BPA Air Conditioner Test Results

Tests on November 22nd and 28th, 2016

Key Takeaways

• Stalling Depends on many factors• There is no single “correct” set of stall values to

use• These tests support the WECC phase 2 default

values of Vstall=0.45 and Tstall=2 cycles as reasonable conservative values

• More optimistic values that are still within the realm of reason are:– Vstall=0.45 and Tstall=5 cycles– Vstall=0.40 and Tstall=3 cycles or even 5 cycles

Factors which impact air conditioner stalling

• Factors impacting AC stalling– Voltage dip magnitude– Voltage dip duration– Time to ramp down from initial voltage to dip voltage– Final voltage (recovery voltage)– Time to ramp up from dip voltage to final voltage– Ambient temperature– Fault initiating on the positive crest, zero crossing, or

negative crest of the voltage wave cycle• With all of these factors, there is no single

“correct” value to use for Tstall and Vstall

Voltage Dip Test Variables

V

t

Vdip

Vrecovery

Tramp Trecovery

Tdip

Test Background

• These tests were conducted with a “Train” brand reciprocating compressor air conditioner

• Tests were conducted on Nov. 22nd with an ambient temperature in the mid 90s F, and Nov. 28th with an ambient temperature at about 100 F

Nov. 22nd BPA Lab Tests

• Tests assumed a 0.5 cycle ramp down to Vdip, ramp started at the crest, and an instantaneous recovery to 0.85 pu

• Key result here is that at Vdip=0.5 pu the air conditioner does not stall even for long dips (Tdip at 6 cycles, which is longer than 500 kV and 230 kV normal clearing times)

• The data here also supports Vstall=0.45 and Tstall=32 ms as conservative WECC default data

• May or may not stall for Vdip=0.45 and Tdip=3 cycles

Tdip Vdip POW recovery ramp, starts at Stalled? Contactors opened? date temp2 cycles 0.4 ramp 0.85 recovery 0.5 cycle ramp, crest yes yes 22-Nov mid 90's2 cycles 0.45 ramp 0.85 recovery 0.5 cycle ramp, crest no yes 22-Nov mid 90's3 cycles 0.45 ramp 0.85 recovery 0.5 cycle ramp, crest yes yes 22-Nov mid 90's3 cycles 0.5 ramp 0.85 recovery 0.5 cycle ramp, crest no no 22-Nov mid 90's4 cycles 0.5 ramp 0.85 recovery 0.5 cycle ramp, crest no no 22-Nov mid 90's5 cycles 0.5 ramp 0.85 recovery 0.5 cycle ramp, crest no no 22-Nov mid 90's6 cycles 0.5 ramp 0.85 recovery 0.5 cycle ramp, crest no no 22-Nov mid 90's9 cycles 0.5 ramp 0.85 recovery 0.5 cycle ramp, crest no no 22-Nov mid 90's

12 cycles 0.5 ramp 0.85 recovery 0.5 cycle ramp, crest yes no 22-Nov mid 90's

Nov. 28th BPA Lab Tests

• Tests assumed a 0.5 cycle ramp down to Vdip, ramp started at the zero crossing, and an instantaneous recovery to 0.85 pu

• Temperature was slightly higher than the Nov. 22nd tests, also we applied the ramp starting a zero crossing instead of starting at the crest

• Key result here is that recommending Vstall=0.45 and Tstall=0.032 s is conservative. A sensitivity study can decrease Vstall to 0.40 and Tstall to 3 cycles and still be within the realm of reason. Results show the air conditioner may or may not stall at this point

Tdip Vdip POW recovery ramp, starts at Stalled? Contactors opened? date temp2 cycles 0.45 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no no 28-Nov 1003 cycles 0.45 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no no 28-Nov 993 cycles 0.4 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no yes 28-Nov 993 cycles 0.4 ramp 0.85 recovery 0.5 cycle ramp, 0 xing yes yes 28-Nov 994 cycles 0.4 ramp 0.85 recovery 0.5 cycle ramp, 0 xing yes yes 28-Nov 99

Nov. 28th BPA Lab Tests (2)

• Tests assumed a 0.5 cycle ramp down to Vdip, ramp started at the zero crossing, and varied ramp up to recovery of 0.85 pu

• Temperature was slightly higher than the Nov. 22nd tests, also we applied the ramp starting a zero crossing instead of starting at the crest

• Key result here is that contactors consistently opened for Vdip=0.40 puand consistently did not open for Vdip = 0.45 pu, regardless of whether recovery voltage was instantaneous or ramped over a cycle

• Another result is that adding a 1 cycle ramp to the recovery voltage did not necessarily make the air conditioner more prone to stalling, at least not for Tdip=2 cycles.

Tdip Vdip POW recovery ramp, starts at Stalled? Contactors opened? date temp comments2 cycles 0.45 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no no 28-Nov 100 no recovery ramp2 cycles 0.45 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no no 28-Nov 100 0.5 cycle recovery ramp2 cycles 0.45 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no no 28-Nov 100 1 cycle recovery ramp2 cycles 0.4 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no yes 28-Nov 100 no recovery ramp2 cycles 0.4 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no yes 28-Nov 100 0.5 cycle recovery ramp2 cycles 0.4 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no yes 28-Nov 100 1 cycle recovery ramp

Nov. 28th BPA Lab Tests (3)

• Tests assumed a 0.5 cycle ramp down to Vdip, ramp started at the zero crossing, and varied ramp up to recovery to 0.85 pu

• Temperature was slightly higher than the Nov. 22nd tests, also we applied the ramp starting a zero crossing instead of starting at the crest

• Key result here is that when doing sensitivity studies it is reasonable to set Vstall=0.45 and increase Tstall to 5 cycles. Also, assuming a 1 cycle ramp up to the recovery voltage of 0.85 does not necessarily increase likelihood of stalling

Tdip Vdip POW recovery ramp, starts at Stalled? Contactors opened? date temp comments4 cycles 0.45 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no no 28-Nov 99 no recovery ramp4 cycles 0.45 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no no 28-Nov 99 0.5 cycle recovery ramp4 cycles 0.45 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no no 28-Nov 99 1 cycle recovery ramp5 cycles 0.45 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no no 28-Nov 99 0.5 cycle recovery ramp5 cycles 0.45 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no no 28-Nov 99 1 cycle recovery ramp

Nov. 28th BPA Lab Tests (4)

• Key result here is that assuming a 1 cycle ramp down for Vdipinstead of a 0.5 cycle ramp down significantly improvesperformance

• If a 1 cycle ramp is assumed, then Vstall=0.4 and Tstall=5 cycles is within the realm of reason

• For a 0.5 cycle ramp, the air conditioner may or may not stall for Vdip=0.40 and Tstall=3 cycles. This supports the WECC recommended Vstall=0.45 and Tstall=0.032 s as conservative parameters

Tdip Vdip POW recovery ramp, starts at Stalled? Contactors opened? date temp comments3 cycles 0.4 ramp 0.85 recovery 0.5 cycle ramp, 0 xing yes yes 28-Nov 100 no recovery ramp3 cycles 0.4 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no yes 28-Nov 99 no recovery ramp, repeat test4 cycles 0.4 ramp 0.85 recovery 0.5 cycle ramp, 0 xing yes yes 28-Nov 99 no recovery ramp3 cycles 0.4 ramp 0.85 recovery 1 cycle ramp, 0 xing no no 28-Nov 100 no recovery ramp3 cycles 0.4 ramp 0.85 recovery 1 cycle ramp, 0 xing no no 28-Nov 100 no recovery ramp, repeat test4 cycles 0.4 ramp 0.85 recovery 1 cycle ramp, 0 xing no no 28-Nov 100 no recovery ramp5 cycles 0.4 ramp 0.85 recovery 1 cycle ramp, 0 xing no no 28-Nov 100 no recovery ramp

Nov. 28th BPA Lab Tests (5)

• Key result here is that assuming a 0.5 cycle ramp instead of no ramp has a significant impact on performance

Tdip Vdip POW recovery ramp, starts at Stalled? Contactors opened? date temp2 cycles 0.4 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no yes 28-Nov 1002 cycles 0.4 ramp 0.85 recovery 0.5 cycle ramp, 0 xing no yes 28-Nov 1002 cycles 0.4 ramp 0.85 recovery no ramp, 0 xing yes yes 28-Nov 1002 cycles 0.4 ramp 0.85 recovery no ramp, crest yes yes 28-Nov 100

Nov. 28th BPA Lab Tests (6)

• Key result here is assuming the dip starts on a negative crest gives a different result from assuming the dip starts on a positive crest

• This may be because the air conditioner has an auxiliary winding with an in-run capacitor, so the positive voltage crest looks different from the negative voltage crest to the motor

• If a 0.5 cycle ramp is assumed, then Vstall=0.4 and Tstall=2 cycles is within the realm of reason

Tdip Vdip POW recovery ramp, starts at Stalled? Contactors opened? date temp2 cycles 0.4 ramp 0.85 recovery no ramp, crest yes yes 28-Nov 1002 cycles 0.4 ramp 0.85 recovery no ramp, crest, negative no no 28-Nov 100

Single Phase Motor Schematic

• Note the in-run capacitor on the aux winding• Because of this, a positive voltage peak looks

different than a negative voltage peak

13

Plots from Lab tests

• These plots are from Tests done November 22nd and November 28th, 2016 at BPA using a Train brand reciprocating AC

• Results are sorted in order of Vdip from highest to lowest (best to worst case)

• For a given Vdip, results are sorted by Tdipfrom lowest to highest (best to worst case)

346 348 350 352 354 356 358

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Vdip (% of initial voltage)

Recovery voltage

TdipPOW to start ramp down on

Ramp duration

date

365 370 375 380

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Aux winding voltage Main current

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360 362 364 366 368 370 372 374 376 378

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360 362 364 366 368 370 372 374 376 378

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380 385 390 395 400 405 410

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400 402 404 406 408 410 412 414 416 418 420

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356 358 360 362 364 366

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366 368 370 372 374 376

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357 358 359 360 361 362 363 364 365

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384 386 388 390 392 394

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324 326 328 330 332 334

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362 364 366 368 370 372 374 376 378

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352 354 356 358 360 362 364

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320 322 324 326 328 330 332 334

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546 548 550 552 554 556 558 560

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380 382 384 386 388 390 392

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392 394 396 398 400 402 404 406

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368 370 372 374 376 378 380 382

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340 342 344 346 348 350 352 354 356

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238 240 242 244 246 248 250 252 254

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378 380 382 384 386 388 390 392 394 396

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366 368 370 372 374 376 378 380 382 384

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358 360 362 364 366 368 370 372

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340 345 350 355 360

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352 354 356 358 360 362 364 366

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372 374 376 378 380 382

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355 356 357 358 359 360 361 362 363 364

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405 410 415 420 425 430 435 440

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362 363 364 365 366 367 368 369 370 371 372

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350 351 352 353 354 355 356 357 358 359

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348 350 352 354 356 358 360

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356 358 360 362 364 366 368

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242 244 246 248 250 252 254

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360 362 364 366 368 370

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370 372 374 376 378 380 382

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365 370 375 380 385 390 395

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354 356 358 360 362 364 366 368 370

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460 462 464 466 468 470 472 474 476

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350 352 354 356 358 360 362

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342 344 346 348 350 352 354

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320 325 330 335 340 345 350 355

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374 376 378 380 382 384 386 388

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334 336 338 340 342 344 346 348

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246 248 250 252 254 256

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