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.
In order to determine the insulation level of DC transmission line, one UHV DC transmission project is taken as an example in this paper. PSCAD program is used to establish the simulation calculation model. Multiple fault points on the fault line are selected. The induced overvoltage amplitude, distribution along the line and the maximum overvoltage envelope of healthy pole transmission line corresponding...
Besides offshore applications, MMC-HVDC is discussed for embedded onshore structures. In contrast to their maritime counterparts, these systems shall be carried out with overhead transmission lines to minimize investment costs. To avoid a full outage in case of a dc fault, bipolar topologies seem advantageous considering reliability aspects. While ground currents during asymmetric operation are unwanted,...
This work presents a discussion on the traditional methodologies presented by CIGRE and IEEE to calculate the lightning outage rate of high voltage transmission lines in terms of backflashover occurrence. The main aspects of such methodologies are reviewed. The simplifications and approximations adopted to determine the outage rate are discussed. Systematic simulations are developed considering a...
This recommended practice specifies the procedure for selection of insulation levels of UHV AC transmission lines and substations. It also specifies reliability criterion under switching overvoltage and lightning overvoltage. It also suggests the calculation methods of insulation coordination design. According to the characteristics of UHV AC systems, overvoltages mitigation measures are recommended...
Induced voltage working procedures for underground transmission circuits are established in this guide. A transmission circuit when de-energized will have an induced voltage when in a common duct bank with an energized circuit. The induced voltage may be a possible safety hazard. The induced voltage may be determined by modeling the circuits and by measurement. This guide addresses the working procedures...
The relevance of subsequent strokes as source of backflashovers is assessed from simulations using the hybrid electromagnetic model for transmission lines with distinct voltage levels. It was found that, in spite of the effectiveness of the usual practice of reducing tower-footing grounding resistance to decrease the lightning overvoltage developed across insulator strings for first-stroke currents,...
The ultra high voltage current (UHVDC) is the important technical means for the solution of high voltage, large capacity, and long distance power transmission. plusmn800 KV UHVDC transmission technology will be used in the project which transfer hydroelectric power in Yunnan Province and Sichuan Province to Guangdong Province and Shanghai and other east places in China. During the building course...
Rapid increase of the transmission capacity and environmental limit of the power transmission passage have indispensably promoted development of the AC/DC hybrid transmission lines on the same tower, especially for UHV systems being established in China. Unfortunately, severe electromagnetic coupling effects will inevitably exist between the UHV AC and DC transmission lines built on the same tower...
This paper focus on lightning disturbance on 110 kV transmission line in Anhui Chizhou electric power supply company, and discovers that, most of lightning disturbances happened in mountainous area are counterattack, which are caused by lightning striking on overhead tower or shielding wires, but in some special area, shielding failure also happens sometimes. Based on mechanism of counterattack and...
Reducing dead time of high voltage power transmission lines is one of the most important issues in power system protection. Besides, need for reducing the dead time is a matter of grave concern to increase voltage level of power transmission lines and insulation coordination. In this paper, different methods for decreasing the capacitive coupling and consequently reducing the dead time of power transmission...
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.