Voltage source converters (VSCs) are self-commutated converters able to generate AC voltages with or without the support of an AC connecting grid. VSCs allow fast control of active and reactive powers in an independent way. VSCs also have black start capability. Their use in high-voltage direct current (HVDC) systems, comparative to the more mature current source converter (CSC)-based HVDC, offers faster active power flow control. In addition, VSCs provide flexible reactive power control, independent at each converter terminal. It is also useful when connecting DC sources to weak AC grids. Steady-state RMS analysis techniques are commonly used for early-stage analysis, for design purposes and for relaying. Sources interfaced through DC/AC or AC/DC/AC converters, opposite to conventional generators, are not well represented by electromotive forces (E) behind impedance models. A methodology to include voltage source converters (VSCs) in conventional RMS short-circuit analysis techniques is advanced in this work. It represents an iterative procedure inside general calculation techniques and can even be used by those with only basic power electronics knowledge. Results are compared to those of the commercial software package PSS^®CAPE to demonstrate the validity of the proposed rmsVSC algorithm.

For domestic consumers, electricity tariffs usually have two components: one is related to the maximum available current/total power (billed in €/day) and the other concerns to the energy consumption (€/kWh). The main switchboard current is usually limited, according to the contracted power level, by way of automatic switches. To avoid main switchboard tripping by current limit violation, Electric Vehicle (EV) owners may decide to increase their contracted power (and the energy bill) or to adopt charging strategies that limit the global consumption (EV plus house needs) to the contracted current/power. In this paper, an Intelligent Electric Vehicle Charging Controller (IEVCC), allowing to use the contracted power to the maximum extent, is presented. A set of user configurable parameters can be used to define the controller behavior, in order to prevent a full switch-off. Two versions are described: a single user version that can be used at private houses and a mesh version that can be used in multi apartment buildings, providing information about consumed energy, time of use, costs and past bills.

The increasing rating and improved performance of self-commutated semiconductor devices have made possible Voltage-Sourced Converter based High Voltage DC transmission system. VSC-based HVDC power transmission is then becoming a more efficient solution for long distance power transmission, especially for off-shore wind plants. One of the advantages of VSC-based HVDC transmission system is its ability to independently control active and reactive power flow at the AC systems to which it is connected. Both in normal operation or under disturbances in the AC transmission system, the VSC-based HVDC can add additional controllability to the AC system; So that, VSC-based HVDC transmission system can enhance power system stability by modulating their active and reactive power. However, this flexibility is likely to affect the protective relay operation of transmission lines, particularly step distance protective relay. Thus, this paper presents the influence of the different control methods of a VSC-based HVDC transmission system on a distance protective relay.

Steady state security analysis of Electric Power Systems requires identifying, accurately and efficiently, the set of critical contingencies which occurrence can endanger the system's security. Severity indices are used to rank the impact of contingencies in power system security studies. This paper proposes the use of severity indices to study and analyze security problems considering the impacts of Electrical Vehicles (EV) in the Portuguese Electrical Power System. The steady state simulations of the Portuguese Transmission System have been made in PSS/E software from Siemens Power Transmission Distribution, Inc., using snapshots that represent pictures of the real system. Finally, some conclusions that provide a valuable contribution to the understanding of the power system security analysis are pointed out.

Direct and back-flashovers across line insulators are the main cause of transmission line outages, even when shield wires are used. So, the simulation of this phenomenon can be useful to the insulation design as well as to study the effectiveness of corrective actions. The electromagnetic transients program (EMTP) is one of the most important tools in the simulation of electromagnetic transients, with a large library of electric and electro mechanic component models. Also, user defined models can be integrated with the main program. In this work, the integration of user defined models with the EMTP, as well as its application in lightning studies, are shown