Introduction Energy Factor (EF) and Sub-Sequential Parameters Basic Mathematics of Digital Control Systems Mathematical Modeling of Digital Power Electronisc Digitally Controlled AC/DC Rectifiers Digitally Controlled DC/AC Inverters Digitally Controlled DC/DC Converters Digitally Controlled AC/AC Converters Open-Loop Control for Digital Power Electronics Closed-Loop Control for Digital Power Electronisc Energy Factor Application in AC and DC Motor Drives Applications in Other Branches of Power Electronics

Digital Power Electronics and Applications

The problem associated with economic dispatch of battery energy storage systems (BESSs) in alternating current (AC) distribution networks is addressed in this paper through convex optimization. The exact nonlinear programming model that represents the economic dispatch problem is transformed into a second-order cone programming (SOCP) model, thereby guaranteeing the global optimal solution-finding due to the conic (i.e., convex) structure of the solution space. The proposed economic dispatch model of the BESS considers the possibility of injecting/absorbing active and reactive power, in turn, enabling the dynamical apparent power compensation in the distribution network. A basic control design based on passivity-based control theory is introduced in order to show the possibility of independently controlling both powers (i.e., active and reactive). The computational validation of the proposed SOCP model in a medium-voltage test feeder composed of 33 nodes demonstrates the efficiency of convex optimization for solving nonlinear programming models via conic approximations. All numerical validations have been carried out in the general algebraic modeling system.

https://www.mdpi.com/2079-9292/9/10/1677/pdf

A second-order cone programming reformulation of the economic dispatch problem of bess for apparent power compensation in ac distribution networks

Analysis of the efficiency and structure of energy consumption in the industrial sector in the European Union countries between 1995 and 2019

Analysis of the level of energy security in the three seas initiative countries

This paper presents a passivity-based control (PBC) design methodology for three-phase voltage source inverters (VSI) for uninterruptable power supply (UPS) systems where reduced harmonic distortions for the nonlinear load, reduced output voltage overshoot, and a restricted settling time are required. The output filter design and modification for efficient control and existing challenges with the assignment of scaling coefficients of the output voltage, load, and inductor currents are addressed and analyzed. Notably, special attention is given to the modulator saturation issue through implementing an accurate converter model. Applications of the two versions of PBC in three-phase voltage source inverters using stationary αβ and rotating dq frames for a constant frequency of the output voltage are presented. Furthermore, the influence of the PBC parameters on the power converter performance is investigated. A comparative simulation and the experimental results validate the effectiveness of the presented passivity-based control design methodology.

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Passivity-Based Control Design Methodology for UPS Systems

A comparative evaluation of the different, very popular powder magnetic materials for a voltage source inverter output filter coil core is presented. The basic continuous model of the inverter is simply based on the output filter transfer function. This model is used in the majority of inverter control designs. That is why the change of inductance and the increase of the equivalent serial resistance that is caused by power losses in the core and any other parasitic parameters of the coil should be known in the operating point because they depend on the frequency and the amplitude of the magnetising current. The theoretical calculation of these parameters variability is very inaccurate because of the complex voltage waveform on the coil, so the direct measurements of the inverter control transfer function are presented in aim to enable the choice of the most useful magnetic material for the inverter design.

Selecting the coil core powder material for the output filter of a voltage source inverter

The power losses in a voltage source inverter (VSI) are the sum of the additional constant power losses of the local power supply, the inverter circuits as well as the main power conversion losses. Power conversion losses consist of the power losses on switches (e.g. static power losses on the resistances of the switches in the “on state” and the dynamic switching power losses), the power losses on the serial resistances of the filter inductor winding together with the resistances of all of the serial inverter connections and the power losses of the filter coil, which are dependent on the material of the filter coil core. All of these power conversion losses can be presented as losses on the one equivalent serial resistance that is connected serially with the filter coil. This nonlinear (depending on the load and the switching frequency) serial equivalent resistance Rse can be calculated from the parameters of the maximum point of the measured magnitude Bode plot of the control transfer function of the inverter. The paper presents the concept of measuring the Bode plots of the control transfer function in order to get the serial equivalent resistance and to calculate the power conversion losses of an experimental model and discusses the accuracy of the results.

Measuring the power conversion losses in voltage source inverters

This paper proposes a method to reduce the output voltage distortions in voltage source inverters (VSI) working with impedance networks. The three main reasons for the voltage distortions include a discontinuous current in the coils of the impedance network, the double output frequency harmonics in the VSI’s voltage output caused by insufficient capacitance in the impedance network, and voltage drops on the bridge switches during the shoot-through time. The first of these distortions can be reduced by increasing the current of the impedance network when the output VSI current is low. This method requires storing energy in the battery connected to the DC link of the VSI during the “non-shoot through” time. Furthermore, this solution can also be used when the Z-source inverter works with a photovoltaic cell to help it attain a maximum power point. The Z-source inverter is essentially a voltage source inverter with the Z-source in the input. In this paper, the theory behind basic impedance networks of Z-source and quasi-Z-source (qZ-source) is investigated where simulations of the presented solutions and experimental verification of the results are also presented.

Łukasz Dyga

Papers

Passivity-Based Control Design Methodology for UPS Systems

Selecting the coil core powder material for the output filter of a voltage source inverter

Measuring the power conversion losses in voltage source inverters

Controlled Energy Flow in Z-Source Inverters

Sterowanie "Passivity Based Control" w trójfazowych falownikach napięcia przeznaczonych dla systemów UPS