Multilevel Converters: An Enabling Technology for High-Power Applications

| Multilevel converters are considered today as the state-of-the-art power-conversion systems for high-power and power-quality demanding applications. This paper presents a tutorial on this technology, covering the operating principle and the different power circuit topologies, modulation methods, technical issues and industry applications. Special attention is given to established technology already found in industry with more in-depth and self-contained information, while recent advances and state-of-the-art contributions are addressed with useful references. This paper serves as an introduction to the subject for the not-familiarized reader, as well as an update or reference for academics and practicing engineers working in the field of industrial and power electronics.Ministerio de Ciencia y Tecnología DPI2001-3089Ministerio de Eduación y Ciencia d TEC2006-0386

Implementing UPQC based Intelligent Islanding for the Microgrid System

Increased penetration of small scale renewable energy sources in the electrical distribution network, improvement of power quality has become more critical than where the current harmonics or disturbances and level of voltage can vary widely. For this reason, Custom Power Devices (CPDs) such as the Unified Power Quality Conditioner (UPQC) can be the most appropriate solution used for improving the dynamic performance of the distribution network, where accurate prior knowledge may not be available. Therefore, the main objectives are (i) placement (ii) integration (iii) capacity enhancement and (iv) real time control of the Unified Power Quality Conditioner (UPQC) to improve the power quality of a distributed generation (DG) network connected to the grid or microgrid. A new integration method of the UPQC has been developed: helps to the DGs to deliver quality of power in the case of islanding and help to reintegrate with the grid seamlessly post fault. It perform both control operation such as Detection of Islanding and reconnection techniques, hence, it is termed UPQC?G. The DG Inverter with storage supplies the active fundamental power only and the shunt part of the UPQC compensates the reactive and harmonic power of the load during both interconnected and islanding mode

Improving long line stability by integrating renewables using static synchronous generators

Postprint (author's final draft

A Robust Consensus Algorithm for Current Sharing and Voltage Regulation in DC Microgrids

In this paper a novel distributed control algorithm for current sharing and voltage regulation in Direct Current (DC) microgrids is proposed. The DC microgrid is composed of several Distributed Generation units (DGUs), including Buck converters and current loads. The considered model permits an arbitrary network topology and is affected by unknown load demand and modelling uncertainties. The proposed control strategy exploits a communication network to achieve proportional current sharing using a consensus-like algorithm. Voltage regulation is achieved by constraining the system to a suitable manifold. Two robust control strategies of Sliding Mode (SM) type are developed to reach the desired manifold in a finite time. The proposed control scheme is formally analyzed, proving the achievement of proportional current sharing, while guaranteeing that the weighted average voltage of the microgrid is identical to the weighted average of the voltage references.Comment: 12 page