Abstract
As Distributed Generation (DG) is increasingly integrated into the networks, intermittency issues of some types of DG (such as wind energy) will potentially increase network operating costs or decrease network security. Concern regarding these effects has grown among Network Operators and in order to avoid them, new or updated wind parks are required to provide ancillary services to the network. These ancillary services include the fault ride-through capability and mainly those wind parks connected to a collector switching or distribution substation are asked to provide this service. Although some wind parks can already supply fault ridethrough capability to the network, most of them are still largely unable to do so due to the current DG protection scheme. This work concentrates on the development and assessment of new settings for the wind park protection scheme by closed-loop test in real time. This aims to allow wind parks to provide fault ride-through capability to the distribution network. A distribution network with a DFIG based wind turbine with ride-through-fault capability was modelled on the RTDS Simulator. The protective relay settings were then implemented into a commercial numerical programmable relay to be assessed by closed-loop real time test. Conclusions of the protective relay with the fault ridethrough requirement are presented and discussed.

Abstract
Using power-hardware-in-the-loop is a solution for testing the behavior of devices on an emulated grid, with greater flexibility and avoiding the introduction of disturbances or critical operating conditions in the utility grid. This paper highlights the implementation of such a setup, its challenges and the solutions to cope with its limitations. The emulated grid is then used for the experimental validation of a 10kVA converter, regarding fault-ride-through, dynamic reactive current support and frequency and voltage based droop control, leading to the identification of design improvement recommendations.

Abstract

Abstract
This paper proposes a near to real-time local market to provide reactive power to the transmission system operator (TSO), using the resources connected to a distribution grid managed by a distribution system operator (DSO). The TSO publishes a requested reactive power profile at the TSO-DSO interface for each time-interval of the next delivery period, so that market agents (managing resources of the distribution grid) can prepare and send their bids accordingly. DSO resources are the first to be mobilized, and the remaining residual reactive power is supplied by the reactive power flexibility offered in the local reactive market. Complex bids (with non-curtailability conditions) are supported to provide flexible ways of bidding fewer flexible assets (such as capacitor banks). An alternating current (AC) optimal power flow (OPF) is used to clear the bids by maximizing the social welfare to supply the TSO required reactive power profile, subject to the DSO grid constraints. A rolling window mechanism allows a continuous dispatching of reactive power, and the possibility of adapting assigned schedules to real time constraints. A simplified TSO-DSO cost assignment of the flexible reactive power used is proposed to share for settlement purposes.

Abstract
This paper presents a methodology to estimate flexibility existing on TSO-DSO borderline, for the cases where multiple TSO-DSO connections exist (meshed grids). To do so, the work conducted exploits previous developments regarding flexibility representation through the adoption of active and reactive power flexibility maps and extends the concept for the cases where multiple TSO-DSO connection exists, using data-driven approach to determine the equivalent impedance between TSO nodes, preserving the anonymity regarding sensitive grid information, such as the topology. This paper also provides numerical validation followed by real-world demonstration of the methodology proposed.

Abstract
The growing concern about global climate change has led the European Union and the Portuguese Government to set targets for the percentage of electricity to be produced from renewable sources. In order to achieve the defined targets, Distributed Generation (DG) is expected to be increasingly integrated into networks. However, the intermittency of some of those DGs (such as wind energy) may enhance network operating costs or decrease network security. Thus, Network Operators started to concern about these effects and in order to avoid them, new wind parks were required to provide ancillary services to the network. These ancillary services include the ride-through-fault capability. Although some wind parks can already supply ride-through-fault capability to the distribution network (i.e. wind parks with Double Fed Induction Generators (DFIG)), most of them are still largely unable to do so due to the current DG protection scheme. This work concentrates on the development of new settings for the DG protection scheme which aims at allowing DG to provide ride-through fault capability to the distribution network. A DFIG with ride-through-fault capability was modeled on PSCAD/EMTDC and tested under the Portuguese Distributed Generation Protection Scheme Regulation Code. New relay settings for the DG protection scheme are advanced and simulated on PSCAD/EMTDC software in order to permit DGs providing ride-through fault capability to the distribution network. Conclusions of the new relay settings performance are withdrawn and commented on.