European Conference on Cognitive Ergonomics 

About: European Conference on Cognitive Ergonomics is an academic conference. The conference publishes majorly in the area(s): Inverter & Capacitor. Over the lifetime, 9935 publications have been published by the conference receiving 71013 citations.

Regions of active damping control for LCL filters

Abstract: The control of a grid connected voltage source inverter (VSI) with an LCL filter is a very challenging task, since the LCL network causes a resonance phenomenon near to the control stability boundary While many active damping methods have been proposed to overcome this issue, the role that PWM transport delay plays in the effectiveness of these strategies is still not fully resolved This paper presents a theoretical discrete time analysis frame work that identifies three distinct regions of LCL filter resonance - a high resonant frequency region where active damping isn't required; a critical resonant frequency where a controller cannot stabilise the system; and a low resonant frequency region where active damping is essential Suitable controllers are then proposed for the two stable regions, with gain calculations that allow for the greatest system bandwidth and damping Simulation and experimental results verify the presented analysis

Measuring Situation Awareness in complex systems: Comparison of measures study

Abstract: Assessing operator situation awareness is a key component of sociotechnical system design and evaluation. This article describes a study that was undertaken in order to compare two different situation awareness measures (a freeze probe recall approach and a post trial subjective rating approach) when used to assess participant situation awareness during a military planning task. The results indicate that only the participant situation awareness scores derived via the freeze probe recall method produced a statistically significant correlation with performance on the planning task and also that there was no significant correlation between the two methods, which suggests that they were measuring different aspects of participant situation awareness during the trials. In conclusion, the findings, whilst raising doubts over the validity of the post trial subjective rating approach, offer validation evidence for the use of freeze probe recall approaches to measure situation awareness during simulated tasks. The findings are subsequently discussed with regard to their wider implications for the future measurement of situation awareness in complex collaborative systems. Relevance to industry Situation Awareness is a critical commodity for teams working in industrial systems. Accordingly, designers and analysts require reliable and valid methods for assessing the impact of new systems, interfaces, training programs and procedures on the level of situation awareness held by operators. This article presents a review and comparison of situation awareness measurement approaches for use in complex industrial systems and provides recommendations on the types of methods to use during future situation awareness assessments.

A novel inner current suppressing method for modular multilevel converters

Abstract: Ideally, the inner (the upper or lower arm) current of a modular multilevel converter (MMC) is assumed to be the sum of a dc component and an ac component of the fundamental frequency. However, this current is usually distorted and the peak/RMS value of it is increased compared with the theoretical result. This is because ac current flows through the submodule (SM) capacitors and the capacitor voltages fluctuate with time. The increased currents will increase power losses and may threaten the safe operation of the power devices and capacitors. This paper proposes a novel close-loop method for suppression of the inner current in MMC. This method is very simple and is implemented in stationary frame, and no harmonic extraction algorithm is needed. Hence, it can be applied to single-phase or three-phase MMC. What is more important, this method does not influence the balancing of the SM capacitor voltages. Simulation and experimental results show that the proposed method can suppress the peak and RMS values of the inner currents dramatically. Meanwhile, the harmonic contents in the output current can also be suppressed satisfactorily even when the SM capacitor voltage ripple factor is as large as about ±19%. Therefore, the proposed method can also be adopted to reduce the SM capacitance requirement.

Review of solid state transformer in the distribution system: From components to field application

Abstract: The emergence of high power converters makes the modern power grid more active than it was before. One of the research directions in this area is the solid state transformer, which aims at replacing the traditional 50/60 Hz power transformer by means of high frequency isolated AC/AC solid state conversion techniques. This paper presents a systematical technology review essential for the development of solid state transformer in the distribution system, especially focusing on the following four areas: high voltage and high frequency power devices, high power and high frequency transformers, AC/AC converter topologies, and applications of solid state transformer in the distribution system. For each category, the state-of-art technologies are reviewed and possible research directions are presented. It is concluded that the solid state transformer is an emerging technology for the modernization of the future smart grid.

Volume/weight/cost comparison of a 1MVA 10 kV/400 V solid-state against a conventional low-frequency distribution transformer

Abstract: Solid-State Transformers (SSTs) are an emergent topic in the context of the Smart Grid paradigm, where SSTs could replace conventional passive transformers to add flexibility and controllability, such as power routing capabilities or reactive power compensation, to the grid. This paper presents a com- parison of a 1000kVA three-phase, low-frequency distribution transformer (LFT) and an equally rated SST, with respect to volume, weight, losses, and material costs, where the correspond- ing data of the SST is partly based on a full-scale prototype design. It is found that the SST's costs are at least five times and its losses about three times higher, its weight similar but its volume reduced to less than 80%. In addition, an AC/DC application is also considered, where the comparison turns out in favor of the SST-based concept, since its losses are only about half compared to the LFT-based system, and the volume and the weight are reduced to about one third, whereas the material costs advantage of the LFT is much less pronounced. I. INTRODUCTION