BPA/GE Load Model Improvements Project WECC MVWGMeeting June, 2017 Bill Price Juan Sanchez-Gasca

Load Model Improvements Project Objectives Implement several improvements to motor models on an experimental basis Compare model behavior with lab test results Make adjustments to models as needed Recommend changes for application to Composite Load Model Project Information Funded by BPA Implemented in PSLF by GE Completion by Dec. 31, 2017

Task 1 – New 3-phase motor model – MOTORLD Same electrical equations as MOTOR1 Speed exponent for torque instead of power Connect to a power-flow load instead of a generator Delete original undervoltage protection logic used in MOTOR1 Implement protection and control logic based on: - Contactor: - Controlled Trip:

Task 2: Updates to single-phase AC compressor motor models Upgrade to LD1PAC model to include new stall voltage versus time delay characteristic Add protection and control models from LD1PAC to MOTORC single-phase motor model

Task 3: Model Validation Testing Use BPA lab tests of air conditioner compressors and fans, including voltage sags, voltage ramps and off-nominal frequency. Compare model and test results, adjusting model and model parameters as appropriate. Prepare model validation report MOTORLD implemented, including contactor and controlled trip MOTORC protective tripping functions implemented LD1PAC – voltage dependent stall time (VDST) added BPA lab test results received – initial comparison simulations made Project Status – Tasks 1 & 2 completed

Voltage-dependent Stall Time (VDST) implementation For now, a single curve is hard-coded in LD1PAC: Invoked when Tstall parameter is set < 0. if (V < 0.57) then interpolate value of Tstall timer = timer + Dt / (Tstall/ 60.) if (timer >= 1) then stall (i.e. stay in stall mode after V recovery) Note: Tstall will change as V changes Voltage (p.u.) Stall time (cycles) > 0.57 no permanent stall 0.57 15 0.565 12 0.55 9 0.53 6 <= 0.46 3

Motor Controlled Trip (CT) Implementation V0, V1, V2, T1A, T2A, T1B, T2B and “fraction of motors with CT” are input parameters If (V < V0) start timer When timer reaches “fast trip” (red) line, trip a fraction of motor = (dT – T1) / (T2 – T1) As voltage changes, the operating line (black) will move up or down. If it moves down, T1 will be smaller, so a larger fraction will be tripped If it moves up, T1 will increase. Fraction already tripped will stay tripped, but additional tripping will be delayed until (dt – T1) exceeds its earlier value. Anytime V becomes > V0, the timer is reset. Subsequent excursions below V0 will restart the timer at 0. and, if dT becomes > T1, a fraction of the remaining load will be tripped. Any fraction that is tripped is never reconnected.