The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Cross-voltage faults, i.e. multi-circuit faults that occur between different voltage level systems, in mixed-voltage quadruple-circuit transmission lines occur at times. The short-circuit calculations, which are the basis of the relay protection settings, for different faults are required. This study proposes a new method based on the theory of multiple fault analysis. First, the cross-voltage fault...
1000 kV ultra-high voltage (UHV) power transformer plays an important role for HVAC transmission in China. The voltage-regulating transformer (VRT) is an independent part of the UHV power transformer and the exclusive differential protection is needed. The voltage regulation of VRT can range from 0 to 100% which takes great challenges for the differential protection. In engineering, a fixed tap ratio,...
Large oil-immersed power transformers always have the gas relay equipped between the main tank and conservator. However, due to the inherent defects, the gas relay malfunction caused by external faults happens occasionally all over the world, which jeopardizes the safe operation of bulk power systems. In order to explore the oil flow characteristics inside the pipe during external short circuit faults,...
Based on the structures and operating principles of the thyristor controlled transformer-type controllable shunt reactor (TCTCSR), the performance of differential protection for this type of devices is studied. For TCTCSR, differential protection may not be reliable or sensible to the turn-to-turn fault and short-circuit fault of thyristors on the control winding (CtrW). To avoid the dead zone of...
According to a field case on the mal-operation of transformer differential protection in the ultra-high voltage (UHV) experiment project in China, a new scheme of second harmonic blocking criterion is proposed in this paper. Based on the simulation model of UHV transformer established in MATLAB/SIMULINK, the causes of mal-operation is analyzed. The factors such as initial angle and remnant flux which...
The circulating current on the delta side of wye-delta connected three-phase power transformer is hard to measure. The differential transformer protection has to adopt current phase compensation method to compensate the circulating current. However, the differential current hardly reflect the magnetic exciting current of transformer no matter what kind of current phase compensation methods used. It...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.