Distribution capacitor automation provides integrated control of customer voltage levels and distribution reactive power flow

Southern California Edison Company's (SCE) capacitor automation project reduces overall net energy transfer from the substation to the customer while meeting system VAr requirements. The automated capacitor switching system developed by SCE uses new electronic meters to read real-time customer voltages and energy consumption. Two-way packet radios communicate this customer voltage data and capacitor status information to SCE computers, where a control algorithm determines the optimal capacitor-switching pattern, fine-tuning customer voltages to reduce energy consumption. Substation VAr data is integrated into the control scheme. Testing performed during the period January-December 1993 recorded an average reduction of 4.2 volts in customer voltages when the DCAP algorithm was not controlling switching of capacitors, compared against voltages when the DCAP algorithm was not controlling capacitor switching. SCE has implemented the system on 586 circuit capacitors (including 34 substation capacitors) on 174 circuits served from 20 substations.