Global inverter and energy storage supplier Sungrow has achieved a industry milestone by controllably reproducing and successfully suppressing wideband oscillation at an operational 500 MW solar-plus-storage plant in Qinghai, China.
The field test addresses one of the most critical operational challenges facing power grids as renewable energy penetration accelerates globally. Wideband oscillation—caused by complex interactions between power electronics and grid impedance—has historically led to severe infrastructure damage and wide-scale outages.
Previous global incidents highlight the severity of the phenomenon. In 2014, Germany’s BorWin1 offshore HVDC project suffered a six-month shutdown following 250–350 Hz oscillations that destroyed converter filter capacitors. Similarly, in 2019, subsynchronous oscillations at the UK’s Hornsea offshore wind farm triggered widespread disconnections, impacting nearly one million consumers and shedding 3.2% of the system load.
Despite theoretical research, field validation has been constrained by the risks associated with intentionally inducing power grid instability. To bridge the gap between simulation and real-world application, Sungrow and its industry partners conducted controlled testing across the 500 MW Qinghai facility using on-site Sungrow PV inverters.
The engineering team established weak-grid conditions by isolating three critical variables: power output, system short-circuit ratio (SCR), and control parameters. Once localized system oscillation was safely triggered, the team evaluated the dynamic response of the inverters under varying grid states.
During testing, Sungrow’s patented grid-strength adaptation technology detected changing grid conditions within 40 milliseconds, automatically recalibrating control algorithms to stabilize system voltage and frequency. The test also verified the performance of grid-forming control strategies, demonstrating stable operation across an SCR range of 1 to 40 while mitigating transient overvoltage risks.
The successful field trial transitions wideband oscillation mitigation from theoretical modeling into validated engineering practice. The technology is expected to enhance plant stability under weak grid conditions, unlock higher power export limits, and reduce generation curtailment for utility-scale assets.
“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,” said Pan Nian’an, Chief Engineer and Chief Expert for Utility PV BU at Sungrow. Pan added that the company will focus future R&D efforts on grid-forming control, wideband oscillation suppression, and multi-energy coordination to bolster next-generation power grid security.
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