Reliable hybrid renewable microgrid and storage

“The time has come to focus on renewables and smart energy systems,” says Patryk Chaja of Polish research centre KEZO. Studies at the centre show that hybrid energy storage systems can balance out the inherent instabilities of renewable power production, making green power as reliable as fossil fuel-based power – with mature technology that is available today. DEIF ASC-4 and AGC-4 controllers are playing a key role in the KEZO microgrid by enabling control and communication between all system components.

It’s nice to know that when you flick the switch on your coffee machine, the power comes from solar panels. But on cloudy days, the power for your coffee, and for everything else, needs to be supplied in other ways. Increasing the share of renewables in the energy mix is an ideal solution as the world works to reduce GHG emissions and comply with the Paris agreement. However, the inherent instability of renewables means that the energy sector needs to find reliable ways of balancing energy systems, ensuring security of supply and stable voltage levels when renewable production cannot cope with demand – and when production surges.

Hybrid microgrids combining several renewables such as PV panels and wind turbines enable a relatively high overall percentage of renewable power. In order to ensure reliability and balance, such microgrids require intelligent control and the ability to store power in order to use it later. Several mature technologies for achieving this goal are currently being tested at Polish research centre KEZO. Using an energy storage system (ESS) with different types of batteries and managing the setup with DEIF controllers is producing very promising results.

The flow battery technology used in the VRFB is of particular interest to the KEZO research team. While the VRFB is comparatively large and has low energy density, it offers benefits that make it an interesting proposition for microgrid ESS applications: It is completely safe, as the vanadium electrolytes are not toxic or flammable. Also, the electrolytes do not degrade, giving the battery a very long service life. The 18-tonne 100 kWh VRFB at KEZO can handle at least 20,000 charge cycles without loss of capacity.

Each battery is managed separately, with individual power set points for each battery defined based on power consumption, current renewable production, and current energy prices. The setup uses DEIF AGC-4 Mains and ASC-4 controllers to handle battery control and communication. One of the most important benefits of the DEIF units is their ability to communicate with all batteries, helping KEZO staff develop, control and optimise the hybrid storage system control strategies.

Krzysztof Rafał adds that the DEIF setup provides a management system which enables control, coordination, and communication between devices such as PV installations, energy storage systems, and local loads. “It provides the functionality to control our production of energy and our exchange of energy with the grid,” he says. “The DEIF system can fulfil multiple functions for us. It makes our research easier!”
The two KEZO specialists cite the competent support offered by DEIF as a further source of satisfaction. “When some features were missing, DEIF were very cooperative in helping. Communication with DEIF was really very smooth. For us, the ability to communicate with the company is a big benefit,” remarks Weronika Radziszewska.

While hydrogen power or other technologies may one day become a feasible alternative to today’s renewable energy sources, wind and solar power generation combined with ESSes look set to be the best solution for secure and sustainable energy production for years to come. “We believe that we can change the energy system using renewable energy sources. The time has come to focus on renewables and smart energy systems,” concludes Patryk Chaja.