LS Power Commissions 800 MVAR STATCOM for PG&E Grid Stability
- News Power Quality Voltage & Reactive Power
Marin Holt
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- LS Power's Orchard Substation energized March 12, 2025 with 800 MVAR of dynamic reactive power — the largest STATCOM installation in North America
- Two u00b1424 MVAR STATCOM blocks connect directly to PG&E's Gates 500 kV substation in Fresno County, San Joaquin Valley
- CAISO selected LS Power in 2020 from ten qualified proposals under FERC Order No. 1000 competitive transmission planning
- Project completed below CAISO's original cost estimate; 100,000+ construction hours with zero OSHA recordables
- Siemens Energy supplied all four STATCOM systems across two California substation projects totaling 848 MVAR combined
- Diablo Canyon nuclear plant (2,200 MW) retired in 2025, removing baseload reactive power support that STATCOM now replaces
LS Power Grid California energized the Orchard Substation on March 12, 2025, bringing online 800 megavolt-amperes reactive (MVAR) of dynamic reactive power capacity, the largest static synchronous compensator (STATCOM) installation in North America. Located in Fresno County, the project connects two 424 MVAR STATCOM blocks to PG&E‘s Gates 500 kV substation in the San Joaquin Valley, addressing voltage stability risks that CAISO identified following the scheduled retirement of the Diablo Canyon nuclear power plant.
What Is Happening
CAISO selected LS Power Grid California in 2020 as project sponsor for the Gates 500 kV Dynamic Reactive Support Project through a competitive process under FERC Order No. 1000, choosing LS Power from ten qualified proposals. Construction began in 2023 and was completed within two years, with the substation reaching full operational status on March 12, 2025, under CAISO’s original cost estimate. Siemens Energy supplied the four STATCOM systems across two California substation projects: two units at the Orchard Substation (Gates 500 kV interconnection) and two units at the new Fern Road Substation connecting Round Mountain to Table Mountain 500 kV transmission lines.
The Orchard Substation is LS Power Grid California’s first transmission asset in California, with five additional transmission infrastructure projects in development across the state. Construction was performed by TTR Substations using IBEW Local Union 1245 members, completing over 100,000 work hours with zero OSHA recordable incidents.
Critical Perspective
The Orchard Substation adds 800 MVAR of reactive power capacity. This STATCOM installation is larger than the 600 MVAR STATCOM at Duke Energy’s Clover facility. The project was completed in two years, under budget, unlike the 2013 completion of the 345 kV transmission line in Texas which ran 30% over its initial cost estimate. Given the increasing integration of inverter-based resources, what is the projected lifespan of this STATCOM’s reactive power support against evolving grid dynamics?
Why It Matters
Diablo Canyon provided approximately 2,200 MW of baseload power in California’s Central Valley alongside substantial reactive power capability. Both real power output and reactive power support disappear when a nuclear plant retires. STATCOMs compensate for the lost reactive power by injecting or absorbing reactive current in milliseconds, maintaining voltage within acceptable limits during transmission contingencies and system events. Without the Orchard installation, CAISO identified that high voltages and thermal overloads during extreme contingencies would threaten reliability in the San Joaquin Valley as renewable generation continues to grow.
California has committed to 55 percent renewable electricity sourcing by 2031. Unlike synchronous generators, solar and wind inverters do not inherently provide reactive power support, making grid-connected reactive compensation infrastructure increasingly critical as the generation mix shifts. The Gates project demonstrates that CAISO’s competitive transmission planning process can deliver large-scale voltage support infrastructure before the retirements that create the need.
Technical Details
A STATCOM uses voltage-source converter technology to produce or absorb reactive power continuously, responding to voltage deviations within one to two electrical cycles, far faster than mechanically switched capacitor banks or synchronous condensers. The Orchard Substation’s two 424 MVAR blocks connect directly to the Gates 500 kV bus, providing bidirectional reactive power that stabilizes voltage under both light-load and heavy-load contingencies. The Fern Road Substation’s parallel installation provides voltage control and support during transmission outages along the Round Mountain to Table Mountain 500 kV corridor in Northern California.
The VSC topology generates high-frequency harmonic sidebands at multiples of the PWM switching frequency, typically 1,350 Hz, corresponding to 22nd and 23rd harmonic orders at 60 Hz. The CAISO-identified post-Diablo Canyon voltage stability gap created N-1 contingency scenarios where the 500 kV network could not maintain ANSI C84.1-2020 Range A limits without dynamic reactive support of this scale.
