Increase of energy resources efficiency, in particular of power energy, is one of the factors facilitating stability and sustainable development in all branches of industry. One of the most power-consuming spheres of industry is mining industry, which is characterized by outrunning growth of energy consumption relating to rates of industrial production growth.

A modern mining enterprise represents a complicated process system providing mining, transportation and shipment of coal to consumers. In this respect to reach maximum index numbers as regards to enterprise efficiency they increase capacity of mining equipment drive, that in its turn causes increase of expenditure for power energy. Power consumption growth in mining industry is caused not only by absolute production growth, but also by qualitative changes of technique, complication of mining-and-geological conditions of coal mining, implementation of environment protection measures. As of today rise of power energy cost enforces different enterprises, mines as well, to use power resources more economically and reasonably. For this purpose different automated power control and metering systems (APCS – Automatic Process Control System “Power supply”) are introduced at mines. These systems are designed for control and metering of power consumption by process plants as well as for issue of “advices” for disconnection of power-consuming plants with the purpose of avoiding excess power consumption by the mine. However, according to Safety norms in coal mines, Maintenance rules for electrical installations, not all the plants are allowed to be shut down. That is why power energy excess consumption with implementation of the specified APCS exists. The work proposes together with use of “Power supply” APCS to apply operational dispatch management system, which in real-time mode, in case if power energy excess consumption occurs, provides transfer of operation of power-consuming process plants into power-saving mode without interfering operating procedures.

Industrial power consumption share of coal enterprises of Ukraine in some regions amounts to 60-65%. Nowadays because of multiple power energy appreciation its share in production prime cost has grown sharply, and makes 18-22%. Thereby, for efficient operation of power-consuming coal enterprise along with process plants efficiency increase it is required to reduce power consumption both by certain plants, and by the enterprise in general. Power consumption reduction, including, also in the period of maximum loading on power energy system, can be achieved either by disconnection of plants, or by change of their operation mode. However, in accordance with Safety rules in coal mines not all the plants are allowed to be shut down. The existing “Power supply” APCS just registers power energy consumption by plants and by the enterprise as a whole. That is why development of automated operational dispatch management system, which in real-time mode controls power energy consumption and in case of excess consumption provides transfer of operation mode of power-consuming process plants to power-saving mode is a topical issue.

Objective of the work is increase of coal enterprise operation efficiency by means of reduction of energy demands as a result of justification of control parameters and power consumption method, along with using of automated operational dispatch management system.

A scientific task consists in establishing of principles of power-saving modes for process plants to define control parameters, methods and algorithms of their operation modes’ change, which is the basis for development of mine automated operational dispatch management system.

To reach the set objective it is necessary to execute the following research tasks:

• justification of parameters and methods of process plants load control in mine;
• development of mathematical models of operation modes for power-consuming process plants and their examination by computers with the purpose of working out the methods of transfer of plants’ operation into power-saving mode;
• development of automation technologies and structure of automated operational dispatch management system ensuring reduction of coal enterprise power consumption.

The load on electric drive of process plants determines power consumed by these plants. There are different ways of load determination on electric motor shaft: moment measurement, current intensity measurement, measurement of active power consumed by electrical motor. I this work it is proposed to measure active power in order to determine load on electric drive.

For power consumers of mines located on the surface of the enterprise there are different load sensors and power consumption meters. However, for underground power consumers at present time there are no available commercially produced power consumption control devices. Fig. 1 shows a vector diagram of currents and voltages in the controlled mine three-phase network with insulated neutral.

As can be seen on the diagram, with multiplication of signals corresponding to voltage and one of vectors, or with pure active load of network, there is a phase angle between these vectors. Analysis of vector diagram shows that if current vector is deducted, the result is a vector equal by module, and phase angle between this vector and voltage vector with pure active load is equal to zero. That is why measurements of instantaneous value of three-phase active power can be made as. At that this method of three-phase power transformation is applicable with asymmetry of three-phase power up to 2%.

The most power-consuming plants at a mine are main pumping system, main belt conveyor, main fan system of main ventilation. These plants belong to so-called consumers-regulators. Therefore, to reduce excess power consumption of mine it is necessary to change operation mode of mother conveyor lines, main fan systems and main water-drainage installations.

Two ways of regulation of conveyor system operation mode are possible: continuous and discrete [2].

It is proposed in this work to use discrete regulation of belt linear speed, which allows reducing power consumption by 5-21% in comparison with uncontrolled drive. In this connection it is necessary to use belt linear speed regulator, which while switching of conveyor system operation from one speed to another ensures such change of drive motor rotation rate, when dangerous dynamic loads on the belt are non-available, and this increases reliability of conveying unit.

At mine enterprise in power system load control mode it is reasonable to organize operation of water-drainage pumping facilities, characterized by free cyclic work schedule in time and great power consumption.

Depending on principle of creation of conditions ensuring offpick power consumption by drainage it is conditionally possible to distinguish the following two methods of automatic control: automatic pre-pick switching-in and automatic control with excess hydraulic power available [5].

In this work for change of main water-drainage installation operation mode in the period of maximal load on power system there was adopted a method of positive locking with feeding movement step control, as it is characterized by high precision and reliability of drainage operation organization and it is recommended for high power drainage plants control.

According to Safety rules in coal mines the main fan systems may not be shut down, it is only allowed to regulate them

Depending on fan type there are two methods of plant operation mode regulation:

• regulation of turning vanes guiding device (centrifugal fans) or the rotation of the impeller blades (axial fan);
• regulate the fan speed by changing the frequency of rotation of the drive motor [7].

From the point of view of regulation efficiency the second method is more preferable. That is why regulation of fan installation operation mode with the help of wound-rotor slip recovery system (WSRS) is adopted in this work.

At present time there are different computer-aided operational dispatch management systems for coal mines. One of such systems is a system manufactured by “INGORTEKH” LTD [10].

Also well-known is a unified telecommunication computer-aided system of dispatch control and management UTCS worked out by “Petrovskyy machine building plant” SE [11].

Having analyzed functional capabilities of existing automated operational dispatch management systems the work led to the conclusion that these systems do not ensure operation of the enterprise in power-saving mode.

Information on current power consumption of power-intensive process plants is required for operative management of power consumption of the coal mine.

Active power measuring unit (APMU) is worked out in the work, which enables:

• linear vector transformation of voltage measuring transformer signals U_АС and current transformers I_А and I_С integrated into high-voltage factory-assembled switch-gear KRUV-6 into instantaneous value of three-phase active power;
• delivery of signals about active power consumed by electrical motor, commuted by high-voltage factory-assembled switch-gear KRUV-6, and about power energy consumption at “Power supply” APCS.

For measuring of belt conveyor operation mode it is proposed to use subsystem of automatic power consumption regulation of belt conveyor included into the structure of automated operational dispatch management system of the mine.

Fig. 2 shows a block scheme of automatic regulation subsystem for power consumed by belt conveyor.

The following symbols are applied in the fig. 2: Computer – an industrial computer, included to the structure of “Power supply” APCS, which executes centralized control over power energy consumption for power-intensive operating procedures, and forms necessary “advices” for change of plants’ operation mode, including conveyor ones, to reduce power energy consumption, if it is possible technologically and does not violate safety requirements. KROK device is a technology package for automated control of cutter-loader operation, which is designed for identification of miner combine operation mode: whether it is switched on or off, operates on load or in idle mode, registers combine location in a face [9]. UKRK is a microprocessor unit of conveyor operation mode adjustment, interacting with Computer (computing unit), KROK device and automated conveyor plant and forms set points for conveyor belt speed control unit. Automated conveyor unit is a conveyor unit equipped with automation apparatus. To control conveyor units it is necessary to apply computer-integrated automation systems, which are capable of conveyor transport operation coordination by means of computer units and allow for expansion, if necessary, of technical facilities structure, in particular in our case, of automatic belt speed control units use. ACS system is an agreed system of conveyor drive motor rotation rate.

So, when computer unit delivers a command about necessity of belt speed regulation – transfer into power-saving mode – UKRK device defines coal charge of the belt in accordance with combine operation mode and forms the necessary economically profitable set point by speed in ACS. Automatic Control System transfers drive motor rotation rate to the set belt speed without dangerous dynamic loads on the belt.

Further it is planned to work out subsystem of main water-drainage installation control, also in hours of maximum load on power system, development of mathematical models of operation modes for power-consuming process plants, modeling of different modes of operation for mine process plants.

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