Load Flow Simulation of Radial Shipboard Network Structure with Direct Current Distribution Systems

The aim of this research is to investigate load flow of direct current distribution system on trimaran ferry ship. Radial Shipboard Network Structure with Direct Current Distribution Systems has been proposed in this research. Load flow simulation has been done by calculating electrical load calculation based on ship operation. Then, the one-line diagram of direct current distribution system is developed on electric power software. Simulation results show that direct current distribution system has been successfully implemented on hybrid powered trimaran Ship. In sailing conditions, the overall real power requirement is 20,201 MW and the reactive power is 7,757 Mvar. While the power distributed is 20,493 MW of real power and 7.816 Mvar of reactive power. In manoeuvring conditions, the actual power requirements are 21,251 MW and the reactive power is 8,16 Mvar and for power distributed is 21,573 MW of real power and 8,224 Mvar of reactive power. In loading and unloading conditions, the actual power requirements in this operating condition are 0.616 MW and the reactive power is 0.292 Mvar and for power distributed is 0,635 MW of real power and 0,296 Mvar of reactive power. In the condition of entering the port, the required power is 12.906 MW for real power and 4.969 MW for reactive power and for power distributed is 13,027 MW of real power and 4,994 Mvar of reactive power. The result showed that the concept direct current distribution system has been successfully developed in this research to combine diesel generators with marine renewable energy to make sure that the distributed power stay adequate all through operation.

The concept of DC distribution system is believed to minimise the failure of HPS [4]. In terms of equipment, DC distribution systems have advantages over AC distribution systems [5]. In DC network, switchgears and large transformers are not used, so it provides benefits such as space and weight savings, and flexible equipment management especially on ships that have limited space. In addition, DC power distribution does not require synchronization of generating units, dc power systems allow prime movers to operate at their optimal speed, and lead to significant fuel savings [6] [7].
DC distribution system concept offered is AC voltage from the diesel generator will be converted into DC voltage by the rectifier. then, the electric power is controlled through the DC-DC Converter to maintain voltage stability [8]. Then the electric power is transmitted to each electricity load using DC current. Before entering each load, the DC current will be converted into AC current by the inverter, see figure 1. In this research, it concerned about investigating of power flow analysis on DC distribution system. Trimaran ferry ship use a combined source of electricity in the form of diesel generators and batteries. Both of main electrical source are used together to meet the electricity needs of the trimaran ship according to the operating conditions of the ship.
The flow analysis is carried out with several scenarios combining diesel generators and batteries based on ship operations namely sailing, manoeuvring, loading, and unloading and at the port. the procedure for carrying out power flow simulations begins with calculating the electrical load in each operating condition of the ship, then determining the power capacity by selecting an electric power source. After that, modelling the DC distribution system in electric power software.

Proposed Dc Power Distribution System Framework
The change from AC power distribution system to DC is done by rectifier and converter dc to dc. The configuration used from the onboard DC grid uses a fully distributed system. In a fully distributed system, each converter is near an electric generator [9] [10].
In the port entry condition, the minimum electricity demand that must be available is 13,112.96 kW. To meet the class requirements, in this operating condition the generators available are generators with 5000 kW of power, 3 generators with a load factor of 0.87 must be provided. For generators with power of 5700 kW, 7030 kW and 8200 kW, there must be 3 generators with load factors of 0.77, 0.62 and 0.53, respectively. For ship operations in loading and unloading conditions, the total power needed is 542.17 kW. If minimum power is supplied by 1 generator at each capacity. Generator load factor between 0.07 to 0.11. By looking at the facts above, the generator was chosen with a power capacity of 5,700 kW. The basis for selecting a generator is under sail conditions, a generator with a capacity of 5700 kW has a load factor of 0.90 even though class requirements require a maximum load factor of 0.86. To meet class requirements the power shortage will be fulfilled by adding 1,500 kW of battery.

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The use of four generators with 5700 kW power does not meet the class requirements that the power that must be available on the ship is 15% more than the total power requirements under operating conditions. Therefore, trimaran passenger ships are planned to use hybrid electricity by combining the power generated by the generator with the battery. The use of four generators with 5700 kW power does not meet the class requirements that the power that must be available on the ship is 15% more than the total power requirements under operating conditions. To meet the classification requirements an additional power of 1000 kW is required. Therefore, trimaran passenger ships are planned to use hybrid electricity by combining the power generated by the generator with the battery.
The procedure in calculating Ampere Hour of batteries needed is by determining the amount of energy (Watt hours) then determining the ampere hour. The amount of energy needed is calculated from the power requirement of 1500 kW multiplied by the time of battery usage, as shown in equation 1.
The application of hybrid electric power between diesel generators and batteries in sailing conditions meets class requirements where there is 15 percent more power when compared to the total power requirements during sailing conditions, as shown in table 4. In sailing conditions, 4 sets of diesel generators are used with each power capacity of 5700 kW and as many as 3 sets of batteries with a voltage of 690 VDC with an Ampere hour of 3550 AH. This hybrid electric power is used only during sailing conditions while in maneuvering conditions and the condition at the power plant port is fully diesel generator. For maneuvering, 5 sets of generators are used with a load factor of 0.76, while in the harbor, 3 sets of generators are used with a load factor of 0.77. And in the loading and unloading operating conditions, the electricity supply is carried out entirely by a two battery with a voltage of 690 VDC with an ampere hour of 3550 AH.  .,&9.43 .,-9.3, :3(9.43 7.),* *(0 :3(9.43 .,-9.3, &7 *(0 :3(9.43 .,-9.3, 7*< *(0 :3(9.43 .,-9.3, :3(9.43 .,-9.3, &88 *(0 *6:. In figure 6 shows that the load profile of machinery system. For Aux Cool Hydraulic equipment, the power distributed is 39.37 kW of real power and 20.03 kVar of reactive power during sailing conditions, 46.32 kW of real power and 23.56 kVar of reactive power during maneuver conditions and 16.21 kW real power and 8.25 kVar reactive power when conditions enter the port. Meanwhile, when loading and unloading, Aux Cool Hydraulic equipment is not powered. Then, Aux Motor Hydraulic equipment, the power distributed is 19.68 kW of real power and 9.35 kV reactive power during sailing conditions, 19.47 kW of real power and 11 kVar of reactive power during maneuvering conditions and 6.82 kW of power real and 3.85 kVar reactive power when conditions enter the port. Whereas when loading and unloading, Aux Motor Hydraulic equipment is not powered. For FW Hydrophore equipment, the actual power distributed under sailing, maneuvering, loading and unloading and port entry conditions is 2.68 kW. And the reactive power distributed in sailing, maneuvering, loading and unloading conditions and entering the port is 1.71 kVar.
For FW Pump equipment, the actual power distributed under sailing, maneuvering and unloading conditions is 19.68 kW. And the reactive power distributed in the conditions of sailing, maneuvering, loading and unloading and entering ports is 10.91 kVar. While entering the port, the power received by the equipment / load is 9.84 kW of real power and 5.45 kVar of reactive power. For Motor Pre-Lubricating equipment. Pump and Motor Start, the power distributed is 67.11 kW and 33.55 kW real power, for reactive power is 35.84 kVar and 19.41 kVar in all ship operating conditions. As for the OWS, SW Hydrophore and SW Pump equipment, the power distributed is 8.95 kW, 2.68 kW and 19.68 kW real power, for reactive power is 5.01 kVar, 1.71kVar and 10.91 kVar at all ship operating conditions.
For Oily Bilge Pump equipment, real power is distributed under sailing conditions, and maneuvering conditions of 9.84 kW of real power and 5.89 reactive power. And the condition of loading and unloading and entering the port, the power transmitted is 4.92 kW of real power and 2.94 kVar of reactive power. The graph of the machinery system load panel to the machining system equipment is shown in Figure 6 for real power.
In figure 7 shows that the load profile of deck machinery such as AHU equipment, Capstan, E / R Vent, Motor Ramp Door, Prov. Crane and Windlass. For AHU equipment, the received power is 13.42 kW of real power and 7.17 kVar of reactive power under sail and maneuver conditions. While in loading and unloading conditions, the received power is 12.63 kW of real power and 6.75 kVar of reactive power. And on the condition of entering the port, the received power is 25.26 kW of real power and 13.49 kVar of reactive power. For Capstan equipment, the received power is 26.84 kW of real power and 14.33 kVar of reactive power in sailing and maneuvering conditions. While at loading and unloading conditions and entering the port, the received power is 37.89 kW of real power and 17.45 kVar of reactive power. The load profile of Refrigeration and Ventilation is shown in figure 8. Bridge Deck Exhaust Fan and Bridge Deck Sup Fan equipment, the received power is 1.05 kW and 1.58 kW for real power. As for the reactive power of 0.854 kVar and 1.28 kVar in sailing, maneuvering and loading and unloading conditions. And on the condition of entering the port, the received power is 0.99 kW and 1.49 kW real power and 0.803 kVar and 1.21 kVar reactive power.
For Car Deck Exhaust Fan and Car Deck Supply Fan equipment, the received power is 2.1 kW and 3.16 kW for real power. As for the reactive power of 1.71 kVar and 2.56 kVar in sailing, maneuvering and loading and unloading conditions. And on the condition of entering the port, the received power is 2.97 kW and 5.94 kW real power and 1.61 kVar and 2.41 kVar reactive power.
For Crew Deck Exhaust Fan and Crew Deck Supply Fan equipment, the received power is 6.31 kW and 17.88 kW for real power. As for the reactive power of 5.12 kVar and 14.51 kVar in sailing, maneuvering and loading and unloading conditions. And at the condition of entering the port, the received power is 5.94 kW and 16.83 kW of real power and 4.82 kVar and 13.66 kVar reactive power.
For E / R Deck Exhaust Fan and E / R Deck Supply Fan equipment, the received power is 0.526 kW and 0.526 kW for real power. As for the reactive power of 0.427 kVar and 0.427 kVar in sailing, maneuvering, loading and unloading conditions and entering the port.
For Pass Deck Exhaust Fan and Pass Deck Supply Fan equipment, the received power is 2.1 kW and 7.36 kW for real power. As for the reactive power of 1.71 kVar and 5.98 kVar in sailing, maneuvering and loading and unloading conditions. And on the condition of entering the port, the received power is 1.98 kW and 6.93 kW is real power and 1.

Distributed Power
Under sailing conditions, the overall real power requirement is 20.201 MW and reactive power is 7.757 Mvar. The availability of electric power is adequate and meets the class requirements in sailing conditions i.e. power is supplied by 4 (four) diesel generators and 17750 AH diesel batteries as shown in table 4. The total available power is 24.3 MW consisting of 22.8 MW which produced by 4 (four) diesel generators and 1.5 MW of batteries, see table 4. Table 4 shows that the power distributed to each generator is 4.845 MW for real power (P) and 3.634 Mvar (Q) for reactive power. With the current and load factors in each generator are 317.9 and 85 percent. while the batteries are distributed at 1.5 MW every one hour.
In maneuvering conditions, the actual power requirements are 21.251 MW and the reactive power is 8.16 Mvar. The availability of electric power is supplied by 5 (five) diesel generators which are shown in table 4. The total available power is 28.5 MW. Table 4 shows that the total distributed power was 4.845 MW for real power (P) and 3.634 Mvar (Q) for reactive power. With the current and load factors in each generator are 317.9 and 85 percent.
Furthermore, for loading and unloading conditions, the actual power requirements in this operating condition are 0.616 MW and the reactive power is 0.292 Mvar. The electricity demand in this loading and unloading condition will be supplied by a 1.5 MW battery capacity. With a battery capacity as shown in table 4, a battery can last 2 hours. For the condition of entering the port (at port), the required power is 12.906 MW for real power and 4.969 MW for reactive power. Power requirements will be fulfilled by supplying electrical energy from 3 (three) diesel generators as shown in table 5.

Sufficient electricity
Simulation results for power distribution under ship operating conditions are shown in Figure 10. The available power for each condition meets class requirements. In each operating condition, the load factor of each generator is 85%, with a generator capacity of 5700 kW or 7125kVA distributing real power of 4845 kW and reactive power of 3634 kVAR. Figure 5 shows that the available power capacity is greater than the power needed in each operating condition. The power distributed and transmitted to the direct current electricity network is 85% (eighty-five percent) of the available power at sailing conditions, maneuvering conditions and port entry conditions. Whereas in loading and unloading conditions, battery life in distributing electrical energy only lasts for 2 hours. And the amount of power distributed is greater than the power needed to operate in each condition.

Conclusion
The application of the DC distribution system for hybrid power trimaran ship has been successfully implemented. The use of hybrid electric energy sources namely diesel generators and batteries has been well simulated. Power simulations show that batteries make an important power contribution in sailing conditions. This additional power has increased the diesel generator load factor performance from 90% without batteries to 86% with batteries. In the power flow simulation, it is known that in sailing conditions, the overall real power requirement is 20,638 MW and the reactive power is 7,971 Mvar. The availability of electric power is adequate and meets the class requirements in sailing conditions that is power supplied by 4 (four) diesel generators and 17750 AH diesel batteries. In maneuvering conditions, the actual power requirements are 21,722 MW and the reactive power is 8,389 Mvar. The availability of electric power is supplied by 5 (five) diesel generators. And in loading and unloading conditions, the actual power requirements in this operating condition are 0.638 MW and the reactive power is 0.31 Mvar. The electricity demand in this loading and unloading condition will be supplied by a 1.5 MW power capacity battery. For the condition of entering the port (at port), the required power is 13.119 MW for real power and 5.078 MW for reactive power. Power requirements will be fulfilled by supplying electrical energy from 3 (three) diesel generators.
The characteristics of equipment power flow on the ship's main drive bus panel indicate that the greatest power is in maneuvering conditions. After that, followed by sailing conditions, conditions of entering the port and loading and unloading conditions. In the machining system panel, the power flow characteristics are almost the same as the main driving bus panel of the ship where the greatest power is in a maneuver condition. After that, followed by sailing conditions, conditions of entering the port and loading and unloading conditions. Whereas on the deck machined bus panels, the characteristics of the power flow are in sailing and maneuvering conditions, the flow of power to the equipment is almost the same. Similarly, the loading and unloading conditions and entering the port. Furthermore, for the refrigeration and ventilation bus panels, the characteristics of the power flow are in the sailing, maneuvering and loading and unloading conditions of the power flow to the equipment is almost the same. While in the condition of entering the port, the power flow is lower. 7</::G =< #/D =; >/<3:A /<2 :756B7<5 B63 >=E3@ 4:=E 16/@/1B3@7AB71A /@3 B63 A/;3 4=@ /:: A67> =>3@/B7<5 1=<27B7=<A