Revenue meter with power quality features
DCFirst Claim
1. An energy meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:
- a sensor coupled with said electric circuit and operative to sense the voltage in said electric circuit and generate an analog signal indicative of said voltage;
an analog to digital converter coupled with said sensor and operative to convert said analog signal to one or more digital samples;
a memory coupled with said analog to digital converter and operative to receive and store said digital samples; and
a detector coupled with said memory and operative to compute a plurality of rolling voltages from said stored digital samples over an interval and to compare each of said plurality of rolling voltages to a threshold and indicate a sag/swell event when said rolling voltage deviates from said threshold.
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Abstract
Power quality detection, monitoring, reporting, recording and communication in a revenue accuracy electrical power meter is disclosed. Transient events are detected by monitoring the wave shape of the electrical power and comparing deviations to a known threshold. Sags and Swells are detected by computing root mean square value over a rolling window and comparing the computed value with a known threshold. Harmonic frequencies and symmetrical components are quantified by a known algorithm and compared with a known threshold. Incoming waveforms are stored to memory. All recorded and computed data is moved to non-volatile storage via direct memory access transfer in the event that a power quality event jeopardizes the operating power of the meter. Further, the meter provides a power supply utilizing high and low capacitive storage banks to supply sufficient energy to survive short duration power quality events which jeopardize the meter'"'"'s operating power.
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Citations
84 Claims
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1. An energy meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:
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a sensor coupled with said electric circuit and operative to sense the voltage in said electric circuit and generate an analog signal indicative of said voltage;
an analog to digital converter coupled with said sensor and operative to convert said analog signal to one or more digital samples;
a memory coupled with said analog to digital converter and operative to receive and store said digital samples; and
a detector coupled with said memory and operative to compute a plurality of rolling voltages from said stored digital samples over an interval and to compare each of said plurality of rolling voltages to a threshold and indicate a sag/swell event when said rolling voltage deviates from said threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An energy meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:
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a draw-out chassis coupled with said meter and operative to fit within a switchboard enclosure;
terminals disposed on said chassis for engaging matching terminals within said enclosure;
a display;
a meter cover operative to enclose said meter and said display within said enclosure;
a seal connected with said meter cover and operative to prevent removal of said meter cover and indicate tampering with said meter;
a sensor coupled with said electric circuit and operative to sense the voltage in said electric circuit and generate an analog signal indicative of said voltage;
an analog to digital converter coupled with said sensor and operative to convert said analog signal to one or more digital samples;
a memory coupled with said analog to digital converter and operative to receive and store said digital samples; and
a detector coupled with said memory and operative to compute a plurality of rolling voltages from said stored digital samples over an interval and to compare each of said plurality of rolling voltages to a threshold and indicate a sag/swell event when said rolling voltage deviates from said threshold.
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18. In an energy meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, a method for detecting sag/swell events comprising:
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sensing the voltage in said electric circuit and producing an analog signal indicative thereof;
converting said analog signal to a plurality of digital samples;
computing a rolling voltage from said plurality of digital samples each time a new digital sample is converted;
comparing said rolling voltage to a threshold value;
indicating a swell event when said rolling voltage exceeds said threshold value; and
indicating a sag event when said rolling voltage is less than said threshold. - View Dependent Claims (19, 20, 21)
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22. An energy meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:
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a sensor coupled with said electric circuit and operative to sense a power parameter in said electric circuit and generate an analog signal indicative of said power parameter;
an analog to digital converter coupled with said sensor and operative to convert said analog signal to one or more digital samples;
a first memory coupled with said analog to digital converter and operative to receive and store said one or more digital samples;
a first processor coupled with said analog to digital converter and further coupled with said first memory by a first data bus;
a second processor coupled with a second memory by a second data bus;
a bus arbiter responsive to said first and second processors and coupled with said first and second data busses, said bus arbiter operative to isolate said first data bus from said second data bus under normal operating conditions; and
said bus arbiter further operative to couple said first data bus to said second data bus and perform a data transfer between said first memory and said second memory. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30)
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31. A revenue meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:
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a draw-out chassis coupled with said meter and operative to fit within a switchboard enclosure;
terminals disposed on said chassis for engaging matching terminals within said enclosure;
a display;
a meter cover operative to enclose said meter and said display within said enclosure;
a seal connected with said meter cover and operative to prevent removal of said meter cover and indicate tampering with said meter;
a first sensor coupled with said electric circuit and operative to sense the voltage in said electric circuit and generate a first analog signal indicative of said voltage;
a second sensor coupled with said electric circuit and operative to sense the current in said electric circuit and generate a second analog signal indicative of said current;
an analog to digital converter coupled with said first and second sensors and operative to convert said first and second analog signals to one or more digital samples;
a memory coupled with said analog to digital converter and operative to receive and store said digital samples; and
a calculator coupled with said memory and operative to compute one or more harmonic frequencies of said voltage and said current from said stored digital samples. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. A revenue meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said electric circuit comprising at least one phase, said meter comprising:
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a draw-out chassis coupled with said meter and operative to fit within a switchboard enclosure;
terminals disposed on said chassis for engaging matching terminals within said enclosure;
a display;
a meter cover operative to enclose said meter and said display within said enclosure;
a seal connected with said meter cover and operative to prevent removal of said meter cover and indicate tampering with said meter;
one or more voltage sensors coupled with each of said at least one phase of said electric circuit and operative to sense the voltage in each of said at least one phase and generate an analog signal indicative of said voltage;
one or more current sensors coupled with each of said at least one phase of said electric circuit and operative to sense the current in each of said at least one phase and generate an analog signal indicative of said current;
at least one analog to digital converter coupled with said one or more voltage sensors and said one or more current sensors and operative to convert said analog signals to one or more digital samples at a rate of at least 64 samples per cycle;
a memory coupled with said analog to digital converter and operative to receive and store said one or more digital samples; and
a processor coupled with said memory and operative to compute one or more fundamental voltage vectors from the magnitude and phase angle of the fundamental frequency of each of said voltage and said current and further operative to compute the zero, positive and negative sequence voltages by performing a vector addition of said one or more fundamental voltage vectors. - View Dependent Claims (44, 45, 46, 47, 48, 49)
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50. In a revenue meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said electric circuit comprising at least one phase, a method of computing symmetrical components comprising:
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providing a switchboard revenue meter including a draw-out chassis coupled with said meter and operative to fit within a switchboard enclosure, terminals disposed on said chassis for engaging matching terminals within said enclosure, a display, a meter cover operative to enclose said meter and said display within said enclosure and a seal connected with said meter cover and operative to prevent removal of said meter cover and indicate tampering with said meter;
sensing the voltages in each of said at least one phase and generating analog signals indicative thereof;
converting said analog signals to one or more digital samples at a rate of at least 64 samples per cycle;
storing said digital samples in a memory;
computing one or more fundamental voltage vectors from the magnitude and angle of the fundamental frequency of each of the sensed voltages from said stored digital samples; and
performing a vector addition of said one or more fundamental voltage vectors to compute the zero sequence voltage. - View Dependent Claims (51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61)
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62. A revenue meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:
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a draw-out chassis coupled with said meter and operative to fit within a switchboard enclosure;
terminals disposed on said chassis for engaging matching terminals within said enclosure;
a display;
a meter cover operative to enclose said meter and said display within said enclosure;
a seal connected with said meter cover and operative to prevent removal of said meter cover and indicate tampering with said meter;
a sensor coupled with said electric circuit and operative to sense a power parameter in said electric circuit and generate an analog signal indicative of said power parameter;
an analog to digital converter coupled with said sensor and operative to convert said analog signal to one or more digital samples at a rate of at least 64 samples per cycle;
a first memory coupled with said analog to digital converter and operative to receive and store said one or more digital samples;
a second memory coupled with said first memory;
a power quality event detector coupled with said analog to digital converter and operative to detect a power quality event and generate a trigger signal;
a holdoff timer coupled with said detector and operative to receive, delay and re-transmit said trigger signal; and
a memory preservation mechanism coupled with said first memory, said second memory and said holdoff timer and operative to preserve the contents of said first memory using said second memory upon receipt of said trigger signal from said holdoff timer. - View Dependent Claims (63, 64, 65, 66, 67, 68, 69, 70)
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71. A revenue meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:
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a draw-out chassis coupled with said meter and operative to fit within a switchboard enclosure;
terminals disposed on said chassis for engaging matching terminals within said enclosure;
a display;
a meter cover operative to enclose said meter and said display within said enclosure;
a seal connected with said meter cover and operative to prevent removal of said meter cover and indicate tampering with said meter;
a first power supply coupled with said electric circuit and operative to provide power to said meter from said electric circuit under normal operating conditions; and
a second power supply operative to provide power to said meter when a power quality event occurs on said electric circuit, said second power supply including;
at least one first capacitor coupled with said electric circuit and operative to store electrical energy from said electric circuit; and
at least one second capacitor coupled with said at least one first capacitor and said meter and operative to store electrical energy from said electric circuit;
said first and second capacitors further operative to provide said energy to said meter when said power quality event occurs. - View Dependent Claims (72)
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73. A revenue meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:
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a draw-out chassis coupled with said meter and operative to fit within a switchboard enclosure;
terminals disposed on said chassis for engaging matching terminals within said enclosure;
a display;
a meter cover operative to enclose said meter and said display within said enclosure;
a seal connected with said meter cover and operative to prevent removal of said meter cover and indicate tampering with said meter;
a switching regulator coupled with said electric circuit and said meter and operative to convert said high voltage electrical energy to low voltage electrical energy; and
a power supply coupled between said electric circuit and said switching regulator and operative to store said high voltage electrical energy and provide power to said meter when a power quality event occurs on said electric circuit. - View Dependent Claims (74)
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75. A revenue meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:
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a draw-out chassis coupled with said meter and operative to fit within a switchboard enclosure;
terminals disposed on said chassis for engaging matching terminals within said enclosure;
a display;
a meter cover operative to enclose said meter and said display within said enclosure;
a seal connected with said meter cover and operative to prevent removal of said meter cover and indicate tampering with said meter; and
a power supply coupled with said electric circuit and said meter and operative to store energy from said electric circuit and provide said energy to said meter when a power quality event occurs on said electric circuit, said power supply including;
a high voltage portion coupled with said electric circuit and a low voltage portion coupled with said high voltage portion and said meter; and
a processor coupled with said high voltage portion and operative to monitor said power supply and signal said meter when said stored power runs low. - View Dependent Claims (76)
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77. A revenue meter for measuring the delivery of electrical energy from an energy supplier to a consumer through an electric circuit, said meter comprising:
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a draw-out chassis coupled with said meter and operative to fit within a switchboard enclosure;
terminals disposed on said chassis for engaging matching terminals within said enclosure;
a display;
a meter cover operative to enclose said meter and said display within said enclosure;
a seal connected with said meter cover and operative to prevent removal of said meter cover and indicate tampering with said meter; and
a power supply coupled with said electric circuit and said meter and operative to store energy from said electric circuit and provide said energy to said meter when a power quality event occurs on said electric circuit, said power supply including;
a rectification circuit coupled with said electric circuit and operative to receive AC electric energy from said electric circuit and convert said AC electric energy to high voltage DC electric energy;
a charge control circuit coupled with said rectification circuit;
a first energy store coupled with said charge control circuit and operative to receive and store said high voltage DC electric energy from said rectification circuit at a rate controlled by said charge control circuit, said first energy store further operative to provide said stored high voltage DC electric energy to said meter when a power quality event occurs on said electric circuit; and
a switching regulator coupled with said rectification circuit and said first energy store, said switching regulator operative to receive said high voltage DC electric energy from said rectification circuit and said first energy store, said switching regulator further operative to covert said high voltage DC electric energy to low voltage DC electric energy and provide said low voltage DC electric energy to said meter. - View Dependent Claims (78, 79, 80, 81, 82, 83, 84)
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Specification