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Room Temperature Vulcanization (RTV) anti-pollution flash-over coating used in electric power external insulation has been widely painted in Northern Chinese HVAC / HVDC transmission lines, especially in Tianjin, all insulators are coated. This paper takes RTV coating's life assessment, focusing pollution interlayer affect on re-coating. Through the analysis of the original coating's properties, such...
Synchronous sampling data is essential for conventional busbar differential protection however, with the advancement in smart substation and distributed busbar protection scheme, there is a need in researching novel differential protection approaches which are immune to asynchronous sampling data. This paper presents a new method of busbar differential protection which can eliminate the impact of...
This paper examines the dynamic performance of a vector-current controlled unified power flow controller (UPFC) to be installed in an actual Chinese power network. This first UPFC of China, with a total rating of ±120MVA, has been in full operation since the end of 2015. This paper establishes the non-linear dynamic mathematical model of the vector-current controlled UPFC to be installed in the power...
Measuring electric field has a very wide range of applications in the power system, but for the ion field under the HVDC transmission lines, the current measurements are insufficient. In this paper, effects of interventional measurement, theoretical analysis, measuring programs are researched. Sensors in a Poisson field sense an electric field Ein, which consists of three parts. E0 is the origin electric...
With the fast development of offshore wind farm, the cost-effective collection and transmission of large-scale offshore wind power has been an increasing concern. To better integrate the HVDC technology to the future offshore wind farms, advanced concepts of DC-DC power conversion and DC wind turbines can be extended to all-DC wind farm design. The state-of-art of three key technologies of the offshore...
Virtual synchronous generator (VSG) is grid-friendly for integrating distributed generations (DGS). However, because of the fluctuation of DGs power input, VSG frequency oscillation may occur and cannot operate stable with traditional control scheme. To solve this problem, an adaptive damping control strategy of VSG is proposed. Firstly, the principle of VSG frequency oscillation produced by power...
As one of the key procedures in preliminary design, the project location of unified power flow controller (UPFC in short) plays a decisive role in improving control effect. Usually the quantity of UPFC devices is limited considering social and economic factors, thus the optimization objective of project location is to make use of limited UPFC to the largest extend. Therefore, a practical algorithm...
HVDC for long-distance power transmission is of many significant technique advantages. Wind generation bundled with the support by conventional thermal generation enables the generation controllable and more suitable for being sent over to remote load centre. Hence Wind-thermal-bundled power transmission by AC/DC system and its coordinated control has become an actively pursued research subject recently...
The application of 500kV insulating aerial device to provide technical means for safety and reliability of power transmission lines, but influence of conductive work platform on the insulation of towet windows gaps are not clear. The switching discharge tests were applied to determine the minimum approach distance in live working. Firstly, test samples were processed according to the typical single...
There are limited spaces for the fast increasing, highly concentrated loads in urban distribution networks. This paper proposes a medium voltage hybrid AC/DC distribution network, in which some AC lines are converted to DC ones, and interconnected with voltage source converter (VSC). A control strategy is also established to increase transfer capacity and DG accommodation. The economic evaluation...
Urban area is the major load centre of power system. To meet N-1-1 criterion is important for an urban grid with the requirement of high power supply reliability. The considerations of N-1-1 criterion in overseas developed areas are compared in this paper. The impact of the configuration of substations and the inter-connections on power supply reliability is analysed for the grid under N-1-1 condition...
There is increasing interest in interconnecting individual wind turbines in offshore wind farms using DC networks rather than AC networks. As the output from each turbine/generator is normally low (less than 6 kV), DC-DC converters may be required to step-up the voltage to an intermediate level to interconnect the turbine outputs, and another DC-DC converter to step-up this intermediate voltage to...
Much attention has been focused on the reactive power support and voltage stability problem in power system, the VSC-HVDC technology provides a new measure to the voltage control in power system due to its flexible power regulation performance. A reactive power optimization model for a power grid including multi-terminal VSC-HVDC is presented in the paper. Regulation cost of changing transformer tap,...
This paper studies the power flow control of two LCC-HVDCs interconnected through DC-DC Autotransformer. The interconnecting scheme and its potential benefits are firstly summarized. Natural instability of using conventional LCC controller in the interconnected system is identified. To solve the instability issue, local power flow controller and centralized power flow controller are designed. Simulations...
The EHVDC transmission systems have the advantages of long-distance and high-capacity power transmission capability, in order to better play the advantages of the EHVDC transmission systems mentioned above, State Grid Corporation of China (SGCC) had proposed to increase the transmission capacity of ±660kV UHVDC transmission system, and increase the bipolar rated capacity from 4000MW to 4600MW, and...
Bird damage is one of the most important factors that threaten the safety and stability of DC transmission line. In order to solve the gap breakdown problem caused by bird damage, this research provides the method of figuring out the risk region of tower. The ±400kV tangent tower model was based on altitude correction of discharge voltage in high altitudes. Three-dimensional finite element model was...
A positive- and negative-sequence control strategy, which is suitable for both balanced and unbalanced voltage sags, is investigated to improve the injection current quality of gird-connected photovoltaic (PV) systems under unbalanced voltage conditions. Under the control strategy, the fault current is limited without negative current injection and it helps enhance the low voltage ride-through (LVRT)...
The metallic grounding material such as copper, steel and alloys plating used in power system nowadays are facing lots of problems such as corrosion, high maintenance cost and so on. To solve these problems, a new type of grounding material — the flexible graphite-copper composited grounding material (FGCG) was proposed and produced. The raw materials include high purity graphite, copper, organic...
As long as the appearance and continual commission of the wind-thermal-bundled (WTB) high-voltage direct current (HVDC) transmission system, in order to ensure security and stability, it is necessary to carry out further study on the reactive power/voltage interaction among wind turbine generators (WTG), thermal generators (TG) and HVDCs. Firstly, the mechanism and corresponding measures of WTG overvoltage...
Low frequency AC (LFAC) has been proposed as a means to avoid some of the large converter station costs of high voltage DC (HVDC) while delivering some of the benefits in terms of better cable utilization and its technical feasibility has been established. It is said to offer lower costs than HVDC or conventional high voltage AC (HVAC) for a range of intermediate distances, with HVDC becoming cheaper...
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