Improving power supply capacity of Shanghai 220 kV district gird by controlling short circuit current

Based upon the operating condition of the Shanghai 220 kV grid district, the features of the short circuit capacity of the 220 kV district grid are analyzed. It is pointed out that the present short circuit capacity cannot meet the operation requirements and at the same time the corresponding remedy measures are suggested. In the detailed analysis, the effects of the various adopted measures upon the control of the 220 kV short circuit current and the increase of the available power supply are compared. The measures compared include for example the increase of impedance between the 500 kV and 220 kV short circuit points and the enhancement of the transient impedance of the generators. Finally it is verified that the reactors cannot be used in the control of the 220 kV grid short circuit current.