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The objective of this paper is to compare the performance of thyristor-controlled reactors (TCR) and shunt-connected PWM voltage source inverters (PWM-VSI) for compensation of flicker caused by arc furnaces. First of all, arc-furnace principles are presented in order to explain the main characteristics of the problem. Secondly, traditional TCR control are analyzed. An improved measuring procedure is suggested to enhance TCR performance showing that it achieves faster compensation than more traditional methods. Thirdly, PWM-VSI control for flicker compensation is described in detail using Park's transformation. The analysis shows how real and reactive power control can be decoupled. Continuous-time and discrete-time models are considered. Finally, a TCR control and a PWM-VSI control are compared by simulation using data and measurements from a real arc-furnace installation. The analysis considers three different periods of the production cycle: a) bore-down, b) fusion, and c) refining. It is clear from the results obtained that a shunt-connected PWM-VSI is better than a TCR for flicker compensation. This can be easily justified noting that the bandwidth of the PWM-VSI control system is far better than that of the TCR control. However, the control system for a PWM-VSI inverter is more complicated than that of a TCR. Besides, the latter uses a better-established technology than the former.Index Terms-Arc furnace, flicker mitigation, PWM, TCR control, voltage source inverter control. pable@dea.icai.upco.es).Publisher Item Identifier S 0885-8977(00)10314-0.

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2019) 'A simplied algorithm to solve optimal power ows in hybrid VSC-based AC/DC systems.', International journal of electrical power and energy systems, 110 . pp. 781-794.The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractHigh Voltage Direct Current systems based on Voltage Source Converters (VSC-HVDC) are increasingly being considered as a viable technology with advantages, above all when using underground or submarine cables for bulk power transmission. In order to fully understand how VSC-HVDC systems can be best used within existing power systems, it is necessary to adapt conventional tools to carry out system-wide studies including this technology. Along this line, this paper proposes a simplified algorithm to solve optimal power flows (OPFs) in hybrid VSCbased Alternating Current / Direct Current (AC/DC) grids with multi-terminal VSC-HVDC systems. The proposed algorithm makes it possible to seamlessly extend a previous large-scale AC case to which several multi-terminal VSC-HVDC systems must be added. The proposed approach combines two ideas used previously in two different modelling approaches: each VSC is modelled as two generators with a coupling constraint; and DC grids are modelled as notional AC grids, since, in per unit, the equations for the former are a particular case of the latter with resistive lines and no reactive-power injections. In the proposed approach, the hybrid VSC-based AC/DC system is transformed into an equivalent only-AC system. Therefore, the OPF solution of the AC/DC system can be found with the same tool used for the previous AC problem and a simple extension of the original case.Index Terms VSC HVDC, HVDC transmission, multi-terminal, optimal power flow, power systems. NOMENCLATUREA G , A bus , A branch , A slacks : Sets of the generators, buses, branches and slack buses of the AC grids, respectively. A vsc , A dcbus , A dcbranch : Sets of the VSC stations, buses and branches of the multi-terminal VSC-HVDC systems. V i = V i ∠θ i : Voltage at AC bus ī S G,i = P G,i + jQ G,i : Active-(P) and reactive-power (Q) generation (bus i) S D,i = P D,i + jQ D,i : P/Q consumed by the loads (bus i) S i = P i + jQ i : P/Q injections into the AC grid at bus ī Y bus,ik = G ik + jB ik : Admittance matrix of AC line (i, k) I ik : Current through AC branch (i, k) (leaving bus i) (magnitude) S ik = P ac,ik + jQ ac,ik : P and Q flows through AC branch (i, k) (leaving AC bus i) Z ac,ik = R ac,ik + jX ac,ik : Series impedance of AC branch (i, k) B ac,sh,ik : Shunt susceptance of AC branch (i, k) V s,i = V s,i ∠δ s,i ...