US 12,650,484 B2Granted

System and method for calibration of energy meters using phase angle corrections

AssigneeAccuenergy (Canada) Inc.

InventorsYufan Wang, Shaohang Cui, Ketao Li, Liang Wang

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Abstract

This invention relates to a system and method for calibrating energy meters, designed to enhance the accuracy of electrical power measurements. The system incorporates a computing device with specialized calibration software, interfaced with multiple energy meters via a network switch. Each energy meter is equipped with a CPU and DSP, facilitating precise phase angle measurements. A configurable three-phase reference source, connected via power cables, supplies standard calibration signals to the meters. The DSP measures phase angles based on calibration commands triggered by control signals received by the CPU. These measurements are then transmitted to the computing device, which calculates necessary offset corrections. The corrections are subsequently communicated back to the CPU for adjustment of the energy meters' analog-to-digital converter settings, thereby ensuring the meters' outputs are accurately aligned with calibrated standards. This system provides a robust framework for reliable, high-precision energy meter calibration.

Claims8

Dependent claims

A system for calibrating energy meters comprising:

a computing device equipped with calibration software stored on a non-transitory computer-readable medium for managing calibration activities and interfacing with multiple energy meters, wherein each energy meter includes a central processing unit (CPU) and a digital signal processor (DSP);
a network switch connected to the computing device via an Ethernet cable, facilitating communication with the energy meters;
a reference source connected to each of the energy meters via a power cable, capable of delivering a three-phase power output that is configurable through the computing device;
wherein the DSP is configured to measure phase angles for each measurement channel in response to a calibration command, triggered after the CPU receives a predefined control signal from the computing device;
wherein the measured phase angles are transmitted to the computing device through the CPU via the network switch;
wherein the computing device computes an offset correction for each measurement channel based on the received measured phase angles, the offset correction being computed by;
calculating average phase angles for each measurement channel, determining phase angle errors by comparing each calculated average phase angle to an expected value, identifying a maximum phase angle error among all measurement channels, and computing the offset correction using the maximum phase angle error and a phase reference constant, the offset correction being computed by;
calculating average phase angles for each measurement channel, determining phase angle errors by comparing each calculated average phase angle to an expected value, identifying a maximum phase angle error among all measurement channels, and computing the offset correction using the maximum phase angle error and a phase reference constant;
wherein the computed offset corrections are sent back to the CPU for adjusting the settings of an analog-to-digital converter within the energy meters to align measurement accuracy with calibrated standards.

6 more elements

A method for calibrating energy meters using a computing device interfaced with a plurality of energy meters through a network switch, each energy meter including a central processing unit (CPU), a digital signal processor (DSP), and an analog-to-digital converter, and a reference source connected to each energy meter and delivering a three-phase power output, the method comprising:

configuring, by the computing device, the reference source to deliver the three-phase power output at specified voltage, current, power factor, and frequency parameters transmitting, by the computing device, a calibration command to each energy meter via the network switch, causing the CPU of each energy meter to instruct the DSP to measure phase angles for each measurement channel from the three-phase power output received from the reference source:
receiving, by the computing device from each energy meter via the network switch, the measured phase angles for each measurement channel;
calculating average phase angles for each measurement channel using the formula:
θ
i
¯
=
∑
k
=
1
N
⁢
θ
ik
N
(
1
)
wherein θi represents the average phase angle for the i-th measurement channel, θik represents the k-th measured angle in the i-th measurement channel, and N is the total number of accumulated measurements;
determining phase angle errors by comparing each calculated average phase angle to its expected value using the formula:
ϵ
i
=
θ
i
¯
-
θ
expected
,
i
(
2
)
identifying the maximum phase angle error Emax among all measurement channels using the formula:
ϵ
max
=
max
⁢
(
❘
"\[LeftBracketingBar]"
ϵ
i
❘
"\[RightBracketingBar]"
)
(
3
)
computing offset corrections for each measurement channel to adjust analog-to-digital converter settings in the energy meters using the formula:
Δ
i
=
⌈
C
-
❘
"\[LeftBracketingBar]"
ϵ
i
-
ϵ
max
K
❘
"\[RightBracketingBar]"
⌉
(
4
)
wherein Δi is the offset correction for the i-th measurement channel;
C is a predefined constant, and K is a phase reference constant;
and transmitting, by the computing device, the computed offset corrections to the CPU of each energy meter for storage in non-volatile memory and for configuring offset registers of the analog-to-digital converter within each energy meter, thereby aligning measurement accuracy of each energy meter with calibrated standards.

73 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/669,650Filed 21 May 2024
Published: US 2025/0362368 A127 Nov 2025
Granted: 9 Jun 2026
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G01R 35/005
Testing or calibrating of apparatus covered by the other groups of this subclass: calibrating; Standards or reference devices, e.g. voltage or…
G01R 22/10
By electronic methods: using digital techniques
G01R 25/00
Arrangements for measuring phase angle between a voltage and a current or
G01R 35/04
Testing or calibrating of apparatus covered by the other groups of this subclass: of instruments for measuring time integral of power or current