caiso presentation

8/7/2019 CAISO Presentation

http://slidepdf.com/reader/full/caiso-presentation 1/16

Sensitivity Studies

Northern California

Irina GreenCalifornia ISO

For Modeling and ValidationWorkshop, November 2006



STUDY ASSUMPTIONS

• Operational case of July 29, 2003• Three-phase faults followed by opening of

the transmission lines in NorthernCalifornia

• Used BPA epcl. Added distribution

feeders and transformers• Load – 1 induction motor, resistive, and

constant power

• All loads throughout WECC modeled thesame way



OUTAGES STUDIED

1. 230 kV line with a 6 cycle 3-phase fault at themost heavily loaded bus (Elk Grove-Rancho

Seco).2. Heavily loaded 230 kV line with a 6 cycle 3-

phase fault in an area that has an underline 60

kV system with long feeders (Tesla-Newark).3. The most heavily loaded 230 kV line with a 6

cycle three-phase fault (Newark-Ravenswood).

4. Heavily loaded 500 kV line with a 5 cyclethree-phase fault (Table Mountain-VacaDixon).

• Which outage is the worst?



Induction Motor Parameters

Component Description XS XP TP H RS

Resid. Central Air Cond. or heat pump 2.476 0.135 0.136 0.28 0.033

Resid. Room Air Cond. 1.900 0.158 0.055 0.28 0.1

Resid. Refrigerator & Freezer 2.487 0.164 0.124 0.28 0.056

Resid. Dishwasher 2.940 0.199 0.069 0.28 0.11

Resid. Clothes Washer 2.120 0.242 0.051 0.69 0.11

Resid. Clothes Dryer 2.050 0.280 0.042 0.11 0.12

Comm. Central Air Cond. or heat pump 2.023 0.151 0.148 0.28 0.053

Comm. Pumps, Fans & other Motors 3.320 0.236 0.169 0.7 0.079

Ind. Heavy-Sm. Ind. Motors (5-200HP) 3.300 0.270 0.498 0.7 0.031

Ind. Heavy-Lg. Ind. Motors (200-UP HP) 3.867 0.230 1.170 1.5 0.013

Agricul. Pumping for Irrigation 3.288 0.249 0.559 0.8 0.025

Power Plant Auxiliaries 2.540 0.254 0.742 1.5 0.013

Res AC 2.476 0.135 0.136 0.28 0.033

1 ph motor 2.530 0.262 0.061 0.3 0.11

Comerc AC 2.023 0.151 0.148 0.28 0.0533ph motor 3.480 0.251 0.949 1 0.2



Sensitivity to Percentage of Motor Load

a - 5% feeder voltage drop, 100% resistive loadb - 5% feeder voltage drop, 60% resistive load, 40% constant powerc- 5% feeder voltage drop, 30% motor load, other static

d- 5% feeder voltage drop, 60% motor load, other static worst casee- 3% feeder voltage drop, 60% motor load, other staticf-1% feeder voltage drop, 60% motor load, other static



Sensitivity to Motor Inertia

Motor parameters in the original case.Ls = 3.1 L’ = 0.2 Ra = 0.025 T’0 = 0.33H = 0.3 D = 3Sensitivity to inertia constant.1) H= 0.1, 2) H=0.25, 3) H = 0.3, 4) H= 0.7, 5) H = 1.5

Case comparison (stalled motor)A – H=0.1, b- H = 0.25, c- H = 0.3, d – H = 0.7, e – H = 1.5



Sensitivity to Motor Inertia

Motor parameters in the original case.Ls = 3.1 L’ = 0.2 Ra = 0.025 T’0 = 0.33H = 0.3 D = 3Sensitivity to inertia constant.1) H= 0.1, 2) H=0.25, 3) H = 0.3, 4) H= 0.7, 5) H = 1.5

Case comparison (recovered motor)A – H=0.1, b- H = 0.25, c- H = 0.3, d – H = 0.7, e – H = 1.5



Sensitivity to Time Constant

Motor parameters as in the original case, but different time constants.

Ls = 3.1 L’ = 0.2 Ra = 0.025 T’0 = 0.33H = 0.3 D = 3

Case comparison

a)T’ = 0.1 b)T’ = 0.33 (base case) c)T’ = 0.4 d)T’ = 0.5 e)T’ = 1



Sensitivity to Motor-Driven Load

IMPACT OF DAMPING

a) D= 0.5 b) D=1 c) D=2, d) D= 3 (base case) e) D=4

Case comparisona) D= 0.5 b) D=1 c) D=2, d) D= 3 (base case) e) D=4



Sensitivity to Transient Reactance

Motor parameters as in the original case, but different L’:

Ls = 3.1 L’ = 0.2 Ra = 0.025 T’0 = 0.33H = 0.3 D = 3

Case comparisona) L’ = 0.1 b) L’= 0.2 (base case) c) L’ = 0.25 d) L’ = 0.3



Sensitivity to Synchronous Reactance

Motor parameters as in the original case, but different Ls.

Ls = 3.1 L’ = 0.2 Ra = 0.025 T’0 = 0.33H = 0.3 D = 3

Case comparisona) Ls=1 b) Ls = 2 c) Ls = 2.5 d) Ls = 3.1 (base case) e) Ls = 4



DO MOTORS RECOVER?H=0.1, Ls = 3.1, L’ = 0.2, Ra = 0.025

T’0 = 0.33 D = 3



DO MOTORS RECOVER?H=0.3, Ls = 3.1, L’ = 0.2, Ra = 0.025

T’0 = 0.33 D = 1



FREQUENCY WHEN MOTORS STALLH=0.3, Ls = 3.1, L’ = 0.2, Ra = 0.025

T’0 = 0.33 D = 1



Conclusions

1. System dynamic stability performance appeared to be verysensitive to induction motor load parameters. Thissensitivity was especially critical for severe disturbances.The most critical parameters appeared to be percentage ofinduction motor load, damping coefficient, motor inertia androtor resistance.

2. The faults that were close to the load appeared to be more

critical than the faults on the 500 kV system and outages of500 kV lines. The system performance was worse for theoutages and faults in the area of long lower voltage linesand mesh networks.

3. Only motor-driven load (constant torque) showed the motorsthat completely stalled. Other critical parameters (lowinertia, low rotor resistance) showed significant slowing

down of the motors and depressed voltage, but the voltageand motor speed later recovered.

(next page)



Conclusions– cont’d

4. Mix of commercial and industrial motors appeared to be moreprone to stall than other motors due to their low rotorresistance and low inertia.

5. The study showed that the system frequency might go upwhen induction motors stall, even if some generators that

go-out-of-step are tripped, because the motor loadbecomes very low.

6. It is important to obtain accurate load models because thesystem dynamic stability performance is extremely sensitiveto the motor parameters.

caiso presentation

Documents