Gridco Systems, a provider of agile grid infrastructure solutions, announced that Hawaiian Electric Company has deployed the Gridco Systems In-Line Power Regulator™ (IPR) to enable integration of increasing levels of rooftop PV systems. The Gridco IPRs help maintain reliable power delivery within required voltage limits, supporting Hawaiian Electric's goal to triple distributed generation on its system by 2030.
Rooftop PV is an important part of the utility's clean energy portfolio and Hawaiian Electric leads the nation in installed PV per customer. However, this can present challenges.
For example, since rooftop PV systems provide little or no information to system operators, maintaining the steady 60 Hz frequency needed for reliable power delivery is increasingly difficult. A circuit that is saturated with PV also strains the grid as it adds electricity when demand isn't there. This causes voltage on the affected circuits to be higher than intended, sometimes sending power flowing back through transformers to substations not designed to support it.
"We work in concert with our planning groups within Hawaiian Electric to investigate new technologies and products, such as the Gridco Systems In-line Power Regulator, to better see and manage what's happening on the grid," said Dr. Dora Nakafuji, director of renewable energy planning for Hawaiian Electric.
In February 2015 crews installed pole-mounted IPRs on an overhead line identified by Gridco's modeling team, in collaboration with Hawaiian Electric engineers, as having voltage issues due to high rooftop PV penetration.
"With high-penetration PV on our lines, we see high voltage or back-feed conditions on some circuits," Nakafuji said. "The Gridco IPR allows us to see what is actually happening right at the pole that serves a cluster of customers. At the same time, it allows us to regulate voltage at that location as needed, based on how much power the PV systems are producing and power consumption by customers at the time of day.
"Gridco's IPR gives us real-time visibility to the edge of our grid," Nakafuji added. "We can actually get measurements down to the pole closest to the customer load where voltage issues might be occurring. This tells us very specifically what we need to do to manage for those conditions, without affecting everybody on the circuit.
"Distributed PV can impact a specific section of an electrical circuit without affecting the entire circuit. Traditional controls don't allow for that fine level of control, so raising or lowering the voltage on a line may help some customers but cause problems for others," she said.
"Maximizing the distribution system's PV hosting capacity at the lowest cost is a core function of an economically sustainable clean energy ecosystem," said Naimish Patel, CEO of Gridco Systems. "We are delighted to be working with Hawaiian Electric Company to help them meet their RPS targets while maintaining system reliability in a cost-effective way."