Dynamic relay testing to evaluate Differential protection malfunctions

Relays play an important role in protection systems. Properly working protection devices result in clearing a fault or decreasing the effect of disturbances on power system.The maloperation of relays can inversely worsen the problem and even deteriorate system stability. Several cases of abnormal maloperation of the transformer differential protection are reported, which occurs when a type of transient current, such as lightning, is applied to the transformer involved power systems. In order to ensure reliable operation, dynamic test as one of the most important test methods for evaluation of protection relays performance has been utilized. With today’s modern test equipment, power system real conditions can easily be simulated. By making a profile of the operation of the scheme, malfunctions can be foundfaster because it is easier to identify the changes in areas that don t operate the way they are expected.The purpose of Dynamic test is to understand the accuracy of protection relay in critical conditions. To reach the point, the survey has been done in a MiCOM P632 differential protection under a real current fault created by a powerful lightning current which happened to a high voltage station of BREC. The relay causes a 230/63KV power transformer to be tripped wrongly. In order to analyze the event, the test has been done by Vebko AMT105 in transient mode. Finally, applying a comtrade file of the fault to Siemens 7UT613, has confir med the maloperation of MiCOM P632 differential relay.

کلیدواژه ها:

component ، dynamic testing ، differential protection ، relay