Pelagic Islands Research Articles

A dual-standby power source configuration scheme for micro grid in Pelagic Island

Realizing clean energy supply is important for the sustainable development of pelagic island. The volatility and randomness features of renewable energy generation may reduce power supply reliability, thus backup units is necessary in micro-grid in pelagic island. This paper proposed a dual-standby configuration scheme based on Sequence Operation Theory to achieve reliable power standby. Firstly, characteristics of standby units, micro gas turbine and diesel generator, are analyzed. Next, the probability distribution function models of wind, photovoltaic and load demand in pelagic island are established, and the reliability index of power shortage probability is calculated by Sequence Operation Theory. Then, the two-stage dual-standby control scheme to make full use of the complementary standby units is introduced and object function to minimize equivalent annual cost on the premise of satisfying probabilistic reliability index is modeled. Hybrid integer particle swarm algorithm is used to solve the problem. Finally, the proposed model for dual-standby configuration is applied to a pelagic island. The simulation results show that the proposed method can meet the load demand in both daily and extreme weather and achieve superior economy.

A production and transport scheduling strategy of energy and resources of pelagic clustering islands based on generalized movable energy storage

At present, most pelagic islands rely on the mainland for resource replenishment. And due to the limited island area, it is not sufficient to simultaneously place enough basic load facilities and new energy generation and consumption facilities on a single island. Considering pelagic islands are distributed in groups, vigorously developing renewable energy around islands can be considered, and the islands can be divided into resource islands and load center island. Resource islands can use renewable energy to produce and transport electric power, fresh water and hydrogen which are needed for load center island. The whole islands group forms a cleaner and green integrated energy system. However, this kind of system will face the coexistence challenge of intra-island independent optimization and inter-island collaborative optimization, continuity of energy production and discreteness of transportation, production scheduling and route planning, which is less studied. To ensure reasonable operation of the energy system, according to multi-agent theory, the inter-island energy and resource production and transportation scheduling model based on generalized movable energy storage can be divided into two parts: load center island agent scheduling model and resource islands agent scheduling model. And scheduling objectives and constraints of each agent in two scenarios are determined. The simulation results show that the new model can comprehensively take into account the production efficiency of equipment, production effectiveness and transportation cost and realize the rational production scheduling and transportation of energy and resources under the premise of meeting the demand of load center island.

Distributed secondary optimal control for self‐maintaining microgrids on pelagic islands

AbstractConsidering the geographic distance, self‐maintaining microgrids are widely built to supply power on pelagic islands, where developing distributed autonomous control strategies while guaranteeing microgrids’ resilience and energy security have gained increasing attention. However, most existing distributed control strategies restore frequencies in an asymptotic manner, which may not meet the requirement for safe and rapid recovery after disasters. Meanwhile, self‐maintaining microgrids have relatively low percentages of fossil fuels. Power sharing among distributed energy sources (DERs) under most existing control relies on the droop coefficients, which may lead to inefficient operations. To overcome these challenges, this paper proposed a distributed control strategy for self‐maintaining microgrids. The frequency restoration time can be explicitly optimized and is robust to changes of system states, which provides faster recovery performance under disasters. The steady‐state powers of different DERs are regulated for different kinds of DERs separately and are independent of the droop coefficients, where the proper use of renewable energy under energy security can be achieved. The proposed control enhances the resilience of microgrids against disasters and meets the requirement of energy security on islands. The algorithms in the paper are verified by both simulation and experiment studies under various conditions.

Multi-scenario planning of pelagic island microgrid with generalized energy storage under the influence of typhoon

Stand-alone microgrid system consist of hybrid wind/photovoltaic/energy storage is one of the effective approaches to solve the problem for future pelagic island power supply. Also, the frequent typhoons have brought serious impact to the pelagic island microgrids. In this context, a multi-scenario planning model for pelagic island microgrid with generalized energy storage (GES) is proposed to address the issues of high-impact, low-probability typhoon events and insufficient flexibility in low-impact, high-probability situations. Given the impact of typhoons, the planning scenarios of island microgrids are divided into regular, typhoon and typhoon early warning scenarios. Meanwhile, the selection method for each type of scenario is given. In addition, this paper establishes the unified GES model which includes power to gas-gas storage-micro gas turbine (P2G-GS-MT), transferable loads, reducible loads, and electric energy storage. The proposed methodology has been validated on an enhanced microgrid, resulting in a cost reduction of 11.9% compared to traditional method. The results demonstrate that this approach reduces the planning capacity of equipment, cost reduction, and ensure uninterrupted power supply to important loads even during typhoon conditions.

Self-Sustaining of Post-Disaster Pelagic Island Energy Systems With Mobile Multi-Energy Storages

Extreme natural hazards may damage the pelagic island energy system (PIES) integrating distribution systems, cold storages and desalination stations, resulting in the electric service interruption, stored food deterioration, and freshwater shortage. To alleviate the energy demand of residents as much as possible before the arrival of mainland emergency resources, a novel self-sustaining strategy of post-disaster PIESs with mobile multi-energy storages is proposed in this paper. First, mobile multi-energy storages are used to delivery electricity, ice, and water among stations to increase the resource supply resilience. Their differences in resource delivery time and transportation energy consumption are modelled. On this basis, mobile multi-energy storages are coordinated with diesel generators, cold storages, desalination devices, network reconfiguration, and islanded grid merging for self-sustaining of post-disaster PIESs. The utility loss evaluation model of the common electric load shedding, food deterioration, and freshwater shortage is established, in order to better reflect and respond to the needs of residents. Robust optimization methods are also used to address the uncertainties of the renewable generation, multi-type load demand, and especially energy transmission (i.e. traffic congestion time and line repair time), making the restoration strategy reliable. Finally, case studies verified the superiority of the proposed strategy.

Renewable Energy Maximization for Pelagic Islands Network of Microgrids Through Battery Swapping Using Deep Reinforcement Learning

Renewable Energy Maximization for Pelagic Islands Network of Microgrids Through Battery Swapping Using Deep Reinforcement Learning

The power optimization on tie-line for the island energy internet based on interactive distribution network

In order to better study the characteristics of energy internet of pelagic island, this paper summarizes the latest research progress of energy internet, divides the research of energy internet into mainland energy internet and island energy internet, and consider that island energy internet should include two core networks of electric energy and thermal energy. Based on the study of the structure and control strategy of core hardware equipment including energy router, energy switch and energy interface, a three-section structure of island energy internet based on these three core hardware devices is proposed to optimize the current research structure of energy internet. With the geographical location, the optimization on generation of wind power, solar power and other renewable energy on resource island is applied with multiple objective particle swarm optimization (MOPSO). The capacity on various sources including battery and fresh water of energy exchange vessel optimized. Finally, the case study about pelagic islands indicated the feasibility of pelagic island energy internet. Finally, the structure of an island energy internet is built.

Analysis on Structure of Interacted and Interconnected Micro Grid Based Energy Internet on Pelagic Clustering Islands

Compared with the direct access to the main power grid and diesel generators, this paper puts forward the scheme of using electric ships to shuttle between islands to transport electric energy, analyzes the limitations and defects of its application in offshore islands; and then puts forward a comprehensive energy supply system of offshore islands. The comprehensive energy supply system can make full use of the rich renewable energy of the islands, and realize the optimal allocation of the overall resources of the islands. At the same time, the energy supply system can break the isolated development pattern of island power grid and connect the island group power exchange ship. This paper analyzes the connotation and characteristics of the system, puts forward the key technology for building the integrated energy supply system of ocean island group, and gives the design and operation analysis example of power exchange ship.

The Power Planning of Interacted and Interconnected Microgrid in Pelagic Clustering Islands Based on Energy Storage Vessel Transport Route

Sang, Z.-x.; Fang, R.-c.; Du, Z.; Yang, D.-j.; Yan, J., and Lei, H., 2020. The power planning of interacted and interconnected microgrid in pelagic clustering islands based on energy storage vessel transport route. In: Liu, X. and Zhao, L. (eds.), Today's Modern Coastal Society: Technical and Sociological Aspects of Coastal Research. Journal of Coastal Research, Special Issue No. 111, pp. 172–177. Coconut Creek (Florida), ISSN 0749-0208.There is a lack of effective liaison among pelagic islands; however, an interconnection mode by submarine cables is not feasible or economical. In this paper, we propose to replace some of submarine cables with energy storage vessel (ESV) routes and establish a hybrid power transmission network based integrated energy system of pelagic clustering islands. First, an ESV route was modeled to analyze the transmission efficiency and cost. Then, a hybrid power transmission network planning model of the island integrated energy system was proposed based on multiscene generation and scene clustering. The objective function was the minimum overall cost considering the additional power supply cost under extreme weather scenario. The model was optimized by chaotic gravitational search algorithm. The feasibility and effectiveness of the proposed method are verified through simulation results.

Scheduling of energy management based on battery logistics in pelagic islanded microgrid clusters

According to resource distribution, the pelagic islands can be divided into the load center island and resource-rich islands. Since the islanded microgrids are geographically isolated, an economical and feasible way of energy flow among islanded microgrids is urgently needed. This paper proposes a novel energy management system (EMS) based on battery logistics by electric vessel to optimize the operation of pelagic islanded microgrid clusters (PIMGC). Firstly, the battery logistics among islanded microgrids and energy flow within islanded microgrids are modeled. Furthermore, an information gap decision theory-based EMS model is established with the uncertainties of renewable energy generators. Then, the Generalized Benders method is presented to decompose the scheduling problem into a master problem of discrete battery logistics optimization and subproblems of power flow feasibility checking. Finally, case studies with the proposed EMS are conducted with three islands in the South China Sea. The simulation results show that the proposed EMS is feasible and economical to supply energy for PIMGCs, providing a reference for the energy supply system of pelagic islands.

The Integrated Energy System with Multiple Resources Integration in Future Distribution Network of Pelagic Clustering Islands

Sang, Z.; Huang, J.; He, J.; Fang, R.; Yan, J., and Lei, H., 2020. The integrated energy system with multiple resources integration in future distribution network of pelagic clustering islands. In: Yang, D.F. and Wang, H. (eds.), Recent Advances in Marine Geology and Environmental Oceanography. Journal of Coastal Research, Special Issue No. 108, pp. 42–47. Coconut Creek (Florida), ISSN 0749-0208.In the overall strategy of national security, the pelagic clustering islands have a special geostrategic significance as an important fulcrum and platform to safeguard national coastal defense and maritime rights and interests. Reliable energy supply is the artery of the development and construction of the pelagic clustering islands. Still, the current research is mostly aimed at the offshore islands, lacking relevant theories and methods for the pelagic clustering islands. Therefore, the current situation of the island grid research, with its limitations and defects when applied to the pelagic clustering islands, are inquired and analyzed in the paper firstly. Furthermore, an integrated energy system (IES) as a future distribution network of pelagic islands is proposed for the purpose of taking full advantage of the abundant renewable energy to optimize the configuration of multiple resources of the islands as a whole. The IES breaks the isolated development pattern of island grid, taking the islands as a whole, interconnected through the originality energy storage vessels (ESVs). Finally, the key technologies required to construct the IES of pelagic islands are summarized, and the design of ESVs as well as the case study are given in order to provide a reference for the development and construction of pelagic clustering islands in China.

Energy Transmission Mode Based on All-electric Vessels for Pelagic Islands and Its Coordinated Scheduling Strategy

There is a lack of effective liaison between pelagic island microgrids, leading to inflexible transmission of energy between islands. However, the interconnection mode by submarine cables is not economical due to the long distances between islands. Therefore, an energy supply mode based on allelectric vessels is proposed in this paper. The framework and working principle of the mode are first introduced. A two-stage optimization model is established considering the coordinated operation of island microgrid and the swapping plan of all-electric vessels. The simulation results show that the proposed transmission mode can reduce overall costs and the proposed scheduling strategy can promote renewable energy consumption and reduce operation costs.

The design and dispatch strategy of renewable energy absorption facility on pelagic island

The peaceful development and utilization of pelagic island occupy vitally important position in the maritime development. For the rich resource islands that support the load center island by shipping, the efficient operation of off-shore renewable energy absorption facility (REAF) is of vital importance. Focusing on this issue, the hydrogen electrolyzer containing multiple energies (battery, hydrogen and cool) is designed in this paper. This design promotes the energy absorption efficiency of REAF significantly. On the other hand, the flexible-size decision tree pruning (FSP) and improved reinforced learning Monte-Carlo method (IRLMCM) are proposed in this paper, and the hierarchical dispatch strategy of REAF based on the above algorithms is designed. Case studies show that the dispatch strategies of REAF proposed in this paper can improve the energy absorption ability significantly. At last, the possible improvement methods of the dispatch strategies of REAF are discussed in this paper.

Multi-energy management with hierarchical distributed multi-scale strategy for pelagic islanded microgrid clusters

The pelagic islands usually include resource islands and load islands with electricity and natural gas transactions among them. Since they are apart from the main land, the finiteness of energy resources results in crucial need of developing efficient energy management framework for the pelagic islanded microgrid clusters (PIMGCs). In this paper, we introduce a novel multi-energy management framework for a PIMGC, where the operators on resource islands sell energy resources, while the aggregators and users on load islands dispatch and consume energy resources, respectively. The multi-scale energy management strategy is proposed, where the operators determine their daily optimal energy supply in a distributed collaborative way by adopting the primal-dual subgradient method, each aggregator determines its daily optimal energy demand and hourly optimal energy usage, and each user determines its hourly optimal energy consumption. A hierarchical day-ahead distributed algorithm is proposed to obtain the Nash equilibrium strategy, where the operators minimize their aggregate operational cost, each aggregator maximizes its revenue and each user maximizes its payoff. Simulation results are provided to show the effectiveness and benefits of the proposed multi-energy management framework for the PIMGCs.

The late-Holocene avifaunal assemblage from the island of Palagruža (Croatia): The earliest record of the Northern Gannet in the Adriatic Sea

The late-Holocene bird remains retrieved during archaeological excavations on pelagic island of Palagruža, Croatia, were analysed. The results of the analysis revealed presence of representatives of nine families: Procellariidae, Sulidae, Ardeidae, Accipitridae, Phasianidae, Rallidae, Laridae, Strigidae and Corvidae. Among the bird remains, the most numerous were remains of the Northern Gannet, Morus bassanus, which were widely distributed in the Mediterranean during the late Pleistocene. The finding of the Northern Gannet bones on Palagruža represents the first fossil record of this species in the Adriatic Sea and indicates a possible breeding site on the island. The direct Accelerator Mass Spectrometry (AMS) radiocarbon dating on two gannet bones revealed the age of 2878 ± 34 and 2694 ± 45 yr BP. Gannet bones from Palagruža were some 6000 years younger than other fossil records of that species from the Mediterranean. It is possible that during the gannet’s northward distributional shift, probably caused by centennial climatic variability and human pressure, gannet colony on that remote island in the Adriatic lasted longer than in the rest of the Mediterranean and existed until the late-Holocene. Lower sea-surface temperatures compared with the eastern Mediterranean, higher nutritive productivity and remoteness of Palagruža provided adequate breeding opportunities during that period.

The 'CORSAGE' programme: Continuous orbital remote sensing of archipelagic geochemical effects

Current and pending oceanographic remote sensing technology allows the conceptualization of a programme designed to investigate ocean-island interactions that could induce short-term nearshore fluxes of particulate organic carbon and biogenic calcium carbonate from pelagic island archipelagoes. These events will influence the geochemistry of adjacent waters, particularly the marine carbon system. Justification and design are provided for a study that would combine oceanographic satellite remote sensing (visible and infrared radiometry, altimetry and scatterometry) with shore-based facilities. A programme incorporating the methodology outlined here would seek to identify the mechanisms that cause such events, assess their geochemical significance, and provide both analytical and predictive capabilities for observations on greater temporal and spatial scales.