Method and device for monitoring a three-phase network operated in a compensated manner for a tuning change of the arc suppression coil
A method for monitoring a three-phase network that is operated in a compensated manner for a tuning change of the arc suppression coil. Reference network parameters and a reference network frequency are determined for a tuned state, and a current network frequency is determined for a current state. A reference characteristic variable, which is proportional to a displacement voltage, is determined for the current network frequency using the reference network parameters, and a current characteristic variable, which is proportional to a displacement voltage, is determined at the current network frequency. A differential variable is determined from the reference characteristic variable and the current characteristic variable, from which, with a predetermined threshold value being exceeded, a tuning change is identified and changed network parameters are determined.
1 . A method for monitoring a three-phase power network operated in a compensated manner for a tuning change of an arc suppression coil, the method which comprises:
ascertaining reference network parameters and a reference network frequency for a tuned state;
ascertaining a current network frequency for a current state;
determining a reference characteristic variable, which is proportional to a displacement voltage, using the reference network parameters for the current network frequency;
determining a current characteristic variable, which is proportional to a displacement voltage, at the current network frequency;
determining a differential variable from the reference characteristic variable and the current characteristic variable, and identifying a tuning change from the differential variable when a predetermined threshold value is exceeded, and ascertaining modified network parameters; and
performing a tuning procedure to tune the arc suppression coil based on the modified network parameters ascertained.
2 . The method according to claim 1 , wherein each of the reference characteristic variable and the current characteristic variable is a displacement voltage.
3 . The method according to claim 1 , which comprises using a magnitude of a vectorial difference as the differential variable.
4 . The method according to claim 1 , which comprises time-delaying a determination of the modified network parameters if the differential variable continuously exceeds the predetermined threshold value over a predetermined period of time.
5 . The method according to claim 1 , wherein the reference network parameters and/or the modified network parameters comprise at least one inductance of the arc suppression coil and at least one line capacitance.
6 . A device for monitoring a three-phase network for a tuning change of an arc suppression coil, the device comprising:
a measuring device for ascertaining a displacement voltage and a network frequency;
a computing device connected to said measuring device for determining reference network parameters and modified network parameters; and
wherein the device is configured to carry out the method according to claim 1 .