Coming Soon-Grid-Forming Inverters to Stabilize India's High-VRE Power Grid

GRID-INDIA has released a discussion paper “Grid-Forming Technology and Possible Applications in the Indian Power System.” The report detailed all-India power system simulations (using PSSE and PSCAD models) and analysis of international deployments, contrasting emerging grid-forming (GFM) inverter controls with the dominant grid-following (GFL) paradigm. 

It quantifies GFM's potential to mitigate stability risks in weak-grid, inverter-heavy scenarios while proposing a phased roadmap involving BESS pilots, standards updates and targeted deployments. Stakeholder comments are solicited to inform policy and technical evolution.​ To understand the impact Grid-Forming inverters are having elsewhere, see this explainer on SaurEnergy.  

Explosive VRE Growth Amplifies Stability Risks

India's 500 GW non-fossil capacity target by 2030 - largely from 392 GW solar/wind - and net-zero by 2070 has propelled VRE installed capacity to 171,156 MW as of 31 July 2025, including 48,059 MW on the ISTS across 42 pooling stations. 

Capacity additions have compounded at 20 percent CAGR since 2015, with Rajasthan, Gujarat and southern states hosting massive RE complexes where 4-8 GW clusters are being integrated into single EHV nodes. 

Instantaneous VRE penetration has hit 40 percent all-India and more than 100 percent in states like Karnataka.​

From January 2022 to July 2025, the grid endured 68 VRE loss events exceeding 1 GW each, triggered by HVRT/LVRT shortfalls, scalar current logic flaws, RoCoF/anti-islanding mis-trips, conservative OV settings and PLL instability under weak grids. 

Corrective actions have halved event frequency and quantum, but rising inverter shares demand advanced controls to sustain inertia, damping and ride-through.​

GFL Limitations vs GFM Capabilities

Conventional GFL inverters, common in India, function as PLL-synchronised current sources injecting P/Q setpoints into a stiff grid - mature but vulnerable in low-SCR or high-IBR (>50 percent) environments, where PLL oscillations, poor fault support and delayed response cascade into trips. In other words, GFL inverters are focused primnarily on protecting themselves, shutting down immediately if they sense instability, ​inadvertently adding further to the same at times. GFM inverters on the other hand are supposed to collectively help stabilise such situations.   

GFM inverters shift to voltage-source mode, autonomously setting terminal voltage phasor (magnitude/angle) via droop, VSM (with swing-equation emulation) or oscillator controls, enabling PLL-free sync, virtual inertia/damping, harmonic regulation and black-start/islanding. Firmware-retrofittable on many platforms, GFM trades simplicity for weak-grid robustness, faster transients and system services mimicking - but outperforming in speed - synchronous machines.​

GFM Delivers Measurable Gains

As per the simulation results detailed in GRID-INDIA's discussion paper, grid-forming (GFM) inverters demonstrate clear superiority over grid-following (GFL) controls across a range of contingencies modeled on all-India and Rajasthan RE complex systems. In voltage stability scenarios, GFM units deliver shallower fault-induced dips, effectively damp post-fault oscillations, and suppress overshoots through rapid reactive power (Q) support, outperforming GFL's delayed and measurement dependent responses.

For frequency and rate-of-change-of-frequency (RoCoF) performance, GFM provides instantaneous inertia-like active power (P) adjustments, significantly curbing RoCoF. 

Recovery dynamics also favor GFM, with faster overall settling times that help avert cascading trips in large renewable energy (RE) clusters by enabling quicker restoration of active power and voltage stability.

Actionable Roadmap for India

The paper outlines an actionable roadmap tailored for India - prioritising equipping new BESS ≥50 MW in weak/remote sites with GFM for anchoring services. 

It advocates large-scale BESS-GFM pilots to validate models, protections and operations. Regulatory amendments to CEA/CERC/RLDC codes should add GFM specs (headroom, UNIFI/GC0137 tests) and compliance checks. Planning via SCR/contingency scans will optimize siting, supported by OEM transparency, better monitoring and operator training.

Authored by NLDC/RLDC teams under GRID-INDIA leadership, the paper invites feedback at [email protected] to refine this path for a resilient inverter-era grid.