Browsing by Author "Fortunato, Carlos"
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- A computer-based testing system to evaluate protective relays as a tool in power system protection educationPublication . Martins, L. Sousa; Fortunato, Carlos; Pires, V. FernãoTeaching power system relaying is a fundamental issue in a power system high-level course. However, for an effective instruction of this topic an experience with real equipments can be considered as fundamental. To achieve this purpose, in this paper a new approach for the practical learning of power system relaying is presented. This consists of a computer-based testing system of relay-operating characteristic. Different relay types and developed specific software are also an important piece of the laboratory practice. Using this system it is possible to understand the performance and limitations of different protective relay systems and to test a real relay disoperation. The benefit of using this system is not available through traditional lectures and textbooks.
- Current differential line protection using a pattern recognition methodPublication . Pires, V. Fernão; Fortunato, CarlosThis paper presents a new approach to a numerical current differential protection for the transmission lines. The current differential algorithm uses a pattern recognition method. First the acquired current signals are transformed into “dqo” components by applying the Park transformation. The transformed currents will originate typical patterns according the fault type. Using a pattern recognition algorithm the different faulty conditions are identified. Several tests under different fault conditions were performed. The obtained results allow verifying the effectiveness of the proposed approach.
- A current differential line protection using a synchronous reference frame approachPublication . Martins, L. Sousa; Fortunato, Carlos; Pires, V. FernãoThis paper presents a new approach for a current differential protection of the transmission lines. This approach is based on the Park transformation or ABC-dqo transformation. Using the ABC-dqo transformation the three phase quantities are transformed into a synchronous rotating reference frame. In this way, the line currents of the three phase system are measured and transformed into three dc components. So, immunity to problems such as sampling misalignment and time delay of the communication channel will be improved. Several test results are presented in order to show the effectiveness of the proposed approach.
- Distribution automation on LV and MV using distributed intelligencePublication . Melo, Francisco; Cândido, Carlos; Fortunato, Carlos; Silva, Nuno; Campos, Filipe; Reis, PauloNowadays, the electrical energy distribution network is considered to be a critical infrastructure in industrially developed societies. Its protection regarding safety and security threats is increasing awareness and concern.The fact that this infrastructure is geographically spread across large areas brings difficult technological challenges for fault management (real-time prevention, detection, precise location and isolation of anomalies). The distribution automation and fault location in the distribution network is a key task for any operator. Distribution Automation (DA) and electric network monitoring and sensing can reduce outage and repair times, optimise voltage profiles and improve asset management. Advanced DA processes real-time information from sensors, smart meters, Distributed Generation (DG) and network topology for fault location, automatic reconfiguration of feeders, voltage and reactive power optimisation. This paper addresses this subject and describes the technology and functionalities being implemented on a DA pilot project promoted by EDP Distribuição (EDP Group), Portugal and under InovGrid initiative together with EFACEC and Silver Spring Networks (SSN).
- Energy and quality of service management in wireless multimedia sensor networksPublication . Pereira, Paulo; Gonçalves, José; Grilo, António; Fortunato, Carlos; Nunes, Mário; Casaca, AugustoSensor networks are composed of resource constrained nodes that capture data from the environment, preprocess it and then transmit it to a sink node. This paper presents a scenario for monitoring an electricity distribution network, an energy analysis of the used sensor nodes and an intelligent energy and quality of service (QoS) manager. This manager continuously adapts the provided QoS according to the energy level of the nodes.
- Fast and secure automatic retrieval of data from multi-vendor devices - The portuguese experiencePublication . Louro, Miguel; Guisado, Jaime; Fortunato, Carlos; Cura, Carlos; Antunes, Bruno; Areias, Miguel; Grossinho, Miguel; Pereira, Luís Pinto; Pimenta, FernandoNowadays protection systems generate large amounts of useful data. The most important of which are the oscillographic records, because they allow: fault location estimation; validation of relay settings; validation of coordination among protections. This important information traditionally resided in the protection units and could only be retrieved through vendor proprietary software. Retrieving this information could be conducted in two ways: a specialized technician had to physically go to the substation (expensive solution); by use of a slow analog modem with a tendency to breakdown (especially in remote areas exposed to lightning strikes) and a high probability to stop working due to communication errors. Recently EDP has begun to equip all the substations with an IP network through optical fiber. This fast and reliable network, which is also intended for other application other than remote access, eliminates the communication constraints. Due to technological differences the substations were, for this purpose, separated in two groups: Substations with a modern protection system complying with IEC 61850; Substations with older protection units for which a pilotproject was conducted using the communications gateway Kalkitech SYNC2000. This device communicates with protection units from several vendors, using standardized (ex.: IEC61850) or proprietary protocols (ex.: ABB SPABUS), and has mechanisms for retrieving oscillographic records. The usage of standard tools such as FTP and file sync programs proved to be cost effective and reliable to get the information to a central location.
- Fault location in an electrical energy distribution infrastructure with a wireless sensor networkPublication . Fortunato, Carlos; Casaca, Augusto; Grilo, António; Santos, MiguelThis article presents a detailed analysis of the applicability of wireless systems in the localization of faults in the energy distribution network. The hwardware and software architectures of the envised sensor solution will also be described and finally, the integration of this system into Smart Grids will be discussed in terms of automatic fault analysis. A pilot system has been tested in a subset of the Portuguese energy distribution infrastructure operated by EDP Energias de Portugal. It presents a new approach to a fault locator system for the power network. The purpose is to obtain faster and more reliable information about the disruptions in the power distribution network and their location. Furthermore, the wireless sensors allow remote detection of medium and low voltage (MV/LV) power transformer hotspots in order to identify emerging malfunction as well as detection of intrusion in the MV/LV power transformers.
- Fault location in an electrical energy distribution infrastructure with a wireless sensor networkPublication . Fortunato, Carlos; Casaca, Augusto; Grilo, António; Santos, MiguelThis paper presents a detailed analysis of the applicability of wireless systems in the localization of faults in the energy distribution network. The hardware and software architectures of the envisaged sensor solution will also be described and finally, the integration of this system into Smart Grids will be discussed in terms of automatic fault analysis. A pilot system has been tested in a subset of the Portuguese energy distribution infrastructure operated by EDP Energias de Portugal. It presents a new approach to a fault locator system for the power network. The purpose is to obtain faster and more reliable information about the disruptions in the power distribution network and their location. Furthermore, the wireless sensors allow remote detection of medium and low voltage (MV/LV) power transformer hotspots in order to identify emerging malfunction as well as detection of intrusion in the MV/LV power transformers.
- A power amplifier system for testing of distance relay operating characteristicPublication . Marçal, Rui; Rodrigues, Ricardo; Fortunato, Carlos; Martins, L. Sousa; Pires, V. FernãoThis paper describes a power amplifier system for testing of distance relay operating characteristic. This power amplifier is based on two three phase inverters with a neutral wire. The output power currents and voltages are controlled by a sliding mode controller. A developed matlab/simulink digital simulator generates the test signals. This test signals are converted in current and voltage references using a microcontroller to connect the digital simulator to the power converter amplifier. Experimental results from a laboratory prototype are presented and discussed.
- Transmission lines protection based on the current eigenvalues differential conceptPublication . Pires, V. Fernão; Guerreiro, M.; Fortunato, Carlos; Martins, L. SousaThis work presents a new approach for a current differential protection of the transmission lines. The proposed approach is based on the Clarke-Concordia transformation and principal component analysis. First the acquired current signals are transformed into “αβo” components by applying the Clarke-Concordia transformation. This allows obtaining typical patterns. To identify these patterns a principal component analysis is performed. Several tests under different fault conditions were performed. The obtained results allow verifying the effectiveness of the proposed approach.