This work focuses on the use of a one-phase direct current (DC) power supply equipped with a shunt active filter feature, which enabled the possibility of compensation (minimisation) of reactive and distortion power, generated by a group of loads, that was connected to the same power grid node as the power supply. A tuned inductor, which was included at the input of the controlled current source (constituting the main part of the power supply) allowed for an improvement in the quality of the compensation process, compared to a device with a fixed inductive filter This resulted in a visible reduction of the nonlinear distortions of the grid current. The improvement was made possible by extending the frequency response of the current source, which allowed to increase the dynamics of the current changes at the input of the power supply. This solution represents a new approach to such power devices. This work describes the principle of operation of the proposed converter solution and presents selected test results for a laboratory model of an electric system with this device.

Calculating the values of the parameters of distorted periodic signals in real-time is important for the control of many processes. In particular, this information is necessary for the proper operation of power electronics devices that cooperate with the power grid. In such cases, it is necessary to determine the phase, frequency, and amplitude of the fundamental component of the voltage in the power grid node. Also, in many cases, the control process needs a signal which is synchronised with the power grid voltage. Both processes should be realised in real-time. A number of solutions to the problem of calculating the values of the voltage parameters have been described in the literature. However, these methods generally introduce significant time delays and have several restrictions regarding the variability in the values of these parameters. They also often require the significant computational power of a unit that performs the task of identification. The algorithm presented in this work is based on the properties of a pair of orthogonal signals, generated by a two-dimensional finite impulse response filter, which has a certain transfer function resulting from the needs of the algorithm, what is the innovation of the algorithm. These signals are then used in the program module, which both, calculates, in the time domain, the instantaneous values of the frequency and the amplitude of the fundamental component of the power grid voltage, and generates a signal, being in-phase with this component. The presented algorithm is fast, accurate, and relatively simple; therefore, it does not require a high computational power processor. This algorithm was experimentally verified by implementation in microcomputer-based units, which were then applied in the control systems of the power electronic devices, as well as in analysers of the energy quality.

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The work presents a DC power supply with power factor correction (PFC). This device is also equipped with a parallel active filter function, which enables the possibility of compensation (minimization) of reactive and distortion power, generated by a group of loads, connected to the same power grid node. A passive filter with variable inductance applied at the input of the power supply allows for a significant improvement in quality of the system control (given specific criteria), as compared to the solution with a filter with fixed parameters. This is possible by increasing the dynamics of current changes at the power supply input (extending its "frequency response"). The paper presents the principle of operation as well as structures and models of the power supply control system and its power stage. Selected test results of the simulation model of the electric system with the power supply, in various operating conditions, are also presented.

This paper presents a concept of a shunt active power filter, which is able to provide more precise mapping of its input current drawn from a power line in a reference signal, as compared to a typical filter solution. It can be achieved by means of an interconnection of two separate power electronics converters making, as a whole, a controlled current source, which mainly determines the quality of the shunt active filter operation. One of these power devices, the "auxiliary converter", corrects the total output current, being a sum of output currents of both converters, toward the reference signal. The rated output power of the auxiliary converter is much lower than the output power of the main one, while its frequency response is extended. Thanks to both these properties and the operation of the auxiliary converter in a continuous mode, pulse modulation components in the filter input current are minimized. Benefits of the filter are paid for by a relatively small increase in the complexity and cost of the system. The proposed solution can be especially attractive for devices with higher output power, where, due to dynamic power loss in power switches, a pulse modulation carrier frequency must be lowered, leading to the limitation of the "frequency response" of the converter. The concept of such a system was called the "hybrid converter topology". In the first part of the paper, the rules of operation of the active filter based on this topology are presented. Also, the results of comparative studies of filter simulation models based on both typical, i.e. single converter, and hybrid converter topologies, are discussed.