| 1. |
- Souza, Lamartine, et al.
(författare)
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Impact of Non-Stationary Noise on xDSL Systems: an Experimental Analysis
- 2007
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. ; 6603
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Konferensbidrag (refereegranskat)abstract
- Broadband services require data rates that can only be achieved by using relatively high spectrum frequencies. At such high frequencies, the DSL (Digital Subscriber Line) signal is more susceptible to external noise sources, such as radio frequency interference and impulsive noise. This paper aims to characterize how the impulsive noise impacts on services and applications for a broadband system using an ADSL2+ loop. The first approach was to use the impulsive noise defined in the standards G.996.1 (Test Procedures for DSL Transceivers) from ITU-T and TR-048 (ADSL Interoperability Test Plan) from DSL Forum. In this approach we have also used a HDSL (High Bit Rate DSL) and white noise disturbers on the line. The impulsive noises c1 and c2 (defined in G.996.1) are injected into the circuit at the CO (Central Office) end and CPE (Customer Premises Equipment) end of the loop simulator. Additionally, it was analyzed the spikes of noise's impact on the ADSL2+ line. In this case, pre-defined models of NEXT (Near-end crosstalk) and white noise are injected on CO and CPE side, simultaneously. Metrics like packet rate, lost packet count, bandwidth, short-term average transfer delay, and errored seconds are used to characterize the DSL loop under the noise impairments.
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| 2. |
- Vanfretti, Luigi, et al.
(författare)
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Fundamental Analysis of the Synchronous Generator : TCSC System using the ICAD Framework
- 2008
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Konferensbidrag (refereegranskat)abstract
- The TCSC, a mature member of the FACTS technology, is the electronically-controlled counterpart of the conventional series bank of capacitors. Its major bene-fits are its ability to regulate power flows along the com-pensated line and to rapidly modulate its effective imped-ance. In this paper, fundamental analysis of the synchro-nous generator – TCSC system using Individual Channel Analysis and Design, is carried out. The main benefits of this approach in control system design tasks are elucidated. Fundamental analysis is used to explain the generator dynamic behaviour as affected by the TCSC. The system is modelled as a 3x3 multivariable plant. Moreover, a control system design for the system is presented, with particular emphasis in the closed-loop performance and stability and structural robustness assessment. The percentage of series compensation is varied (50, 25 and 10%) by changing the firing angle of the TCSC. It is formally shown that the addition of the TCSC improves the dynamical performance of the synchronous machine by substantially decreasing the electrical distance and therefore considerably reducing the awkward switch-back characteristic exhibited by synchro-nous generators. However, the TCSC inclusion brings on fragility to the global system, making it non-minimum phase and introducing adverse dynamics in the speed channel of the synchronous machine.
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