Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Optimization of PV-hybrid power system considering environmental uncertainties
Jianyun Zhu, Li Chen*

State Key Laboratory of Ocean Engineering, Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai Jiao Tong
University, Shanghai, China

ABSTRACT2018; Yuan, Zhang, Shen, Yan and Long, 2018). In optimization-based
methods, sizing problems are shifted into mathematical optimization
problems and solved by different kinds of algorithms. For instance, amethod for the optimal sizing of PV-HPS is proposed for minimum
investment cost, fuel cost and GHG emission (Lan, Wen, Hong, Yu andZhang, 2015). Fraction of the deck being used for solar power capture
is optimized for GHG emission reduction (Mphatso, Huy, Alessandro
and Aykut, 2021).
Uncertainties in environment parameters can considerably affect theperformance of PV-HPS and may lead to misleading optimization
results. For example, besides PV’s own characteristic, the output of aPV module depends on solar irradiance and ambient temperature.
Deterministic optimization methods based on one typicalenvironmental condition inevitably lead to inaccurate assessment of PV
performance. To fill this gap, an optimal sizing method was proposedwith the help of Monte Carlo method (Zhu and Chen, 2020). One
thousand scenarios were generated by Latin Hypercube sampling forperformance evaluation of each design. Results show that the optimized
PV-HPS provides benefits on average fuel consumption and GHG
emission compared with the traditional propulsion system. However,serving a problem with such high number of scenarios can becomputational cumbersome. In addition, the method did not take zenith
angle into account that can bring about major error in the calculation of
PV output. What's more, although still water is universally consideredin PV-HPS sizing reports, ships sail under different sea conditions inreality. Neglecting the effect of wave can lead to incorrect thrust
requirement of PV-HPS, resulting in sub-optimal designs.
Given above, a stochastic optimal sizing approach of PV-HEPS isproposed in this study pursuing minimum GHG emission and lifecycle
cost. The model of the PV-HEPS system with scalable components isestablished. Uncertainties in solar irradiance, zenith angle, ambient
temperature, wave height, wave period and wave direction areconsidered. Two joint distributions are established based on copulafunction to express the interconnect between uncertainties that affectPV output and ship resistance, respectively. A bi-bin method isintroduced for scenario reduction. The design space exploration isperformed with Non-dominated Sorting Genetic Algorithm II (NSGAII). The effectiveness of the proposed method is demonstrated using acase study of an unmanned ship.

In this paper, photovoltaic technology is introduced into hybrid powersystem as PV-hybrid power system (PV-HPS) to take advantage ofabundant solar energy. For the sake of enhancing environmental andeconomic benefits, a stochastic optimal sizing method is proposed
perusing minimum greenhouse gas (GHG) emission and lifecycle cost.
Considering the uncertain nature of solar energy as well as wave
condition, the stochastic behavior of solar irradiance, zenith angle,
ambient temperature, wave height, wave period and wave direction aremodeled. Two joint distributions are established based on copulafunction to express the interconnect between uncertainties that affectPV output and ship resistance, respectively. A bi-bin method isintroduced for scenario reduction to improve computational efficiency.
Case study suggest that the proposed method outperforms thedeterministic method under more realistic scenarios.

KEY WORDS: stochastic optimization; PV-hybrid power system;
environmental uncertainty; greenhouse gas emission; lifecycle cost.

INTRODUCTION
Carbon neutrality strategy has been proposed by many governments
due to increasing energy and environmental concerns. Recent trends
show that hybrid power system (HPS), as a kind of green technology, isgaining universal attention in the field of shipping industry (Sciberras,Zahawi, Atkinson, 2017). For further greenhouse gas (GHG) emission
reduction, solar power technology has been introduced into HPS as PVhybrid power system (PV-HPS) to take advantage of solar energy(Chybyung, Byongug, Peilin, Hayoung, Seongwan, Hyeonmin, Dong andAhmad, 2022.).
Reasonable design is the foundation for PV-HPS to achieve low GHG
emission and life cycle cost. The sizing methods can be mainly divided
into two kinds, i.e. meta-heuristic methods and optimization-based
methods. In meta-heuristic methods, size parameters are determinedbased on experience or guidelines. For example, a passenger ship wasequipped with a 3.2 kW PV array to decrease the dependence on fossil
fuel (Lee, Shin, Yoo, Choi and Kim, 2013). Yuan et al. performed
sophisticated studies on the design and control of a PV-HPS for a 5000vehicle space car and truck carrier (Yuan, Wang, Yan, Li and Long,SYSTEM MODELLING3891