Impact of marine power system architectures on IFEP vessel availability and survivability

In recent years integrated full electric propulsion (IFEP) has become a popular power system concept within the marine community, both for the naval and the commercial community. In this paper the authors discuss the need for a detailed investigation into the impact of different IFEP power system architectures on the availability of power and hence on the survivability of the vessel. The power system architectures considered here could relate to either a commercial or a naval vessel and include radial, ring and hybrid AC/DC arrangements. Comparative fault studies of the architectures were carried out in an attempt to make valuable observations on the survivability of a vessel. Simulation results demonstrate that the ring and hybrid AC/DC architectural contribute to a higher survivability than the radial architecture. However, there are still challenges that need to be addressed and therefore potential solutions such as fault current limiters will be considered

Database management for high resolution condition monitoring of wind turbines

Wind turbine condition monitoring (CM) is an area of research which has been receiving a large amount of attention in the recent years. This has been influenced mainly by the recent uptake of wind farms being installed around the country. Operational and maintenance expertise in the area of wind turbine CM is therefore seen to be of growing importance but is yet to be well established in the industry due to its unverified economic benefits. The majority of the research which can be found in the literature has been based on simulation or test rig data, often due to the lack of availability of extensive historical data sets containing 'interesting' events, as well as the difficulties associated in gaining access to such data, due to its commercially sensitive nature. It can not be readily claimed, nor shown that laboratory based testing or simulations actually reflect real turbine operation, due to scaling, control and dynamic considerations. In order that different patterns of machine deterioration can be determined and detected in their incipient stages, precise high resolution data, of existing monitored parameters, should be sampled at frequencies higher than that is typically available in the integrated SCADA systems installed in most modern turbines today. This paper reports the design of a data acquisition platform which will be mounted on a 660 kW VESTAS V47 wind turbine. Details of the monitoring equipment used, the installation requirements as well as the system architecture will be presented and discussed

Implications of fault current limitation for electrical distribution networks

This paper explores the potential future need for fault current limitation in the UK's power system, and some of the technical implications of this change. It is estimated that approximately 300-400 distribution substations will require fault current limitation, based on the statistical analysis of the projected fault level "headroom" (or violation). The analysis uses a UK electrical system scenario that satisfies the Government's target for an 80% cut in CO2 emissions by 2050. A case study involving the connection of distributed generation (DG) via a superconducting fault current limiter (SFCL) is used to illustrate the potential protection and control issues. In particular, DG fault ride-through, autoreclosure schemes, and transformer inrush current can be problematic for SFCLs that require a recovery period. The potential solutions to these issues are discussed, such as the use of islanding or automation to reduce the fault level

Single shot, temporally and spatially resolved measurements of fast electron dynamics using a chirped optical probe

A new approach to rear surface optical probing is presented that permits multiple, time-resolved 2D measurements to be made during a single, ultra-intense ( > 1018 W cm−2) laser-plasma interaction. The diagnostic is capable of resolving rapid changes in target reflectivity which can be used to infer valuable information on fast electron transport and plasma formation at the target rear surface. Initial results from the Astra-Gemini laser are presented, with rapid radial sheath expansion together with detailed filamentary features being observed to evolve during single shots

Improving IEC 61850 interoperability and simplifying IED configuration through the standardisation of protection settings

One of the key benefits of IEC 61850 is that it can facilitate interoperability between Intelligent Electronic Devices (IEDs) from different vendors. However, at present, the scope of interoperability is constrained to communications data, such as Sampled Value (SV) and Generic Object Oriented Substation Events (GOOSE) messaging, and has not been extended to protection setting information. The protection functions are implemented using proprietary parameters and are typically stored in vendor-specific binary files, which make it very difficult to manipulate these data directly from external applications. Engineers must also understand the meaning and implications of modification of all proprietary setting parameters and often need to be trained in the use of vendor-specific tools, which is time consuming and potentially increases the risk of introducing protection setting errors. Furthermore, the existing IED configuration process is complex, involves many steps, and requires the use of various software tools. To address these problems, this paper proposes the use of the IEC 61850 data model and System Configuration description Language (SCL) to represent protection settings. The proprietary protection settings data are mapped to the IEC 61850 standardised data and saved as SCL files. The common representation of protection settings in SCL files can also be interpreted and converted back to proprietary settings, thus achieving protection setting interoperability. A prototype tool that implements the process has been developed and demonstrated by the authors. In the paper, the entire process is described using examples. The SCL files, based on an XML syntax that can be easily manipulated automatically by applications such as protection coordination tools, are used to streamline the existing IED configuration process. A simplified IED configuration process using the SCL based setting files is proposed in the paper. Compared with the existing process, the new process is significantly streamlined, and permits an IED-independent system configuration tool to carry out the entire configuration process. No proprietary software or communications are needed. It also allows the protection settings to be performed at a system level, rather than individually on a “per device” basis. The key challenges that must be addressed in order for the proposed process to be widely adopted are: the IEC 61850 data model for protection settings is not complete; vendors may prefer to maintain proprietary formats; the data model should have the capability to be extended for future protection functions. This paper reports the progress towards addressing these challenges

Integrated electrical and mechanical modelling of integrated-full-electric-propulsion systems

Integrated Full Electric Propulsion (IFEP) systems are the subject of much interest at present. Current research is focused on analysing and improving aspects of subsystem and system performance. However, there is a great need to look more widely at the `multi-physics' problem of characterising the dynamic interactions between the electrical and mechanical systems. This paper will discuss the changing nature of modelling and simulation to aid research into IFEP systems, outlining the alternative angle taken by the Advanced Marine Electrical Propulsion Systems (AMEPS) project to characterise and investigate electrical-mechanical system interactions. The paper will describe this approach and highlight the unique challenges associated with the problem, discussing the suitable methods that will be adopted to address these challenges. Finally, an overview of the present and future research opportunities facilitated via the AMEPS project will be presented

A solution for improved simulation efficiency of a multi-domain marine power system model

Integrated Full Electric Propulsion (IFEP) marine power systems offer increased design flexibility and operational economy by supplying ship propulsion and service loads from a common electrical system. Predicting the behaviour of IFEP systems through simulation is important in reducing the design risk. However, the prevalence of power electronics and the potential for interaction between large electrical and mechanical systems introduce significant simulation challenges. This paper presents an integrated simulation tool, which brings together electrical, mechanical, thermal and hydrodynamic models, facilitating a holistic simulation capability. Approaches adopted for model validation and computational efficiency together with two case studies are discussed

Validating secure and reliable IP/MPLS communications for current differential protection

Current differential protection has stringent real-time communications requirements and it is critical that protection traffic is transmitted securely, i.e., by using appropriate data authentication and encryption methods. This paper demonstrates that real-time encryption of protection traffic in IP/MPLS-based communications networks is possible with negligible impact on performance and system operation. It is also shown how the impact of jitter and asymmetrical delay in real communications networks can be eliminated. These results will provide confidence to power utilities that modern IP/MPLS infrastructure can securely and reliably cater for even the most demanding applications

Disturbance of primary producer communities disrupts the thermal limits of the associated aquatic fauna

Environmental fluctuation forms a framework of variability within which species have evolved. Environmental fluctuation includes predictability, such as diel cycles of aquatic oxygen fluctuation driven by primary producers. Oxygen availability and fluctuation shape the physiological responses of aquatic animals to warming, so that, in theory, oxygen fluctuation could influence their thermal ecology. We describe annual oxygen variability in agricultural drainage channels and show that disruption of oxygen fluctuation through dredging of plants reduces the thermal tolerance of freshwater animals. We compared the temperature responses of snails, amphipods, leeches and mussels exposed to either natural oxygen fluctuation or constant oxygen in situ under different acclimation periods. Oxygen saturation in channel water ranged from c. 0 % saturation at night to >300 % during the day. Temperature showed normal seasonal variation and was almost synchronous with daily oxygen fluctuation. A dredging event in 2020 dramatically reduced dissolved oxygen variability and the correlation between oxygen and temperature was lost. The tolerance of invertebrates to thermal stress was significantly lower when natural fluctuation in oxygen availability was reduced and decoupled from temperature. This highlights the importance of natural cycles of variability and the need to include finer scale effects, including indirect biological effects, in modelling the ecosystem-level consequences of climate change. Furthermore, restoration and management of primary producers in aquatic habitats could be important to improve the thermal protection of aquatic invertebrates and their resistance to environmental variation imposed by climate change

Diel oxygen fluctuation drives the thermal response and metabolic performance of coastal marine ectotherms

Coastal marine systems are characterized by high levels of primary production that result in diel oxygen fluctuations from undersaturation to supersaturation. Constant normoxia, or 100% oxygen saturation, is therefore rare. Since the thermal sensitivity of invertebrates is directly linked to oxygen availability, we hypothesized that (i) the metabolic response of coastal marine invertebrates would be more sensitive to thermal stress when exposed to oxygen supersaturation rather than 100% oxygen saturation and (ii) natural diel fluctuation in oxygen availability rather than constant 100% oxygen saturation is a main driver of the thermal response. We tested the effects of oxygen regime on the metabolic rate, and haemocyanin and lactate levels, of velvet crabs (Necora puber) and blue mussels (Mytilus edulis), under rising temperatures (up to 24°C) in the laboratory. Oxygen supersaturation and photosynthetically induced diel oxygen fluctuation amplified animal metabolic thermal response significantly in both species, demonstrating that the natural variability of oxygen in coastal environments can provide considerable physiological benefits under ocean warming. Our study highlights the significance of integrating ecologically relevant oxygen variability into experimental assessments of animal physiology and thermal response, and predictions of metabolic performance under climate warming. Given the escalating intensity and frequency of climate anomalies, oxygen variation caused by coastal vegetation will likely become increasingly important in mitigating the effects of higher temperatures on coastal fauna