on the series connection of power modules using standard low-voltage components. It allows for low THD output voltages and input currents, reduction of passive components and redundancy of components. Thanks to these features, the cascaded multilevel converters have been recognized as attractive solutions for HVDC transmission, SST and photovoltaic (PV) systems. The timely problem of how to interface different types of energy storages with power grid is addressed by an exceptionally experienced team of specialists: A. Domino, K. Zymmer and M. Parchomiuk from the Electrotechnical Institute (IEL), Warsaw, Poland [5]. They present an overview of converter topologies for energy storage, such as superconducting magnetic energy storage (SMES), supercapacitor energy storage (SES) and chemical batteries. Tech. 59 (4), 2011. The newest Special Section is intended to focus on recent research and trends in application of multilevel converters. Multilevel converters have been extensively developed over the last two decades and show several important advantages of power electronic circuits, such as: operation at high voltages, harmonics reduction, higher efficiency, modularity, smaller size and lower cost. Also, thanks to increasing interest in renewable energy systems (RES) and SGs, the development of multilevel converters is considerably accelerated. The papers included in the presented special section are grouped into the main categories that follow. . Some limitations on application of such inverters for precision drive control in optical telescopes were specified. Modern predictive control methods developed for Special issue of high power multilevel converters [11-15].The design and investigation results of switched capacitor voltage multipliers for application in high power systems is presented by the team of outstanding specialists from AGH University of Science and Technology, Krakow, Poland [11]. The considered family of multilevel converters includes classical topologies and also novel concepts. The application of thyristors as well as invention of novel concepts of multiplier topologies with appropriate control make it possible to achieve high efficiency, high voltage gain, as well as reliable and simple DC-DC converters for high power systems. The fundamental problem of how to increase the DC fault ride-through capability of a full-bridge modular multilevel converter (MMC) station while ensuring a stable controlled operation as a STATCOM during DC faults without the need for fault isolation is deeply discussed and well illustrated by the international team of excellent researchers E. Kontos, and P. Technology, Poland, the control strategy for power electronic transformer (PET, also known as SST) is proposed. The analyzed structure uses two 7-level cascaded H-bridge (CHB) rectifiers. The electrical power is transferred between DClinks of CHB converters using dual-active-bridges (DABs) and low voltage high frequency transformers. The system allows to control the active and reactive power with low level of harmonic ...