Sizing Reactive Compensation for a Steel Plant to Support a New Descaler With Large Motors

Abstract

A steel plant with two plate mills is adding new medium voltage 5000 HP motor loads to their existing power system in association with the new descaler project. These new inductive loads will increase the voltage drop and decrease the existing power factor at the 13.8 kV Turnip Hill Substation and the 138 kV point of common coupling. This paper first describes the investigation into the available options for supplying electrical power to the proposed new descale pumps at the 140 inch mill, supporting simultaneous operation with the 206 inch mill and the reasoning behind the chosen design. Next, the projected power flows to the descaler for various operating load levels of the mill are used to size reactive compensation. Several options for capacitor banks and filter banks of multiple steps are analyzed to determine the harmonic duty on the banks and reduction in harmonic distortion at the point of common coupling. A specification is given for the recommended filter bank as well as the solution that was implemented. Finally, performance data for the installed filter bank were given.