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EV Charging InfrastructureLesson 3 of 5FOUNDATION LESSON

Simultaneity, managed charging and demand limits

Connected load is the sum of charger nameplates.

READING TIME
14 minutes
OBJECTIVES
3 learning objectives
SELF-CHECK
3 check questions
INTENDED FOR
Fleet, property, utility, engineering and charging-operations teams

Educational lesson. Confirm project-specific requirements before application.

Integrated DC fast charger with a pedestal unit (product render)
Manufacturer renderIntegrated DC fast charger

01LEARNING OBJECTIVES

After this lesson, you should be able to:

  1. 01Calculate connected and managed charging demand
  2. 02Explain simultaneity without treating it as an arbitrary discount
  3. 03Design charging priorities around energy deadlines

02EXPLANATION

What is physically and operationally happening?

Connected load is the sum of charger nameplates. Operating demand is the power actually drawn at a particular moment. Load management can cap or allocate that demand according to site capacity, vehicle priority, energy need and departure deadline. It is a control strategy, not an assumption that vehicles will conveniently avoid charging together.

A good scheduler continually asks: which vehicle needs how much energy, by when, and what power can the site safely provide? It should also define behavior when communication fails, vehicles arrive late or the site approaches its demand limit.

  1. 01

    Sense

    Measure site demand, charger status and vehicle or session needs.

    Real-time kW
  2. 02

    Prioritize

    Rank vehicles by departure, route, state of charge (SOC) or operating importance.

    Service priority
  3. 03

    Allocate

    Distribute available power within electrical and charger limits.

    Setpoint/charger
  4. 04

    Recover

    Define safe fallback and rescheduling when data or communications fail.

    Fail-safe
READING NOTEIllustrative only. Managed limits must be validated against vehicle energy and departure requirements.
TECHNICAL VISUAL · SYSTEM-SPECIFIC MODEL

Connected load versus managed demand

A managed limit can preserve site capacity while charging energy is distributed over time.

Three vehicles connected. The earliest departure keeps full power and the others share what remains, so the site holds at its limit instead of reaching 150 percent.

  • AC power
  • Control and data
  • Power flowing, arrow shows direction
Illustrative arrangement, not a Metro Power project. Supplied equipment appears as Bescore renders and studio photographs of the equipment class; the grid, generation, buildings, vehicles and control equipment are drawn.
ENGINEERING VIEW · ILLUSTRATIVE

Load management: illustrative profile

normalized
Illustrative demand

Illustrative demand. Values are educational, not Metro Power project-performance claims.

04OPTIONAL ENGINEERING DEPTHEngineering reasoning for this learning pathThe same design relationship, checks and evidence apply across every lesson in this path.
DESIGN RELATIONSHIPAllocated charging demand ≤ verified site charging cap while each priority vehicle meets its energy deadline
  • Separate connected load from controlled demand
  • Include existing site peak and reserve margin
  • Respect vehicle acceptance, arrival and departure
ENGINEERING CHECKS FOR THIS PATH
  1. 01Build the single-line diagram from utility service to connector
  2. 02Run vehicle-energy and managed-allocation scenarios
  3. 03Test controller fallback when communications or site metering fails
FAILURE ANALYSIS
Observed signalPossible causeDiscriminating test

Site peak exceeds the enforced cap

Control latency, stale data or unmanaged charger

Compare meter, controller and charger timestamps

Vehicles miss departure targets

Allocation ignores energy deadline

Replay arrivals, initial state of charge (SOC) and priorities

PROJECT EVIDENCE TO COLLECT
  • Vehicle schedule and session traces
  • Site interval load and capacity study
  • Controller logic and fallback test

05WORKED EXAMPLE

Ten 60 kW chargers under a site cap

Ten DC chargers provide 600 kW connected load, but the approved charging cap is 240 kW.

STEP BY STEP
  1. If all are equal, initial allocation is 240 / 10 = 24 kW each
  2. Prioritize vehicles with earlier departure or greater deficit
  3. Reallocate power when sessions finish or acceptance falls
  4. Confirm the total energy delivered within each duty window
INTERPRETATION

A 40% demand ratio is not simply assumed; it is actively enforced and tested against the mobility requirement.

06COMMON FAILURE OR MISCONCEPTION

“A 40% simultaneity assumption guarantees demand will stay at 40%.”

CORRECTION

Only an enforced load-management limit or validated operating behavior can control demand. An unsupported factor is not protection.

RETRIEVAL PRACTICE · 3 QUESTIONS

Check what you can explain without looking back.

Choose an answer and report your confidence. The confidence signal is stored only until you submit this page.

OBJECTIVE · Calculate connected load

Ten 60 kW chargers equal:

How confident are you?
OBJECTIVE · Control demand

What keeps demand below a defined cap?

How confident are you?
OBJECTIVE · Preserve service

What should guide allocation?

How confident are you?
Answer every question and confidence prompt.

08SOURCE NOTES

Sources for further study.

International references support further study. They do not replace Philippine laws, regulations, utility requirements or project specifications.

  1. 01Electric Vehicles for FleetsUS Department of Energy Alternative Fuels Data Center

    Fleet planning, equipment, operations and training considerations.

    Open source ↗
  2. 02State and Local Planning for EV Charging InfrastructureUS Department of Energy Alternative Fuels Data Center

    Charging infrastructure planning framework.

    Open source ↗
  3. 03Open Charge Point ProtocolOpen Charge Alliance

    Current OCPP versions and capabilities.

    Open source ↗
Read the complete technical paper

NEXT IN THIS COURSELesson 4 of 513 minutes

Site works, software and charging operations