China's First Domestic Voltage-Source SFC for Pumped Storage Grid-Connected in Nanning
Reporters learned from China Southern Power Grid Energy Storage Co., Ltd. that on February 11, 2026, China’s very first homegrown voltage-source static frequency converter (SFC) for pumped storage hit a key milestone: it was successfully synced to the power grid on the first try at Unit 3 of the Nanning Pumped Storage Power Station.
All its core technical specs beat expectations. This success marks China’s full independent development of this new type of pumped storage frequency converter. It will go a long way to strengthen the security of the energy storage industry’s industrial and supply chains, and help build out a new type of power system.
Pumped storage units act as the 'regulator' of the new-type power system. When grid demand is low, they use surplus electricity to pump water uphill to the upper reservoir; when demand hits its peak, they release the water back downhill to generate power. This helps those intermittent, fluctuating renewable energy sources hook up to the grid steadily and reliably.
The static frequency converter (SFC) plays the critical role of an 'accelerator' during the pump start-up process. Its performance directly determines whether the unit can smoothly sync to the power grid.
When the unit operates in pumping mode, it depends on the static frequency converter (SFC) as a key control device. It delivers precise, adjustable voltage and frequency, gradually speeding up the roughly 500-ton electric motor from a standstill to its rated speed of over 400 revolutions per minute.
“In the past, China’s pumped storage SFCs were current-source types,” said Jin Yao, head of the R&D project at CSG Energy Storage. “They not only generated harmonics that undermined power system stability, but also had shortcomings such as reliance on imports and overly complex equipment structures.”
Beginning in 2024, CSG Energy Storage launched an independently controllable project: Key Technology Research and Engineering Application of New Static Frequency Converters for Large-scale Pumped Storage. This new SFC uses a fully domestic controller platform and power semiconductor devices. China now has full independent control over its core technologies, while its design has been simplified and optimized.
By adopting an innovative voltage-source technical route, together with advanced control strategies and power module designs, the converter has significantly reduced harmonics in the output current, lowering its negative impact on grid stability.
'The first static frequency converter (SFC) connected to Unit 3 of Nanning Pumped Storage Power Station has a total harmonic distortion (THD) of only 0.9%, far below the 3% design requirement,' introduced Yan Wenbin, a senior technical engineer at CSG Energy Storage Maintenance & Testing Company.
In line with China’s mid- and long-term development plan for pumped storage, the total number of key implementation projects and reserve projects exceeds 580, with a total installed capacity of over 720 million kilowatts. The new static frequency converter has broad prospects for large-scale industrial application.
'We will accelerate the pilot application of the new SFC in more pumped storage units, continuously improve equipment performance, and gradually expand its use to fields such as compressed energy storage, synchronous condensers and gas turbines. We will also promote the in-depth integration of scientific and technological innovation and industrial innovation on a wider scale,' Jin Yao stated.
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