Single Phase Compressor Point-on-Wave Response Including tests done at BPA Bernie Lesieutre (UW-Madison, LBNL) Dmitry Kosterev Steve YangErik Lane (BPA) 1 WECC Load Modeling Task Force, June 17, 2015, Salt Lake City Lesieutre acknowledges support from CERTS and PSERC

Single Phase Compressor Simulation Model 2 T mech T ave mechanical revolution Reciprocating Compressor Mechanical Load

Current Research: Point-on-Wave Effects 3 Simulations of Single-Phase Compressor Motor Applied voltage. The disturbance occurs at different points along the sinusoid: peak, zero crossing, in between. Instantaneous drop to 62% nominal for 3 cycles. Speed for the different applied voltages. Worst case: zero crossing disturbance.

Current Research: Point-on-Wave Effects 4 Stall Voltage vs fault duration, and point-on-wave variation.

Current Research: Point-on-Wave Effects Ramp Voltage Instead: 5 Point-on-wave effect is greatly reduced for even a very short ramp. Performance Model Characteristic for reference

Current Research: Point-on-Wave Effects These results suggest a reason why FIDVR events don’t cascade. Locally, A/C motors stall in response to event. 6 Point-on-wave effect is greatly reduced for even a very short ramp. Performance Model Characteristic for reference Further away, the filtered voltage exceeds threshold.

Laboratory Tests Air Conditioner Tests at BPA Facility Test Point-on-Wave Response, with and without ramp. Scroll Compressor 7 Voltage dip to 48, 45, 40, 35 and 30% nominal Recovery voltage at 90% nominal. Find fault duration to result in a change in operating characteristic (not stall)

Fault Regions, Instantaneous Voltage Dip 8 Zero Crossing 45° Peak

Fault Region: 1 Cycle Ramp in Voltage Dip 9 Peak Zero Crossing45°

Key Point A slight ramp in the voltage disturbance characteristic greatly decreases the propensity to stall or abnormal operation. This may be a contributing factor to why FIDVR events appear to be localized. 10

Scroll Compressor: Three Operating States 11 1.Normal 2.Stall (Rotor stopped) 3.Single Winding Equivalent Mode?

Scroll Compressor: Three Operating States 12 1.Normal 2.Stall (Rotor stopped) 3.Single Winding Equivalent Mode? NormalAbnormal Vmain242.6 / 0 °242.2 / 0 ° Vaux381.0 / 87.1 °328.3 / ° Imain13.7 / °29.6 / ° Iaux 7.9 / 30.0 ° 8.3 / ° Itotal19.1 / °23.7 / °

Scroll Compressor: Abnormal Operation KW 2.2 KW 1.6 KW 5.1 KW 6.5 KW 1.4 KW Normal Power FlowAbnormal Power Flow Inefficient circulating power flow? 25% higher total energy use.

Active Power after a Fault 14