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These days, with the significant increase in the use of renewable energy sources as additional energy sources connected to the distribution network, many challenges and difficulties arise in ensuring sustainability and reliability. The generation, transmission and distribution, in the current state of the electricity system, are facing quite dynamic changes. They are the result of the liberalization of the energy market, the increased use of renewable energy sources such as photovoltaic systems, wind turbines and the charging stations for hybrid and electric vehicles. The most important factors are related to the balancing of the energy system, the analysis of voltage stability, overcoming the consequences of the increase in short-circuit currents, increasing the transmission capacities of the system forming and distribution networks, as well as the accurate forecasting of the development of loads and consumption over the coming years. This article presents an analysis of the voltage stability in a smart microgrid for two different scenarios. The studied cases describe a linear low-voltage p-type microgrid with loads connected to it at different nodes. Data on the type and cross-section of the conductors of the studied power line are presented. Simulation studies were carried out to determine the limits of grid voltage stability when connecting photovoltaic plants with a set power. The simulation results are commented on and an analysis of the optimal operating mode of the system is realized. The model studies were implemented in the NEPLAN program environment. The research carried out allows an evaluation of the permissible limits for network stability when connecting photovoltaic plants. Through this evaluation, it can be determined how many and at which node the loads should be connected without causing an imbalance in the network. This is useful from the point of view of ensuring the sustainability and reliability of electrical energy in a microgrid.

In current research a hybrid autonomous supplying system for electric vehicles applications is presented. The hybrid system is consisted of fuel cell, micro gas turbine and supercapacitor. There are realized with averaged models in MATLAB/Simulink environment. The supplying elements are connected to a DC bus for charging a different type of EVs. In this case as a load is use two EVs: BMW-i3 and Nissan Leaf. This system can operate autonomously in hard-to-reach places where there is no supplying from the distributed grid and other sources. These places could be remote holiday villages, research centers positioned at hard-to-reach places and also for production of agricultural crops with the aids of electric vehicles. This requires the necessity for searching of different structural and conceptual solutions for production and storage of electric energy. An optimization problem is resolved in order to reduce the value of the capacitance of the supercapacitor with which it will decrease his price. Thus, it also decreases the price for construction of the entire charging station. Recently, the usage of natural gas and his transportation is well organized which can contribute for assuring of the reserved energy for the autonomous charging station.

In the current paper is presented an examination of the innovative methods for control of electric vehicles. Principal characteristics of linearization of nonlinear system, model predictive control and neural network are proposed. The main objective of this research is to determine the important advantages and disadvantages of the different approaches for control.

In this research a mathematical model of LLC resonant converter for supplying a LEDs is studied. The differential equation in the resonant frequency, above and below resonant frequency are described. In this research the ideal case is presented. This model is realized in PowerSim environment. A simulation results of the current and output voltage of the converter are presented. On the base of the model and the obtained results it can be realized different optimization procedure, study of sustainability, tolerance analysis and control synthesis.

In the current paper a mathematical model of DC/DC Cuk converter is presented. The simulation study is developed in MATLAB/Simulink The mathematical model is described with differential equations and PI regulator. After adjustment of the PI regulator is added a NARMA L2 Controlled for optimization with neuron network. The operation of the converter is demonstrated in various disturbances. The obtained results are useful in view of their use in education and in particular in the synthesis of control.

Smart integration of the upcoming proliferation of electric forms of transport in our energy system is the key in order to make it more robust and ready for a greener future. As such, technologies as Vehicle to Home are key in order to optimize the house consumption on an individual level. This paper develops the key blocks of a modified Vehicle to Home system, where in addition to the EV, a stationary battery pack is added. The paper presents models for household consumption, bidirectional AC/DC converter, its control system, dc/dc controllers, and their controllers. The goal is to design a system capable of consuming a desired power over time from the AC grid. Any energy difference is used to charge or discharge the available energy sources. As such, optimal control strategies are developed for the control of both the charging/discharging process. The presented optimized models allow for system level simulation for several weeks on a typical computer. Using this model some allows bot sizing the dc energy storage needed, along with comparison of different control algorithms for the power converters.

In the current research modeling and simulation of a hybrid electric vehicle (HEV) in PSIM environment is presented. A review of the frequently used structure of for realization of the HEVs are proposed. Consistently, the individual stages of modeling are presented including the choice of electric motor, power electronic converters and energy storage devices. The simulation results of the most important electrical and mechanical parameters which characterized the HEVs are presented. This modeling method is very useful and suitable for the purposes of the training of the power and automotive electronics.

In the current research a model simulating a system consisting of DC-DC converter with fuel cell and supercapacitor is presented. The model is realized in MATLAB/Simulink environment. For energy storage device a supercapacitor is used. On the base of the developed model and the control system of the energy flows, a researches related with the necessary value of the supercapacitor with the basic purpose provision of the aforetime set load profile are realized. Another essential problem of the control system of the power converter is to provide operation mode with maximal efficiency of the power source – fuel cell. This research is useful for determination of the optimal value of the energy storage device, which has significantly meaning for economically efficiency of the system for decentralized production of the electrical energy.

In this research a MATLAB optimization of a boost converter is proposed. With the aid of the mathematical model created by the methodology of switching function is executed an optimization procedure with main purpose precise definition of the designed value of the passive components. The purpose of this research is to obtained aperiodic transient process in the output of the converter. This facilitates control synthesis and facilitates the setting of the controller coefficients. The specific implementation was done with the help of tools that are created in the MATLAB/ Simulink environment, which is very useful in view of the use of the proposed procedure by non-specialists in mathematics. On the other hand, as a result of the optimization, the transient time in the power circuit is shortened, which significantly improves its dynamics.

In the current research a mathematical model of DC-DC converter charging an energy storage devices is presented. The model of the converter is realized in MATLAB/Simulink. For energy storage devices is used a supercapacitor.

In the current paper a comparison between several control strategies for LED lighting application are presented. A classical method such as control with PI regulator is described. Also, several methods such as linearization, model predictive control and neural network are realized. The basic idea in this study is to find optimal solution suitable in multiple cases for control of DC-DC converters supplying LED lighting.

In this paper a mathematical modeling and optimization of the DC-DC converters are realized. Two different topologies Cuk and Zeta with their particularity are presented. The mathematical model and optimization are realized in MATLAB/Simulink environment.

In this research a mathematical model of a hybrid system with wind generator and supercapacitor for supplying a smart home is realized. The model is described with the aid of differential equations. The simulation and numerical results are presented. The model is developed in MATLAB/Simulink environment.

In the current paper a mathematical modelling of a hybrid system with fuel cell and supercapacitor for usage in LED lighting are realized. Most typical structures for supplying of the system are presented. It is used two different load schedule: for smart home and for street lighting.

In the current paper a current mode control of a buck DC-DC converter is presented. The simulation model are realized in PSIM environment. The main purposes for this research is to present the program and her possibilities for simpler understanding and studying of basic principles of control design for the students and young researchers in Power electronics.

This paper proposes a generalized switched function model for a bidirectional DC-DC converters. Typical application for such converters is as a part of an electric vehicle power topology, where different architectures are available when more than one energy source is available. For this reason the model is general enough to incorporate a cascade or a parallel power architecture. The model includes switching and conduction losses of the semiconductor devices and ESR loss of the power inductor. The load of the model is based on the load requirements for a vehicle driving a standard Cycle WLTC.

In the current paper mathematical modeling and simulation of DC/DC converter for educational purposes are presented. It is reviewed the main possibilities of modeling in PSIM environment. The main libraries and tools are described. The mathematical model of buck converter with variation of the values of the inductor and the capacitor are presented.

This paper presents a complete model of a small electric vehicle consisting of fuel cell, supercapacitor, power conversion system with its control system. This electrical system is loaded by a vehicle model that takes as input a standard vehicle test cycle (such as NEDC, WLTP or other) and translates it into current that must be supplied or consumed from the power conversion system. The model is tested with two different topologies (cascade and parallel) of the hybrid energy source. On the basis of the conducted studies, the paper compares the simulation results for different types of topologies and draws conclusions regarding their applications for different types of electric vehicles. The model allows for observation of both electrical and mechanical parameters as opposed to others available in the literature.

This paper presents a mathematical model for determination of energy cycles of electric vehicle. The main objective of this research is to create and verify the mathematical model for studying of the main physical and energy parameters during acceleration and braking operations. In the presented model the aerodynamic drag, rolling resistance and grading resistance of the road are considered. For the testing, a chassis dynamometer tests for the determination of emissions and fuel consumption are used. The simulation results are experimentally verified. The key point is that the model can be useful for evaluation of energy storage during the chassis dynamometer tests.

In the current paper an estimation of energy parameters in electric vehicles is presented. Multiple electric vehicles are examined with their characteristics. The main purposes of this article is to create comparatively simpler mathematical model for estimation of energy flow during acceleration and braking. For this reason an urban and suburban dynamometer cycles are used.

In the current paper an application of the hybrid electric vehicles as a system for supplying of a smart home is presented. This solution allows a better energy management. A main characteristics of a HEVs, smart home, types of batteries and PV systems are proposed.

In the current paper a zero voltage switch DC/DC resonant converter for LED application is proposed. The mathematical model is described with differential equations.

In the current paper an optimization of bidirectional converter for electric vehicles applications is proposed. A mathematical model of the DC/DC converter is described. The simulations are realized in MATLAB/Simulink. The optimization of the value of the passive components is the main purposes of this research.

In the current paper a mathematical modelling of SEPIC DC-DC converter is presented. A methodology with switching function is used. The realized model is implemented in MATLAB/Simulink environment. An optimization procedure for determination of the optimal value for the proposed solution is used. This model is suitable for a LED lighting applications.

In this research a comparison of control methods of a buck DC/DC converter realized with neural network NARMA and PI regulator are presented. The possibilities of this control method for function approximation are demonstrated. The paper presents a comparison between a classical and modern methods for smart control.

The paper presents a mathematical model and its experimental verification for a light vehicle. The main purpose of this study is the creation and verification of a simplified model for examining the main physical parameters during normal vehicle operation. The model presented is based on a previous original study, but here it is modified in order to minimize the error compared to the obtained experimental results. It models the aerodynamic drag, rolling resistance and grading resistance of the road as these are the primary forces that oppose the engine force. The obtained results are experimentally verified. The key areas that the model can be further improved are discussed at the end.

The present paper study modelling, design consideration and control of a bidirectional DC/DC buck-boost converter for application in hybrid and electric vehicles. The proposed model includes electric motor, dynamics of the vehicle and theirs control. A mathematical model of the DC/DC buck-boost converter is described with differential equations during the both the boost and buck regions of operation. The control system is created and realized with proportional-integral regulator. The proposed solution is realized in visual environment MATLAB/Simulink. The obtained results demonstrates that the proposed solution is suitable for different electric vehicles applications.

Nowadays, with the increasing of the pollution and global warming one of the solutions for the current problems could be resolved with the usage of electric vehicles. The development and research of the electric vehicles includes establishment of electrical and mechanical systems. The main objective is to develop a model and control system to study the energy flows in acceleration and braking modes. For the improvement of the process of design a different mathematical model is necessary to be used entire system consisting of electric motor, electronic converters, gearbox and differential. In the proposed model it is also taken into account a rolling resistance, aerodynamic drag and the force of the electric motor.

Recently, in the modern society the usage of electric vehicles is significantly growing. This has led to the necessity for studying of the bidirectional converters for optimal control of energy flows in electric vehicles. In the current paper a model of a DC/DC bidirectional converter for electric vehicles applications is developed for educational purposes.

In this paper is presented the modelling of a buck DC/DC converter with neural network controller. The possibilities of this control method for function approximation are demonstrated. The converter model is implemented in the MATLAB/Simulink environment and its operation with neural network and PI controller is studied. Simulation results highlight the advantages of neural network-based control of the DC-DC converter. The presented study of modelling and control of the power electronic converter is intended for educational purposes and student training.

In the current paper an overview of a state of art of fuel cells used in electric vehicle application is presented. A typical operation of a fuel cell is demonstrated. The main type of power production unit for supplying of electric vehicles are proposed. An analytic and technical study of the photovoltaic panel and the electrolyser is presented.

In the current paper a model of bidirectional DC/DC multi quadrant converter is developed. The proposed model is composed by a separately excited DC motor, a buck-boost converter and a proportional-integral (PI) regulator. The solution is described with the aid of system of differentials equations and realized in the visual environment MATLAB/Simulink. Two operation modes are studied: acceleration mode and braking (regenerative) mode. From the presented and discussed results it is observed that the proposed solution is suitable for hybrid electric vehicles applications with multiple energy source such as battery and supercapacitor.

In this paper is presented a test bench for research on multiple operation modes in small-scale power systems: micro-, mini and nanogrids. The hybrid system is composed of a photovoltaic simulator, a controllable AC load, a battery bank and SCADA system. The operation of the test bench is studied by five different scenarios in grid-connected and standalone modes. The presented test bench can be used for testing and standardization of grid-connected and standalone inverters, MPPT trackers, research on the stability of small-scale power systems and for educational purposes in the corresponding courses.

This paper describes a new physical model for micro-, mini- and nanogrid research and testing, which has been developed and realized at the Power System Stability Laboratory (PSSL) of the Technical University - Sofia. Created to be flexible, the model allows for an investigation of various configurations and schemes performed in different test scenarios. It allows for a variety of physical tests focused on power system stability studies, micro- and nanogrid control, distribution grid and bulk power system control solutions, distributed generation, load and electrical vehicles control strategies, electronic power converter solutions testing, etc.

The environmental challenges and population growth come as evidence of the importance of thinking about other means of production, while maintaining the safety and reliability of the electrical system. As far as the charges are concerned, we can predict the appearance of a new type: electric vehicles. Simultaneous charging of multiple electric vehicles in a distribution network can result in a significant load. The main purpose in this paper is to examine a novel method for optimal control of energy flows between the distribution network and multiple electric vehicles (EV). A specialized software - LINDO is used for solving the optimization problem.

The boost converter are the most commonly used DC/DC converters, especially for automotive applications, power amplifier applications, adaptive control applications, battery power systems, consumer electronics and communication applications. This is because the battery charge requires high DC voltage to be fully charged. The main object of the research in the current paper is to examine the operation of the boost converter in visual programing environments like Matlab and LabVIEW. A mathematical model of the converter and its parameters are presented. The simulation results states that Matlab/Simulink is a suitable platform for control and regulation of the simulation processes, in additional to its dominant role in conducting research tasks. Similarly, LabVIEW software provides the possibility to be used for application that requires test, measurement and control with rapid access to hardware and data insights.

To control a smart grid in stationary application or in an embedded application such as electric vehicles, it is needful to comprehend behavior and modelling of the energy storage devices. In this article a simple electrical model for describing charging process of a supercapacitor for usage in electric vehicles applications is depict. Three scenarios with three equivalent scheme are proposed. The studied models are realized in the MATLAB/Simulink environment. The models and the simulation results of the supercapacitor are compared and analyzed.

The modelling and control of a DC-coupled hybrid system composed of a micro gas turbine and supercapacitor energy storage bank is presented in this paper. The supercapacitor is used for short power balancing in order to achieve constant power at the system output until the micro gas turbine reacts to the load change. The corresponding control system for power references setting and control of the converters has been developed. The hybrid system is modeled and implemented in MATLAB/Simulink. Simulation results demonstrate proper operation of the proposed hybrid system and its control – at the moment when an electric vehicle is plugged in to the system, the required power for fast charge is provided. In this way fast recharging of electric vehicles can be performed at remote gas stations without further reinforcement of the existing power distribution infrastructure.

This paper presents test evaluation and experimental results from the implementation of the approach for smart active power management in micro and nanogrids given in [1–4] under island and grid-connected mode. A new power electronic smart load controller for improving the power system stability and active power management is proposed and realized. The controller interaction is tested in a "power hardware in the loop" test performed at the Power System Stability Laboratory of TU-Sofia. The analysis of the results proves the functionality of the proposed concept and hardware realization. The approach offers cost effective solution to the main issues related to normal and stable micro and nanogrid operation.