Implementation of energy storage systems in the Azores Islands as a flexibility tool ...

Full presentation title: Implementation of energy storage systems in the Azores Islands as a flexibility tool to increase renewable penetration.

This abstract presents the results from the case study of using Energy Storage Systems on Graciosa island, in the Azores, as a flexibility tool to increase renewable integration.  The main results of the exploration of a grid with high renewable penetration and autonomous energy management will be presented.

INTRODUCTION

Led by Graciolica Lda, and supervised by Tractebel and INESC TEC, the project on Graciosa combined solar and wind generation, together with energy storage using lithium-ion batteries supplied by Leclanché SA, and the Energy Management System from Greensmith Energy, a Wärtsilä Company. The Graciosa island grid can address baseload supply requirements while accommodating fluctuations in output that are inherent to energy supplied from renewable sources, such as solar and wind. 

GRACIOSA MICROGRID

GRACIOLICA is a Hybrid Renewable Power Plant (HRPP) which enables 1MWp of solar (PVPP), 4,5MW of wind (WPP) and 3 Energy Storage Systems (ESS) units of 2,475MVA / 0,866MVAh at the Battery Power Plant (BPP).

CHALLENGES

Operating a grid with a high renewable energy penetration (5,5MWp renewable generation for a 2,3MWp load) imposes many problems to the microgrid that have not been seen on the main grid: 

Uncertainty and volatility of renewable energy sources;

Slow reaction times of diesel engines to the fast power output swings of the renewables;

No grid forming capabilities of PV and wind farm;

Spinning reserve requirements;

Primary and secondary frequency and voltage control;

Protection of a system with different assets and operation modes;

Transient stability during short circuit events with different assets and operation modes;

SOLUTION

In order to tackle these problems, an ESS sizing optimization study was performed resulting in the installation of a 7,425 MVA ESS. A powerful autonomous operating energy management system was developed by Greensmith to ensure a stable operation of the grid while maximizing the renewable penetration and not violating operational constraints. The Greensmith Energy Management System (GEMS) is able to control wind, solar, batteries and diesel generator units. The goals of GEMS operation are (in order of priority):

Maintain grid stability and security of supply (N-1)

Maximizing renewable penetration by forecasting load and renewable generation

Minimizing DPP operating cost taking into consideration different operational constraints of the diesel engines

Maintain grid power quality

RESULTS AND CONCLUSION

Graciolica Lda’s end client, local utility EDA, have reported an island renewable energy consumption of 57 % since last August and the reduction of around 17,000 liters per month at the DPP. The cumulative value at 100 % of renewable energy consumption has been of 28 days. Not only does this reduce the island’s carbon footprint, the hybrid island grid will also greatly impact the cost of energy going forward.

Overall grid reliability and resilience has been enhanced significantly, offering lessons that can be applied in larger-scale environments where utilities are looking to increase grid integration of distributed renewable energy resources, according to the project partners.