Shestopalov S. Automatic control of grain transferring processes on elevators: optimization of TTL loading with limitations of «emergency situation» type

The new concepts and specific solutions to the problem of thread transport lines (TTL) grain loading automatic control are presented. The problem is exa-mined as conditional optimization problem with limitations of «emergency situation» (ES) type with guaranteed prevention of the emergency protection trips operation in the real time. TTL loading control, when ES is caused by a grain obstruction in the boot drum of its paternoster (ES1), is implemented by automatic control system (ACS) with a switching structure, which includes two control loops. The loading control in the main loop is fulfilled by changing the opening level of the silo gate valve, in the auxiliary loop – by the speed control of the conveyor belt under the silo. Switching from the main circuit to the auxiliary occurs when ES1 is detected, which is created either purposefully – by the optimization search algorithm or spontaneously – due to the disturbances action. After ES1 elimination, in order to return from the auxiliary control loop to the main one, drive electric motor (DEM) feed frequency control loop is implemented at the nominal value by the gate valve under the silo. To improve the quality of control, it has been proposed to convert the main loop of the ACS to a cascade structure. Controlling the loading of the TTL, when the ES is caused by overheating of the DEM of its conveyors (ES2), is implemented by stabilizing at the permis-sible level of the thermal state of the most overheated DEM. In the ACS with a switching structure, this stabilization is provided by introducing an external feedback loop with the thermal state controller in relation to this ACS. In the extreme situation, when the DEM thermal state stabilization is impossible, preemptive start of the technological shutdown algorithm prevents an emergency stop. Based on the ACS with a switching structure, automated loading optimization system (ALOS) for TTL of grain transferring on elevator in the Hmelnik city was developed. Its control algorithms have been debugged and tested on the simulation model, and application software – on the software-hardware complex (SHC), which implements the technology of semi-industrial trials. ALOS was put into operation, its comprehensive production trials were carried out, the results of which confirmed the effectiveness of scientific and technical solutions developed in the thesis.