Introduce use cases for Energy Management

[jamesharrow]

Why is this content needed
Energy Management can be a complex area which is hard to understand from reading the spec and not necessarily something that move people understand the benefits of it for the consumer, the grid and the planet.

In order to attract manufacturers to support energy management use-cases in their appliances some basic intro will help break it down into simpler to understand concepts.

Who will benefit,
Appliance Manufacturers

Are you able and willing to create the content
Yes

Additional context
It looks like the current structure of the handbook may need to be extended with additional chapters - so may need a discussion on how best to do this.

I would propose the following outline content for energy management (it needs details and pictures to help):

• Energy Management use-cases

  • Our changing energy system : renewables and electrification of transport, heating and cooling
  • Avoiding using energy at peak times, using energy when its plentiful (e.g. solar)
  • For the consumer how does energy management help?
    • Reduces cost
      • Time of Use tariffs and Type of Use tariffs
      • Self-consumption (e.g. from local solar)
    • Reduces carbon footprint

• Alignment to government and other standards

  • EU Code of Conduct for Energy Smart Appliances
  • PAS1878

• Some important concepts - understanding the difference between Power and Energy

  • Power is instantaneous (measured in Watts), energy is the sum of power over time (measured in Watthours)
  • Using too much instantaneous power puts a huge demand on the grid, and can even blow the fuse
  • If you have too many high power devices switched on at the same time (e.g. 7kW EV charger, 5kW heat pump, 7kW induction hob), if all houses in the street did that then the substation could brown-out.

• System architecture using Home Energy Management Systems (HEMS) and Energy Smart Appliances (ESA)

  • Device Energy Management cluster capabilities:
    • Appliances can generate a forecast of their energy needs (e.g. a Washing machine knows its approximate power demand over time)
    • A energy management system can add up the peak demand and check that it doesn't exceed a total power budget and can ask the lower priority devices to reduce their power consumption or switch off temporarily. e.g. an EVSE could reduce the charging rate from 7kW down to 1.2kW, or a heat pump could reduce its compressor speed resulting in a reduced power consumption of 1.2kW, leaving the induction hob (a higher priority device) to use as much as it wants. Once the cooking has finished then the heat pump can be turned back up.
    • Equally if a home has solar power, then using weather forecast a solar PV system could forecast a predicted power forecast. The energy management system could encourage the EV charger to switch on and charge at a lower rate so it gets to use the excess solar that would otherwise flow to the grid.

• How exactly does it work?

  • Energy Reporting

    • Consumers want to know how efficient their appliances are, but also want to understand their bills. Devices can support the Electrical Sensor device type, which allows use of the Electrical Power Measurement and Electrical Energy Measurement clusters.
    • Apps or controllers can read the real-time power use of an appliance from its internal power and energy meter, or can track when the energy is being used.
    • If the consumer pays a different price at different times of the day (e.g. has a Time of Use tariff) then they can begin to understand how they can shift their energy use to a cheaper time of day to reduce their bill.
    • Where to find out more about the EEM / EPM clusters? [links to spec and SDK]

  • The Device Energy Management cluster is built into each ESA and allows the device to advertise its forecast

    • The forecast is a list of slots which allows the ESA to inform the HEMS what it intends to do, in terms of minimum and maximum power, nominal power, earliest start time, planned start time, latest end time, planned end time.
      • This allows a HEMS to potentially adjust the start time, using the StartTimeAdjustment command
      • If the ESA supports it, the HEMS can also ask the appliance to pause its operation, and then resume sometime later.

  • Some more capable devices (such as an EVSE, Heat pump, Battery Storage system) may be able to adjust their power consumption or power output. These devices may also support Power Adjustment, where the device advertises its power adjustment capability and allows a HEMS to request a turn up (increase in power) or turn down (decrease in power).

  • Summary key concepts:

    • It works for ANY electrically powered device that can be controlled can add the Device Energy Management cluster
    • The ESA is in control of what it does, and the user can opt-out using the Device Energy Management Mode cluster (e.g. a setting on the front-panel can allow the user to opt-out of any remote control by a HEMS).

• EVSE (Electric Vehicle Supply Equipment) Device Type

  • What does the EVSE (EV Charger) allow?
    • Reporting of EV charger state (and errors / faults), is the EV plugged in? Does the Vehicle want to charge? Is it charging?
    • Reporting of Power and Energy consumption (re-using the EEM / EPM clusters)
    • Reporting of charging session energy
    • Starting / stopping the EV charging session
    • Changing the charging rate
    • Setting of Charging preferences
  • Charging Preferences feature
    • As a consumer you may want the charger to automatically charge your vehicle at the cheapest time.
    • Unfortunately most EVs or EVSEs today cannot communicate the state of charge (i.e. battery percentage or range) of the vehicle.
    • However consumers may know how many miles they typically want to charge their vehicle by every day. e.g. it may only need 40miles of range for a daily commute, but may need more range for the weekend. So the user can simply set the added energy requirement (i.e. how many miles of range needed to be topped up) and when they want the charging to finish (e.g. 7am).
    • Often energy is cheaper overnight when there is less demand on the grid, so an intelligent EV charging solution can use information from the grid or the time of use charging to schedule when the EV should be charged.
    • The user can make use of their preferred App to edit their charging preferences, and let the charger work out the cheapest and greenest time of day to charge. It will let the user know what time it is planning to charge so that they can feel confident that when they get up in the morning the vehicle is charged appropriately.

• Is there some sample application which I can build my product with?

  • Link to the examples/energy-management-app in the SDK
    • It includes the following clusters:
      • Device Energy Management
      • Device Energy Management Mode
      • Energy EVSE
      • Energy EVSE Mode
      • Electrical Energy Measurement
      • Electrical Power Measurement
      • Power Topology
      • Power Source

[sammachin]

Accepted at PMTT meeting, 5th June 2024