Distribution automation smart remote terminal unit

An improved distribution automation remote terminal unit for connection to a plurality of potential sensors and to a plurality of current sensors, said plurality of potential sensors being connected to an AC distribution feeder for sensing the AC potentials in the three phase lines of said distribution feeder, said plurality of current sensors being connected to said distribution feeder for sensing the AC currents in said lines, said improved distribution automation remote terminal unit being in communication with a remotely located master station, said improved distribution automation remote termination unit comprising:

• first means directly connected to each of said plurality of potential sensors for producing a potential signal of reduced peak-to-peak voltage corresponding in phase to only the AC potential waveform on each phase of said lines of said distribution feeder,
• second means directly connected to each of said plurality of current sensors for producing a current signal of reduced peak-to-peak voltage corresponding in phase to only the AC current waveform on each phase of said lines of said distribution feeder,
• means receptive of said potential and current signals from said first and second producing means for sampling the voltage of said potential and current signals a plurality of times for each cycle to produce a digital value for each sampled voltage,
• means receptive of each said digital value from said converting means for processing waveform parameters of at least peak positive and negative signal values, zero crossing times, and RMS for each cycle for said plurality of sensed AC potentials and currents in said distribution feeder, said processing means further determining summary information on the signal states on said distribution feeder as sensed by said plurality of current and potential sensors,
• means receptive of said summary information for extending said information to said master station.

An improved distribution automation remote terminal unit (DA/RTU) for connection to a plurality of potential sensors (PT) and to a plurality of current sensors (CT), said plurality of potential sensors being connected to an AC distribution feeder (30) for sensing the AC potentials in the lines of said distribution feeder, said plurality of current sensors being connected to said distribution feeder for sensing the AC currents in said lines, said improved distribution automation remote termination unit comprising:

• first means (T1, 320) directly connected to each of said plurality of potential sensors for producing a potential signal of reduced peak-to-peak voltage correspond in phase to only the AC potential waveform on each phase of said lines of said distribution feeder,
• second means (T2, 320) directly connected to each of said plurality of current sensors for producing a current signal of reduced peak-to-peak voltage corresponding in phase to only the AC current waveform on each phase of said lines of said distribution feeder.
• means (330) receptive of said potential and current signals from said first and second producing means for sampling the voltage of said potential and current signals a plurality of times for each cycle,
• means (340, 342) receptive of said sampled voltage signals from said sampling means for converting each said sampled voltage to a digital value,
• means (360, 362) receptive of each said digital value from said converting means for processing waveform parameters of at least peak positive and negative signal values, zero crossing times, and RMS for each cycle for said plurality of sensed AC potentials and currents in said distribution feeder,
• means (380) connected to said determining means for storing said waveform parameters, and
• means (370, 372) connected to said storing means and receptive of said waveform parameters for determining selected information on the signal states on said distribution feeder.

An improved distribution automation remote terminal unit for connection to a plurality of potential sensors and to a plurality of current sensors, said plurality of potential sensors being connected to an AC distribution feeder for sensing the AC potentials in the lines of said distribution feeder, said plurality of current sensors being connected to said distribution feeder for sensing the AC currents in said lines, said improved distribution automation remote termination unit comprising:

• first means plurality of potential sensors for producing a potential signal of reduced peak-to-peak voltage corresponding in phase to only the AC potential waveform on said distribution feeder,
• second means directly connected to each of said plurality of current sensors for producing a current signal of reduced peak-to-peak voltage corresponding in phase to only the AC current waveform on said distribution feeder,
• means receptive of said potential and current signals from said first and second producing means for sampling the voltage of said potential and current signals a predetermined number of times per cycle.
• means receptive of said sampled voltage signals from said sampling means for converting each said sampled voltage to a digital value,
• means receptive of each said digital value from said converting means for processing waveform parameters of at least peak positive and negative signal values, zero crossing times, and RMS for each cycle for said plurality of sensed AC potentials and currents in said distribution feeder.
• means connected to said determining means for storing said waveform parameters, and
• means connected to said storing means and receptive of said waveform parameters for determining selected information on the signal states on said distribution feeder, wherein said processing means further calculates the crest factor for each cycle, said storing means further stores said crest factor for each cycle, and said determining means generates error information in the event that the crest factor for a given cycle varies by more than a predetermined range about 1.414 and when the corresponding overcurrent and overvoltage parameter is absent, said error information being indicative of a failure in the operation of said potential and current sensors and of said first and second producing means.

An improved distribution automation remote terminal unit( DA/RTU) for connection to a plurality of potential transformers (PT) and to a plurality of current transformers (CT), said plurality of potential transformers being connected to an AC distribution feeder (30) for sensing the AC potentials in the lines of said distribution feeder, said plurality of current transformers being connected to said distribution feeder for sensing the AC currents in said lines, said improved distribution automation remote termination unit comprising:

• first means (T1, 320) directly connected to each of said plurality of potential transformers for producing a potential signal of reduced peak-to-peak voltage corresponding in phase to only the AC potential waveform on said distribution feeder,
• second means (T2, 320) directly connected to each of said plurality of current transformers for producing a current signal of reduced peak-to-peak voltage corresponding in phase to only the AC current waveform on said distribution feeder,
• means (330) receptive of said potential and current signals from said first and second producing means for sampling the voltage of said potential and current signals a predetermined number of times per cycle,
• means (340, 342) receptive of said sampled voltage signals from said sampling means for converting each said sampled voltage to a digital value,
• means (360, 362) receptive of each said digital value from said converting means for processing waveform parameters of at lest peak positive and negative signal values, zero crossing times, and RMS for each cycle for said plurality of sensed AC potentials and currents in said distribution feeder,
• means (380) connected to said determining means for storing said calculated waveform parameters,
• means (370, 372) connected to said storing means and receptive of said calculated waveform parameters for determining information on the signal states of said distribution feeder, said signal states including at least said waveform parameters, backfeed information when the calculated phase angle indicates a reversal of current, overcurrent information when the calculated RMS or peak value for a given current cycle exceeds a predetermined current value, and overpotential information when the calculated RMS or peak value for a given AC potential exceeds a predetermined potential value.

An improved distribution automation remote terminal unit (DA/RTU) for connection to a plurality of potential sensors and to a plurality of current sensors (CT), said plurality of potential sensors being connected to an AC distribution feeder (30) for sensing the AC potentials in the three phase lines of said distribution feeder, said plurality of current sensors being connected to said distribution feeder for sensing the AC currents in said lines, upstream and downstream devices being connected on said distribution feeder, said improved distribution automation remote termination unit comprising:

• first means (T1, 320) directly connected to each of said plurality of potential sensors for producing a potential signal of reduced peak-to-peak voltage corresponding in phase to only the AC potential waveform on each phase of said lines of said distribution feeder,
• second means (T2 320) directly connected to each of said plurality of current sensors for producing a current signal of reduced peak-to-peak voltage corresponding in phase to only the AC current waveform on each phase of said lines of said distribution feeder,
• means (330) receptive of said potential and current signals from said first and second producing means for sampling the voltage of said potential and current signals a plurality of times for each cycle.
• means (340, 342) receptive of said sampled voltage signals from said sampling means for converting each said sampled voltage to a digital value,
• means (360, 362, 380, 370, 372) receptive of each said digital value from said converting means for determining waveform parameters for each cycle for said plurality of sensed AC potentials and currents in said distribution feeder, said determining means receptive of said waveform parameters for further determining information on the signal states on said distribution feeder, said determining means having selected time intervals for analyzing the states of signals on said distribution feeder, said determining means responsive to said selected time intervals for preprocessing said states of said signals and for producing summary indicators indicating selected conditions of said signal states according to said selected time intervals, said signal states being caused by the operation of said upstream downstream devices on said distribution feeder.

An improved distribution automation/remote terminal unit (DA/RTU) for connection to a plurality of potential sensors and to a plurality of current sensors, said plurality of potential sensors being connected ot an AC distribution feeder (30) for sensing the AC potentials in the three phase lines of said distribution feeder, said plurality of current sensors being connected to said distribution feeder for sensing the AC currents in said lines, upstream and downstream devices located on said distribution feeder, said improved distribution automation remote termination unit comprising:

• first means (T1, 320) directly connected to each of said plurality of potential sensors for producing a potential signal of reduced peak-to-peak voltage corresponding in phase to only the AC potential waveform on each phase of said lines of said distribution feeder,
• second means (T2, 320) directly connected to each of said plurality of current sensors for producing a current signal of reduced peak-to-peak voltage corresponding in phase to only the AC current waveform on each phase of said lines of said distribution feeder,
• means (330, 340, 342) receptive of said potential and current signals from said first and second producing means for sampling the voltage of said potential and current signals a plurality of times for each cycle to produce a digital value for each sampled voltage,
• means (360, 362, 380, 370, 372) receptive of each said digital value from said sampling means for determining waveform parameters for each cycle for said plurality of sensed AC potentials and currents in said distribution feeder, said determining means receptive of said waveform parameters for further determining information on the signal states on said distribution feeder, said determining means having selected time intervals for analyzing the states of signals on said distribution feeder, said determining means being further responsive to said selected time intervals for producing summary indications indicating selected conditions of said signal states according to said selected time intervals, said signal states caused by the operation of said upstream and downstream devices on said distribution feeder.

An improved distribution automation remote terminal unit (DA/RTU) for connection to a plurality of potential sensors and to a plurality of current sensors at a location near said sensors, said plurality of potential sensors being connected to an AC distribution feeder (30) for sensing the AC potentials in the three phase lines of said distribution feeder including neutral, a master station remotely located from said distribution automation remote terminal unit, said plurality of current sensors being connected to said distribution feeder for sensing the AC currents in said lines, said improved distribution automation remote termination unit comprising:

• first means (T1, 320) directly connected to each of said plurality of potential sensors for producing a potential signal of reduced peak-to-peak voltage corresponding in phase to only the AC potential waveform on each phase of said lines of said distribution feeder,
• second (T2, 320) directly connected to each of said plurality of current sensors for producing a current signal of reduced peak-to-peak voltage corresponding in phase to only the AC current waveform on each phase of said lines of said distribution feeder,
• means (330, 340, 342) receptive of said potential and current signals from said first and second producing means for sampling the voltage of said potential and current signals a plurality of times for each cycle to produce a digital value for each sampled voltage,
• means (360, 362, 380, 370, 372) receptive of each said digital value from said sampling means for determining waveform parameters for each cycle for said plurality of sensed AC potentials and currents in said distribution feeder, said determining means receptive of said waveform parameters for further determining information on the signal states on said distribution feeder, said determining means having selected time intervals for analyzing the states of signals on said distribution feeder, said determining means being further responsive to said selected time intervals for producing summary indications indicating selected conditions of said signal states according to said selected time intervals, said signal states caused by at least one or a combination of the following occurring on said distribution feeder:
• magnetization, cold load pick-up, overcurrent, and backfeed,
• means (80) receptive of said summary indications for transmitting said summary indications to said master station.

An improved distribution automation/remote terminal unit (DA/RTU) for connection to a plurality of potential sensors and to a plurality of current sensors at a location near said sensors, said plurality of potential sensors being connected to an AC distribution feeder (30) for sensing the AC potentials in the three phase lines of said distribution feeder, a master station remotely located from said distribution automation remote terminal unit, upstream and downstream devices being connected to said distribution feeder, said plurality of current sensors being connected to said distribution feeder for sensing the AC currents in said lines, said improved distribution automation remote termination unit at said location comprising:

• firt means (T1, 320) directly connected to each of said plurality of potential sensors for producing a potential signal of reduced peak-to-peak voltage corresponding in phase to only the AC potential waveform on each phase of said lines of said distribution feeder,
• second means (T2, 320) directly connected to each of said plurality of current sensors for producing a current signal of reduced peak-to-peak voltage corresponding in phase to only the AC current waveform on each phase of said lines of said distribution feeder,
• means (330, 340, 342) receptive of said potential and current signals from said first and second producing means for sampling the voltage of said potential and current signals a plurality of times for each cycle to produce a digital value for each sampled voltage,
• means (360, 362, 380, 370, 372) receptive of each said digital value from said sampling means for determining waveform parameters for each cycle for said plurality of sensed AC potentials and currents in said distribution feeder, said determining means receptive of said waveform parameters for further determining information on the signal states on said distribution feeder, said determining means receiving time intervals and values from said master station for analyzing the states of signals on said distribution feeder, said determining means being further responsive to said time intervals and values for producing summary indications indicating selected conditions of said signal states according to said time intervals and said values, said signal states caused by the operation of said upstream and downstream devices, magnetization, overcurrent, backfeed, faults occurring alone or together on said distribution feeder.