The Aderis ClearSky PLUS™ provides all of the interconnection functionality of the Aderis ClearSky™ Interconnection, as well as a fully automated inrush mitigation solution.
Utility distribution feeders radiate out from sub-stations, delivering power to customers (loads). Utility’s typically install line-voltage-regulators (LVRs) along the distribution feeder to help raise voltage as loads and distance from the sub-station draw voltage down. The LVR’s job is to act as an in-line step-up transformer to maintain voltage within acceptable tolerances.
Examples of typical loads include residential homes and commercial building.
Electrical loads are distributed on each phase, and along the distance or the distribution line, to distribute the loads evenly.
The act of balance loads across phases, and using LVR’s to ensure voltage is appropriate for this loads falls to the Utility’s engineering and planning teams.
When a moderately sized solar Facility is added to that same distribution feeder, say 5MW, the step-up transformers represent 5,000kVA of new load.
Although a solar Facility’s transformers are normally energized: from the inverters during the day, and the grid during the night; a loss of grid power will result in the transformers being de-energized.
Following a power outage, the initial energization (or magnetization) of 5,000kVA of step-up transformers results in a large surge of current draw (inrush current) that causes voltage to sag (rapid voltage change). Once magnetized, the current surge goes away, however the voltage sag can take an extended period of time to stabilize. The abnormal voltage on the distribution feeder can cause damage to electrically connected equipment and is considered and unacceptable power quality issue,.
Most likely you’v experienced a smaller example of these phenomenon in a building that has large HVAC units. When the compressors first start, the sudden additional load will cause lights to dim or fluorescent lights to flicker briefly. Both observations are the result of these power quality issues.
In a commercial application such as HVAC, compressors may be fitted with a “soft-start” device that stores energy in anticipation of the start-up, providing additional current reserves to remove the instant burden from the building’s electrical system.
Due to its size, there is no economical “Soft Start” option for a solar Facility, until now.
The Aderis ClearSky PLUS provides a “soft start” through a process we call “pre-energization”.
During a traditional energization event, the inrush current is caused because the step-up transformers need to magnetize, they need to be charged.