The ever increasing progress of high-voltage high-power fully controlled semiconductor technology continues to have a significant impact on the development of advanced power electronic apparatus used to support optimized operations and efficient management of electrical grids, which, in many cases, are fully or partially deregulated networks. Developments advance both the HVDC power transmission and the flexible ac transmission system technologies. In this paper, an overview of the recent advances in the area of voltage-source converter (VSC) HVdc technology is provided. Selected key multilevel converter topologies are presented. Control and modeling methods are discussed. A list of VSC-based HVdc installations worldwide is included. It is confirmed that the continuous development of power electronics presents cost-effective opportunities for the utilities to exploit, and HVdc remains a key technology. In particular, VSC-HVdc can address not only conventional network issues such as bulk power transmission, asynchronous network interconnections, back-to-back ac system linking, and voltage/stability support to mention a few, but also niche markets such as the integration of large-scale renewable energy sources with the grid and most recently large onshore/offshore wind farms.

VSC-Based HVDC Power Transmission Systems: An Overview

Solid-state switch-mode rectification converters have reached a matured level for improving power quality in terms of power-factor correction (PFC), reduced total harmonic distortion at input AC mains and precisely regulated DC output in buck, boost, buck-boost and multilevel modes with unidirectional and bidirectional power flow. This paper deals with a comprehensive review of improved power quality converters (IPQCs) configurations, control approaches, design features, selection of components, other related considerations, and their suitability and selection for specific applications. It is targeted to provide a wide spectrum on the status of IPQC technology to researchers, designers and application engineers working on switched-mode AC-DC converters. A classified list of more than 450 research publications on the state of art of IPQC is also given for a quick reference.

/pdf/a-review-of-single-phase-improved-power-quality-ac-dc-2pm6h4zjxq.pdf

A review of single-phase improved power quality AC-DC converters

The authors discuss high-voltage power conversion. Conventional series connection and three-level voltage source inverter techniques are reviewed and compared. A novel versatile multilevel commutation cell is introduced: it is shown that this topology is safer and more simple to control, and delivers purer output waveforms. The authors show how this technique can be applied to either choppers or voltage-source inverters and generalized to any number of switches.<<ETX>>

Multi-level conversion : high voltage choppers and voltage-source inverters

In this paper, the principle of modularity is used to derive the different multilevel voltage and current source converter topologies. The paper is primarily focused on high-power applications and specifically on high-voltage dc systems. The derived converter cells are treated as building blocks and are contributing to the modularity of the system. By combining the different building blocks, i.e., the converter cells, a variety of voltage and current source modular multilevel converter topologies are derived and thoroughly discussed. Furthermore, by applying the modularity principle at the system level, various types of high-power converters are introduced. The modularity of the multilevel converters is studied in depth, and the challenges as well as the opportunities for high-power applications are illustrated.

Modular Multilevel Converters for HVDC Applications: Review on Converter Cells and Functionalities

New regulations impose more stringent limits on current harmonics injected by power converters that are achieved with pulsewidth-modulated (PWM) rectifiers. In addition, several applications demand the capability of power regeneration to the power supply. This work presents the state of the art in the field of regenerative rectifiers with reduced input harmonics and improved power factor. Regenerative rectifiers are able to deliver energy back from the dc side to the ac power supply. Topologies for single- and three-phase power supplies are considered with their corresponding control strategies. Special attention is given to the application of voltage- and current-source PWM rectifiers in different processes with a power range from a few kilowatts up to several megawatts. This paper shows that PWM regenerative rectifiers are a highly developed and mature technology with a wide industrial acceptance.

http://www.lcda.cl/descargas/rodriguez_dixon_pont_espinoza_lezana05.pdf

PWM regenerative rectifiers: state of the art

Thyristor based multilevel current reinjection (MLCR) current source converter (CSC) provides self-commutation capability to thyristors. It also has high quality line current waveform by accurately shaping the DC bus current using an auxiliary reinjection bridge. However the theoretical and PSCAD/ETDC simulation analysis do not take into account the inevitable stray capacitances and inductances which may influence the thyristor turn-on/off and the simulation switching model may not represent the switching characteristics of the main bridge thyristors fully or accurately. Questions have been raised about the ability to achieve self-commutation with thyristors and the possibility of operating thyristors with negative firing angles. Therefore, it is necessary to experimentally verify whether neglecting the real-world artefacts actually impedes the performance of thyristor based MLCR CSC. The experimental results presented in this paper prove that the auxiliary reinjection circuit can force the thyristor to commutate independently from their respective line-to-line voltages and thyristor converter can operate with a negative firing angle.

/pdf/firing-thyristors-with-negative-firing-angle-using-rd182vgs5g.pdf

Firing thyristors with negative firing angle using multilevel current reinjection concept: an experimental evaluation

The uptake of electric vehicles in New Zealand is rapidly increasing and there is a desire for information about charging systems. This information is required by consumers, engineers, and businesses interested in installing charging infrastructure. This project was completed during the 2015-2016 summer break and aimed to enhance the University of Canterbury EPECentre’s knowledge of charging technologies. In addition to gaining a general understanding of charging technologies, detailed research into rapid DC chargers using the CHAdeMO protocol was conducted. The project also included the building and testing of an open source 12kW rapid DC charger using the CHAdeMO protocol. This paper combines the findings of researching the numerous charging technologies with the practical experience of building the charger. Although the charger was not tested with a compatible car due to time constraints, it was successfully built and initial testing was completed. Plans are also underway to conduct more comprehensive testing on the charger to fully characterise it.

Rapid EV Chargers: Implementation of a Charger

In recent years Operational Transconductance Amplifier (OTA) based integrated circuits, filters and analog circuits have been widely investigated. The usefulness of OTAs over conventional OP-Amps in the design of active circuits are well documented. This paper presents a new sinusoidal frequency-to-voltage converter which can linearly convert low voltage signals which is not possible with commercial converter ICs such as LM2917. This converter is based on an OTA based differentiator and an OTA based half wave rectifier.

Frequency-to-voltage conversion using OTA

In this chapter, the authors discusses the travelling wave transmission line models. The frequency dependent transmission line model was presented. Details of transmission line geometry and conductor data are required in order to calculate accurately the frequency-dependent electrical parameters of the line. The simulation time step was based on the shortest response time of the line. The chapter also presents the phase-domain models which is the most accurate and robust for detailed transmission line representation. Calculation of electrical parameters for overhead power transmission lines and underground power cables were also demonstrated.

Transmission lines and cables

In recent years Operational Transconductance Amplifier based high frequency integrated circuits, filters and systems have been widely investigated. The usefulness of OTAs over conventional OP-Amps in the design of both first order and second order active filters are well documented. This paper discusses some of the tunability issues using the Matlab/Simulink® software which are previously unreported for any commercial OTA. Using the simulation results two first order voltage controlled all pass filters with phase tuning capability are proposed. Keywords—All pass filter, Operational Transconductance Amplifier, Simulation.

Neville R. Watson

Papers

Firing thyristors with negative firing angle using multilevel current reinjection concept: an experimental evaluation

Rapid EV Chargers: Implementation of a Charger

Frequency-to-voltage conversion using OTA

Transmission lines and cables

Simulation of Voltage Controlled Tunable All Pass Filter Using LM13700 OTA