The corpus is led by a small group of established grid-equipment manufacturers and utilities that account for the bulk of filings, though the ranking table on this page shows the current order more precisely than any summary can. Several of these leading assignees show no filings in the most recent year tracked, which may reflect either a genuine slowdown or the roughly 18-month lag between filing and publication. Newer activity, including the most recent representative filing in this dataset, has come from university-affiliated research groups rather than the traditional incumbents. Anyone assessing competitive position should look at both cumulative family counts and recent-year momentum, since they tell different stories here.

Filing volume in this corpus rose to 20 records in 2018, its highest point, and had fallen to 8 by the 2022 midpoint with no clear recovery since. A likely driver is that the core converter-control architectures — voltage-source and modular multilevel converter control schemes in particular — were substantially claimed during the earlier filing wave, leaving less open claim space for follow-on filers. This does not mean R&D activity itself has slowed; it means the patent claim space around foundational control methods is more occupied than it was a decade ago. Readers should also account for publication lag when interpreting the most recent one to two years of the trend.

H02J, covering power supply and grid systems, appears in 228 of the 253 families in this dataset and is effectively the anchor classification for the field. H02M, power conversion including AC/DC conversion, appears in 119 records and frequently overlaps with H02J, showing that control claims are usually drafted around specific converter hardware rather than as abstract control algorithms. Smaller but relevant classes include H02H for protective circuitry, G05F and G05B for variable and regulating control systems, and H03K for pulse-based switching logic — each worth checking individually if a filing sits outside the core H02J/H02M pairing.

US20250246913A1, filed by King Fahd University of Petroleum and Minerals, describes an energy management system linking modular multilevel converters at each end of an HVDC line to separate AC grids, with one side integrating solar, wind and battery storage under a dedicated controller. As a 2025 filing it is too recent to have accumulated citation history, but its claim scope centres specifically on renewable-integrated dual-grid HVDC control rather than generic point-to-point transmission. Anyone designing an MMC-based control scheme that couples HVDC transmission with on-site renewable generation and storage should review its claims directly rather than assume the general HVDC control art has already covered that combination.

The classification data shows thin coverage relative to the H02J/H02M core in several adjacent areas: wind-farm-integrated power flow control, protective coordination for multi-terminal DC grids, pulse-based converter switching logic, and battery-storage-coupled converter control schemes. These are not unclaimed entirely, but their record counts are a fraction of the core classes, suggesting narrower claims there face a thinner prior-art background. Grid-forming HVDC control for weak or islanded grid interconnection is a similarly under-represented combination worth scoping before filing.