Efficiency Enhancement and Cost Reduction through Speed Optimization of Two-regime Generator Set with Three-stage Synchronous Alternator

Variable-speed generators (VSG) offer numerous benefits over fixed-speed generators. These advantages include significant fuel savings, reduced noise emissions, and extended engine lifespan. However, VSGs have a major drawback: their high manufacturing cost owing to the expensive permanent-magnet generators (PMGs) commonly used in these generators, as well as the large size of the power electronics section, which has the same power rating as the generator itself. A solution to reduce the initial investment cost by introducing a two-regime generator (TRG) is proposed. The first mode operates at a constant speed for loads exceeding 50%, without the need for a converter. The second mode operates at variable speeds for loads below 50% using a converter that reduces its power by 50%, thus decreasing the investment cost. Additionally, the cost can be further reduced by replacing the PMG with a brushless synchronous generator. The controller employed in this study is a two-loop proportional-integral-derivative controller that exhibits favorable dynamics and compensates for dead times and parameter variations. TRG have shown a significant reduction in cost compared to VSG while retaining the advantages of the latter.