Adaptive control of reversible thyristor electric drives in brewing lines based on integral stability criterion

The study presents a methodology for adaptive control of reversible thyristor electric drives in brewing lines. An integral-stability criterion is proposed, which simultaneously minimizes thermal losses and maintains the required system stability margin. Based on a posteriori analysis of the motor current signature, an adaptive PID controller was developed and implemented using an implicit difference scheme with a variable step. Simulation and full-scale tests confirmed a reduction in energy consumption by 9-10%, a decrease commutator temperature, and a more than fourfold reduction in unscheduled downtimes.

Aim. The study is to develop a control method for reversible electric drives that ensures both improved energy efficiency and operational reliability under high-frequency reversals and power supply fluctuations.

Methods. The proposed approach relies on an integral functional combining thermal loss minimization with stability assessment via the Lyapunov function. Controller parameters were adjusted using statistical characteristics of the motor current signature. The numerical implementation uses an implicit difference scheme involing an adaptive discretization algorithm. The effectiveness of the method was confirmed through simulation modeling and experimental testing on brewing equipment.

Results. The experiments demonstrate reducing specific energy consumption by 8-10%, reducing thermal stress and peak currents, and improving stability margin to at least 25%. The commutator temperature is reduced by 11-13 °C, extending insulation lifetime. The number of unscheduled shutdowns decreases more than fourfold compared with conventional PI control.

Conclusions. The integral-stability criterion has proven its effectiveness, enhancing simultaneously energy efficiency and reliability of electric drives. The developed controller is compatible with industrial PLCs and SCADA systems, which facilitates implementation. Economic evaluation confirmes the feasibility of the approach, with a payback period of less than 1.5 years, making the method promising for widespread application in brewing and related industries. The economic evaluation confirms the feasibility of this method, with a payback period of less than 1.5 years, which makes the approach promising for large-scale application in the brewing and related industries.