Change search

Cite
Citation style
• apa
• ieee
• modern-language-association-8th-edition
• vancouver
• apa.csl
• Other style
More styles
Language
• de-DE
• en-GB
• en-US
• fi-FI
• nn-NO
• nn-NB
• sv-SE
• Other locale
More languages
Output format
• html
• text
• asciidoc
• rtf
Inkoppling av en asynkrongenerator
2002 (Swedish)Independent thesis Basic level (professional degree)Student thesis

##### Abstract [en]

The purpose of this engineering degree project is to study the transients that occur when an induction generator is connected to the electric grid. The project was initiated by Birka Nät in Karlstad. As a model for the projekt I have used the power station in Kolsäter in Arvika. The station are at 540 kW/0,4 kV and the voltage are transformed into 10,5 kW via a 4,75 km long ground-cable on to the region-network. It is generally known that induction machines cause a considerable inrush current when connected to the grid. This may cause unacceptable voltage transients in the grid. I have studied which parameters influence the voltage transients in order to find ways of smoothening them. As my main tool I have used the simulation program Simpow from ABB. In Simpow there are ready-to-use models for components e.g. generators. The program also contains excellent tools for analysing transient phenomena. A major problem was to find circuit parameters for generators. I want to express my gratitude to Mr Tore Pettersson of ABB who furnished me with all typical machine parameters. After setting up a model for a typical induction generator and the adjacent electric grid, I performed simulations to investigate the behaviour of the system. The simulations functioned well and gave results well in accordance with what can be expected. The first parameter I studied was the generatorparameters, rotor/stator resistance, rotor/stator reactance. I changed the parameters +/- 50 % and run a simulation on each change. I found that the influence the maximal voltage drop was small only by a few percent. It was the leakage reactance that where the most important factor. I also performed sensitivity analyses with respect to parameters R, X and C (resistance, inductive reactance and capacitance of the grid), which in principle are the only grid parameters that can be manipulated. Birka Nät had expressed a particular interest in the influence of the X/R ratio. Thus, I applied X/R values of 0.5, 1.0, 2.0 and 4.0. In a “normal” grid with a short circuit impedance of 4 – 6 W, I found that the X/R ratio only influences the maximal voltage drop by some 5 – 6 %. In a “weak” grid with a short circuit impedance of 10 W, the influence is as big as 10 %. The smallest voltage drop will occur when the X/R ratio assumes it lowest value. Another important parameter, which I have studied, is the initial slip of the machine, i.e. the slip in the moment when it is connected to the grid. I found that the initial slip is of practically no importance for the inrush current or the voltage drop. However, it greatly influences the electrical torque and the duration time of the connection transients. In this respect, a zero slip will give the smoothest connection, while a higher slip will cause fluctuations of the electrical torque which will “jerk” the machine and cause unnecessary wear.

2002. , p. 53
##### Identifiers
Local ID: ELI-6OAI: oai:DiVA.org:kau-54279DiVA, id: diva2:1102981
##### Subject / course
Electronic Engineering, Bachelor of Science
Available from: 2017-05-30 Created: 2017-05-30

#### Open Access in DiVA

No full text in DiVA

urn-nbn

#### Altmetric score

urn-nbn
Total: 675 hits

Cite
Citation style
• apa
• ieee
• modern-language-association-8th-edition
• vancouver
• apa.csl
• Other style
More styles
Language
• de-DE
• en-GB
• en-US
• fi-FI
• nn-NO
• nn-NB
• sv-SE
• Other locale
More languages
Output format
• html
• text
• asciidoc
• rtf