J.D. Schuddebeurs

Propulsion Drive Models for Full Electric Marine Propulsion Systems

Integrated full electric propulsion systems are being introduced across both civil and military marine sectors. Standard power systems analysis packages cover electrical and electromagnetic components, but have limited models of mechanical subsystems and their controllers. Hence electromechanical system interactions between the prime movers, power network and driven loads are poorly understood. This paper reviews available models of the propulsion drive system components: the power converter, motor, propeller and ship. Due to the wide range of time-constants in the system, reduced order models of the power converter are required. A new model using state-averaged models of the inverter and a hybrid model of the rectifier is developed to give an effective solution combining accuracy with speed of simulation and an appropriate interface to the electrical network model. Simulation results for a typical ship manoeuvre are presented.

Modelling and Analysis of Electro-Mechanical Interactions between Prime-Mover and Load in a Marine IFEP System

This paper reports on the simulation of a marine Integrated Electric Full Electric Propulsion (IFEP) system to assess its ability to absorb variations in propulsion or auxiliary load without excessive degradation of the electrical supply quality or imposing excessive demands on the prime movers. IFEP systems are expected to yield economic benefits to ship operators by permitting the capacity of ship engines in use to be more closely tailored to the electrical demand of auxiliary and propulsion systems. However, the extent to which these savings can be realised at times of low demand is dependent on the ability of the shipboard electrical system to absorb disturbances. In this paper, simulations are conducted for a variety of frequencies of load variation, and the results assessed. Measures which might be taken to reduce the observed effects are suggested.

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.

Emerging Research Issues Regarding Integrated-Full-Electric-Propulsion

Integrated full electric propulsion (IFEP) currently provides advantages for both the commercial and naval shipping industries. However, in order to realise the full potential of this concept research into all aspects of IFEP system design and operation is necessary, particularly for naval applications where the operational requirements are more stringent and the need to mitigate the risk associated with the new technology is greater. This paper reviews current IFEP research programmes worldwide and identifies the core research issues under consideration. IFEP programmes such as the Norwegian commercial vessel-orientated EEAES programme and the UK-based ESTD, which is targeted at military applications, are discussed in more detail. This paper maintains that this existing IFEP research is creating further opportunities for research into the system-level dynamic behaviour and argues that such research is necessary to de-risk IFEP design. A simulation case study demonstrating the adverse effects on a marine electrical power system as a result of dynamic loading on the ships propulsion system is also is included in the paper to support this argument

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.

A High Fidelity Integrated System Model for Marine Power Systems

By providing a common power supply to both the propulsion and service loads on ships, integrated full electric propulsion (IFEP) offers benefits of increased design flexibility and reduced running costs. Whilst presenting power system challenges commonly seen in land based grid systems, the prevalence of power electronics, high power density, and the significance of individual loads (such as propulsion drives) creates particular challenges for modelling and simulation tools. Operating challenges also exist, which require the use of multi-disciplinary modelling and simulation to investigate. This paper presents a high fidelity integrated IFEP simulation tool, which contains models from the electrical, mechanical and thermal physical domain. This model enables investigation from a systems level point of view. Some of the key challenges identified in the development of this model are discussed, focusing on aspects such as the existence of different time constants and the difficulties of system validation. The chosen solutions to the challenges listed above are presented and discussed. The effectiveness of the integrated IFEP simulation tool is demonstrated through a case study on the loss of propulsion load.