A fully electrical tug system comprising an integrated propulsion system and power generation system

Abstract

The invention is related to a zero-emission, fully electrical tug system which is used in harbour operations, and which comprises an integrated propulsion system and power generation system to maximize useful lifetime of batteries which provide energy efficiency, and which are energy storage units and to store regenerative energy in said batteries and to be able to use it if necessary.

Description

[0001] A FULLY ELECTRICAL TUG SYSTEM COMPRISING AN INTEGRATED PROPULSION SYSTEM AND POWER GENERATION SYSTEM

[0002] Technical Field

[0003] The invention is related to a zero-emission, fully electrical tug system which is used in harbour operations, and which comprises an integrated propulsion system and power generation system to maximize useful lifetime of batteries which provide energy efficiency and which are energy storage units and to store regenerative energy in said batteries and to be able to use it if necessary.

[0004] Prior Art

[0005] Recently, as in all fields, also in the maritime sector, the issues of efficiency in energy usage, environmental effects of fossil fuel usage, construction and then operational costs of marine vessels have great importance. In recent years, concerns related to global warming and emissions all over the world causes the demand of environmentally friendly energy need to quite increase. In the maritime sector, in the International Maritime Organization, regulations are applied to ships for decreasing NOx and SOx emissions and maximum efficiency in accordance with MARPOL 1. According to the goals of 2050 of the IMO (the International Maritime Organization), it is foreseen that emissions of greenhouse gas in the maritime sector will be decreased at least 50% independently of growth in the trade volume. To be able to achieve this goal will be provided only by 90% increasing the energy efficiency in the industry. This means that fossil fuels will not be able to be used in the long term.

[0006] Besides, fossil fuel which we can define as traditional, and which is the only energy source for ships cannot meet the needs of the sector anymore. In the ships used at the state of the art, all energy need of the ships including propeller thrust and electrical loads is met by petroleum derived fossil fuels. In general, heavy petroleum derived fuels such as MDO (marine diesel oil) and HFO (heavy fuel oil) are burned by internal combustion motors and the generated mechanical power is transmitted to propellers or electric generators. Said marine type fuels have quite low quality compared to the fuels used in land vehicles because of financial concerns and their emissions of SOx, NOx, COx and PM are high.

[0007] Also, because of fuel costs increasing approximately 50% which is one of the biggest problems in the maritime sector and obligations needed to be obeyed related to emissions, IMO (international maritime organization) has entered into force as from 01.01.2020. These conventional systems which did not even have an alternative in the sector until five years ago cannot meet the emission restrictions recently entering into force anymore. These emission restrictions bring major limitations to sulphurous gases and other greenhouse gases ships may release during its operation. Especially, North Europe countries have set quite ambitious targets to decrease release of harmful gases caused by the maritime sector. According to the projections made by the maritime authorities, if the current trend in the market continues unchanged, the level of emission in 2040 will be 60% more than one in 2015. To be able to reach the current emission targets, it is a must that alternative fuels, energy storage systems, alternative propeller propulsion systems and generally more efficient power systems are put into practice.

[0008] International authorities such as IMO (International Maritime Organization), ICS (International Chamber of Shipping) take precautions affecting entire world. Besides, the European Union and maritime authorities of countries take their own precautions. The common point of all regulations is that they require innovative fuels and systems to stay under the limitations. For ship owners and operators, this means that if they do not update their fleet, their firms will not be able to continue their operation within 10-20 years.

[0009] Besides, the average annual fuel cost of a ship is approximately 2.4 times the cost of ship construction. Because of increasing number of harbours requiring zero emission and / or low emission, R&D studies made for decreasing emissions and fuel savings of tugs operating especially in harbour zones have great importance.

[0010] Tugs are ships which have the ability of responding urgently to large ships which have oil and petroleum leakages and fires in said ships, in addition to these, have the ability of saving / pushing / pulling ships in other situations, have the feature of piloting large ships, have 40 tons pushing / pulling power. In all these operations, pushing power a ship needs and speed which it should move with are different. So, it directly changes the load on the main engine and prevents it from being operated at the optimum efficiency.

[0011] Ships which operate at harbours and coastal regions such as tugs are subjected to stricter emission limitations than other ships. Therefore, it is easily understood that they are type of ships which are affected more by aforementioned regulations. Due to this, continuously increasing restrictions against emissions are a growing source of concern for tug owners and operators. It is obvious that harbour operators will not be able to continue their firm operations with their current fleets in the near future and need innovative solutions.

[0012] Generally, marine type internal combustion motors are optimized such that they operate with the maximum efficiency at 80% MCR (maximum continuous rating) loading. The reason for decreasing of efficiency is that internal combustion motors do not operate with the same efficiency at every loading. On the contrary, at loadings under 50%, machine efficiency decreases considerably. Because propulsion systems are same in hybrid and conventional systems, this situation applies to both of two systems. In addition to this, electric networks of conventional systems are energized by diesel generators. In ships which are subjected to variable loads such as tugs, these generators feeding the power system are affected by variable loading conditions. In an example embodiment, it is assumed that electrical power need of a ship changes between 500 and 1100 kW and its average power need is 800 kW. This ship having a conventional system has 2 auxiliary generators of 1000 kW. Even if its average power need stays under the capacity of 1 generator, this ship cannot operate by running 1 generator because its power need sometimes increases above 1000 kW. Otherwise, it is possible that the generator is overloaded and blackout of the ship. When 2 generators are operated in parallel, each generator is loaded 40% (400 kW) on average. This situation causes the generator to burn fuel more inefficiently. Therefore, hybrid systems having batteries are more advantageous than conventional systems. One way to decrease disadvantages of conventional systems said above is to develop hybrid systems, more importantly efficient hybrid systems. In the example given above, if a power generation system having batteries inside is added to 2 generators of 1000 kW, it will become possible that the ship is operated with 1 generator instead of 2. While the generator carries the longterm average load, the batteries will meet short-term load fluctuations which may cause said generator to be overloaded. Due to this, loading of generators which is 40% in the conventional system is increased to 80% with the hybrid system. On average, while 2 generators consume 170 kg / h fuel with 40% loading, 1 generator consumes 146 kg / h fuel with 80% loading. With the hybrid system, periodical maintenance costs are prevented by decreasing operating hours of generators besides approximately 14% fuel saving in total. However, there are still problems in the hybrid systems. Driving a propeller called as mechanical drive system in the maritime sector directly with internal combustion motors is a disadvantageous situation especially in the ships subjected to variable loads such as tugs. This type of mechanical drive system does not have a big problem in terms of energy efficiency for the ships travelling with constant speed at 99% of their operation profiles such as long-distance tankers, cargo ships. However, efficiency decreases when main engine driven propeller systems are directly used for the ships which have very variable operation profiles such as tugs. Therefore, various improvements should be done when switching to fully electrical systems to prevent this efficiency from decreasing.

[0013] In addition, variable operation profile means variable propeller load profile. Because the internal combustion motors subjected to variable loads bum fuel less efficiently with low loading, their fuel costs and emission rates increase. In addition to decreasing efficiency with low loading, amounts of emission released per unit fuel also directly depend on loading rates at the same time (Figure-1). In the Figure 1, a specific fuel oil consumption (SFOC) curve with respect to loading rates of a ship type at the state of the art is given for a standard 4- stroke internal combustion motor. While X axis shows machine load in terms of MCR% (maximum continuous rating), Y axis shows how many grams of fuel should be burned to release 1 kWh of mechanical energy. As seen, marine type internal combustion diesel motors have been designed such that they operate in the most efficient way with around 80% loading. Especially with loadings under 55%, SFOC, therefore efficiency, decreases dramatically. The main engine connected to the mechanical propulsion system and the auxiliary generators connected to the network in said conventional systems also show a characteristic as in the Figure-1.

[0014] One of the reasons for inefficient fuel consumption is that the load on the main engine is variable at wavy seas. The main engine is forced to operate in the inefficient zone because of fluctuating profile of the propeller load. The propeller load of the ships which have variable operation profile such as tugs is constantly changing. This means that main engines will spend their lifetime out of the zone of the optimum efficiency. This situation becomes more prominent especially in the ships where the ratio of the average power consumption (or spent power) to the installed power (or provided power) is small such as tugs. Besides not being constant of the operation profile, bad weather conditions also may quite decrease the efficiency of the main engine. The propeller of the ship is also possible to sink and float in the water together with waves at a wavy sea. Physical effect of said sinking and floating motion in the water on the propeller means that the propeller load changes over time. Every time the propeller sinks in the water, the load on the propeller and main engine increases. When the propeller gets out of the water, an opposite situation comes up and the load on the engine operating under high load suddenly decreases. As a result of this periodical motion, it has been determined that the load of the main engine changes between 20%-80% MCR (maximum continuous rating). The result said load fluctuation results in is to burn fuel in a bad and inefficient way. The auxiliary generators are very inefficient in cases that more than one generator is required to be operated to provide backup at the network. When considered only in terms of power calculation, it is required to distribute a load 1 generator can meet to 2 generators to provide backup and to be protected from load fluctuations. This causes the fuel amount burned to increase, even if the amount of the electrical energy produced is same. Also, the curves of specific gas release of internal combustion motors with respect to loading are parallel to the SFOC curve in the Figure-1. Internal combustion motors burn fuel in a “worse” way with low loads, namely, amounts of gas released per unit energy released increase.

[0015] The images of the conventional and hybrid systems are given respectively in Figure 1 and Figure 2. Propulsion systems and power generation systems of the conventional and hybrid systems are very similar to each other. The difference of the hybrid system from the conventional system is that an energy storage system is integrated to the power network.

[0016] Besides, hybrid systems vary within themselves. Propulsion systems and power generation systems can be hybridized by using different topologies. The hybrid structure which will be predicated on in comparison allows at least one generator to operate more efficiently by adding at least one battery to the power generation system. The reason why this hybrid structure is selected for comparisons is that it is a structure which is suitable for tugs, has a low investment cost. The batteries at the network of the hybrid structure allow at least one generator to be loaded with higher rates.

[0017] In both of conventional and hybrid systems, the propulsion system and power generation system of the ship are produced independently from each other. The thrust the ship needs is met by the main engines connected to the propeller and the ship’s need for electrical energy is met by the auxiliary generators connected to the AC network, if needed. At the state of the art, because propeller drive systems and power generation systems are the subjects requiring different specialties, these systems are developed by different firms, this causes harmony-based problems in all electric and automation systems of the ship. Therefore, an integrated propulsion system (or propeller) and power generation system which are parallel to each other and fully electrical should be developed. While these said electrical integrated systems are developed, it is also required that they synchronize with each other and operate such that energy efficiency is provided to be maximum.

[0018] There are still conventional systems with mechanical propulsion system and diesel generator which are independent from each other in most of the ships. The advantageous sides of the system are low investment cost and that diesel internal combustion motors are known well by the ship operators. However, said inefficient and high emission operation modes form the main problem which should be solved. The aforementioned need for meeting the emission limits and decreasing operation costs has forced the ship designers and operators to new solutions. The advantage of the hybrid systems at the state of the art is that operators and managers decrease the fuel consumption, even if it is limited, without giving up conventional diesel systems. The fuel saving obtained helps the operators to stay below the emission limitations and in some situations, also creates a cost advantage when considered specifically to the ship. However, when restrictions which become stricter increasingly are considered, it is seen that the hybrid structures produce only short-term solutions. When the progress of the sector is considered, it is seen that the hybrid structures will give place to structures with 100% electrical and alternative energy sources in medium or long-term.

[0019] Because of the operation profile, most of the activities of tugs happen with partial loading, this means that propulsion and power systems in the ship are also loaded partially. Partial loading is a situation causing efficiency to decrease too much in the conventional systems. Whereas, it has been determined that this situation causes less efficiency loss in 100% electrical systems with batteries and converters. Although it has been determined as such, it is known that the efficiency of circuits of power electronics such as converters and drivers is between 20%-100% nominal power, very close to the nominal efficiency. A similar characteristic can be mentioned also for motors. However, when loading level drops to the levels of 5-10% in motors and power electronic equipment, a sudden decrease is observed in the efficiency rate. It is very important for competitiveness of 100% electrical tugs that high installed power operates with high efficiency also at partial loadings. In addition, in spite of the need for innovative solutions in the maritime sector, the ships with batteries and alternative energy sources are received with doubts by ship operators. The main questions these doubts which arise against new technologies cause to arise in ship operators and designers’ minds can be listed as follows: Thoughts about that problems will arise during ship construction and construction period will be extended, the system will not work with the performance mentioned or will never work, the thought about that it will be disadvantageous compared to the conventional systems when considering the investment cost and operational cost, the thought about that ship operators who are used to diesel systems will not be able to learn new systems or the fear about that ship operators who know these systems will not be able to be found, the fear of staying at sea because of running out of the battery in 100% electrical systems, battery -induced safety issues such as fire, toxic gas emission, the thought about that charging time will be very long. Beyond these concerns, the major problem preventing a 100% electrical tug from being put into practice is that the cost of the ship (investment + operational costs) is high. Another problem is to gain client’s confidence. These technical problems mentioned should be solved in order that a system which can respond to the concerns of the maritime sector arises. Besides, the efficiency should be prevented from decreasing even when the propulsion and power generation systems in 100% electrical tug systems are integrated.

[0020] Also, the batteries which will be used to switch fully electrical systems in ships should be able to give high power and energy without heating too much, should be long-life, should not require maintenance, should be in IP67 class and resistant to environmental factors, resistant to humid and salty weather conditions. Li-NMC (lithium nickel manganese cobalt oxide) batteries have high cell potential, high energy and power density, high cycle life, low internal resistance, relatively low cost, therefore, the chemistry of this battery is advantageous for ships.

[0021] When considering the existing technologies of energy storage and alternative energy sources, the most reasonable option for a ship with zero emission is lithium-ion energy storage systems. However, it has been observed that various problems occur again during integration them to the ships. Even if the sources of electric energy such as fuel cells, solar panels, wind turbines have a promising future, they are not the sources which can provide cost advantage compared to diesel in ships now. If a design of 100% electrical ship is realized, it will be required that R&D studies in which alternative energy sources such as solar, wind energy will also be used with batteries in the system are performed. When needed, the options of providing energy with battery, also when needed, providing energy with wind or solar panel should be provided and management of these energies should be planned well.

[0022] In addition, the battery type commonly used of Lithium-ion batteries in the maritime sector has been NMC (nickel manganese cobalt oxide). Because the chemistry of NMC battery provides a good balance between the parameters of safety, energy density, power density, cycle life and cost, it has become prominent in the maritime sector. Because investment cost of batteries and power electronic equipment they bring are much higher than the conventional diesel systems, correctly sizing of system components has critical importance in terms of competitiveness. Also, operating of the system at full efficiency is a desired situation and there is still a need for improvements for this. Especially in the battery sizing, an optimization between cost, energy capacity, instantaneous peak power capacity, battery life and charging time should be done. To decrease the investment costs, the total installed capacity (or the system providing electrical energy) should be as small as possible. However, it should be guaranteed that the ship will be able to complete its operations with zero emission without any problem and when needed, it will be able to reach the instantaneous peak power it needs for. One issue generally ignored in sizing is battery life. If the battery capacity is determined incorrectly, batteries may run out of their lifetime without being able to be operated enough for many years. It causes the return obtained from low operating costs not to amortize the investment costs, therefore, a noncompetitive structure to be formed. Daily number of cycles of batteries, depth of discharge (DoD), ambient temperature, average and peak C-rate values in the cycles are the factors which determine the battery lifetime and should be absolutely considered in sizing. When it is considered that the installed power in the system in ships will be at levels of megawatt-hours and system costs are considered, even the smallest mistake made in this optimization will affect the commercial success of the ship, therefore, of the product which is the project output substantially negatively. Although the factors determining the battery lifetime are certain, number of cycles, depth of discharge, ambient temperature, C-rate values which are expected to be used in calculations may be different in practice. Real conditions or the closest values can be reached with the records taken from a real ship. However, this practice is not very common in shipping and this type of information is generally classified as trade secret by firms. Besides, battery and DC / DC converter are not enough alone to minimize the investment costs and to provide 100% electrical systems with competitiveness. Here, the important main factor is the requirement of being high of general system efficiency. When the costs per kWh are considered, it is seen that electricity is more expensive than diesel. The price of electricity in Europe changes between 0.09 to 0.30 USD / kWh. When it is considered that the energy density of marine diesel is 11800 kWh / t and if it is assumed that the average fuel price is 600 USD / t, the cost for diesel is found as 0.05 USD / kWh. However, the efficiency of the conventional system operating with diesel is much lower than the efficiency of the proposed system with batteries. If a competitive structure is desired to be formed with the conventional system, it is obvious that the disadvantages high investment costs and the price of electricity create should be compensated with high system efficiencies.

[0023] In the patent document with the number of US9586665B2 at the state of the art, a process and a system for controlling a hybrid propulsion system for a marine vessel are mentioned. It is mentioned that said system comprises at least one internal combustion motor, at least one electric machine operating as a generator and motor, a propulsion unit with a propeller, a battery, and a motor.

[0024] In another patent document of US2012309242 (Al) at the state of the art, a hybrid ship propulsion system comprising at least one hybrid shaft generator driver is mentioned.

[0025] Therefore, the efficiency in current hybrid systems at the state of the art which are close to 100% electrical systems is still very low. To increase it, systems working with electrical energy should be developed. The most optimum working ranges, conditions should be determined with various algorithms, control units and systems which will run at least one relevant algorithm at most suitable conditions should be developed. In addition, battery sizing should be optimized by considering various parameters.

[0026] Summary of the Invention

[0027] The aim of the invention is to realize a zero-emission, fully electrical tug operating system which is used in harbour operations, and which comprises an integrated propulsion system and power generation system to maximize useful lifetime of batteries which provide energy efficiency and which are energy storage units and to store regenerative energy in said batteries and to be able to use it if necessary. With the invention, the problems of the conventional systems are removed and at the same time, a system which is efficient, competitive in terms of cost, has zero fuel consumption, zero emission is introduced.

[0028] Contrary to the conventional systems, the system comprising the integrated propulsion and power generation system which has been developed within the scope of the invention:

[0029] Is superior to the mechanically driven conventional systems in both technical and operational manners. Because the system is flexible and has the ability of adapting to various operation modes, the electric drive systems can be formed such that they will meet any kind of demand.

[0030] The most important property of the system is that it reduces the fuel consumption and the emission of greenhouse gases to zero. Because the system does not bum fuel and has almost no moving parts, the operational cost is low. Indirectly, because the system has almost no maintenance and repair needs, crew expenses decrease.

[0031] In spite of the gap between the installed power (or provided power) and average power consumption (or spent power), the system efficiency has been maximized because all equipment is operated as close to the ideal operation point as possible.

[0032] To sum up, the advantages of the system of the invention are:

[0033] To have zero fuel, zero emission,

[0034] To have 95% lower maintenance-repair costs than a similar ship operating with diesel,

[0035] To completing even the operations with the highest consumption with a single charge (2 hours of a nonstop operation),

[0036] - Recovery of regenerative energy special to the tugs operating in harbours (2%-6%), To have a long battery lifetime with 70% battery health (SoH) even after 10 years, To have a long operational time such as 12 hours in the modes having low power consumption such as oil cleaning,

[0037] There is a high operational efficiency from battery to propeller electric motor and from battery to 230 V AC consumer units.

[0038] Within the scope of the invention, a solution has been brought to inefficiencies of mechanical and hybrid propulsion systems with an alternative propulsion system. As seen from the Figure 3, with the propulsion system with the electric motor, the power needed by the propeller is provided from electric motors and batteries instead of internal combustion motors. The electrical propulsion system which is the subject-matter of the invention is very suitable especially for the ships with a variable operation profile such as tugs. Changing of the propeller load of a tug in which the system which is the subject-matter of the invention is used depending on the operation profile causes only minimal changes in the efficiency of electric propulsion system.

[0039] The ship in which the system which is the subject-matter of the invention is installed completes its operations with zero emission and without any problem and when necessary, it can reach the instantaneous peak power it needs in a very short time. Also, in the invention, the battery lifetime has been included to the system by being determined as correct as possible. Because daily number of cycles of batteries, depth of discharge (DoD), ambient temperature, average and peak C-rate values in the cycles are the factors which determine the battery lifetime, they have been included to the calculations in sizing.

[0040] Description of the Figures

[0041] Figure 1. It is a specific fuel oil consumption (SFOC) curve according to the loading rate for a ship type standard 4-stroke internal combustion motor.

[0042] Figure 2. It is a representative view of a hybrid system in which an energy storage unit is added to the conventional power system.

[0043] Figure 3. It is a representative general view of the system of the invention in which an energy storage unit is added to the conventional power system.

[0044] Figure 4. It is the power consumption graph of the system of the invention comprising the propulsion system and power system depending on time.

[0045] Figure 5. It is the block diagram of the energy control unit the system of the invention comprises.

[0046] Description of the References in the Figures

[0047] To be able to understand the invention better, meanings of the numbers in the figures are given below:

[0048] 1. System

[0049] 1.1. Propulsion system 1.1.1. Propeller

[0050] 1.1.2. Electric motor

[0051] 1.1.3. Driver

[0052] 1.2. Power generation system

[0053] 1.2.1. Energy storage unit

[0054] 1.2.1.1. DC / DC converter

[0055] 1.2.2. Filter

[0056] 1.3. Energy consumption unit

[0057] 1.3.1. Consumer unit

[0058] 1.3.2. Generator

[0059] 1.3.3. First transformer

[0060] 1.3.4. LCL filter

[0061] 1.3.5. Off-Grid converter

[0062] 1.3.6. Coast connection

[0063] 1.3.6.1. Second transformer

[0064] 1.4. Energy control unit

[0065] 1.4.1. Control unit

[0066] 1.4.2. Interface

[0067] 1.4.3. Communication unit

[0068] 1.5. DC Energy distribution element

[0069] 1.6. Hoisting engine

[0070] 1.6.1. Driver

[0071] ME. Main engine

[0072] DC Charge. DC Charge line

[0073] Detailed Description of the Invention

[0074] The invention is related to a zero-emission, fully electrical tug system (1) which provides energy efficiency, which is used in harbour operations, and which comprises an integrated propulsion system (1.1) and power generation system (1.2) to maximize useful lifetime of at least one energy storage unit (1.2.1) and to store regenerative energy in said energy storage units (1.2.1) and to be able to use it if necessary.

[0075] Therefore, to minimize load fluctuations on at least one main engine (ME) which gives the first movement to the drive shaft to provide energy efficiency and / or low fuel consumption and / or low emission and / or reducing maintenance costs in tugs which are multipurpose ships, the system (1) which is the subject-matter of the invention comprises at least one propulsion system (1.1) which comprises at least one propeller (1.1.1), at least one, preferably variable speed, bidirectional electric motor (1.1.2) which is an electric energy system having at least one operation mode and which can be used as a generator or motor according to the need and also, which can operate at least one propeller (1.1.1) at its most efficient points by using at least one energy storage unit (1.2.1), at least one driver (1.1.3) operating said electric motor (1.1.2); at least one power generation system (1.2) which comprises at least one energy storage unit (1.2.1) comprising at least one DC / DC converter which controls the voltage of a DC energy distribution element (1.5) and at least one LCL filter (1.2.2); at least one energy consumption unit (1.3) which comprises at least one consumer unit (1.3.1) or comprises at least one inverter for converting the power taken from itself into DC to rotate at least one said propeller (1.1.1) and also, at least one generator (1.3.2) for responding the concerns of managers and operators about running out of charge at sea, at least one first transformer (1.3.3), at least one LCL filter (1.3.4), at least one off- grid converter (1.3.5) which is operated in two modes as energy transmission control mode and grid control mode depending on the system operation, at least one coast connection (1.3.6) comprising at least one second transformer (1.3.6.1); at least one energy control unit (1.4) which comprises at least one control unit (1.4.1) controlling the system (1) to operate efficiently by running all technical components in sync, at least one human-machine interface (1.4.2), at least one communication unit (1.4.3) which provides effective operation by providing all system (1) components to communicate between each other; at least one DC energy distribution element (1.5); at least one hoisting engine (1.6) which comprises at least one driver (1.6.1).

[0076] In the preferred embodiment of the invention, there are two electric motors (1.1.2) which operate at least one propeller (1.1.1) and they are connected to each other in parallel.

[0077] In addition, said energy control unit (1.4) runs an optimization algorithm which manages at least one electric motor (1.1.2) depending on the power needed and / or said energy storage unit (1.2.1) and a DC energy distribution element (1.5) load sharing algorithm needed for not overloading of said DC / DC converters (1.2.1.1) and also, for synchronously aging of the energy storage units (1.2.1) and / or runs an inverse power recovery (regenerative energy storage) algorithm which provides the efficiency to increase by reusing the energy which emerges during the regenerative mode in which the regenerative energy which may be resulted from the propeller electric (or propulsion) motor (1.1.2) and / or at least one deck hoisting engine (1.6) is used and the escort mode which is the mode where the tug sails without working its own propellers (1.1.1) by being connected to the back of large ships with rope while it is piloting and / or after determining operator functions such as whether said DC energy distribution element (1.5) is charging / discharging, whether energy of at least one generator (1.3.2) will / will not be used, a DC energy distribution element (1.5) control and safety algorithm which has safety functions such as SoC (Security Operations Center) control, low and excessive voltage and which is for providing the DC energy distribution element (1.5) to share load between the energy storage units (1.2.1), keeping the DC voltage constant, safety functions of backup DC buses, providing protection selectivity during short circuit and / or provides voltage control of the DC energy distribution element (1.5) to prevent said DC energy distribution element (1.5) from falling below the limits or rising above the limits by keeping the voltage of said DC energy distribution element (1.5) in a certain range independently from the load amount and / or runs an energy control unit (1.4) and said energy control unit (1.4) algorithm for performing functions such as determining total power the system (1) needs for, working of at least one generator (1.3.2) or at least one auxiliary generator (1.3.4) in said system (1) with at least one off-grid converter (1.3.5) in coordination, coordinating the property of at least one AC coast connection charging and / or runs a DC fast charge / AC charge or charge from generator algorithm for performing functions such as confirming the connection with a land charging station to take place safe, SoC (State of Charge) control, introducing the limits of the charge source to the system (1) during charging and / or runs an energy storage unit analysis algorithm providing management of values such as DoD (Depth of Discharge), number of cycles, ambient temperature, C-rate (Charge-rate, charge and discharge rate of healthy energy storage unit) and calculation of the lifetime of the energy storage unit (1.2.1) in accordance with these values and / or for a DC energy distribution element (1.5) which provides benefitting from the speeds of flow manipulation of at least one DC / DC converter (1.2.1.1), at least one controlled IGBT and special type fuses, a hybrid protection unit (not shown in the figures and not numbered) with said IGBT and at least one fuse and / or runs a master-follower algorithm such that it will not form moment pulses in the system (1) for providing at least one electric motor (1.1.2) in the system (1) to operate with each other in coordination (in sync or in parallel). Also, the energy control unit (1.4) provides communication, control, detailed error mode analysis for power circuits (for preventing black-out of the ship) to be performed which are necessary not to lose the important ship functions in breakdowns.

[0078] The energy control unit (1.4) operates also said propulsion system (1.1), power generation system (1.2) and energy consumption unit (1.3) in coordination with each other (in sync).

[0079] Whole DC distribution element (1.5) mentioned in the invention is a bus.

[0080] The energy management algorithm (or method) which manages the energy storage units

[0081] (1.2.1), DC / DC converters (1.2.1.1), the electric motor (1.1.2) and drivers (1.1.3) depending on the power needed increases the general system efficiency without risking safety of the ship and by aging the energy storage units (1.2.1) simultaneously. The energy storage units

[0082] (1.2.1) in the DC network should perform load sharing in a stable way. For this, as mentioned above, the energy control unit (1.4) should run the relevant algorithms according to the need.

[0083] Details of the algorithms mentioned in the invention are given below:

[0084] Recovery of the regenerative energy algorithm: The recovery of the regenerative energy resulted from the propeller electric motor (1.1.2) (or propulsion motor) and deck hoisting engine (1.6) is aimed in the invention. The control algorithm providing maximum benefit in the recovery of the energy is an algorithm managing the values of reference torque, speed and power.

[0085] Besides, in a tug, there are two possible sources of the regenerative energy. One of them comes out in the stage of braking motor while unloading with the deck hoisting engine (1.6). The other results from electrical brake performed with the propeller electric motors (1.1.2). The motor driver (1.1.3) performs electrical brake by applying torque at the opposite direction of the rotating direction in such situations and transfers the energy back to the energy storage units (1.2.1). It is called as the escort mode that tugs sail without operating their own propellers (1.1.1) by being connected to the back of large ships with a rope while piloting. In the escort mode, the tug brakes in an emergency while being pulled from the back of the ship it pilots. The electrical energy which will come out during this brake is stored in the energy storage units (1.2.1). The algorithms about optimum usage of the regenerative energy have been developed in the scope of the invention. When a potential of the regenerative energy resulted from the ship operations forms, this is restored in the energy storage units (1.2.1). The physical and software system infrastructure has been designed such that it allows the potential of regenerative energy which may result from the propeller (1.1.1) and the hoisting engine (1.6) to be utilized.

[0086] The EMS (Energy Management System) algorithm which guarantees a high system efficiency: It is an algorithm which maximizes the lifetime and efficiency of the energy storage unit (1.2.1) and the efficiency of the electric motor (1.1.2). While increasing their load factor, the safety of the ship should not be risked. The equipment is operated at the maximum load as possible by leaving a margin which can meet instantaneous load fluctuations in the ship. Also, the desired lifetime is aimed by managing the values of the energy storage units (1.2.1) such as DoD, SoC, number of cycles, C-rate.

[0087] The algorithm for the harmony of two parallel propulsion electric motors (1.1.2): To increase the efficiencies of the propulsion electric motors (1.1.2), the total power the propeller (1.1.1) needs for is given with two parallel electric motors (1.1.2). These motors in the same mechanical system should work in a harmony with each other. If one motor is running and the other is started, it must start by rotating. The motors working in parallel have been provided to rotate in sync with each other with the master-follower (sequential operation) algorithm. Moment pulses should not be formed in the mechanical system during these transitions and parallel operating conditions. In addition, this type of properties which require fine adjustments will cause some technical problems in the field. To prevent this, this algorithm should be formed and controlled.

[0088] In the invention, 3 different charging ways have been determined in accordance with the demands of operators: a- There is a DC fast charge option which will be able to charge all capacity of the energy storage units (1.2.1) in a short time in the system (1). Because of the limited area in tugs, transformation of the AC network electricity to the DC is performed at the harbour not in the ship. Operating of tugs generally at the same harbour or close harbours makes installing one (or a few) charging station at the common use harbour advantageous instead of installing one charging station in each ship in each fleet. In the system (1), the fast-charging lines have the power capacity of 2x500kW=1000 kW. This means that the installed capacity of the ship can be charged within almost 1 hour. b- A slow charging option which can be connected in an easier manner physically with charging from the AC coast connection is presented to operators. When returned to the harbour from short operations which consume the capacity of the energy storage units (1.2.1) less, the AC charge which is easier to connect can be selected instead of the DC charge. Therefore, the DC fast-charging stations which there is limited number of at the harbour can be used by the other electrical ships at the fleet, if any. The AC charging feature can charge the ship within almost 10,5 hours. In the AC charge, the connector and cables at the ship’s side have been sized according to a predetermined value, for example 150 kVA. Besides, to respond to the concerns of the managers and operators about staying without charge at the sea, at least one generator (1.3.3) has been integrated to the AC energy distribution element (1.6), namely, to the 230V AC bus. The energy storage units (1.2.1) are deactivated via a mode the operator will select from the interface (1.4.2) on the screen, the relevant generator (1.3.3) is operated. The power taken from the generator (1.3.3) is used by being transformed to DC to rotate the propeller (1.1.1). That’s why, even if the energy storage units (1.2.1) will not be able to be used, the ship can return to the harbour with a low speed safely. c- The third charging option is charging with the diesel generator (1.3.3). It can be used in case that there is not any option of network connection at the harbour. It responds to the concern of end user about staying without any energy storage unit (1.2.1) again with the generators (1.3.3) included to the system. It is very fault-tolerant in terms of the fact that the system (1) comprises at least one auxiliary generator (1.3.4) or backup generator and its operating algorithm.

[0089] Therefore, 3 different charging options are included to the system (1) such that they respond to the end user. The invention is a system in which charging will be able to be made easily whatever the operation region and conditions of the ship are. With the Failure Mode and Effects Analysis (FMEA), all possible failure modes of the system (1) are determined, and their effects are analyzed. With the energy control unit (1.4) comprised by the system (1) which is the subject-matter of the invention, the ship does not stay completely without the energy storage unit (1.2.1) or the propulsion system (1.1) because of any failure mode arising. The DC network control and safety algorithm: It is an algorithm for providing load sharing between the energy storage units (1.2.1) in the DC network, keeping the DC voltage constant, safety functions of the backup buses, protection selectivity during a short circuit.

[0090] Another method for increasing the efficiency in the invention is to use a DC network instead of a conventional one. Because the primary energy source is DC, the main network’s being DC prevents losses firstly by decreasing the number of energy transformations. Another advantageous aspect of the DC bus is low transmission losses. There are not losses in the DC system resulting from the reactance and skin effect in the AC system. In addition, Joule losses in the DC system with 2 conductors will be at a lower level than ones in the AC system with 3 conductors. The main reason for not using DC network in the current hybrid structures more frequently is difficulties in the short circuit and overcurrent protection. As known, cutting the DC current and absorbing the arc formed is much more difficult than the AC current. To prevent this problem, in small sized tugs, instead of using big and heavy DC switches compared to its AC equivalents, protection is realized with at least one IGBT (Insulated-Gate Bipolar Transistor) and at least one fuse in the invention. Therefore, a hybrid protection strategy has been adopted by using fast-blowing special sensitive fuses and the current control ability of semi-conductors based on nanoseconds. The DC switch used in the invention is only for the “bus-tie breaker” between buses with backup. Also, in the invention, the effects of EMI and EMC may arise. Said effects cause damages in signal cables close to the events of EMI and “common-mode effect” generated by the IGBT switching elements. That’s why, attentive engineering in the issues of equipment suitable for EMC, design, layout, cable connections etc. has been realized with R&D activities.

[0091] In the system (1) which is the subject-matter of the invention, the energy storage unit (1.2.1) is preferably a Li-NMC (lithium nickel manganese cobalt oxide) battery. Depth of discharge (DoD), ambient temperature, average and peak C-rate values in cycles, daily number of cycles of the energy storage units (1.2.1) are the factors which determine their lifetimes and should be absolutely considered in sizing. Input values have been obtained by receiving support from simulation tools for this type of values (number of cycles, depth of discharge, ambient temperature, C-rate values which are expected to be used in calculations) in the invention. Because electric networks of ships are separate and isolated systems, each one of them can be evaluated as a micro-network. These micro-networks which is presented in the project and which the lithium-ion batteries of the main energy source form tend to become common in accordance with the future goals of the maritime authorities. The micro-networks which have an increasing importance in the land network form an information infrastructure about technologies and techniques such as forming AC networks with power electronics, DC networks, energy management systems, integration of the users comprising DC sources to the network.

[0092] The main advantage and the main factor of the system (1) which is the subject-matter of the invention providing it to be competitive about the cost compared to the conventional system is that the general system efficiency is high. The system (1) which is the subject-matter of the invention has an integrated structure. Namely, two systems which are the DC power generation system (1.2) and the electric propulsion system (1.1) are brought together as integrated. Therefore, the whole structure gets out of one hand and the system efficiency having a critical importance can be optimized better. Also, possible incompatibility problems between the propulsion systems (1.1) and the power generation systems (1.2) have been prevented. Thanks to this, problems occurring in the ship construction process are decreased, therefore, construction time and costs are reduced. This integrated system has been brought together as in little number of panels, namely energy control units (1.4) as possible. Due to this central panel system, the most important systems of the ship are in the same area. Therefore, the ship operators can perform failure monitoring easily. In addition, the number of temperature and humidity controlled environment the power electronic systems need for has been decreased. HVAC (Heating, ventilation and air conditioning) costs have been decreased by air-conditioning only the environment in which the panel exists in the ship.

[0093] The system (1) which is the subject-matter of the invention can be scaled for tugs having different installed powers and propeller powers. The centralized physical structure provides necessary changes to be done easily when the sizes of the system are changed. The power generation system (1.2) is provided to operate in a stable, fast and efficient manner with the high performing energy control unit (1.4) (or energy management system). With the propeller propulsion system (1.1) the system which is the subject-matter of the invention comprises, a safe structure which has a high ability of dynamic response and maneuver, which is efficient, which has an ability of regenerative energy recovery has been formed. The energy storage and energy transformation system, motor drivers, electric motors in the project require almost no maintenance and repair. Compared to diesel internal combustion machine systems, the costs of maintenance and repair have been decreased at least 95%. That’s why, the operational costs of the ship (OPEX) have been decreased more and commercial competitiveness has been provided.

[0094] In the Figure 3, a representative view of the system (1) which is the subject-matter of the invention in which at least one power generation system (1.2) comprising at least one energy storage unit (1.2.1) is added to the conventional power generation system is given.

[0095] The optimum operation of the system (1) which is the subject-matter of the invention is that it runs the algorithms defined to the energy control unit (1.4) the system (1) comprises by considering the current condition of the tug such that it provides energy efficiency, low fuel consumption and therefore, low emission.

[0096] In the invention, a detailed energy storage unit (1.2.1) sizing has been performed with operation profile analysis and lifetime calculation of the energy storage unit (1.2.1) considering many factors. Therefore, an advantageous system compared to conventional and current hybrid systems, which has a high price competitiveness has been formed. Via the DC / DC converter (1.2.1.1), the current voltage, charge state of the energy storage unit (1.2.1) can be controlled and due to the EMS algorithms, the optimum operation conditions of the energy storage units (1.2.1) are provided. The energy storage units (1.2.1) have almost 2 hours of uninterrupted working time in intensive operations, almost 12 hours of uninterrupted working time in the operations with low power consumption. By preferring the DC network, also alternative energy sources such as photovoltaic panels and hydrogen fuel cells are included to the system (1). Without changing the main system structure, by connecting other energy sources mentioned to the system (1) instead of the energy storage units (1.2.1) the system (1) comprises, switching between the energy sources can be made. Therefore, the energy storage unit (1.2.1) can be at least one solar panel (or photovoltaic panel) and / or at least one wind turbine and / or at least one hydrogen fuel cell according to the embodiments of the invention.

[0097] Besides, the protection problem in the DC network has been solved with the hybrid protection. Namely, by decreasing the number of DC switches in the system, a gain from cost, place and weight has been provided. In the invention, if a network structure in which only an AC network and AC / DC / AC motor drivers are used instead of DC network was selected, there would be totally 16 energy transformation between AC -DC and totally 16 power electronics converters. With the DC bus solution, the total number of AC -DC transformations has been reduced to 8, the number of DC / DC converters (1.2.1.1) which is the power electronics converter has been reduced to 12. That’s why, besides efficiency, a gain is provided also from the investment cost, weight and place.

[0098] For the ship to operate safely, reliably and efficiently, all processes of control / calculation / activation / deactivation which should be done by at least one energy control unit (1.4) are performed according to the need according to the method steps with at least one step below regardless of the order:

[0099] - For the electric network of the ship, performing calculations of short circuit and harmonic voltage distortion

[0100] Introducing the single line diagram in which the energy producers and the energy consumers are shown and the main properties of the electric producers and consumers to an algorithm through an interface (1.4.2)

[0101] - Defining a magnitude value of short circuit current at a predetermined value for preferably a 750V DC energy distribution element (1.5) and a 230V AC energy distribution element (1.6)

[0102] Activating / deactivating the necessary propeller propulsion electric motor (1.1.2) for the system (1) and the drivers (1.1.3) compatible with this by selecting them through the interface (1.4.2)

[0103] Selecting the sizes of at least one motor and driver through the interface (1.4.2) such that it maximizes the efficiency in various operations of the ship and if necessary, activating / deactivating the relevant motor and driver

[0104] Selecting the nominal voltage of the propeller propulsion electric motor (1.1.2) and the voltage of the DC energy distribution element (1.5) through said interface (1.4.2) Selecting an off-grid converter (1.3.5) current through said interface (1.4.2) based on at least one consumer unit (1.3.1), the power of the diesel generator (1.3.3) or at least one auxiliary generator (1.3.4) and power of an AC coast connection

[0105] Operating at least one 3 phase IGBT bridge rectifier (active front-end) driver to prevent the harmonic distortion in the 230V AC network

[0106] - Providing separation of the network and at least one DC / DC converter (1.2.1.1) with galvanic isolation against the electromagnetic interference and noise which may form in cables and electrical equipment in the ship network and around the integrated converter panel due to the power electronics equipment - Using at least one liquid / air cooling system by determining a suitable cooling and cooling temperature and other cooling parameters according to it and therefore, cooling at least one DC / DC converter (1.2.1.1), at least one propeller propulsion electric motor (1.1.2) and at least one driver (1.1.3)

[0107] Operating the electric producers and consumers of the ship in coordination for energy management in accordance with the load flow diagram

[0108] - Keeping the voltage of the DC energy distribution element (1.5) under control, providing aging of at least one energy storage unit (1.2.1) simultaneously with load sharing between it and the energy storage unit (1.2.1) and therefore, increasing the efficiency of the energy storage unit (1.2.1)

[0109] Transferring the regenerative energy to the DC energy distribution element (1.5) with at least one IGBT bridge and providing reusage of this energy later by charging the energy storage units (1.2.1)

[0110] - During an escort mode which is the mode of a tug’s accompanying a ship, storing the maximum regenerative energy which is obtained from a possible brake and which the electric motor (1.1.2) the propulsion system (1.1) comprises produces after braking in at least one energy storage unit (1.2.1) and providing synchronization between them

[0111] Activating / deactivating at least one charging mode of at least one energy storage unit (1.2.1), for example, DC fast charging or slow AC charging mode, charging mode with at least one generator (1.3.2) according to the need

[0112] - Providing at least one off-grid converter (1.3.5) to work in coordination with at least one generator (1.3.2) and synchronization of said off-grid converter (1.3.5) with at least one generator (1.3.3)

[0113] - Running various algorithms for control of the DC network voltage, consumer and energy source coordination, power quality management and maximizing the efficiency

[0114] Controlling the voltage amplitude, frequency, wave shape, power quality and harmonic effects in the AC bus directly

[0115] In the step electromagnetic interference and noise which may form in cables and electrical equipment in the ship network and around the integrated converter panel due to the power electronics equipment” , after at least one off-grid converter (1.3.5), at least one first transformer (1.3.3) which is suitable for using for isolation, which has electrostatic shielding, suitable uk value is used. In addition, the physical properties, montage, and the electric lines inside of the integrated panel have been made in accordance with standards against the EMC (electromagnetic compatibility) problems again. It is such that cables have shielding, cover gaskets are EMC type, different voltage levels are at separate physical locations.

[0116] Total loss of an integrated panel is approximately 1300 kW. A loss power of this magnitude affects the ambient temperature and drivers’ operation negatively. The cooling technique (air / water) of the off-grid converters (1.3.5) has been determined with the cost, sizing, and loss power analysis.

[0117] The energy storage units (1.2.1) are prevented from overloading and the DC energy distribution element (1.5) (or DC bus) is prevented from breaking down by operating the electric producers and consumers in coordination by the energy control unit (1.4). Also, the energy control unit (1.4) decides when the energy storage units (1.2.1) which are electric generators will work.

[0118] Except of communication of the integrated power generation system (1.2) and propulsion system (1.1) between themselves, communications between other important systems in the ship occur and at least parameter has been determined through at least one interface (1.4.2) for this. With said interface (1.4.2), diagnostic (failure detection), alarm, monitoring and controlling functions are performed.

[0119] Except of using the energy storage units (1.2.1), connection to the mains is also made during charging. The consumers having electricity need at the voltage level of 230 VAC are brought together in a 230V AC bus in the ship. The energy need of this bus is provided with at least one off-grid converter (1.3.5). All these functions mentioned are performed with the infrastructure of bidirectional communication lines and power electronics converters.

[0120] To sum up, if and only if physical placement / making connection of the system (1) which is the subject-matter of the invention is as in the schema given in the Figure-3, the electrical efficiency reaches the maximum. Connection with each other and / or placement of each technical unit in the schema have been decided as a result of many R&D studies. Increasing efficiency has been seen only in such a way. An example embodiment of the invention:

[0121] The huge difference between the installed power of tugs and average power they consume during their activity poses a problem in terms of efficiency. Because the ship should move weights which are hundreds of times its own weight as tonnage at the moments of pushing / pulling, installed power of tugs is very high compared to their sizes. However, this peak loading moment occurs in a very short period of time of the operation profile. Tugs use more than 85% of their installed power only in a few minutes, moreover, sometimes in a shorter time in a day. In other operations such as patrol, fire / leakage responding, movement with full speed, 5-50% of the installed power is used. In the Figure-4, this situation is seen in detail.

[0122] In an example embodiment of the invention (Figure 4), the ship pushing / pulling operation profile for a harbour type tug is given. In the scope of feasibility studies, other operation profiles have also been analyzed. However, this example embodiment is shared because the upper limit is the pushing / pulling operation in terms of instantaneous power consumption. The detailed operation description is as follows: Between 0-10th minutes: Waiting

[0123] Between 10-40th minutes: Moving to the activity region at the distance of 4 sea miles from the harbour with the speed of 8 knot

[0124] Between 40-45th minutes: Rope maneuvers

[0125] Between 45-85th minutes: Pulling the ship with the speed of 6 knot through 4 sea miles

[0126] Between 85-90th minutes: Waiting

[0127] Between 90- 100th minutes: Docking the ship

[0128] Between 100- 105th minutes: Waiting

[0129] Between 105-113th minutes: Returning to the harbour with the speed of 6 knot

[0130] Between 113-118th minutes: Waiting

[0131] As seen, even in the operation having the highest power consumption, the time in which all the installed propeller (1.1.1) power is used is 10 minutes. In the operation except of this period and waiting periods, the average power consumption is 354 kW. During whole operation, when the waiting periods are excluded, the load factor of the propeller propulsion system (1.1) is found as 21,3%. 90% of the total power consumption in the ship is made by the propulsion system (1.1). Therefore, this low load factor of the propulsion system (1.1) is almost the same as the capacity factor of the energy storage units (1.2.1) the power generation system (1.2) (in the electric production system of the tug) comprises. Both the electric motor (1.1.2) and drivers (1.1.3) in the propulsion system (1.1), and the energy storage units (1.2.1) and DC / DC converters (1.2.1.1) in the power generation system (1.2) operate generally at low loading.

[0132] Because the power consumption of the propulsion system (1.1) is 90% of the total power consumption of the tug, the partial loading problem explained for the propulsion system (1.1) affects the DC / DC converters (1.2.1.1) in the same way. In an example embodiment of the invention, let the total power consumption be 300 kW in the system (1) in which there are 4x1500kW DC / DC converters (1.2.1.1) connected to 4 different battery groups. If all DC / DC converters (1.2.1.1) are active continuously and equal load sharing is made with droop control, the load on each DC / DC converter (1.2.1.1) becomes 75 kW. This means that DC / DC converters (1.2.1.1) bear 5% load. If only 1 DC / DC converter (1.2.1.1) met all load of the ship, total loading would be 20%. This means an efficiency gain up to 30%. This situation has an effect decreasing the general system efficiency. Cost competitiveness which is the most important factor of the commercial success of the invention is directly related to the total system efficiency. The inputs of the system (1) efficiency analysis are in the table below. In the Table-1, the efficiency table of the system (1) at partial loading for a zeroemission tug is given. The efficiency values related to the propulsion electric motor (1.1.2) and its driver (1.1.3) in the Table-1 are for the case in which a single motor drives the 1450 kW propeller (1.1.1). Whether the total power of the tug is divided to the motors equally (50%-50%) or asymmetrically is decided according to the operation profiles. The prices, sizes of the drivers and motors and obtained gain of efficiency determine the sizes of the system as a result of a benefit-cost analysis.

[0133] Table-1: The efficiency table of the system (1) at partial loading for a zero-emission tug

[0134] In the invention, an efficient physical infrastructure and software power management system have been developed with the invention for a tug using low power in most of the operation time. If a single electric motor (1.1.2) and driver (1.1.3) are used for a propeller (1.1.1) having the total mechanical power need of 1450 kW, the long-term average efficiency of the propulsion system (1.1) will remain at low levels. To prevent this problem, the solution proposed in the invention is to use two electric motors (1.1.2) and driver (1.1.3) which have 1450 kW total power in a propeller (1.1.1). That’s why, only one electric motor (1.1.2) will drive the propeller (1.1.1) at low loadings. As loading increases, a second electric motor

[0135] (1.2.1) will be paralleled to the mechanical system already rotating with the flying start method while rotating. The electric motors (1.2.1) working in parallel will be able to transmit their total power which is totally 1450 kW to the propeller through a gear box by working at the same speed with a “master-follower” algorithm, if necessary. That’s why, the load factor of motors and drivers will have been increased. Therefore, the propeller (1.1.1) and the control unit (1.4.1) comprised by the energy control unit (1.4) the propulsion system (1) which is the subject-matter of the invention comprises are driven with an electric motor

[0136] (1.1.2), when loading increases while said propeller (1.1.1) works, the second electric motor

[0137] (1.1.2) and the first electric motor (1.1.2) are operated in parallel to each other.

[0138] 90% of the total power consumption in the ship is made by the propulsion system (1.1). Therefore, the power consumption of the propulsion system (1.1) and the capacity factor in the power generation system (1.2) are almost the same. Both the electric motor (1.1.2) and its drivers (1.1.3) in the propulsion system (1.1), and the energy storage units (1.2.1) and DC / DC converters (1.2.1.1) in the power generation system (1.2) operate generally at low loading. In the analysis performed, the prevented emission amounts as a result of 2 hours operations of a 100% electrical ship can be seen in the Table-2. In the comparison made, a similar conventional ship having the same size has been used as a base. MDO (marine diesel oil) has been assumed as the fuel. Namely, in case that the ship is a 100% electrical ship, the prevented amounts of gas emission are very high.

[0139] Table-2: Prevented gas emission amounts in kilograms for 2 hours operation of a zeroemission tug

[0140] Industrial Applicability of the Invention

[0141] The invention is related to a zero-emission, fully electrical tug system which is used in harbour operations, and which comprises an integrated propulsion system (1.1) and power generation system (1.2), to maximize useful lifetime of batteries and to store regenerative energy in said batteries and to be able to use it, if necessary, which provides energy efficiency, and it is industrial applicable.

[0142] The invention is not limited to the descriptions above, a skilled person in the art can perform different embodiments of the invention easily. These should be interpreted within the protection scope of the invention claimed with the claims.

Claims

CLAIMS1. For minimizing load fluctuations on at least one main engine (ME) which gives the first movement to the drive shaft to provide energy efficiency and / or low fuel consumption and / or low emission and / or reducing maintenance costs in tugs which are multipurpose ships, a system (1) comprising at least one propulsion system (1.1) which comprises at least one propeller (1.1.1), at least one, preferably variable speed, bidirectional electric motor (1.1.2) which is an electric energy system having at least one operation mode and which can be used as a generator or motor according to the need and also, which can operate at least one propeller (1.1.1) at its most efficient points by using at least one energy storage unit (1.2.1), at least one driver (1.1.3) operating said electric motor (1.1.2); at least one power generation system (1.2) which comprises at least one energy storage unit (1.2.1) comprising at least one DC / DC converter which controls the voltage of a DC energy distribution element (1.5) and at least one LCL filter (1.2.2); at least one energy consumption unit (1.3) which comprises at least one consumer unit (1.3.1) or comprises at least one inverter for converting the power taken from itself into DC to rotate at least one said propeller (1.1.1) and also, at least one generator (1.3.2) for responding the concerns of managers and operators about running out of charge at sea, at least one first transformer (1.3.3), at least one LCL filter (1.3.4), at least one off-grid converter (1.3.5) which is operated in two modes as energy transmission control mode and grid control mode depending on the system operation, at least one coast connection (1.3.6) comprising at least one second transformer (1.3.6.1); at least one energy control unit (1.4) which comprises at least one control unit (1.4.1) controlling the system (1) to operate efficiently by running all technical components in sync, at least one human-machine interface (1.4.2), at least one communication unit (1.4.3) which provides effective operation by providing all system (1) components to communicate between each other; at least one DC energy distribution element (1.5); at least one hoisting engine (1.6) which comprises at least one driver (1.6.1); characterized by comprising said energy control unit (1.4) which runs an optimization algorithm which manages at least one electric motor (1.1.2) depending on the power needed and / or said energy storage unit (1.2.1) and a DC energy distribution element (1.5) load sharing algorithm needed for not overloading of said DC / DC converters (1.2.1.1) and also, for synchronously aging of the energy storage units (1.2.1) and / or runs an inverse power recovery (regenerative energy storage) algorithm which provides the efficiency to increase by reusing the energy which emerges during the regenerative mode in which the regenerative energy which may be resulted from the propeller electric (orpropulsion) motor (1.1.2) and / or at least one deck hoisting engine (1.6) is used and the escort mode which is the mode where the tug sails without working its own propellers (1.1.1) by being connected to the back of large ships with rope while it is piloting and / or after determining operator functions such as whether said DC energy distribution element (1.5) is charging / discharging, whether energy of at least one generator (1.3.2) will / will not be used, a DC energy distribution element (1.5) control and safety algorithm which has safety functions such as SoC control, low and excessive voltage and which is for providing the DC energy distribution element (1.5) to share load between the energy storage units (1.2.1), keeping the DC voltage constant, safety functions of at least one backup DC bus, providing protection selectivity during short circuit and / or provides voltage control of the DC energy distribution element (1.5) to prevent said DC energy distribution element (1.5) from falling below the limits or rising above the limits by keeping the voltage of said DC energy distribution element (1.5) in a certain range independently from the load amount and / or runs an energy control unit (1.4) and said energy control unit (1.4) algorithm for performing functions such as determining total power the system (1) needs for, working of at least one generator (1.3.2) in said system (1) with at least one off-grid converter (1.3.5) in coordination, coordinating the charging property of at least one AC coast connection and / or runs a DC fast charge / AC charge or charge from generator algorithm for performing functions such as confirming the connection with a land charging station to take place safe, SoC control, introducing the limits of the charge source to the system (1) during charging and / or runs an energy storage unit (1.2.1) analysis algorithm providing management of values such as DoD, number of cycles, ambient temperature, C-rate and calculation of the lifetime of the energy storage unit (1.2.1) in accordance with these values and / or for a DC energy distribution element (1.5) which provides benefitting from the speeds of flow manipulation of at least one DC / DC converter (1.2.1.1), at least one controlled IGBT, a hybrid protection unit (not shown in the figures and not numbered) with said IGBTs and at least one fuse and / or runs a master-follower algorithm such that it will not form moment pulses in the system (1) for providing at least one electric motor (1.1.2) in the system (1) to operate with each other in coordination (in sync or in parallel).

2. A system (1) according to claim 1, characterized by comprising two electric motors (1.1.2) which run at least one propeller (1.1.1) and which are connected to each other in parallel.

3. A system (1) according to claim 2, characterized by comprising the energy storage unit (1.2.1) which is a Li-NMC (lithium nickel manganese cobalt oxide) battery.

4. A system (1) according to claim 3, characterized by comprising the energy storage unit (1.2.1) which can be at least one solar panel (or photovoltaic panel) and / or at least one wind turbine and / or at least one hydrogen fuel cell.

5. For the ship to operate safely, reliably and efficiently, to perform all processes of control / calculation / activation / deactivation which should be done by at least one energy control unit (1.4) according to the need regardless of the order; a method characterized by the steps below:- For the electric network of the ship, performing calculations of short circuit and harmonic voltage distortionIntroducing the single line diagram in which the energy producers and the energy consumers are shown and the main properties of the electric producers and consumers to an algorithm through an interface (1.4.2)- Defining a magnitude value of short circuit current at a predetermined value for preferably a 750V DC energy distribution element (1.5) and a 230V AC energy distribution element (1.6)- For said AC energy distribution element (1.6), calculating a voltage distortion value at the same timeActivating / deactivating the necessary propeller propulsion electric motor (1.1.2) for the system (1) and the drivers (1.1.3) compatible with this by selecting them through the interface (1.4.2)Selecting the sizes of at least one motor and driver through the interface (1.4.2) such that it maximizes the efficiency in various operations of the ship and if necessary, activating / deactivating the relevant motor and driverSelecting the nominal voltage of the propeller propulsion electric motor (1.1.2) and the voltage of the DC energy distribution element (1.5) through said interface (1.4.2) Selecting an off-grid converter (1.3.5) current through said interface (1.4.2) based on at least one consumer unit (1.3.1), the power of the diesel generator (1.3.3) and power of an AC coast connectionOperating at least one 3 phase IGBT bridge rectifier (active front-end) driver to prevent the harmonic distortion in the 230V AC network- Providing separation of the network and at least one DC / DC converter (1.2.1.1) with galvanic isolation against the electromagnetic interference and noise which may form in cables and electrical equipment in the ship network and around the integrated converter panel due to the power electronics equipment- Using at least one liquid / air cooling system by determining a suitable cooling and cooling temperature and other cooling parameters according to it and therefore, cooling at least one DC / DC converter (1.2.1.1), at least one propeller propulsion electric motor (1.1.2) and at least one driver (1.1.3)Operating the electric producers and consumers of the ship in coordination for energy management in accordance with the load flow diagram- Keeping the voltage of the DC energy distribution element (1.5) under control, providing aging of at least one energy storage unit (1.2.1) simultaneously with load sharing between it and the energy storage unit (1.2.1) and therefore, increasing the efficiency of the energy storage unit (1.2.1)Transferring the regenerative energy to the DC energy distribution element (1.5) with at least one IGBT bridge and providing reusage of this energy later by charging the energy storage units (1.2.1)- During an escort mode which is the mode of a tug’s accompanying a ship, storing the maximum regenerative energy which is obtained from a possible brake and which the electric motor (1.1.2) the propulsion system (1.1) comprises produces after braking in at least one energy storage unit (1.2.1) and providing synchronization between themActivating / deactivating at least one charging mode of at least one energy storage unit (1.2.1), for example, DC fast charging or slow AC charging mode, charging mode with at least one generator (1.3.2) according to the need- Providing at least one off-grid converter (1.3.5) to work in coordination with at least one generator (1.3.2) and synchronization of said off-grid converter (1.3.5) with at least one generator (1.3.2)- Running various algorithms for control of the DC network voltage, consumer and energy source coordination, power quality management and maximizing the efficiencyControlling the voltage amplitude, frequency, wave shape, power quality and harmonic effects in the AC bus directly.

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