Elena Makovenko

Passive power decoupling approach for three-level single-phase impedance Source Inverter based on resonant and PID controllers

Single-phase inverter suffers from double-frequency power ripples in the input side transferred there from the ac-side. To mitigate this ripple, two types of power decoupling approaches can be applied: passive power decoupling and active power decoupling. We present a technique of passive power decoupling realized by modifying the control strategy. The main idea is to produce the time-varying shoot-through duty cycle to charge and discharge impedance capacitors when needed in the desired sequence for mitigating input power ripple without deteriorating the output power quality. The main contribution of the paper is in the determination of the parameters of a regulator taking into account the dynamic feature of the quasi-Z-source network. The validity of the proposed control strategy was confirmed by simulation results in PSCAD. The results show that this strategy can be applied for practical applications.

Single-phase 3L PR controlled qZS inverter connected to the distorted grid

This paper presents a single-phase three-level NPC qZS inverter connected to a distorted grid using PID and PR regulators. A case study system along with the control strategy are described. Tuning approaches for PID and PR regulators are addressed and validated by means of simulation results. The stability domain and limitations of the regulator parameters are also discussed.

qZS Inverter as Synchronverter in Small-Scale Micro-Grid

Focus is on the case study of a synchronveter model use in the qZS inverter working in an islanding operation mode. Main tasks and control principles of a sychronverter in the microgrid are explained. Theoretical assumptions are tested and verified with Psim simulation model with different types and powers of microinverter loads. General waveforms are presented and discussed. Also, the effectiveness of synchronverter implementation is verified by means of grid regulation capability. Additionally, we address the most challenging tasks for further developments and improvements of the qZS inverter based synchronverter in microgrids. DOI: http://dx.doi.org/10.5755/j01.eie.24.2.20636

Modified DQ control approach for three-phase inverter

This paper proposes modified dq control strategy that improves the dynamic response of the grid-connected inverter compared to the conventional approach. The idea is described and validated by means of simulation results. The transient time in traditional approach is 10 times slower than in the modified inverter with the same regulator parameters. The THD of the output current is almost the same.

Three-level single-phase quasi-Z source inverter with active power decoupling circuit

Single-phase inverters suffer from double-frequency ripple of the input power. For mitigation, an input capacitor is applied but the fluctuation range of power across it is limited according the desired fluctuation in the dc-link voltage. To realize power decoupling without changes in the main circuit and in the control strategy of it, an additional independent power decoupling circuit can be applied, where the buffer capacitor works mainly as a storage element that operates with a part of the ripple of the input power. This paper proposes a three-level neutral-point-clamped impedance source based converter with active decoupling circuit connected to the internal capacitors. Our simulation results validate the proposed solution. Its advantages are very simple control strategy and the possibility of storage battery connection.

Review of Novel Topologies for PV Applications

Renewable energy capacity has been growing rapidly, exceeding 140 GW of installed power in solar Photovoltaic (PV) power generation. Along with PV installations, the variety of applied power electronics topologies has also increased, resulting in a key point of future Smart Grids, as long as they allow new operation possibilities. This paper reviews the emerging topologies for PV applications that could be used in the generation of new smart inverters. A particular focus is on impedance-source converters and naturally clamped solutions. Pros and cons along with areas of application are summarized.

Control scheme of a Three-Phase Three-Level NPC qZ-Source inverter with LCL filter for RES applications

This paper presents the design for the control scheme of a three-level three-phase neutral-point-clamped quasi-Z-Source inverter which employs an LCL filter for the connection to the grid. A state-feedback based control is developed so as to attain a fully decoupled control of the active and reactive power exchanged with the grid. In addition, a PI regulator is tailored in order to control the dc-link voltage of the inverter. The complete control strategy, along with the inherent capabilities of the quasi- Z-Source inverters, signifies that this kind of power converters is suitable for renewable energy source applications.

A three-phase zero-current-transition and quasi-zero-voltage-transition inverter/rectifier with reduced stresses on devices and components

This paper proposes a new soft-switching strategy for three-phase inverter and rectifier applications. All the main switches and auxiliary switches are turned on and turned off under zero-current-transition (ZCT) conditions. Compared to existing ZCT techniques, the diode reverse recovery is reduced. In addition, the current stresses the auxiliary switches is reduced and evenly distributed. The operational principle and design aspects are described. Results of modeling of this scheme working in a mode of the rectifier are presented.