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Load shedding is the intentional, temporary reduction of electrical power supply to certain appliances and/or circuits. This is done to reduce electrical consumption and is a cost saving measure. Load shedding helps to balance supply and demand, ensuring the stability of the overall electrical system during times of high demand or when there are issues with power generation.

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https://www.youtube.com/watch?v=VvCU27lj3rU

Why use a Script for Load Shedding?

Using a script running on a Shelly Pro 3EM has a lot of advantages, especially when combined with various other Shelly relays. Scripting can offer a highly customizable and extremely efficient way to accomplish load shedding. A script either from the repopulated Shelly library or manually entered is used to create a system where you can dynamically control and shed loads based on certain conditions, such as high energy consumption or demand.

Prerequisites

Info

These devices will be used to gather the consumption data required for load shedding

PM devices can be used to gather additional consumption data and control circuits during shedding.

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Info

These devices will be used to control various loads during shedding.

Steps to Setting up Load Shedding

1. Setting Up Shelly Pro 3EM

Wire and Configure the Pro 3EM

  1. Install and Configure: Install the Pro 3EM per the diagram below to monitor the energy consumption of the entire home.

Info

In scenarios where CT-B is not used, it is advised to repurpose it to cover Neutral. This requires recalibrating in the device’s settings.

Info

Standard split single phase electrical systems in North America will only use CT-A and CT-C to cover incoming feeds.

Note: Shelly Pro 3EM must use the C terminal connection to power the meter’s microcontroller, so CT C must always be used. Either CT A and CT B can be used for the other phase.

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Note

Terminal C must be connected to line voltage to power the microcontroller of the Pro 3EM.

Legend

Terminals

Cables

A

Phase A input

LA

Phase A live (110-240 V) cable

B

Phase B input

LB

Phase B live (110-240 V) cable

C

Phase C and power supply input

LC

Phase C live (110-240 V) cable

N

Neutral terminal

L

Mono-phase live (110-240 V) cable

IA

Phase A current transformer input

N

Neutral cable

IB

Phase B current transformer input

Current transformers

IC

Phase C current transformer input

CTA

Phase A current transformer

IN

Neutral current transformer input

CTB

Phase B current transformer

CTC

Phase C current transformer

CTN

Neutral current transformer

  1. Connect to Network: Using Shelly Smart Control, connect the Pro 3EM to your network.

Info

Shelly Pro 3EM supports both Wi-Fi and Ethernet

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  1. Shelly Cloud (optional): Add Shelly Pro 3EM to a Shelly Cloud account for remote access.

2. Set Up Additional Shelly Relays

  1. Install Shelly Relays: Install Shelly relays to control the specific loads you want to manage.

Info

Product Specific installation information can be found at the Knowledgebase

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  1. Connect to Network: Using Shelly Smart Control, connect the Pro 3EM to your network.

Info

Shelly Pro 3EM supports both Wi-Fi and Ethernet

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  1. Shelly Cloud (optional): Add Shelly Pro 3EM to a Shelly Cloud account for remote access.

3. Adding the Load Shedding Script to the Host Pro 3EM

Note

The below steps should be done on a computer using control.shelly.cloud instead of using the App on a mobile device.

  1. Navigate to the Scripts Menu: Shelly Smart Control has a section for Scripts for each compatible device. For Load Shedding we will use a Shelly Pro 3EM. With that device select click on the { } Icon.

  1. Click Open Library and Select the Script: On this screen we will select; Load Shedding with Shelly Pro 4PM and Pro 3EM. Expand this option and press the button labeled Insert Code

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  1. Name the Script: At the top of the screen give your script a name.

  1. Setting the Devices to be Shed: The devices to be shed are specified under first_to_last_to_shed

Info

This is an ordered list defining how and when specified devices will be controlled. This list also specified the on and off url’s for the devices.

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Note

You are not restricted to using only 5 devices; you can use fewer or more. The number 5 is simply used as an example here. Keep in mind that the higher-numbered entries (4 and 5 in this example) are considered the most important circuits—they will be the last to be turned off and the first to be turned on.

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  1. Configuring the Shedding Trigger Parameter:

    1. max_before_shedding

Info

Ensure that the value assigned to max_before_shedding is greater than the value set for min_before_re_adding

Note

A 10% difference should be considered the minimum, but a 20% difference is preferable.

Info

The larger the gap between the minimum and maximum values, the less "churn" you'll experience. Providing sufficient space between these values will enhance the efficiency of your load shedding.

  1. Configuring the Reading of Devices:

    1. min_before_re_adding

Info

Ensure that the value assigned to max_before_shedding is greater than the value set for min_before_re_adding

Note

A 10% difference should be considered the minimum, but a 20% difference is preferable.

Info

The larger the gap between the minimum and maximum values, the less "churn" you'll experience. Providing sufficient space between these values will enhance the efficiency of your load shedding.

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  1. Configuring the Polling Frequency:

    1. poll_time

      1. Minimum interval between executing normal on/off steps

    2. short_poll

      1. Interval after toggling on a device assumed to be already on

Info

The minimum value for poll_time should be 60. During "turn on" cycles, ensure you allow sufficient time for inrush spikes to stabilize.

  1. Set Logging Parameters:

    1. logging

      1. will populate the Activity Log

Info

By default logging is set to false meaning it is off.

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  1. Set Simulation Parameters:

    1. simulation_power

      1. Set this to manually test in the console

Info

White this can be a helpful tool for troubleshooting, care should be taken to ensure this is set to 0 during normal operation.

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  1. Saving and Executing the Script:

    1. Click the Save Button in the top right next the the Script Name and Play Button

    2. Click the Play Button in the top right next to the Script Name.

5. System Testing

  1. Simulate High Load: Increase the load to trigger the thresholds.

  2. Verify Script Actions: Check if the Activity Log to verify the Load Shedding Script is executing the defined commands.

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Info

Adjust Settings: After a satisfactory system test setting should be fine-tuned in regard to the thresholds and actions based on your requirements.

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By following these steps, you can effectively use a Script with Shelly Pro 3EM and various Shelly relays to implement load shedding, helping to manage and reduce energy consumption dynamically.