Nowadays, high voltage direct current (HVDC) transmissions are gaining relevance in long distance and renewable energy integration projects over the conventional alternating (AC) due to several advantages as improved flexibility independent active reactive power controllability. Despite that, currents collapses generated by fault conditions HVDC systems imply some unresolved technical challenges regarding detection, location clearance of faults. Faults have be cleared a very short time range...

Given the current evolution of Voltage Source Converters (VSC), Multi-Terminal High Direct Current (MTDC) grids are now becoming a real possibility. Still, some technical issues have to be addressed. The protection (HVDC) is main challenge that slowing down development MTDC grids. Hence, this paper focuses on systems. Thus, devices, fault-clearing strategies and system requirements considered. topic review different types methods for systems shown in literature. They can classified depending...

Traditionally, the detection of high-resistance earth faults has been a difficult task in compensated medium-voltage (MV) distribution networks, mainly due to its very low-current fault. To date, several techniques have proposed detect them: using current injection neutral, superposing voltage signals, varying value arc suppression coil, etc. These use different parameters, such as fault resistance earth, line asymmetries, or partial residual neutral voltages. In this paper, phase asymmetry...

This paper presents a new method of detecting low-current faults in high impedance grounded distribution networks, both compensated and ungrounded medium voltage networks. Based on monitoring the residual variations line phase asymmetries, proposed algorithm can be used combination with other steady-state data-based methodologies, order to detect existence single-phase ground fault, as well identify faulty feeder phase. Although it could also networks by means techniques (such injection...

Reconductoring with high-temperature low-sag (HTLS) conductors is an alternative to the traditional uprating methods. An increase in obtained rating depends on mechanical and thermal behaviours of conductor. The HTLS are presented calculation methods analysed taking into account special characteristics these conductors. widely used graphical method recently developed STOC have been analysed.

Considering the relevance that HVDC systems are expected to have in future of power networks, this paper aims provide a wide overview protection against DC faults. In particular, detection and location techniques been proposed date analyzed, focusing on approaches set be applied modern which comprise VSC-HVDC MTDC systems. Although these present series remarkable advantages compared traditional LCC-HVDC systems, they require fast tripping fault, is an important challenge design system.

This paper describes the line rating forecasting techniques based on NWP models. Taking wind power as a base for overhead forecasting, identifies differences between and forecasting. Recent experiences about are also described. As result, requirements defined. Finally, pilot project of is presented results discussed.

The performance of protection relays depends on many factors and needs to be carefully evaluated. One the significant impacting system behaviour is power quality. Depending which quality parameters distorted, influence digital will different. This paper analyses deterioration relays. In first part paper, historical limitations related electromechanical signal processing algorithms used in are outlined. second part, distorted waveforms analyzed. Two aspects taken into account: harmonics...

The overhead line rating methods have a double requirement: accuracy and security. A method is accurate if the forecasted close to actual rating. It secure lower or equal This paper compares several in terms of security based on results pilot project. Indicators for conductor temperature exceedance underestimation are used compare methods. static rating, ambient-adjusted weather forecasts analyzed.

The present paper presents an analytical model for the evaluation of short-term frequency response in isolated power grids with increasing penetration renewable energy sources. analysis includes synthetic inertia and primary control schemes proposed literature wind plants. Thus, future insular scenarios can be estimated. is verified a real-case study: Terceira island Açores, small size European high potential

Ferroresonance can severely affect voltage transformers, causing quality and security problems. The possibility of appearing a ferroresonance phenomenon is mainly based on an existing series connected capacitance nonlinear inductance. However, factors that may influence it are not only limited to these considerations, but also several constructive, design, operation protective parameters. This paper analyses the process obtaining ferroresonant behaviour medium (MV) phase-to-phase transformer...