Michał Rodak

The use of advanced switching technologies, including hybrid and fully semiconductor-based circuit breakers, enables a significant reduction in the prospective short-circuit current. This enhances the level of circuit protection by minimizing thermal and electrodynamic stresses. One of the available solutions is a hybrid DC circuit breaker employing the forced commutation method, in which a counter-current generator is incorporated into the auxiliary branch. Increasing requirements not only for short-circuit protection reliability but also for operational flexibility impose the need to configure DC breakers for parallel operation. This paper presents an analysis of the performance of forced-commutation circuit breakers connected in parallel with another identical device, as well as with a conventional fast magnetic blow-out breaker. To prevent unintended and undesired tripping, the influence of counter-current generator parameters on the overcurrent protection response was investigated. In the analyzed configuration, the applied hybrid DC breaker limits the expected short-circuit current from approximately 45 kA to 5 kA within about 2 ms.

The use of vacuum-hybrid DC circuit breaking methods allows the short-circuit current to be switched off in a shorter time, resulting in a reduction in the arc burning time. This requires the use of a drive, such as the Thomson Coil Actuator TCA, capable of providing a short response time for opening the vacuum interrupter VI, regardless of its rated current. The IDD is powered by a pre-charged capacitor, which, together with the drive coil, forms an LC oscillating circuit that, when switched on by a thyristor, generates a current pulse of several kA with a frequency above 1 kHz. The paper investigates the effect of modifying the basic IDD power supply circuit by adding semiconductor diodes to shape the current pulse and improve its performance. The authors also focused on exploring the impact of the connection quality and their length and the associated loss in drive force while proving that a circuit with a reverse diode on the IDD coil is most beneficial and that the effect of the circuit on the front of the current pulse can significantly slow down the drive.

This article presents the universal inductive-dynamic drive (IDD) that operates in two different vacuum contact units (VCUs), for 600 A and 2 kA. The new VCUs are the crucial components used in dc hybrid switches (DCHSs) which are part of an energy extraction system (EES) aimed at protecting superconducting circuits at CERN. The use of IDD in these switches, thanks to its response time of less than 300 μs, makes it possible to carry out the switching process in 1.5 ms while satisfying the high reliability requirements of the devices. The article presents, for the first time, ways of modifying the parameters of IDD and their effect on the generated repulsive force and response time, which is a crucial parameter for introduced DCHSs operating based on forced commutation and natural commutation methods. The conducted research proves that IDD with the same parameters can be applied as a universal drive capable of operating in hybrid switches rated for a wide range of currents.

The article provides an overview of Brain Computer Interface (BCI) solutions for intelligent buildings. A significant topic from the smart cities point of view. That solution could be implemented as one of the human-building interfaces. The authors presented an analysis of the use of BCI in specific building systems. The article presents an analysis of BCI solutions in the context of controlling devices/systems included in the Building Management System (BMS). The Article confirms the possibility of using this method of communication between the user and the building’s central unit. Despite many confirmations of repeatable device inspections, the article presents the challenges faced by the commercialization of the solution in buildings.

The article presents a new family of low voltage dc switching energy extraction (EES) systems designed for protection of superconducting magnet circuits at CERN, which is appropriate also in other applications. During normal operation, superconducting magnet circuits can store large amounts of energy in their magnetic fields. In the case of a resistive transition (known as “quench”), this energy may be dangerous as it can lead to high temperatures and voltages, eventually damaging the superconducting magnet coils. To prevent this, the magnetic energy must be extracted and dissipated outside the superconducting windings. For this purpose, dedicated energy absorbers are introduced in the circuit by means of opening of dc switches. For the protection of future superconducting magnet circuits at CERN, direct current switching systems (DCSS) with rated currents of 2000 and 600 A have been developed and qualified. Each DCSS is unpolarized and redundant, i.e., composed of two identical direct current switch (DCS) connected in series. Two methods for the current commutation toward the energy absorber element have been investigated, the first one based on IGBT and the second one based on thyristors. A high-power, inductive-dynamic drive provides the ultrafast opening of the vacuum interrupter in the DCS.

Advances in distributed generation and increased contribution of renewable energy source (RES) require development of smart grid technologies. Smart metering systems, as a part of smart grid technologies, in cooperation with modern buildings equipped with building management system allows for improvement of energy efficiency. It is possible to partially cover the power demand of a building from the local RESs. However, in order to ensure maximum added value, energy management system (EMS) is essential. This article presents the project and practical implementation of an EMS implemented in smart‐meter. The designed system is based on an original algorithm using fuzzy logic. The rule base was created in FCL language and the implementation was carried out in C++ with the object‐oriented programming (OOP). For the efficiency rating indicator, peak‐to‐average ratio (PAR) was selected. This ratio depending on the daily load profile decreased within a range from 15 to 54%, and the average value was 30%. The proposed energy management algorithm helps to reduce energy consumption at peak demand by 34%, with the total reduction of energy consumption during the day of 7%. The described solution demonstrates a potential for real implementation and was tested in hardware.

Wydawnictwo SIGMA-NOT wydaje czasopisma fachowe informujące swoich czytelników o najnowszych osiągnięciach naukowych i nowoczesnych rozwiązaniach technicznych w Polsce i na świecie, popularyzuje problemy techniczne oraz poszerza wiedzę i kulturę techniczną.