62
Brief Overview of CURENT Control Architecture for the Future Power Grid Kevin Tomsovic University of Tennessee CURENT Center Director [email protected]
Brief Overview of CURENT
Control Architecture for the Future Power Grid
Kevin Tomsovic
University of Tennessee
CURENT Center Director
NSF Engineering Research Centers
• NSF program of focused research on an engineering problem. Among the most
significant investments NSF will make in an area with support for up to 10 years.
• Program elements include:
• Outreach (K-12 education)
• Research experience for undergraduates
• Entrepreneurship training
• Industry program
• Systems engineering approach
• International collaboration
CURENT – NSF/DOE ERC
• One of only two ERCs funded jointly by NSF and DOE. Core budget: ~$4M/year
for 5-10 years but highly leveraged to be able to fully support programs.
• CURENT only ERC devoted to wide area controls and one of only two in power
systems.
• Partnership across four universities in the US and three international partner
schools. Many opportunities for collaboration.
• Expect 50+ industry members to eventually join. Presently have 27 members.
• Center began Aug. 15th 2011
US Wind and Solar Resources
Best wind and solar sources are
far from load centers.
Transmission networks
must play a central role in
integration.
http://www.eia.doe.gov/cneaf/solar.renewables/ilands/fig12.html
Wind
Solar
Population
4
Rapid Retirement of Coal Plants in North America
Change in generation mix challenge
long term planning
https://www.eia.gov/todayinenergy/detail.cfm?id=7290
Brattle Group http://grist.org/article/2010-12-13-new-reports-show-huge-wave-of-coal-plant-closures-coming/
http://www.ucsusa.org/clean-energy/coal-and-other-fossil-fuels/natural-gas-gamble-risky-
bet-on-clean-energy-future#.VmOc48pgvAo5
Growth in electricity consumption
• Transmission investment has lagged generation investment and led to
several bottlenecks in the Eastern interconnect and Western interconnect.
• Limited transmission impacting reliability and cost, preventing full use of
renewables
• Inflexible capabilities leads to inefficient investment in grid infrastructure
Transmission constraint events
US Grid Infrastructure – Aging and Inflexible
6
CURENT Vision
• A nation-wide transmission grid that is fully monitored and dynamically controlled for high efficiency, high
reliability, low cost, better accommodation of renewable sources, full utilization of storage, and
responsive load.
• A new generation of electric power and energy systems engineering leaders with a global perspective
coming from diverse backgrounds.
Multi-terminal HVDC
Monitoring and sensing Communication
Control and Actuation
Computation
7
Electromechanical Wave Phenomena
Wide Area Measurement
FNET Monitors
in the Field
FDR Sensor
Unique Capabilities: UWA real-time grid monitoring system at UTK – Yilu Liu
8
Power Grid
Measurement
&Monitoring
Communication
Actuation
PMU0PMU
PMUPMU0
PMUFDR
WAMS
Communication
PSS
Generator
Storage
HVDC
Wind Farm
FACTS
Solar Farm
Responsive Load
Wide Area Control of
Power Grid
What is CURENT?
9
Three-plane DiagramEn
ablin
g T
echn
olog
ies
Engi
neer
ed S
yste
ms
Fund
amen
tal
Know
ledg
e
ControlControl Actuation Actuation
Control Architecture
Actuator & Transmission Architecture
System-level Actuation FunctionsCommunication
& Cyber-security
Estimation
Economics & Social Impact
Barriers· System complexity· Model validity· Multi-scale· Inter-operability
Barriers· Poor measurement design· Cyber security· Actuation & control
limitation
· Barriers· Lack of wide-area control
schemes· Measurement latency· Inflexible transmission
systems
MonitoringMonitoring ModelingModeling
Situational Awareness & Visualization
Wide-area Measurements
Modeling Methodology
Hardware Testbed
Large Scale Testbed
Testbeds
Control Design &
Implementation
Day Hour Minute Second Cycle
Device
Substation
Region
Balancing
Authority
Wide Area
Ultra-wide Area
AGC
LTC
AVR
UFLS
SVC
Fixed Comp.
RAS
Schemes
Unit
CommitmentEconomic
Dispatch
PSS
HVDC
Device
Protection
Today’s Operations
Some Wide Area and Some Fast but not Both
Limited communication
Minimal sensing
Traditional uncoordinated controlsDistributed coordinated actuation with
extensive measurements
11
Economic
Dispatch
Day Hour Minute Second Cycle
Device
Substation
Region
Balancing
Authority
Wide Area
Ultra-wide
AreaIntegrated Secure
Dispatch and
Frequency Control
Demand
Response
Distributed
Frequency Control
Frequency Control Wide area with distributed actuation
Wide area communication Distributed coordinated actuation
Renewables
Support
UFLS
AGC
Extensive Sensing
HVDC
FACTS
12
CURENT Control and Coordination Architecture
Resilience and scalability by
o Distributed – renewables,
grid, storage, and demand
as active control participants
o Measurements (learning
and adaptive, data-driven)
o Modularized, hierarchical,
global signals so distributed
with context
o Sharing resources (reduced
impact of uncertainty)Contextual
Level k-1
Contextual
Level k
Global /Local
Control
Global signals
Frequency and time
Wide area measurements
C1 tier
C2-C3 layers
Local measurements
13
Large Scale Testbed
Objectives
• Develop a large scale simulation platform
to demonstrate CURENT technology
• Establish regional system models for wide area
system studies
• Demonstrate how CURENT technology can
improve the existing systems
NPCC system with PMU placement for observability
14
• Regional – NPCC and WECC: Maintain unique
characteristics with manageable data issues
• Show how wide-area monitoring and control can
improve voltage security and oscillations in NPCC
• Dynamic modeling for 179+ bus system in WECC
System Models
• Highly aggregated systems. Integration with
Hardware testbed and RTDS
• Large system: EI 70,000 bus & WECC 15,000 bus
• Detailed positive sequence models
• Future scenario studies
Hardware System Testbed
Objectives
• Emulate grid with interconnected clusters of
scaled-down generators and loads.
• Use modular, reconfigurable converters for
generators, loads, flexible network, and scenario
emulation.System Models
• Developed several emulators: synchronous generator,
wind generator (2 types), solar, flywheel, transmission
line, ZIP load, and induction motor.
• Four clusters constructed. Use of real measurement
(PMU and FNET) data as well as communication.
• Two area system demonstrated with voltage collapse
scenario. PMU based.
• Remote control-room type environment using large
display wall and Labview environment has been setup to
allow a more coordinated operation.
15
Research Roadmap
16
Example Wide Area Controls
• Sharing resources among different devices• Flat systems - distributed frequency control
• Communications• Distributed damping control
• Robustness• Sensor/communication failures
• Actuator availability
17
Distributed Contextual Control: Frequency
Regulation for High Penetration of Wind
Generation
Maryam H. Variani, Kevin Tomsovic
Motivation
• Decline of the Eastern Interconnection frequency response of about 60-70 MW/0.1HZ/year.
• NERC new reliability standard: BAL003- balancing area frequency response obligation.
Today:
Each BA must balance loads and
resources within its borders
Source : Briefing on Energy Imbalance Market, Mark Rothleder, Califorinia ISO
In an EIM:
The market dispatches resources
across BAs to balance energy
More
Primary Frequency Response
• Energy Imbalance Market (EIM):
19
Introduction
• Frequency regulation at conventional units needs to be modified to cope with high penetration of wind and PV.
• Studies show that it may be both technically and economicallyfeasible for wind plants to supply regulation under somecircumstances.
• Two-Level Control Structure
o To allow high penetration (e.g., 50%) of renewable resources,conventional controls need to be replaced by a simpler structure.
o The proposed structure consists of local control operating within aglobal context of situational awareness at different levels.
Contextual Control
Selects one of a finite number of system-level
control goals that best reflect needs based on
overall system status at a given moment.
Local Control
Individual components andloads operate in a manner to follow somedesired trajectory based on local observationsto manage deviations.
Flatness-based approach is well adopted to control systems
in two levels of planning, trajectory generation, and
tracking the desired trajectories.
20
Definition
o 𝒚 = 𝒉(𝒙, 𝒖, 𝒖ሶ , … , 𝒖(𝜸))o 𝒙 and 𝒖 are computable without integration:
𝒙 = 𝝋 𝒚, 𝒚ሶ , … , 𝒚 𝜶−𝟏
𝒖 = 𝝍(𝒚, 𝒚ሶ , … , 𝒚(𝜶))
F l a t S y s t e m s
The nonlinear system
𝒙ሶ = 𝒇 𝒙, 𝒖 𝒙 ∈ 𝑹𝒎, 𝒖 ∈ 𝑹𝒏
is said (differentially) flat if and only if there exists n independent scalarfunctions 𝒉 = (𝒉𝟏, … , 𝒉𝒏) such that:
The vector 𝐲 is called the flat output.
21
𝒚(𝜶)
= 𝒗
𝒙 𝒕 , 𝒖(𝒕)
𝒙ሶ = 𝒇 𝒙, 𝒖
(𝒚 𝒕 , 𝒚ሶ𝒕 , … , 𝒚(𝜶)
(𝒕))
Trajectory Generation
To every curve 𝒕 ↦ 𝒚(𝒕) enough differentiable,
there corresponds a trajectory
𝒕 ↦𝒙 𝒕𝒖 𝒕
that identically satisfies the system
equations.
F l a t S y s t e m s
22
Trajectory Tracking
Stabilization of the tracking error:
Given the reference with ,
assuming that 𝑦, … , 𝑦(𝛼−1) are measured or are suitably estimated.
By setting:
The gains 𝒌𝒊, 𝒊 = 𝟎, … , 𝜶 − 𝟏, being chosen such that all the roots of thepolynomial 𝒑𝜶 + 𝒌𝜶−𝟏𝒑𝜶−𝟏 + ⋯ + 𝒌𝟏𝒑 + 𝒌𝟎 have negative real part.
𝒆 = 𝒚 − 𝒚𝒓𝒆𝒇
F l a t S y s t e m s
23
Control Structure
• Flatness-based control diagram
Trajectory
Generation𝒗 = −𝑲𝒆 𝒚(𝜶)
u
x
u x
z x
+-
𝑢 = 𝑎(𝑦, 𝑦ሶ , … , 𝑦(𝛼))𝑥ሶ = 𝑓(𝑥, 𝑢)
F l a t S y s t e m s
24
Background: ACE-Based AGC
10
89
4
1
6
7
5
32Area 2
Area 1
Area 3
C o m p r e h e n s i v e F l a t n e s s - B a s e d A G C
Economic
Dispatch
Every 5
minutes
• Conventional AGC is performed based on integration of AreaControl Error(ACE) for each BA.
25
• Conventional AGC is performed based on integration of AreaControl Error(ACE) for each BA.
Background: ACE-Based AGC
10
89
4
1
6
7
5
32Area 2
Area 1
Area 3
න 𝐴𝐶𝐸
Tie line
Frequency
Every 2-4
seconds
𝐴𝐶𝐸 = Δ𝑃𝑡𝑖𝑒 + 𝛽Δ𝑓
C o m p r e h e n s i v e F l a t n e s s - B a s e d A G C
26
Flatness Based AGC
• Flatness-based approach is applied to automatic generation
control(AGC) of multi-area systems with wind generation units.
• In two level control structure, secondary control action represents
local control and the reference trajectory , to be tracked by the local
control, are determined in the contextual control.
C o m p r e h e n s i v e F l a t n e s s - B a s e d A G C
27
Two Level Flatness-based AGC Structure
10
89
4
1
6
7
5
32Area 2
Area 1
Area 3
Economic
Dispatch
Phase
Frequency
Every 5
minutes
As fast as practical
constrains allow
C o m p r e h e n s i v e F l a t n e s s - B a s e d A G C
28
Multi-Machine Model
Synchronous machine classical model including network, prime mover
and governor for generator 𝑖:
𝜹ሶ𝒊 = 𝝎𝒊 − 𝝎𝒔
F l a t n e s s - B a s e d A G C w i t h S y n c h r o n o u s M a c h i n e s
Network
Governor
Prime Mover 29
Flat System Model
Flatness-based formulation with 𝜹𝒊 as flat output for each generator:
𝜹ሶ𝒊 = 𝝎𝒊 − 𝝎𝒔
𝜹𝒊ሸ =
𝟏
𝟐𝑯
𝟏
𝝉𝑻𝑷𝒈𝒗𝒊 −
𝟏
𝝉𝑻𝑷𝒎𝒊 − 𝐃𝜹ሷ
𝒊 −𝑬𝒊𝑽𝒊
𝐱′𝒅𝒊𝜹ሶ
𝒊𝐬𝐢𝐧(𝜹𝒊 − 𝜽𝒊)
F l a t n e s s - B a s e d A G C w i t h S y n c h r o n o u s M a c h i n e s
30
Trajectory Tracking
• Finding appropriate speed changer position, through a feedback law,
to maintain system stability, restore the frequency nominal value and
track the scheduled net interchange.
• System perturbations: load changes, generation loss, wind
generation variations.
• The feedback law:
F l a t n e s s - B a s e d A G C w i t h S y n c h r o n o u s M a c h i n e s
𝒆𝒊 = 𝜹𝒊 − 𝜹𝒊∗
𝒗𝒊=𝒗𝒊∗ − σ 𝒌𝒊𝒋
𝟑𝒋=𝟎 𝒆𝒊
(𝒋)
• The input is updated
every 2 sec as it is
performed in
conventional AGC.
• Generator ramping
rate constraint is
considered.31
Simulation: NPCC System
NPCC 140 Bus, 48 Generators System
Total Capacity ≈ 28 GW
F l a t n e s s - B a s e d A G C w i t h S y n c h r o n o u s M a c h i n e s
User Defined Model
(UDM) in TSAT:
32
Simulation: NPCC System
Scenario 1: Load Shedding 450 MW at t=100 sec in PJM
F l a t n e s s - B a s e d A G C w i t h S y n c h r o n o u s M a c h i n e s
ISO-NE_Flatness-basedIESO_Flatness-based
MISO_Flatness-based
ISO-NE_ACE-basedIESO_ACE-based
MISO_ACE-based
ISO-NE_Flatness-basedIESO_Flatness-based
MISO_Flatness-based
ISO-NE_ACE-basedIESO_ACE-based
MISO_ACE-based
PJM_Flatness-basedNYISO_Flatness-based
PJM_ACE-basedNYISO_ACE-based
PJM_ACE-basedNYISO_ACE-based
PJM_Flatness-basedNYISO_Flatness-based
Active Power Tie Line Flow
33
Simulation: NPCC System
Scenario 2: Wind Variation , total capacity
F l a t n e s s - B a s e d A G C w i t h S y n c h r o n o u s M a c h i n e s
ISO-NE_Flatness-basedIESO_Flatness-based
MISO_Flatness-based
ISO-NE_ACE-basedIESO_ACE-based
MISO_ACE-based
PJM_Flatness-basedNYISO_Flatness-based
PJM_ACE-basedNYISO_ACE-based
Tie Line Flow
ACE-basedFlatness-based
Frequency
Wind Power
34
Comments
• Two level control structure based on flat systems properties is studied for synchronous and
DFIG machines for frequency regulation.o Flatness-based AGC for synchronous machines Two level control consisting of local and contextual controllers substitutes the ACE-based AGC.
Decoupling into n linear controllable sub-systems in canonical form results in decentralized control.
o Flatness-based DFIG
Two level control consisting of trajectory generation and trajectory tracking replaces the field oriented
based method to control active and reactive power.
Trajectories are generated through algebraic equations rather than PI controllers.
Linear control methods such as pole placement and LQR replace the PI controller to track the desired
states.
• The two developed models build a generic AGC with two level controls at each machine
working in coordination with higher level controls for planning.
• The model can easily be adopted to new market structures.
35
Distributed Damping Control:Communication Considerations
May Mahmoudi Kevin Tomsovic
Wide Area Control of Power Grid
• The addition of wide-area feedback control to frequently usedcontrols is an effective additional layer of defense against blackouts.
• Centralized Control : a single controller is able to measure all thesystem outputs, compute the optimal control solution, and applythat action to all actuators in the network, within one samplingperiod.
As power networks are large-scale systems, both computationally and geographically, a Centralized Wide
Area Controller is practically difficult to implement.
37
Non-Centralized Controllers
Non-Centralized Controllers
Decentralized Controllers
Do not allow for communication between
local controllers
Distributed Controllers
Communication between different controllers is
exploited to improve the performance
The Proposed Controller in our research is under
this category
38
Proposed Distributed LQR Controller
G G G⋯ ⋯
Distributed LQR Controller for kth Generator
𝑥𝑘−1 𝑥𝑘 𝑥𝑘+1
𝑢 = 𝐾 𝑥
• Objective: Stabilize the system through supplementary excitation control• Graph of physical layer and communication layer coincide.• Full state information exchange is assumed for neighboring generators
39
Distributed LQR Controller
• Consider a set of identical, decoupled linear time invariant dynamical systems:
• LQR Problem Cost Function:
• The LQR problem is in the form of :
40
Power System Model
Distributed LQR Control
Mechanical Power Control Excitation Control Second-Order Model
( ) ( )sm e D DLQR
fdt P P P P
dt H
( ) ( ) ( )s
dt t t
dt
Fourth-Order Model
( ) ( )sm e D
fdt P P P
dt H
( ) ( ) ( )s
dt t t
dt
0
1( ) [ ( ) ( ) ( ) ( )]q fd q d d d
d
dE t E t E t X X I t
dt T
1( ) [ ( ( ))]fd fd A ref t DLQR
A
dE t E K V E V t
dt T
Designed by Proposed Distributed LQR Controller
41
Angle Response for Uniform Test System
• System : 30x30 Mesh structure(Total of 900 generators)
• Disturbance : 0.5 pu power pulse for 0.5 sec on the generator in the center of the mesh
42
Remarks
• From control point of view distributed LQR control problem forPDEs achieves optimal solution, while for discrete models the solutions are sub-optimal and still is an open problem.
• For the given test system we can do the discretization in a way that matches the generators location which makes the controller application to the discrete system feasible. Application of this controller to an arbitrary system is a challenging problem that will
be part of our future work.
43
Distributed Controls – Scalable
• Objectives
o Scalable controls through distributed actuation, on-line measurements, modeling approximations and adapting to
conditions.
• Innovations
o Jointly design controller, communications and sensor needs by enforcing some regularity on connections.
• Example
Two-area system communication structures and
“sparsified” dynamics matrices
44
Two Area System with Communication Links
• Communication link in examples here assumes full state information but more structure can be imposed.
• Control design uses LQR but other methods possible
45
Centralized vs. Distributed vs. Decentralized
No Control
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-0.02
-0.01
0
0.01
0.02
0.03
0.04
0.05
Time(sec)
Sp
ee
d D
ev
iati
on
(ra
d/s
)
G1
G2
G3
G4
Distributed Control
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-0.01
-0.005
0
0.005
0.01
0.015
0.02
0.025
0.03
Time(sec)S
pe
ed
De
via
tio
n(r
ad
/s)
G1
G2
G3
G4
Centralized Control
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-0.01
-0.005
0
0.005
0.01
0.015
0.02
0.025
0.03
Time(sec)
Sp
ee
d D
ev
iati
on
(ra
d/s
)
G1
G2
G3
G4
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5-0.01
-0.005
0
0.005
0.01
0.015
0.02
0.025
0.03
Time(sec)
Sp
ee
d D
ev
iati
on
(ra
d/s
)
G1
G2
G3
G4
Decentralized Control
46
Comments
• Much of the value of wide area information can be
gleaned from a few measurements.
• Best approach is to co-design communication and control
system.
47
Wide-area Damping Controllers:
Failures in Sensors and Actuators
M. Ehsan Raoufat
Kevin Tomsovic
Robust Controls – Fault Resilience
• Objectiveso Reliable controls considering
communication failures, sensor
limits, and unavailability of actuator,
(e.g., renewable resource
variability).
• Innovationso Reconfiguration without need for
redesign, i.e., fault hiding.
Virtual sensor
Virtual actuator
• Example – Virtual Actuator
Reconfiguration
Controller redesign
Fault hiding
WADC
Virtual Actuator
49
Comments
o With our approach damping of WADC system recovered
without the need to redesign the nominal WADC in case of
faults in actuators.
o We consider the sensor faults as communication failures,
cyber-attacks, significant delay in communication links or
failures in the measurement devises.
o Design of the reconfiguration block is independent of the
nominal controller and there is no need to redesign the
nominal controller.
50
Final Summary Comments
o Wide area control is needed to provide flexibility and integrate
renewables
o Wide area controls should be:
Distributed and modular but operating within a context (e.g., flat controls)
Robust to sensor, communication and actuator loss (e.g., virtual
sensors and actuators).
Make efficient use of communications (e.g., distributed controllers)
51
Acknowledgements
This work was supported primarily by the ERC Program of the National Science Foundation
and DOE under NSF Award Number EEC-1041877 and the CURENT Industry Partnership
Program.
Other US government and industrial sponsors of CURENT research are also gratefully
acknowledged.
52
Discussion
Example Value of Improved Controls
• Two 500kV AC lines and +/- 400kV DC line
Designed for transfer of 2000 MW AC and 1440 MW DC
Actual capacity was 1300 MW AC due to instability caused by AVRs
Power system stabilizers allowed increase to 1800 MW AC
Dynamic brake added at Chief Joe allowed up to 2500 MW AC
• Transmission upgrade – third AC line and DC upgrades
AC capacity today about 4800 MW (primarily voltage)
DC capacity today about 3000 MW
1990s work by DOE and BPA on WAMS and WACS a direct result of
this type of need for improved controls.
Northwest Pacific Intertie
Major Research Questions
• Information flow• What information is needed where?
• How much latency can be tolerated?
• Trade-off – more information leads to better decisions but slower response
• Control architecture Do all devices contribute to control?
For which phenomena do devices contribute (some fast and some slow)?
How much contribution is needed to ensure performance?
Trade-off – more devices contributing properly expands viable operating region but requires greater sophistication and cost
• Economics and optimization What functionality should come from markets and what by regulation?
Contributions from certain devices are more cost effective
Trade-off – greater optimization leads to lower cost but requires more voluntary sharing of information and but some services may not lend themselves to an efficient market structure
Design needs to be a series of trade-offs between communication needs, device sophistication, resiliency, speed of response, economic performance and device reliability vs. system reliability.
Future Control Architecture
Strategic Planning
NREL spring retreat
• Brainstorm research directions based on SVT report, IAB, and self-review
• Continue system level projects
• Clarify control architecture and paradigms
• Continue to emphasize demonstration projectso Wide area oscillation damping control
o Wide area voltage control
o >50% renewable penetration
Project Planning Process
Schedule
March
May
July
August
June
April
Monitoring Modeling Control Actuation
Year 4 System Level Projects by Primary Thrust
Advanced HVDC
and Actuator
Technologies
Dynamic State
Estimator and
Parameter
Estimation
Control Paradigms for
Oscillations and
Prevention of
Cascading Outages
Grid Control
Architectures
Measurement:
Universal Grid
Analyzer
MISO
PJM
ERCOT
• Hardware Testbed: Grid Emulator Development and
Real-time Scenario
Demonstration
• Large Scale Testbed 1: Virtual Grid Simulator with an Energy
Management and Control
System
• Large Scale Testbed 2: A National Power Grid Model
Year 4 Testbed Projects
Associated and Sponsored Projects
• Monitoringo Data Architecture and Analytics
o Achieving High-Resolution Situational Awareness in Ultra-Wide-Area Cyber-Physical Systems
o Oscillation Damping Control Design Using Measurement-Based Transfer Function Model
• Modelingo Design of Boundary Measurements to Isolate Zonal Solutions for Large
Interconnected Systems
o Entergy's Response to Smart Grid Investment Grant (SGIG) Program
o SECO/Phasor Based State Estimation
• Controlo A Cyber Physical Framework for Remedial Action Schemes in Large Power
Networks
o Scalable and Flat Controls for Reliable Power Grid Operation with High Renewable Penetration
• Actuationo Power Flow Control using CVSR
Year 5 Research Plans
• Increased system size – complete interconnected
North American system
• Increased percentage of renewables to > 50% with
higher levels of solar, storage and demand response
• Continue moving to faster system events, including
cascading outages
• Improving resilience of monitoring and estimation
• Further development of LTB simulation environment
• Evaluation approach for HTB and LTB with complex
scenarios 0 1 2 3 4
-0.4
-0.2
0
0.2
0.4
0.6
Time (s)
Fre
qu
en
cy e
rro
r (m
Hz)
UGA
Commercial PMU
0 2 4 6 8 10
0.65
0.7
0.75
0.8
0.85
0.9
0.95
0 2 4 6 8 1059.2
59.4
59.6
59.8
60
60.2
Wind Turbine Active Power (p.u.)
Area Frequency (Hz)
Time (s)
Industry Program
Generation Transmission Distribution End-Use
Utilities
RTOs/ISOs
Vendors
Consultants, Research,
Consortia
