Assessment of Variable Renewable Energy Grid Integration in Pacific Island Countries

TNEI, as part of a larger consortium, was commissioned to provide support to address specific operational concerns identified in the grid systems of a number of Pacific Island countries. These issues primarily related to dynamic stability, including frequency imbalance and loss of synchronisation, owing to insufficient spinning reserve and/or machines with inadequate Automatic Governor Control (AGC) and voltage regulator response. The impact of increasing renewable generation will exacerbate the issues faced by the electrical systems on the different islands, and it was the objective of the overall study to gain a better understanding of these issues and propose mitigating solutions, such as the use of energy storage to provide frequency support.

Under this assignment, TNEI performed detailed power system modelling and analysis on seven Pacific Island country networks to assess and understand their capability to accommodate increasing penetrations of variable renewable energy (VRE), primarily solar PV. An inception mission allowed the collection of comprehensive sets of data and information and detailed Digsilent Power Factory power system models were created and/or updated.

The models were built and then a tuning exercise was carried out to ensure the networks were behaving as expected. Following this, a comprehensive set of steady state and dynamic studies were performed to analyse the stability of the small island networks (particularly frequency response) in the event of credible contingencies. The networks were stress-tested to determine how much VRE they could accommodate before they became unstable. In a number of cases, battery storage was proposed as a potential mitigating solution, and other solutions such as network reconfiguration were also suggested.

stakeholder engagement mission was held at the end of the project with representatives from each of the utility companies on the different islands. TNEI presented the results of the studies and outlined the unique challenges for each network. A handover of the models was also performed, and instructions on how to run the study cases were provided to allow the in-country engineers to better plan and prepare their network for increased integration of renewables.