Development of power factor dynamic compensation unit of electric motors used in the composition of the electric drives of the sprinking machine sections

Electrified irrigation machines have an automatic control system with in-line synchronization devices. System operation leads to frequent starts of electric motors. The movement of the machine is set by the cycle of repeating the switching on of the extreme electric drive in the range of 100 seconds, in the interval of which 5-11 starts of all electric drives are observed. More-over, the operating time of some electric drives is 2-5 seconds. During a 12-hour (day) watering period, the number of starts reaches 4000 times. This procedure for the automatic control system leads to an overestimated power consumption and a negative impact on the energy source. The starting mode of the electric drives of the sprinkler sections is characterized by a short duration and unstable consumption of reactive power. Therefore, the aim of the work is not only to develop a device for dynamic compensation of reactive power, but also to experimentally test its operability, as well as to determine the optimal parameters of the device and the possible effect of its application. The calculated capacity for the starting mode can lead not only to compensation, but also to overcompensation of reactive power. Therefore, the experiment was set up with varying the capacitance of the capacitor bank and the duration of switching on the device for dynamic compensation of reactive power. Based on the experimental data, the dependence of the share of reducing electricity consumption on the capacity of the capacitor bank and the duration of its switching on is described by a second-order polynomial, which adequately characterizes the experimental studies within 7% discrepancy between the calculated and experimental data. The greatest effect of reducing electricity consumption for a sprinkler consisting of 10 sections, with the number of starts 5-7 times in a 100-second cycle of operation of the extreme electric drive, for 12 hours of operation of the power factor dynamic compensation unit allows reducing electricity consumption by 12,1-6,2%.