A. L. P. de Oliveira

Prospects of Voltage-Sourced Converters (VSC) applications in DC transmission systems

Fundamental changes are affecting the power transmission industry. Markets are being deregulated and liberalized, urbanization is continuing around the world accompanied by a constantly growing demand for energy and renewable energy sources are playing an increasingly important role. For these reasons, new and efficient solutions for power transmission are required. This paper will present the prospects and technology issues of the latest developments in Voltage-Sourced Converters (VSC) for advanced power transmission systems. A new technology Modular Multilevel Converters (MMC) will be described and all the benefits of the VSC for transmission systems enhancement will be highlighted.

Prospects of Voltage-Sourced Converters (VSC) applications in power transmission systems

Fundamental changes are affecting the power transmission industry. Markets are being deregulated and liberalized, urbanization is continuing around the world accompanied by a constantly growing demand for energy and renewable energy sources are playing an increasingly important role. For these reasons, new and efficient solutions for power transmission are required. This paper will present the prospects and technology issues of the latest developments in Voltage-Sourced Converters (VSC) for advanced power transmission systems. A new technology Modular Multilevel Converters (MMC) will be described and all the benefits of the VSC for transmission systems enhancement will be highlighted.

Evaluation of Distance Protection Performance applied on Series Compensated Transmission Lines using Real Time Digital Simulation

The protection of series compensated lines is considered to be one of the most difficult tasks for engineers. The series compensation affects the impedance measurement such that special considerations are necessary in the application of distance protection. In order to evaluate the performance of distance protective relays that will be applied in 500 kV Brazilian transmission system, real time closed-loop digital simulations were realized. The closed-loop testing approach enables the evaluation of not only the protective relay but also the response of the system to the relays action. Several complex situations were simulated and analyzed. This provided an opportunity to optimize the relays settings and protection scheme, therefore saved time during commissioning and assurance of satisfactory performance. The main objective is to present an evaluation of distance protection when applied to protect series compensated transmission lines, presenting not only the tripping times, but also verifying all the performance and functionality of a modern protection system.

Full range active AC Filter with multilevel IGBT converter for transmission and distribution systems

The first active AC filter at an HVDC station was installed by Siemens in 1998 in the HVDC Converter Station of Tjele, in Denmark as a demonstration project. This active filter used a 0.6 MVA IGBT converter. This paper introduces the new full range active AC filter developed as a new standard product by the same company, four of them were commissioned at the converter stations of the Neptune Regional Transmission System USA in 2007. These active filters have a 22 MVA multilevel IGBT converter and open new possibilities for harmonic mitigation at HVDC stations but also in other AC applications where such ratings are required.

Fixed series compensation monitoring system

Fixed Series Compensation (FSC) employs capacitors to compensate the inductive reactance of transmission lines, being a highly effective and economical means of improving power transfer. A Fixed Series Compensation Monitoring System has as objective the knowledge of the actual physical state of this FACTS (Flexible AC Transmission Systems) system and diagnose the evolution of components damage, so that it is possible to foresee the need of intervention (supply interruption) and preventive maintenance in the monitored equipment. The main purpose of this paper is to present the FSC Monitoring System, a tool for preventive maintenance of the equipments that compose the FSC, minimizing risks of blackouts in a Power Transmission System.

Fixed series compensation protection evaluation using transmission lines faults simulations

The power demands of Brazilian national industries need an economical solution to increase power transmission capacity of existing transmission lines. Due to environmental and economical difficulties for construction of new power transmission lines, the use of fixed series compensation (FSC) has turned into a common practice of power transmission companies in Brazil. The FSC is presented as the best choice, because not only does it make possible to increase power transmission capacity as well as it stabilizes the interconnected energy nets through reduction of the impedance of the transmission line. The main purpose of this work is to present the FSC protection evaluation installed at Rio Verde 230 kV substation with 216 MVAr (FURNAS Centrais Eletricas S.A. - Brazilian Power Transmission Utility). This evaluation will be realized simulating faults internal and external to the 230 kV transmission line where the FSC were installed. The final conclusion of the work is to present the importance of the FSC to a transmission system and a complete evaluation of the FSC protection, observing the dimensioning and the situations that this protection operates in the transmission system with the purpose to keep the energy flow against faults due to lightning discharges and other causes.

Image processing as an integration tool between a dam safety system and Smart Grids

The Smart Grid resilience in power systems could be improved thanks to remote monitoring of civil structures existing at concrete and earth-filled dams, which indicates any atypical behavior of these structures. Among the various sensors and transducers used, the direct and inverted pendulums present an additional challenge. These instruments are widely used in hydroelectric reservoirs to monitor minor displacements in the concrete structures by the measurement of the pendulums degree of inclination according to the X and Y references set which will reflect the amount of displacement. In this paper, a system capable of performing automated readings of the pendulum wires inclination, through the image processing technique, is presented. A processing methodology combining the calculation of the x component, the gradient signal and the Hough transform was adopted for this purpose.

Advantages of the technical evolution of protection, control and supervision system applied to fixed series compensation

The use of flexible alternating current transmission systems (FACTS) is well known because it provides a lot of benefits to improve the power transfer capacity in transmission lines, as well as power system stability. The simplest and most cost-effective type of FACTS is provided by fixed series compensation (FSC). This paper will present the technical innovations, the advantages and the progess obtained in Brazilian engineering through development of the protection, control and supervision system (PCSS) applied to the FSCs installed on the Mato Grosso State Transmission System (ELETRONORTE Power Transmission Utility - Brazil) at Barra do Peixe 230 kV substation. The paper will describe how the development of PCSS engineering and FACTS project management are making possible to generate high quality and efficient power transmission solutions to the Brazilian Power Transmission System.

Subsynchronous resonance analysis after Barra do Peixe 230 kV Fixed Series Compensations installation at 230 kV Mato Grosso transmission system (Brazil)

The use of fixed series compensation is well known because it provides a lot of benefits to improve the power transfer capacity in transmission lines, as well as power system stability. However, the presence of capacitors in series applied on power transmission system can result in appearance of the subsynchronous resonance phenomena. This technical paper will present the subsynchronous resonance analysis after the installation of 03 (three) fixed series compensations (35 MVAr, 120 MVAr and 37 MVAr) at the Barra do Peixe 230 kV Substation at 230 kV Mato Grosso Transmission System (ELETRONORTE Power Transmission Utility - Brazil). The analysis was carried out using power system simulations realized with PSStrade NETOMAC software. The paper will first describe the methodology used in the analysis, discuss limitations and focus on the possibility of resonance condition on the power transmission system.

Numerical distance protection performance analysis in short and long transmission lines using real time digital simulation

The main purpose of this work is to present a performance analysis of numerical distance protection applied in high voltage transmission lines, more specifically in the 500 kV transmission lines of CEMIG (Energy Company of Minas Gerais - Brazilian Energy Utility) between the Vespasiano 2 - Neves 1 (short line - 23.9 km) and Vespasiano 2 - Mesquita (long line - 148.6 km) substation. The need for energy reliability and quality in power transmission resulted in the choice for multifunction numeric protective relays in transmission lines that could assure the equipments and transmission lines security with the continuity and stability warranty for CEMIGpsilas transmission system. Simulations and test were requested to analyze the numeric distance relays behavior that would be installed in the Vespasiano 2, Neves 1 and Mesuita 500 kV Substations. The paper will realize the performance analysis and evaluation of the same numerical distance protection applied in both transmission lines using real time digital simulation.