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Abstract. The paper presents different solutions applicable in power converter systems for connecting power grids with energy storage systems such as superconducting magnetic energy storage (SMES), supercapacitor energy storage (SES) or chemical batteries. Those systems are characterized by bidirectional current flow between energy storage and power grid. Two-level converters (AC-DC and DC-AC converters) dedicated for low power energy storage compatible with 3£400 V-type power grids are proposed. High power systems are connected with 3£6 kV-type power grids via transformers that adjust voltage to the particular energy storage or directly, based on multilevel power converters (AC-DC and DC-AC) or dual active bridge (DAB) systems. Solutions ensuring power grid compatibility with several energy storage systems of the same electrical parameters as well as of different voltage-current characteristics are also proposed. Selected simulation results illustrating operation of two system topologies of 200 kW power for two-level converter and neutral point clamped (NPC) three-level converter are presented.Key words: power converter, superconducting magnetic energy storage (SMES), supercapacitor energy storage (SES), distribution system. Selected converter topologies for interfacing energy storages with power gridA. DOMINO, K. ZYMMER * , and M. PARCHOMIUK Electrotechnical Institute, 28 Pożaryskiego St., 04-703 Warsaw, Poland bility of limiting the temporary increases in power drawn from the grid during start-up of high-power equipment and operation under overload. Note that the hybrid group of energy storage systems with different current-time characteristics, described in this paper, can assure simultaneous compensation of the peak power and long overload state. The peak power is an essential parameter of the electricity tariff in industrial plants. The systems coupling power grid with energy storage can be divided into two groups:• voltage systems referred to the energy storages as supercapacitors (SES) and battery trays [17,[20][21][22][23][24][25][26][27]], • current systems for SMES energy storage type [28][29][30][31][32][33][34], In those solutions an active rectifier is connected to the grid [28], which results from the requirement of bi-directional energy flow of an energy storage, operating directly with bi-directional DC-DC converter [14]. This solution provides both powering and returning energy to the grid with unity power factor. The paper discusses selected topologies of converter systems connecting the energy storage and power grid with different rating parameters using transformers and transformer-less solutions. Converter topologies for interfacing energystorages with grid 2.1. Topology 1. The basic scheme of the arrangement is shown in Fig. 1, where superconducting choke is used as the energy storage element -SMES. The system consists of an AC-DC converter connected to the power grid and the bi-directional DC-DC converter in the form of the pulse current regulator [13]. It is also possible to use battery ...

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