ABSTRACT
Drive system used for mine lifting plant (MLP) must correspond to mechanism demands, among that the some of general demands are providing the maximum speed for transporting the people - 12 m/s; and maximum allowable speed of lifting vessel approach to extreme position for people and load - 1.5 m/s.
Nowadays, the system thyristor converter – motor (TCM) is the most widespread and it meets the general requirements from the lifting plant. As a result of jump in electricity charges, the work efficiency of the system on direct current is considerably reduced, that is why nowadays tendency is change for energy-saving systems of alternate current, where it is necessary to note the frequency converter - asynchronous motor (FC-AM) and frequency converter -synchronous motor (FC-SM). The use experience of the system FC-SM by Swedish firm ABB during the lifting in Pihsalmy (Finland) have shown the high drive efficiency, formation of desired movement tachogramma with speedup and hitch limit on pickup stage, on slowing down, and possibility to work with maintenance cos
=1, control system capacity for minimization the effect of higher harmonics. As the general default we can note the high value of power equipment and converters.
Image 1 – Functional scheme of control system of synchronous drive with ac electronic motor
There is no simple decision for choosing MLP drive system, therefore it is necessary to examine each case individually for particular mechanism. The choice of MLP drive system is made by the next criteria: the needed power and starting moment, the control degree according to process requirements, the value of equipment.
The using of ac drive with frequency converters can be rational in the next situations:
1. the power of mine switching substation is not very high and it does not allow the starting loads from direct current TC;
2. at the starting of TCM drive of the lifts, the reactive powers found inadmissible voltage raise and voltage fluctuation;
3. the lift drives are removed from electric and distribution substation, the electrical lines have the wide length and resistance, when using of TCM system could cause inadmissible voltage raise and fluctuation according to all-Union State Standard;
4. a great quantity of drives is connected to the electric substation, that worsen the harmonic structure of the electric network voltage till inadmissible degree.
The direct current drive is the least capital-intensive for gearless drive of high powers on the territory of CIS, even taking in account the value for additional equipment for electric network protection. But if considering the world tendencies of science development and prices reduction of high-accuracy equipment, the using of ac current would be prevailing in our country. So, have compared the MLP and FC-SM systems by realization of process requirements, we proposed to use the FC-SM system as the general one on the mine «Krasnolimanskaya».
The dynamic investigations of electrical mechanical system of MLP with FC-SM drive have been carried out in the MatLab sphere (application Simulink) and have shown the possibility to realize the desired movement tachogramma on pickup, slowing down and braking stages.
Image 2 - Model of system of the subordinated regulation of speed without and with setting mechanism intensity.
Image 3 - Lifting of load by trapezoidal diagramme and descent (1 - P - regulator, 2 - PI - regulator, 3 - IF - regulator)
References list
1. Electromechanical systems of the transport mechanisms/ under the editorship of the professor Borisenko, DonNTU, MIDIEL, VEBER, 2007 - p.349
2. Electric drive theory Part 1:teaching aid/A.B. Zelenov.- Alchevsk:DonSTU, 2005.- p.394
3. Electromechanical operations in the ac motors.- L.: Energy. Leningrad dept., 1980.- p344.
