Evaluating the Potential for Increasing the Efficiency of Using STCs for Voltage Balancing in the Case of the Skovorodino NPS-21 Oil-Pumping Station

Abstract

Outages of three-phase motors owing to voltage asymmetries produced by the operation of distant distorted loads are examined. Several ways of solving this problem are examined, including with a phase-controlled static thyristor compensator (STC). A method is proposed for choosing the power of the STC needed for guaranteed compensation of the reverse (negative) sequence voltage taking into account the permissible operating time for three-phase motors with a given reverse sequence voltage level. Algorithms for phase control of STC are proposed and their efficiencies are compared on a test-bed. It is shown that the use of a special algorithm with priority suppression of the negative sequence voltage makes it possible to enhance the efficiency with which the installed STC power is used and to reduce the number of outages of motors caused by protections that are sensitive to the negative sequence voltage.