Total Harmonic Distortion Measurement For Energy ... Harmonic Distortion Measurement For Energy ... is supported for net metering systems with ... Total Harmonic Distortion Measurement For Energy Monitoring

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  • Load

    Phase A Phas

    e C

    Phase B

    Neu

    tral

    +

    -

    Sx, COMx

    MSP430F67791A

    R33

    32768 Hz

    XIN

    XOUT

    GPIOs

    TOTAL

    AB

    kWh

    LCDCAP

    PULSE LEDs

    UART 9600 bpsUART RX

    UART TX

    6' Modulator

    6' Modulator

    -

    Source From Utility

    CT

    Phase APh

    ase

    B

    Phase C

    6' Modulator

    6' Modulator

    6' Modulator

    +

    +

    -

    +

    -

    +

    -

    +

    -

    RSTVCC

    VSS

    6' Modulator

    +

    -

    +

    -

    6' Modulator

    24

    Vref

    IA

    IB

    IC

    VA

    VB

    VN

    VN

    VC

    VN

    IN

    Neu

    tral

    CT

    CT

    CT

    Capacitive Power supply(TPS54060)

    1TIDUB70AJanuary 2016Revised March 2016Submit Documentation Feedback

    Copyright 2016, Texas Instruments Incorporated

    Total Harmonic Distortion Measurement For Energy Monitoring

    TI DesignsTotal Harmonic Distortion Measurement For EnergyMonitoring

    All trademarks are the property of their respective owners.

    TI DesignsThis reference design implements power qualityanalysis in a three-phase energy measurementsystem. Power quality monitoring and analysis has anincreasingly large role in improving the reliability of theelectricity grid. The design measures total harmonicdistortion (THD), monitors voltage sags and swells,and measures phase-to-phase angles to helpdetermine phase sequence and prevent accidentalphase swapping. Four-quadrant energy measurementis supported for net metering systems with bi-directional energy flow.

    Design Resources

    TIDM-THDREADING Design FolderMSP430F67791A Product FolderTPS54060 Product FolderEVM4340-F6779 Tool Folder

    ASK Our E2E Experts

    Design Features THD Calculated for Voltage and Current Voltage Sag and Swell Events Logged With

    Programmable Threshold Levels Phase-to-Phase Angle Measurement Four-Quadrant Energy Measurement With Class

    0.2 Accuracy Complete Energy Library With Fundamental

    Voltage and Current, Fundamental Active andReactive Power, Active and Reactive Energy, RootMean Square (RMS) Current and Voltage, PowerFactor, and Line Frequency

    Featured Applications Metering Street Lighting

    http://www.go-dsp.com/forms/techdoc/doc_feedback.htm?litnum=TIDUB70Ahttp://www.ti.com/tool/TIDM-THDREADINGhttp://www.ti.com/product/MSP430F67791Ahttp://www.ti.com/product/TPS54060http://www.ti.com/tool/EVM4340-F6779http://e2e.ti.comhttp://e2e.ti.com/support/applications/ti_designs/

  • System Description www.ti.com

    2 TIDUB70AJanuary 2016Revised March 2016Submit Documentation Feedback

    Copyright 2016, Texas Instruments Incorporated

    Total Harmonic Distortion Measurement For Energy Monitoring

    An IMPORTANT NOTICE at the end of this TI reference design addresses authorized use, intellectual property matters and otherimportant disclaimers and information.

    1 System DescriptionThe presence of harmonics can have a negative impact on both consumer loads and the electricity grid.This design implements a Class 0.2 three-phase energy measurement system that measures the totalharmonic distortion, which can ensure that the current drawn by a customer's load does not significantlydegrade the voltage delivered from the utility to other customers. For additional power quality informationon the supply, voltage sags and swells are also logged. In addition, this design measures phase-to-phaseangles, which can help in determining phase sequence and prevent accidentally swapping phases wheninstalling an energy measurement system. This design supports four quadrant energy measurement forlogging energy consumption and generation in systems that could both provide electricity to the utilitycompany or consume the energy generated from the utility companies.

    This design guide has a complete metrology source code provided as a downloadable zip file.

    1.1 MSP430F67791AFor sensing and calculating the metrology parameters, the MSP430F67791A e-meter SoC is used. Thisdevice is the latest metering system on chip (SoC) that belongs to the MSP430F67xxA family of devices.In regards to metrology, the MSP430F67791A energy library software has support for calculation ofvarious parameters for up to three-phase energy measurement. The key parameters calculated duringenergy measurements are: RMS current and voltage, fundamental current and voltage, current andvoltage THD, phase-to-phase angles, active and reactive power and energies, power factor, andfrequency.

    1.2 TPS54060The TPS54060 is used in the power supply to help provide a 3.3-V output from an input mains voltage of120/230-VRMS AC at 50 or 60 Hz. Figure 5 shows how the TPS54060 is used to create the 3.3-V outputfrom the 120/230-VRMS AC input.

    http://www.ti.comhttp://www.go-dsp.com/forms/techdoc/doc_feedback.htm?litnum=TIDUB70A

  • Load

    Phase A Phas

    e C

    Phase BN

    eutr

    al+

    -

    Sx, COMx

    MSP430F67791A

    R33

    32768 Hz

    XIN

    XOUT

    GPIOs

    TOTAL

    AB

    kWh

    LCDCAP

    PULSE LEDs

    UART 9600 bpsUART RX

    UART TX

    6' Modulator

    6' Modulator

    -

    Source From Utility

    CT

    Phase APh

    ase

    B

    Phase C

    6' Modulator

    6' Modulator

    6' Modulator

    +

    +

    -

    +

    -

    +

    -

    +

    -

    RSTVCC

    VSS

    6' Modulator

    +

    -

    +

    -

    6' Modulator

    24

    Vref

    IA

    IB

    IC

    VA

    VB

    VN

    VN

    VC

    VN

    IN

    Neu

    tral

    CT

    CT

    CT

    Capacitive Power supply(TPS54060)

    www.ti.com Block Diagram

    3TIDUB70AJanuary 2016Revised March 2016Submit Documentation Feedback

    Copyright 2016, Texas Instruments Incorporated

    Total Harmonic Distortion Measurement For Energy Monitoring

    2 Block Diagram

    Figure 1. System Block Diagram

    Figure 1 shows the high-level interface used for a three-phase energy measurement application that usesthe MSP430F67791A. A three-phase four-wire star connection to the AC mains is shown in this case.Current sensors are connected to each of the current channels, and a simple voltage divider is used forcorresponding voltages. The CT has an associated burden resistor that has to be connected at all times toprotect the measuring device. The choice of the CT and the burden resistor is done based on themanufacturer and current range required for energy measurements. The CTs can be easily replaced byRogowski coils with minimal changes to the front-end. The choice of voltage divider resistors for thevoltage channel is selected to ensure the mains voltage is divided down to adhere to the normal inputranges that are valid for the MSP43024. Refer to the MSP4305xx/6xx users guide (SLAU208) anddevice specific datasheet (SLAS983) for these numbers.

    http://www.ti.comhttp://www.go-dsp.com/forms/techdoc/doc_feedback.htm?litnum=TIDUB70Ahttp://www.ti.com/lit/pdf/SLAU208http://www.ti.com/lit/pdf/SLAS983

  • UnifiedClock

    System

    512KB256KB128KB

    Flash

    MCLK

    ACLK

    SMCLK

    CPUXV2and

    WorkingRegisters(25 MHz)

    EEM(S: 8+2)

    XIN XOUT

    JTAG,SBW

    Interface

    Port PJ

    eUSCI_A0eUSCI_A1eUSCI_A2eUSCI_A3

    (UART,IrDA,SPI)

    SD24_B

    7 Channel6 Channel4 Channel

    ADC10_A

    10 Bit200 KSPS

    LCD_C

    8MUXUp to 320Segments

    REF

    Reference1.5 V, 2.0 V,

    2.5 V

    DVCC DVSS AVCC AVSS PA

    I/O PortsP1, P2

    28 I/OsInterrupt,Wakeup

    PA116 I/Os

    P1.x P2.xRST/NMI

    32KB16KB

    RAM

    PJ.x

    DMA

    3 Channel

    PMMAuxiliarySupplies

    LDOSVM, SVS

    BOR

    MPY32

    SYS

    Watchdog

    PortMapping

    Controller

    CRC16

    PD

    I/O PortsP7, P8

    28 I/Os

    PD116 I/Os

    I/O PortsP9, P1028 I/O

    PE116 I/O

    P7.x P8.x

    PC

    I/O PortsP5, P6

    28 I/Os

    PC116 I/Os

    P5.x P6.x

    PB

    I/O PortsP3, P4

    28 I/Os

    PB116 I/Os

    P3.x P4.x

    eUSCI_B0eUSCI_B1

    (SPI, I C)2

    RTC_CE

    (32 kHz)

    AUX1 AUX2 AUX3

    TA1TA2TA3

    Timer_A2 CC

    Registers

    Ta0

    Timer_A3 CC

    Registers

    COMP_B(ExternalVoltage

    Monitoring)

    I/O PortsP11

    16 I/O

    PF16 I/O

    PF

    P9.x P10.x

    PE

    P11.x

    Block Diagram www.ti.com

    4 TIDUB70AJanuary 2016Revised March 2016Submit Documentation Feedback

    Copyright 2016, Texas Instruments Incorporated

    Total Harmonic Distortion Measurement For Energy Monitoring

    2.1 Highlighted Products

    2.1.1 MSP430F67791AThe MSP430F67791A belongs to the powerful 16-bit MSP430F6xx platform. This device finds itsapplication in energy measurement and has the necessary architecture to support it. TheMSP430F67791A has a powerful 25-MHz CPU with MSP430CPUx architecture. The analog front-end(AFE) consists of seven independent 24-bit analog-to-digital converters (ADC) based on a secondorder sigma-delta architecture that supports differential inputs. The sigma-delta ADCs (24_B) operateindependently and are capable of 24-bit results. They can be grouped together for simultaneous samplingof voltages and currents on the same trigger. In addition, it also has an integrated gain stage to supportgains up to 128 for amplification of low-output current sensors. A 3232-bit hardware multiplier on this chipcan be used to further accelerate math intensive operations during energy computation.

    For more info on the features of the MSP430F67791A, a block diagram of the chip is shown in Figure 2.

    Figure 2. MSP430F67791A Block Diagram

    2.1.2 T

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