Australia is in the midst of an energy revolution. The growth in solar power, energy storage and smart control technology has the potential to change the way our society produces, uses and sells energy. To help us prepare for this future, AusNet Services is trialling Australia’s first mini grid in an established community.
A mini grid is a local energy system made up of individual customers that have the capability to generate, store and export power. A control system enables these customers to operate as a unified energy community. Most mini grids remain connected in some way to the larger network.
As shown in the diagram, the project involves powering 14 homes in a suburban street with a combination of (1) solar panels, (2) 10kWh storage batteries and (3) the main power grid.
Each residence is equipped with advanced energy management, communications, monitoring and safety systems. This enables individual participants to capture, store and optimise the use of both solar and grid energy to achieve aims such as reducing their power bills or increasing their use of renewable solar energy.
In addition, all 14 homes can operate as a unified energy system, i.e. a mini grid. Energy can be shared between homes via the mini grid network (4), while the entire mini grid can interact with and support the main power grid. For the majority of the time the mini grid remains connected to the main power grid, but it is also designed with the ability to disconnect and operate independently for short periods.
One of the most technically-advanced components of project is the stabiliser (5), which allows the mini grid to operate independently of the main grid. The stabiliser is a smart battery storage system that smooths out short term variations in energy supply and consumption across the mini grid by either delivering or absorbing power. The stabiliser is unique in that it operates using renewable and stored energy, whereas typically, mini grids use a large diesel generator to ensure stability when operating independently.
The stabiliser is connected to the main power grid by a switching device (6). It uses this device to control the transitions of the mini grid to and from the main power grid.
The entire mini grid is managed by a cloud-based software platform called MicroEMTM (7), developed by our project partner GreenSync. This software is in constant communication with the power system at each home, as well as the stabiliser and switching cabinet. The software platform monitors and analyses data and sends alerts and notifications to the 24-hour operations team, ensuring safety and applying the mini grid operating parameters. This software will evolve to control the mini grid in a variety of ways.
The diagram below shows the main components of the Mooroolbark Mini Grid.
AusNet Services will run three main scenarios that will explore different aspects of the mini grid and how it interacts with the main grid while accounting for customer and network needs. These scenarios are:
#1: Grid Interactive. Each house operates in grid connected mode, using solar power, batteries and the grid to create efficient power storage and consumption, as well as supporting the network by reducing peak demand, smoothing power flows and improving power quality.
#2: Secure Power. Each house operates in off-grid mode, using the individual solar power, batteries and demand/consumption management approaches to optimise energy use.
#3: Energy Island. The mini grid community operates independently of the main grid, using power sharing to balance energy generation and consumption in a stable, secure way.
The electricity grid is shifting from being a one-way pipeline that carries energy from large power stations to the customer, to a multi-directional web that supports a wide range of renewable and distributed energy sources. Customers are already becoming active participants in the power grid.
This situation brings considerable challenges to network operators, but could also provide major community benefits.
Each of the mini grid scenarios will give us a better understanding of how to adapt to a future in which we support our customers’ diverse energy choices, while operating our network as efficiently as possible.