High-fidelity voltage measurement using a capacitance-coupled voltage transformer

A system to detect a fault in an electric power delivery system, comprising:

• a capacitance-coupled voltage transformer (CCVT) in electrical communication with the electric power delivery system, the CCVT comprising:
• a tuning reactor;
• a first capacitor electrically coupled between a high-voltage electrical bus and the tuning reactor;
• and
• a second capacitor electrically coupled between the tuning reactor and a ground connection;
• a step-down transformer comprising:
• a primary winding electrically coupled to the tuning reactor;
• and
• a secondary winding electromagnetically coupled to the primary winding;
• a first current measurement device disposed between the second capacitor and the ground connection, the first current measurement device to provide a first electrical signal corresponding to a first current flow through the first capacitor;
• a second current measurement device disposed between the primary winding and the ground connection, the second current measurement device to provide a second electrical signal corresponding to a second current flow through the primary winding;
• a processing system to:
• receive a measurement of a primary current through the high-voltage electrical bus;
• generate a high-fidelity voltage signal based on the first electrical signal and the second electrical signal;
• identify an incident traveling wave and a reflected traveling wave based on the high-fidelity voltage signal and the measurement of the primary current;
• detect a fault based on the incident traveling wave and the reflected traveling wave;
• and
• a protective action module to implement a protective action based on detection of the fault.

A system to detect a fault in an electric power delivery system, comprising:

• a capacitance-coupled voltage transformer (CCVT) in electrical communication with the electric power delivery system, the CCVT comprising:
• a tuning reactor;
• a first capacitor electrically coupled between a high-voltage electrical bus and the tuning reactor;
• and
• a second capacitor electrically coupled between the tuning reactor and a ground connection;
• a step-down transformer, comprising:
• a primary winding electrically coupled to the tuning reactor;
• and
• a secondary winding electromagnetically coupled to the primary winding;
• a first current measurement device comprising a capacitive shunt to measure a first current through the second capacitor;
• a second current measurement device to measure second current through the primary winding;
• an intelligent electronic device (IED) in communication with the first current measurement device, to:
• receive a measurement of a primary current through the high-voltage electrical bus;
• generate a first voltage signal based on the first current;
• generate a second voltage signal based on the second current;
• identify an incident traveling wave and a reflected traveling wave based on the first voltage signal, the second voltage signal, and the measurement of the primary current;
• and
• detect a fault based on the incident traveling wave and the reflected traveling wave;
• and
• a protective action module to implement a protective action based on detection of the fault.

A method of detecting a fault in an electric power delivery system, comprising:

• providing a capacitance-coupled voltage transformer (CCVT) in electrical communication with the electric power delivery system, the CCVT comprising a stack of capacitors and an electrical contact to a first ground connection;
• receiving, from a first current measurement device disposed between the stack of capacitors and the first ground connection, a first electrical signal corresponding to a first current flowing through the CCVT;
• generating a first voltage signal based on the first electrical signal from the first current measurement device;
• identifying an incident traveling wave and a reflected traveling wave based on the first voltage signal;
• detecting a fault based on the incident traveling wave and the reflected traveling wave;
• and
• implementing a protective action based on detection of the fault.