Frequency Response and Dynamic Power Balancing in Wind &...

SEPTEMBER 4 - 6, 2019

Frequency Response and Dynamic Power Balancing in Wind & Solar Generation

Srijib Mukherjee, Ph.D., P.E.Principal Engineer, Power Delivery

Mott MacDonald


Frequency Regulation versus Load Following

Regulation is the use of online generation that is equipped with AGC, storage or load that can change output quickly to track moment to moment fluctuation in customer load Regulation tracks unintended fluctuations in generation

Maintains interconnection frequency by managing actual and schedule power flows between balancing areas and correcting for frequency error

Load Following (ramp capability) is the use of online generation, storage or load equipment to track inter and intra hour changes in load. Occurs over longer intervals

Load following patterns are predictable


Frequency Regulation versus Load Following

Regulation Load Following

Patterns Random Highly predictable

Control Requires AGC Can be manual

Maximum Swing Small 10 to 20 times regulation

Ramp Rate (MW/min) 5 to 10 times load following Slow

Sign Changes per unit time

20 to 50 times load following Few


Methodology to determine Ramp Magnitude

Methodology to Determine Ramp Magnitude

Utility 1-minute load and wind/solar data from SCADA historian

Use of Utility 5-minute solar data if available

Down sample to a 10-minute resolution level

Dashboard with the following information: Current Year

Year of Analysis

Annual load growth

Peak expected Wind in year of analysis (MW)

Peak expected Solar PV in year of analysis (MW)


Methodology to determine Ramp Magnitude

Methodology to Determine Ramp Magnitude

EXCEL Tool display existing data and calculates future: Current year system peak in MWs

Peak load in year of analysis in MWs

Current year peak Wind in MWs

Current year peak Solar PV in MWs

Wind penetration in year of analysis as a percent

Solar penetration in year of analysis as a percent

Total renewable penetration in year of analysis as a percent

The load ramp rate in MW/min is the difference of the value of that 10 minute period and the previous 10 minute period divided by 10 (slope)


Utility: Annual load growth = 3% (assumption)Peak Wind for 2020 = 5,000 MWPeak Solar for 2020 = 1,500 MWTotal Wind Penetration with respect to peak load in 2020 = 15.8%Total Solar Penetration with respect to peak load in 2020 = 4.7%

Average Load ramp up rate in Year of Analysis: 13.24 MW/min

Maximum Load ramp up rate in Year of Analysis: 434.94 MW/min

Average Load ramp down rate in Year of Analysis: -12.73 MW/min

Maximum Load ramp down rate in Year of Analysis: -370.82 MW/min

Average Load-Wind ramp up rate in Year of Analysis: 15.23 MW/min

Maximum Load-Wind ramp up rate in Year of Analysis: 477.84 MW/min

Average Load-Wind ramp down rate in Year of Analysis: -14.66 MW/min

Maximum Load-Wind ramp down rate in Year of Analysis: -372.00 MW/min

Average Load-Wind-Solar ramp up rate in Year of Analysis: 15.56 MW/min

Maximum Load-Wind-Solar ramp up rate in Year of Analysis: 479.34 MW/min

Average Load-Wind-Solar ramp down rate in Year of Analysis: -15.19 MW/min

Maximum Load-Wind-Solar ramp down rate in Year of Analysis: -372.00 MW/min

20% Reference Case Results – Utility


National Grid: Annual load growth = 3%Peak Wind for 2020 = 9,000 MWPeak Solar for 2020 = 4,000 MWTotal Wind Penetration with respect to peak load in 2020 = 13.8%Total Solar Penetration with respect to peak load in 2020 = 6.1%













20% Reference Case – National Grid


20% Reference

Case –Graphed Results

0.0020.0040.0060.0080.00

100.00120.00140.00160.00180.00200.00

0 4272 8544 12816 17088 21360 25632Time (10 min)

Ram

p ra

te (M

W/m

in)

2020 CAISO Load Ramp rate (MW/min)

2020 CAISO Load-Wind Ramp rate (MW/min)2020 CAISO Load-Wind-Solar Ramp rate (MW/min)

2020 SCE Load Ramp rate (MW/min)

2020 SCE Load-Wind Ramp rate (MW/min)2020 SCE Load-Wind-Solar Ramp rate (MW/min)

-200.00

-180.00

-160.00

-140.00

-120.00

-100.00

-80.00

-60.00

-40.00

-20.00

0.0025632 29952 34272 38592 42912 47232 51552

Time (10 min)

Ram

p ra

te (M

W/m

in)






Utility: Annual load growth = 3%Peak Wind for 2020 = 8,000 MWPeak Solar for 2020 = 2,500 MWTotal Wind Penetration with respect to peak load in 2020 = 25.2%Total Solar Penetration with respect to peak load in 2020 = 7.9%













33% Reference Case Results - Utility


National Grid: Annual load growth = 3%Peak Wind for 2020 = 14,000 MWPeak Solar for 2020 = 8,000 MWTotal Wind Penetration with respect to peak load in 2020 = 21.5%Total Solar Penetration with respect to peak load in 2020 = 12.3%













33% Reference Case Results – National Grid


0.0020.0040.0060.0080.00

100.00120.00140.00160.00180.00200.00

0 4272 8544 12816 17088 21360 25632Time (10 min)

Ram

p ra

te (M

W/m

in)





-200.00

-180.00

-160.00

-140.00

-120.00

-100.00

-80.00

-60.00

-40.00

-20.00

0.0025632 29952 34272 38592 42912 47232 51552

Time (10 min)

Ram

p ra

te (M

W/m

in)





30% Reference

Case –Graphed Results


Aggregated Generator Ramp Capability

-1000-800 -600 -400 -200 0 200 400 600 800 10000

10

20

30

40

50

60

Ramp rate capability (MW/min)

% o

f occ

uran

ce

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

x 105

-1000

-500

0

500

1000

Time (min)

Ram

p ra

te (M

W/m

in)

Ramp rate capability comparison of SCE for 2008

Ramp up capability (MW/min)Ramp down capability (MW/min)Load ramp rate (MW/min)


Utility’s 1-minute Load Ramp Rate Requirement

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

x 105

-1000

-800

-600

-400

-200

0

200

400

600

800Load ramp rate for 2008 (MW/min)

Time (min)

Ram

p ra

te (M

W/m

in)

-1000 -800 -600 -400 -200 0 200 400 600 8000

1

2

3

4

5

6x 10

5 Histogram of load ramp rate

Ramp rate (MW/min)

Freq

uenc

y


-1000 -800 -600 -400 -200 0 200 400 600 8000

1

2

3

4

5

6x 10

5

Ramp rate (MW/min)

Freq

uenc

y

Histogram of load-wind ramp rate

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

x 105

-100

-80

-60

-40

-20

0

20

40

60

80

100

Time (min)

Ram

p ra

te (M

W/m

in)

Ramp rate comparison for 2008

Load ramp rate (MW/min)Load-Wind ramp rate (MW/min)

Utility’s 1-minute Load-Wind Ramp Rate Requirement


Using the Utility’s 1-minute load and wind data from 2010, find: Mean, median, minimum and maximum for every instance in

time of day for the month

Calculate standard deviation for every minute in time of day for the month

Normalize the standard deviation to the mean for minute instance in time of day for the month

Calculate the hourly normalized standard deviation for each hour of the day

The highest peak of the distribution reflects the worst hour variability from mean

Statistics worst hourly ramp impacts


Worst hourly changes for load, wind and load-wind

On peak changes for load, wind and load-wind

Off peak changes for load, wind and load-wind

Morning changes for load, wind and load-wind

Evening changes for load, wind and load-wind

Metrics


Load

Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Worst hourly change 7:00 7:00 7:00 16:00 16:00 16:00 7:00 8:00 15:00 15:00 14:00 7:00

Worst On Peak hourly change (from 07:00 to 18:00) 7:00 7:00 7:00 16:00 16:00 16:00 7:00 8:00 15:00 15:00 14:00 7:00

Worst Off Peak hourly change (from 19:00 to 06:00) 6:00 6:00 6:00 6:00 19:00 19:00 6:00 6:00 6:00 6:00 6:00 6:00

Worst hourly morning change (from 06:00 to 10:00) 7:00 7:00 7:00 7:00 10:00 10:00 7:00 8:00 6:00 10:00 7:00 7:00

Worst hourly evening change (from 17:00 to 21:00) 17:00 17:00 17:00 17:00 17:00 17:00 17:00 17:00 17:00 17:00 17:00 17:00

Wind







Load-Wind







Worst hourly metrics for load, wind and load-wind


Load

Hourly Norm Std Dev for Jan 08

0.000000

0.020000

0.040000

0.060000

0.080000

0.100000

0.120000

0:00:0

0

2:00:0

0

4:00:0

0

6:00:0

0

8:00:0

0

10:00

:00

12:00

:00

14:00

:00

16:00

:00

18:00

:00

20:00

:00

22:00

:00

Wind

Hourly Norm Std dev for jan 08

0.000000

0.200000

0.400000

0.600000

0.800000

1.000000

1.200000

0:00:0

0

2:00:0

0

4:00:0

0

6:00:0

0

8:00:0

0

10:00

:00

12:00

:00

14:00

:00

16:00

:00

18:00

:00

20:00

:00

22:00

:00

Norm Std Deviations for load and wind: Jan 08


Norm Std Deviations load-wind:

Jan 08

Norm Std Dev for Load - Wind for Jan 08

0

0.02

0.04

0.06

0.08

0.1

0.12

0:00:0

0

2:00:0

0

4:00:0

0

6:00:0

0

8:00:0

0

10:00

:00

12:00

:00

14:00

:00

16:00

:00

18:00

:00

20:00

:00

22:00

:00

Nor

m S

td D

ev


Benefits of Aggregation –Wind Sites in SCE

Riverside (January 2005)

-10

-5

0

5

10

0 5 10 15 20 25 30 35

Wind Power (MW)

Ram

p ra

te (%

)

San Diego (January 2005)

-10

-5

0

5

10

0 5 10 15 20 25 30 35

Wind Power (MW)

Ram

p ra

te (%

)



Merced (January 2005)

-6

-4

-2

0

2

4

6

0 5 10 15 20 25 30 35

Wind Power (MW)

Ram

pra

te (%

)

San Bernardino (January 2005)

-10

-5

0

5

10

15

0 5 10 15 20 25 30 35

Wind Power (MW)

Ram

p ra

te (%

)



Aggregated Wind (January 2005)

-10

-5

0

5

10

0 50 100 150 200 250 300 350 400

Wind Power (MW)

Ram

p ra

te (%

)

San Joaquin (January 2005)

-15

-10

-5

0

5

10

0 5 10 15 20 25 30 35

Wind Power (MW)

Ram

p ra

te (%

)


GE-PSLFAGC Testing (Preliminary

Study )


Ramp rate requirements do not change significantly for both Utility and National with a 33% RPS penetration of intermittent resources

From the statistical analysis the worst ramp impacts occur in the morning hours during the winter and spring months; and late afternoon in late spring, early summer and fall

Aggregation of Wind farms and Solar PV systems in Southern California helps minimize ramp rate requirements thereby providing better usage of spinning reserves.

Energy storage devices such as batteries and flywheels can help as frequency response reserves to instantaneous changes in ramp requirements.

We are investigating the use of the GE-PSLF tool to understand the effects of governor response to changes in variable load and AGC (this will be completed and reported in phase 2 of the project).

Conclusions


Impacts of regulation within CAISO and SCE using a Monte Carlo statistical approach to study the behavior of wind and solar Correlation impacts of wind speed to wind output

Correlation of solar irradiance and cloud cover to solar output

Study effects of governor response to a variable load profile – impacts of AGC due to the effects of intermittent resources

Next Steps


Questions?

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Frequency Response and Dynamic Power Balancing in Wind &...

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