Abstract
Relevance of the task. Quality of electrical energy is a vital prerequisite for operation of compact metallurgical plants consisting of melting complexes based on electric-arc furnaces and static var compensators that work together with rolling mills consisting of flat steel and section mills as well as continuous machining of the strip. Quality parameters of electrical energy, in turn, depend upon a number of characteristics that influence operation of essential consumers at such plants. One of the most significant quality characteristics is voltage fall in the external supply network. It negatively affects plants overall. For today, there is little research among domestic and foreign researchers that deal with reasons of voltage fall in regional power networks. Also, there is no research that would deal with measures for maintaining voltage at a desired level even during designing inner electrical supply. Existing methods of damping voltage fall are based on purchasing new equipment which reacts to changing voltage in the distribution network and restores normal operation mode by switching to a standby power supply. Such a method is unfavorable economically as equipment is expensive, and not every plant is ready to buy it. As such, the task to do is development of a new method of designing electrical power supply systems for workshops. Such method would be based on in-house reserves of reactive power accumulated in static compensators for dumping voltage falls. Goal of the job: analyzing voltage fall in regional electrical networks which are caused by external factors and working out recommendations on designing electrical power systems for small metallurgical plants which don't require significant investments for purchasing additional equipment. Methods used: the basic information for the research is datasets on voltage falls at existing metallurgical plant MMK Metalurji Ltd., Iskanderun, Turkey, and information on weather conditions within the researched power districts. Experimental data has been statically processed by Microsoft Office Excel. Originality: the research findings are new as there has been a research on how voltage falls depend on lightning discharges. Based on this research, a new method of designing in-shop electrical power systems has been developed which defends the electrical power systems from voltage fall in the outer power system. Findings: by the example of MMK Metalurji Ltd. we can see principles of occurring voltage falls depending on weather conditions in various seasons; also, measures of improvement of in-shop power systems have been developed with the aim of making them more reliable. Practical relevance. The results obtained are highly significant for existing small metallurgical plants consisting of electric furnace and rolling steelmaking. Also, the results can be used at designing of new metallurgical plants.
Keywords
Reliability of power supply, voltage dips, lightning discharges, frequency converter, hot rolling mill, electric drive of the rolling stand, electric arc furnace, static var compensator.
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