No abstract

The dynamic features of microgrid operation, such as on-grid/off-grid operation mode, the intermittency of distributed generators, and its dynamic topology due to its ability to reconfigure itself, cause misfiring of conventional protection schemes. To solve this issue, adaptive protection schemes that use robust communication systems have been proposed for the protection of microgrids. However, the cost of this solution is significantly high. This paper presented an intelligent fault detection (FD) system for microgrids on the basis of local measurements and machine learning (ML) techniques. This proposed FD system provided a smart level to intelligent electronic devices (IED) installed on the microgrid through the integration of ML models. This allowed each IED to autonomously determine if a fault occurred on the microgrid, eliminating the requirement of robust communication infrastructure between IEDs for microgrid protection. Additionally, the proposed system presented a methodology composed of four stages, which allowed its implementation in any microgrid. In addition, each stage provided important recommendations for the proper use of ML techniques on the protection problem. The proposed FD system was validated on the modified IEEE 13-nodes test feeder. This took into consideration typical features of microgrids such as the load imbalance, reconfiguration, and off-grid/on-grid operation modes. The results demonstrated the flexibility and simplicity of the FD system in determining the best accuracy performance among several ML models. The ease of design's implementation, formulation of parameters, and promising test results indicated the potential for real-life applications.Energies 2020, 13, 1223 2 of 21 as improved reliability, integration of renewable energies, reduction of network losses, and better voltage profile [7]. Nevertheless, microgrids present new challenges such as bidirectional power flow, considerable variations on fault currents levels, as well as power intermittency and quality issues, and additionally possible network reconfiguration, due to the presence of renewable energy sources [8]. Protection systems inside the distribution grid are particularly affected because they are based on the principle of overcurrent and unidirectional power flow [9]. Thus, traditional overcurrent protection schemes do not adequately protect microgrids [10].Several approaches have been proposed in the literature to deal with microgrid protection [11]. These protection schemes can be classified into three classes: external protection, adaptive protection, and fault detection. The external protection (EP) approach uses additional equipment such as reactances, super-capacitors, or fault current limiters (FCL) for preventing misfiring of the protection devices [12][13][14]. However, these solutions lack flexibility and, therefore, are not suitable for microgrids, where topology changes and DER connection/disconnection is possible [15]. The adaptive protection (AP) approach works online to dynamically modify protec...

Modern fault location methods are robust; however, they depend strongly on the availability of the measurements given by Distributed Energy Resources (DER). If the communication or synchronism of this information is lost, the fault location is not possible. This paper proposes an adaptive impedance-based fault location algorithm for active distribution systems. The proposal combines information provided by Intelligent Electronic Devices (IEDs) located at the substation, the knowledge of the network topology and parameters, as well as the distributed power sources, to estimate the fault location. Its adaptive feature is given by the use of a Distributed Energy Resources (DER) electrical model. This model is used to estimate the DER current contribution to the fault, in case the information provided by a local IED is not available. The method takes two types of DER technologies into account: Inverter non-interfaced DER (INIDER) and Inverter-interfaced DER (IIDER). The proposed method is validated on a modified IEEE 34-node test feeder, which was simulated with ATP/EMTP. The results obtained using the IEDs information, presented a maximum error of 0.8%. When this information is not available, the method’s performance decreases slightly, obtaining a maximum error of 1.1%. The proposed method showed better performance when compared with two state of the art methods, indicating potential use for real-life applications.

No abstract

ABSTRACT:This paper presents an analysis on the influence of anthropogenic phenomena over the lightning activity in large cities located in mountainous region of tropical zone, specifically in Bogotá City. Some preliminary results show an increase of lightning activity between 33% and 340% for the period under study (2007)(2008)(2009)(2010)(2011)(2012), when a comparison between urban and rural adjacent zone is carried out. An additional analysis of the influence of pollution on lightning activity was also carried out; this analysis shows that there is a tendency of correlation between number of strokes and particulate matter (PM 10 ) for the zones under study with the highest levels of contamination of the city. In order to achieve the goals of this study, data from one of the Colombian Lightning Location Systems (SID) and the monitoring network of air quality of Bogotá were used. The results are consistent with other studies carried out in different cities of the world. RESUMEN:El siguiente estudio realiza un análisis sobre la influencia de fenómenos antropogénicos en la actividad de rayos para la ciudad de Bogotá. Los resultados muestran que hay un incremento en la actividad de rayos entre el 33%-340% para el periodo de 2007-2012, cuando se compara la zona urbana de Bogotá con una zona rural adyacente. También se realizó un análisis para observar la influencia de la polución de la ciudad, sobre los rayos. Los resultados muestran que hay una tendencia entre el número de rayos y el material particulado para las zonas con mayores niveles de contaminación de la ciudad. Para realizar el estudio fueron utilizados los datos de la red de localización de rayos -SID y para la información de niveles de polución se utiliza la red de monitoreo de calidad del aire de Bogotá. Los resultados son consistentes con otros estudios llevados a cabo en otras ciudades del mundo. Lightning activity over large cities located in mountainous tropical zones and its relationship with particulate matter PM 10 distribution-the Bogotá City Case.Análisis de la actividad de rayos sobre grandes ciudades localizadas en zona montañosa tropical y su relación con la distribución de material particulado PM 10 . Caso Bogotá.