Uhv Transmission System Over-voltage And Restrictions

Our country's electric undertaking develop very fast since the reform and opening to the outside world. It is forecast that the installed generating capacity will be 11～12 hundred million kilowatt in the 2020. And the energy sources and the loads is very disequilibrium. The energy sources is centralized in the Midwest area of our country, but the loads is centralized in the east area where the economy is very develop. So it is necessary that construct the energy's alleyway to realize the west electric energy is delivered to the east and the north electric energy is delivered to south. But the extra high voltage transmission network exists some problems that are the alleyway of the transmit electricity is lacking, the electric transport capacity is deficient and the switch off capacity of the breakers is smaller etc. So the EHV transmission network isn't charge with the task of transmit huge electricity. However it is not only improve the transmission capacity and reduce the ullage of the electric energy and the investing cost of power houses but also stint the floor space and play down the short circuit current to construct the ultra high voltage (UHV) transmission system.The allowable voltage peak value of UHV transmission line is directly associated with the factors such as insulation of the electric facility and the transmission line .It's economic benefit is very huge. So it is necessary to investigate the measures which is restrained the overvoltage inside the power system. The paper particularly analysis the frequency overvoltage and the switching surge. And author give some measures to restrain the overvoltage inside the power system. About the power frequency overvoltage,the author particularly studys the effect of the shunt reactor. And against single-phase recluse the breaker,the author researchs the shunt reactor's midpoint earthing by the reactor which capacity is smaller. About the switching, the author particularly analysis the single-phase and three-phase reclose the breaker. And he also studies some measures which restrain the overvlotage, they are using breaker with shunting resistance and using the metal oxide arrester which is furnished in the transmission lines.In the article ,the author carries on a great deal of simulations against the UHV experimental line: Jindongnan-Nanyang-Jingmen with the PSCAD/EMTDC simulation software and draws some conclusions.