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6-25-07 2007 PES General Meeting 1
Overview of Transmission System Application Requirements for FACTS Controllers
Don Ramey
6-25-07 2007 PES General Meeting 2
Flexible AC Transmission System. FACTS
Evolving technology-based solutions to help electric utilities fully utilize their transmission assets.
Alternating current transmission systems incorporating power electronic-based and other static controllers
6-25-07 2007 PES General Meeting 3
Development of the Special Publication
Working Group 15-05-13 has been meeting since at least January 2000 to prepare this document.
More than 50 engineers have submitted written material or attended meetings.
Both the scope of the document and the pace of commercialization of FACTS Controllers changed several times.
6-25-07 2007 PES General Meeting 4
Outline of the Special Publication
Transmission System Planning Considerations Overview of FACTS Controllers FACTS Controller Models Operational Requirements for FACTS
Controllers
6-25-07 2007 PES General Meeting 5
Transmission System applications for FACTS Controllers
Steady state Voltage regulation and control
Steady state control of power flow on a transmission line
Transient stability enhancement Damping at transmission system
oscillation frequencies (0.2 2 Hz)
6-25-07 2007 PES General Meeting 6
Benefits from steady state Voltage regulation and control
Reduction in transformer tap change operations and shunt capacitor switching
Better voltage profiles for customers System more prepared to withstand
contingencies
6-25-07 2007 PES General Meeting 7
Control VoltageNon FACTS Control Methods
FACTS Controllers
Electric generators Synch. CondensersTransformer tap-changerShunt Capacitor Shunt Reactor
Static Var Compensator (SVC)Static Synchronous Compensator (STATCOM)Superconducting Energy Storage (SMES)Battery Energy Storage System (BESS)
6-25-07 2007 PES General Meeting 8
Benefits of steady state control of power flow on a transmission line
Reduce unscheduled line flow and allow increased contract flow
Control overloads to allow higher system flow
Force current flow in cold weather conditions to prevent ice formation
Force current flow to help control over voltage
6-25-07 2007 PES General Meeting 9
Control Power FlowNon FACTS Control Methods
FACTS Controllers
Generator schedulesTransmission line switchingConventional Phase Angle Regulator (PAR)Series Capacitor HVdc TransmissionInter-phase Power Controller (IPC)
Thyristor controlled Series Capacitor (TCSC)Thyristor controlled Phase Shifter (TCPST)Unified Power Flow Controller (UPFC)Static Synchronous Series Compensator (SSSC)Interline Power Flow Controller (IPFC)
6-25-07 2007 PES General Meeting 10
Benefits of improved transient stability
Allow increased steady state loading Reduce need for load shedding or other
special protection measures Reduce susceptibility for system collapse
from multiple contingency events
6-25-07 2007 PES General Meeting 11
Improve Transient Stability Non FACTS Control Methods
FACTS Products
Braking resistorExcitation Spec. Prot. SystemsFast ValvingIndependent pole trippingLine sectioningHVdc
Thyristor Controlled Braking Resistor (TCBR)Thyristor Controlled Phase Shifting TransformerSVC, STATCOM, TCSC, UPFC, BESS, SMESS, SSSC, IPFC
6-25-07 2007 PES General Meeting 12
Benefits of enhanced dynamic stability
Allow system operation over larger range of loading profiles without power and voltage oscillations
Reduced need for special protection systems
6-25-07 2007 PES General Meeting 13
Enhance Dynamic StabilityNon FACTS Control Methods
FACTS Products
HVdcPower System Stabilizer
TCSCSVCSTATCOMUPFCSSSC
6-25-07 2007 PES General Meeting 14
Reactive power to maintain 1.0 pu V at both ends of a 100 mile long 500 kV transmission line
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
0 1 2 3 4 5
Real Power to load (pu)
R
e
a
c
t
i
v
e
P
o
w
e
r
(
p
u
)Generation endLoad End
1.0 pu = 1000 MVA
6-25-07 2007 PES General Meeting 15
Outline of the Special Publication
Transmission System Planning Considerations Overview of FACTS Controllers FACTS Controller Models Operational Requirements for FACTS
Controllers
6-25-07 2007 PES General Meeting 16
Steady State Models
The SVC has an embedded model in the most widely used power flow (load flow) software. User defined models are often required for other controllers. Can model many of the controller functions
in load flow programs using existing models for non FACTS equipment Models must also be implemented in EMS
software
6-25-07 2007 PES General Meeting 17
Models for Transient and Dynamic System Simulations (Transient Stability and Dynamic Simulation Programs)
Models must be compatible with the simulation tool being used. Power circuit equations solved
algebraically Inverter represented as voltage source Voltage/power change occurs at each
simulation time step Damping control functions represented
with differential equations
6-25-07 2007 PES General Meeting 18
Models for Harmonic Analysis and Detailed Transient Analysis (EMTP)
Models must be supplied by the equipment manufacturer Models must be compatible with
EMTP or EMTDC analysis software Inverter power circuits can be
modeled as voltage sources or by detailed switching circuits
6-25-07 2007 PES General Meeting 19
Outline of the Special Publication
Transmission System Planning Considerations Overview of FACTS Controllers FACTS Controller Models Operational Requirements for FACTS
Controllers
6-25-07 2007 PES General Meeting 20
Operational Robustness Requirements
Control based upon directly measured system dynamics Assured resources for prompt detection,
analysis and correction of anomalous controller effects Performance monitors that communicate
information to system analysts Commissioning and periodic certification tests Information exchange with major grid operators
6-25-07 2007 PES General Meeting 21
Conclusions Transmission planning may be more
difficult in deregulated systems, but functions have not changed FACTS controllers have been designed
and installations placed in operation to perform most of the identified control functions Realization of the full benefits of FACTS
controllers requires many more installations than presently exist.
6-25-07 2007 PES General Meeting 22
Issues that have limited the application of FACTS Controllers
Costs higher than alternatives for many applications Size of power semiconductors needs to increase Semiconductor costs have not decreased as predicted
Transient overload capability not as much as generators or other transmission equipment VSI controllers must be bypassed or blocked for close-
in faults Long term reliability and equipment life not well
established Limited number in service and technology changes
Recommended