Coordinated Control of a Hybrid-Electric-Ferry Shipboard Microgrid

Abstract

DC and DC/AC hybrid distribution and energy storage for shipboard power systems (SPS) are becoming a major trend due to efficiency improvement, space saving, and maneuverability enhancement. This paper has taken a real hybrid-electric-ferry as a case-study to integrate battery units (BUs) to a DC bus for supplying the propulsion motors. Further, two diesel generators (DGs) are connected to the AC bus to supply the hotel loads and a bidirectional DC/AC converter with an LCL filter is responsible for the power flow between AC and DC buses. This power topology is flexible for this ferry operation in pure electric, range extended and shore power modes. DC bus voltage is stabilized and its voltage ripple is limited by BUs' interleaved three-phase bidirectional DC/DC converter with its controller considering the operation states of propulsion motors. A coordinated power flow control between DGs and BUs is presented that the system frequency is fixed for the optimal operational efficiency of the diesel engines and a Q-V droop control plus a virtual impedance loop is used to make different AC bus voltage. Synchronization with shore power and DC/AC converter is facilitated by P-f droop control. Simulation results are presented to validate the proposed control approach in different missions.

A Review of the Conceptualization and Operational Management of Seaport Microgrids on the Shore and Seaside

“…Thus, harnessing energy from RES is more economical due to the local generation advantages. However, ports have a limited space for RES installation [96]. Undeniably, solar panels can be installed on the flat rooftop of the buildings or warehouse but with restricted capacity and it is not applicable for large-scale exploitation.…”

“…It is well known that ships have very limited space due to existing bulky equipment on board, especially cargo ships, which usually use the space to place the cargo. Furthermore, coordination of the RES will be complicated because ships are always on the move and isolated when they are at sea [96].…”

Dynamic Performance Assessment of NG-MVDC Shipboard Power System with Distributed Electric Propulsions

“…M a n u s c r i p t attractive due to unprecedented advantages such as weight and volume reduction, synchronization problem elimination, power density improvement and reliability enhancement [2,3,5]. According to the above mentioned, Next-Generation Medium Voltage Direct Current (MVDC) SPS is a really complex system which provides a lot of benefits.…”

Dynamic Modeling, Stability Analysis, and Power Management of Shipboard DC Hybrid Power Systems

“…In this case, to reach the enhanced unequal load sharing, it is recommended to have a mid-level controller (e.g. PI controller) that adjusts voltage references to regulate the output powers from each power source [13], [14]. Then, AFEs and DC-DC converters should follow the dynamic references affecting the system stability and power quality.…”

“…Voltage stability is also studied against the negative effect of constant power loads (CPL) in [17]- [19]. Influence of controller parameters is also studied in the literature such as the effect of frequency and voltage droop gains on the AC power system stability [20], estimation of the stable voltage operation range for permanent magnet generator and diode rectifier [6], coordinated control of a hybrid-electric SPS [14], [21], three-layer control design of DC SPS [13] and study of a predictive control approach to regulating the DC voltage in hybrid-electric SPS [22].…”