Electrification of Domestic Transport

Transcription

1 Electrification of Domestic Transport a threat to power systems or an opportunity for demand side management Andy Cruden, Sikai Huang and David Infield Department. of Electronic & Electrical Engineering Contact: a.cruden@eee.strath.ac.uk

2 Presentation Overview Review of Electric Vehicle Technology Development UK Vehicle Statistics Domestic Use of EVs Impact on the Power System Operation Opportunities for Demand Side Management. 2

3 Electric Vehicle Development Rapid Market Growth due to: i. Petrol price as the main driver (145.9p*); ii. Drop in costs of battery and electric motors; iii. Major car manufacture involvement. Incentive Schemes: i. UK: 43 million with 20 million to ii. iii. install local charging points; US: $7,500 Federal Tax Credit for EV purchases; EU: Tax Incentives. * source: petrolprices.com for Glasgow area, unleaded petrol price. 11/04/

4 UK Vehicle Statistics Licensed Cars 2010*: i. Total approx million cars ii. 89.7% as private owned; 8.1% as company owned. Domestic Car Use 2010**: i. On average, these cars are utilised only ii. 5.2% of the time for transportation. 94.8% of the time available for a secondary function, eg V2G power or to absorb G2V power (e.g. from wind) * source: Department for Transport, VEH0204, 14, April, dft.gov.uk/statistics/tables/veh0204 ** source: Time of Use UK Survey Report published in

5 UK Domestic Load Profiles Comparison of UK electric load profiles* Winter Peak * source: IEA Annex 42 report "European and Canadian non-hvac Electric and DHW Load Profiles for Use in Simulating the Performance of Residential Cogeneration Systems". April

6 Domestic Energy Consumption The average power demand from a domestic home is typically less than 2kW/day The average energy demand from a domestic home is approximately 20kWh/day Domestic peak demand can be up to 15kW Typical electric vehicles will have considerably more power and energy capacity on board to deliver required traction and range. 6

7 Commercial EVs - Cars Tesla Roadster G-Wiz Chevrolet - Volt Source: Lithium-ion batteries (375V dc, 53kWh) Top Speed: 125 mph Range: 220 miles Cost: ~$95,000 Source: Lead-acid batteries (48V dc, 9.6kWh) Top Speed: 50 mph Range: 48 miles Cost: ~ 10,000 Source: Lithium-ion batteries Top Speed: 99 mph Range: 300 miles* Cost: ~ 29,995** * The extended range of 300 miles includes the contribution from the petrol engine. Electric range is 50 miles. ** The price includes the UK Government plug-in electric car grant of 5,000. 7

8 Example - Honda FCX Clarity Hybrid Fuel cell/battery vehicle 100kW PEM FC 350 bar, 4kg H 2, compressed gas H 2 Refuelling time ~4 minutes Li-ion battery (Source: Could use the vehicle output to comfortably power your home Quick and easy to refuel 8

9 Potential problems Charging EVs in the home or on the street (charging posts) is convenient, but will have significant impact on the electricity distribution network. A better solution might be to shift charging demand from a number of electric vehicles to provide responsive loads. They could then be used for: i. Load levelling ii. iii. iv. Power flow control frequency support firming of renewables as feasible in the future 9

10 Power (MW) Uncontrolled charging Potential negative impact of uncontrolled EV charging Domestic PEV - 10% Domestic Peak! 0 Time (24hrs) 10

11 Demand Side Management Central Grid Industrial load Renewable Generation Industrial load Renewable Generation Domestic load Domestic load Domestic load Dual use storage off vehicle Dual use storage on vehicle Domestic load Dual use storage off vehicle Renewable Generation TP conference 18th April

12 Electric Vehicle as Responsive Load Fundamental infrastructure is being put in place, eg Smart Metering. Potential benefits for Distribution Network Operator (DNO) through reduction of operational and infrastructure costs. Feasible charging strategies: i. delay charging starting time with compulsory controlled ii. iii. electricity tariff signal to the end domestic user as charging EV at suitable tariff User preferable charging scheme 12

13 Electric Vehicle Charging Equipment (EVCE) EV chargers should: Prevent inadvertent disconnection Vehicle power supply must be un-energised until EVCE connected Must have ground fault interrupt detection to prevent vehicle chassis becoming live Must be interlocked to prevent vehicle operation whilst connected Must be unable to be used by other appliances (i.e. household appliances) Must make ground connection first and disconnect last before live phase(s) 13

14 EV Charging Levels U.S. Level 1 charging 120V, 60Hz, up to 24A, single phase Level 2 charging 208/240V, 60Hz, up to 40A, single phase Level 3 charging 480V, 60Hz, up to 400A, three phase (from Installation guide for Electric Vehicle Charging Equipment, Massachusetts Division of Energy Resources, 2000) 14

15 EV Chargers #1 On street Charging pillar with RFID access (Photograph Source: Cruden, EVS24, Stavanger) 15

16 EV Chargers #2 (Photograph Source: Cruden, EVS24, Stavanger) Home and on-street charging stations 16

17 EV Chargers #3 (Photograph Source: Cruden, EVS24, Stavanger) 3 phase, 400V, 125A supplied level 3 Fast-charger 17

18 Research Challenges Power system modelling Battery modelling Power system modelling (with renewables) Domestic car use probabilistic modelling Car use survey data Adopting future electric vehicle specs Technology Vehicle drive & integrated grid inverter Charging pillars & Grid standards for planning/protection etc Economics Commercial models Requires dedicated metering/billing 18

19 EV Research at Strathclyde Three current projects studying EV impact on the grid: EPSRC/E.On Transitions E.On Research Initiative 2007 Winner HiDef EV/DSM concept can be assessed by simulation modelling and monitoring data (i.e. electric vehicle trial monitoring data including domestic load profile and electric vehicle use profiles). 19

20 Probability Probability EV/LV Network Case Study Probabilistic car use modelling car leaving home Monte Carlo simulation modelling No. of houses in the case Initialisation Matrices Simulate no. of cars in each house MCS module simulates each EV daily travel pattern associated with no. of EVs EVs penetrations in each house 0.02 End of a day? YES Filtering unqualified data for each time step Use RGN to simulate domestic driving behaviour NO Data Acquisition from Matrices Time (24hrs) Random Number Generator YES Car left home in the data? NO :30 10:00 14: NO One car left home? Simulate period of time car away from home YES Random Number Generator Simulate journey length given by away period Calculate EVs battery charging demand Output data to EXCEL Journey Length given by Away period of time is calculated as Conditional Probability EVs battery charging demand is calculated without DSM scheme Journey length (10mins) 20

21 EV/LV Network Case Study Network GIS Information Low voltage single-line diagram All premises = 42 PV = 33 Length 194 m Phase Cable Phase A Cable Phase B Cable Phase C Cable Measuring point 53 10m 54 3-ph wiring = 0.10 inch PILC Single phase wiring = 25mm (AL) Hybrid 55 1 Pencraig North substation (Feeder 2) Measuring point m 23 3m m m m m 3m 34 25m m 1 38m 1 10m 13m 10m 39m 31m 10m 2 0m 23m 14m 13m 10m 5m 19m 20 38m m m 19 4m m 10m Link Box to Pencraig Estate feeder m m 27 8m 26 21

22 Power (kw) Power (kw) EV/LV Network Case Study Uncontrolled charging demand 300 Max charging peak! Charging profile with uncertainty factor 35 Uncertain peaks! Charging variations Time (24hr) domestic mean max min Time (24hr) mean 15th 47th 89th 22

23 EV/LV Network Case Study DSM as electricity tariff DSM as operation constrains 1400 Low tariff (10pm-7am) 1400 Peak shifting Delay charging domestic demand electricity tariff low price 10pm - 7am domestic demand shift EV load 23

24 Conclusions Electric vehicle market expanding due to high petrol prices, battery technology breakthroughs, and government incentive schemes. Concerns that wide-spread electric vehicle could lead to unacceptable burdens on the distribution network Huge potential of electric vehicles to provide responsive loads that could help DNOs meet operational constraints and reduce costs. Much research presently being undertaken to investigate the impact of electric vehicle charging on power distribution network. Future electric vehicle could play an important part in the network operations. Key unknowns concern whether vehicle users would embrace DSM/responsive load technology and constraints. 24