This paper examines the stability of a weak island namely Sumbawa-Lombok of Indonesian grid, interconnected with two infeed HVDC links facilitating 2 x 120 MW power transfer from Sumba and Flores Island. Through power flow, short circuit, small signal stability, resonance stability, and transient stability analyses, it is demonstrated that the existing infrastructure fails to support such transfer due to voltage drops, overloading, and stability limitations. Upgrading to 150 kV and its subsequent component resolves the small-signal and transient stability constraint as its grid strength is increasing. The current findings underscore that the primary limitation lies in the grid's infrastructure, not in dynamic or control constraints. The current result establishes the need for strategic grid reinforcements to support HVDC integration in weak systems and sets the stage for future research on optimizing the extent of such reinforcements.
The report focuses on analysing on-deck accidents in offshore environments using data from the Health and Safety Executive (HSE) which covers the period 1980-2005. It applies the Accident Anatomy (AA) method, which maps accident causes and consequences using fault trees and cause-consequence diagrams (CCDs). Unlike previous analyses, this report aims to extract deeper insights into accident patterns beyond general statistics.
For this report, on-deck operations involve material handling, tool use, and equipment operation in offshore environments.
The study analysed 10,846 records that cover accident events on both fixed and floating offshore units. The report focuses on cases where injuries or fatalities occurred. The analysis described in the report mapped 77 accident-prone operations and provides a detailed causal understanding of offshore accidents.
Despite the exhaustiveness of the analysis, there are limitations related to the used data. The HSE records primarily document physical and operational aspects of the accidents, leaving out design-related or organisational factors. Next, probabilities for the accident events considered in the analysis are not provided. This is due to the incomplete nature of the sources and the lack of information on the number of opportunities for accidents. The computation of probabilities will be feasible if data on the frequency of use of relevant components, machines, personnel, and workplaces has been also collected.
Slugging flow in offshore oil & gas multi-phase transportation pipelines cause big challenges as the flow regime induces flow and pressure oscillations in the multi-phase pipelines. The negative impacts of the most severe slugs are significant and thus the elimination of slugging flow in the pipelines is a highly investigated topic. To eliminate the slug in an online manner real-time slug detection methods are often required. Traditionally topside pressure transmitters upstream of a 3-phase separator have been used as the controlled variable. In this paper Electrical Resistivity Tomography (ERT) has been examined as an alternative to the traditional pressure transmitters. A lab-scaled testing facility has been constructed in order to obtain test data from an ERT transmitter with 12 probes. Different flow regimes have been generated by a pump and a compressor where 2-phase flow can be tested. Based on the results, the study concludes that the ERT is able to detect the slug very well when the oil and water are well mixed. Furthermore, the traditional pressure transmitters have the limitation that pressure variations can be caused by other operating conditions than slug, such as change in the back pressure from control valves. The biggest limitation using ERT is the lack of ability to distinguish between gas and oil, and thus the ERT can only be used as an effective slug detect measurement when the oil-to-water ratio is low.