| 1. |
- Akke, Magnus, et al.
(författare)
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An object-oriented transformer model in OMOLA
- 1997
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Ingår i: Proceedings of the world congress - International federation of Automatic Control. - 0080429262 ; , s. 259-264
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Konferensbidrag (refereegranskat)
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| 2. |
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| 3. |
- Akke, Magnus
(författare)
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Fault classification for distance protection
- 2002
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Ingår i: IEEE/PES Transmission and Distribution Conference and Exhibition 2002: Asia Pacific. - 0780375254 ; 2, s. 835-839
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Konferensbidrag (refereegranskat)abstract
- This paper presents an overview of power system fault classification methods and challenges. It also contains some ideas about structured testing.
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| 4. |
- Akke, Magnus
(författare)
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Frequency estimation by demodulation of two complex signals
- 1997
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Ingår i: IEEE Transactions on Power Delivery. - : Institute of Electrical and Electronics Engineers (IEEE). - 1937-4208 .- 0885-8977. ; 12:1, s. 157-163
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a method for frequency estimation in a power system by demodulation of two complex signals. In power system analysis, the αβ-transform is used to convert three phase quantities to a complex quantity where the real part is the in-phase component and the imaginary part is the quadrature component. This complex signal is demodulated with a known complex phasor rotating in opposite direction to the input. The advantage of this method is that the demodulation does not introduce a double frequency component. For signals with high signal to noise ratio, the filtering demand for the double frequency component can often limit the speed of the frequency estimator. Hence, the method can improve fast frequency estimation of signals with good noise properties. The method loses its benefits for noisy signals, where the filter design is governed by the demand to filter harmonics and white noise. The method has been previously published, but not explored to its potential. The paper presents four examples to illustrate the strengths and weaknesses of the method.
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| 5. |
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| 6. |
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| 7. |
- Akke, Magnus, et al.
(författare)
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Improved estimates from the differential equation algorithm by median post-filtering
- 1997
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Ingår i: Sixth International Conference on Developments in Power System Protection (Conf. Publ. No. 434). - : IEE. - 0537-9989. - 0852966725 ; :434, s. 235-238
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Konferensbidrag (refereegranskat)abstract
- Fast line relaying algorithms are motivated by the need to keep the fault clearing time as short as possible. Fast fault clearing reduces the risk for transient instability, thermal stress on equipment and risk for personnel injuries. There exists, at least, three different themes in transmission line protection: impedance algorithms differential equation algorithms (DEA); and travelling wave algorithms. This paper focuses on the differential equation algorithm. The paper presents the equations used in the differential equation algorithm. Both the continuous-time and the discrete-time equations are given. The very poor estimates are explained by the equations determinant. At some isolated points the determinant approaches zero and the equations become singular. This results in useless, often extreme, estimates. A simulation shows that a linear post-filter is unsuitable for this problem. To solve the problem we suggest a median post-filter. This filter type totally rejects the extreme values, and therefore produce fast and accurate estimates.
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| 8. |
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| 9. |
- Akke, Magnus, et al.
(författare)
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Measurements of the frequency-dependent impedance of a thin wire with ground return
- 2005
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Ingår i: IEEE Transactions on Power Delivery. - 1937-4208. ; 20:2, s. 1748-1752
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of the frequency-dependent impedance of a thin wire with ground return is performed. We argue that the results from a downscaled experimental setup are useful and relevant for power-line applications. The experimental result is compared with two categories of line models. The first category is a model that uses fixed line parameters and the second category consists of models where the inductance and the resistance are frequency dependent. As expected, the frequency-dependent line parameters must be used in the modeling for consistency with the measurements. The result shows that measurements are important to determine the accuracy and limitations of different simulation models.
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| 10. |
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