Abstract

The objective of this paper is to design organic Rankine cycle units that are cooled by air or seawater and show"br" the changes in net power output and power requirement as the ambient air temperatures change both geographically"br" and seasonally. The organic Rankine cycle unit uses the available waste heat from the scavenge air system for a"br" 4,100 TEU container ship. This work uses a two-step single objective optimisation capable of selecting 14 design"br" characteristics of the organic Rankine cycle unit and with the aim of minimising the vessel’s CO2 emissions. The"br" work contributes to the study of off-design operation and different cooling fluids for marine waste heat recovery"br" systems. The results show that the organic Rankine cycle unit is more adaptable to ambient air temperatures when"br" using seawater as a cooling fluid while air is an attractive option for extremely low ambient temperatures. Document type: Conference object

Abstract

The aim of this study is to assess whether the value of flexibility can influence the investment decision between CO"inf"2"/inf" ship and pipeline transport and, therefore, the way the infrastructure develops. For this, the value of a carbon capture and storage project are calculated with the standard net present value (NPV) and with the least-squares Monte Carlo method, which is a real option approach (ROA).Results of the NPV and ROA show that ships are preferred for small volumes over large distances. For instance, for a design capacity of 2.5Mt/y, pipelines are preferred for 250km and ships for 500km. The ROA shows that the option value to abandon the project and to switch off the CO"inf"2"/inf" capture unit temporarily are about 2-4 and 5 times as high for the ship compared to the pipeline configurations, respectively. The option to connect to another storage reservoir has a value of "1000M€ for the 10MtCO"inf"2"/inf"/y configurations. Consequently, this option turns the project values positive for the 10MtCO"inf"2"/inf"/y pipeline and shipping configurations over a distance of 250 and 500km.Overall, the value of flexibility did not change the preferred transportation mode from pipeline to ship transport, at least for the considered options to abandon the project, switch off the capture unit temporarily and switch to another storage reservoir. However, under the assumptions made, all 10MtCO"inf"2"/inf"/y cases were not profitable with the NPV approach, while they were profitable with the ROA.

Abstract

"jats:p" Synchronous motors and their modifications (ac converter-fed motor, etc.) enable to develop low-noise, reliable and economically efficient electric drive systems. The construction of up-to-date systems based on the synchronous machines is impossible without development of the computing software incorporating mathematical and computing simulation. In its turn, modelling of the synchronous machines as a rule is based on the equations by Park-Gorev, application of which requires adoption of a series of allowances. These allowances in a number of cases do not permit to obtain adequate results of the simulation coinciding with the results of field experiments of the systems under review. Moreover, while applying the system of equations by Park-Gorev to research the systems including interaction of synchronous machines with semiconducting converters of electric energy it is necessary simulate the process of formation their controlling signals in the sphere of frequency. If the states of converter’s keys are defined not only by controlling impulses but also by the state of currents in the synchronous machines flowing through them, such approach is not reasonable. Document type: Article

Abstract

One of the most essential tasks for a number of systems of the automatic controls in the autonomous electric power systems of the water transport is accurate calculation of variable harmonic components in the non-sinusoidal signal. In the autonomous electric power systems operating with full semiconductor capacity, the forms of line currents and voltages are greatly distorted, and generator devices generate voltage with inconsistent frequency, phase and amplitude. It makes calculation of harmonic composition of the distorted signals be a non-trivial task. The present paper provides a mathematical set for solution of the outlined problem including the realization in the discrete form. The simplicity and efficiency of the system proposed make possible to perform its practical realization with the help of cheap FPGA. The test of the developed system has been performed in the medium Matlab. The modern ship's electric power systems (SEPS) are characterized by the presence in its composition of a great number of the conversion load, including frequency transformer, un-interruptive power supply, inverters, rectifiers and other consuming devices varying in their non-linear volt-ampere features. Similar load has a negative impact on the supplying network of the alternating current, generating into it highest harmonic components of currents and voltages. At the same time, a great deal of the ship's automation systems apply the line currents and voltages to form the reference signal. Thus, for example, an automatic voltage regulator (AVR) of the ship's synchronous generators (SG) performs regulation by an average value of voltages and currents in the circuit. However, with the distorted form of the variable signals (that is caused by the presence of a wide range of highest harmonics) their average value increases and an automatic voltage regulator (AVR), correcting the error, decreases the exciting current of the synchronous generator that results in loss of voltage in the ship's electric power systems (SEPS). Consequently, decrease in relative value and increase in highest harmonics take place, and, thus, the electromagnetic moment of the non-synchronous motors decreases, the level of interferences influencing the systems of the ship's automatic controls becomes higher, and the losses in the power supply lines enlarge. Practically, such an error is corrected by the adjustment of the voltage corrector (VC). However, as the harmonic composition periodically varies depending on the mode of operation and the composition of the load of the electric power station, the setting of the voltage corrector should be changed constantly. This problem should be solved by measuring the level of the basic harmonics of the current and voltages of the ship's circuit. On the other side, it is known that filter-compensating devices (FCD) are the most efficient means to increase the quality of electric energy in the ship's power supply systems at the moment. Their efficiency in higher harmonic suppression and compensation of their volt-ampere reactive may be provided only by the high accuracy of the calculation of parameters in the target harmonics of the line currents and voltages. 2. Settlement of the problem Thus, the required functional set of the systems taken as an example determining their efficiency, in particular, and their operational performance in general, is a set for identification of external parameters of the control system. The major function of the block is extraction of harmonic components required for their analysis, calculation of their parameters from the distorted signal and application of the results of that analysis in the control of the means of the increasing values for quality of the electric Document type: Article