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In the overall strategy of national security, the pelagic clustering islands as an important fulcrum and platform to safeguard national coastal defense and maritime rights and interests, has a special geostrategic significance. Reliable energy supply is the artery of the development and construction of the pelagic clustering islands, but the current research is mostly aimed at the offshore islands, lacking of relevant theories and methods for the pelagic islands. Therefore, the current situation of the island grid research and its limitations and defects when applied to the pelagic clustering islands are inquired and analyzed in the article firstly. Furthermore, integrated energy supply system of pelagic islands is proposed for the purpose of taking full advantage of the islands' abundant renewable energy to optimize the configuration of resources of the islands group as a whole and sustainable development. The integrated energy supply system breaks the isolated development pattern of island grid, taking the islands group as a whole interconnected through the originality energy storage (exchange) vessels. Then, the content and features of the system is analyzed. Finally, the key technologies required to construct the integrated energy supply system of pelagic islands group are summarized, and the design of electrical storage vessels and the analysis of their operation scene is given, in order to provide a reference for the development and construction of China's pelagic islands.
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... At present, island power supply mainly depends on diesel generators or the connection with mainland power grid. High cost, poor reliability, environmental pollution and other adverse factors greatly limit the further development of island microgrid . Hybrid renewable energy system is a promising technology for clean and sustainable island power supply. ...
The hybrid renewable energy system is a promising and significant technology for clean and sustainable island power supply. Among the abundant ocean energy sources, tidal current energy appears to be very valuable due to its excellent predictability and stability, particularly compared with the intermittent wind and solar energy. In this paper, an island hybrid energy microgrid composed of photovoltaic, wind, tidal current, battery and diesel is constructed according to the actual energy sources. A sizing optimization method based on improved multi-objective grey wolf optimizer (IMOGWO) is presented to optimize the hybrid energy system. The proposed method is applied to determine the optimal system size, which is a multi-objective problem including the minimization of annualized cost of system (CACS) and deficiency of power supply probability (DPSP). MATLAB software is utilized to program and simulate the hybrid energy system. Optimization results confirm that IMOGWO is feasible to optimally size the system, and the energy management strategy effectively matches the requirements of system operation. Furthermore, comparison of hybrid systems with and without tidal current turbines is undertaken to confirm that the utilization of tidal current turbines can contribute to enhancing system reliability and reducing system investment, especially in areas with abundant tidal energy sources.
... The optimization objective, shown in eq. (20), is to minimize the freight cost of carpooling and 324 punishment for not supplying enough battery. 325 ...
High share of variable renewable energy is challenging to the traditional power system technically and economically. This calls for a significant increase to the system flexibility, which might result in the costs associated with energy storage and costly upgrades to the traditional transmission and distribution system. This paper presents a multi-stage battery transportation and logistics optimization method to increase the renewable energy consumptions, economics, and mobilities of the battery utilization. A new approach is proposed in which the batteries are charged in the renewable power plants and transported back and forth by railways between the renewable power plants and cities. Based on the forecasts of battery supplies/demands, multiple optimization stages (full train transport and carpooling) are designed by the branch-and-bound algorithm and genetic algorithm respectively. The proposed battery transportation and logistics concept and model are performed using the Beijing-Tianjin-Hebei region in China as an example. The results show that the levelized cost of energy of the battery transportation and logistics model is $0.045/kWh averagely. Also, by the use of mobilized batteries, the proposed battery transportation and logistics model increases the system flexibilities and renewable energy deliveries to the end users without the reinforcement of transmission and distribution system and any constraint from a highly penetrated power system.
Studies have demonstrated that using offshore mobile energy storage, i.e., all-electric-ships (AESs) equipped with energy storage batteries, for the energy sharing of multi-island microgrids (MIMGs), may be a more economical approach than laying submarine cables. However, given the individual interests, privacy protection demands, and participation willingness of AESs and MIMGs, existing energy sharing strategies are not suitable for such a specific scenario. To address these issues, this paper proposes a novel energy cooperation coalition comprised of an energy transmission provider (ETP) and MIMGs, where ETP is not only an initiator of the coalition but also an operator for the inter-island energy sharing using its AESs. Furthermore, the energy cooperation problem, including AES’s spatial–temporal coupling model, is reformulated into a two-stage problem of energy scheduling and benefit allocation, and is optimized in a distributed way. Then, an original adaptive enhanced constraint-alternating direction method of multipliers is presented to solve the energy scheduling problem for better convergence. A bi-level benefit allocation mechanism based on asymmetric Nash bargaining is also devised, with a role and energy-based contribution rate and a bilateral incentive strategy to evaluate contributions and ensure cooperative willingness. Finally, numerical simulations verify the effectiveness of the suggested energy cooperation coalition, distributed optimization method, and benefit allocation mechanism.
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.
Pelagic islanded microgrid groups (PIMGGs) can be developed into resource islands and load islands with the electric vessel achieving the interisland energy transmission. For such multi-microgrid structure, the interisland energy transmission time affected by environmental factors is likely to be non-integer hour (such as 23min), resulting in mismatching with the standard day-ahead scheduling step (1h). However, rounding the transit time may bring about large errors in optimization results, while using an elaborate scheduling step to approach the transit time will result in heavy computing burden due to numerous variables. To address the above problems, this paper proposes a novel dayahead energy management system (EMS). Firstly, analyzing the impact of environmental factors including wind, ocean current, and wave, a centralized energy management framework considering the non-integer-hour energy transmission is designed. Furthermore, an optimal EMS operation model based on the 1-hour scheduling step is proposed. It eliminates the errors from rounding by coordinating the original and mirror unit commitments. Additionally, the optimization model is converted into a mixed-integer linearization programming (MILP) problem using a two-stage method including preprocessing and linearizing stage. Simulation studies on Taiping Island, Honma Island and Bolan Reef indicate the proposed EMS is effective and beneficial for PIMGGs.
The pelagic clustering islands (PCIs) can be developed into the resource rich islands (RRIs) and load center island (LCI) using the electric vessel (EV) to achieve interisland energy flow. However, energy balance between the supply and demand cannot be directly achieved, resulting in crucial need for effective day-ahead energy management for PCIs. To address this issue, this paper proposes a novel scenario-based energy management system (EMS) to optimize the operation of PCIs. To ensure the EMS performance, the comprehensive impact of environmental factors including wind, solar radiation and ocean currents on energy supply, transmission and demand is analysed in detail. The dynamic energy transmission channel and power flow balance relationship are modelled by evaluating the location and charging/discharging power of the EV. Considering the forecasting inaccuracies in environmental factors using refined stratified sampling (RSS) and scenario reduction methods, a stochastic optimization model is proposed to maximize the operational economy and reliability of PCIs, followed by a 2-stage solution consisting of preprocessing and group-search optimization with multiple producers (GSOMP). Simulation studies on Taiping Island, Hongma Island, Bolan Reef and Anda Reef in the South China Sea show that the proposed EMS is feasible and economical to describe the energy supply of PCIs.
Reliable energy supply is the artery for the development and construction of island. The off-grid island microgrid model using renewable energy and diesel generator has been paid more and more attention, and the topology of island microgrid is the basis of studying island microgrid. This paper analysises the influencing factors of topological structure design of island microgrid and designs two kinds of island microgrid topology structure. Using Minimum Cut Set Method, this paper compaperd the reliability of the new microgrid topology with the existing topology of off-grid island AC microgrid and studied the influence of the ratio of AC and DC loads on the reliability of the system. Also, this paper points out the scope of application for each microgrid topology. The results can provide some references for the topology design of the island microgrid.