Abstract
The operation of remote and isolated or islanded power systems is often very challenging because of their small system inertia. Moreover, economic and environmental pressure has led to an increasing renewable power penetration, particularly in wind generation and solar photovoltaics (PV). Simultaneously, significant technological progress has been made in terms of control capability of grid assets [generators, controllable loads such as electric vehicles (EVs), and energy storage systems], mostly exploiting the capabilities of power ?electronics. In this context, several advanced control solutions can be implemented, supporting and improving the robustness of the operation in terms of fast frequency and voltage control responses. In this article, the Portuguese islands are taken as a case study. Within the Madeira archipelago (Porto Santo and Madeira islands), two approaches were envisioned. For Porto Santo Island, the main goal is the sizing of a flywheel energy storage system (FESS) to avoid frequency stability problems. For Madeira Island, the objective relies on the exploitation of hydro resources through the quantification of the technical benefits resulting from variable speed hydro pumping stations that are able to provide primary frequency regulation services in the pump operation mode. In addition, this article also addresses the benefits of introducing EVs in Flores Island in the Azores Archipelago. Finally, to support the development of innovative technological solutions for this type of power system, a laboratory setup based on scaled test systems was also set up and is described. A set of applications was specifically developed for such autonomous power systems. The laboratorial infrastructure allowed the testing of ?solutions and prototypes for hardware and software modules related to those applications. © 2013 IEEE.

Abstract

Abstract
This paper presents the approach followed under project SENSIBLE to prove, in field-test scenarios, the benefits of integrating and coordinating small-scale storage devices to: (i) reduce the impact of Distributed Renewable Energy Sources in the Low Voltage grid and (ii) support the transition and the operation in islanding mode in the demonstration grid. The functional and ICT architecture developed for the Portuguese Demonstrator of Évora is presented, focusing in the use cases defined to test and validate the tools developed to enable the active management of the LV grid during both normal and islanded modes.

Abstract
The reduction or elimination of incentives for the installation of decentralized generation directly at the customers' premises, favoring self-consumption, can bring significant changes for distribution network operation. According to the new Portuguese law, injection of energy into the distribution grid is discouraged since prosumers receive only 90% of the energy cost in the Iberian Energy Market. In order to lower energy bills, the possibility of storing excess energy is being considered as a possible solution. In this paper, an optimization framework is proposed to model the operation of consumers with renewable-based Distributed Generation (DG) and storage capacity and assess their aggregated effect at the level of the MV grid using a multi-temporal Optimal Power Flow (OPF). The proposed algorithm is then tested in a real Portuguese MV network to evaluate its performance. Finally, a financial viability analysis is performed considering the installation of small PV generators and storage devices at the residential level.

Abstract
One of the main constraints for Renewable Energy Sources (RES) integration in LV networks are overvoltages caused by changing the normal power flow of the network. In favourable weather conditions high voltages may lead to overvoltage trips thus preventing the injection of renewable energy into the grid. An optimized management of power injection from controlled RES to keep the grid voltage within regulatory limits enables a larger energy output and deployment of distributed generation. The SuSTAINABLE project developed a centralized algorithm based on a hierarchical methodology to control distributed power injection and solve the identified issue. A decentralized algorithm based on a coordinated droop control embedded in the inverters was developed as well. In order to evaluate the proposed algorithms a controllable PV µG and batteries were installed at the end of the feeder of a real LV network operated by EDP Distribuicao. The obtained results are presented in this paper and show that a hierarchical methodology to control power injection could optimize RES energy production while maintaining voltages within bounds, thus enabling a larger deployment of RES at the LV levels.

Abstract
This paper presents a study about the influence of Distributed Energy Resources' (DER) flexibility on the operation of a Medium Voltage (MV) network, in a Smart Grid (SG) environment. An AC multi-temporal Optimal Power Flow (OPF) tool was developed and used to simulate the impact of the DER flexibility (including storage devices, EVs, controllable loads and micro-generation) in distribution network operation. Some simulations are presented, demonstrating the impact that DER flexibility can have on solving operation problems namely in terms of branch loading and voltage limits.