Two-Stage Robust Voltage Control Strategy for Seaport Microgrids With Health-Aware All-Electric Ships

The uncertain and uncoordinated charging power of berthed-in all-electric ships (AESs) will introduce new challenges to voltage security in seaport microgrids. This article develops a two-stage robust and health-aware voltage control strategy to mitigate voltage violations while guaranteeing the benefits of AES. In the first stage, a robust optimization model is formulated to minimize power losses (PLs) under the worst case through the dispatch of on-load tap changers (OLTCs) ahead of the day. Except for photovoltaic (PV) output and load demand, the uncertainty set of AES is also formulated considering their arrival times and state of charge (SOC) of batteries. The optimization problem is formulated as a mixed-integer second-order cone program (MISOCP) and solved with the column-and-constraint generation (C&CG) algorithm to achieve effective solutions. In the second stage, PVs and AES are coordinated with shorter snapshots to regulate voltages in both normal voltage control mode (NVM) and emergency voltage control mode (EVM). A novel 3-D charging power criterion is proposed, which emerges the battery degradation cost, SOC, and berthing time (SOCBT) of AES. The charging criterion is then implemented in a power sharing algorithm, which can reduce total aging rates and guarantee the full charging of AES at the departure time. Our method is tested on the European Union (EU) 16-bus microgrid embedded with a seaport, and simulation results demonstrate its advantages in mitigating voltage violations and ensuring the benefits of AES. 

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