This paper offers a systematic literature review of real-time detection and classification of Power Quality Disturbances (PQDs). A particular focus is given to voltage sags and notches, as voltage sags cause huge economic losses while research on voltage notches is still very incipient. A systematic method based on scientometrics, text similarity and the analytic hierarchy process is proposed to structure the review and select the most relevant literature. A bibliometric analysis is then performed on the bibliographic data of the literature to identify relevant statistics such as the evolution of publications over time, top publishing countries, and the distribution by relevant topics. A set of articles is subsequently selected to be critically analyzed. The critical review is structured in steps for real-time detection and classification of PQDs, namely, input data preparation, preprocessing, transformation, feature extraction, feature selection, detection, classification, and characterization. Aspects associated with the type of disturbance(s) addressed in the literature are also explored throughout the review, including the perspectives of those studies aimed at multiple PQDs, or specifically focused on voltage sags or voltage notches. The real-time performance of the reviewed tools is also examined. Finally, unsolved issues are discussed, and prospects are highlighted.

The integration of wind energy into power systems has intensified as a result of the urgency for global energy transition. This requires more accurate forecasting techniques that can capture the variability of the wind resource to achieve better operative performance of power systems. This paper presents an exhaustive review of the state-of-the-art of wind-speed and -power forecasting models for wind turbines located in different segments of power systems, i.e., in large wind farms, distributed generation, microgrids, and micro-wind turbines installed in residences and buildings. This review covers forecasting models based on statistical and physical, artificial intelligence, and hybrid methods, with deterministic or probabilistic approaches. The literature review is carried out through a bibliometric analysis using VOSviewer and Pajek software. A discussion of the results is carried out, taking as the main approach the forecast time horizon of the models to identify their applications. The trends indicate a predominance of hybrid forecast models for the analysis of power systems, especially for those with high penetration of wind power. Finally, it is determined that most of the papers analyzed belong to the very short-term horizon, which indicates that the interest of researchers is in this time horizon.

Harmonic distortion in residential distribution networks is increasing due to the penetration of multiple nonlinear loads, including modern technologies such as plug-in electric vehicles and energy efficient lighting (e.g., compact fluorescent and LED lamps). The distributed nature of these loads introduces complexity in the analysis of harmonic propagation. Therefore, more sophisticated tools are needed to investigate this issue, on the basis of formerly established methodologies. This paper presents a literature review on the assessment of the harmonic distortion in residential distribution networks. To that end, bibliographic data of the most representative publications related to the topic were obtained. From these data, a novel citation analysis method was developed to construct a chronologically organized direct citation network. Based on the temporal evolution of the citation network, the aforementioned issue is presented, identifying lines of research and proposed methodologies. From the analysis of the literature review, the stages for modeling and simulating harmonic propagation are identified and described. The principal aspects to be addressed for obtaining an accurate harmonic analysis are also identified and detailed, namely, harmonic interaction, diversity, unbalance, and uncertainty. Finally, main conclusions are highlighted.

Large-scale penetration of power electronic-based loads is a concern in modern distribution networks due to the increase in harmonic distortion. Harmonic analysis in frequency-domain is suitable to deal with this problem due to the high computational efficiency. This type of analysis relies on the accuracy of nonlinear load models. This paper presents the development of a coupled admittance matrix model, able to characterize the interaction between harmonic voltages and currents, for a single-phase rectifier. The model was obtained by carrying out simulations in Matlab/Simulink. The dependence of the admittances on the phase angles of the harmonic voltages is considered by means of the tensor representation of the matrix. Besides, the effect of the variation of voltage distortion magnitude is analyzed. One thousand cases with different voltage distortions were carried out to test the model. The validation is achieved by comparing the aforementioned results with the respective simulations in time-domain.

Plug-in Electric Vehicles (PEVs) are progressively penetrating world markets. A significant impact on harmonic distortion in distribution networks is expected due to large-scale charging of PEVs at homes. Therefore, models that accurately predict the individual current injections are needed to perform harmonic studies, in particular frequency domain models such as those based on Frequency Coupling Matrices (FCM). In this paper, Fourier descriptors are used to estimate and compare the FCMs of a commercially available on-board PEV charger. Two models were calculated for two different supply reference conditions, namely, a sinusoidal voltage with no distortion, and a flat-top voltage. To that end, extensive laboratory measurements were carried out. Results show similar values in the parameterized admittances for both reference conditions. These results indicate a wide linear range in the coupled Norton model for this load, and should be probably attributable to the active power factor correction topology of the charger.

The use of Fourier descriptors (FD) for the assessment of frequency coupling matrices (FCM) of power electronic devices is considered. After some recalls on FDs, FCM approach is discussed showing how the matrices elements can be built basing on the use of maximum two FDs under linearity hypothesis. Then, a non-linearity index that allows to check the validity of the assumed “linearity hypothesis” and to quantify the obtainable accuracy is introduced. Numerical simulations on two very simple non linear circuits are performed to show the sensitivity of the FCM elements to magnitude and phase angle variation of the background harmonic distortion using FDs and the usefulness and the behavior of the non linearity index.