Partial discharge determination method, partial discharge determination apparatus, and partial discharge determination system for power device, and method for manufacturing power device including the partial discharge determination method

A partial discharge determination apparatus for a power device, the partial discharge determination apparatus comprising:

• a low-pass filter configured to receive an acoustic signal and remove an electromagnetic noise superimposed on the acoustic signal, the acoustic signal being resulting from application of an impulse voltage to a device under test;
• a mechanical oscillation removal unit configured to remove a mechanical oscillation component of the device under test, from the acoustic signal resulting from application of the impulse voltage which is a high voltage, based on the mechanical oscillation component acquired in advance and included in the acoustic signal resulting from application of the impulse voltage which is a low voltage causing no partial discharge;
• a partial discharge determination unit configured to determine whether partial discharge is caused in the device under test, based on the acoustic signal resulting from application of the high voltage, the mechanical oscillation component being removed from the acoustic signal;
• and
• a margin determination unit configured to determine, when the partial discharge is caused, a margin before dielectric breakdown of the device under test, by determining a feature amount of partial discharge based on a correlation, acquired in advance, between a feature amount of a partial discharge signal obtained as an acoustic signal and the feature amount of partial discharge.

A partial discharge determination system for a power device, the partial discharge determination system comprising:

• an impulse voltage generator configured to apply an impulse voltage to a device under test;
• an acoustic emission sensor installed on a wall surface of a casing which houses the device under test;
• a low-pass filter configured to receive an acoustic signal and remove an electromagnetic noise superimposed on the acoustic signal, the acoustic signal being resulting from application of the impulse voltage, the acoustic signal being acquired by the acoustic emission sensor;
• a mechanical oscillation removal unit configured to remove a mechanical oscillation component of the device under test, from the acoustic signal resulting from application of the impulse voltage which is a high voltage, based on the mechanical oscillation component acquired in advance and included in the acoustic signal resulting from application of the impulse voltage which is a low voltage causing no partial discharge;
• a partial discharge determination unit configured to determine whether partial discharge is caused in the device under test, based on the acoustic signal resulting from application of the high voltage, the mechanical oscillation component being removed from the acoustic signal;
• and
• a margin determination unit configured to determine, when the partial discharge is caused, a margin before dielectric breakdown of the device under test, by determining a feature amount of partial discharge based on a correlation, acquired in advance, between a feature amount of a partial discharge signal obtained as an acoustic signal and the feature amount of partial discharge.