Mitigation of Motor Starting Voltage Sags Using Distribution-Class STATCOM

The addition of four 7000 HP, 13.2 kV induction motors by an offshore oil production and drilling company to its existing fleet of four 6000 HP motors resulted in power quality concerns for other utility customers served from the 115-kV transmission system. While new transmission upgrades planned in the area are expected to provide additional short-circuit capacity, detailed motor starting studies indicated the need for fast reactive power compensation in order to isolate other customers from unacceptable voltage sags. This paper describes the planning and design considerations for application of distribution-class Static Synchronous Compensator (STATCOM) technology to mitigate power quality issues. The optimal size and location for application of a STATCOM has been determined. In addition, measurements were performed to benchmark the magnitude of voltage sag that can be experienced during motor starting. A detailed Electromagnetic Transient Program (EMTP) model of the system was developed to verify the proposed solution.