The paper presents a power control scheme for grid-tied multilevel cascade inverter with L grid filter and modern predictive current control technique. The reference current for current predictive controller is based on the required active and reactive power supplied to the grid. The reference current is generated using instantaneous power theory (p-q theory). The behaviour of the system is simulated for different values of grid filter inductance and thus different grid current distortions. The quality of proposed control scheme is evaluated as p-q theory was originally designed for three-phase active power compensators and can not be considered as general power theory. The main advantage of proposed control scheme is its simplicity and fast response even with lower switching frequency. Predictive controller enables the control to be designed in stationary reference frame without the need of resonant current controller and PWM modulator.

This article discusses about the issues of increasing loadability in power system (PS) by using FACTS (Flexible Alternating Current Transmission System) devices, while reducing active power losses that occur in the transmission of power in the network. For this purpose we used two types of FACTS devices. It is a TCSC (Thyristor Controlled Series Capacitor) and SVC (Static Var Compensator). All simulations were performed in Matlab program.

This paper deals with measuring of shielding effectiveness of electromagnetic field. The measurements were focused on shielding effectiveness while gradually drying out building materials in the range of high frequencies from 1 GHz to 13 GHz. The measured object was fiber cement board facade Eterplan and exterior facade board Natura Pro. Thickness of the boards were 8 mm. The measurement should prove that the shielding effectiveness of electromagnetic field of the wet materials is higher than the dry materials.

The paper deals with hardware design for sensoric subsystem of a small helicopter model and in real time generates data about helicopter state variables during helicopter flight. The main unit for data processing presents an embedded computer built on a mini- ITX motherboard with processor Intel i3. As the helicopter presents a system with six degrees of freedom and in the fact, during the flight, there is not any fixed point that would enable to calibre the sensors placed on the helicopter board, for processing of sensor data Kalman filter is necessary.

The aim of this paper is to show that disinfection system using ozone generated by dielectric barrier discharge (DBD) is an effective alternative to be used in food industry and ensures a safe quality of air for optimum preservation of fruits and vegetables. The DBDs are specific kind of discharges because one (or sometimes both electrodes) is covered by a dielectric material, thereby preventing the discharge to move towards electrical breakdown. A succession of micro-discharges occurs rapidly; their "lifetime" is in the range of a few nanoseconds. One of their most important applications is the production of ozone for air treatment, used mainly in the area of food industry, for extending the storage life of foods. After the achievement of a surface DBD reactor of cylindrical shape and its electrical characterization, it was then used as an ozone generator for air disinfection. Obtained results have shown that this reactor used as an ozone generator is effective for disinfection of air by removing viruses, bacteria and pathogens, causing the slowdown of the ripening process of fruits andvegetables.

This paper presents a novel and simple vector control algorithm for induction motor drives. The classical vector control and direct torque control algorithms give the decoupled control. But, the classical vector control algorithm uses reference frame transformation, which increases the complexity of the algorithm for implementation. Whereas the direct torque control is simple for the implementation by using the lookup tables approach, but, it gives large steady state ripple in torque, flux and current. Hence, to overcome the drawbacks of both vector control and direct torque control, the proposed method combines the principles of both vector control and direct torque control. In the proposed algorithm, the d- and q-axes reference currents are generated as per the principles of vector control algorithm and vector based hysteresis comparators integrated with look-up tables are used as per the principle of direct torque control. Moreover, to reduce the torque ripple, a novel constant switching frequency current controller is proposed. To validate the proposed method numerical simulations have been carried out and compared with the existing algorithms. The simulation results show the effectiveness of the proposed technique.

Photovoltaic power plants are sources of electrical energy that are dependent on weather conditions. Consequences include their stochastic change of the production power. The survey focus on assess the impact of photovoltaic power plants operation on the daily load diagram with regard to output change difference of active power. Statistical methods have been employed to process a methodology in order establish extreme conditions of production power for photovoltaic power plant. The already evaluated minimum and maximum extreme conditions are applied to the daily load diagram. Evaluation is based on real-time synchronous data measuring both on-site photovoltaic power plant operation and on-site electric power line output from the substation, where the power plant is connected. This paper describes the methodology for determining the difference in the change of active power at the power line output from the substation to ensure loads in this location.

Present paper shows that even seemingly acceptable linearization of the mathematical model of harmonically excited nonlinear magnetic circuit may lead to appreciable errors.

Using solar energy in photovoltaic power plants is an important method of electricity generation from renewable energy sources. Its potential is vast and technically easy to utilise. The rapid development of photovoltaic sources is having a negative effect on the electric power system control. One option for mitigating this effect is to store the energy generated by photovoltaic in times of excess power in the grid and supply it to the grid when required, i.e., during peak periods of the daily load curve. Photovoltaic power plants in connexion with a hydrogen storage system seems very promising as a sources of electric power in an island (off-grid) systems. This paper describes our research into solar energy storage using hydrogen technologies in the case of off-grid systems. Storage in hydrogen as an energy carrier is currently the focus of intensive research in many research centres.

This paper presents a simple and novel carrier based unified pulse width modulation (UPWM) algorithm for voltage source inverter (VSI) fed AC drives. To reduce the complexity involved in the existing PWM algorithms due to angle and sector information, the proposed UPWM algorithm uses the notion of imaginary switching times, which uses the instantaneous phase voltages only. To validate the proposed algorithm at all modulation indices, a simple over modulation algorithm is also presented in this paper. By varying the offset time in the proposed UPWM algorithm various continuous PWM (CPWM) algorithms like sinusoidal PWM (SPWM) and space vector PWM (SVPWM) and discontinuous PWM (DPWM) algorithms such as DPWMMIN, DPWMMAX, DPWM0, DPWM1, DPWM2 and DPWM3 can be generated at all modulation indices. To verify the proposed UPWM algorithm, numerical simulation studies have been carried out and results are presented.

There are known several exact results of the crossing numbers of the Cartesian product of all graphs of order at most four with paths, cycles and stars. Moreover, for the path P_n of length n, the crossing numbers of Cartesian products GP_n for all connected graphs G on five vertices and for forty graphs G on six vertices are given. In the paper, we extend these results by determining the crossing numbers for the Cartesian products of paths with two special graphs of order six.