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distributed system and other equipment should not disturb generators. The zonal architecture is flexible and saves the cost for short switchboard feeder cables and elimination of distribution transformers. A zonal distribution system also allows for equipment installation and testing prior to zone assembly [46]. Need for Reconfiguration Faults in a shipboard power system may occur due to material casualties of individual loads or widespread fault due to battle damage. In addi‐ tion to load faults, casualties can happen to ca‐ bles, power generating equipment, or power distribution buses. If the fault is severe, such as a generator fault, it may cause a power deficiency to the remaining power system, system load generation unbalance, and even an entire sys‐ tem collapse. After the fault has occurred, pro‐ tective devices operate to isolate the faulted section. But, this may lead to unfaulted sections that are not getting supplied. Therefore, it is re‐ quired to restore supply automatically and quickly to these un‐faulted sections of the ship‐ board power system to improve the system sur‐ vivability. This can be achieved by changing the configuration of the system by opening and/or closing switches to restore supply to maximum load in the un‐faulted sections of the shipboard power system. Reconfiguration can be aimed at supplying power to high priority loads and/or supplying power to maximum amount of loads depending upon the situation. The need recon‐ figuration is also proposed to maintain power balance of the remaining power system parts after fault detection and isolation. Fast recon‐ figuration is necessary for a shipboard power system considering the unique shipboard power system characteristics. Methodologies Reviews In recent years, several reconfiguration method‐ MIMET Technical Bulletin Volume 1 (2) 2010 ologies have been proposed for power systems. With the advancement in the power system, the topology of power systems has become more complicated. However, in previous reconfigura‐ tion methodologies, no generic methodology was proposed for the reconfiguration of a power sys‐ tem with a complicated topology. Most of the previous reconfiguration methodologies are to‐ pology dependent. New reconfiguration method‐ ologies need to be researched and developed for power systems with large scale and complicated topologies [44]. There are slight differences between reconfigu‐ ration of terrestrial power system and shipboard power system. Reconfiguration of terrestrial power system The reconfiguration approach for power system can be implemented in centralized manner or in decentralized manner. In centralized approach, various methods are applied to the reconfigura‐ tion approach, such as evolutionary program‐ ming, heuristic method, artificial intelligent method, etc. The main advantage of the centralized ap‐ proaches for power system reconfiguration is that it is easy for the central controller to access re‐ quired information for reconfiguration reasoning. The central controller in a centralized approach can directly gather data from the sensors throughout the entire system. When there are changes in the system, the central controller can easily update its database for reconfigura‐ tion. The disadvantage of the centralized ap‐ proach for reconfiguration is that it may lead to the single point of failure in the system if the system lacks redundancy. The main advantage of the decentralized ap‐ proach for power system reconfiguration is the robustness. The decentralized approach is im‐ | MARINE FRONTIER @ UniKL 87
mune to the single point of failure because there is no central controller in the approach. Also the decentralized approach has more flexi‐ bility and scalability compared to the central‐ ized approach. However, the controllers in the decentralized system have limited access to the information of the system for control decisions. So, compared to the centralized approach, it is harder for the decentralized system to achieve the global optimal solution based on the limited information each controller has. Many of the proposed automatic reconfiguration methodologies are developed for distribution system reconfiguration. The distribution system is usually reconfigured for restoring the loads in the distribution system, decreasing the power loss in the distribution system, stabilizing the distribution system, etc. Schmidt et al [3] put forward a fast integer pro‐ gramming based reconfiguration methodology to minimize the power loss in a distribution sys‐ tem. The power loss in the distribution system is the electric power that is consumed by transmis‐ sion equipments, such as transformers, cables, wires, etc. This methodology is only applicable to radial power systems. Tzeng et al [4] proposed a feeder reconfiguration methodology for the distribution system. In that particular research, dynamic programming is used to find the optimal switching actions for load balancing in a distribution system. In a power system, the loads get electric power sup‐ ply from load feeders. The load feeders that sup‐ plies more loads need more current injections than those load feeder supplying lesser loads. This will cause the imbalanced current distribu‐ tion in the power system. With the same loads supplied in the power system, the imbalanced current distribution in the power system leads to more power loss than balanced current distribu‐ tion in the power system. The imbalanced cur‐ MIMET Technical Bulletin Volume 1 (2) 2010 rent in the power system also leads to the over current problem and stability problem. The load feeders in the power system need to be bal‐ anced by switching the circuit breakers and other switching devices so that the current dis‐ tribution in the power system can be balanced.. Gomes et al [5] proposed a heuristic reconfigura‐ tion methodology to reduce the power loss in a distribution system. In this work, the optimal power flow and sensitivity analysis are used to find the reconfiguration solution. This reconfigu‐ ration methodology is only applicable to radial power systems. Hsu et al [6] proposed a reconfiguration method‐ ology for transformer and feeder load balancing in a distribution system. When the number of loads that are supplied through a load feeder increases, the current injection to the load feeder increases. The current that flows through the transformer is connected to the load feeder increases, too. It may lead to the risk of over cur‐ rent on the transformers and the transmission lines in the system. The proposed reconfigura‐ tion methodology is based on heuristic search. Another heuristic search based reconfiguration algorithm was proposed by Wu et al [51]. In the research, the reconfiguration methodology was applied to the radial power system for service restoration, load balancing, and maintenance of the power system. Zhou, et al [7] put forward a heuristic reconfiguration methodology for distri‐ bution system to reduce the operating cost in a real time operation environment. The operation cost in the power system is the power loss in the distribution system. The operation cost reduc‐ tion is based on the long term operation of the power system. The knowledge based systems, such as expert systems, have also been applied to the recon‐ figuration of power systems for a long time. | MARINE FRONTIER @ UniKL 88
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EDITORIAL CHIEF EDITOR Prof. Dato
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DIRECTIONAL STABILITY ANALYSIS IN S
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The determinant from equations (3)
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Table 1 ‐ Results of Stability Cr
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DO 20 J=1,7 REFF(J)=1+((J‐1)*1.5/
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Skeg Effectiveness Skeg Effectivene
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Skeg Effectiveness Skeg Effectivene
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A WATER FUELLED ENGINE FOR FUTURE M
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Stainless steel pipes are used as e
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Current development Hydrogen Oceanj
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Car industry A small group of local
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Big oil companies. For business sur
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Websites: 1. http://www.schatzlab.o
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Table 1: Global maritime Fleet Rank
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No. of Ships No. of Ships 300 250 2
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time players is 30. The demand for
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References [1] UNCTAD, Review Marit
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Table 3 : Tug boat Registered in Ma
Page 38 and 39: NO SHIP NAME OWNER/OPERATOR GRT DWT
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Page 54 and 55: Table 8 : Tankers Registered in Mal
Page 58 and 59: Table 10: Passenger Ship Registered
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Page 64 and 65: age and appropriate steps must be t
Page 66 and 67: tends to oxidize rapidly, even at a
Page 68 and 69: oxide or other anti‐oxidant addit
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Page 76 and 77: Objective of the Research The resea
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Page 80 and 81: Mean Median Table 3.1: Carrier Aspe
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Page 86 and 87: adversely affecting ship operations
Page 90 and 91: Knowledge based system is a compute
Page 92 and 93: Again Butler and Sarma [28] put for
Page 94 and 95: particle swarm optimization (PSO)[1
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Page 102 and 103: Table 2. Measurements for Integrity
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Page 106 and 107: have become a major issue without m
Page 108 and 109: used to model the pneumatic transmi
Page 110 and 111: Figure 2: Transmission Line Diamete
Page 112 and 113: PDE equations (1) and (2). Comparis
Page 116 and 117: Since chemical products have high p
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