Plug-In Electric Vehicles (PEVs) and the Integration of PEVs with the Electric Grid Dave Tuttle Research Fellow & PhD Student Department of Electrical and Computer Engineering The University of Texas at Austin dave.tuttle@mail.utexas.edu Advisor ross.baldick@mail.utexas.edu
The Potential of Plug-In Electric Vehicles (PEVs) 70% of U.S. drivers travel less than 33 miles/day 50-70% lower cost per mile to operate on electricity compared to gasoline Recent enabling technologies: Lithium battery technology: driven by consumer electronics Computer Controls & Semiconductors: driven by computer industry PHEV architecture which provides no-sacrifices conventional-vehicle vehicle range Synergy with the electric grid Charge during valley when grid is underutilized & wind is strongest Centralized & remote emissions Massive energy storage potential for the grid Lower CO 2 emissions Reduced oil imports & reduced trade deficit (~50% from foreign oil)
Types of Plug-In Electric Vehicles (PEVs) BEV (Battery Electric Vehicle) PHEV (Plug-In Hybrid Electric Vehicle) erev (Series PHEV) Can Be Driven the same as today s vehicles Parallel PHEV Battery Size Very Large (24-53kWh) Large (~16kWh) Medium (4-12kWh) Range - Electric+Petrol Electric only: ~100-250 miles All Electric for Distribution 35 miles then 344 Miles on Petrol (=/> Conventional vehicle) Electric for 15 miles below 62mph & light acceleration Blended mode (=/> Conventional Vehicle) Charging -Home - Work/Public NoHome Charging Available? Home: Level-2 240V typically needed Work/Public charging needed if distance is beyond range Either charge at work/public or nota viable vehicle for this driver Home: Standard Wall Outlet sufficient but Level-2 240V can increase electrically driven miles Work/Public charging not necessary but useful Either charge at work/public or use as a conventional hybrid vehicle Key Advantages No internal combustion engine - Very low maintenance - No tailpipe emissions No range limitation Operates as BEV, then Hybrid No range limitation Smallest battery fastest charge
Source: Katherine Prewitt, SPP Source: Katherine Prewitt, SPP
An erev in real use in Austin, Texas Transmission Very Large (24-54+kWh) 3864 miles over 4 months on 1 tank of gas (typically every 2 months) -Further than the distance from New York City to Los Angeles - 8.1 gallons of gasoline + 1188kWh of electricity ($131 at Austin Energy rates) - ~3 miles/kwh energy consumption (35-42miles/gallon when running on gasoline) *Electricity = $0.11/kWh (U.S. Average =Austin Texas costs)
How the Electric Grid Works Generation Transmission Distribution End-Use Premise 2 nd Generation PEV - Coincident Charging - Emergency Load Control Load varies every second of every day Grid Operator adjusts generation to equal Load - Various sources of energy & types of electricity generators - Each with different capacities, ramp -rates, costs, emissions -Total electricity comes from combining numerous generators Grid Reliability Regions create a mesh network of sub-grids - Provides back-up (Reliability), scale economies (cost) Independent System Operators (ISOs) responsible for grid reliability and market functions
Intelligent PEV Charging Grid Operator (e.g. ERCOT) Aggregator Control Power Flow 4 th Generation PEV - Two-way PowerFlow Generation Transmission 2 nd Generation PEV - Ramp Rate moderation - Ramp elimination w/rapid charging Distribution End-Use Premise 2 nd Generation PEV - Coincident Charging - Emergency Load Control 1 st Generation PEV - Peak Avoidance -Off-peak Valley filling Research Goals: Modeling, control, and optimization of intelligent PEV charging Avoid aggravating peak demand, energy storage for load shifting Lessen ramp rate of thermal to compensate for Wind/other renewables Curtailable Load when large wind/generation output reductions occur Reduce curtailment (after transmission constraints removed) Challenges: System communication and control Across large numbers of distributed vehicles Varied Communications pathways & technologies Varied Grid-PEV interaction sophistication Across varied Utilities, Terrain, & Vehicles Cost, security, reliability constraints
PEV Home Charging & Transformers Coordinate PEV charging to avoid aggravating Peak Demand Align PEV charging with maximum Wind output 8-10x PEVs are a new type of load for the Electric Grid -- Large, Flexible, & intelligent (1-way powerflow) -- Grid Storage (2-way powerflow) Potential Benefits of Intelligent PEV charging -Avoid aggravating peak demand, energy storage for load shifting - Lessen ramp rate of thermal to compensate for Wind/other renewable- Res - Load Curtailment when large wind (or any) generation output reductions occur - Reduce curtailment (after transmission constraints removed) - Reduce distribution transformer upgrades if large scale PEV adoption
Energy Storage Additional Research Areas Compensating renewable generation with other sources SmartGrid Demand Response (DR) with equal or better convenience Human-Machine Interface (HMI) for Home Energy Management Systems (HEMS) Communications: latency/reliability/security of low cost DR & PEV coordination Weather/Meteorology: distribution of wind and solar resources - Ramps, Ramp Events, Tail events, confidence levels, advance notice Vehicles - Hybrid, PEV powertrains (programming w/mechanical understanding) - Battery management systems, Cabin HVAC systems & insulation Policy & Finance to reduce costs of renewable generation finance/construction/o&m Fuel selection efficiency/emissions/supply/infrastructure optimization per application Source: Source: Katherine Prewitt, Prewitt, SPP SPP