A Grid-Forming Control Method for PEMFC Power Conversion Systems with Power Ramp Rate Limitation to Prevent Fuel Starvation

Polymer electrolyte membrane fuel cell (PEMFC) stacks, compared to other renewable sources, are promising candidates for grid-forming (GFM) capability due to their sufficient power reserves. However, operational constraints related to fuel supply conditions aimed at maintaining high stack efficiency can cause fuel starvation under rapid power variation. This issue introduces ramp rate limitations analogous to those observed in synchronous generators (SGs). To overcome this constraint, this paper proposes an advanced GFM control strategy for PEMFC power conversion systems, explicitly considering power ramp rate limitations to prevent fuel starvation. In the proposed algorithm, a two-stage converter fully replicates the actual behavior of the SG in a stage-wise manner, while an enhanced current-limiting scheme precisely saturates overcurrent and improves dynamic performance during fault transient. The DC/DC converter functions as a prime mover to regulate damping power from the stack, thus it effectively eliminates limited GFM problems. In addition, the DC/AC inverter emulates the electromechanical response of the SG to compensate for power imbalance caused by the stack's power ramp rate; the DC-link capacitor effectively serves as an energy buffer to prevent fuel starvation. The practical feasibility of the proposed GFM algorithm for the PEMFC system is experimentally evaluated using hardware-in-the-loop testing.