Conceptual Area of Development of Power Saving Thyristor Electric Drives of Rolling Mills

Thyristor electric drives of the rolling mills are known to be the most power-intensive consumers at the iron and steel works. Obviously, significant losses of electric power are connected with consumption of reactive power that depends on the value of the reserve of rectified EDV of the thyristor converter. The paper mentions characteristic dynamic modes providing a maximum reserve of the rectified EDV. It estimates the influence of the rectified EDV on the value of reserve for overcorrection in the impact-loading mode. Experiments have proven the impact of the network voltage deviation in amount of 10–12% decreasingly. The reserve of the rectified EDV has been divided into components. The paper provides a defined concept for generation of the power-saving systems of two-region speed control based on the principles of rearranging the reserve of the rectified EDV in the steady state and dynamic modes. It considers the method and system of two-region dependent speed control as a function of the rectified EDV of the thyristor converter. The system is proved to provide a constant reserve of the rectified EDV of the thyristor converter within the load range of the electric drive that is lower than the rated one. It is reasonable to develop the system of two-region speed control providing power saving due to reduction of the rectified EDV reserve in all dynamic modes during rolling cycle.