“The remote adjustment and mutual support function has commenced seamlessly, resulting in the normalization of voltage levels within this distribution transformer area,” said an operations and maintenance engineer on August 22, as the No 3 transformer area in Jiaowu village, Xinchang town, Quzhou city, East China’s Zhejiang province, and the adjacent No 3 transformer area in Guotang village, were successfully interconnected in a dynamic manner. This connectivity facilitated the transmission of renewable energy generated in Jiawu to Guotang.
Hong Heqiang, a member of the State Grid Zhejiang subsidiary’s staff, elaborated, “During favorable weather conditions, if the photovoltaic equipment in one transformer area generates excess power beyond local demand, causing the terminal voltage to surge, the adjacent transformer area can efficiently absorb this surplus solar energy through our flexible interconnection device. This ensures a stable power supply for both areas.”
As the summer season posed peak-time challenges to the grids, the operations and maintenance personnel of State Grid Zhejiang subsidiary conducted inspections of the power transmission lines. During one such inspection, they discovered that the transformer arrester in Guotang village, Xinchang town, had been severely damaged by lightning strikes and required immediate replacement. Traditionally, such maintenance would necessitate a power outage across the entire distribution transformer area, a process that could extend beyond three hours, inconveniencing over 150 villagers.
But with the inaugural low-voltage flexible interconnection device between the No 3 transformer in Guotang and the No 3 transformer in Jiaowu, which was commissioned in July, things are different. This groundbreaking technology not only orchestrates flexible interconnection equipment and distributed energy storage resources but also enables seamless power supply transitions during scheduled maintenance or unforeseen power failures, eliminating blackouts.
Equipped with this device, two neighboring public transformers can now achieve real-time interconnection between their low-voltage AC areas, transforming their individual operations into a collaborative effort. In the event of a power outage due to maintenance or a fault in one transformer, the adjacent transformer seamlessly takes over, ensuring uninterrupted power supply. Furthermore, DC charging stations or other DC loads can be connected to the DC outlet of the flexible interconnection device, minimizing energy conversion losses and addressing future issues of load imbalance and excessive local loads in both transformer areas.
“The first low-voltage flexible interconnection device which debuted in Quzhou, can play a bigger role in the future,” one operations and maintenance engineer of the State Grid Zhejiang subsidiary said, adding that the company plans to deploy more such devices to enhance the DC acceptance capacity and fault resilience of the grids, thereby providing robust support for rural development initiatives.