bstp dyn istanbul 20110518 (3)
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Power system analyses(Dynamic modeling)
Using PSS/E for power system analyses- Turbine & Turbine Governor modeling -
Istanbul, May 2011
IntroductionIt is important to model turbine governing and turbine of a generator due to the crucial influence to the power and frequency in a system during the entire dynamic process.Largest influence in:
maintaining power balance between mechanical and electrical power of generation unitmaintaining frequency of the power system, capability of machine to dampen the small signal oscillations (small signal stability)
Least influence in Reactive Power-Voltage loop (QV control)
Introduction
There are three types of conventional power plant turbines:
Hydro turbinesSteam turbinesGas turbines
Recently wind turbines for wind farms emerge as a new large scale power source
Principle scheme of turbine governing
Governing systems
Turbine governors are also separated into two types depending on their purpose:
Static droop governors (used for steam and gas turbines)
Static & Transient droop governors (used for hydro turbines)
σ1
=K Main servomotor with oil distributor
Main servomotor with oil distributor
Mechanical damping circuit
Hydro turbines
Type of hydro power plant dictates technical parameters (construction)
Run of riverHigh dam (storage)
DerivationTurbine type
PeltonFrancisBladeKaplan
Hydro turbines
Primary driving force is water which is conducted from a water reservoir or from a river flowFirst actual power plant was hydropower plant Usually separated by the Net Head to:
Pelton turbines (500m<Net Head )Francis turbines (<Net Head)Kaplan turbines (low Net Head and run of river)Propeller (Bulb) turbines (run of river)
Hydro turbines
Advantages:High controllability of power generationFast rate of power change
drawbacks:Highly nonlinear element (many physical values affect the operation)Slow response during the transient processesLimitation of maximum unit power up to 600 MW
Hydro turbines and governors
There are several models for hydro turbines in PSS/E library:
generic models: IEEEG3, PIDGOV, HYGOV2more detailed models: HYGOV, HYGOVM, WEHGOV, WSHYDD
nG
h0 = static head of water columnl = length penstockA = area penstockq = turbine flow rateh = head at the turbine admissionnG (ωG) = generator speed
PTurbine
Dampingfunction
h
+
G q
-
no load flow
+-
proportionalityfactor Turbine
Gate
– setpointspeed
Governorspeed
Governor
1
0 Servomotor Gate
–
Turbine Generator Transformer Network
friction
water time constant
water
hf head loss due friction
hq
Ah0= 1
q Pmech PG
mechanical electricalPower Power
ValveGate
lT G
speed limitclose
speed limitopen
speed limitclose
speed limitopen
speed limitclose
speed limitopen
permanent and transient Droop
servo
gain
servo
gain
h
–
–
GgGg
s1s1
ΣΣΣΣ
efGRn
Gn
2
⎟⎠⎞
⎜⎝⎛=Ggh WsT
1
ΣΣ ΣΣ
nlgpuh 10 =
fh
TATA ΣΣ
DD
gnΔ
sT+11sT+1
1
ππ
ππππ
Hydro turbines
Recommendation is to use IEEEG3 and for more detailed representation use HYGOV
Hydro turbines
1a23 (>0)
1.5a21
1a13
0.5a11 (>0)
1.16TW (>0) (sec)
6TR, (>0) (sec)
0.31δ
0.05σ
0PMIN
0.95PMAX
-0.167Uc (<0.)(pu per sec)
0.167Uo (pu per sec)
0.04TP (>0) (sec), pilot value time
0.2TG, (>0) (sec)
1a23 (>0)
1.5a21
1a13
0.5a11 (>0)
1.16TW (>0) (sec)
6TR, (>0) (sec)
0.31δ
0.05σ
0PMIN
0.95PMAX
-0.167Uc (<0.)(pu per sec)
0.167Uo (pu per sec)
0.04TP (>0) (sec), pilot value time
0.2TG, (>0) (sec)
In case of absence of data about certain HPP, use IEEEG3 with default parameters
Hydro turbine partGovernor part
Hydro turbines
Parameter ranges for IEEEG3 and HYGOV
Static and transient droops
Steam turbines
Primary driving force is steam which is conducted from a boiler, heat exchanger or nuclear reactor Usually separated to the pressure stages:
High pressure stageMedium pressure stage (reheat stage)Low pressure stage
Main energy conversion tool in the world
Steam turbines
Advantages:Installed powers up to 1500 MW
drawbacks:Slow start, slow stopSlow response and rate of change of powerReliability is highly influenced by the mechanical limitations
Steam turbines
There are several models for steam turbines in PSS/E library:
Simplified models: TGOV1, CRCMGV, BBGOV, IEEEG1, TURCZT…more detailed models: TGOV2/3/4/5, WSIEG1
ΣΣ
mediumpressure turbine
turbinepowerbasedon Sn
generator activepower based on Sn
frequency
Ps =steam (throttle) pressure(may be assumed as constantfor stability calculations )
If there exist fast valving,power/load unbalance Relay,acceleration Relay,intercept valves and so on,please give a more detailedmodel see I3I
1
+ -
based on Pn
setpoint
speedcontroller
DeadBand
(if availablewith hysteresisor back slash)
Valve
PsAs
high pressure partVopen
Vclose
1
0 position
area
Electro-hydraulicTransducer
lowpressure turbine
interceptionvalve
boiler
storage
-
Reheater
Dead Band
rate limiter
+
+
FKFKgenerator
speed
measurement
–setpoint
(transducer)(filter)
111
RsT+ 111
RsT+
ΣΣ ΣΣ
ENsT+11
ENsT+11
VT1
VT1
s1s1
ΣΣ
ssT1
ssT1
HPsT+11
HPsT+11
RsT+11
RsT+11
HPKHPK
ΣΣ
MPsT+11
LP
LP
sTK+1 LP
LP
sTK+1
1=++ LPMPHP KKK
ππ
1,0
0
1,0
0
power controller
PI
isT+11
isT+11
PK PK
ΣΣ
fcorK fcorK
reff ΣΣ
[ ]puf
ΣΣefGRP
GP
211
RsT+ 211
RsT+
GP
measurement
n
vϕcos
1=
measurement
n
vϕcos
1=
[ ]puGω
efGRω
– nϕcosTP
steam flowsm&
steam flowsm&
m&
typical values:TR1 = sec 0.02TR2 = sec 0.05-1KP = pu 0-1Ti = sec 10TV = sec 0.1-0.3Vopen = pu/s 0.1...4Vclose = pu/s -0.1...-4KHP = pu 0.25THP = sec 0.27
typical values:TR = sec 5-9KMP = pu 0.25TMP = sec 0.3KLP = pu 0.50TLP = sec 0.7TS = sec 30 - 100Kfcor = pu 20Kf = pu 20 (1/ σ)TEH = sec 0.1 - 2Dead Band = mHz ±5
ππ
ππ
MPK
Steam turbines
Recommendation is to use WSIEG1, since it emphasizes all characteristics of multistage steam turbines for cross compound or tandem compound
Steam turbines
Parameter ranges for WSIEG1
Gas turbines
Primary driving force is the exhaust gas from burned mixture of air and gas in the combustion chamberJet engine technology fixed to the groundControl of power is achieved through control fuel injection and not through flow of working fluid (water or steam)It can be used in Open Cycle (alone) or Combined Cycle (with steam turbines)
Gas turbines
Advantages:High controllability of power generationVery fast rate of power change
drawbacks:Due to the extreme operating conditions, it requires several other control loops (temperature control, NOx control)Installed powers up to 300 MW (for the open cycle)
Gas turbines
There are several models for gas turbines in PSS/E library:
generic models: GAST, WESGOV
more detailed models: GAST2A, GASTWD, GGOV1, URCSCT, URGS3T
Gas turbines
Recommendation is to use GAST, since it emphasizes all characteristics of a single gas turbine
Gas turbines
For a more detailed approach and in case of often actions of temperature control, recommendation is to use GAST2A or GASTWD (which is PID controlled)
Gas turbines
Parameter ranges for GAST
Static droop
Limitations of power are given through the limitation of valve opening
In many cases Dturbcould be ignored
Generic turbine models
In case of absence of any knowledge about the turbine parameters, use IEEEG3 (for Hydro), TGOV1 (for steam) and GAST (for gas) with ADEQUATE parameters (droop, limitations etc).
Thank youThank you