Measuring harmonics in high voltage power systems with inductive
and in particular capacitive voltage transformers, CVTs, may cause large
errors. Test carried out by The Norwegian National Grid Company
(Statnett), Bergenshalvoens Kommunale Kraftselskap (BKK) and The
Norwegian Electric Power Research Institute (now SINTEF Energy Research)
revealed errors from 80% to +1200% (0,2-12 pu) of correct values.
Inductive voltage transformers did have a relatively small error up to
29th harmonic (1450 Hz) while capacitive voltage transformers
had large errors at a few hundred Hz. Carrying out calibration tests on
voltage transformers and capacitive voltage transformers in particular
may correct most of the errors. Still inductive voltage transformers
should be preferred for harmonic measurements where possible
"Badania wykonano w ramach programu kalibracji przekładników in situ. W publikacji  zaprezentowano odpowiedź częstotliwościową kilku przekładników pojemnościowych i indukcyjnych zainstalowanych w sieci wysokiego napięcia norweskiego systemu elektroenergetycznego. Podobne zagadnienia podjęli autorzy artykułu , przedstawiając analizę dokładności pomiaru harmonicznych przez przekładniki średniego napięcia w zakresie częstotliwości do 10 kHz. "
[Show abstract][Hide abstract] ABSTRACT: In the paper the comparative analysis of voltage harmonics measurements performed in the transmission network of 400 kV is presented. The voltage were measured using three measuring instruments: resistive voltage divider, inductive voltage transformer and capacitive voltage transformer. Measurement errors were estimated for transformers with reference to the harmonic values obtained with the use of the voltage divider.
[Show abstract][Hide abstract] ABSTRACT: This thesis deals with ground fault location in subtransmission networks. The main subject of the thesis is transient based ground fault location using low frequency fault generated transients. However, the thesis also considers the conventional fault location methods and reviews the various other methods. Low frequency transient based methods, in general, are more precise and more reliable than the conventional methods based on fundamental frequency. They also avoid the need for further investment in existing systems that would be required, for example, for the implementation of travelling wave fault location, as existing transient recorders can be used. As a byproduct of the thorough investigation of conventional fault location and the presentation of its properties and limitations, a new error estimation technique is proposed. Fault generated transients are presented and tested, and their potential to aid fault location using the phase or neutral current is studied. The thesis also tries to solve some of the problems related to fault transient generation and propagation, as well as measurements and signal processing. The network configuration and transformer neutral grounding type receive special attention. The thesis shows the network conditions under which the method works reliably and accurately, and for critical conditions it proposes appropriate correction factors. The studies are performed for the 110 kV overhead lines under the jurisdiction of Fingrid (the Finnish electricity transmission system operator) for all kinds of neutral configurations. The EMTP/ATP software package is used as the network simulator. The results of the simulations as well as real ground fault recordings are analysed and processed in a fault locator developed by the author and implemented in Matlab. TKK dissertations, ISSN 1795-4584; 42
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