Close to the Metal Dense Area EVSE Network Considerations and Constraints Dorrier Coleman TEQ Charging
Who We Are Intelligent EV Charging Dorrier Coleman -Smart charging interface for all chargers CTO, TEQ BSCmpE Georgia Tech -”Time based multiplexing” optimization of charging - Listening to user’s charging requirements and providing decision making information and charging sessions seamlessly
Why This Is Useful Anecdotal traction in the MFH and Workplace spaces ● ● Result of significant cooperation with building managers, owners, and electricians ● Multiple technologies in many kinds of buildings
Defining Dense Area for EV Network Design Infrastructure Large structures ● ● High population densities Limited parking ● Many EV’s per parking area ● Economics ● High land values ● Pressure on revenue performance for space use and improvements Image source: Wikimedia Foundation
Pressing Issues to Address* Infrastructure Apartment Reliability Costs and Workplace Killing installations Unique challenges From is it available to with high price tags and unfulfilled is it broken, the and few means of stakeholders make status of a lot of control for slow growth infrastructure is unknown *Shamelessly stolen from Jun 2018 EPRI Survey
Pilot Report ● 32 Pilots ● 3 phases Hotels, Apartments, Workplaces ● ● Access Control Payment ● Power Management ● ● Web based driver and owner interaction
Pilot Phase 1 example: Small Office 4 Story building ● ● Built in the 60’s ● Very short distance from power panel to chargers ● System able to use Wifi, Zigbee, Ethernet, CAN, Modbus Unable to get consistent wireless connection ● Forced to fall back on ethernet due to rf properties of walls and ceilings ● Cat 5e pulls very expensive ●
Pilot Phase 2 Example: B&B 3 Story building ● ● Built in the 1910’s ● Mixed brick and stonework, very thick wooden ceilings and floors ● System used cellular modem and controls transformers Avoiding penetrations and separate communication conduit successfully ● controlled installation costs Very robust system, but very bulky ●
Pilot Phase 3 Example: Large Apartments ● 6 Story building, mixed use ● Built 2000’s Challenging cellular environment ● ● Substantial length and width to building ● System used cellular modem, CAN communication ● Challenging RF environment overcome with larger antennae Multiple cellular modems placed to avoid ● very long control wire runs
The Building Difficult Penetrations ● Long Pulls ● ● Little Panel Space ● Poor RF environments
Notes on Sources of Cost Two communications strategies: wireless and wired Key factors in common: ● Distance ● Number of Penetrations Construction Materials ● Image Source: Wikimedia Foundation
A Microeconomics of EVSE Growth 1. Commercial property owners are motivated by payback period (They probably don’t use discounted payback period) PP = EVSE Price + Installation + Setup Charging Revenue - (Electricity costs + Operator fees) 2. PP <= 2 yrs
The Urban Market Distribution Install Cost - 2* Annual Revenue Stream = 0 Or PP <=2 In other words, the harder installation is the fewer buildings will buy
Commercial Property ● Ugly Install Region ● Older buildings tend to be harder to penetrate due to construction techniques.
New Construction Issues New construction ● is getting larger ● This trend tends to complicate costs
New Construction Issues Signal loss is higher in thermally efficient construction ● “ Experimental results, such as those collated in Report ITU-R P.2346, shows that, when characterised in terms of entry loss, buildings fall into two distinct populations: where modern, thermally-efficient building methods are used (metallised glass, foil-backed panels) building entry loss is generally significantly higher than for ‘traditional’ buildings without such materials. The model therefore gives predictions for these two cases. ” -ITU Rec. P. 2109-0 (06/2017) ● Thermal barriers likely to exist around interface between building interior and parking
Multifamily Housing MFH also tends to be ● older Source: 2000 US Census
MFH New Construction MFH construction is ● trending towards larger Buildings. Source: US Census Bureau
But is this relevant? Is cost just a manufacturer and installer concern? ● There are path dependency and network effects that make guidance critical ○ Stakeholder input is needed now. ● ○ Installations are cost intensive and therefore very “sticky” ○ (Economic) utility is distributed among many parties, not all of whom are involved in every buying decision ○ Marginal cost of additional utility is very low before install and very high after ○ Substantial danger of becoming locked into sub-optimal path dependent possibilities ● Standards need to be physical layer agnostic but physical layer considerate
Local Charger Network Model The Internet Interfaces Local Links EVSE EV BMS ISP’s Other automation EV Telematics (lights, etc.) Cellular Wifi Data <GHz radio Utility DR Networks EVSE proprietary User devices Ethernet
Kinds of Communications and Constraints Requirement Bandwidth requirement Latency requirement Equipment Status Reporting Low Medium Demand Response Low High Access control/payment Low High Charge Session Telemetry High Low
Site Local Network Resources Site EVSE / User Infrastructure Operator ● Wifi ● Cellular Modems ● EV Telematics Ethernet (LTE-M especially) User cell phone ● ● ● ModBus ● Sub-GHz Radio CAN Bluetooth ● ● Grid Demand New Com. Wire ● ● Response Sub-GHz Radio ●
Potential Directions for Standards Differentiate between high bandwidth and low bandwidth interactions. Keep ● high bandwidth interactions off the local charger network where bandwidth is expensive. ● Differentiate between time sensitive and time insensitive interactions. Allow time insensitive interactions to take place over links that aren’t guaranteed to be connected. “Yes and” is critical. The cost effective way to implement a local charging ● network is as diverse as the buildings themselves.
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