Customized Coordinated Voltage Regulation and Voyage Scheduling for All-Electric Ships in Seaport Microgrids
Xianzhuo Sun, Jing Qiu, Yuechuan Tao, Huichuan Liu, Junhua Zhao
Abstract
This paper proposes a customized coordinated voltage regulation and voyage scheduling strategy for all-electric ships (AES) to find a trade-off between minimizing operation cost during cruising and reducing power losses of microgrids, which also guarantees system voltage security. Based on a predefined sea route with minimum added resistance, the optimal voyage scheduling is first performed to achieve energy management and speed adjustment of AES. This process also obtains multiple AES arrival time-state of charge ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T<sub>a</sub></i> - <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SOC<sub>a</sub></i> ) pairs and sends them to the microgrid central controller (MGCC). The MGCC then performs optimal voltage regulation to minimize power losses through the dispatch of on-load tap changers (OLTC), photovoltaic inverters (PVs) and berthed-in AES. The voltage regulation model is an extension of the conventional volt/var optimization by incorporating berth allocation problems and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T<sub>a</sub></i> - <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SOC<sub>a</sub></i> constraints. To achieve effective solutions, both the voyage scheduling and voltage regulation problems are converted to mixed-integer linear programs (MILP) with linearization methods. Moreover, a customized coordinated optimization procedure embedded with a satisfactory index (SI) is proposed to solve the problem, which helps select <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T<sub>a</sub></i> - <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SOC<sub>a</sub></i> pairs for each AES and ensures an acceptable operation cost during the voyage scheduling. The simulation results verify that the proposed method achieves secure and optimal operation in seaport microgrids. It can also find a trade-off between minimizing the operation cost of AES and reducing power losses in microgrids.