7/28/2019 T2 C Power Flow Control

1/21

1 Managed by UT-Battellefor the Department of Energy

Power Flow Control Using

Distributed Saturable Inductors

Aleks Dimitrovski

ORNL

7/28/2019 T2 C Power Flow Control

2/21

2 Managed by UT-Battellefor the Department of Energy

Power System Flows

,S SP Q

/S

V 0/R

V Z jX

2 cossinS R S S RS S

V V V V V P Q

X X

7/28/2019 T2 C Power Flow Control

3/21

3 Managed by UT-Battellefor the Department of Energy

Simple Example

3 x 150 MVA lines supply 250 MW load

All lines: z= 0.125 + j0.52 /mi, y= j6.8 S/mi

7/28/2019 T2 C Power Flow Control

4/21

4 Managed by UT-Battellefor the Department of Energy

Simple Example

Uncontrolled Power Flow

7/28/2019 T2 C Power Flow Control

5/21

5 Managed by UT-Battellefor the Department of Energy

Uncontrolled Flows Cause Problems

Overloading of lines and transformers

Reduced security margins

Power exchange contractual violations

Increased fault levels beyond rating

7/28/2019 T2 C Power Flow Control

6/21

6 Managed by UT-Battellefor the Department of Energy

and Inefficiencies

Increased system losses

Reduced power transfer capabilities

Opposite reactive power flows

Loop flows

loop flow,reactive power

actual realpower transfer

7/28/2019 T2 C Power Flow Control

7/21

7 Managed by UT-Battellefor the Department of Energy

Limited Flow Control

Switching elements on/off Regulating Transformers

Off-nominal turns ratio

Phase-shifters

Switchable shunt/series capacitors andinductors

FACTS - Flexible AC Transmission SystemDevices

7/28/2019 T2 C Power Flow Control

8/21

8 Managed by UT-Battellefor the Department of Energy

FACTS Devices Expensive and Bulky

100 MVAr

STATCOM

84 MVArCap Bank

TVA Sullivan S/S near Johnson City

7/28/2019 T2 C Power Flow Control

9/21

9 Managed by UT-Battellefor the Department of Energy

Air-Core Inductors Cheaper but Coarse

PNM Norton S/S near LANL

15 Air-CoreSeries Inductor

14,500 lbs

7 ft

6 ft

10 ft

7/28/2019 T2 C Power Flow Control

10/21

10 Managed by UT-Battellefor the Department of Energy

Cost Comparison

Norton air-core inductor,120 MVA:~ $1,000,000 (current estimate)

Equivalent FACTS device:

> $10,000,000

This proposal:

~ $100,000

7/28/2019 T2 C Power Flow Control

11/21

11 Managed by UT-Battellefor the Department of Energy

Simple Example

Inductor Controlled Power Flow

24.9 (66 mH)

7/28/2019 T2 C Power Flow Control

12/21

12 Managed by UT-Battellefor the Department of Energy

Simple Example

Different Load Distribution inductor On

7/28/2019 T2 C Power Flow Control

13/21

13 Managed by UT-Battellefor the Department of Energy

Simple Example

Different Load Distribution inductor Off

7/28/2019 T2 C Power Flow Control

14/21

14 Managed by UT-Battellefor the Department of Energy

Simple Example

Different Load Distribution inductor Changed

14.8 (39 mH)

7/28/2019 T2 C Power Flow Control

15/21

15 Managed by UT-Battellefor the Department of Energy

Iac Nac

l

Ndc

DC Source

Power line

(controlled circuit)

Idc

dc bias flux

control circuit

A

mdcac

Magnetic Amplifier

2

( )

acac

dc

N AL constl

f I

m m

m

ac circuit inductance :

controlled by dc circuit current :

7/28/2019 T2 C Power Flow Control

16/21

16 Managed by UT-Battellefor the Department of Energy

BH Curve of Ferromagnetic Core

1~2 T

B

H

small

Idc1 < Idc2

large

7/28/2019 T2 C Power Flow Control

17/21

17 Managed by UT-Battellefor the Department of Energy

Iac

ac

Nac/2

Ndc/2

DC Source

Idc

Nac/2

Ndc/2

acdc dc

Symmetrical Connection

Equal performance in both half-cycles

Cancellation of the induced voltage in the dc circuit

7/28/2019 T2 C Power Flow Control

18/21

18 Managed by UT-Battellefor the Department of Energy

Iac

ac

Nac/2

DC Source

Idc

Nac/2

Ndc dc

Single-Core Symmetrical Connection

Three-legged core

No induced voltage in the dc circuit

7/28/2019 T2 C Power Flow Control

19/21

19 Managed by UT-Battellefor the Department of Energy

Iac

ac

Ndc/2

DC Source

Idc

Ndc/2Nac

dc gaps

Single-Core with Swapped Windings

Exclusive path for ac flux instead of dc through the middle leg

Bias dc flux not impeded by gaps in the core

7/28/2019 T2 C Power Flow Control

20/21

20 Managed by UT-Battellefor the Department of Energy

Local DC Saturation

Iac

Nacl

Ndc/2

Idc

dc

ac

Ndc/2

gaps

DCS

ource

7/28/2019 T2 C Power Flow Control

21/21

21 Managed by UT-Battellef h f

Conclusions

Magnetic amplifier based device for continuouspower flow control

Combination of proven and familiar conceptswith new technology

Cheap enough for system-wide deploymentand comprehensive power flow control

Makes the grid part smart in smart grid,besides generation and load