In this article the possibility of methane gas extraction in coal deposits exploitation is considered. Experimental data on the application of hydrodynamic impact on a gas-saturated outburst coal seam prior to its baring in order to reduce gasdynamic activity due to an intensification of methane emission are presented. Also a structural and technological scheme of degassing pipelines that includes emergency protection and monitoring of coal mine methane parameters in real-time mode to ensure a safe, trouble-free process of its transportation to the cogeneration plant for further utilization is proposed.

The physics of hydrodynamic impact (HDI) is in the softening of the coal seam due to the generation of alternation stress in it. Stress is carried out due to injection and discharge of fluid into the coal seam in the filtration mode. The mathematical model of the processes occurring in the coal massif under HDI was developed. The model allows to determine the nature of the coal destruction in forward and inverse filtering of fluid in the massif. Cracking in the process of fluid filtration is achieved while simultaneously fulfilling two criteria: power and energy.

Purpose. To increase the energy efficiency of the electromechanical system of production and distribution of com pressed air by applying a new way of controlling the electric drive of the compressor plant. methodology. The following methods are used: method of parametric optimization (scanning)-to solve the problem of conditional optimization of the duration of the compressor state on each control cycle, with different charges of compressed air Q; method of approximation of the initial data of the electromechanical system; regression analysis-when constructing a nonlinear dependence of compressor performance and loss of compressed air. findings. The reasons of low energy efficiency of electromechanical system for production and distribution of pressurized air, based on the reciprocating compressor, were considered. Correlation and mutual influence of sepa rate system's elements and their modes of operation were analyzed. The analysis of energy dissipation levels in the elements of electromechanical system was carried out to improve the method for controlling the electrical drive of compressor by applying new engineering solutions. Analytical dependences of the efficiency factor on energy dissipa tion levels in certain elements of the system and its duty parameters with twostep action of compressor output were established. A mathematical model for calculation of the coefficient of efficiency of the electromechanical system was carried out; the optimization problem for the operation parameters was formulated and solved, with certain assump tions and limitations, upon condition of twostep action of the electrical drive of the compressor. The proposed model is distinguished from existing models by the possibility of operation regimes accounting for all elements of the electromechanical system to determine its energy indicator-the coefficient of efficiency. The results of parametric optimization of operational regimes of the electromechanical system for production and distribution of pressurized air, with different levels of pressurized air consumption, were proposed. originality. It is proved that with an increase in the performance of air compressors with the proposed method of control, the efficiency of the system increases in comparison with the traditional method for controlling compressors, which increases the energy efficiency of the electromechanical system as a whole. Practical value. The algorithm of control of compressor power consumption, which reproduces the principle of determining the costs of compressed air on the basis of measuring the speed of pressure change in its receiver, is de veloped, and it allows predicting the duration of the control cycle.

Purpose. Establishing the regularities of changes in influence of power quality indicators caused by the operating modes of photovoltaic (PV) station inverters on the operating modes of distribution networks’ equipment to improve their energy efficiency by reducing power losses. Methodology. To solve the scientific problems, the following methods are used such as: the method of harmonic analysis (Fourier integral); decomposition of the current spectrum by amplitude-frequency component using Mdaq-14 hardware and software platforms and LabVIEW software; the method of data correlation analysis to determine the higher harmonic current dependence on the load of an on-grid inverter; mathematical and physical modeling in the development of a way to improve the energy efficiency of on-grid inverters of PV stations. Findings. The conducted studies on electromagnetic compatibility indicators of grid photovoltaic station inverters in stationary and dynamic operation modes made it possible to establish the characteristic regularities of changes in the spectrum and amplitudes of higher harmonic components depending on the level of inverter loading. Hyperbolic dependences of the change in the sinusoidal signal distortion coefficients of the harmonic component on the level of inverter loading were experimentally established. A method has been developed for reducing the electromagnetic interference levels caused by photovoltaic station converters by implementing a circuit solution and algorithm for loading on-grid inverters in non-stationary modes in order to improve their electromagnetic compatibility and increase the energy efficiency of distribution networks with appropriate decentralized sources. Originality. The regularities are established of influence of the operating mode’s parameters of photovoltaic station inverters on the indicators of electromagnetic compatibility in their power supply system, including taking into account special circuit solutions, which allows increasing the energy efficiency of distribution network modes. Practical value. The method for reducing the electromagnetic interference levels generated by photovoltaic station inverters by implementing the proposed circuit solution and algorithm for loading the on-grid inverters in non-stationary modes is universal and can be applied to any photovoltaic station. This will help to reduce the power losses and electromagnetic damage to equipment from the action of higher harmonic components. Granting the established regularities of higher harmonics influence will allow one to take into account the impact of the relevant indicators on the additional insulation heating of power supply system elements and to assess the corresponding electromagnetic damage, to provide recommendations for consideration of the modes in calculating methods and PV equipment selection.

MACHINE-TRANSFORMER UNITS FOR WIND TURBINES Background. Electric generators of wind turbines must meet the following requirements: they must be multi-pole; to have a minimum size and weight; to be non-contact, but controlled; to ensure the maximum possible output voltage when working on the power supply system. Multipole and contactless are relatively simply realized in the synchronous generator with permanent magnet excitation and synchronous inductor generator with electromagnetic excitation; moreover the first one has a disadvantage that there is no possibility to control the output voltage, and the second one has a low magnetic leakage coefficient with the appropriate consequences. Purpose. To compare machine dimensions and weight of the transformer unit with induction generators and is an opportunity to prove their application for systems with low RMS-growth rotation. Methodology. A new design of the electric inductor machine called in technical literature as machine-transformer unit (MTU) is presented. A ratio for estimated capacity determination of such units is obtained. Results. In a specific example it is shown that estimated power of MTU may exceed the same one for traditional synchronous machines at the same dimensions. The MTU design allows placement of stator coil at some distance from the rotating parts of the machine, namely, in a closed container filled with insulating liquid. This will increase capacity by means of more efficient cooling of coil, as well as to increase the output voltage of the MTU as a generator to a level of 35 kV or more. The recommendations on the certain parameters selection of the MTU stator winding are presented. The formulas for copper cost calculating on the MTU field winding and synchronous salient-pole generator are developed. In a specific example it is shown that such costs in synchronous generator exceed 2.5 times the similar ones in the MTU. References 3, figures 2.