Electric arc furnace power quality improvement by applying a new digital and predicted-based TSC control

Static VAR compensators (SVC) can improve some of the power quality (PQ) indices such as voltage flicker, unbalances, and power factors in power systems if properly controlled. Different nonlinear and time-varying loads generate these parameters. One of the great nonlinear loads is the electric arc furnace (EAF), which causes waveform distortions, voltage unbalances, and fluctuations. In this paper, a new digital and prediction-based control for thyristor switched capacitors (TSCs) was proposed to compensate an actual steel industrial plant. The digital control was based on generating adequate synchronous pulses, calculating required suitable susceptance, and measuring correct reactive power. The proposed TSC improved the PQ by means of the feedback from voltage and power factor. A predictive method based on time series and recursive least square with dynamic learning factor was then applied to estimate EAF reactive power in the future so that the TSC performance was enhanced by reducing the natural time delay. A band-pass harmonic filter was designed to compensate the load current harmonics and to protect the capacitor banks in the TSC. Finally, the suggested TSC was implemented in a steel industrial plant as an actual power system with 2 EAFs. The modeling and experimental results indicate the effectiveness of the proposed TSC.

PDF

___

[1] Alonso MAP, Donsion MP. An improved time domain arc furnace model for harmonic analysis. IEEE T Power Deliver 2004; 19: 367-373.
[2] Mousavi Agah SM, Hosseinian SH, Askarian Abyaneh H, Moaddabi N. Parameter identification of arc furnace based on stochastic nature of arc length using two-step optimization technique. IEEE T Power Deliver 2010; 25: 2859-2867.
[3] Gol M, Salor O, AlboyacıB, Mutluer B, C¸ adırcıI, Ermi M. A new field-data-based EAF model for power quality studies. IEEE T Ind Appl 2010; 46: 1230-1242.
[4] Beites LF, Mayordomo JG, Hernandez A, Asensi R, Harmonics, inter harmonic, unbalances of arc furnaces: a new frequency domain approach. IEEE T Power Deliver 2001; 16: 661-668.
[5] Torabian Esfahani M, Vahidi B. A new stochastic model of electric arc furnace based on hidden Markov model: a study of its effects on the power system. IEEE T Power Deliver 2012; 27: 1893-1901.
[6] Parniani M, Mokhtari H, Hejri M. Effects of dynamic reactive compensation in arc furnace operation characteristics and its economic benefits. In: Transmission and Distribution Conference and Exhibition Conference; 610 October 2002. pp. 1044-1049.
[7] Depormmier B, Stanley J. Static var compensator upgrade in a steel mill. In: Power Engineering Society General Meeting; 1317 July 2003; Toronto, Canada. pp. 362-365.
[8] Sheng X, Jian-Feng Z, Guo-Qing T. A new SVC control strategy for voltage flicker mitigation and integrated compensation to electric arc furnace. In: Third International Conference on Electric Utility Deregulation and Restructuring and Power Technologies; 69 April 2008; Nanjing, China. pp. 1972-1976.
[9] Wang YF, Jiang JG, Ge LS, Yang XJ. Mitigation of electric arc furnace voltage flicker using static synchronous compensator. In: 5th International Power Electronics and Motion Control Conference; 1416 August 2006; Shanghai, China. pp. 1-5.
[10] Garcia-Cerrada A, Garcia-Gonzalez P, Collantes R, Gomez T, Anzola J. Comparison of thyristor-controlled reactors and voltage-source inverters for compensation of flicker caused by arc furnaces. IEEE T Power Deliver 2000; 15: 1225-1231.
[11] Chow TW. Measurement and evaluation of instantaneous reactive power using neural networks. IEEE T Power Deliver 1994; 9: 1253-1260.
[12] Yoon WK, Devaney MJ. Reactive power measurement using the wavelet transform. IEEE T Instrum Meas 2000; 49: 246-252.
[13] Gomez-Martinez MA, Medina A, Fuerte-Esquivel CR. AC arc furnace stability analysis based on bifurcation theory. IEE Proc-C 2006; 153: 463-468.
[14] Andrade MT. A new current relay for capacitors in medium voltage LC harmonic filters. In: Transmission and Distribution Conference and Exposition; 811 November 2004. pp. 686-690.
[15] Mattavelli P. Design aspects of harmonic filters for high-power AC/DC converters. In: Power Engineering Society Summer Meeting; 1620 July 2000; Seattle, WA, USA. pp. 795-799.
[16] Samet H, Golshan MEH. Employing stochastic models for prediction of arc furnace reactive power to improve compensator performance. IET Gener Transm Dis 2008; 2: 505-515.
[17] Fregosi D, White LW, Green E, Bhattacharya S, Watterson J. Digital flickermeter design and implementation based on IEC Standard. In: Energy Conversion Congress and Exposition; 1216 September 2010; Atlanta, GA, USA. pp. 4521-4526.