Power factor correction at the MIT-Bates Linear Accelerator Center with pulsed loads of up to 180 MW peak (2.7 MW average)

Power demand charges to MIT-Bates are based on a fixed rate times the greater of kWatt or 0.9 (kVolt A) called for in a 15 minute period within a billing cycle. There have been a number of months in a year when the power factor (PF) was less than 0.9 lagging, resulting in the increase in the demand charges to MIT by the Middleton Municipal Electric Department (MMED). A study resulted in a decision to correct the PF to >0.9 in order to minimize the demand charges. This action would save about $3500 per month in demand charges. Other benefits would also be realized by MIT-Bates and MMED, depending on the installation location. Information obtained on operational AC power requirements for the pulsed loads was obtained by measuring current and voltages at the 480 V inputs to the pulsed loads and at the incoming 22,900 V line input to the facility. A review of the harmonics generated in the voltage and current waveforms at both voltage levels for several operating levels allowed completion of an engineering analysis, which resulted in the selection of a 1200 kVAR switchable capacitor bank to be installed in a wye connection at the 22,900 V incoming line point just after the metering equipment. This paper describes the results of the harmonic studies of the AC power, the pulsed loads required as measured at 480 V, and the resultant overall harmonics generated at the 22,999 V level by the pulsed loads when combined with the other normal AC loads at the Laboratory.