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One of the challenges posed by renewable energies is the stabilization of parameters related to the quality of electrical energy. This study demonstrates the existence of a relationship between input blocks of hydropower and the variation of the fundamental frequency of the electricity grid. By mapping production data provided by the Spanish Electric Network with frequency measured in the laboratory, it is shown that gradients of hydropower are correlated with frequency fluctuations for certain characteristic times. Considering hourly instances of energy input, the study compares two methods for calculating hydropower gradients (linear regression and pseudo-linear regression) and two methods for calculating local frequency extrema (the "specular inertia" method and analysis by comparison with the moving average) in order to corroborate the results. [ABSTRACT FROM AUTHOR]

There is a prolific literature on the mitigation of cloud-induced photovoltaic fluctuations as a key objective for the effective grid integration of this renewable energy capacity. The meteorological context is of high relevance in such a problem, but it is frequently analysed separately from electrical considerations. However, a few studies have combined both sides of the problem, thus providing valuable references for examining their interdependencies. Therefore, this review focuses on this set of studies to explore the use of meteorological information in the analysis of cloud-induced photovoltaic transients in terms of scales, elements, and objectives under consideration. This examination shows the dependence of the results on the chosen context, allowing for the identification of the strengths and weaknesses of each approach. On this basis, some recommendations for future work are drawn, such as the use of spatiotemporal descriptions of cloud passage, description of the meteorological scenario for an adequate interpretation of results, and necessity of holistic approaches to integrate advances from the meteorological and electrical perspectives of the problem. [Display omitted] • Lack of meteorological information in cloud-induced PV transient analysis. • Meteorological context has significant impact on results. • Cloud passages' spatiotemporal descriptions are necessary for realistic estimations. • Integration of meteorological and electrical advances needed for complete solutions. [ABSTRACT FROM AUTHOR]

The interconnected modern smart grid has resulted in several new power quality (PQ) disturbances that affect the frequency stability requirements in industrial power systems. Ranging between 50 ± 0. 1 Hz for interconnected networks, and even within the European synchronous area, the frequency fluctuates mainly because of the primary control. In fact, owing to the development of distributed resources (e.g. renewable energies), not all generation units are accessible, and are controllable in a few network nodes. This variability, even between nearby locations, triggers the need for a specific measurement strategies, based on an absolute reference and also conceived for monitoring PQ disturbances. This work proposes an easy-to-implement GPS-traceable method that allows the measurement of frequency with better accuracy than that required by the current regulation for interconnected networks. This work explains the measurement methodology, characterising the uncertainty by using ISO JCGM 100. For the purpose of testing and validation, three experiments were conducted: computer-designed, instrument-triggered lab disturbances, and a comparison vs. PMU performance, using real-life signals. The results showed that these experiments offered better performance with improved uncertainty. [Display omitted] • Joint characterization of accuracy and frequency stability. • GPS-referenced reliability monitoring of bulk system and power delivery. • Measurement procedure, UTC synchronized and with accuracy up to 100 ppm. • Alternative to PMUs for measuring the frequency in accordance with the (IEC). • Method without DAQ-board using zero-crossing and GPS. [ABSTRACT FROM AUTHOR]