This paper presents a new method to enhance the participation of variable-speed wind energy conversion systems (WECS) in existing frequency regulation mechanisms. The proposed approach, based on a modified inertial control scheme, takes advantage of the fast response capability associated with electronically-controlled WECS, allowing the kinetic energy stored by rotational masses to be partly and transiently released in order to provide earlier frequency support. An additional improvement is achieved by communicating the WECS response to conventional generators so that these can eventually take care of the full load imbalance. Several simulations using a two-area test system are performed to demonstrate the benefits of the proposed scheme.

This study addresses the benefits of incorporating flexible DC links into radial distribution networks, which are subject to continuous load growth and higher levels of distributed generation penetration. To compare the use of DC links with conventional network reinforcement measures, an optimisation framework is developed. The main feature of the proposed formulation is that, irrespective of the criterion chosen to quantify the benefits of adding DC links, the same objective function is handled. Maximising or minimising a single-objective function, subject to the same set of constraints, allows different planning criteria to be assessed. The proposed optimisation framework is applied to actual networks embedding distributed generation. Two- and three-terminal voltage source converter-based DC links are considered in order to numerically illustrate the potential benefits of this technology in distribution systems.

This study presents and thoroughly compares different alternatives to create DC links in distribution networks by means of voltage source converters (VSC). Such links give rise to fully controllable loops in nowadays radially operated systems, allowing higher levels of distributed generation penetration. Suitable VSC-based devices are reviewed and compared from several points of view, including topologies, degrees of freedom, operating ranges and performance. Several case studies, involving actual urban and rural distribution networks, are worked out to show the potential benefits provided by the use of the proposed smart links.

This paper focuses on improving the solution techniques for the AC SCOPF problem of active power dispatch by using the DC SCOPF approximation within the SCOPF algorithm. Our approach brings two benefits compared with benchmark SCOPF algorithms: it speeds up the solution of an iterative AC SCOPF algorithm thanks to a more efficient identification of binding contingencies and allows improving the objective by an appropriate choice of a limited number of corrective actions for each contingency. The proposed approach is illustrated on five test systems of 60, 118, 300, 1203, and 2746 buses.

The smart-grid era is characterized by a progressive penetration of distributed energy resources into the power systems. To ensure the safe operation of the system, it is necessary to evaluate the interactions that those devices and their associated control algorithms have between themselves and the pre-existing network. In this regard, Hardware-in-the-Loop (HIL) testing approaches are a necessary step before integrating new devices into the actual network. However, HIL is a device-oriented testing approach with some limitations, particularly considering the possible impact that the device under test may have in the power system. This paper proposes the Power System Hardware-in-the-Loop (PSHIL) concept, which widens the focus from a device- to a system-oriented testing approach. Under this perspective, it is possible to evaluate holistically the impact of a given technology over the power system, considering all of its power and control components. This paper describes in detail the PSHIL architecture and its main hardware and software components. Three application examples, using the infrastructure available in the electrical engineering laboratory of the University of Sevilla, are included, remarking the new possibilities and benefits of using PSHIL with respect to previous approaches.