Abstract
The article is devoted to the comparative analysis of the effectiveness of the method of generating reactive current during the external voltage drops from the point of view of ensuring the stability of the main electric drives of rolling mills on the basis of three-level frequency converters with active rectifiers. Moreover, the article contains the result of the simulation of parallel operation of the frequency converter with active rectifiers and electric steelmaking complex at overvoltages caused by switching of filter-compensating circuits of the stationary thyristor compensator. These methods are proposed for increasing the stability of the operation of the inverter with active rectifiers when operating in parallel with an electric arc steel-making furnace (EAF) with additional voltage distortions caused by transient processes during switching of the stationary thyristor compensator and filter-compensating circuits. Modern electric drives of rolling mills are usually performed based on powerful synchronous motors and frequency converters consisting of active rectifiers and inverters. Unbalanced voltage drops that occur in the external power supply often lead to break-downs of the main electric drives, which lead to economic losses and defective products. Ensuring stable operation of rolling mills in such modes is an important task. The objects of study are hot rolling mill 1750 of the CJSC "MMK Metalurji". Mathematical models of frequency converters have been developed using by the Matlab-Simulink software for the PWM algorithm with the removal of the selected harmonics and an advanced system for diagnosing of voltage dips. The mathematical models have been used to study the operation of the active rectifier for normal operation mode and during voltage drops. Also on the basis of the mathematical model, the analysis of active rectifier input currents and DC-link voltage has been made. Studies have shown that active rectifier faults can occur by operation of input overcurrent protection or DC-link minimum voltage protection. The comparative analysis results of working of FC-AR with the method of generating reactive current during the external voltage drops has been presented. In addition, the conclusions about influence of regulators parameters in AR control system on stability of working of FC-ARs for voltage drops situations have been made.
Keywords
Active rectifier, frequency converter, pulse-width modulation, algorithms of the PWM, mathematical model, Matlab Simulink, voltage drops, electric drive stability, control system, rolling mill, static var compensator, filter compensating circuit, electric arc furnace.
1. Khramshin T.R., Kornilov G.P., Nikolaev A.A., Khramshin R.R., Krubtsov D.S. Research of Influence of High Power Active Rectifiers on Mains Supply. Vestnik IGJeU [Bulletin of ISPU], 2013, no.1, pp. 80-83. (In Russian)
2. Pupin V.M., Kuftin D.S., Safonov D.O. Analysis of voltage failures in the supply networks of enterprises and methods of protecting electrical equipment. Elektrooborudovanie: ekspluatatsiya i remont. [Electrical equipment: operation and repair], 2011, no. 4, pp. 35-41. (In Russian)
3. Ivanov V.I., ArtsishevskyYa. L. The method of forecasting the statistics of supply voltage failures in the sectional distribution networks of power supply. Izvestiya vysshih uchebnyh zavedenij. Elektromekhanika [Proceedings of Universities. Electromechanics], 2004, no. 6, pp. 18-22. (In Russian)
4. Shpiganovich A.N., Murov I.S. Voltage dips in the electrical systems of enterprises. Natsionalnaya Assotsiatsiya Uchenyh [National Association of Scientists], 2015, no. 2-4 (7), pp. 6-7. (In Russian)
5. Nikolaev A.A., Kornilov G.P., Ivekeev V.S., Lozhkin I.A., Kotyishev V.E. Using of the Static Var Compensator of the Ultra-High Power Electric Arc Furnace for Supporting of Electrical Power System Stability and Increasing Reliability of Factory Power Supply. Mashinostroenie: setevoj elektronnyj nauchnyj zhurnal [Russian Internet Journal of Industrial Engineering], 2014, no.1, pp. 1-11. (In Russian)
6. Nikolaev A.A., Denisevich A.S., Lozhkin I.A., M.M. Investigation of voltage drops influence in the power supply system of the “MMK Metalurji” inworks on the main electric drives of the hot strip mill. Elektrotekhnicheskieye sistemy i kompleksy [Electrotechnical systems and complexes]. Magnitogorsk, Magnitogorsk State Technical University, 2015, no. 3 (28), pp. 8-14. (In Russian)
7. Nikolaev A.A., Denisevich A.S., Bulanov M.V. Investigation of parallel work of rolling mill automated electric drives and an electric arc furnace. Vestnik IGEU [Bulletin of Ivanovo State Power Engineering University], 2017, vol. 3, pp. 59–69. (In Russian)
8. Gasiyarov V.R., Radionov A.A., Maklakov A.S. Simulation of 3L NPC Converter with selective harmonic elimination PWM. Elektrotekhnicheskie sistemy i kompleksy [Electrotechnical Systems and Complexes], 2017, no. 1 (34), pp. 4-9. (In Russian)
9. Maklakov A.S., Radionov A.A., Study of SVPWM with various vector selection tables of three level converter. Elektrotekhnika: setevoy elektronnyi nauchnyi zhurnal [Russian Internet Journal of Electrical Engineering], 2015, vol. 2, no. 1, pp. 30-37. (In Russian)
10. Nikolaev A.A., Denisevich A.S., Ivekeev V.S. Increase in stability of operation of frequency converters with active rectifiers at the commutations of electric equipment of an electric steel-smelting complex. Vestnik Ivanovskogo gosudarstvennogo energeticheskogo universiteta [Bulletin of Ivanovo State Power Engineering University], 2019, no. 5, pp. 48-58. (In Russian)
11. O’Brien K., Teichmann R., Bernet S. Active rectifier for medium voltage drive systems // Applied Power Electronics Conference and Exposition, 2001. APEC. DOI: 10.1109/APEC.2001. 911701.
12. Maklakov A.S. Simulation of the Main Electric Drive of the Mill Rolling Stand. Mashinostroenie: setevoj elektronnyj nauchnyj zhurnal [Russian Internet Journal of Industrial Engineering], 2014, vol. 2, no. 3, pp. 16-25. (In Russian)
13. Khramshin T.R., Krubtsov D.S., Kornilov G.P. Mathematical model of the active rectifier under unbalanced voltage operation conditions. Elektrotekhnika: setevoj elektronnyj nauchnyj zhurnal [Russian Internet Journal of Electrical Engineering], 2014, vol. 1, no. 2, pp. 3-9. (In Russian)
14. Maklakov A.S., Maklakova E.A., Antonova E.V, Demov M.A. Space Vector Modulation algorithm of three-level Converter. Aktualnye voprosy energetiki: materialy Vserossijskoj nauchnoj konferentsii studentov, magistrantov, aspirantov [Topical issues of energy: materials of the all-Russian scientific conference of students, masters, postgraduate students], 2016, pp. 100-106. (In Russian)
15. Nikolaev A.A., Anokhin V.V., Urmanova F.F. Developing of new method of switching over voltage reduction in harmonic filters of static var compensator. Elektrotekhnika: setevoy elektronnyi nauchnyi zhurnal [Russian Internet Journal of Electrical Engineering], 2015, vol.2, no. 4, pp. 72-76. (In Russian)
16. Nikolaev A.A., Kornilov G.P., Denisevich A.S. Developing of a new calculation method for harmonic filters parameters of arc furnace static var compensator. Vestnik YuUrGU. Seriya «Energetika» [Bullen of the South Ural State University. Power Engineering series], 2018, vol. 18, no. 4, pp. 89-100. (In Russian)
17. GOST 32144-2013. Electric energy. Electromagnetic compatibility of technical equipment. Power quality limits in the public power supply systems. Moscow, Standartinforn Publ., 2014. 20 p. (In Russian)
18. AzeddineDraon, Senior Mieee A space vector modulation based three-level PWM Rectifier under Simple Sliding Mode Control Strateg. Energy and power Engineering, 2013, no. 5, pp. 28-35.
19. Farhan Beg Space Vector Pulse Width Modulation Technique Based Design and Simulation of a Three-Phase Voltage Source Converter System. World Academy of Science, Engineering and Technology, 2014, no. 9, pp. 1304-1307.