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August 4 (Renewables Now) - Hawaii's island of Maui is expected to become the first power grid of that size to run on 100% wind and solar on an instantaneous basis, said last week the US National Renewable Energy Laboratory (NREL), which is helping the island prepare for that moment.
Maui currently has almost 200 MW of wind and solar and is due to add 175 MW of solar-storage hybrid power plants through 2024, which will be enough to power its around 70,000 customers with no conventional generation for many hours of the year, explains NREL.
"No one has operated a power system the size of Maui's with 100% solar, wind, and batteries; to confidently operate any grid with 80–100% inverter-based resources on an instantaneous basis, there are important steps that we can take in the laboratory and on the field to prepare," said Andy Hoke, a senior research engineer at the laboratory.
According to Jin Tan, principal investigator of several NREL projects pursuing 100% renewable grid operations, inverter-based resources like wind, solar, and battery storage can provide all types of grid ancillary services by programing the controls, but system operators largely do not use them.
NREL has developed a software -- the Multi-Timescale Integrated Dynamic and Scheduling model (MIDAS) -- that allows grid operators to manage high-renewable systems by providing them with operational intelligence and advanced system analysis.
Thanks to MIDAS, Maui has been able to plan ahead for more renewables by modeling its operations under future low grid inertia, NREL said.
The laboratory efforts include a complete electromagnetic transient (EMT) analysis of the island which modeled its entire transmission system and was followed by simulation of snapshots of Maui's future system.
"We found that as Maui approaches 100% renewable operation, there are several options for ensuring grid stability," Hoke said. "Using synchronous condensers to stabilise, or even by programming grid-forming controls on a relatively small number of inverters, it is possible to stabilise a 100% renewable system on Maui, at least in simulation," the researcher added.
NREL is also leading a USD-3.6-million (EUR-3m) project to develop hybrid renewable power plant controls that combines stabilising controls with the MIDAS operational framework. NREL will first use a platform that offers a replica grid environment for Maui to develop and derisk the hybrid power plant controls at real power.
The project’s final stage will be a 60-MW demonstration on Maui's system.
(USD 1 = EUR 0.841)