Estefanía Planas

A Note on the Normalization of Spanish Electricity Spot Prices

Merit order of renewable generation has produced an increasing, relevant number of zero values in Spanish electricity spot prices since 2010, in contrast with the rest of markets which rarely present zero values. This letter shows that existing methodologies for normalizing the price distribution fail to yield a proper normalization. This letter proposes a new algorithm based on Nataf transformation which addresses this issue and ensures a correct normalization. Numerical results validate the proposed algorithm.

Stability analysis and design of droop control method in dq frame for connection in parallel of distributed energy resources

Droop control method is usually used when distributed energy sources are connected in parallel. The absence of communications between the distributed energy resources and its flexibility are some of its advantages. Moreover, a fictitious impedance can be added which improves the performance of the original technique. This fictitious impedance has to be properly designed in order to obtain a good stability and performance of the system. On the other hand, a restoration control that brings frequency and voltage amplitude of the microgrid to their nominal values is used in some cases. In this article, a linear model of a droop controlled microgrid with fictitious impedance and restoration control is implemented. Thanks to this linear model, an optimal fictitious impedance can be designed. Moreover, the influence of a proposed restoration control on the whole system can be studied. This way, the dynamic of the restoration control can be properly chosen. The stability as well as nominal values of frequency and voltage amplitude are guaranteed. Simulation results of the system confirm the validity of the proposed design.

Implementation of an electrical micro-grid through matrix converters connected in parallel

The matrix converter (MC) arouses a growing interest because it provides many advantages. On the other hand, the association of these converters in parallel makes the operation of the system operation more reliable and offers the possibility of creating electrical micro-grids. This article presents a parallel association of MCs by droop parallelization technique, which allows the control of several parallel MCs without needing communication between them. This configuration also offers the possibility to achieve an even load sharing. The obtained results demonstrate the feasibility of this technique.

Analysis and modelling of IGBTs parallelization fundamentals

In some power electronic applications, with high current and voltage ranges, discrete devices are not enough unless parallelization techniques are employed. IGBTs are one of the most common and widespread power electronic semiconductors, to make a parallel design with them, either as a discrete devices, dies, individual cells or power modules, it is necessary to know their static and dynamic behaviour. Besides, operation temperature, device parameter tolerances, driver circuit and power layout, as well as different parasitic inductance also affect its performance. The objective of this article is to show and model how all the aforementioned parameters affect the behaviour and performance of a parallelized IGBT, and highlight the design keys for a successful parallelized design.