Electricity quality issues when connecting renewable sources to a distribution network

Zvýšené povědomí o životním prostředí podpořilo využívání obnovitelných zdrojů energie jako alternativních zdrojů pro výrobu čisté a zelené energie. Větrná energie je v posledních letech významnou obnovitelnou energií.V diplomové práci je prezentován vliv výrobny elektřiny využívající obnovitelné zdroje energie připojené na distribuční síť. Tato diplomová práce předkládá kompletní simulační analýzu napěťového rozvodu 22kV pomocí simulačního softwaru E-Vlivy před a po připojení větrné elektrárny do distribuční soustavy v Libereckém kraji. Graficky byla charakterizována analýza zatížení a profil napětí v každém uzlu distribučního systému vysokého napětí.Increased environmental awareness has encouraged the exploitation of renewable energy as the alternative sources to produce clean and green energy. Wind energy is the significant renewable energy in the recent years. The Impact of renewable energy sources connected to distribution network has been presented in detail. This master thesis presents a complete simulation analysis of medium voltage distribution line 22 kV with the help simulation software E-Vlivy before and after connection of WPP into the distribution system in Liberecký Region. The load flow analysis and voltage profile at each node of medium voltage distribution system has been characterized graphically

Complementary Power Control for Doubly Fed Induction Generator-Based Tidal Stream Turbine Generation Plants

The latest forecasts on the upcoming effects of climate change are leading to a change in the worldwide power production model, with governments promoting clean and renewable energies, as is the case of tidal energy. Nevertheless, it is still necessary to improve the efficiency and lower the costs of the involved processes in order to achieve a Levelized Cost of Energy (LCoE) that allows these devices to be commercially competitive. In this context, this paper presents a novel complementary control strategy aimed to maximize the output power of a Tidal Stream Turbine (TST) composed of a hydrodynamic turbine, a Doubly-Fed Induction Generator (DFIG) and a back-to-back power converter. In particular, a global control scheme that supervises the switching between the two operation modes is developed and implemented. When the tidal speed is low enough, the plant operates in variable speed mode, where the system is regulated so that the turbo-generator module works in maximum power extraction mode for each given tidal velocity. For this purpose, the proposed back-to-back converter makes use of the field-oriented control in both the rotor side and grid side converters, so that a maximum power point tracking-based rotational speed control is applied in the Rotor Side Converter (RSC) to obtain the maximum power output. Analogously, when the system operates in power limitation mode, a pitch angle control is used to limit the power captured in the case of high tidal speeds. Both control schemes are then coordinated within a novel complementary control strategy. The results show an excellent performance of the system, affording maximum power extraction regardless of the tidal stream input.This work was supported in part by the University of the Basque Country (Universidad del Pais Vasco UPV/ Euskal Herriko Unibertsitatea EHU) through Project PPG17/33 and by the MINECO through the Research Project DPI2015-70075-R (MINECO/FEDER, EU). (Ministerio de Economa, Industria y Competitividad/Fondo Europeo de Desarrollo Regional, European Union). The authors would like also to thank the anonymous reviewers for the useful comments that have helped to improve the initial version of this manuscript