Analysis and Control of Acoustic Emissions from Marine Energy Converters

Abstract Environmental licensing related to underwater acoustic emissions represents a critical bottleneck for the commercial deployment of marine renewable energy. This study presents a control engineering framework to mitigate acoustic risks from tidal current converters (TCCs) without compromising project viability. A MATLAB/Simulink model of a TCC was utilized to evaluate two distinct mitigation tiers: (i) architectural modification, comparing a geared induction generator against a direct-drive permanent magnet synchronous generator (PMSG) and (ii) operational control, analysing the impact of switching frequencies and maximum power point tracking coefficient (Kopt) tuning. Results indicate that lowering switching frequencies (Fs) is ineffective, increasing power electronic losses by over 2000% with negligible acoustic benefit. Conversely, the direct-drive PMSG architecture reduced sound pressure levels by approximately 10 dB re 1 μPa, effectively eliminating mechanical tonal noise. For existing geared systems, de-tuning the Kopt coefficient by a factor of 1.2 reduced the probability of exceeding temporary threshold shift limits for marine mammals, with a quantified energy yield reduction of 3.58%. These findings propose a hierarchical mitigation strategy: selecting direct-drive topologies for acoustically sensitive sites, and utilizing maximum power point tracking coefficient based power curtailment as a transient operational mode during critical biological migration periods.