Real-Time Controller HIL Simulations for Motor Starting Studies

In this paper a virtual plant is combined with the hardware controllers of a reduced voltage soft-starter and adjustable frequency motor drive to simulate motor starting interactions. During across the line motor starts, as well as reduced voltage starting, a sag condition typically occurs as the shaft comes up to full speed. In industrial power systems adjacent loads such as adjustable frequency motor drives may be impacted by this transient disturbance. The situation can be further aggravated when the common bus is fed from a back-up diesel-generator set. Using a real-time controller hardware-in-the-loop simulator this starting condition will be examined. The goal is to determine if the power flow remains in the safe operating area of the diesel-generator set and capture how the adjustable frequency drive's hardware controller reacts to the disturbance. Multiple starting scenarios are examined including reduced voltage primary reactor starting, reduced voltage solid-state soft-starter starting, and the number of parallel generators to determine how the adjustable frequency drive already operating a motor responds.