This paper presents the results of VFTO measure-ment at Guanting substation.By analyzing the oscillograms,characteristics of VFTO are achieved,including times of the arc restrike between the contacts of disconnectors,remnant voltage caused by trapped charge,VFTO′s duration,magnitude,rise rate,and frequency.The possible maximum of the magnitude and rise rate,estimated through an extrapolation method,are 2.46 pu and 12.64 pu/μs respectively.The research indicates that equipping closing/opening resistors in disconnectors is an effective way to suppress VFTO.

Under the background of large-scale wind farms connected with power gird in China,for the hydrothermal power system,this paper combines with load characteristics’change of power grid connected with large-scale wind farms,proposes and analyzes a more close to the actual calculation method for peak load regulation ability,which is available for reference to the study on the actual peak load regulation ability of power grid connected with large-scale wind farms.

In recent years, the power load in Northwest China has been increasing rapidly. However, the structure of growth is unreasonable and is greatly affected by the macrocontrol policies of the central government. In order to deepen the understanding of the power load characteristics in Northwest China power grid, this paper analyzes the load characteristics and electricity consumption structure based on the historical load and electricity consumption data, finds out the main factors affecting load characteristics, and then compares the load characteristics and electricity consumption structure with that in Central and East China. Finally, it summarizes the study results and provides some suggestions.

Ningxia Hui Autonomous Region is rich in resources of wind energy and solar energy,so the new energy resources-based generation develops rapidly in Ningxia.According to the historical statistical data of new energy resource-based generation and load in Ningxia region as well as the prediction data of Ningxia power grid planning,the related factors impacting Ningxia region's ability of admitting new energy resources,including output characteristics of new energy resources,load characteristics in Ningxia region,performance of generation units in Ningxia power grid and the channel to transmit power outwards from Ningxia power grid,are analyzed in detail.It is pointed out that when new energy resources take part in peak-load regulation the annual network loss can be reduced and the power transmission outwards by HVDC power transmission will arise the peak load regulation ability of new energy resource-based generation provided by power grid;however,the complementarity between wind power generation and photovoltaic generation is not satisfied and it is not favorable to power grid to admit new energy resource,otherwise,the load characteristic of power grid will usually be deteriorated under the connection of new energy source-based generation with power grid.These research results could be available for further research on Ningxia power grid's ability to admit new energy resource-based generation and the dispatching of Ningxia power grid while new energy resource-based generation is connected to Ningxia power grid.

It is the first time since Sept.2005 when the 750 kV transmission pilot project in Northwest China for GuantingSubstation was put into commercial operation,that the Very Fast Transient Overvoltage(VFTO)in the 750 kV GIS was tested in field.In the test, the disconnecting switchgears(DS)in the 750 kV GIS were switched normally,with one side or both sides charged by the system voltage. Quite a number ofdata and oscillographs are acquired,valuable for analyzingand understandingthe characteristics ofVFTO.The field testing of VFTO and the main results is overviewed.Furthermore, sugg-ests are put forward for improving the switching of DS in 750 kV GIS.

The development progress of 750 kV and ultra-high voltage (UHV) in Russian is outlined in this paper firstly. Sequentially, the Russian 750 kV and UHV power grid construc-tion progress, transmission technology are summarized. Moreover, the status of international power transmission between Russian and China are reviewed. Finally, combined with the current actual power grid situation in China, some new ideas are further proposed.