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