Nov 29, 2018

GENQSC & GENESC Dynamic Models

2

Equ

ival

ent C

ircui

t of M

ost C

omm

only

Use

d M

odel

s

From IEEE Std 1110-1991 & 2002

3

2nd-order Models, Complete vs “Standard”

From IEEE Std 1110-1991

“Complete / Accurate” “Standard”

“Standard” 2nd-order Model and Parameters

• The differential leakage inductance (Lf1d) is proportional to fluxes that link the d-axis damper winding and the field winding, but not linking the stator winding

• According to IEEE Std 1110-2002, Lf1d is often found to be positive for round-rotor generators and negative for salient-pole ones

• “Standard” 2nd-order model & parameters have Lf1d neglected

• Commonly-used “Standard” model representations are simplified from the accurate ones in table 1 of IEEE 1110

• Commonly-available “Standard” generator parameters from engineering analysis and testing have provided practical means in power system analysis

4

Standard 2nd-order Model, D-axis

5

Using Lad - base reciprocal per unit system

𝐿𝐿𝑑𝑑 𝑠𝑠𝑠𝑠𝑠𝑠 = 𝐿𝐿𝑠𝑠𝑑𝑑(𝑢𝑢𝑢𝑢𝑠𝑠𝑠𝑠𝑠𝑠) /(1 + 𝑆𝑆𝑠𝑠) + 𝐿𝐿𝑙𝑙 𝑆𝑆𝑠𝑠

𝐿𝐿11𝑑𝑑 (𝑠𝑠𝑠𝑠𝑠𝑠) = 𝐿𝐿11𝑑𝑑(𝑢𝑢𝑢𝑢𝑠𝑠𝑠𝑠𝑠𝑠) /(1 + 𝑆𝑆𝑠𝑠)

𝐿𝐿𝑓𝑓𝑓𝑓𝑑𝑑 (𝑠𝑠𝑠𝑠𝑠𝑠) = 𝐿𝐿𝑓𝑓𝑓𝑓𝑑𝑑 (𝑢𝑢𝑢𝑢𝑠𝑠𝑠𝑠𝑠𝑠) /(1 + 𝑆𝑆𝑠𝑠) 𝐴𝐴𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠:

Generator Model Field Current Compensation

6

Equivalent circuit with saturation and compensation of rotor leakage caused by stator current, in Lad-base reciprocal per unit system

GENQSC & GENESC Model Structure

7

GENQSC:

Quadratic Saturation function with field current Compensation

GENESC:

Exponential Saturation function with field current Compensation

No-load and load Saturations

8

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Gen

erat

or A

rmat

ure

Volta

ge a

nd C

urre

nt (p

.u.)

Generator Field Current (A)

Xp

OCC

SCC

0 P.F.

Air-gap // to Air-gap

// to Air-gap

Calculated Characteristics – Salient-pole

9

Manufacturer-provided curve

A 835 MVA Round-rotor Generator Field Current Error Comparison

10

0

1

2

3

4

5

6

7

8Er

ror o

f Mod

eled

Fie

ld C

urre

nt (%

)

Measured Field Current (p.u)

GENROU

GENTPJ/GENQSC-0

GENTPJ-0.18

GENQSC-0.085

81.2 MVA Salient-pole Unit 1 Field Current Error Comparison

11

0

1

2

3

4

5

6

7

8

9

10Er

ror o

f Mod

eled

Fie

ld C

urre

nt (%

)

Measured Field Current (p.u)

GENSAL

GENTPJ/GENQSC-0

GENTPJ-0.15

GENQSC-0.15

81.2 MVA Salient-pole Unit 2 Field Current Error Comparison

12

0

1

2

3

4

5

6

7

8

9

10Er

ror o

f Mod

eled

Fie

ld C

urre

nt (%

)

Measured Field Current (p.u)

GENSAL

GENTPJ/GENQSC-0

GENTPJ-0.15

GENQSC-0.15

49.1 MVA Salient-pole Unit 1 Field Current Error Comparison

13

0

1

2

3

4

5

6

7

8

9Er

ror o

f Mod

eled

Fie

ld C

urre

nt (%

)

Measured Field Current (p.u)

GENSAL

GENTPJ/GENQSC-0

GENTPJ-0.08

GENQSC-0.076

49.1 MVA Salient-pole Unit 2 Field Current Error Comparison

14

0

1

2

3

4

5

6

7

8

9

10

11

12

13Er

ror o

f Mod

eled

Fie

ld C

urre

nt (%

)

Measured Field Current (p.u)

GENSAL

GENTPJ/GENQSC-0

GENTPJ-0.08

GENQSC-0.076

GENQSC Dynamic Performance

15

4 4.5 5 5.5 6Time (sec)

1

1.02

1.04

1.06

1.08

Term

inal

Vol

tage

(p.u

.)

genqsc

gentpj

measured

4 4.5 5 5.5 6Time (sec)

0

5

10

Fiel

d Vo

ltage

(p.u

.)

genqsc

gentpj

measured

4 5 6 7 8

Time (sec)

40

42

44

46

48

Rea

l Pow

er (M

W)

genqsc

gentpj

measured

4 5 6 7 8

Time (sec)

0

5

10

15

Rea

ctiv

e Po

wer

(MVa

r)

genqsc

gentpj

measured

Offline 5% AVR Vref Step Online 3% AVR Vref Step

GENQSC Dynamic Performance

16

Online 3% AVR Vref Step

4 5 6 7 8

Time (sec)

1.4

1.6

1.8

2

Fiel

d C

urre

nt (p

.u.)

genqsc

gentpj

measured

4 5 6 7 8Time (sec)

1

1.01

1.02

1.03

1.04

Term

inal

Vol

tage

(p.u

.)

genqsc

gentpj

measured

Big difference in simulated generator field current between GENQSC and GENTPJ model. GENQSC matches actual measurement very well.

Conclusions

17

• Proposed GENQSC & GENESC models represent the electro-magnetic relations of generator stator and rotor

• New models consider the generator load-saturation curve, different from all existing dynamic models

• Rotor field current compensation independent from saturation functions (polynomial or exponential)

• Field current compensation factor can be derived from 0-pf saturation curve, or tested operating points

• Accuracy and dynamic performance improvement proven by field test data and simulation results