1. Paulo F. Ribeiro, BSEE, MBA, PHD, PE
Lecture 3
Advanced FACTS Devices and Applications: Performance, Power Quality and Cost Considerations
Paulo F. Ribeiro, BSEE, MBA, PHD, PE
CALVIN COLLEGE
Engineering Department
Grand Rapids, MI 49546

2. FACTS
The Concept
History / Background - Origin of FACTS, Opportunities, Trends
System Architectures and Limitations
Power Flow Control on AC Systems
Application Studies and Implementation
Basic Switching Devices
Conditioners: SVC, STATCOM, TCSC, UPFC, SMES
Specification, Cost Considerations and Technology Trends
Impact of FACTS in interconnected networks
Market Assessment, Deregulation and Predictions

3. The Concept

4. The Concept and Challenges
A transmission system can carry power up to its thermal loading limits. But in practice the system has the following constraints:
-Transmission stability limits
-Voltage limits
-Loop flows
Transmission stability limits: limits of transmittable power with which a transmission system can ride through major faults in the system with its power transmission capability intact.
Voltage limits: limits of power transmission where the system voltage can be kept within permitted deviations from nominal.
Loop flows can be a problem as they are governed by the laws of nature which may not be coincident with the contracted path. This means that power which is to be sent from point ”A” to point ”B” in a grid will not necessarily take the shortest, direct route, but will go uncontrolled and fan out to take unwanted paths available in the grid.

5. The Concept FACTS devices
FACTS are designed to remove such constraints and to meet planners´, investors´ and operators´ goals without their having to undertake major system additions. This offers ways of attaining an increase of power transmission capacity at optimum conditions, i.e. at maximum availability, minimum transmission losses, and minimum environmental impact. Plus, of course, at minimum investment cost and time expenditure.
The term ”FACTS” covers several power electronics based systems used for AC power transmission. Given the nature of power electronics equipment, FACTS solutions will be particularly justifiable in applications requiring one or more of the following qualities:
-Rapid dynamic response
-Ability for frequent variations in output
-Smoothly adjustable output.
Important applications in power transmission involving FACTS and Power Quality devices: SVC (Static Var Compensators), Fixed * as well as Thyristor-Controlled Series Capacitors (TCSC) and Statcom. Still others are PST (Phase-shifting Transformers), IPC (Interphase Power Controllers), UPFC (Universal Power Flow Controllers), and DVR (Dynamic Voltage Restorers).

6. History, Concepts, Background, and Issues
Origin of FACTS
-Oil Embargo of 1974 and 1979
-Environmental Movement
-Magnetic Field Concerns
-Permit to build new transmission lines
-HVDC and SVCs
-EPRI FACTS Initiative (1988)
-Increase AC Power Transfer (GE and DOE Papers)
-The Need for Power semiconductors
Why we need transmission interconnection
-Pool power plants and load centers to minimize generation cost
-Important in a deregulated environment
Opportunities for FACTS
Increase power transfer capacity
SVC (Nebraska GE 1974, Minnesota Westinghouse 1975, Brazil Siemens 1985)
TCSC, UPFC AEP 1999
Trends
-Generation is not being built
-Power sales/purchases are being

7. System Architectures and Limitations
Radial, interconnected areas, complex network
Power Flow in an AC System
Power Flow in Parallel and Meshed Paths
Transmission Limitations
Steady-State (angular stability, thermal limits, voltage limits)
Stability Issues (transient, dynamic, voltage and SSR)
System Issues (Post contingency conditions, loop flows, short-circuit levels)
Power Flow and Dynamic Stability Considerations
Controllable Parameters
Basic FACTS Devices - Impact of Energy Storage

8. Power Flow Control on AC Systems
Radial
Parallel
Meshed
Power Flow in Parallel Paths
Power Flow in a Meshed Systems
What limits the loading capability?
Power Flow and Dynamic Considerations

9. Power Flow Control on AC Systems
50% Series Compensation
Relative Importance of Controllable Parameters
Control of X can provide current control
When angle is large X can provide power control
Injecting voltage in series and perpendicular to the current flow, can increase or decrease

10. FACTS Applications and Implementations
Transmission Transfer Capacity Enhancement
Steady State
Issues
Voltage Limits
Thermal Limits
Angular Stability Limits
Loop Flows
Dynamic
Issues
Transient Stability
Damping Power Swings
Post-Contingency Voltage Control
Voltage Stability
Subsynchronous Res.
Traditional Solutions
Breaking Resistors Load Shedding
Advanced Solutions
FACTS
Energy Storage
Fixed Compensation
Transmission Link
Enhanced Power Transfer and Stability
Line Reconfiguration
Better Protection
SVC
STATCOM
TCSC, SSSC
UPFC
FACTS
Devices
Increased Inertia

11. FACTS Devices Shunt Connected Static VAR Compensator (SVC)
Static Synchronous Compensator (STATCOM)
Static Synchronous Generator - SSG
Battery Energy Storage System (BESS)
Superconducting Magnetic Energy Storage (SMES)
Combined Series and Series-Shunt Connected
Static Synchronous Series Controllers (SSSC)
Thyristor Controlled Phase-Shifting Transformer or
Phase Angle Regulator (PAR)
Interline Power Flow Controller (IPFC)
Thyristor Controlled Series Capacitor (TCSC)
Unified Power Flow Controller (UPFC)
Relative Importance of Different Types of Controllers
Shunt, Shunt-Series
Energy Storage
Energy Storage

12. Power Electronics - Semiconductor Devices
Diodes
Transistors
IGBT
Thyristors
SCR, GTO, MTO, ETO, GCT, IGCT, MCT
Devices
Diode (pn Junction)
Silicon Controlled Rectifier (SCR)
Gate Turn-Off Thyristor (GTO) GE
MOS Turn-Off Thyristor (MTO) SPCO
Emitter Turn-Off Thyristor (ETO) Virginia Tech
Integrated Gate-Commutated Thyristor (IGCT) Mitsubishi, ABB
MOS-Controlled Thyristor (MCT) Victor Temple
Insulated Gate Bipolar Transistor (IGBT)

13. Power Electronics - Semiconductor Devices
Principal Characteristics
Voltage and Current
Losses and Speed of Switching
Speed of Switching
Switching Losses
Gate-driver power and energy requirements
Parameter Trade-off
Power requirements for the gate
di/dt and dv/dt capability
turn-on and turn-off time
Uniformity
Quality of silicon wafers
IGBT has pushed out the conventional GTO as IGBTs ratings go up.
IGBTs - Low-switching losses, fast switching, current-limiting capability
GTOs - large gate-drive requirements, slow-switching, high-switching losses
IGBTs (higher forward voltage drop)

14. Power Electronics - Semiconductor Devices
Decision-Making Matrix

15. AC Transmission Fundamentals (Series Compensation)
P&Q I X
Changes in X will increase or decrease real power flow for a fixed angle or change angle for a fixed power flow. Alternatively, the reactive power flow will change with the change of X. Adjustments on the bus voltage have little impact on the real power flow. Vc Vx I
P1 = E1 . E2 . sin () / (X - Xc) Vr Vs
Vseff = Vs + Vc
Real Power Angle Curve
Xeff = X - Xc Vx Vc
Power Transfer
Vxo Vr Vs
Vseff I
Phase Angle

16. AC Transmission Fundamentals (Voltage-Series and Shunt Comp.)
P&Q I X P E1 E2 I
E1 - E2
Injected Voltage
Integrated voltage series injection and bus voltage regulation (unified) will directly increase or decrease real and reactive power flow.

17. Improvement of Transient Stability With FACTS Compensation
AC Transmission Fundamentals (Stability Margin)
Improvement of Transient Stability With FACTS Compensation
Equal Area Criteria
Q / V 1 2 3
crit A1 A2
Amargin
Maximum Power Transfer
Phase Angle
no compensation
with VAR compensation (ideal midpoint)
1 - prior to fault
A1 = Acceleration Energy
A2 = Deceleration Energy
2 - fault cleared
Therefore, FACTS compensation can increase
power transfer without reducing the stability margin
3 - equal area
3 >crit - loss of synchronism

18. Voltage Source Vs. Current Source Converters

19. Voltage Source Converters

20. Voltage Source Converters
Basic 6-Pulse, 2-level, Voltage-Source Converter

21. Voltage Source Converters
2, 3, 5-level, VSC Waveforms

22. Voltage Source Converters
Output voltage control of a two-level VSC

23. FACTS Technology - Possible Benefits
Control of power flow as ordered. Increase the loading capability of lines to their thermal capabilities, including short term and seasonal.
Increase the system security through raising the transient stability limit, limiting short-circuit currents and overloads, managing cascading blackouts and damping electromechanical oscillations of power systems and machines.
Provide secure tie lines connections to neighboring utilities and regions thereby decreasing overall generation reserve requirements on both sides.
Provide greater flexibility in siting new generation.
Reduce reactive power flows, thus allowing the lines to carry more active power.
Reduce loop flows.
Increase utilization of lowest cost generation.

24. FACTS and HVDC: Complimentary Solutions
Independent frequency and control
Lower line costs
Power control, voltage control,
stability control
FACTS
Power control, voltage control,
stability control
Installed Costs (millions of dollars)
Throughput MW HVDC 2 Terminals FACTS
2000 MW $ M $ 5-10 M
500 MW $ M $ 10-20M
1000 MW $ M $ 20-30M
2000 MW $ M $ 30-50M
(*)Hingorani/Gyugyi

25. FACTS and HVDC: Complimentary Solutions
HVDC Projects: Applications
Submarine cable
Long distance overhead transmission
Underground Transmission
Connecting AC systems of different or incompatible frequencies
Large market potential for FACTS is within the ac system on a value-added basis, where:
The existing steady-state phase angle between bus nodes is reasonable
The cost of a FACTS device solution is lower than HVDC or other alternatives
The required FACTS controller capacity is less than 100% of the transmission throughput rating

26. FACTS Attributes for Different Controllers

27. FACTS Implementation - STATCOM E2 / 2 E1 / 1 P&Q IX
Regulating Bus Voltage
Can Affect Power Flow Indirectly / Dynamically
P1 = E1 (E2 . sin ())/X

28. FACTS Implementation - TCSC
P&Q X
Line Impedance Compensation
Can Control Power Flow Continuously
P1 = E1 (E2 . sin ()) / Xeff
Xeff = X- Xc
The alternative solutions need to be distributed; often series compensation has to be installed in several places along a line but many of the other alternatives would put both voltage support and power flow control in the same location. This may not be useful. For instance, if voltage support were needed at the midpoint of a line, an IPFC would not be very useful at that spot. TCSC for damping oscillations ...

29. FACTS Implementation - SSSC
P&Q I X
P1 = E1 (E2 . sin ()) / Xeff
Xeff = X - Vinj/I

30. FACTS Implementation - UPFC
P&Q I X
Regulating Bus Voltage and Injecting Voltage In Series With the Line
Can Control Power Flow
P1 = E1 (E2 . sin ()) / Xeff
Xeff = X - Vinj / I
Q1 = E1(E2 - E2 . cos ()) / X

31. FACTS Implementation - UPFC
Shunt Inverter
Series Inverter
Unified Power Flow Controller
Series Transformer
Shunt
Transformer

32. FACTS Implementation - STATCOM + Energy Storage
P&Q I X
Regulating Bus Voltage Plus Energy Storage
Can Affect Power Flow Directly / Dynamically
Plus Energy Storage

33. FACTS Implementation - SSSC + Energy Storage
P&Q I X
Voltage Injection in Series Plus Energy Storage
Can Affect Power Flow Directly / Dynamically
and sustain operation under fault conditions
Plus Energy Storage

34. FACTS Implementation - UPFC + Energy Storage E2 / 2 E1 / 1 P&Q IX
Regulating Bus Voltage + Injected Voltage + Energy Storage
Can Control Power Flow Continuously, and Support Operation Under Severe Fault Conditions (enhanced performance)
Plus Energy Storage

35. FACTS Implementation - UPFC + Energy Storage
Shunt Inverter
Series Inverter
Unified Power Flow Controller - SMES Interface
SMES Chopper and Coil
1000μF

36. FACTS Implementation - UPFC + Energy Storage
SMES Chopper and Coil - Overvoltage Protection
UPFC Grounding
MOV

37. FACTS Implementation - TCSC + STACOM + Energy Storage$
Regulating Bus Voltage + Energy Storage + Line Impedance Compensation
Can Control Power Flow Continuously, and Support Operation Under Severe Fault Conditions (enhanced performance)

38. FACTS Implementation - IPFC
P12 = E1 (E2 . sin (1- 2)) / X
P13 = E1 (E2 . sin (1- 3)) / X

39. FACTS Implementation - IPFC
Series Inverter #1
Series Inverter #2
Interline Power Flow Controller
Series Transformer, Line 2
Series Transformer, Line 1

40. Enhanced Power Transfer and Stability: Technologies’ Perspective
Fast
Real Power Injection
and Absorption
Reactive Power Injection
Reactive Power Injection and
Absorption
Compensation
Devices
FACTS Devices
Energy Storage
Electric Grid P Q
Additional
Stability Margin
TSSC
SSSC
UPFC
SMES
Acceleration
Area
Deceleration
Stability
Margin
STATCOM
Increased Power
Transfer

41. Q FACTS + Energy Storage P
The Role of Energy Storage: real power compensation can increase operating control and reduce capital costs
STATCOM
Reactive Power Only
Operates in the vertical axis only P
MVA Reduction
P - Active Power
Q - Reactive Power
The Combination or Real and Reactive Power will typically reduce the Rating of the Power Electronics front end interface.
Real Power takes care of power oscillation, whereas reactive power controls voltage.
STATCOM + SMES
Real and Reactive Power
Operates anywhere within the
PQ Plane / Circle (4-Quadrant)

42. FACTS + Energy Storage - Location Sensitivity
SMES Power (MW)
Additional Power Transfer(MW)
Closer to generation
Closer to load centers

43. Enhanced Voltage and Stability Control
Enhanced Power Transfer and Stability:
Location and Configuration Type Sensitivity
2 STATCOMs
1 STATCOM + SMES
Voltage and Stability Control
Enhanced Voltage and Stability Control
System Frequency
(Hz)
60.8
59.2
time (sec)
(2 x 80 MVA Inverters)
( 80 MVA Inverter + 100Mjs SMES)
No Compensation

44. FACTS For Optimizing Grid Investments
FACTS Devices Can Delay Transmission Lines Construction
By considering series compensation from the very beginning, power transmission between regions can be planned with a minimum of transmission circuits, thus minimizing costs as well as environmental impact from the start.
The Way to Proceed
· Planners, investors and financiers should issue functional specifications for the transmission system to qualified contractors, as opposed to the practice of issuing technical specifications, which are often inflexible, and many times include older technologies and techniques) while inviting bids for a transmission system.
· Functional specifications could lay down the power capacity, distance, availability and reliability
requirements; and last but not least, the environmental conditions.
· Manufacturers should be allowed to bid either a FACTS solution or a solution involving the building of (a) new line(s) and/or generation; and the best option chosen.

45. Specifications Converter (Functional rather than Technical )
Transformer Connections
Higher-Pulse Operation
Higher-Level Operation
PWM Converter
Pay Attention to Interface Issues and Controls
Converter
Increase Pulse Number
Higher Level
Double the Number of Phase-Legs and Connect them in Parallel
Connect Converter Groups in Parallel
Use A Combination of several options listed to achieve required rating and performance

46. Cost Considerations

47. Cost Considerations Cost structure
The cost of a FACTS installation depends on many factors, such as power rating, type of device, system voltage,
system requirements, environmental conditions, regulatory requirements etc. On top of this, the variety of options available for optimum design renders it impossible to give a cost figure for a FACTS installation.
It is strongly recommended that contact is taken with a manufacturer in order to get a first idea of costs and
alternatives. The manufacturers should be able to give a budgetary price based on a brief description of the
transmission system along with the problem(s) needing to be solved and the improvement(s) needing to be
attained.
(*) Joint World Bank / ABB Power Systems Paper
Improving the efficiency and quality of AC transmission systems

48. Technology & Cost TrendsI
$$$ $
additional cost savings possible

49. Concerns About FACTS
Cost
Losses
Reliability

50. Economics of Power Electronics Sometimes a mix of conventional and FACTS systems has the lowest cost Losses will increase with higher loading and FACTS equipment more lossy than conventional ones Reliability and security issues - when system loaded beyond the limits of experience Demonstration projects required
Cost of System
100% Power Electronics
100% Conventional
Delta-P1
Delta-P2
Delta-P3
Delta-P4
Stig Nilson’s paper

51. Operation and Maintenance
Operation of FACTS in power systems is coordinated with operation of other items in the same system, for smooth and optimum function of the system. This is achieved in a natural way through the Central Power System Control, with which the FACTS device(s) is (are) communicating via system SCADA. This means that each FACTS device in the system can be operated from a central control point in the grid, where the operator will have skilled human resources available for the task. The FACTS device itself is normally unmanned, and there is normally no need for local presence in conjunction with FACTS operation, although the device itself may be located far out in the grid.
Maintenance is usually done in conjunction with regular system maintenance, i.e. normally once a year. It will require a planned standstill of typically a couple of days. Tasks normally to be done are cleaning of structures and porcelains, exchanging of mechanical seals in pump motors, checking through of capacitors, checking of control and protective settings, and similar. It can normally be done by a crew of 2-3 people with engineer´s skill.
Joint World Bank / ABB Power Systems Paper
Improving the efficiency and quality of AC transmission systems

52. Impact of FACTS in interconnected networks
The benefits of power system interconnection are well established. It enables the participating parties to share the benefits of large power systems, such as optimization of power generation, utilization of differences in load profiles and pooling of reserve capacity. From this follows not only technical and economical benefits, but also environmental, when for example surplus of clean hydro resources from one region can help to replace polluting fossil-fuelled generation in another.
For interconnections to serve their purpose, however, available transmission links must be powerful enough to safely transmit the amounts of power intended. If this is not the case, from a purely technical point of view it can always be remedied by building additional lines in parallel with the existing, or by uprating the existing system(s) to a higher voltage. This, however, is expensive, time-consuming, and calls for elaborate procedures for gaining the necessary permits. Also, in many cases, environmental considerations, popular opinion or other impediments will render the building of new lines as well as uprating to ultrahigh system voltages impossible in
practice. This is where FACTS comes in.
Examples of successful implementation of FACTS for power system interconnection can be found among others between the Nordic Countries, and between Canada and the United States. In such cases, FACTS helps to enable mutually beneficial trade of electric energy between the countries.
Other regions in the world where FACTS is emerging as a means for AC bulk power interchange between regions can be found in South Asia as well as in Africa and Latin America. In fact, AC power corridors equipped with SVC and/or SC transmitting bulk power over distances of more than km are a reality today.
Joint World Bank / ABB Power Systems Paper
Improving the efficiency and quality of AC transmission systems

53. Power Quality Issues 1 – Background
2 – The Need For An Integrated Perspective of PQ
3 – Harmonics
4 – Imbalance
5 – Voltage Fluctuations
6 – Voltage Sags
7 – Standards, Limits, Diagnostics, and Recommendations
Flexibility, Compatibility, Probabilistic Nature, Alternative Indices
8 – Combined effects
9 – Power Quality Economics
10 – Measurement Protocols
11 – Probabilistic Approach
12 – Modeling & Simulation
13 – Advanced Techniques
(Wavelet, Fuzzy Logic, Neural Net, Genetic Algorithms)
14 – Power Quality Programs

54. Compatibility: The Key Approach

55. Relative Trespass Level (RTL)
Uk - measured or calculated harmonic voltage
Uref - harmonic voltage limit (standard or particular equipment)
k - harmonic order

56. Harmonic Distortion Diagnostic Index Applying Fuzzy Logic Comparisons Alternative Approach
Possible
Problems
Caution
Severe
Distortions
Dangerous
Levels
Normal A B C D E F G
RTL 1
Below
Heating
Over
Hot
Very a b c d e
Magnitude $ Phase Angle
Equipment Malfunction
Individual Harmonics (Vh)
Fuzzy - Color Code Criteria
No Problem
Possible Problems
Imminent Problems

57. How To Interpret This?

58. How To Interpret This?

59. The Total Quality Environment
Generation
Delivery
Conversion
Processing
Central
Station
T&D
AC-AC
Supplies
Motion
Environmental
Maintainability
Availability
Safety
Efficiency
Reliability
Performance
Price
Power Quality
Power System Value Chain
Power Electronics Systems and Components
SMES
Batteries
FACTS
PQ Parks
UPS
Appliances
INPUTS
OUTPUTS
Value Dimensions
Energy
Power
Communication
Light / Motion
Utility
User
The Total Quality Environment

60. Conclusions
Future systems can be expected to operate at higher stress levels
FACTS could provide means to control and alleviate stress
Reliability of the existing systems minimize risks (but not risk-free)
Interaction between FACTS devices needs to be studied
Existing Projects - Met Expectations
More Demonstrations Needed
R&D needed on avoiding security problems (with and w/o FACTS)
Energy storage can significantly enhance FACTS controllers performance

61. Conclusions A Balanced and Cautious Application
The acceptance of the new tools and technologies will take time, due to the computational requirements and educational barriers.
The flexibility and adaptability of these new techniques indicate that they will become part of the tools for solving power quality problems in this increasingly complex electrical environment.
The implementation and use of these advanced techniques needs to be done with much care and sensitivity. They should not replace the engineering understanding of the electromagnetic nature of the problems that need to be solved.

62. Questions and Open Discussions