Dynamic operating envelopes: what are they and why are they so important?

Dynamic operating envelopes provide upper and lower bounds on the import or export of power for a given time interval. Image shows rows of white letters and brown envelopes
12 November 2020

There is a seismic shift currently underway in our energy system as we transition away from large, centralised, fossil-fuel powered generators that typically result in one way flows of energy from where electricity is generated to where it is consumed.

Instead, we are seeing the emergence of a decentralised grid with the increasing deployment of distributed solar PV, residential and suburb scale battery storage, electric vehicles and controllable loads in the grid (referred to as Distributed Energy Resources (DER)). As we incorporate this DER into the energy system we are seeing the emergence of dynamic two-way flows of electricity in our electricity networks. Ensuring that these two-way flows of electricity do not breach the physical or operational limits of the electricity distribution networks is a critical concern and requires new and innovative approaches to managing our electricity distribution networks.

Enter dynamic operating envelopes, a mechanism for orchestrating and coordinating this huge influx of bi-directional energy flows into the grid. The evolve project, a $13 million ARENA funded research and demonstration project, centres around the use of dynamic operating envelopes. As part of this project the Battery Storage and Grid Integration Program recently published a report that delves into the calculation and use of dynamic operating envelopes.

Essentially, dynamic operating envelopes provide upper and lower bounds on the import or export of power in a given time interval for each of these distributed assets or customer connection points. Think of how neatly an envelope contains a letter, an operating envelope elegantly bounds the system behaviour within its safe operating capacity. It’s a fitting analogy.

Electricity distribution networks are modelled and analysed to understand their behaviour and performance and then operating envelopes are calculated using a variety of mathematical algorithms that take into consideration the voltage and thermal constraints.

It is the dynamic element of the operating envelopes that makes this mechanism so exciting. The ability to vary the upper and lower limits in short time intervals allows for a more intelligent use of the network’s hosting capacity. Factors that are taken into consideration when calculating dynamic operating envelopes include time, customer energy consumption or generation, and the weather. Operating envelopes are specified in time intervals designed to align with market intervals of 5 – 30 minutes over a forward 24-hour time period.

Another direct benefit of operating envelopes is the inherent increase in network visibility that it enables, providing a better understanding of how the network operates in near real time. The increased network visibility provided by the operating envelopes can arm the customer with near-real time information that assists them to participate in buying and selling electricity with energy and network services markets, ultimately allowing customers to earn more money from their DER investments. For example, for customers with both solar and batteries, the operating envelope signals indicate implicitly that it is better to defer charging of the battery until peak periods of energy generation (that is, during the middle of the day) when they would otherwise be paid the least for any energy that they export to the grid.

Operating envelopes are cost effective. Instead of building more physical assets (poles and wires) to accommodate more energy into the grid, they utilise smart software and algorithms to ensure the maximal safe use of existing network assets. Operating envelopes are simple to integrate into electricity network systems, operating as a series of software modules and algorithms. They can and are currently being implemented all over the country.

Dynamic operating envelopes represent a low-cost/high-value, simple to implement mechanism to help accommodate the huge influx of renewable energy from DER. Importantly they deliver a variety of benefits for network operators, regulators, electricity retailers and energy users. We are excited to share the results of our ongoing trials through the evolve project as we deploy these capabilities throughout Queensland and NSW over the months ahead.

Find out more about the evolve project here.https://bsgip.com/research/evolve/

This article was originally published by the Battery Storage and Grid Integration Program, hosted at ANU. The program is jointly funded by the ACT Government under the Renewable Energy Innovation Fund initiative and the ANU.

Established in April 2018, as an initiative of the ANU Energy Change Institute, the Battery Storage and Grid Integration Program consists of a collaborative community that researches solutions to real-world energy and associated systems problems in a holistic manner.