ROCOF‐Constrained Solid‐State Transformer Frequency Predictive Control

ABSTRACT The increasing integration of power electronic‐based generation has significantly weakened power system frequency control due to reduced system inertia. In this context, the load contribution, through its frequency droop and inertia, plays a crucial role in stabilizing frequency fluctuations. However, the integration of solid‐state transformers (SST) prevents this contribution from occurring, because the DC‐link in the power converters decouples load dynamics from the main grid. Existing solutions attempt to mimic load contributions through synthetic demand responses; they often overlook both to meet grid code requirements and optimize control actions. This paper proposes a predictive frequency control algorithm to maximize load contribution via SSTs, constrained to grid code requirements. The proposal introduces two key innovations: from a transmission perspective, the control formulation is designed to minimize the rate of change of frequency (RoCoF) of the system frequency response; from a distribution feeder perspective, it incorporates constraints on voltage, frequency, and the RoCoF to ensure power quality and prevent the disconnection of distributed generation units (DG). Simulation results are obtained through a model of the involved dynamics, which are compared with a proportional controller. The proposed strategy achieves better performance indicators in all analysed scenarios.