PROJECT TITLE :

System Design of Adjustable Speed Drives, Part 2: System Simulation and ac Line Interactions

ABSTRACT :

Part one of “System Design of Adjustable Speed Drives” [one] investigated the second-order effects that occur as interactions between adjustable speed drives (ASDs) and system-connected equipment, specifically regarding commonmode (CM) voltage and ground noise current injected within the system and differential-mode (DM) voltage spikes on the load because of ASD semiconductor switching [1]. This article (Part 2) continues the investigation by proposing high-frequency ASDs, cable, and motor models employed in system simulation to spot and mitigate the advanced DM or CM injected. Theoretical element models were bridged with field experience to simulate and resolve a sensible low-voltage (LV) field example of parallel high horsepower inverters having instantaneous overcurrent (IOC) trip problems thanks to circulating CM currents between inverters and ground. Part models also are used in a system electromagnetic interference (EMI) simulation example of an influence structure, that induced line-to-ground noise current in an industrial plant ground grid.