Transelectrica commissions STATCOM systems to stabilise voltage

Transelectrica has commissioned static synchronous compensator installations at its Sibiu Sud and Bradu substations under an investment programme valued at 51 million euros. The equipment provides dynamic voltage control, giving transmission system operators the tools required to manage volatile power flows driven by expanding renewable generation.

Rapid growth in inverter-based generation displaces conventional synchronous plant, removing intrinsic mechanical inertia and steady reactive power support from the transmission system. In response, modern grid operators deploy dynamic compensation plant capable of sub-cycle response to voltage excursions. The installations at Sibiu Sud and Bradu each deliver reactive power compensation rated at 150 MVAr in both capacitive and inductive modes. By injecting or absorbing up to 150 MVAr dynamically, the installations stabilise local bus voltages, suppress transient swings, and maintain transmission line thermal transfer capacity without demanding real power reserves.

For engineers running transmission substations, the presence of power electronics on this scale alters operational demands. Fast reactive support changes transient duty profiles across surrounding switchgear, instrument transformers, and large step-down power transformers. Rapid reactive swings mitigate overvoltage events, reducing dielectric stress across transformer winding insulation and surge arresters. However, the introduction of high-speed solid-state switching also requires vigilant harmonic monitoring to verify that resonant conditions do not accelerate thermal degradation in nearby oil-immersed transformers.

What this means for asset owners in the Balkans and the Black Sea region: Transmission utilities and generation developers in Romania face increasingly volatile voltage profiles as renewable integration accelerates. Substation operators must re-evaluate harmonic filtering and insulation coordination under dynamic reactive compensation schemes. Plant teams should align power transformer diagnostic intervals with IEC 60076 principles, ensuring that increased high-speed reactive cycling and harmonic loading do not degrade bushings or accelerate dissolved gas formation in transformer insulating fluids.