovski, Mirko},
title = {Lightning Performance of Multiple Horizontal, Vertical and Inclined Grounding Electrodes},
journal = {IEEE Transactions on Power Delivery},
year = {2022},
volume = {37},
number = {5},
pages = {3782-3791},
doi = {10.1109/TPWRD.2021.3137361}
}
|
Todorovski M, Angelov Jordančo and Vuletić J (2021), "Solving Tridiagonal Symmetric Systems of
Equations Using Circuit Theory Approach", IAENG International Journal of Computer Science.,
Sep, 2021. Vol. 48(3), pp. 663-671.
[Abstract] [BibTeX] [URL]
|
Abstract: This paper introduces a novel solution method for solving symmetric tridiagonal
systems. The main idea behind it is to construct a specific electric circuit with the same
node-voltage equations as the original system. This circuit has a specific "ladder" structure that
is efficiently solved using a methodology known as admittance summation method. The proposed method
avoids possible zero divisions by exploiting a specific circuit structure. This specific property is
an equivalent to a pivoting strategy used in other methods. Performance tests show that the proposed
method is comparable to Thomas algorithm, Gaussian elimination adapted for tridiagonal systems and
Matlab backslash operator. The procedure executes O(N) times meaning that computation time is
linearly proportional to system size. The whole method is coded very concisely. |
BibTeX:
@article{Todorovski2021,
author = {Todorovski, Mirko and Angelov, Jordančo, and Vuletić, Jovica},
title = {Solving Tridiagonal Symmetric Systems of Equations Using Circuit Theory Approach},
journal = {IAENG International Journal of Computer Science},
year = {2021},
volume = {48},
number = {3},
pages = {663-671},
url = {http://www.iaeng.org/IJCS/issues_v48/issue_3/IJCS_48_3_24.pdf}
}
|
Grcev L, Markovski B and Todorovski M (2021), "General
Formulas for Lightning Impulse Impedance of Horizontal and
Vertical Grounding Electrodes", IEEE Transactions on Power
Delivery., Aug, 2021. Vol. 36(4), pp. 2245-2248.
[Abstract] [BibTeX] [DOI]
|
Abstract: 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 letter, general
formulas are derived for impulse impedance of horizontal and
vertical electrodes valid for any length up to 100 m, soil's
resistivity of 30 to 1000 Ωm, and current impulse front time of
0.2 to 10 μs. Waveforms of typical lightning impulses given in
IEC standards are used, but it is shown that results are also
relevant for other impulse waveforms. Soil ionization effects
are taken into account, and the accuracy of the formulas is
investigated. New formulas enable an estimate of lightning
protection grounding's surge efficiency in a wide range of
practical situations. |
BibTeX:
@article{Grcev2021,
author = {Grcev, Leonid and Markovski, Blagoja and Todorovski, Mirko},
title = {General Formulas for Lightning Impulse Impedance of Horizontal and Vertical Grounding Electrodes},
journal = {IEEE Transactions on Power Delivery},
year = {2021},
volume = {36},
number = {4},
pages = {2245-2248},
doi = {10.1109/TPWRD.2021.3080137}
}
|
Rajicic D and Todorovski M (2021), "Participation of Every Generator to Loads, Currents and Power
Losses", IEEE Transactions on Power Systems., March, 2021, Vol. 36(2), pp. 1638-1640.
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: 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 specific power system model, and applies
the
superposition theorem. The method does not contain problematic assumptions or simplifications and it
is
easy to apply. It allows getting important facts enabling us to establish transparent and
non-discriminatory relationships between net-work operators, electricity producers and consumers.
|
BibTeX:
@article{Rajicic2020,
author = {D. Rajicic and M. Todorovski},
title = {Participation of Every Generator to Loads, Currents and Power Losses},
journal = {IEEE Transactions on Power Systems},
year = {2021},
volume = {36},
number = {2},
pages = {1638-1640},
url = {https://ieeexplore.ieee.org/document/9293183},
doi = {10.1109/TPWRS.2020.3044485}
}
|
Todorovski M and Rajičić D (2020), "Contribution of generator-load pairs in distribution networks
power losses", International Journal of Electrical Power & Energy Systems. Vol. 115, pp.
105433.
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: 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 voltage and load node voltage.
This way there are no quadratic expressions and problems with non-separability of losses. Also, the
procedure breaks down the losses in such a way that one may investigate how each power transaction
contributes to the losses. The idea to create such kind of method is to assist network users
(producers
and consumers) obtaining detailed information about distribution of power losses among network
branches,
and base on this information to consider corresponding transparent and non-discriminatory actions.
Developing the method, no problematic assumptions or simplifications were used. Hence, the method is
exact and do not consider privilege to any network user. In addition, it handles PV nodes without
additional inconveniencies. Accordingly comparing this method with methods allocating losses to
nodes it
is understandable to identify dissimilarities. Moreover, this version of the method is applicable to
radial distribution network with neglected influence of line shunt susceptances. The whole procedure
is
illustrated with a simple numerical example and it is also applied to a bigger system. The MATLAB
code
is given as an open-source for further research. |
BibTeX:
@article{Todorovski2020,
author = {Mirko Todorovski and Dragoslav Rajičić},
title = {Contribution of generator-load pairs in distribution networks power losses},
journal = {International Journal of Electrical Power & Energy Systems},
year = {2020},
volume = {115},
pages = {105433},
url = {http://www.sciencedirect.com/science/article/pii/S0142061519304661},
doi = {10.1016/j.ijepes.2019.105433}
}
|
Taseska-Gjorgievska V, Todorovski M, Markovska N and Dedinec A (2019), "An Integrated Approach
for
Analysis of Higher Penetration of Variable Renewable Energy: Coupling of the Long-Term Energy
Planning Tools and Power Transmission Network Models", Journal of Sustainable Development of
Energy, Water and Environment Systems.
[Abstract]
[BibTeX] [DOI] [URL]
|
Abstract: 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 hypothesis is that the simplified electric
power transmissions system in the long-term planning modelling tools does not reflect properly the
capacity for integration of the variable renewable energy. An integrated approach is applied with
aim to
incorporate the grid expansion needs and costs (using Direct Current Load Flow analysis), necessary
for
increased renewable electricity penetration. The already developed MARKAL – Macedonia model will be
used
as a case study. After several iterations and feedback loops between the MARKAL- Macedonia and the
network model, the expected outcome is to achieve a new cost-effective solution for deployment of
variable energy on a larger scale. |
BibTeX:
@article{Gjorgievska2018journal,
author = {Verica Taseska-Gjorgievska and Miko Todorovski and Natasa Markovska and Aleksandar Dedinec},
title = {An Integrated Approach for Analysis of Higher Penetration of Variable Renewable Energy: Coupling of the Long-Term Energy Planning Tools and Power Transmission Network Models},
journal = {Journal of Sustainable Development of Energy, Water and Environment Systems},
year = {2019},
url = {http://dx.doi.org/10.13044/j.sdewes.d7.0264},
doi = {10.13044/j.sdewes.d7.0264}
}
|
Rajicic D and Todorovski M (2018), "A Double-Exponential Lightning Current Function Suitable for
Use
of Different Sets of Input Data", IEEE Transactions on Power Delivery., Aug, 2018. Vol.
33(4),
pp. 2053-2055.
[Abstract]
[BibTeX] [DOI] [URL]
|
Abstract: 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 current impulse. In addition, this
letter
gives details how to obtain parameters of the proposed function that satisfy the given requirements.
|
BibTeX:
@article{RajicicTodorovski2018,
author = {D. Rajicic and M. Todorovski},
title = {A Double-Exponential Lightning Current Function Suitable for Use of Different Sets of Input Data},
journal = {IEEE Transactions on Power Delivery},
year = {2018},
volume = {33},
number = {4},
pages = {2053-2055},
url = {https://doi.org/10.1109/TPWRD.2017.2711268},
doi = {10.1109/TPWRD.2017.2711268}
}
|
Angelov J, Taleski R, Vuletic J, Todorovski M, Krstevski P and Krkoleva-Mateska A (2017),
"Application of Reduced PTDF Matrix in Iterative Modified DC Network Model for Cross–border
Capacity
Calculation with Consideration of Reactive Power Flow Constraints", In IEEE EUROCON 2017.,
July,
2017. (214)
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: One of the biggest threats for the security of power grids are congestion of
cross-border lines and congestion in the network itself as result of parallel flows. Nowadays,
occurrence of congestion is a result of limited network transfer capacities as a direct consequence
of
increased power transactions. One of the reasons for cross-border congestions are the unreal
cross-border capacities calculations. This is a result of assumptions and simplifications made in
the
methodologies for total transfer capacity calculation. In this paper, we propose an iterative
optimization algorithm based on modified DC network model that takes into consideration reactive
power
flows and all the constraints that comes forward. The proposed methodology is based on reduced Power
Transfer Distribution Factor (PTDF) Power Transfer Distribution Factor) matrix. This approach
successfully solves two DC Optimal Power Flow (OPF) problems: cost minimization and total transfer
capacity calculation. For testing purposes IEEE test network RTS 96 is used. |
BibTeX:
@inproceedings{Angelov2017,
author = {Jordancho Angelov and Rubin Taleski and Jovica Vuletic and Mirko Todorovski and Petar Krstevski and Aleksandra Krkoleva-Mateska},
title = {Application of Reduced PTDF Matrix in Iterative Modified DC Network Model for Cross–border Capacity Calculation with Consideration of Reactive Power Flow Constraints},
booktitle = {IEEE EUROCON 2017},
year = {2017},
number = {214},
url = {https://doi.org/10.1109/EUROCON.2017.8011148},
doi = {10.1109/EUROCON.2017.8011148}
}
|
Gjorgievski V and Todorovski M (2017), "Optimization of Complex Energy Systems", Journal of
Electrical Engineering and Information Technologies - JEEIT. Vol. 2(2), pp. 113-120.
[Abstract]
[BibTeX] [URL]
|
Abstract: According to the common practice different energy systems are analyzed separately,
without taking into consideration their mutual dependence. The goal of this paper is to illustrate
the
modeling and optimization of complex systems, i.e. multiple-energy carrier systems, by using the
energy
hub methodology. A multiple-energy carrier system consists of different energy infrastructures and
serves various types of energy demands, such as electricity, heat etc. The energy hub concept is
thus
implemented in the formulation of the economic dispatch problem for a complex energy system.
Moreover,
the paper contains a linear optimal power flow formulation of a complex system with multiple energy
hubs
interconnected with the power grid. The analysis will be conducted over simply structured systems
with
the aim of illustrating the idea of integrated modeling and the comparison of the system’s operating
points obtained by separate and integrated optimization. |
BibTeX:
@article{Gjorgievski2017,
author = {Vladimir Gjorgievski and Mirko Todorovski},
title = {Optimization of Complex Energy Systems},
journal = {Journal of Electrical Engineering and Information Technologies - JEEIT},
year = {2017},
volume = {2},
number = {2},
pages = {113-120},
url = {http://jeeit.feit.ukim.edu.mk/index.php/jeeit/article/view/74}
}
|
Pavlovski M, Gajduk A, Todorovski M and Kocarev L (2017), "Improving Power Grid Stability With
Communication Infrastructure", IEEE Journal on Emerging and Selected Topics in Circuits and
Systems., Sept, 2017. Vol. 7(3), pp. 349-358.
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: 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 (wireless or wired). An algorithm
that
optimizes steady-state stability of a power grid by iteratively adding communication links is
presented.
The proposed control scheme is successfully applied to the IEEE New England and the IEEE RTS 96
power
systems, leading to a significant increase in the steady-state stability of the systems and an
improvement in their overall robustness. The resulting communication network topology differs
significantly from the transmission grid topology. This shows how complex the steady-state control
for
power systems is, influenced by the generators' configuration, the transmission network topology,
and
the manner by which control is executed. |
BibTeX:
@article{PavlovskiGajdukEtAl2017,
author = {M. Pavlovski and A. Gajduk and M. Todorovski and L. Kocarev},
title = {Improving Power Grid Stability With Communication Infrastructure},
journal = {IEEE Journal on Emerging and Selected Topics in Circuits and Systems},
year = {2017},
volume = {7},
number = {3},
pages = {349-358},
url = {https://doi.org/10.1109/JETCAS.2017.2672679},
doi = {10.1109/JETCAS.2017.2672679}
}
|
Zdraveski V, Todorovski M, Trajanov D and Kocarev L (2017), "Dynamic Load Balancing and Reactive
Power Compensation Switch embedded in Power Meters", IEEE Transactions on Circuits and
Systems
II: Express Briefs., April, 2017. Vol. 64(4), pp. 422-426.
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: This paper proposes 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 distributed reactive power
compensator will decrease the total reactive power. The novel approach is presented from its
IT/networks
perspective as well as from the physical layer with oscilloscope measurements and time analysis of
the
phase swapping event. |
BibTeX:
@article{ZdraveskiTodorovskiEtAl2017,
author = {V. Zdraveski and M. Todorovski and D. Trajanov and L. Kocarev},
title = {Dynamic Load Balancing and Reactive Power Compensation Switch embedded in Power Meters},
journal = {IEEE Transactions on Circuits and Systems II: Express Briefs},
year = {2017},
volume = {64},
number = {4},
pages = {422-426},
url = {http://dx.doi.org/10.1109/TCSII.2016.2570338},
doi = {10.1109/TCSII.2016.2570338}
}
|
Vuletić J and Todorovski M (2016), "Optimal Capacitor Placement in Distorted Distribution
Networks
with Different Load Models Using Penalty Free Genetic Algorithm", International Journal of
Electrical Power & Energy Systems., June, 2016. Vol. 78, pp. 174-182.
[Abstract]
[BibTeX] [DOI] [URL]
|
Abstract: Abstract Genetic Algorithm with special constraint handling procedure is proposed
for
the discrete optimization 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 to be placed on a bus. A
pair-wise
comparison in tournament selection operator is used so that it does not require any penalty
parameter
tuning, thus avoiding the most difficult aspect of the selection of appropriate penalty parameters.
Proposed Penalty Free Genetic Algorithm (PFGA) is tested on 18-bus, 69-bus and 141-bus systems and
the
obtained results are better than the results from other methods. Simulations with different load
models
are also performed. It is shown that load models where active and reactive loads are voltage
dependent,
such as residential, commercial and industrial, constant Z and constant I model lead to completely
different solutions. Therefore, careful load modeling should be put in place in order to obtain more
realistic picture of the total savings. |
BibTeX:
@article{VuleticTodorovski2016,
author = {J. Vuletić and M. Todorovski},
title = {Optimal Capacitor Placement in Distorted Distribution Networks with Different Load Models Using Penalty Free Genetic Algorithm},
journal = {International Journal of Electrical Power & Energy Systems},
year = {2016},
volume = {78},
pages = {174-182},
url = {http://dx.doi.org/10.1016/j.ijepes.2015.11.065},
doi = {10.1016/j.ijepes.2015.11.065}
}
|
Angelov J, Vuletić J, Ačkovski R and Todorovski M (2015), "An Extension in Cable Modeling for
Grounding System", IEEE Transactions on Industry Applications., Nov.-Dec., 2015. Vol. 51(6),
pp.
5086-5094.
[Abstract]
[BibTeX] [DOI] [URL]
|
Abstract: 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 π
circuits. In this paper, we focus on underground single-core cable lines with a ground return wire,
which are very common elements in distribution networks. We model the cable line as a four-phase
distributed parameter line and take into account all self-impedance and mutual impedance of three
cable
sheaths and the ground return wire. In the model, we allow for variable earth resistivity along the
cable path and cases with the ground return wire placed in full cable length or in a portion of it.
The
developed π-equivalent circuit is nonsymmetric, which is a step forward in cable modeling for
grounding
systems analysis. We have analyzed a simple distribution system where we have shown that, with the
use
of π-equivalent circuits, we can easily calculate voltages in grounding systems. The proposed
methodology offers a possibility to calculate voltage and current distribution along the cable line
in
all four conductors. The results show that costs savings are possible if the ground return wire is
not
laid in full cable length. The length of the ground return wire is determined so that the voltage
magnitude safety levels are not violated. |
BibTeX:
@article{AngelovVuleticEtAl2015,
author = {J. Angelov and J. Vuletić and R. Ačkovski and M. Todorovski},
title = {An Extension in Cable Modeling for Grounding System},
journal = {IEEE Transactions on Industry Applications},
year = {2015},
volume = {51},
number = {6},
pages = {5086-5094},
url = {http://dx.doi.org/10.1109/TIA.2015.2409807},
doi = {TIA.2015.2409807}
}
|
Rajičić D and Todorovski M (2015), "Two-Component Current Waveform for Lightning Simulation",
IEEE Transactions on Electromagnetic Compatibility., October, 2015. Vol. 57(5), pp. 1062-1069.
[Abstract]
[BibTeX] [DOI] [URL]
|
Abstract: 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 (fast
rise and slow decay). Experimental measurement differentiates three segments in the rising portion:
1)
increasing rate of rise, 2) relatively constant rate of rise, and 3) decreasing rate of rise. We
propose
two functions to represent the return stroke current waveshape, which closely resemble the first and
the
third segments, and compare them with previously developed models. In fact, we develop two versions
of
the proposed model: 1) version A: which creates waveshapes close to the waveshapes obtained by the
model
given in International Standard IEC 62305-1, and 2) version B: which creates waveshapes more similar
to
the mean waveshapes obtained by the measurement. It is worth pointing out that in both versions we
can
calculate model parameters using simple formulas. |
BibTeX:
@article{RajicicTodorovski2015,
author = {D. Rajičić and M. Todorovski},
title = {Two-Component Current Waveform for Lightning Simulation},
journal = {IEEE Transactions on Electromagnetic Compatibility},
year = {2015},
volume = {57},
number = {5},
pages = {1062-1069},
url = {http://dx.doi.org/10.1109/TEMC.2015.2420581},
doi = {10.1109/TEMC.2015.2420581}
}
|
Zdraveski V, Todorovski M and Kocarev L (2015), "Dynamic Intelligent Load Balancing in Power
Distribution Networks", International Journal of Electrical Power & Energy Systems.,
December, 2015. Vol. 73, pp. 157-261.
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: Using 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 of a PDN, without essential changes to the
last-line power installation. We present the DILB-extended PDN architecture, the algorithm itself as
well as the results of the simulation on the well known IEEE 34-Bus, 37-Bus and 123-Bus networks
that
confirm the expected level of active power losses minimization. |
BibTeX:
@article{ZdraveskiTodorovskiEtAl2015,
author = {V. Zdraveski and M. Todorovski and L. Kocarev},
title = {Dynamic Intelligent Load Balancing in Power Distribution Networks},
journal = {International Journal of Electrical Power & Energy Systems},
year = {2015},
volume = {73},
pages = {157-261},
url = {http://dx.doi.org/10.1016/j.ijepes.2015.05.012},
doi = {10.1016/j.ijepes.2015.05.012}
}
|
Gajduk A, Todorovski M and Kocarev L (2014), "Stability of power grids: an overview",
European
Physical Journal - Special Topics., June, 2014. Vol. 223, pp. 2387-2409.
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: 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 attraction: time-simulations, extended Lyapunov function, and
sum
of squares optimization method. We discuss steady state stability in power systems, and present an
example of a feedback control via a communication network for the 10 Unit 39 Bus New England Test
system. |
BibTeX:
@article{GajdukTodorovskiEtAl2014,
author = {A. Gajduk and M. Todorovski and Ljupco Kocarev},
title = {Stability of power grids: an overview},
journal = {European Physical Journal - Special Topics},
year = {2014},
volume = {223},
pages = {2387-2409},
url = {http://dx.doi.org/10.1140/epjst/e2014-02212-1},
doi = {10.1140/epjst/e2014-02212-1}
}
|
Gajduk A, Todorovski M, Kurths J and Kocarev L (2014), "Improving power grid transient stability
by
plug-in electric vehicles", New Journal of Physics., November, 2014. Vol. 16
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: 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 devices. It has been documented that PEVs serving as V2G systems can offer possible
backup for renewable power sources, can provide reactive power support, active power regulation,
load
balancing, peak load shaving, can reduce utility operating costs and can generate revenue. Here we
show
that PEVs can even improve power grid transient stability, that is, stability when the power grid is
subjected to large disturbances, including bus faults, generator and branch tripping, and sudden
large
load changes. A control strategy that regulates the power output of a fleet of PEVs based on the
speed
of generator turbines is proposed and tested on the New England 10-unit 39-bus power system. By
regulating the power output of the PEVs we show that (1) speed and voltage fluctuations resulting
from
large disturbances can be significantly reduced up to five times, and (2) the critical clearing time
can
be extended by 20–40%. Overall, the PEVs control strategy makes the power grid more robust. |
BibTeX:
@article{GajdukTodorovskiEtAl2014a,
author = {A. Gajduk and M. Todorovski and J. Kurths and L. Kocarev},
title = {Improving power grid transient stability by plug-in electric vehicles},
journal = {New Journal of Physics},
year = {2014},
volume = {16},
url = {http://dx.doi.org/10.1088/1367-2630/16/11/115011},
doi = {10.1088/1367-2630/16/11/115011}
}
|
Todorovski M (2014), "Transformer Voltage Regulation – Compact Expression Dependent on Tap
Position
and Primary/Secondary Voltage", IEEE Transactions on Power Delivery., June, 2014. Vol.
29(3),
pp. 1516-1517.
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: 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 the
primary/secondary voltage variation has a certain influence on the results which were not taken into
account in previous compact forms of the voltage regulation expression. |
BibTeX:
@article{Todorovski2014,
author = {M. Todorovski},
title = {Transformer Voltage Regulation – Compact Expression Dependent on Tap Position and Primary/Secondary Voltage},
journal = {IEEE Transactions on Power Delivery},
year = {2014},
volume = {29},
number = {3},
pages = {1516-1517},
url = {http://dx.doi.org/10.1109/TPWRD.2014.2311959},
doi = {10.1109/TPWRD.2014.2311959}
}
|
Todorovski M and Ačkovski R (2014), "Reduction of PTDF Matrix and Its Application in DC Optimal
Power
Flow", International Transactions on Electrical Energy Systems., April, 2014.
[Abstract]
[BibTeX] [DOI] [URL]
|
Abstract: The paper presents an approach where traditional Power Transfer Distribution
Factors
(PTDF) 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 number of columns in branch flow constraints
matrix. Furthermore, the number of rows is also reduced on the basis of a simple check, which
effectively detects non-binding branch flow limits allowing corresponding rows of the matrix to be
omitted. The reduced PTDF matrix was successfully applied in solving two direct current optimal
power
flow problems: cost minimization and total transfer capacity calculation. |
BibTeX:
@article{TodorovskiAckovski2014,
author = {M. Todorovski and R. Ačkovski},
title = {Reduction of PTDF Matrix and Its Application in DC Optimal Power Flow},
journal = {International Transactions on Electrical Energy Systems},
year = {2014},
url = {http://dx.doi.org/10.1002/etep.1936},
doi = {10.1002/etep.1936}
}
|
Todorovski M and Ačkovski R (2014), "Equivalent Circuit of Single-Core Cable Lines Suitable for
Grounding Systems Analysis under Line to Ground Faults", IEEE Transactions on Power
Delivery.,
April, 2014. Vol. 29(2), pp. 751-759.
[Abstract] [BibTeX] [DOI] [URL]
|
Abstract: 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 π-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 was discretized and an analytical approach
is
based on the wave propagation theory. A series of tests has been performed to determine error levels
in
both cases showing that they are less than 1%. With numerical examples, we show that the cable
equivalent circuit offers a simple way to calculate voltages in complex grounding systems. The
results
are in good agreement with the previously published calculated and/or measured values. Both
approaches
offer the possibility of calculating voltage and current distribution along the cable line which
gives
insight into the significance of each cable component in the complex grounding system. |
BibTeX:
@article{TodorovskiAckovski2014a,
author = {M. Todorovski and R. Ačkovski},
title = {Equivalent Circuit of Single-Core Cable Lines Suitable for Grounding Systems Analysis under Line to Ground Faults},
journal = {IEEE Transactions on Power Delivery},
year = {2014},
volume = {29},
number = {2},
pages = {751-759},
url = {http://dx.doi.org/10.1109/TPWRD.2013.2277887},
doi = {10.1109/TPWRD.2013.2277887}
}
|
Vuletić J and Todorovski M (2014), "Optimal Capacitor Placement in Radial Distribution Systems
Using
Clustering Based Optimization", International Journal of Electrical Power & Energy
Systems.,
November, 2014. Vol. 62, pp. 229-236.
[Abstract]
[BibTeX] [DOI] [URL]
|
Abstract: 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 network buses and places capacitors at
locations that yield maximum reduction of losses in the objective function. The effectiveness of the
proposed approach is demonstrated on a 22-bus, 34-bus, 69-bus and 85-bus distribution systems. The
CBO
results are better than the results from other methods from recent papers which include: Fuzzy
Genetic
Algorithm (FGA), Direct Search Algorithm (DSA), Teaching Learning Based Optimization (TLBO), Cuckoo
Search (CS), Self Adaptive Harmony Search Algorithm (SAHSA) and Artificial Bee Colony (ABC). In
addition, for all cases, the proposed method gives repetitive and unique results in significantly
shorter computation time. |
BibTeX:
@article{VuleticTodorovski2014,
author = {J. Vuletić and M. Todorovski},
title = {Optimal Capacitor Placement in Radial Distribution Systems Using Clustering Based Optimization},
journal = {International Journal of Electrical Power & Energy Systems},
year = {2014},
volume = {62},
pages = {229-236},
url = {http://dx.doi.org/10.1016/j.ijepes.2014.05.001},
doi = {j.ijepes.2014.05.001}
}
|
Todorovski M and Rajičić D (2006), "An Initialization Procedure in Solving Optimal Power Flow by
Genetic Algorithm", IEEE Transaction on Power Systems. Vol. 21(2), pp. 480-487.
[Abstract]
[BibTeX] [DOI] [URL]
|
Abstract: 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 overcome these difficulties, a new
procedure
for selection of an initial set of complex voltages at generator-buses is proposed in this paper.
With
this procedure, one can start the optimization process (i.e., genetic algorithm) with a set of
control
variables, causing few or no violations of constraints. The application of voltage angles at
generator-buses as control variables and the proposed initialization procedure is illustrated on the
IEEE test systems. The obtained results are analyzed and compared with the results from the
literature.
They are competitive, with computational time drastically reduced. |
BibTeX:
@article{TodorovskiRajicic2006,
author = {M. Todorovski and D. Rajičić},
title = {An Initialization Procedure in Solving Optimal Power Flow by Genetic Algorithm},
journal = {IEEE Transaction on Power Systems},
year = {2006},
volume = {21},
number = {2},
pages = {480-487},
url = {http://dx.doi.org/10.1109/TPWRS.2006.873120},
doi = {10.1109/TPWRS.2006.873120}
}
|
Todorovski M and Rajičić D (2003), "Handling Three-Winding Transformers and Loads in Short
Circuit
Analysis by the Admittance Summation Method", IEEE Transaction on Power Systems., August,
2003.
Vol. 18(3), pp. 993-1000.
[Abstract]
[BibTeX] [DOI] [URL]
|
Abstract: 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 in that approach. For
that
reason, the corresponding equations have been developed in this paper along with a procedure for
development of a three-winding transformer admittance matrix. In addition, a procedure for handling
an
arbitrary load was proposed. A large number of tests were performed and results were compared with
that
obtained by the previously published method. As an illustration, some of the results for single
fault
currents are presented. It can be concluded that the proposed approach makes the admittance
summation
method capable to take into account all network elements in a proper way. |
BibTeX:
@article{TodorovskiRajicic2003,
author = {M. Todorovski and D. Rajičić},
title = {Handling Three-Winding Transformers and Loads in Short Circuit Analysis by the Admittance Summation Method},
journal = {IEEE Transaction on Power Systems},
year = {2003},
volume = {18},
number = {3},
pages = {993-1000},
url = {http://dx.doi.org/10.1109/TPWRS.2003.814850},
doi = {10.1109/TPWRS.2003.814850}
}
|