The value of field experience
Bardzour PV plant on La Reunion. (Photo: Saft)
SEV has deployed a 2.3 MW ESS to maintain grid stability for the Faroe Islands. (Photo: SEV)
Experience in the field has shown that there are a number of factors that lead to high performance and a long and predictable life for a Li-ion ESS.
Good thermal management is the most important factor, ensuring that the temperature is consistent across the entire ESS. By minimizing temperature variation, the cells and modules experience a constant rate of aging. In turn, this allows for precise prediction of battery performance over its lifetime.
Other important aspects are to ensure accurate measurement of state of charge (SOC), good SOC management, and ensuring high energy efficiency of the battery system itself as well as the power converter and auxiliary systems such as cooling plant.
Together these extend the lifetime of the ESS, enhance performance and optimize the total cost of ownership.
By taking into account the many variables experienced in real-world operation and integrating these into our own EMS and modelling, Saft has engineered ESS installations optimized for a number of renewable energy applications as shown in these two examples.
9 MWh ESS for La Réunion
The ESS installed at a 9 MWp PV plant at Bardzour on La Reunion in the Indian Ocean (see figure 2) provides power shaping to inject power into the grid at a constant 40 per cent of the plant’s peak power capacity. It also provides primary reserve at 10 percent of peak power for up to 15 minutes as well as providing voltage support.
Modelling identified the optimum size of the ESS as 9 MWh energy storage capacity in the form of 9 containerised systems.
Optimizing wind power for the Faroe Islands
SEV, the Faroe Islands utility, has commissioned Europe’s first fully commercial Li-ion ESS operating in combination with a wind farm. The 2.3 MW, 700 kWh containerized solution is helping to maintain grid stability so that the islanders can capture the full potential of their new 12 MW Húsahagi wind farm.
SEV’s key aim was to overcome the short-term variations, lasting from seconds to minutes, that result from the variable nature of wind generation. A simplified model was used to calculate the power and energy for smoothing at the wind farm level. The most critical requirement was to achieve a ramp control that ensures the combined power flow of the wind turbines and the battery at the point of connection (POC) must not vary by more than 1 MW.
Lessons learned and conclusions
Owners and operators of power plant need to have complete confidence that their ESS is both consistent and predictable. To achieve this, it is essential to recognize a number of key considerations:
- Operational profiles are complex and multi-functional
- Sizing is an iterative optimization process
- System performance relies on consistent, predictable ESS performance
Authoring Information:
Michael Lippert, business development manager for Saft’s Transportation, Telecom and Grid (TTG) division.