Wind Power Application State of the Art Hugh Nguyen Supervisor - - PowerPoint PPT Presentation

Wind Power Application – State of the Art

Hugh Nguyen Supervisor Engineering – Resource Integration

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Outline

• 1. About PSE
• 2. PSE Wind Assets
• 3. Wind Integration and Benefits
• 4. Pacific Northwest Transmission Requirements

Transmission and wind characteristics

• 5. Wind Power Application -- State of the Art:

Turbine Forecasting Technical challenges (i.e., modeling, VAR support, stability, etc.)

• 6. Wind Bright Future

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PSE - a Washington Company

• State’s oldest and largest utility
• 6,000 sq. miles
• 11 counties
• 1 million+ electric customers
• 735,000 natural gas customers
• Public Service Company with

an obligation to serve

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PSE Wind Assets

• 429 MW of capacity and counting
• Makes up 5% of PSE’s annual average load

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Relative Size of Wind Turbines

Vestas V80-1.8MW Statue of Liberty 2-Story House 2-Story House

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Wind Turbine Facts

• Rotor Dia = 80 meters
• Swept Area = 5,026 m2
• Rotation = 15.5 RPM
• Gen Voltage = 690 Volts
• Capacity = 1,800 kW
• Nacelle Weight = 77 tons
• Rotor Weight = 41 tons
• Tower Weight = 105 tons
• Total Weight = 223 tons

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Inside a Wind Turbine

• 1. Hub controller 2. Pitch cylinder 3. Main shaft 4. Oil

cooler 5. Gearbox 6. VMP-Top controller with converter 7. Mechanical disc brake 8. Service crane 9. Transformer 10. Blade hub 11. Blade bearing 12. Blade 13. Rotor lock system 14. Hydraulic system 15. Hydraulic clamp ring 16. Turntable 17. Machine foundation 18. Yaw gears 19. OptiSpeed™ generator

• 20. Air cooler for generator

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PSE Wind Integration

• Wild Horse
• Integrated in PSE’s balancing authority
• Hopkins Ridge
• Integrated in BPA’s balancing authority
• Klondike III
• Integrated in BPA’s balancing authority

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Managing Wind Variability

Utilize Mid-Columbia hydro generation

Rely on wind forecast for flexibility Use load following flexibility at PSE hydro

Purchase needed reserves from other BA’s Call on combustion turbines to meet unexpected wind generation gaps Ramp internal resources Curtail wind if truly necessary, as a last resource

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Wind Benefits

• Clean emission-free wind energy that reduces

the impact on climate change

• A federal wind power credit could be passed

through to Puget Sound Energy customers.

• The credit is a federal income tax benefit from PSE's ownership
• f wind power generating plants. If approved by the Washington

Utilities and Transportation Commission, the wind credit will rise 28¢ and bring the total monthly credit to $1.68 for homes using 1,000 kwh/month.

• Renewable Energy Credit (REC). PSE is

monetizing these until 2011, and seeing market rates ~ $5/Mwh

• Jobs created and local economies benefit

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Power Type Legend Hydro Thermal Gas Storage Wind

PSE Existing Resources

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Hopkins Ridge Wind Project

• Developed by Renewable Energy

Systems

• All-in cost of $200 million in 2005
• 150 MW
• 38% capacity factor – YTD 2008
• Vestas Turbines
• 1.8 MW Capacity
• 220 feet tall at hub
• 320 feet to tip of blade

Project Site

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Wild Horse Wind Project

• Developed by Horizon Wind
• ≈11 miles east of Ellensburg in

Kittitas County, Washington

• Shrub steppe habitat - primarily grazing

land

• ≈8-mile 230kV transmission line to PSE IP

Line at new Wind Ridge Substation

• 230 MW
• Capacity factor 37% - YTD 2008
• Private land owned by PSE
• ≈5,400 acres (≈87 WTGs)
• ≈1,280 acres (site access)
• State land leased by PSE
• DNR ≈2,560 acres (≈31 WTGs)
• WDFW ≈640 acres (≈9 WTGs)
• Five (5) transmission leases
• All-in cost of $380 million in 2006
• Commercial Operation Dec 22, 2006

Project Area

Kittitas County

Project Site

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Wind Characteristics

• Regulation and Load Following
• Variation will dictate the use of system reserves
• Relying on wind during peak conditions is

less than ideal

• Accurate forecast into the hour is premium
• Usually rich in remote locations therefore

requiring more transmission to transfer to load center

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Wind Variability

• Wind speed varies

every hour

• Forecast uncertainty
• System level plan for

daily or weekly forecast

• Schedule for

upcoming O&M activities

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Wind Variability

One Hour Period

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Voltage Control

• Hopkins Ridge
• 6 Hour Trace
• August 10, 2006
• Varying Output
• 5 to 65 MW
• Collection Voltage
• 34.9 to 35.3 kV
• Stable VARs
• System Voltage
• 123.9 to 126.3 kV

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Renewable Resource Strategy

• Identify links between needs and available

resources

• Washington Renewable Portfolio Standard

requirements influence renewable acquisition

• Optimize development and deployment of

resources based on their benefits to:

• Electricity system
• Environment
• Local economies
• Develop/ Acquire smart planning tools that help

integrate resource characteristics effectively

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Objectives

• Determine performance characteristics for

renewable technology

• Investigate how renewable distributed electricity

generation can help address transmission constraints and serve loads

• Identify locations where renewable generation

can effectively be integrated:

• First, Look for weak elements in the system by

simulating impacts from lost transmission or capacity

• Then, identify locations in system where new

generation can provide grid reliability benefits

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Normal System Operation

100 MW 50 MW 280 MW 187 MW 110 MW 40 Mvar 80 MW 30 Mvar 130 MW 40 Mvar 40 MW 20 Mvar 1.0 1.01 pu 1.04 pu 1.04 pu 1.04 pu 0.9930 pu 1.05 pu

67 MW 67 MW 33 MW 32 MW 57 MW 58 MW 21 MW 21 MW 66 MW 65 MW 11 MW 11 MW 23 MW 42 MW 43 MW 28 MW 29 MW 23 MW 23 MW 1 200 MW 0 Mvar 200 MW 0 Mvar

29 MW 28 MW One Three Fo Two Five Six Seven 23 MW

87%

A MVA

82%

A MVA

System does not have operation violations

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Abnormal Condition – A line is out

100 MW 50 MW 280 MW 188 MW 110 MW 40 Mvar 80 MW 30 Mvar 130 MW 40 Mvar 40 MW 20 Mvar 1.00 pu 1.01 pu 1.04 pu 1.04 pu 1.04 pu 0.9675 pu 1.05 pu

45 MW 45 MW 55 MW 53 MW 0 MW 0 MW 58 MW 56 MW 52 MW 51 MW 26 MW 25 MW 43 MW 36 MW 37 MW 24 MW 25 MW 30 MW 30 MW 150 MW 200 MW 0 Mvar 200 MW 0 Mvar

25 MW 24 MW One Three Four Two Five Six Seven 44 MW

83%

A MV A

83%

A MV A

95%

A MV A

156%

A MVA

Then this line gets

• verloaded

(is a weak element) This is a serious problem for the system Planning Solutions: New line to bus 3 OR New generation at bus 3

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Wind Resource Locations

• Generally not heavily populated and far

away from load centers

• Original plan for the area probably not

intended for generation integration

• And “transmission” in the area is usually

weak

i.e., small conductors, limited capacity, and

the system was designed to serve small native loads

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Getting Wind Resources Home

• May require costly transmission upgrades
• Complex and usually involve lengthy

negotiations with neighbor utilities

• Pacific Northwest grid:
• Congested
• BPA manages for most part

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Transmission Constraints

• Wind desperately needs transmission in the PNW

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Goldendale Goldendale

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NW Paths & Seasonal Power Flow Directions

Summer Transfers Winter Transfers Constrained Transmission Path

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OLI ND A OLYMPI A FAI RMONT RAVER MONROE I NGLEDOW PAUL OSTRANDER MARI ON MALI N GRI ZZLY JOHN DAY H ANFORD BELL COULEE NI COLA LANGDON GARRI SON MI DPOI NT MI CA REVELSTOKE SELKI RK ASHE TAFT BI G ED DY MCNARY MERI DI AN

KELLY LAKE

D UNSMUI R BORAH CH EEKYE CRANBROOK SUMMER LAKE ROUND BU TTE EDMONTON ALLSTON DWORSHAK ROU ND MOUNTAI N SCHULTZ ALVEY WI LLI STON VASEU X LK TOWNSEND

P-1 P-2 P-8 P-11 P-9 P-7 P-6 P-4 P-3 P-5 P-10 Path Name & Rating: P-1 -- Northwest-Canada: 3150 MW N-S; 2000 MW S-N P-2 -- West Cascades North: 10200 MW E-W P-3 -- Monroe-Echo Lake: 1200 MW N-S P-4 -- Raver-Paul: 2010 MW N-S P-5 -- North of Hanford: 3700 MW N-S P-6 -- Paul-Allston: 2500 MW N-S P-7 -- North of John Day: 8400 MW P-8 -- West Cascades South: 7000 MW E-W P-9 -- South of Allston: 2640 MW N-S P-10 -- West of McNary: 2980 MW E-W P-11 – West of Hatwai: 4300 MW E-W

Major Transmission Paths around Washington

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Proposed NW Transmission Projects

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Power System Basics

• Three major power system components

Generation creates electric power Load consumes electric power Transmission transmits electric power

from generation to load center

Distribution distributes power to load

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Transmission and Distribution

• Typical high voltage transmission voltages
• 500, 345, 230, 161, 138 and 69 kV
• Transmission tends to be a grid system
• Each bus is typically supplied from two or more

directions

• Lower voltage lines are used for distribution
• Typical voltage of 12 kV
• tend to be radial
• Transformers are used to change the voltage

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Ideal Vs. Real Power System Operation

• Ideal
• Generators supply energy and loads remove energy
• Has no transmission constraints
• Real
• Different operating control centers impose different

supply and demand constraints

• Transmission system imposes constraints.
• Line outage dictates the flowability of power

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Power System Analysis

• Major Challenges
• Turbine design
• Plant design
• Short project lead times
• Modeling complexity
• Harmonics
• Capacitor Switching Transients
• Frequency response
• Phenomena dealing with machine interactions and stability
• Others not yet known

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Turbine Design

• Fixed Speed Design
• Early adoption by industry
• Induction generator
• Simple, Robust, Proven
• Max efficiency at one wind

speed

• Fluctuating voltage and

power to the grid

• Uncontrollable reactive

power

• High structural stresses in

turbine and tower

• Variable Speed Design
• Dominant design today
• Induction generator
• High efficiency over broad

range of wind speed

• Generator torque fairly

constant

• Improved power quality
• Reduced mechanical

stress

• Complex power

electronics

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Induction Generator

• Asynchronous generator allows slip to keep

rotor speed close to synchronous speed

• Pitch system used to control or limit speed
• Minimizes gust loads on turbine structure
• Requires variable rotor current, or double-feed,

to capture power from speed variation

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Standard Generator Control

• Type A: Simple Induction Generator
• Type B: Induction Generator with Variable Rotor

Resistance

• Type C: Doubly Fed Rotor
• Type D: Full Converter

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Grid Interconnection Issues

• Wind Variability
• Daily or Weekly
• Hourly
• Voltage Control
• Low Voltage Ride-Through
• Reactive Power
• Power quality
• System Harmonics
• Transients

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Power Quality Distortion Frequencies

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Harmonics

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Switching Transients

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Low Voltage Ride Through

• Older wind turbines without external devices

would disconnect from grid on low-voltage event

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Low Voltage Ride Through

• Contemporary units can tolerate low-voltage, or

even zero voltage with external devices (D-VAR), and stay online through event

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Simplified 1-Line Diagram*

• 230 kV stepped

down to 34.5 kV

• And further

stepped down to 690 V at the turbines

* Taken from RAI’s Harmonics

Measurements Reports

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Example of Harmonic Analysis

• Harmonic resonances due to combination of
• Substation capacitor banks
• Reactance from system equivalent impedance
• Transmission line and transformers
• System collector cables.
• Measurements revealed
• Some issues were found upon reviewing a broad

spectrum of harmonic currents

• Harmonic currents existed and confirmed based on

data recorded at turbines terminals.

• Effective filtering suppressed harmonic currents

well below limits

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Simulations – Existing System

230 kV system

normally open 34.5 k Tie line HV Reactor HV OH Line CAP21 CAP23 CAP22 CAP13

CAP12 CAP11

Sub Trans 1 Substation HV cap bank Sub Trans 2

Bar 2

Wild Horse

Wind Ridge

Bar 1

Trans Delta 1 Trans Delta 2

DIgSILENT

• Harmonic

currents out of bandwidth

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230 kV system

normally open 34.5 k Tie line HV Reactor HV OH Line CAP21 CAP23 CAP22 CAP13

CAP12 CAP11

Sub Trans 1 Substation HV cap bank Sub Trans 2

Bar 2

Wild Horse

Wind Ridge

Bar 1

Trans Delta 1 Trans Delta 2

DIgSILENT

Simulations – Effective Filtering

• 34.5 kV Cap Banks used as Filters
• Harmonic

currents within bandwidth

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Wind Bright Future

• Market Share
• Wind is a mature reliable technology
• PTCs and RPS standards will drive additional wind

development throughout the U.S.

• Units are getting bigger and more complex
• Grid Interconnection
• Increased use of wind turbines and external devices

for voltage stability and VAR compensation

• Improved LVRT capability with D-VAR
• Can operate with leading and lagging power factors
• Hurdles need to go over
• Transmission limitations
• Additional dispatchable generation
• System reliability