Series capacitors are used extensively to reduce the power transfer impedance of long transmission lines. During times of high current, the capacitors are protected from the build-up of high voltages by spark gaps with which they are connected in parallel. This non-linearity affects the behaviour of the system as a whole. Firstly, this thesis is concerned with studying the system behaviour. A method of analysing the sub-harmonic resonance condition in which line losses are taken into account is proposed, and it is used to find a power system circuit in which operation changes from harmonic to subharmonic mode when a switch is operated. Also described is a method of achieving a transient stability analysis of a two-machine double-circuit series-compensated transmission system with a fault occurring on one circuit. The results are used to compare the effect of two types of protective spark gap. A transient analysis of a single transmission circuit is described, based upon Bergeron's Method of Characteristics. The spark gap type is shown to be instrumental in distorting current and voltage wave-forms. It is generally assumed that spark gap operation shortens the lifetime of the capacitors which it is protecting. This is investigated and is shown to have some theoretical foundation. Secondly, this thesis is concerned with the problem of finding a suitable distance protection scheme for series compensated lines. A number of possibilities are critically examined by making use of the analysis developed earlier in the thesis. A novel scheme based on definite integrals of relaying current and voltage was selected and a prototype relay was constructed in the laboratory using mostly analogue, but some digital circuits. Laboratory tests on the prototype relay and simulated tests carried out on the digital computer showed that the scheme meets the speed and accuracy requirements of modern protective relay.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:471557 |
| Date | January 1973 |
| Creators | Sanderson, J. V. H. |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://eprints.nottingham.ac.uk/13524/ |
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