Frequency estimation and tracking using current

A method of tracking a frequency of an alternating current in an electric power system using a line-mounted sensor, comprising:

• receiving, using a waveform receiving subsystem, a representation of the current waveform;
• sampling, using a sampling subsystem, the representation of the current waveform at a first estimated frequency and generating a sampled representation of the current waveform;
• filtering, using a filter subsystem, the sampled representation of the current waveform and generating a filtered and sampled representation of the current waveform;
• determining, using a period subsystem, a period of the filtered and sampled representation of the current waveform;
• determining, using a frequency determination subsystem, a second estimated frequency based on the period;
• and
• harvesting, using a power subsystem, power from an electrical conductor to which the line-mounted sensor is electrically coupled;
• wherein the sampling subsystem further uses the second estimated frequency in a subsequent iteration to sample a subsequent representation of the current waveform.

A system comprising:

• an intelligent electronic device (IED), comprising:
• a first communication subsystem to receive a sampled representation of the current waveform from a line-mounted current sensor;
• a control action subsystem to generate a control action based on the sampled representation of the current waveform;
• the line-mounted current sensor comprising:
• a waveform receiving subsystem to receive a representation of the current waveform;
• a data sampling subsystem to sample the representation of the current waveform at a first estimated frequency and to generate the sampled representation of the current waveform;
• a filter subsystem to filter the sampled representation of the current waveform and to generate a filtered and sampled representation of the current waveform;
• a period subsystem to determine an estimated period of the filtered and sampled representation of the current waveform;
• a frequency determination subsystem to determine a second estimated frequency based on the estimated period;
• and
• a communication subsystem to transmit the sampled representation of the current waveform to the IED;
• wherein the second estimated frequency is used by the data sampling subsystem in a subsequent iteration to sample a subsequent representation of the current waveform.