Protection polarity checking is an important link in the commissioning of newly-built

expanded and reconstructed substations

and the wrong protection polarity will cause the incorrect action of relay protection device

which will seriously affect the safe and stable operation of power grid. At present

the protection polarity checking mainly depends on manual analysis

and the accuracy of checking results is greatly affected by human factors and its work efficiency is low. In order to improve the accuracy and efficiency of protection polarity checking

a protection polarity checking method based on current angle calculation is proposed. Firstly

the factors affecting the current angle in protection devices are analyzed

and the current angle calculation model is established. Secondly

the current angle is calculated according to the data of switch position

load nature

polar end of current transformer and its extraction mode

and the protection polarity is automatically judged by comparing the calculated current angle with the measured current angle. Finally

the correctness of protection polarity checking method is verified using data such as the test data of startup and commissioning of AC station system of a converter station

and the result shows that the accuracy of this checking method can reach 100%

which proves the correctness of the proposed method.