Nowadays, ensuring the stability of energy grids is one of the key challenges in modern power engineering, especially in the context of the growing share of renewable energy sources. This instability also affects traction power systems, which are increasingly integrated into the overall infrastructure. Modern traction substations therefore contribute to greater reliability and efficiency of the entire traction grid. At the same time, the control algorithm enables power to be distributed among a larger number of traction substations that cooperate under the same load within a traction section. The power TSSs distribution are based on PQ characteristics, ensuring an allocation that takes into account the nominal power, or overload time of each TSS, mainly in the case of semiconductor topologies. The proposed solution of control algorithm has been evaluated by a mathematical model of cooperating TSS to the traction grid.

This paper presents a mathematical model of AC traction substations (TSS) 25 kV / 50 Hz and their power sharing cooperation using Rail Power Conditioner (RPC) technology. The actual traction grids topologies bring the problem of cooperation of TSS due to differences in their output voltages. Therefore, it is necessary to isolate the traction catenary sections by neutral sections near the switching station between the TSS to prevent a power overflow due to the voltage difference. To enable the sharing of the power of these sections, RPC converters are used, which are placed in the area of the neutral section or directly to the TSS site with a suitable topology. This research deals with an efficient way of controlling this RPC, using proportional resonant controllers, which are widely used in the field of traction grids. This proposed control algorithm has been tested on a developed mathematical model of a traction network with two TSS, where the real conditions in traction grids are included and considered.

This paper describes the advanced AC traction substations topologies using of power electronics components. The traction substations allow the power flow control from the superior power grid to the traction grid. The main part of the paper is to present the output power control of only the sensitive substations, which appropriately distributes the traction load power between the connected substations. The designed control method is tested on a mathematical model of a single-track 25 kV/50 Hz traction grid with three traction substations. The model respects realistic traction site parameters and can be extended to any number of power nodes. The results are analyzed for selected steady and transient states.

The paper is focused on topologies of traction substations for AC railway traction system especially for 25kV, 50Hz (respectively 60Hz). The current progress of power electronic field of study allows to use semiconductor converters as a part of distribution power grid (i.e. for HVDC), for traction issue but also for traction substations. This expansion is related to topologies of TSS, where power electronics are used for symmetrization, compensation, filtration of harmonics of higher order, TSS cooperation, recuperation back to distribution power grid if it is allowed, etc. Conventional transformer topologies used to this day for electrical railway supplies are described in the beginning. The state of the art of TSS, using a power electronic component and the most promising topologies at the same time, is described in the second half of the paper. The main benefit of the paper is comparison of the TSS selected topologies and evaluation of the properties.

High power ultra-fast charging station for public transport systems becomes integral part of an urban power grid. In some cases the station has to be supplied by existing power grid 3×400VAC. This paper describes charging station based on a cost-effective topology with an output power over 300kW intended for charging electrical busses. Main part is focused on control algorithm proposal. Performance is verified by a simulation of steady-state and transient conditions.

This paper describes the sliding discrete Fourier transform algorithm (SDFT) for parallel admittance estimation. The SDFT is a popular algorithm for continual single-point or several-point spectral analyzes of discrete time signals. The main drawback of the SDFT is a numerical stability issue. The paper describes the algorithm of SDFT with guaranteed numerical stability by parallel spectra computation. Furthermore, the paper presents the application of SDFT for continual parameter identification of grid to ground admittance of ac power distribution network. The grid admittance is analyzed by voltage response on injected current into auxiliary winding of the Petersen coil. The spectral analyses of injected current and voltage response are used for Petersen coil tuning. The current is injected by H-bridge voltage source inverter.

Energy storage systems (ESS) have large impact on efficiency and reliability of modern electric traction systems. This paper investigates the fuzzy energy management strategy for ESS based on supercapacitors (SC) for human driven trams. Operating the SC on board of a tram brings the following benefits: reduction of peak power demands, decrease of power consumption, improvement of performance and efficiency. Whereas the commonly used ESS Energy management strategies (EMSs) have been dealing without knowledge of vehicle position, the main interest of the presented research is put on the algorithm using the Global Positioning System (GPS). The tram position, located by a GPS module, is used to predict future energy demands and power flows. This information is used in the preparation of the supercapacitor energy level and its power flow control. The optimal ESS power flow with the respect to the tram position is a very complex problem. For this reason, soft computing techniques are used in this paper. The main part of the proposed ESS EMS is the Takagi-Sugeno Fuzzy controller (T-S Fuzzy). The T-S Fuzzy reduces problem dimensionality using the expert knowledge represented by the rules. The output membership functions were finaly optimized by the Differential Evolution (DE).

This paper deals with topology of indirect frequency converter for new mining machine drive fed directly by 6kV ac power grid. The proposed topology is composed of input cascaded H-bridge active rectifier and output cascaded H-bridge inverter. The main attention is paid to control of input cascade H-bridge active rectifier especially to voltage balancing of the individual power cells (H bridge). The proposed control uses conventional PWM with shifted carriers and voltage balancing is solved separately by control algorithm. The paper describes results of the simulation tests for designed low-voltage laboratory prototype of rated power of 10 kW.

This paper describes novel adaptive multiplicative general parameter finite impulse response filter with real coefficients (MGP-FIR). The MGP-FIR is adaptive, predictive digital FIR filter for fundamental harmonic estimation of distorted signal with small frequency fluctuations without phase shift (time delay). This property is necessary for high quality control of power converters connected to the AC power line (active source rectifiers, voltage inverters, active power filters etc.) The goal of this paper is to present design and simulation results of different MGP-FIR filters and their behavior represented by frequency responses.

This paper describes a control algorithm of a single-phase voltage-source converter with an LCL output filter behaving like a high-quality controlled current source. Designed control algorithm combines model based (feed-forward) control with a feedback direct current control based on resonant controllers. This control method provides precise (low THDi) sinusoidal waveform of required output current. The theoretical conclusions presented in this paper are verified by experiments made on developed laboratory prototype of current source.

This paper describes three implementation alternatives of a multiplicative general parameter finite impulse response filter (MGP-FIR) used as a precise current reference generator for shunt-type active power filters. Compared to the traditional techniques that use fixed digital or analogue filters, the MGP-FIR is an adaptive and predictive algorithm for tracking typical frequency variations and thus avoiding the harmful phase shift of the fundamental sinusoid. This characteristic is essential for maximizing the harmonics reduction ability of the active power filter. The fixed subfilters of the MGP-FIR are pre-optimized by the use of a genetic algorithm. The harmonics reduction ability was verified by extensive simulations. Moreover, a laboratory prototype was developed and experimentally tested under typical non-linear loads. Compared to the previously presented articles on MGP-FIR-based current reference generators, this is the first time when real-valued or fixed-point coefficients are used with the MGP-FIR. In addition, we also improved the originally proposed amplitude detector. The results are compared with those presented earlier.