Sub-Synchronous Resonance (SSR) Phenomena for Synchronous machine – Simulation & Analysis using EMTP and mitigation technique

Synchronous generators are exposed to oscillatory stresses due to their proximity to statcom devices and other power electronics devices, such as FSCs, HVDC controllers, and STATCOMs, which generate sub-harmonic frequencies. The interaction between sub-harmonic frequency components and mechanical mass can lead to Sub-Synchronous Resonance (SSR), an unstable and dangerous condition that causes torsional oscillation in the turbine generator shaft. This can reduce machine life, cause fatigue and damage to the shaft, and even result in its breakage. To avoid this, SSR detection/protection should be installed in generator units close to series compensated transmission lines. Different SSR modes can occur depending on the network condition and degree of compensation provided. Comprehensive Torsional Vibration Monitoring & Analysis systems are expensive, but there are cost-effective solutions to sense sub-harmonic quantities reliably at low amplitudes based on desired magnitude of sub-synchronous voltage and/or current. The offered solutions are supported by simulations, studies, modeling, and detailed analysis carried out in EMTP®.