The paper presents the study of a three-phase system coupling a DC power source to a power grid. This study, based on an FPGA, implements a real-time control system and digital models of the power circuit. The proposed proportional–resonant (P+R) controller with a modified structure was part of the system, which can be used as an alternative controller to traditional ones, e.g., in photovoltaic systems. Due to difficulties in implementing resonant controllers, a P+R with a new structure using a PI controller was elaborated. With an appropriate approach to the generation of phase current patterns, it is possible to set the reactive current and, thus, compensate for the reactive power. The operation of the system for typical operating conditions (e.g., system startup, change in preset load) was characterized and compared with a classical solution using a PI controller.

The theoretical and practical aspects and results of simulations based on a specialized tool that is used in the energy industry were adressed. The previously discussed cases in the literature by taking into account the worst case and critical states of networks in terms of complex networks were extended. Using the Monte-Carlo method, the vulnerability of the power grid to node failures was investigated, both in terms of the use of specialized software, which is used in the power industry, and a tool for the analysis of complex networks graphs. We present the results obtained and the observed analogy between the results of the analysis performed in specialized software and the complex network graph analysis tool. It has been shown that the results obtained coincide for both software packages, even though their application focuses on slightly different aspects of system operation. Moreover, further possibilities of extending the research in this direction are proposed, taking into account not only the improvement of the method used, but also a significant increase in the size of the tested structure model.

The analyses of the influence of spatial harmonics on the electromagnetic torque of the multi-phase induction machine and reducing this influence are important tasks to ensure the high efficiency of the induction machine. Designing the machine to consider the influence of spatial harmonics is essential to ensure the desired mechanical and energy characteristics. In the case of the sinusoidal winding supply of the induction machine, the magnetomotive force has high spatial harmonics, which are caused by the machine-winding design. The interaction between the 5th, 7th, 11th and 13th spatial harmonics of the winding function and the first time-harmonic of the winding supply causes the appearance of the 6th and 12th harmonics in the electromagnetic torque of the machine. A prototype of the symmetrical six-phase induction machine and the experimental study for the influence of spatial harmonics on the harmonic content of the stator currents in different machine modes are given in this paper. The mathematical model of the six-phase induction machine has been developed using the average voltages in integration step method. The introduction of the harmonic components into the magnetization inductance in the mathematical model of the six-phase induction machine for taking into account the spatial harmonics of the machine-winding function is proposed in this paper. The adequacy of the mathematical model was confirmed by comparing the simulation and experimental results. The harmonic content of the electromagnetic torque, which is caused by spatial harmonic influence, is analyzed.

The article deals with the subject of the influence of a selected wind farm, located in the south-east part of Poland, on electrical power quality, in a power system. The measurements, which were obtained with a power quality analyzer, were analyzed and compared with acceptable values, from appropriate standardization documents.

The size reduction in on-board apparatuses in flying platforms, ships, and aerospace vehicles can be achieved by increasing the frequency of the on-board grid voltage. In the case of renewable powered platforms, a grid converter is used that has the primary task of feeding the generated energy into the on-board grid. The paper describes the developed control system of the grid converter, which, in addition to transferring the generated power to the single-phase grid, effectively compensates the reactive power occurring in it. The proposed structure of the proportional resonant regulator with finite gain that cooperates with the single-phase grid was discussed. The use of quadrature estimators of voltage and current enabled independent control of the active and reactive components of the current, thus compensating for the reactive power. The proposed control system structure was implemented on the FPGA platform and experimentally tested in steady state and dynamic condition considering grid disturbances and solar irradiance variations.

The paper focuses on the parameters of electricity power quality in the power grid at the level of 110 kV. One of the latest revisions of the PN-EN 50160 standard expands the area of its application to the high voltages. Because of that, tests were done to determine the main parameters of power quality at the point of delivery of the electricity to the customer at 110 kV voltage level. Obtained results, with power quality analyser help, were analysed and compared with the limits contained in the relevant standardization documents.