Electricity regulators in Puerto Rico issued final rules related to the installation of microgrids, moving it ahead of many states in terms of regulations for the technology.
The island's electric power grid was substantially damaged by Hurricane Maria, which struck the island in September 2017. More recently, the grid went down in April, disrupting electric service to the entire island.
Tanuj Deora, executive vice president and chief content officer of the Smart Electric Power Alliance (SEPA), said that “given the sense of urgency facing Puerto Rico with the upcoming hurricane season, SEPA applauds the Puerto Rico Energy Commission on its timely work on the final microgrid regulation, which reflects input from a broad range of stakeholders."
The new rules set up classes of microgrids, define types of electric power generation they can use and seeks to clarify the role of utilities and municipalities.
(Read the new rules on microgrids.)
Personal microgrids are intended to provide power to one or two consumers and may, with regulatory permission, provide excess energy and grid services to neighboring customers.
Cooperative microgrids are intended to serve three or more cooperative members, under two subcategories: small co-op microgrids of less than 250 kW or large co-op microgrids of more than 250 kW. As with personal microgrids, co-op microgrids may sell excess energy and services to others.
Third-party microgrids are intended to have owners or operators who sell energy services to customers under rates approved by regulators and set on a project-by-project basis. Owners may earn a rate of return for the first three years of operation.
At present, only off-grid personal and cooperative microgrids may be built. The island's utility, Puerto Rico Electric Power Authority (PREPA), must set interconnection rules for third-party microgrids. The regulatory body ordered the utility to set those rules within 120 days.
Battery Energy Storage
Battery energy storage may also play a role in bolstering Puerto Rico's electric power grid. Independent power provider AES Dominicana brought online 20 MW of energy storage arrays at two sites in the Dominican Republic in early 2017. The arrays helped to maintain grid reliability in September when Hurricanes Irma and Maria struck the island.
The two 10 MW arrays provided grid reliability services for the island by improving the efficiency and contributing to the stability of the Dominican Republic’s interconnected national electricity system (SENI).
In September, the Dominican grid operator directed AES Dominicana to keep the storage systems online to ensure grid reliability as Hurricanes Irma and Maria approached the island. AES said that both energy storage arrays during the storms performed more than double their usual amount of work.
During the storm the arrays went from a typical operating range of approximately +5 MW to -9.8 MW each, to a wider range of +9.8 MW to -10 MW each, effectively requiring an additional +/-5 MW each, or 10 MW total to maintain a balanced frequency.