A company in China has reproduced and suppressed wideband oscillations at a 500-megawatt (MW) solar-plus-storage power plant in what is described as the world’s first field test of the technology.
The test was conducted by Sungrow, a Hefei-based renewable energy company specializing in solar photovoltaics (PV) and energy storage systems. Intended to counter wideband oscillations, it took place at a plant in the Chinese province of Qinghai in September 2026.
Wideband oscillations are rapid electrical fluctuations that can, in fact, destabilize renewable power systems. Additionally, they can force generating equipment to disconnect from the grid or shut down entirely. This unpredictable nature has so far made them difficult to reproduce at operating plants.
Sungrow addressed this by deliberately triggering oscillations at a real-world plant. “For renewable energy to become a truly stable and reliable source of power, it is essential to develop autonomous fault self-healing and grid-support capabilities,” Pan Nian’an, chief engineer and chief expert at Sungrow, explained.
Testing grid stability
For the test, the engineers established weak-grid conditions at the 500-MW plant, which uses Sungrow photovoltaic (PV) inverters. The team identified three factors involved in triggering the oscillations: the plant’s power output, the system short-circuit ratio (SCR), as well as inverter control parameters.
They first adjusted these parameters, and then successfully reproduced a localized wideband oscillation in a controlled environment. They further tested how the PV inverters responded under different grid conditions.
Credit: Sungrow
Sungrow’s patented grid-strength adaptation technology identified the local grid strength within 40 milliseconds. The equipment then adjusted its control strategy to stabilize voltage and frequency.
The demonstration also tested Sungrow’s grid-forming control technology. The system is designed to help power electronics actively support grid stability rather than simply follow existing grid conditions.
According to the company, its grid-forming control strategy can maintain stable operation across an SCR range of 1 to 40, while also helping mitigate transient overvoltage.
Outside the lab
Wideband oscillations have previously been linked to major disruptions in power systems. For example, Germany’s BorWin1 offshore high-voltage direct current (HVDC) project experienced oscillations between 250 and 350 hertz in 2014. The incident damaged filter capacitors and contributed to a shutdown lasting around six months.
A 2019 incident at the UK’s Hornsea offshore wind farm located in the North Sea, off the coast of England, also involved subsynchronous oscillations. The event led to widespread disconnections. Around 3.2 percent of system load was lost, affecting roughly one million users.
Sungrow representatives believe that the latest test could help move oscillation-control technology beyond simulations and laboratories. It could eventually help renewable plants remain connected under extremely weak-grid conditions, cut lost generation, and increase the amount of electricity that facilities can export.
Nian’an said that the company plans to continue developing wideband oscillation suppression, grid-forming controls, and technologies for coordinating multiple energy sources.
“These efforts aim to support the stable grid integration and efficient utilization of renewable energy while strengthening the technical foundation for a secure and stable energy transition and next-generation power systems,” he concluded in a press release.