The rapid development of technology allows designing better and better filter systems. Active filters are more and more often used. They also have their drawbacks, including their price. Passive filters are still very often used. However, despite the passing years, for some filter structures, optimal design equations were not derived that take into account the equivalent impedance of the main and the filters detuning. This article presents an analysis of a double-tuned filter and the analytical maximization of harmonic reduction based on the location of the maximum impedance filter characteristics and the replacement impedance of the mains, which mainly determine the efficiency of filtration. Filter detuning from reduced harmonics is also considered. Formulae have been determined to design the optimal double-tuned filter as well as to design a filter with the assumed degree of reduction of one of the harmonics. The impact of incorporating the resistances of filter elements and of the mains into the analysis on the accuracy of the designated solution was also examined.

Single-branch filters are still popular and are commonly used for power quality improvement purposes. Analysis of a single-branch filter is a relatively simple task. Although individual filters tuned to specific harmonics can be easily designed, after connecting them into a group it turns out that the capacitance and inductance mutually influence each other, distorting the resulting frequency characteristics. This article presents a matrix method for design a group of single-branch filters, so that the resultant frequency characteristic satisfies the design requirements including the requirements for location of the frequency characteristic maxima. Designer indicates the frequencies of the parallel resonances

On the basis of the current trends for solving complex technical problems, a new concept of power quality improvement is proposed. It consists in creating a distributed system for supply conditions improvement in a given islanding power system, in e.g. geographical terms (with determined points of delivery), or as an internal installation system of an industrial consumer.

This article presents the results of measuring P_st indicators at three points of a power system supplying a large source of voltage disturbances—an arc furnace. Measurements were made at three voltage levels: 30, 110, and 400 kV. Recorded values of P_st at each point were subjected to statistical analysis, the probability distributions were adjusted to their histograms, and the nature of changes in the basic parameters of these distributions with the distance from the source of disturbances was indicated. The adjustments of the distributions were made using a modified firefly algorithm.

A continuous development of technology involves a permanent improvement of appliances towards the increase in energy effectiveness, efficiency and precision of operation. This applies ...