Directional harmonic overcurrent relay device

A single or multiple phase directional harmonic overcurrent relay device for monitoring currents at one or more harmonic frequencies in an electric power system comprising:

• a current input means for allowing current from the power system being monitored to enter said relay device and for channeling a signal proportional to said current to a harmonic current filter;
• a current input overrange detector capable of receiving a signal from said current input means and capable of transmitting an inhibit signal to a harmonic time-overcurrent generation means when the signal received from the current input means corresponds to a condition of current overrange;
• a polarizing voltage input means for allowing polarizing voltage from the power system being monitored to enter said relay device and for channeling a signal proportional to said polarizing voltage to a harmonic voltage filter;
• at least one harmonic current filter capable of receiving a signal from said current input means and capable of channelling a signal proportional only to the particular harmonic frequency being monitored to a phase detection means and a minimum current pickup means;
• at least one harmonic voltage filter capable of receiving a signal from said polarizing voltage input means and capable of channeling a signal proportional only to the particular harmonic frequency monitored to a polarizing voltage level detection means and a phase detection means:
• a harmonic polarizing voltage level detector capable of receiving signals from at least one harmonic voltage filter and capable of transmitting a control signal to a harmonic time-overcurrent generation means;
• harmonic current minimum pickup means capable of receiving signals from said harmonic current filters and capable of transmitting a signal proportional to the magnitude of the harmonic current to a harmonic time-overcurrent generation means;
• harmonic phase detection means capable of receiving signals from said harmonic current and voltage filters and capable of transmitting a signal to a harmonic time-overcurrent generation means when the phase angle between the harmonic current and polarizing voltage falls within a given set of values;
• harmonic time-overcurrent generation means capable of receiving signals from said harmonic polarizing voltage level detector, said harmonic phase detection means, said current input overrange detector, and said harmonic current minimum pickup means, and capable of signaling a trip means when a condition of overcurrent is sensed for a given duration of time;
• and
• a trip means capable of receiving signals from the harmonic time-overcurrent generation means, and capable of signaling an appropriate external protective or diagnostic device when a condition of overcurrent is present.