Browsing by Author "Martins, I. E."
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- Control of distributed power flow controllers using active power from homopolar line currentsPublication . Martins, I. M.; Silva, J. F. A.; Pinto, S. F.; Martins, I. E.Flexible AC Transmission Systems (FACTS) devices can be used for power flow control in AC transmission grids, improving power line utilization and performance. Nowadays, Unified Power Flow Controllers (UPFC) are one of the most useful FACTS, allowing the simultaneous control of the bus voltage and line active and reactive power. However, due to high costs and reliability concerns, the utilization of this technology has been limited in such applications. The concept of Distributed FACTS (DFACTS) and Distributed Power Flow Controller (DPFC) was recently introduced as a low coast alternative for power flow control. This paper presents a distributed power flow controller that uses third-harmonic frequency currents transmitted through the line to independently control active and reactive power flow at fundamental frequency. Simulations were carried in the Matlab/Simulink environment. © 2012 IEEE.
- Electromagnetic hybrid active-passive vehicle suspension systemPublication . Martins, I. E.; Esteves, J.; da Silva, F. P.; Verdelho, P.The suspension systems currently in use can be classified as passive, semi-active and active. The passive suspension systems are the most commonly used due to their low price and high reliability. However, this system can not assure the desired performance from a modem suspension system An important improvement of the suspension performance is achieved by the active systems. Nevertheless, they are only used in a very reduced number of automobile models because they are expensive and complex. Another disadvantage of active systems is the relatively high energy consumption. The use of electromagnetic linear actuators is an alternative for the implementation of active suspensions. Moreover, this solution has the advantage of the suspension energy recovery. In spite of the materials development, the electromagnetic actuators are yet expensive to produce. In this paper it is proposed an hybrid suspension system which combines the simplicity of the passive dampers with the performance of an electromagnetic active suspension. Maintaining the passive damper, it is possible to keep the performance of the active suspension, but using a smaller electromagnetic actuator.
- Permanent-magnets linear actuators applicability in automobile active suspensionsPublication . Martins, I. E.; Esteves, J.; Marques, G. D.; da Silva, F. P.Significant improvements in automobile suspension performance are achieved by active systems. However, current active suspension systems are too expensive and complex. Developments occurring in power electronics, permanent magnet materials, and microelectronic systems justifies analysis of the possibility of implementing electromagnetic actuators in order to improve the performance of automobile suspension systems without excessively increasing complexity and cost. In this paper, the layouts of hydraulic and electromagnetic active suspensions are compared. The actuator requirements are calculated, and some experimental results proving that electromagnetic suspension could become a reality in the future are shown.
- Sliding mode active and reactive power decoupled control for Distributed Power Flow ControllersPublication . Martins, I. M.; Silva, F. A.; Pinto, S. F.; Martins, I. E.Unified Power Flow Controllers (UPFC) are one of the most useful Flexible AC Transmission Systems (FACTS). They can be used for power flow control in AC transmission grids, allowing simultaneous control of the bus voltage and line active and reactive power. However, due to high costs and reliability concerns, UPFCs have experimented limited use in such applications. Recently, the concepts of Distributed FACTS (DFACTS) and Distributed Power Flow Controller (DPFC) have been introduced as a low cost, high reliability alternative for power flow control. However, DPFCs present cross-coupled (interdependent) and limited regulation of active and reactive power. Therefore, this paper contributions include: (1) a third-harmonic output voltage controller for a full-bridge converter, able to extract active power from third-harmonic currents, to maintain the converter DC voltage constant; (2) DPFC sliding-mode controllers to simultaneously inject active and reactive power at the fundamental frequency, to achieve cross-decoupled (independent) control of active and reactive power flow; (3) applying the sliding mode controlled DPFC to a part of the Portuguese distributed generation and transmission network under study. To provide the required active power to each DPFC device, a PI controlled full-bridge converter acting as a virtual resistance is proposed to extract active power from zero-sequence harmonic frequency currents injected into the line. DPFC models including semiconductor switching, together with line transmission models, were simulated in Matlab/Simulink environment and in PSCAD for comparison purposes. Simulations results show the effectiveness of the full-bridge converter sliding mode controllers in decoupling P and Q control while simultaneously extracting active power from the injected zero-sequence injected currents. (C) 2014 Elsevier B.V. All rights reserved.
- Transformer and LCL Filter Design for DPFCsPublication . Martins, I. E.; Silva, J. F. A.; Pinto, S. F.; Martins, I. E.Flexible AC Transmission Systems (FACTS) can be used for power flow control in AC transmission grids, allowing simultaneous control of the bus voltage and line active and reactive power. However, due to high costs and reliability concerns, the application of this technology has been limited in such applications. Recently, the concept of Distributed FACTS (DFACTS) and Distributed Power Flow Controller (DPFC) has been introduced as a low cost high reliability alternative for power flow control. This paper presents the design of a coupling transformer and a LCL filter for DPFC devices. To extract the electromagnetic energy from the transmission line a transformer with a single turn primary is designed and optimized. A third-order LCL filter is used to guarantee high order harmonics filtering. Simulations results are presented and discussed.