Beaverton School District Transportation Resiliency 2024-0884
Prepared for:
Beaverton School District
Portland OR, 97204
100 SW Main St. Suite 1600
August 16,
Interface Engineering Inc
Beaverton School District Transportation Resiliency August 16, 2024
1.1 SUMMARY
A. The intent of this report is to analyze existing utility data of currently installed electrified bus charging installations so that infrastructure needs could be determined and a plan put in place that would allow the EV busses to still be operational in case of power outages.
2.1 LOAD ANALYSIS FOR 8-LEVEL 2 CHARGERS
A. A nearly complete year of monthly consumption data was provided for a site with 8-Level 2 chargers. See below:
B. According to the metering data, the majority of power consumed per day is on-peak which means shifting power consumption within the bus charging software to the nighttime hours could have significant energy cost savings. Based on the School District’s Utility rates time based charging scheduling would save approximately $1200/year.
C. The heaviest EV charger loads per school day were observed in the month of September. Buses during this month used approximately 56% of their median capacity per school day in September which suggests that off peak charging may be largely possible using software without the use of a microgrid. See below for kWh consumed per charger per school day:
Beaverton School District Transportation Resiliency August 16, 2024
D. If a BESS system was selected for 8 Level 2 EV charger site, based on the power consumption per school day it, the BESS would need to be in the 1MWh range to be able to handle one school day of power consumption in the month of September.
A. Only three months of consumption data was provided for a site with 20-Level 2 chargers and 30Level 3 chargers. The first two months appeared to be low in consumption based on the data observed from the other site. As such only the third month was used for analysis. See below:
Beaverton School District Transportation Resiliency August 16, 2024
B. According to this metering data as well, most of the power consumed per day is on-peak which means shifting power consumption to the nighttime hours could result in significant energy cost savings. A possible yearly savings amount could not be determined because of the lack of data.
C. In order to extract the average and maximum daily power consumption for the level 3 chargers from the data, the 8-Level 2 chargers was used to subtract out probably monthly consumption of the level 2 chargers so that the level 3 chargers could be isolated. See below for total kWh consumed per charger per school day:
D. In May, assuming Level 2 charger use tracked similarly to the 8-level 2 charger site, the above suggest up to 362kWh/day/level 3 charger which is 6 hours of full speed charging. Upon further discussion with the District we learned that approximately two busses are charged at each high speed charging station per day which is consistent with this result.
E. We only have one comparable month to work with, but what we have indicates that May, being a relatively light month, would only have required 1.2MWh capacity BESS to power the entire system for one day. Unfortunately, September required 3x as much power at the 8-level 2 charger site. For worst case scenario reliability, the new site will require a 4MWh system.
Beaverton School District Transportation Resiliency August 16, 2024
A. Photovoltaic panels mounted on carport structures at parking lot were simulated using the Helioscope design software and HomerPro to determine the maximum practical system size to plan for in the electrical distribution system and to find out if Net Zero power consumption was feasible.
B.
C. Estimated loading was modelled on a monthly basis based on the load analysis described above. Annual energy anticipated to be purchased from the grid is 779,157 kWh and the annual energy anticipated to be sold to the grid is 192,074 kWh.
D. The PV System size required to achieve Net Zero is approximately 800kW
E. The electrical infrastructure to connect PV to Micro Grid Switchgear.
1. Provide a 400A, 277/480V panel, 3-phase, 4-wire PV aggregation switchboard for new PV panels at Parking.
A. A new 480V, 3-phase battery energy storage systems (BESS) was evaluated as a possible means of support of the facility in a power outage and as a method for extending generator runtime in combination with PV.
B. Basis of Design: ABB PSTORE Series.
C. The total storage capacity was analyzed to determine the battery capacity required for a single 70% charge of each bus using the Level 2 charges and two 70% charges from each of the Level 3 charges. A 500kW rated 4MWh battery system is required to meet that requirement.
D. All analysis of the BESS size and capacity came back as infeasible. The most efficiently sized battery system due to maintenance and replacement costs over a 30 year period increased net present cost of the project by over 14 million dollars even when an initial cost of $0 was analyzed using HomerPro.
A. The new electrified bus charging station will require 18 level 2 EV chargers and 2 level 3 EV chargers. In order to ensure functionality of the system in the event of Utility power failure, a fully
Beaverton School District Transportation Resiliency August 16, 2024
interconnected microgrid with 24-hour backup will be planned for. Microgrid assets will have the capability of being remotely controlled by a microgrid controller to keep all buses online during a power failure. Provisions for a temporary generator shall form part of the base requirements. A transformer will drop the voltage down from 277/480V to 120/208V to a nearby distribution panelboard to feed the level 2 EV chargers while the level 3 fast chargers will have dedicated circuits from the main switchgear.
A. The main switchgear will be a 1600A 480Y/277V 3-Phase 4 Wire switchgear fed from the utility through a Terminal and Current Transformer cabinet. The switchgear shall have provisions for future alternate sources and feature integrated metering and motorized breakers.
5.3
A. All EV chargers are to be fed from the main switchgear. The 2 level 3 fast chargers will be fed directly from the main switchgear while the 18 level 2 chargers will be fed from the downstream central distribution panelboard.
B. EV chargers to be controlled by remote power monitoring software to allow for all chargers to operate simultaneously without disruption to the power supply.
1. The Level 3 charger basis of design is the ABB Terra 184 which is a 192kVA unit.
2. The Level 2 charger basis of design is the Clipper Creek CS-100 which is an 16.6kW unit.
5.4
A. Provisions for a temporary generator will be included to allow for a separate source of electricity to be present for any unforeseeable reasons utility power is not available. The temporary generator three way transfer switch will be capable of accommodating a 500kW temporary generator. If utility power is not available for an extended period of time the temporary generator can allow the buses to charge normally.
6.1
A. A paralleling capable 500kW-277/480V-3Ph-4W genset complete with a sound attenuating enclosure designed to operate on loss of Utility power only will be provided.
B. The generator will be interlocked with the utility feed to never allow the generator to back feed onto the grid in the event of Utility power loss.
Beaverton School District Transportation Resiliency August 16, 2024
A. The final form Renewable Energy Microgrid (REM) proposed for Beaverton SD as depicted in the attached single line diagram is designed to operate in either blue sky or islanding mode. In blue sky mode, the utility grid is functioning normally, and all EV Charging loads are operating as though connected to the grid in a conventional manner. Behind the scenes, the centralized microgrid controller will be utilizing the solar generation and battery within the REM to minimize electricity costs via peak shaving. This includes centralized management of PV assets, generator and battery energy storage systems (BESS).
B. When the grid fails, the main switchgear automatically trips the Utility feeder and the microgrid controller reconfigures all REM components to operate in islanding mode.
C. The REM proposed for the site is sized to carry the normal operating load of the EV Charger system in the month of September for a multiday outage without the need for refueling which is the month observed to require the most energy consumption.
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Report
Project Name Beaverton School District 5th St
Project Address 10615SW 5th St, Beaverton, OR 97005
Prepared By Joe
Schmid
joes@interfaceeng com
Monthly Production
System Metrics
Design Design 1
Module DC Nameplate 2442kW
Inverter AC Nameplate 2165kW Load Ratio: 113
Weather Dataset TMY, 10km grid (45.45,-122.75), NREL (prospector)
Simulator Version 8364a100fc-f1b4638b98-d2a335f13f93b1b2640f
Project Location
Sources of System Loss
ACSystem:0.5%
Inverters:2.0%
Clipping:0.0%
Wiring:0.2%
Mismatch:3.2%
Description Condition Set 1
Weather Dataset TMY, 10km grid (4545,-12275), NREL (prospector)
Solar Angle Location Meteo Lat/Lng
Transposition Model Perez Model
Temperature Model Sandia Model
Temperature Model Parameters
AC System Derate 050%
Characterizations
Component Characterizations
Uploaded By Characterization
TSM-PD14320(May16) (Trina Solar) HelioScope Spec Sheet Characterization,
Inverters Sunny Tripower 24000TL-US (SMA) 9(2165 kW)
Strings 10AWG(Copper) 45(5,0034 ft)
Module Trina Solar, TSM-PD14320 (May16) (320W)
763(2442 kW) Components
Field Segments
Field Segment 1
Field Segment 2
