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* GT2 EnergiaAv. das Amricas 500 Bloco 15 / Sala 201 Shopping Dowtown, Rio de JaneiroRJ.
CEP 22640-100. e-mail: [email protected]
XII SEPOPE20 a 23 de Maio 2012
May20th
to 23rd
2012RIO DE JANEIRO (RJ) -
BRASIL
XII SIMPSIO DE ESPECIALISTAS EM PLANEJAMENTO DAOPERAO E EXPANSO ELTRICA
XII SYMPOSIUM OF SPECIALISTS IN ELECTRIC OPERATIONAL
AND EXPANSION PLANNING
A synchronous machine and network model for a full-scope fossil-fuel powerplant training simulator
J.I.R. Rodriguez1*; C.D.R. Shirozaki1; V.D. Souquet1; A.L. Spinola1; M.R. da Silva21GT2 Energia
2UTENFBrazil
SUMMARY
An efficient real-time operator training activity can be achieved using a training simulator. An
example of this application is the full-scope power plant simulator. The term full-scope means that theresponses simulated are identical in time and indication to the responses received in the actual plantcontrol room under similar conditions. The complete software contains modules to represent thethermodynamic cycle and the process of electromechanical energy conversion with their respectivecontrols. The use of the modern software engineering techniques allows to design this software as setof software components (mechanical, electrical, etc.) intended to work together to achieve the full-scope requirements.
In this work the current state of the electrical components development to be used in a full-scope
power plant simulator is presented. Initially, a development methodology that belongs to a familycalled Agile Software Development is presented. It has shown to be satisfactory for small teams
working in the development of engineering application in short intervals of times. Using thismethodology, and following the Object Oriented Paradigm, the software architecture is described andthe electrical component is partially implemented. This component uses a service-oriented architectureand considers a linear algebra solver, a network topology processor, a power flow and a modifiedtransient stability modules. The modifications are proposed in the synchronous machine model to
simulate the generator operating in load and in no-load scenarios. The implementation is done usingthe VisSim
TMenvironment and the C++ language. It has been tested for load and no-load scenarios.
Within the tests there are the steady state and transient analysis. The last test uses a third-partycomponent (real representation of the turbine speed control). The numerical results obtained have beensatisfactorily compared against the recorded operational data of a real combined cycle power plant.
KEYWORDS
Power Plant, Training Operator, Synchronous Machine, Distributed Control System.
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1. IntroductionTraining activities, for each staff person responsible for the real-time operation of power systems, arevital to reduce the risk of operational damages and even blackouts [1]. Experience shows that an
efficient learning can only be properly achieved, in short term, using simulators to train operators [2].
These simulators aim to improve the operators skills, which vary according to the control center theywork in. Depending on the type of control center, it can be distinguished in four main simulatorsgroups: for an Independent System Operator / Regional Transmission Organization (ISO/RTO), for ageneration company (Genco), for a transmission company (Transco) and for a load serving entity
(LSE). The main difference between the first group, historically called Operator Training Simulator(OTS) or Dispatcher Training Simulator (DTS), and the last three is that the first simulates the effectsof systemic operational decisions while the others simulate the effects of local operational decisions.These decisions, systemic and local, influence on each other and, when poorly executed, can introducedisturbances outside their field of action.
Within the Genco operator training simulators, based on the type of prime mover installed, thehydropower, the nuclear power plant or the fossil-fuel power plant training simulators (FPTS) can be
distinguished. According to specific training objectives and to end user requirements, the FPTS areclassified as full-scope, reduced-scope or generic. A full-scope FPTS is a high-realism simulator, anexact duplicate of the power plant control room, containing duplicates of actual controls, instruments,panels and indicators. The unit responses simulated on this apparatus are identical in time and theindication to the responses received in the actual plant control room under similar conditions [3]. Themathematical models represent the thermodynamic cycle and the process of electromechanical energyconversion with their respective controls, involving thermal, hydraulic, mechanical and electricaldevices. In these models, it is necessary to do some simplifications to meet real-time simulationrequirements. The electrical simplifications are used to represent the synchronous machine as avoltage source behind transient impedance and to represent the electrical network as an equivalentload [4]. Actually, the great advances in computing (hardware and software) allow the use of moredetailed electrical models increasing the set of phenomena to be represented and even meet the real-
time requirements.The use of modern software engineering techniques enables design a full-scope FPTS as a set ofsoftware components (mechanical, electrical, etc.) intended to work together to represent the majorityof operational procedures of the power plant [5]. This work summarizes the current state of anelectrical software component development for a full-scope FPTS. The component requirements and abrief summary of the development methodology used are presented initially. This methodologybelongs to the group of Agile Software Development [6], which has interactive and incrementalcharacteristics that allows the end user to achieve measurable results in short and fixed times. Next,the actual state of the components designis described. It considers linear algebra solver [7], a networktopology processor [8], a power flow [9] and modified transient stability [10] modules. This lastmodule contains the well-known power flow models for the network (transformers, transmission lines,loads, etc.) and a modified sixth order model to represent the synchronous machine. Somemodifications were done and they intent to simulate the generator operating on load and on no-load.Subsequently the actual software prototype implemented is presented, which contains the power flowcoded in C++ programming language and the modified transient stability (synchronous machine andnetwork models) coded in VisSim
TM[11]. The VisSim
TM is a visual block diagram language for the
simulation of dynamical systems. Its Automatic C Programming Language Code Generation featurehas also allowed the transient stability code to be translated in a high-level programming language.Finally, some numerical results obtained by the software prototype working alone and also with amechanical and control third-party components are presented. The mechanical component consists ofan approximate model for the gas turbine coded in VisSimTM. The control component consists of anapproximate model for the voltage control and an exact replica of the turbine speed control used by areal power plant. The results obtained are compared satisfactorily against the operational and
oscillography data of a real combined-cycle power plant.
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2. Electrical Software RequirementsIn the development of an electrical component for a full-scope FPTS, the main requirements can betranslated in two major challenges: the choices of the electrical models and the strategy of integration
with the other components.
The choice of the devices models is performed with the objective to reproduce the most operatingprocedures of the power plant. For a synchronous machine a stability transient model with smallmodifications meets this objective [12]. Based on this experience, a generators transient model andnetworkssteady-state model (transmission lines, transformers and loads) were selected.
The choice of the integration strategy is made in order to allow continuous components updates withminimal impact as possible. Within updates there are changes mainly in devices models andcomponents technologies, so for an electrical component the Service-Oriented Architecture (SOA)meets this objective [5]. Therefore this architecture was selected in advance.
To deal with the identified requirements complexity, and the inherent unexpected problems in thedevelopment process, a software methodology was adopted.
3. Software Development MethodologySoftware engineering provides a wide range of development methodologies in which two trendsdominate. The first follows a process with a rigid formality and the second sacrifices part of formalityas compensation for rapid and adaptive development. In the first group, one of the best proposals is theRational Unified Process (RUP) [13]. One successful application of RUP, in power system simulation,can be found in [14]. The RUP is a well-defined methodology but its not suitable fordevelopmentwith small teams or in short intervals of time. In these cases the best alternative is to use a
methodology that belongs to the second group, the family Agile Software Development (ASD) [6].
The ASD advocates frequent software releases (prototypes) in short development cycles, which isintended to improve productivity and introduce checkpoints where new customer requirements can beadopted. Each short cycle is called iteration and the basic idea is that further iterations use fully or
partially previous iterations adding new software functionalities or user modified requirements. Theseadditions determine the incremental feature of the methodology. The life-cycle of generic ASD can beshown inFigure 1.Literature shows a wide variety of ASD proposals and they are mostly dedicated tothe development of business and management software, in fact there isnt any specific proposal forengineering application. The main difference between a business and engineering software is that thelast one is strongly dependent on bibliographic research that consumes a large amount of time. Onemethodology that follows the ASD principles with the literature review taken into account can be seeninFigure 2.In this work this methodology has been adopted.
Time
(Weeks)
1 2 z
Iteration 1
A D I T
Iteration 2
A D I T
Iteration z
A D I T
LEGEND
AAnalysis
DDesign
I Implementation
TTest
System Functionality
(Requirements)
Time
(Months)
1 n n+1 n+2 m
Iteration n+1
Literature Review
A D I T
Iteration 1
Literature Review
Iteration n
Literature Review
Iteration n+2
Literature Review
A D I T
Iteration mA D I T
LEGEND
AAnalysis
DDesign
I
ImplementationTTest
System Functionality
(Requirements)
Figure 1: Life-cycle of generic ASD Figure 2: Life-cycle of modified ASD
The definition of each iteration (with their respective requirements) was achieved based on the
intersection of three main axes: first is the size of the modeled power system; second is the complexity(details) of the devices models and third is the level of integration with other components. Each
iteration had an initial estimated time of one month. Twenty iterations were identified: the first six forreview, and the last fourteen for a prototypes building. Future prototypes have greater details related tothe grid, to the devices model or to the integration component than previous one. The Unified
Modeling Language (UML) [15] was selected for documentation.
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4. Software DevelopmentAfter the Literature Review iterations, each Prototype iteration is basically composed by four mainstages: analysis, design, implementation and tests. In this section the cumulative results from the first
12 iterations (for the analysis, design and implementation) are presented. The test results will bepresented in the next section.
In the analysis stage the initial requirements are improved by making a conceptual model in adeveloper language. The analysis model is refined specifying how the prototype will be built to meetthe established requirements in the design stage. The software architecture and the models should bechosen in this stage. In the implementation stage the design model is translated to a programminglanguage.
4.1. AnalysisThe requirements which comprises, in summary form, the interfaces between the electrical(synchronous machine) with mechanical (turbine) and control (AVR, PSS, etc.) components can beseen in Figure 3.They are understandable by the client (power system engineer) and produced an
analysis model in developers language(software engineer). This model is shown inFigure 4.
GENERATOR
Vre
Vim
Pt
Qt
VOEL Overexcitation
Limiter (OEL)
Ifd
Vs EfdAutomatic
Voltage
Regulator
(AVR)VOEL
VREF
VMOD
VUEL
VUEL
Underexcitation
Limiter (UEL)
Id
Iq
Vd
Vq
VMOD
W
Iq
Vd
Id
Vq
Ifd
Pe
Synchronous
MachineEfd
Pm
Vim
Vre Qt
Pt
W
W
Pe
PREFControl Speed
(GOV)
MWc
TurbineMWcPm
W
VSPower System
Stabilizer (PSS)
Pe
22* VimVreV
MOD
Efd
Ifd
Id
Iq
MWc
Pe
Pm
PREF
Pt
Qt
Vd
Vq
Vre
Vim
Vs
VREF
VMOD
VOEL
VUEL
=> Field voltage
=> Field current
=> d-axis current
=> q-axis current
=> Mega-watt controlled
=> Air-gap electrical power
=> Air-gap mechanic power
=> Reference power
=> Apparent power (real)
=> Apparent power (imaginary)
=> d-axis voltage
=> q-axis voltage
=> Terminal voltage (real)
=> Terminal voltage (imaginary)
=> Stabilizer voltage
=> Reference voltage
=> Terminal voltage (module)
=> Over-excitation limits voltage
=> Under-excitation limits voltage
LEGEND
APPLICATION
EPS
ELECTRICAL
MECHANICAL
DCS
Efd, etc.
Ifd, etc.
Pm, etc.
(Machine, etc.)
(Flow, etc.)
Component
Dependency
Class
Inheritance
Association
UML LEGEND
Figure 3: Electrical requirements Figure 4: Analysis model
4.2. DesignThe design model comprises the architecture of the simulator and can be seen in Figure 5. The
ELECTRICAL, GUI (Graphical User Interface), DCS (Distributed Control System) andMECHANICAL components are integrated through the COMMUNICATION component. This lastprovides an array (Shared Memory) with all variables of interest. The service-oriented architecturewas selected [5]. The COMMUNICATION is a service that meets the request of other services(ELECTRICAL, DCS and MECHANICAL) and client (GUI) for read and/or write variable in theShared Memory. Small tests (with services implemented in C#, C++ and Fortran working together) toprove the architecture have been carried out satisfactorily.
The electrical component is composed by other four components: I/O (interface input/output), EPS
(physical power system), MATH (mathematical functionalities) and APPLICATION (electrical
analysis), which is the main component for this paper. In the Figure 6 the class diagram for theAPPLICATION component is shown. Between these classes it can be seen the NTOPOLOGY(Network Topology Processor), FLOW (power flow) and TSTABILITY (Transient Stability). The twolast classes are the main topic for this work, their core is the network model and the synchronousmachine model respectively, and they are commented as follow.
ELECTRICAL::
APPLICATION
ELECTRICAL::
MATH
ELECTRICAL::
I/O
ELECTRICAL::
EPS
ELECTRICAL
GUI
MECHANICAL
DCS
COMMUNICATION
...
...
Generator Voltage (Vt)
Generator Power (Pt)
...
...
...
...
...
...
SHARED MEMORY
MATH::MATH AN ALY SI S N TOP OL OG Y
FLOW TSTABILITYMATH::VISSIM
APPLICATIONMATH
Figure 5: Design model Figure 6: Class diagram
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4.2.1.Network Model
The network was designed to be represented by two coexisting models. The first describes the network
connectivity in terms of bus-sections and switching-devices (physical model) and is used primarily asa repository of existing devices. The second describes the network in terms of busses and branches(logical model) and is targeted for use in some kind of power system analysis. A Network Topology
Processing (NTP) is responsible for transforming the network from physical to logical model. TheNTP was designed as a class NTOPOLOGY and basically replaces the switching devices by zero orinfinite impedances depending on their states being closed or open respectively. In the process thebusses and their groups (electrical islands) are identified. This process can be shown inFigure 7.One
of the best works about the uses of the NTP is [16].
MAIN ELECTRICAL
GRID
BUS-SECTION 3962
BUS-SECTION 3961
BUS-SECTION 3960
BUS 3962
BUS 3961
BUS 3960
NODE 04
NODE 02
NODE 01
NODE 03
NODE 06 NODE 07
NODE 08
NODE 05
NODE 09NODE 11
NODE 10NODE 12NODE 13
BUS 02
BUS 01
Isle 01
Substation
MAIN ELECTRICAL
GRID
BUS 3961
BUS 3960
BUS 01
Isle 01
MAIN ELECTRICAL
GRID
PHYSICAL MODEL NETWORK TOPOLOGY PROCESSING LOGICAL MODEL
Figure 7: Network Topology Processing
The class FLOW was designed following the Object Oriented Paradigm (OOP) [17] providing a set ofsteady-state models. Among these models there are the well-known VT, PV and PQ for generators, PIfor lines and transformers and PQ and ZIP for loads [9]. These models can be shown inFigure 8 andthey generally calculate the terminal active and reactive power (Pk, Qk) considering the terminal
voltage module (Vk) and angle (Tk ork) known. The overall analysis constitutes a non-linear problemsolved by the Newton- Raphson technique.
NAME PARAMETERS
GENERATOR
PkQk
VkTkVT
esp
k VV
esp
k
?, kkQP
PkQk
VkTkPV
esp
k PPesp
k VV
?, kkQ
PkQk
VkTkPQ
esp
k PP
esp
k QQ
?, kkV
espespV ,
espespVP ,
espespQP ,
NAME PARAMETERS
LOAD
PkQk
VkTkPcte
esp
k PP 0
esp
k QQ 0
?, kkV
Pk,Qk
VkTk
Icte
kesp
k VPP 0
kesp
k VQQ 0
?, kkV
VkTk
Zcte
I = cte
yy = cte
20 kesp
k VPP
20 kesp
k VQQ
?, kkV
Pk,Qk
espesp QP00
,
espesp QP00
,
espespQP
00 ,
NAME CIRCUIT / EQUATIONS PARAMETERS
TRANSMISSION LINE
VkTk
PIPkm
Qkm
shkmkm bbg ,,
VmTm
gkm+jbkm
Pmk
Qmk
TransmissionLine
kmkmkmkmmkkmkkm SenbCosgVVgVP 2
kmkmkmkmmkshkmkkm CosbSengVVbbVQ )()( 2
jbsh jbsh
NAME CIRCUIT / EQUATIONS PARAMETERS
TRANSFORMER
VkTk
PIPkm
Qkm
abg kmkm ,,
VmTm
aykm
Pmk
Qmk
Transformer
kmkmkmkmmkkmkkm SenbCosgVaVgaVP 2
kmkmkmkmmkkmkkm CosbSengVaVbaVQ )()( 2
a(a-1)ykm
(1-a)ykm
CIRCUIT / EQUATIONS CIRCUIT / EQUATIONS
LEGEND
espV
a
kmb
kP
kmP
kmg
kQ
esp
k
espP
0
kV
km
shb
esp
kP
mkP
kmQ
mkQ
mV
espQ
0
espQ
kT
mT
: Tap (p.u.)
: Susceptance k-m
: Shunt susceptance
: Specified angle voltage
: Angle voltage (node k)
: Angle voltage k-m
: Series conductance k-m
: Initial specified active power
: Specified active power (node k)
: Calculated active power (node k)
: Calculated active power k-m
: Calculated active power m-k
: Initial specified reactive power
: Specified reactive power
: Specified reactive power
: Calculated reactive power k-m
: Calculated reactive power m-k
: Specified module voltage
: Module voltage (node k)
: Module voltage (node m)
: Angle voltage (node k)
: Angle voltage (node m)
Figure 8: Devices steady-state models
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4.2.2.Synchronous Machine Model
The class TSTABILITY reuses all steady-state models from FLOW with the exception of generator.
In electrical point of view, such as shown inFigure 3,the generator model is mainly composed by thesynchronous machine model, which is composed by two sub-models. The first (MAIN) is responsiblefor the algebraic / differential equations that determine the behavior transient of the device. The
second (IC) is responsible by the calculus of the state variables initial conditions.Main Equation (MAIN)
The synchronous machine model was obtained from [18] but was originally presented in [19] and isformally known as MD03 model. The equations for this model are shown, in block diagram form, inFigure 9.This model has mainly four inputs: the terminal voltage real (Vre) and imaginary (Vim) part,the field voltage (Efd) and the turbine power (Pm); and four outputs: the apparent power real (Pt)andimaginary (Qt) part, and the current real (Ire)and imaginary (Iim) part. This model is composed by sixsub-models: an interface for generator to machine, an interface for machine to generator, the q-axisequations, the d-axis equations, the electrical equations and the swing equation. All magnitudes andparameters are in p.u. values in the generator base (Apparent Power base and Voltage base). Thismodel can be used for the generator simulation in load and no-load scenarios. In the no-load scenarios
two equations have to be added: the d-axis and q-axis currents (Id,Iq) equals to zero.
ADD
+
- @Elq
INPT
Efd ADD
+
-
-
Pace
ADD
+
+
w-wo
GAIN
InOutDD*(w-wo)
w0
ADD
+
+
+
Pe
ADD
+
-
+
Idl
ADD
-
+
-
Iql
OUTP
Ifd
q
dT delt*
DQ-C
d
q
delt
Im
ReEre
Eim
Vd
Vq
INPT
delt
OUTP
delt
INPT
delt
OutInEld
s
1/Tlqo
INTG
ADD
-
-
+
EdsINPT
Id
INPT
Iq
OUTP
Id
OUTP
Iq
OutInwEllq
s
1/Tlldo
INTG
ADD
-
-
+
@Ellq
GAIN
In Out-1
ADD
+
-
+
Qe
OUTP
Vd
OUTP
Vq
INPT
Vd
INPT
Vq
MOD2
Re
22ImRe
Im
[i]2
GAIN
In Outr r*[I]2
GAIN
In Outxlld-XlE2d
ADD
-
+
+
Eqs
ADD
-
+
+
@ElldOutIn
wElld
s
1/Tllqo
INTG
ADD+
+
Elld
ADD+
+
Ellq
OUTP
Pe
OUTP
Qe
OUTP
Elld
OUTP
Ellq
INPT
Elld
INPT
Ellq
OutInElq
s
1/Tldo
INTGGAIN
In Out(xd-xld)
(xld-Xl)
Eq_
ADD
-
- @Eld
ADD
+
+ Eq
SWING EQUATION
D-AXIS EQUATION
Q-AXIS EQUATION
MACHINE TO GENERATOR
ELECTRICAL EQUATION
OUTP
Pt
OUTP
Qt
INPT
Id
INPT
Iq
OUTP
w
ADD-
+
Itre
ADD+
-
Itim
GAIN
In Out-1Iim*
OUTP
Iim
OUTP
Ire
GAIN
In Outxld-xlldId*()
GAIN
In Out(xlld-Xl)
(xld-Xl)
E1d
GAIN
In Out(xd-Xl)
(xd-xld)
E3d
GAIN
In Out1__
(xd-Xl)
Ifd
GAIN
In Out1_
xlld
Id
GAIN
In Outxllq-XlE2q
GAIN
In Out-1
GAIN
In Out(xq-xlq)
(xlq-Xl)
Ed_
GAIN
In Outxlq-xllqIq*()
GAIN
In Out(xllq-Xl)
(xlq-Xl)
E1q
GAIN
In Out(xq-Xl)
(xq-xlq)
E3q
GAIN
In Out1_
xllq
Iq
INPT
Pm
OutIns
376,99
INTG
delt
MULT
In
OutVq*Iq
In
MULT
In
OutVd*Id
In
MULT
In
OutVd*Iq
In
MULT
In
OutVq*Id
In
INPT
Vre
INPT
Vim
INPT
Vq
GAIN
In OutrIq*r
GAIN
In OutrId*r
INPT
Vd
INPT
WO
INPT
Pe
GENERATOR TO MACHINE
INPT
Vre
INPT
Vim
CONS
-0.5*(xllq+xlld)/
(r*r+xlld*xllq)
Bmq
CONS
r/(r*r+xlld*xllq)Gmq
OutIns
1/2H
INTG
w-wo
CONS
0
CONS
0
d
q
delt
Im
Re
C-DQ
Im
ReT
delt*
reA
imA
reB
imB
Re
Im
CMUL
Ire1
Iim1BA*
H
D
units
r
xd
xq
Xl
xld
xlq
xlld
xllq
Tldo
Tlqo
Tlldo
Tllqo
=> Inertia constant of rotor equivalent (MW.s/MVA)
=> Mechanical damping of rotor equivalent (pu torque/pu)
=> Number of units of machine equivalent ( )
=> Stator resistance (pu)
=> d-axis synchronous reactance (pu)
=> q-axis synchronous reactance (pu)
=> Leakage reactance (pu)
=> d-axis transient reactance (pu)
=> q-axis transient reactance (pu)
=> d-axis subtransient reactance (pu)
=> q-axis subtransient reactance (pu)
=> d-axis transient time constant in open circuit (seg)
=> q-axis transient time constant in open circuit (seg)
=> d-axis subtransient time constant in open circuit (seg)
=> q-axis subtransient time constant in open circuit (seg)
PARAMETERS
INPT
Vre
INPT
Vim
INPT
Efd
OUTP
Pt
OUTP
Qt
OUTP
Iim
OUTP
Ire
INPT
Pm
reA
imA
reB
imB
Re
Im
CMUL
Ire2
Iim2BA*
reA
imA
reB
imB
Re
Im
CMUL
Pt
QtBA*
Figure 9: Synchronous machine MAIN model
I nitial Condition (IC)
In the synchronous machine model, each Integrator Block (INTG) needs an initial condition. Astrategy for the calculation of these values is described below. Two auxiliary variables are adding in
the model for each INTG, one for the input (dx0) and other for the output (x0) of this block. It may benoted that dx0is the derivative ofx0and in the first integration stepx0is the INTGs initial condition.All these auxiliary variables are grouped in a new sub-model called Initial Condition. In this sub-model a new equation is added by each INTG: dx0 equal to zero (x0, unknown). All these newequations are valid only for the first integration step. The new sub-model described works togetherwith the other machines sub-models, which are calculating their initial condition values in a genericmanner. For efficiency reasons this sub-model could be replaced by other customized for a particularmain model or another that sets the initial values to constants filled manually. In analogous manner,this model can also be used if any main models input is unknown, since that for each unknown inputone main models output mustbe known.
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5. Test ResultsNumerical results of the methodology, applied to the UTE Norte Fluminense (UTENF), are shown anddescribed in this section. Twelve iterations were worked out during the project and three of them; due
their representative results for this work, were selected for this presentation. Each iteration lasted onemonth and reuses partially or wholly the previous iterations products. The first one corresponds to a
steady-state analysis of the UTEs main electrical system. The second and third iterations correspondto a transient analysis of one of generators connected and disconnected from the grid respectively. Thecomparison of the Data Simulated with the UTEs Data Plant is shownfor each iteration.
5.1. Steady-State ScenarioIn this iteration the steady-state models of the devices that operates at voltages greater than or equal to15 kV were tested. InFigure 12 a) the electrical system simulated is shown. In this system there are
two substations connected by two transmission lines. In the first substation, owned by UTE, there arefour generating units (three operating with a gas turbine and one with a steam turbine) each oneconnected to a double-busbar through a power transformer. In the second substation, owned byFURNAS, there is a double-busbar that represents the rest of the Brazilian Grid. For this simulation,the switching devices were replaced by zero or infinite impedances depending on their states closed oropen respectively. InFigure 12b) the deviation (error)between the UTEs Plant Data and SimulationData can be seen. The error is separated by: (i) electrical devices: transmission lines, transformers and
generators; and (ii) electrical magnitudes: Voltage (V), Current (A), Active Power (MW) and ReactivePower (MVAr).
345 kVBARRA B BR8A
345 kVBARRA A BR8B
345 kV
BARRA B
ACC10
345 kV
BARRA B
ACC20
LT-1LT-2
TRS TR1TR2TR3
TS1
13BAC12
13BAC11 12BAC11
12BAC12 11BAC12
13BAC13
11BAC11
12BAC13 11BAC13
ACE74
ACE70
ACE73
ACE64
ACE60
ACE63
ACE76 ACE66
ACE71
ACE72
ACE61
ACE62
ACE51
ACE52
ACE41
ACE42
ACE21
ACE22
ACE53
ACD50
ACE54
ACE56
ACE55
ACE43
ACD40
ACE44
ACE46
ACE45
ACE23
ACD20
ACE24
ACE26
ACE25
ACE13
ACD10
ACE14
ACE15
ACE83
ACE82
ACD80
ACE81
ACE03
ACE02
ACD00
ACE01
ACE92
ACD90
ACE91
ACE04 ACEB4
ACE11
ACE12
TG3 TG2 TG1
6 96 4. 9 AFASEA
6 96 4. 9 AFASEB
6977.1 AFASEC
23.1 KVAB
2 3. 1 K VBC
23.1 KVCA
2 74 .8 M W
-55.3 MVAR
AFASEA
AFASEB
AFASEC
KVAB
KVBC
KVCA
462.8
465.4
462.2
354.5
355.2
355.6
A
A
FASEA
A
A
FASEB
AFASEC
663.4
KVBC
356.7
647.2
KVCA
-386.9 MW
132.5
355.2
MVAR
FASEA
FASEB
FASEC
354.5
667.6
KVAB
KV
354.9 KV
KV
MVAR
MW
0.0 KVBC
0.0 KVCA
0.0 HZ
0.0 KVAB
354.3 KVBC
356.8 KVCA
5 9. 9 HZ
353.8 KVAB
A
BC
CA
AB 355.5
629.0
636.0
648.0
355.4
373.6
-140.4
2 76 .5 M W
-84.8 MVAR
ACD30
ACE32
ACE16
Bus-section
Node
Switch Dev.
Generator
Transformer
Line
Load
LEGEND
A
A
FASEA
FASEB
FASEC
KV
355.2 KV
KV
MVAR
MW
A
BC
CA
AB 355.0
671.4
668.4
658.6
354.5
386.4
-147.3
AFASEA
AFASEB
AFASEC
636.2
KVBC
356.2
640.8
KVCA
-374.0 MW
126.3
357.1
MVAR
355.3
627.0
KVAB
AFASEA
AFASEB
AFASEC
KVAB
KVBC
KVCA
283.2
284.9
284.1
353.7
354.7
355.9
1 63 .7 M W
-63.5 MVAR
AFASEA
AFASEB
AFASEC
KVAB
KVBC
KVCA
276.4
275.8
277.0
353.8
354.4
355.4
1 60 .7 M W
-62.5 MVAR
AFASEA
AFASEB
AFASEC
KVAB
KVBC
KVCA
273.0
272.6
274.8
352.5
352.9
355.5
1 58 .4 M W
-62.9 MVAR
6 64 6. 9 AFASEA
6 66 5. 3 AFASEB
6668.3 AFASEC
14.9 KVAB
1 4. 9 K VBC
15.0 KVCA
1 66 .5 M W
-44.9 MVAR
6 49 7. 3 AFASEA
6 51 5. 6 AFASEB
6518.7 AFASEC
15.0 KVAB
1 5. 0 K VBC
15.0 KVCA
1 64 .5 M W
- 42 .4 M VA R
6 51 8. 7 AFASEA
6 54 0. 0 AFASEB
6527.8 AFASEC
15.0 KVAB
1 5. 0 K VBC
15.0 KVCA
1 64 .7 M W
- 41 .9 M VA R
(a) Electrical system (b) ErrorFigure 12: Steady-State simulation results
LT2 - T
LT2 - F
LT1 - T
LT1 - F
0
2
4
6
8
10
VA
MWMVAr
Error(%)
Magnitudes
Transmission Lines
TRS
TR3
TR2
TR1
0
2
4
6
8
10
VA
MWMVAr
Error(%)
Magnitudes
Transformers
TS1
TG3
TG2
TG1
0
2
4
6
8
10
VA
MWMVAr
Error(%)
Magnitudes
Generators
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The Plant Data were obtained from UTEs three-phase operational database. The Simulation Data wascalculated by a power flow application and the models used are the well-known steady-state models[9]. The models parameters values used were obtained from UTEs documentsand the double-busbarin the Furnas substation was modeled as an infinite bus. The deviation (error) presented wascalculated using the Equation(1). Since the maximum error allowed for one training simulator powerplant is 20% [3], the steady-state models (with their selected value parameters) are considered, apriori, validated. These results can be further improved with the use of a more detailed load model.
%100*)(
max
Pi
sPi
x
xxabsE (1)
E Error (V, A, MW, MVAr)xPi Plant Data in the Phase i (a, b, c).xS Simulation Data.
5.2. Transient Load Scenario - GOV Fast Ramp (13.4 MW/min)In this iteration one transient generator model when operating connected to the grid network wastested. The last iterations electrical system was simplified and was used. This system considered onegenerator operating with a gas turbine (TG1), the transformer connected to it (TR1) and the loadcorresponding to auxiliary services. The UTEs double-busbar was modeled as infinite bus and theload and transformer were represented by their steady-state models. The generator model wascomposed by a synchronous machine model, an approximated Automatic Voltage Regulator (AVR)model, an approximated gas turbine model and an exact replica of the UTENF turbine speed control(Governor). The synchronous machine model was described in the previous section 4.2.2. InFigure 13the Governor structure model is shown.Figure 14 andFigure 17 shown the turbine model and theAVR model used respectively.
Figure 13: Turbine speed control model Figure 14: Turbine model
The practice test had two parts. Initially when the generator is operating at 90% of its nominal activepower (Pt = 162 MW), a signal input of -13.4 MW/min was applied at the Governor making thegenerator to operate at 50% of its nominal power (Pt= 90 MW). Finally, after a few minutes thereverse process was performed. The Simulation Data was calculated by a transient stability applicationusing a trapezoidal technique and integration step of 1 millisecond. The results are inFigure 15 andshow the validation of the models. As can be seen, the model developed for this case responded with agood accuracy in comparison to the plant behavior. The fact that the simulated data does not exhibitany oscillation in the first two minutes validates the implementation of the sub-model IC (initial
condition). These results can be further improved with the use of a more detailed turbines model.
(a) Generator reference active power (b) Generator terminal active powerFigure 15: Plots for a turbine GOV fast ramp (13.4 MW/min).
Tb Speed
MWTarget
SelectedMW
MW/MIN
i10
i20
MWController
d10
d20
TURBINE
SPEED
CONTROL
:MWc
:imw20
:imw10:dmw20
:dmw10
:Pref
:Pe
:w 3600
::Sbase
-13.4
:MWmin
SPEED CONTROL (GOV)
:d10
:i10
X(s)
i10
Y(s)
d10
K2
-------
1+sTv
X(s)
i10
Y(s)
d10
1
-------
1+sTe
:i20
:d20
:i10
:i20
:d10
:d20
:Pm
:Pm:MWc
:MWc
::K2
::Tv
2.1
0.5
0.59 ::Te
PARAMETERSTURBINEMWc
i10
i20
Pm
d10
d20
80
100
120
140
160
0 5 10 15 20 25
Power(MW)
Time (min)
Gen. Reference Power (Pref)
Simulation
Plant Data
80
100
120
140
160
0 5 10 15 20 25
Power(MW)
Time (min)
Gen. Terminal Active Power (Pt)
Simulation
Plant Data
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5.3. Transient No-load Scenario - AVR Reference Step (5% p.u.)In this iteration one transient generator model when operating disconnected to the grid network wastested. This system considered one generator operating with a gas turbine (TG1). The last iterationsgenerator model was modified and used. These changes correspond to the addition of two equations inthe model of the synchronous machine (the currents in the d-axis and q-axis equals to zero). In no-load
scenarios the synchronous machine voltage terminal (Vt) is calculated in function of the current field(Ifd) following the relation existing in the generators Open Circuit Characteristic curve (OCC). In thispaper the effects of magnetic saturation in the air-gap are disregarding making the relation between theVtandIfd, linear.Figure 16 shown this relation.
Figure 16: Generator OCC curve Figure 17: AVR model
The practice test consisted of applying a step of 5% to AVRs signal Vref(Voltage Reference) at timet =1.0 second with a duration of 9.5 seconds. The AVR model used is shown inFigure 17.The results
are inFigure 18 and show the validation of the models. None of the errors, except those correspondingto the times in which events are applied, exceed 5%. These results could be further improved with theinclusion of the limiter blocks in the AVRs model and the saturation effects in the synchronousmachines model.
(a) Generator field voltage (b) Generator terminal voltage
Figure 18: Plots for a generator AVR reference step (5% p.u.)
6. ConclusionsA development methodology and electrical engine prototype component for a full-scope fossil-fuelpower plant training simulator was presented. The methodology has interactive and incrementalfeatures and has shown adequate in the electrical software development in the last year. The prototypeimplemented includes a power flow and a modified transient stability application in a Service-Oriented Architecture.
The power flow has been implemented following the Object-Oriented Paradigm using the C++language. The modified transient stability is implemented using the Visual Block Diagram Language,VisSimTM. The main modification lies in the synchronous machine model, which has been shown valid
for both load and no-load generator scenarios, and has a generic sub-model for initial conditioncalculation. The Automatic C Programming Language Code Generation VisSim
TMfeature has allowed
the transient stability to be fully implemented in a high-level programming language with a time-saving relationship by 10 times.
0
5
10
15
20
0 500 1000 1500 2000V
t:TerminalVoltage(kV)
Ifd: Field Current (A)
Open Circuit Characteristics
Real OCC
675 760
+
-:Vmod
:Vref
:Vref
:Vmod
:Efd
:Efd
+
+X(s)
i10
Y(s)
d10
Ka
-------
1+sTb
:d20
:i10
:d10
X(s)
i10
Y(s)
d10
KIA
----
s
:i20
:d10
:i10
:i20 :d20
::Ka
::Tb
40
0.05
0.1 ::KIA
PARAMETERSAVRVref
Vt
i10
i20
Efd
d10
d20
0,00
0,20
0,40
0,60
0,80
0 5 10 15
Voltage(pu)
Time (s)
Gen. Field Voltage (Efd)
Simulation
Plant Data
0,90
0,95
1,00
1,05
1,10
0 5 10 15
Voltage(pu)
Time (s)
Gen. Terminal Voltage (Vmod)
Simulation
Plant Data
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ACKNOWLEDGMENTThis work has been supported by a discretionary grant from the Research and Development program(P&D) of Usina Termeltrica Norte Fluminense (UTENF) / Agncia Nacional de Energia Eltrica
(ANEEL), Brazil. We would like to thank all the staff of the UTENF for the provision of operationaldata and helpful comments.
BIBLIOGRAPHY
[1] B. Liscouski and W.J.S. Elliott (U.S.-Canada Power System Outage Task Force), Final reporton the August 14, 2003 Blackout in the United States and Canada: Causes andrecommendations,April 2004.
[2] G. Krost, S. Allamby, and P. Lehtonen, Organization and justification of power systemoperators training, WG 39.03; CIGRE SC 39 Session; Paris, 2000.
[3] ANSI/ISAS77.201993, Fossil fuel power plant simulatorsFunctional requirements, May1994.
[4] TRAX International, http://www.traxintl.com/simulator-systems/simulation-software, visitedon 2011.
[5] J.I.R. Rodriguez, A framework proposal for software development for electrical powersystems, Masters thesis, National University of Engineering (UNI), Lima Peru, 2007. (InSpanish).
[6] Manifesto for Agile Software Development, http://agilemanifesto.org/, visited on 2011.[7] L.R. de Araujo, Aplicao de tcnicas de modelagem orientada a objetos a sistemas lineares
esparsos, Dissertao de mestrado, Universidade Federal de Juiz de Fora (UFJF), Juiz de ForaBrasil, 2000.
[8] A.M. Sasson, S.T. Ehrmann, P. Lynch, and L.S. Van Slyck,, Automaticpower system networktopology determination; IEEE Transactions on Power Apparatus and Systems, Vol. PAS-92No. 2, 1973.
[9] A.J. Monticelli, Fluxo de carga em redes de energia eltrica, Edgard Blcher Ltda., 1993
[10] P. Kundur, N.J. Balu and M.G. Lauby, Power system stability and control, McGraw-Hill,1994.[11] Visual Solutions Inc., VisSim Users Guide Version 8.0, 2010.
[12] J.M. Garca-Garca, A generic synchronous machine model for real time training simulators,Proceedings of IEEE Energy Conversion Congress and Exposition, AtlantaUSA, Sept. 2010,pp. 3569-3575.
[13] G. Booch, J. Rumbaugh and I. Jacobson, The Unified Software Development Process,Addison Wesley, 1999
[14] J.J.R. de Oliveira et al., Treinamento e certificao de operadores no sistema SAGEempregando o simulador EPRI/OTS, XI ERIAC, 2005, pp. 1-6.
[15] G. Booch, J. Rumbaugh and I. Jacobson, The Unified Modeling Language: User Guide,Addison Wesley, 1998.
[16] A. Manzoni, Desenvolvimento de um sistema computacional orientado a objetos para sistemaseltricos de potncia: Aplicao a simulao rpida e anlise da estabilidade de tenso, Tese dedoutorado, COPPE/UFRJ, Rio de Janeiro - Brasil, 2005
[17] A. D. Taylor, Object Technology A Management Guide, Addison Wesley, 1997. [18] UTE Norte Fluminense, Relatrio de ensaios da central geradora termeltrica UTE Norte
Fluminense para a unidade geradora a gs no. 1, Fevereiro 2004[19] CEPEL, Programa de Anlise de Transitrios Eletromecnicos. Verso V09-12/01. Manual do
Usurio. Dezembro 2001.[20] LAPACKLinear Algebra PACKage, http://www.netlib.org/lapack/, visited on 2011.[21] SPOOLES Sparse Object Oriented Linear Equation Solver, http://www.netlib.org/linalg/
spooles/spooles.2.2.html, visited on 2011.
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