The paper presents simulation research on a variable structure control scheme of a small variable-speed fixed-pitch wind energy conversion system (WECS) with a three-phase permanent magnet synchronous generator (PMSG) in variable wind conditions. The WECS is connected to a power grid through two back-to-back voltage source converters (VSCs) with a DC link. The presented control algorithm is based on feedforward compensation of the wind turbine aerodynamic torque estimated using a linear disturbance observer (DOB). The torque estimate is employed to determine the effective wind speed, required for setting the reference angular speed, using numerical zero search of a nonlinear function. The simulation model, built in the Matlab/Simulink environment using the Simscape Electrical toolbox, includes the field-oriented control of the PMSG via the machine VSC, performed by cascaded angular velocity and current/torque PI controllers, as well as synchronization with the grid and the reactive power control via the grid VSC. The presented results are focused on the performance of the proposed control in the maximum power point tracking (MPPT) operating region of the WECS for various wind speed profiles.

This article describes problems related to the operation of a virtual micro power plant at the Faculty of Electrical Engineering (FEE), Czestochowa University of Technology (CUT). In the era of dynamic development of renewable energy sources, it is necessary to create alternative electricity management systems for existing power systems, including power transmission and distribution systems. Virtual power plants (VPPs) are such an alternative. So far, there has been no unified standard for a VPP operation. The article presents components that make up the VPP at the FEE and describes their physical and logical structure. The presented solution is a combination of several units operating in the internal power grid of the FEE, i.e., wind turbines, energy storage (ES), photovoltaic panels (PV) and car charging stations. Their operation is coordinated by a common control system. One of the research goals described in the article is to optimize the operation of these components to minimize consumption of the electric energy from the external supply network. An analysis of data from the VPP management system was carried out to create mathematical models for prediction of the consumed power and the power produced by the PVs. These models allowed us to achieve the assumed objective. The article also presents the VPP data processing results in terms of detecting outliers and missing values. In addition to the issues discussed above, the authors also proposed to apply the Prophet model for short-term forecasting of the PV farm electricity production. It is a statistical model that has so far been used for social and business research. The authors implemented it effectively for technical analysis purposes. It was shown that the results of the PV energy production forecasting using the Prophet model are acceptable despite occurrences of missing data in the investigated time series.

This article presents a carrier-based pulse-width modulation (PWM) template for a 5-level, H bridge-based cascaded multilevel inverter (MLI). The developed control concept generates adequate modulation template for this inverter topology wherein a sinusoidal modulating waveform is modified to fit in a single triangular carrier signal range. With this modulation approach, classical multiplicity and synchronization of the triangular carrier signals criterion for the extension of sinusoidal pulse-width modulation, SPWM, to several cascaded 5-level, H-bridge-based MLI topology are removed. The proposed template can be used on the inverter configuration of any level with no further control modification. Nearly even distribution of switching pulses and equalized individual cascaded cell output power were achieved with the proposed modulation scheme. Three 5-level, H-bridge-based MLI units were cascaded for 1-phase, 13-level inverter operation; simulation and experimental results are adequately presented.

The paper deals with analysis of how limited bandwidth of a setup for verification of electrostatic discharge (ESD) generators affects reliability of testing. It is investigated how suppression of a high-frequency part of an ESD pulse spectrum distorts the pulse waveform and affects its standardized time domain metrics: the rise time and the peak value. Restriction of a pulse spectrum is achieved by low-pass filtering with a defined passband. The filtering models high-frequency attenuation of a measurement path, in particular that of an oscilloscope. The analysis is conducted for theoretical ESD pulses, specified by the IEC Standard, as well as for series of real noisy pulses recorded on setups with wideband 6 and 12 GHz oscilloscopes. Discrepancies of rise times and peak currents of filtered pulses with respect to an original input pulse are calculated as measures of distortion due to constraint of a pulse spectrum. It is shown that above 3 GHz, the setup circuit noise is the main factor contributing to measurement uncertainty of the metrics.

This paper investigates how dynamics of an HF oscilloscope affects standardized metrics (i.e., rise time and peak value) of a recorded electrostatic discharge (ESD) current pulse and evaluates the oscilloscope measurement uncertainty. A frequency-domain dynamic model of the oscilloscope, based on measurements of the input reflection and voltage gain magnitude, is derived. The complex voltage gain is approximated with a transfer function to take into account unmeasured phase shift. A high-order discrete-time filter is designed to fit the measured voltage gain magnitude not only in the passband, but also beyond it as well. Since the measured data are burdened with measurement uncertainties, the worst-case deviations of the oscilloscope input impedance and the voltage gain (in the form of envelopes of the frequency responses) are calculated, and components of type B uncertainty of the ESD pulse metrics corresponding to these deviations are estimated using the sensitivity method.

This paper presents research conducted on the development of an innovative system to increase the amount of energy recovered from a high-speed kinetic energy storage based on a three-phase permanent magnet brushless (PM BLDC) motor/generator (mogen) with a flywheel-shaped rotor, compared to the efficiency obtained for standard solutions with power electronics systems. This kinetic energy storage is currently under development. In the system presented in the paper, the regulated DC output voltage of the 6T thyristor bridge is controlled with a tolerance within ±10% of the reference voltage for a variable power load. The input voltage of the rectifier is a three-phase trapezoidal-shaped voltage from the rotating mogen, whose amplitude can vary from 0 to 650 V and frequency from 0 to 250 Hz voltage. The article presents example results of simulation tests of the mogen-based kinetic energy storage model with the thyristors’ firing angle control system. As part of the research, a prototype of the rectifier was built on a laboratory scale, to confirm the validity of the assumptions regarding the synchronization and control method of the bridge using a new design of the thyristor gate drivers.