Integration of Renewable Resources - Challenges & Solutions

Transcription

1 Existing, Advanced and Smart Grid Technologies for Renewable Integration Presented to IEEE PES San Francisco Chapter Integration of Renewable Resources - Challenges & Solutions By Merwin Brown, Director Electric Grid Research November 15, 2010 This presentation is based in part on work sponsored by the California Energy Commission, but does not necessarily represent the views of, nor has it been approved or disapproved by, the Energy Commission.

2 For most of the 20 th Century, transmission had a relatively simple role moving electricity from central power plants to the consumers. Transmission system behavior was predictable, and under the close control of an operator - much like conducting an orchestra. 2

3 But conducting the 21 st century electric grid is becoming a more hair raising experience: Being connected to the world s largest machines, i.e., a multi-state, multi-country, brittle power grid Accommodating competitive wholesale power markets Serving growing and changing electric loads that are becoming part of the orchestra Dealing with economic and public policy pressures Being instrumental for meeting aggressive renewable energy goals 3

4 Renewable resources portfolio mix for 33% 2020 might look like this But to grid operators, looks Biomass Wind like this Solar ~20,000 MW of New Generation Geothermal The Saga of Renewable Generation and Grid Integration reveals many challenges. 4

5 But renewable resources portfolio mix for 33% 2020 might look like this to grid operators The Saga of Renewable Generation and Grid Integration reveals many challenges. 5

6 The Saga of Renewable Generation and Grid Integration Most central station generation will be located remote from customers. HIGH WINDS Provide Access Building new transmission lines is becoming increasingly difficult and taking longer. 6

7 Building new transmission lines is becoming increasingly difficult and taking longer. Proving need and value Distributing benefits & allocating costs $X New NIMBY Line Assessing and mitigating environmental, land use & aesthetic impacts Getting approval from multiple agencies and jurisdictions Delay in siting & building new transmission is often cited as major barrier to meeting renewable generation policy goals. 7

8 The Continuing The Saga of Renewable Generation and Grid Integration Some renewable generation is unique, e.g., Intermittent Fast Ramp-Rates Over Supply Low Inertia Renewable Power Plant The power grid system must accommodate generation s unique behaviors. 8

9 Solar generation can vary widely from day to day and hour to hour. PV output on sunny day in NV (10 sec sampling) PV output on partly cloudy day in NV (10 sec sampling) Source: NERC Report - Accommodating High Levels of Variable Generation March

10 Wind generation can vary widely from day to day and hour to hour. Tehachapi-area, April

11 Typical load & wind profiles are almost inverse images CAISO Load -- Summer ,000 38,000 36,000 34,000 Load MW 32,000 30,000 28,000 26,000 24,000 22, Hours Total Wind -- Summer ,200 1,100 1,000 Wind Generation Hours Creates issues with load-following ramping and MW oversupply. Thanks to 11

12 Variable generation can increase the need for system flexibility. Thousands of MW of new rapidly dispatchable generation required for regulation and load-following ramping. Source: NERC Report - Accommodating High Levels of Variable Generation March

13 Projected Profiles of Wind and Solar Combined Thanks to Wind and solar generation combined appear to make ramping worse. 13

14 Typical Oversupply Conditions Usually at night in spring Imbalance between Generation and Load Summary: Transmission must accommodate supply uncertainty, rapid up- and down-ramp rates, and over generation. 14

15 Existing infrastructure is constrained. The Continuing The Saga of Renewable Generation and Grid Integration Increase Capacity Renewable Power Plant Difficulties with siting new or upgrading existing transmission Thermal Limits Stability Constraints (Voltage, Transient, Dynamic) N-1 Contingencies 15

16 There are essentially two options for successful expansion and operations of T&D: The traditional build solutions, i.e., investments in wires, towers, poles and power plants, and Renewable Power Plant Improved or new T&D functionalities to make expansion and operations easier and less costly. 16

17 For now we can build our way out of these problems, but at higher renewable penetrations traditional build solutions, i.e., investments in wires, towers and power plants, can t do it alone. New technologies will be needed to make renewable integration easier and less costly especially technologies that make the grid smarter 17

18 New Technologies to Provide Faster Access for New Renewable Plants by putting new power lines in a better light. Underground Transmission High Voltage Direct Current Engineered Compact Designs Advanced Transmission Line Conductors Distributed Renewables & Demand Response Web-based Interactive Stakeholder Siting Tools Cost Allocation & Strategic Benefit Analysis Tools 18

19 New Technologies to Accommodate Unique Renewable Generator Behaviors through a smarter and more flexible grid. Tehachapi Wind Generation - April 2005 Intermittency Ramp Rate Inertia Over Supply Energy Storage & Intelligent Agent (temporal power flow control) Solar and Wind Forecasting Tools Generator and Load Modeling Demand Response Synchrophasor Monitoring Power Flow Control (spatial) Distributed Generation Advanced Intelligent Protection Systems Statistical and Probabilistic Forecasting Tools 19

20 New Technologies for Increased Grid Power Capacity by optimizing the grid for greater power flow. North-South COI California Desert Southwest Dynamic Thermal Ratings Real-Time System Ops (synchrophasors) Power Flow Control (spatial) Energy Storage (temporal power flow control) High Voltage Direct Current Distributed Generation & Demand Response Advanced Intelligent Protection Systems Statistical & Probabilistic Analysis & Planning Tools Advanced Transmission Line Conductors 20

21 Example: Increase Capacity of Transmission Corridors via New Line Materials. High-Temperature, Low-Sag Conductors: New composite core materials replace steel. > 2X power flow through transmission corridor. Upgrade transmission conductor without rebuilding transmission towers 3M s version being tested at San Diego Gas and Electric. 3M High-Temperature Low-Sag Conductor 21

22 Example: Accommodate Renewable Generation Unique Behaviors Individual wind turbines have specific dynamic model based on technology type. POI Power Grid Invalid models fail to predict potential risk. Updating dynamic wind power plant models reduces chances of grid problems. Station transformer is where the individual wind turbines come together as a power plant Collector system with several overhead and underground feeders 22

23 Four basic topologies based on grid interface: o o o o Type 1 conventional induction generator Type 2 wound-rotor induction generator with variable rotor resistance Type 3 doubly-fed induction generator Type 4 full converter interface Wind Dynamic Model Types of Wind Turbine Generator Taken from, Ed Muljadi, NREL, CEC Wind Turbine Dynamic Modeling Project, October 25, 2010 Type 1 Type 2 Type 3 Type 4 generator Plant Feeders PF control capacitor s gene rator Slip power as heat loss ac to dc Plant Feeders PF control capacitors generator ac to dc dc to ac Plant Feeders generator ac to dc dc to ac full power Plant Feeders partial power

24 Combined Regulation Services between CAISO and BPA Cost of Regulation in CAISO $300M/year Double every 3 years Proposed system configuration 2 resources: (flywheel & hydro) BPA & CAISO conventional regulation signals The hydro unit provides smooth/slow regulation and helps maintain the desired energy level in the flywheel The flywheel provides the fast regulation, helps minimize the stress on the hydro unit and keeps its output within the limits

25 Modeled Benefits of the Wide-Area Energy Management & Storage Concept Reduce regulation reserve by up to 30% Provide fast, cost-effective, and efficient ancillary services o o o Minimize wear-and-tear of conventional regulating units Operate conventional regulating units close to their most efficient operating point. Allow the storage devices to excel in specific applications that fit their characteristics Allow the flywheel to serve biased regulation signals and support the flywheel by maintaining a reasonable state-of-charge (SOC) Easy scalable technology Compatibility: o Fully compatible with the existing BPA and CAISO AGC systems o Fully compatible with the other technologies such as ACE Diversity Interchange (ADI) Can be used with the other Balancing Authorities

26 Two Views: August 10th, 1996, California-Oregon Intertie Power Flow During Generator Trip Observed COI Power (Dittmer Control Center) What synchrophasors showed Simulated COI Power (initial WSCC base case) What the operators saw This event triggered an inter-area power oscillation and ended in a wide-area power outage in western US. 26

27 A number of these oscillations are showing up annually, and are a cause of growing concern. Alberta 0.45 Hz North South Hz East-West Hz California Desert Southwest 0.5 Hz These oscillations have caused transmission capacity to be derated by thousands of MW in the western interconnection, restricting the export/import of renewable power. System inertia is thought to be a factor. 27

28 Some renewable generators have low or no inertia. Traditional (thermal) power plants have inertia in the rotational mass of their turbine-generators. Some renewables exhibit traditional inertia Wind and some solar exhibit low or no inertia. If large amounts of renewables worsen the oscillation threat, how will the grid operator be able to respond? 28

29 Synchrophasor Measurements The Basis of the Smart Grid Transmission jfh 01/24/95 PRINCE RUPERT PEACE CANYON PSM DSM WILLISTON PPSM * SUNDANCE KEMANO MICA PPSM LANGDON VANCOUVER AREA PMU PMU DSM SEATTLE PPSM AREA PPSM DSM DSM GPS Satellite PMU DSM PPSM PORTLAND AREA PSAM PPSM PPSM CHIEF JOSEPH PMU PPSM GRAND COULEE PPSM HELLS CANYON HOT SPRINGS FT. PECK PMU PPSM COLSTRIP PPSM * SAN FRANCISCO AREA PMU SHASTA DSM MOSS LANDING PMU LOS ANGELES AREA BOISE PMU BURNS WECC MIDPOINT MALIN ROUND MTN PMU TABLE MTN SALT LAKE PMU * PSM CITY AREA PMU * DELTA PMU * DSM PMU DSM PPSM DSM LUGO PMU PSM DSM PMU PHOENIX PPSM AREA * MOJAVE PMU DEVERS HOOVER DSM PALO VERDE PPSM * PMU PMU PPSM PINTO NAVAJO PSM PMU * PPSM * CORONADO DSM PMU PMU FOUR CORNERS PPSM * PPSM MONTROSE PMU * ALBUQUERQUE AREA EL PASO AREA PMU DENVER AREA MIDWAY jfh Time-Stamp John Day Malin Summer L Slatt McNary Useful Real-Time Information PMU PPSM DSM HVDC Terminal Phase-Angle Measurement Unit (Macrodyne) Portable Power System Monitor (BPA) Dynamic System Monitor (PTI/Hathaway) PSAM PSM MEXICO Power System Analysis Monitor (BPA) Power System Monitor *Proposed installation Projected WSCC Monitors, 1995 PMUs (Phasor Measurement Units) Voltage - kv Data 425 Grizzly reactor #2 Grizzly reactor #3 Time Synchronous Data Ashe reactor Time - seconds Control Center Courtesy of EPRI Are like X-ray to MRI improvements in diagnostics capability. 29

30 Before Synchrophasor Measurements Traditional Real-Time Data Rate = Every 4-5 seconds Disturbances Power System Unobserved Response Addition of synchrophasor measurements throughout the western electric grid would create a dramatic change in speed and applications for situational awareness of the power system. 30

31 After Synchrophasor Measurements Synchrophasors 30/second ^ ^ Traditional Real-Time Data Rate = Every 4-5 seconds Disturbances System Planning System Operation Automatic Control Power System Unobserved Response Observed Response WECC Decision Processes Information Measurement Based Information System An unprecedented ability to see, know, plan and control for increased reliability and economic efficiencies. 31

32 CAISO, SCE, PG&E, and SDG&E Are Pioneering the Use of Phasor Technologies in California Compliments of CERTS

33 Mode Estimate: Example Poorly Damped Mode Alarm Threshold <3% damping Oscillatory Frequency (Hz) Alert Threshold <5% damping Damping Ratio (%) Photo courtesy CERTS 33

34 Other Synchrophasor Applications PMU Placement Strategies Angle/ Frequency/Voltage/Flow Monitoring, Trending &Alarming Mode Meter and Mode Shape Identification Steady-state System Baselining (e.g., based on angle separation) Applications for Renewables &DG Event &Performance Analysis Phasor Data Network &Storage System Dynamic Model Validation Smart Grid Applications Voltage Stability Monitoring Frequency Response Monitoring Dynamic Nomograms Improved State Estimation Advanced Remedial Action Schemes Dynamic State Estimation Planned Power System Separation System Inertia Monitoring Adaptive Protection Real Time Transient Stability Margin Wind Site Voltage Control Power System Restoration Congestion Management Oscillations Damping Linear State Measurement Interconnection Wide Dynamic State Estimation Wide Area PSS Stabilization 1 to 3 Years 3 to 5 Years > 5 Years LOW Box Colors: Necessary and Critical Critical with Added Benefits Moderate Need, Added Benefits Requires More Investigation Transient Stability Control Voltage Stability Control Wide Area Frequency Response Deployment Challenge MED HI 34

35 Some Other Smart Aspects of New Grid Technologies Expand situation awareness to automated control, intelligent protection and decision support O&M. Integrate operator intelligence with physical system actions, e.g., power flow control, restoration, congestion management, storage, demand response, distributed generation Enhance rate and level of understanding and acceptance by planners, policy makers, regulators and public Expand into system security from assaults, e.g., earthquakes, wildfires. Integrate the customer into the decision making processes 35

36 For additional information or discussion, contact : Merwin Brown Director, Electric Grid Research Voice: Fax: Merwin.Brown@uc-ciee.org And he ll find someone to help you. People tend to overestimate what can be accomplished in the short run but to underestimate what can be accomplished in the long run. Arthur C. Clarke 36