20040916-0840-Robert Broadwater-Real Time DG Control and Rel (1)

7/30/2019 20040916-0840-Robert Broadwater-Real Time DG Control and Rel (1)

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1

Robert Broadwater EDD

Blacksburg, Virginia

Real Time DG Control andReliability Improvements

2004 T&D Conference St. Louis, Missouri



2

Economics of DG GenerationDGs may sometimes be used to

avoid large capital investments,often to solve problems that onlyexist for a short period



3

Using DG to Correct Low Voltage



4

Zoom In to DG Site



5

DG Corrects Problem



6

Hierarchical Control

Units available for

economic dispatch

Level 2: Economic Dispatch of

Aggregated Units

Level 1: Local Control



7

Control System

Constraints

Set

points

to PI

Real-

time

measure

mentsfrom PI

Load

Scale

Historical measurements

Control

Power Flow



8

Historical Measurements

8760 hourly kW, kVar measurements for some large

customers12 kWHr measurements for other loads

–Load research statistics are usedto estimate kW, kVar loads



9

Glendale Circuit

Substation

DG



10

Distribution Transformer Models



11

Customer Types



12

Monthly kWHr Measurements



13

Control SystemConstraints

Set

points

to PI

Real-

time

measure

mentsfrom PI

Load

Scale


Control

Power Flow



14

Scaling of Model LoadsSome model loads are scaled to

cause power flow results to matchreal-time measurements

Non-scalable loads

Load scaling restrictions



15

Control System

Constraints

Set

points

to PI

Real-

time

measure

mentsfrom PI

Load

Scale


Control

Power Flow



16

Control of Voltages and CurrentsNo direct measurement of problems

Use model to predict problems

Use model to calculate generationlevels needed to eliminateproblems

–Low voltages

–Equipment overloads



17

DG Control Features

Control performed 24 X 7

Complete control calculation,including power flow, requires 1-2seconds per circuit

Calculates “just right” level of generation

Takes into account constraints



18

Amp Overload



19

Sub Amps

% Sub Loading

Overloaded Components

Output Report



20

Remaining CapacityAmps After DG

Control



21

Reliability for Time Varying Load

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

D o wn

T i m e ( Hr / yr )

Estimated Load Down Time



22

Case Study



23

Circuit Load and System Load Daily Load

1000

3000

5000

7000

9000

11000

13000

15000

17000

19000

21000

23000

25000

27000

29000

0 3 6 9 12 15 18 21

Time Point

F e e d e r F l o w ( K W )

C1

C2

C3

Sys



24

Optimum Locations

Optimal loss reduction

Best reliabilityimprovement



25

Analysis Results

DG Effects on System Reliability and Loss

Time point

3am 6am 12pm 6pm

C1_B3 C1_F4 DIF* C1_B3 C1_F4 DIF I_SW3 C3_B6 DIF Island_SW1 C1_F4 DIF

System

Loss (%) 4.15 4.14 0.01 4.21 4.19 0.02 4. 35 3. 90 0.45 5.45 3.81 1.64

SAIDISYSImprovement

(%) 27.74 25.81 1.93 20.25 20.25 0 42.41 35.44 6.97 20.25 18.99 1.26

* DIF stands for the difference of system loss and SAIDI improvement by placingthe DG at optimal loss location and optimal reliability location.



26

Economic Considerations

Assume 5 ¢ per kwHr

9am-5pm(1097kw – 975kw ) x 8hr x $.05 = $48.8

$48.8 = 6.97% reliability improvement ?



27

DG Placement for Best

Reliability

If DGs are to be shut down when

circuits experience outages, then DGsshould be placed in circuits that havethe lowest failure rates.

If DGs can be operated as islands, then

DGs should be placed in circuits thathave the highest failure rates.



28

ConclusionsDG placement in a circuit

DG placement in a system of circuits

Optimal DG placement

Documents

20040916-0840-Robert Broadwater-Real Time DG Control and Rel (1)