M. Moranchel

Distributed Approach for SmartGrids Reconfiguration Based on the OSPF Routing Protocol

Smart grids (SG) are essential for efficient management and monitoring of electric power networks. One of the most important tasks in SG focuses on fault detection and automatic network reconfiguration. This process allows minimizing power losses and load balancing in distribution networks. In this paper, an adaptation of the open shortest path first (OSPF) routing protocol to accomplish the network reconfiguration task is proposed. The algorithm is intended to run in secondary substation nodes over an agent-based distributed architecture. The proposed algorithm has been tested on the IEEE 123 modified node test feeder and on an actual grid deployed by an electrical distribution company. Moreover, a performance comparison with a typical centralized reconfiguration algorithm is carried out.

Circulating current elimination in Modular Multilevel Converter with resonant controllers

Modular Multilevel Converters (MMCs) are attracting considerable interest for high-power and medium voltage applications due to several advantages, such as reduced THD grid current, high voltage blocking, etc. However, one of the major drawbacks of this topology is the existence of the circulating current which increases the power losses and reduce the efficiency of the converter. In this paper one approach to reduce the circulating current is shown. The approach is based on resonant controllers. The resonant controller is analyzed and tuned in order to reduce the circulating current. Moreover, the controller has been tested and validated in a real processing platform designed to control large multilevel converters and in a real MMC prototype.

Implementation of nearest level modulation for Modular Multilevel Converter

Nowadays there are several modulation techniques to control multilevel power converters. In this paper its shown an implementation of the nearest level modulation for a six-level modular multilevel converter. The use of this modulation is a very interesting option when the number of submodules is large because of the complex of this modulation is independent of the number of levels. The implementation of the modulation has been made in a real hardware platform designed to control large multilevel converters. Moreover, the modulation has been tested in a high power six-level prototype of Modular Multilevel Converter.

Six-level modular multilevel converter prototype with centralized hardware platform controller

This paper presents a 25kW six-level Modular Multilevel Converter prototype. The designed prototype is an industrial power converter that can be used by the industry. The converter is shown together with a high-performance hardware platform control designed for large multilevel converters. The hardware platform is a custom platform based on Zynq-7000 System-On-Chip that provides high processing performance together with high-speed communications.

Tuning of resonant controllers applied to the current control of Voltage-Source Converters

The current control of a Voltage-Source Converter (VSC) requires continuous innovation due to the increasing demands on the permissible level of harmonics in the mains. Nowadays, one of the most used techniques is the resonant control, which can be implemented in various ways, all having in common that they have a theoretical infinite gain at the resonant frequency. Four of those ways are discussed in this paper, comparing their results when applying them to the current control of a VSC. Two of them were originally used to implement the voltage control of a converter and they have now been applied to the current control of a grid-connected power converter. Simulation and experimental results are provided in order to compare their performance in a grid whose harmonic content includes harmonic sixth, analyzing typical control parameters such as settling time, maximum overshoot and steady-state error.

Selective Harmonic Elimination modulation for Medium Voltage Modular Multilevel Converter

The use of medium voltage converter in applications of voltage and grid supporting is increasing. To improve the power quality from the point of view of total harmonic distortion, this paper proposes the use of a Modular Multilevel Converter (MMC) with Selective Harmonic Pulse-Width Modulation (SHE-PWM). SHE-PWM allows control the harmonics generated at the output while it provides reduced switching losses. The main drawback of this modulation technique is to solve the equation system required to obtain the switching angles that minimize the generated harmonics. This paper studies the SHE-PWM for a six-level MMC where fifteen harmonics are minimized. The switching angles required to minimize the harmonics are obtained using Genetic Algorithms. Simulation and experimental results are presented to verify the proposed scheme for the MMC.

Analysis of medium voltage modular multilevel converters for FACTS applications

This paper shows a comparison between two modular multilevel topologies that are very used nowadays in medium voltage applications such as FACTS. These two used topologies are on one hand the modular multilevel converter, which traditionally has been proposed for high voltage offshore connections; and on the other hand the cascaded H-bridge converter that has been used mainly in motor drives. Both topologies show a good behavior in those applications, but this paper aims to prove that these topologies can be used in FACTS applications, mainly STATCOM systems, with a very interesting results.

Circulating current elimination in Modular Multilevel Converter with repetitive controllers

One of the most up-and-coming multilevel converters are the Modular Multilevel Converters (MMCs) due to its simple structure which can be adapted to wide range of voltage levels. Nevertheless, one the main disadvantages of MMC is the presence of the circulating current which reduces the efficiency. With a view to overcome this problem, this paper proposes an approach to control and reduce the circulating current based on repetitive controllers. The repetitive controller is described and adapted to minimize the circulating current. In addition, experimental results in a MMC prototype have been carried out to validate the controller.

Comparative of modulation techniques for modular multilevel converter

The modulation technique chosen for use in the power converter largely defines the harmonics generated, consequently it is a fundamental part that must be studied. In this paper its shown a comparative between different modulations techniques applied to a modular multilevel converter. Sinusoidal Pulse Width Modulation, Space-Vector Modulation and Nearest Level Modulation are studied. The whole techniques are explained and finally are implemented in a hardware platform and tested in a real high-power six-level modular multilevel converter.

Fault-tolerant cascaded H-bridge converter for an induction motor drive

In this paper an induction motor drive system based on a fault-tolerant cascaded H-bridge converter is presented. The proposed system is composed by an induction motor fed through a 13-level cascaded H-bridge converter. In this case a neutral shift method has been implemented for the CHB converter in order to make it fault-tolerant. The proposed system has been modelled and tested in Matlab-Simulink.