Impacts of UHV on Short Circuit Currents in China's Central 500kV Grid and Its Countermeasures

Ultra-high voltage (UHV) projects are making power system growing lager and resulting in sharp increase of short circuit currents in some area especially in the vicinity of UHV access points. The paper presented the damage of short circuit current increases and common methods to limit fault current. Taking the construction and development of UHV grid in a province of central China as background, the over short circuit currents in 500kV Grid within UHV were showed and several countermeasures including choosing proper UHV access scheme, implementing UHV substation lower voltage bus partition running, installing reactors, optimizing power grid network based on UHV connection point were proposed and then verified by PSASP simulation. The results show those measures are useful to reduce the short circuit current to a reasonable level.