1

Selecting Extended ReserveEmily Calvert, Energy Analyst

2

Contents

• Overview- Scheme- System

• Inputs- Unit load- Unit configuration

• Objective function- Meet block targets- Minimise cost

• Output- Procurement schedule

© Copyright NZX Ltd. 2015

AUFLS scheme• Two blocks• Each distributor obliged

© Copyright NZX Ltd. 20153

Extended Reserve scheme• Four blocks• Spread across North Island

OverviewExtended Reserve

Block Target Min Max

1 10 8 12

2 10 8 12

3 6 5 7.5

4 6 5 7.5

Block Min

1 16

2 16

4

Overview

© Copyright NZX Ltd. 2015

Extended Reserve system

5

Overview

Select standard and flexible demand units for each blocktaking into account penalties and constraints

1. Meet block targets2. Minimise costs

© Copyright NZX Ltd. 2015

Objective Function

Overview

• Mixed integer linear programming• Selects demand units to meet block targets• Includes penalties and constraints• Uses iterative sampling approach• Tests against other years’ data

© Copyright NZX Ltd. 20156

Selection Tool

Input

Identifier Date 00:00 00:30 01:00 01:30 02:00 …

ABCD0001 01/04/15 10 10 10 10 10

ABCD0002 01/04/15 5 5 5 5 5

ABCD0003 01/04/15 5 5 5 5 5

ABCD0004 01/04/15 2 2 2 2 2

ABCD0005 01/04/15 1 1 1 1 1

© Copyright NZX Ltd. 20157

Unit load

8

Input

© Copyright NZX Ltd. 2015

Unit load

0:00

1:00

2:00

3:00

4:00

5:00

6:00

7:00

8:00

9:00

10:00

11:00

12:00

13:00

14:00

15:00

16:00

17:00

18:00

19:00

20:00

21:00

22:00

23:00

DU1 DU2 DU3 DU4 DU5

9

Input

© Copyright NZX Ltd. 2015

Unit load

0:00

1:00

2:00

3:00

4:00

5:00

6:00

7:00

8:00

9:00

10:00

11:00

12:00

13:00

14:00

15:00

16:00

17:00

18:00

19:00

20:00

21:00

22:00

23:00

DU1 DU2 DU3 DU4 DU5

10

Input

© Copyright NZX Ltd. 2015

Calculate block requirements

0:00

1:00

2:00

3:00

4:00

5:00

6:00

7:00

8:00

9:00

10:00

11:00

12:00

13:00

14:00

15:00

16:00

17:00

18:00

19:00

20:00

21:00

22:00

23:00

Blocks

Input

Identifier

# current relays

# new relays

Currently allocated

Fast response Flexible …

ABCD0001 1 0 1 Y S

ABCD0002 1 0 2 N M

ABCD0003 0 0 0 N N

ABCD0004 0 0 0 N P

ABCD0005 0 0 0 N N

© Copyright NZX Ltd. 201511

Unit configuration: Capabilities

Input

IdentifierResidential

Light & Primary Industry

Heavy Industry

Commercial

Public Health &Safety …

ABCD0001 0.0 0.0 1.0 0.0 0.0

ABCD0002 0.0 0.0 0.8 0.2 0.0

ABCD0003 0.5 0.4 0.0 0.0 0.1

ABCD0004 1.0 0.0 0.0 0.0 0.0

ABCD0005 1.0 0.0 0.0 0.0 0.0

© Copyright NZX Ltd. 201512

Unit configuration: Customer classes

13

Selecting Extended Reserve

Minimise objective =

relay cost + flex relay cost + interruption cost

+ block penalty + fast relay cost – fast relay benefit

© Copyright NZX Ltd. 2015

Objective Function

14

Selecting Extended Reserve

Block 1(EIH 0.278)

Block 2 (EIH 0.136)

Block 3(EIH 0.054)

Block 4(EIH 0.032)

Type A: Standard

$4,000+ $0

+ $4,420= $8,420

$4,250+ $0

+ $2,162= $6,412

$4,250+ $0

+ $859= $5,109

$4,350+ $0

+ $509= $4,859

Type B: Flexible

$4,000+ $500

+ $4,420= $8,920

$4,250+ $500

+ $2,162= $6,912

$4,250+ $500+ $859

= $5,609

$4,350+ $500+ $509

= $5,359

© Copyright NZX Ltd. 2015

Cost varies across reserve type and block

Example of costs for demand unit ABCD0004Assume Block 1, 100% residential, average demand 1MW

Most likely to be used

Least likely to be used

15

Selecting Extended Reserve

Minimise objective =

relay cost + flex relay cost + interruption cost

+ block penalty + fast relay cost – fast relay benefit

© Copyright NZX Ltd. 2015

Objective Function

Selecting Extended Reserve

© Copyright NZX Ltd. 201516

Penalties – finding the Goldilocks Zone

Max

Min

© Copyright NZX Ltd. 2015

Selecting Extended Reserve

17

Constraints

Block 4

Block 3

Block 2

Block 1

0 2 4 6 8 10 12

© Copyright NZX Ltd. 2015

Selecting Extended Reserve

18

Constraints

Block 4

Block 3

Block 2

Block 1

0 2 4 6 8 10 12

© Copyright NZX Ltd. 2015

Selecting Extended Reserve

19

Constraints

Block 4

Block 3

Block 2

Block 1

0 2 4 6 8 10 12

Output

Identifier Allocated Flexible Armed Standby …

ABCD0001 Y Y Y N

ABCD0002 N N N N

ABCD0003 Y N N N

ABCD0004 Y N N Y

ABCD0005 N N N N

© Copyright NZX Ltd. 201520

Procurement schedule

21

Summary

• Overview- Scheme- System

• Inputs- Unit load- Unit configuration

• Objective function- Meet block targets- Minimise cost

• Output- Procurement schedule

© Copyright NZX Ltd. 2015

22

Questions?

© Copyright NZX Ltd. 2015