The electric vehicles development has a high potential for energy saving: an energy-saving traffic control can reduce energy resource consumption, and integration with the power grid provides the ability of daily load pattern adjustment. These features are also relevant for underground mining. The critical element of vehicle-to-grid integration is the charging infrastructure, where wireless charging is promising to develop. The implementation of such systems in underground mining is associated with energy efficiency issues and explosion safety. The article discusses the development and research of a wireless charging system for mining electric locomotive A-5.5-600-U5. The analytic hierarchy process is used for justification of the circuitry and design solution by a comparison of different technical solutions based on energy efficiency and safety criteria. A complex computer model of the wireless charging system has been developed that gives the transients in the electrical circuit of a wireless charging system and the high-frequency field density distribution near the transmitting and receiving coils in a 3D setting. An approach to ignition risk evaluation based on the analysis of high-frequency field density in the charging area between the coils of the wireless charging system is proposed. The approach using a complex computer model is applied to the developed system. The study showed that the wireless charging system for mining electric locomotives operating in the gaseous-and-dusty mine is technically feasible and there are designs in which it is explosion safe.
The article discusses an approach based on the analysis of the drive motor currents to create an additional means of protection against emergency situations during the operation of bridge cranes associated with lifting a load with a mass exceeding the permissible one . A mathematical model of an overhead crane drive is described, as well as the results of computer simulation. It is shown that in the process of lifting up, before the stage of lifting the load, the stator current of the drive electric motor does not depend of the load mass, but when the load is detached, already for several periods of the mains voltage after the rope is pulled, when the mass of the load is exceeded, a measurable excess of the amplitude value of the current is recorded. This pattern has been confirmed for a number of cranes of various lifting capacities used at metallurgical enterprises. The possibility of diagnosing excess weight of the lifted load with a higher speed than existing mechanical methods of overload control is demonstrated, at the same time it is not required to make changes to the structural elements of overhead cranes.
Restructuring of the energy sector and liberalization of the electricity market resulted in separation of a single industry into a multitude of generating companies, federal and interregional distribution utilities, regional power providers and energy suppliers. For a number of reasons, related to the process of managing separate companies, faults in the laws and regulations, and unsatisfactory technical state of the energy equipment both on the part of distributors and consumers, reliability of energy supply faces increasing negative trends, which potentially can lead to big problems. Up to this day the energy sector does not have a developed database on the state of equipment and results of its maintenance, nor has it defined criteria to actually assess technical conditions of the equipment. The authors propose to develop and implement a mechanism aimed at technical auditing and monitoring of the engineering state of external power supply system, whose results can help in the development of more efficient and economically sound measures to improve reliability of energy supply. In recent years, a lot of attention has been paid to the issues of enhanced security of industrial power supply. However, specific characteristics of underground coal mining and enormous work load of the production process limit the applicability of developed methods and algorithms. Existing research does not address economic issues of reliable energy supply, either direct (economic damage from power interruptions, contractual security of supply, tariff regulation) or indirect (charges for utility connection with a required level of reliability). There is no explicit definition for the term «autonomous energy source», nor is there a list of power receivers falling into the first and «special» categories according to their reliability. The paper contains a range of urgent problems and solutions that will increase reliability of external power supply in the coal mines.
