In the last years there has been a considerable increase in electricity consumption and
generation from renewable sources, especially wind and solar photovoltaic. This phenomenon has
increased the risk of line saturation with the consequent need of increasing the capacity of some power
lines. Considering the high cost and the time involved in installing new power lines, the difficulty in
acquiring tower sites and the related environmental impacts, some countries are considering to replace
conventional conductors with HTLS (High-Temperature Low-Sag) conductors. This is a feasible and
economical solution. In this paper a numerical-FEM (Finite Element Method) approach to simulate the
temperature rise test in both conventional and high-capacity substation connectors compatible with HTLS
technology is presented. The proposed coupled electric-thermal 3D-FEM transient analysis allows
calculating the temperature distribution in both the connector and the conductors for a given current profile.
The temperature distribution in conductors and connectors for both transient and steady state conditions
provided by the proposed simulation method shows good agreement with experimental data.
Abomailek, B.; Riba, J.; Capelli, F.; Moreno-Eguilaz, J.M. IET generation, transmission and distribution Vol. 11, num. 8, p. 2124-2129 DOI: 10.1049/iet-gtd.2016.2061 Data de publicació: 2017-06-01 Article en revista
Molina, J.; Mesas, J. J.; Mesbahi, N.; Sainz, L. IET generation, transmission and distribution Vol. 11, num. 4, p. 1063-1071 DOI: 10.1049/iet-gtd.2016.1696 Data de publicació: 2017-03-09 Article en revista
Energy saving policies have boosted the use of light emitting diode (LED) lamps in distribution networks. These lamps are non-linear loads which inject harmonic currents into the distribution system, which has led to a decrease in the system power quality. Study of the modelling of these lamps would allow the prediction of harmonic emissions into distribution systems. This study presents a frequency-domain LED lamp model for harmonic emission calculation, together with a simple estimation procedure for model parameter determination from experimental measurements. Both were validated by laboratory tests. Finally, an application illustrates the effect of widespread use of LED lamps in a typical distribution system and allows LED lamp models to be compared.
Rouzbehi, K.; Zhang, W.; Candela, J.; Luna, A.; Rodriguez, P. IET generation, transmission and distribution Vol. 11, num. 3, p. 750-758 DOI: 10.1049/iet-gtd.2016.0665 Data de publicació: 2016-10-11 Article en revista
Multi-terminal dc (MTDC) grids are expected to be built and experience rapid expansion in the near future as they have emerged as a competitive solution for transmitting offshore wind generation and overlaying their ac counterpart. The concept of inertia sharing for the control and operation of MTDC grids, which can be achieved by the proposed unified reference controller. The control objectives of the MTDC grids voltage source converter (VSC) stations are no longer limited to the stabilisation of MTDC grid, instead, the requirements of ac side are also met. The interaction dynamics between the ac and dc grid is analysed to illustrate the proposed concept. In addition, the voltage source converter stations can work in different operation modes based on the proposed unified control structure, and can switch among the operation modes smoothly following the secondary control commands. Simulation results exhibit the merits and satisfactory performance of the proposed control strategy for stable MTDC grid operation.
Aeronautical ground lighting (AGL) systems are single-phase series circuits where constant current regulators supply transformers and luminaires. These systems provide visual reference to aircraft during airport operations. There is a lack of AGL system models and measurements in the literature to study AGL system behaviour and predict their response to electrical events and future technological changes. The study contributes to AGL system modelling with an equivalent circuit useful to study AGL system concerns by Matlab/Simulink simulations. It also presents field measurements taken at Reus airport (Catalonia, Spain) for the validation of the proposed model and understanding of AGL system behaviour in the event of luminaire failure.
Monadi, M.; Koch-Ciobotaru, C.; Luna, A.; Candela, J.; Rodriguez, P. IET generation, transmission and distribution Vol. 10, num. 14, p. 3517-3528 DOI: 10.1049/iet-gtd.2016.0183 Data de publicació: 2016-06-28 Article en revista
Voltage source converters (VSCs) are highly vulnerable to DC fault current; thus, protection is one of the most important concerns associated with the implementation of multi-terminal VSC-based DC networks. This paper proposes a protection strategy for medium voltage DC (MVDC) distribution systems. The strategy consists of a communication-assisted fault location method and a fault isolation scheme that provides an economic, fast and selective protection by means of using the minimum number of DC circuit breakers (DCCBs). This paper also introduces a backup protection which is activated if communication network fails. The effectiveness of the proposed protection strategy is analyzed through real-time simulation studies by use of the hardware in the loop (HIL) approach. Furthermore, the effects of fault isolation process on the connected loads are also investigated. The results show that the proposed strategy can effectively protect multi-terminal DC distribution networks and VSC stations against different types of faults.
Suul, J.; D'Arco, S.; Rodriguez, P.; Molinas, M. IET generation, transmission and distribution Vol. 10, num. 6, p. 1315-1326 DOI: 10.1049/iet-gtd.2015.0879 Data de publicació: 2016-05-12 Article en revista
This paper demonstrates how the range of stable power transfer in weak grids with voltage source converters (VSCs) can be extended by modifying the grid synchronisation mechanism of a conventional synchronous reference frame phase locked loop (PLL). By introducing an impedance-conditioning term in the PLL, the VSC control system can be virtually synchronised to a stronger point in the grid to counteract the instability effects caused by high grid impedance. To verify the effectiveness of the proposed approach, the maximum static power transfer capability and the small-signal stability range of a system with a VSC HVDC terminal connected to a weak grid are calculated from an analytical model with different levels of impedance-conditioning in the PLL. Such calculations are presented for two different configurations of the VSC control system, showing how both the static power transfer capability and the small-signal stability range can be significantly improved. The validity of the stability assessment is verified by time-domain simulations in the Matlab/Simulink environment.
Rakhshani, E.; Remon, D.; Cantarellas, A.M.; Rodriguez, P. IET generation, transmission and distribution Vol. 10, num. 6, p. 1458-1469 DOI: 10.1049/iet-gtd.2015.1110 Data de publicació: 2016-05-12 Article en revista
Due to increasing level of power converter-based component and consequently the lack of inertia, automatic generation control (AGC) of interconnected systems is experiencing different challenges. To cope with this challenging issue, a derivative control-based virtual inertia for simulating the dynamic effects of inertia emulations by HVDC (high-voltage direct current) interconnected systems is introduced and reflected in the multi-area AGC system. Derivative control technique is used for higher level applications of inertia emulation. The virtual inertia will add an additional degree of freedom to the system dynamics which makes a considerable improvement on first overshoot responses in addition to damping characteristics of HVDC links. Complete trajectory sensitivities are used to analyse the effects of virtual inertia and derivative control gains on the system stability. The effectiveness of the proposed concept on dynamic improvements is tested through Matlab simulation of two-area test system for different contingencies.
This study presents the basic features of a Monte Carlo approach for reliability evaluation of distribution systems without embedded generation using parallel computation. The test system is represented by means of a three-phase model that includes protective devices and is simulated during one year. The procedure has been implemented in an open environment in which OpenDSS is driven from MATLAB. The document includes a detailed description of the procedure, and some results derived from the simulation of an overhead distribution test system.