Docstoc

The Energy Bully

Document Sample
The Energy Bully Powered By Docstoc
					  Group #24
Guercy Metayer
 Louis Chrispin
Jacques House
  Larry Lowe
  Energy Monitoring System
• Measures the power consumption of the house
  or individual appliances
• Detect faulty appliances and where most power
  is being consumed
• Display power in kW/h, the cost in $ and cents
• Send the data to a computer database and
  predict cost of next electric bill.
              Motivation
• Learn how power company measures our
  power consumption for the electric bill
• See how we can help with the energy
  crisis in the residential sector
• We wanted to see if the utility company
  was charging customer correctly
• We all wanted to do a project that has to
  do with power
                The Problem
• No standardized way for consumers to estimate
  electrical energy usage.
• Americans may spend around 4.7 percent of their
  take-home pay on utility bills. Low income residents,
  conversely, will spend an average of 19.5 percent of
  their annual income on utility bills.
• Average household receiving social security or
  family aid spends 19-25% of income on utilities.




                 Source: National Low Income Energy Consortium
Specification & Requirements
• Specs.                         • Req.
  – Measures the power             – Operating Temperature: -5°
    consumption of the house         to 655°C
    or individual appliances       – Accuracy within +5
  – Display power in kW/h, the     – Line voltage = 125 V (rms)
    load, cost, and power          – Class 100 meter with IMAX
  – Send the data to a               = 100 A
    computer database              – Meter constant = 3200
  – Graphical Interface –            imp/kWh
    Windows Compatible             – CT Turns ratio = 300:1
                                   – Meter calibrated at IREF =
                                     10 A
                                   – Power dissipation at Ib =
                                     125 V X 10 A = 1.25 kW
                                   – V1 = 23 mVrms max
                   Block Diagram
                                                                             RMS to DC Converter


   Current Transformers                       OPAMP 741
                                                                                                   Analog to Digital converter




                                                                             Analog Multiplier




                                     Multiplexer 16




                                                                          EEPROM                        Microcontroller
                   Reference Voltage




Potential Transformer

                        Positive Voltage         Positive Voltage
                          Regulator                Regulator




                          Negative Voltage
                             Regulator                 Dual Line Driver
           Topics Covered
•   Overall design layout
•   Microcontroller
•   EEPROM
•   Voltage/Current measurement
•   Communication
•   Display to a Computer
•   Future Work
•   Budgeting and scheduling
    Approaches Considered
• Image Recording            • Panel Connected
  Device (suggested by         Device
  Prof Weeks)                  – Wall mounted box
  – An image recorder            measure power from a
    with sensors to detect       panel
    the six sides of a         – The box sends the
    digital number               data to a remote
  – The image recorder           display
    would in turn transmit     – The box also sends
    the data to a remote         data to PC for monthly
    display                      monitoring
 Energy Measurement Overview
• Show the different types of sensor
  methods there are, and why we choose
  the type of method for this design.
• Describe how the system knows which
  load to pick.
• Looking at the following table, one can see
  the strengths and weakness of the
  different energy measuring technologies
  there are.
Current measurement
 Comparison Table
      Energy Measurement
• Current Measurement
  – Current Transformers (CT)
  – CT placed around each load.
         Current Transformer General
                Specifications
•   Ranges: 0A to 20A
•   Outputs: 0-23mV. Instantaneous
    outputs are voltage only.
•   Core type: Solid core, based on
    dc Hall sensing
•   Voltage Range: 0 to 300 volts
    maximum.
•   Accuracy: ±1.0% for 0-15A, 2.0%
    for 15-20A
•   Working temperature range:
    Typically -20°C - 50°C. Functional
    temp range > –20°C - 70°C
•   Frequency response: DC- 50-
    400 Hz max
•   Mounting: Current transformers
    can be mounted externally via an
    external cable or bracket, fixing
    points provided.
                    Equations
                         • To get the meter error we
                           calculated the measured power
                           versus the calculated power.

                         • Phase error is calculated


                         • The power from the line




                         • The Burden Resistor is
                           calculated
RBurden = Vo / Is
    Multiplexer Applications
• For our project the microprocessor selects
  each CT, one at a time, for measurement.
• The switching is achieved with a solid
  state multiplexer (MUX-16).
• When a particular CT is selected, the
  microprocessor waits ten seconds for the
  circuitry to settle and then takes a reading.
                 Multiplexer
• The MUX-16
  connects a single
  output to one of the
  16 analog inputs
  depending on the
  state of a 4-bit binary
  address.
         Multiplexer Features
• JFET switches rather
  than CMOS.
• Low leakage current.
• Digital inputs compatible
  with CMOS and TTL.
• Temperature ranging
  from -55 to 125 degrees
  C.
• Over-voltage protection
                 Equations
• F = (I0*S0*S1*S2*S3) +
      (I1*S0*S1*S2*S3) +
      (I2*S0*S1*S2*S3) +
      (I3*S0*S1*S2*S3) +…+
      (I16*S0*S1*S2*S3)
Computation and reading the input
 from the Ct and Vt transducer
                 •   A taking the signal from the MUX
                     16
                 •   741 Was used to amplify the
                     signal so that it can used an input
                     for AD536AJD and AD633JN
                 •   The 741 is good at compensated
                     (its frequency response is tailored)
                     to ensure that under most
                     circumstances it won't produce
                     unwanted false oscillations
    Computation and reading the input
     from the Ct and Vt transducer
•   The AD536AJD computes the true
    RMS level of a complex ac input
    signal and gives an equivalent dc
    output level.
•   The AD536AJD will work well
    supply voltage levels from 5 to 36
    volts.
•   The AD536AJD is very efficient in
    converting the rms signal to a dc
    level. There is only a .5% error
    while the conversion is taking
    place.
    Computation and reading the input
     from the Ct and Vt transducer
•   The AD536A is laser trimmed to minimize input and output offset voltage, to
    optimize positive and negative waveform symmetry (dc reversal error), and
    for full-scale accuracy at 7 V rms. As a result in this project, no external
    trims are required to achieve the rated unit accuracy

•   The input and output pins are fully protected. The input circuitry can take
    overload voltages well beyond the supply levels. Loss of supply voltage with
    the input connected to external circuitry does not cause the device to fail.
    The output is short-circuit protected.

•   The actual computation performed by the AD536A follows the equation



•   Looking at the AD536AJD circuit it’s subdivided into four major sections:
    absolute value circuit (active rectifier), squarer/divider, current mirror, and
    buffer amplifier.
Computation and reading the input
 from the Ct and Vt transducer
                              Current Mirror



        Absolute Value;
        Voltage-current
        Converter




                          One-Quadrant Buffer
                          Squarer Divider
Computation and reading the input
 from the Ct and Vt transducer
• The input voltage (VIN), which can be ac or dc,
  is converted to a unipolar current (I1), by the
  active rectifier (A1, A2). I1 drives one input of the
  squarer/divider, which has the transfer function
•                    4I =I^ /I3
                         2



• The current mirror returns a current I3, which
  equals Avg. I4, back to the squarer/divider to
  complete the implicit rms computation.
Computation and reading the input
 from the Ct and Vt transducer
• The current mirror also produces the
  output current, I = 2I . I can be used
                  OUT   4   OUT


  directly or converted to a voltage with R   2


  and buffered by A4 to provide a low
  impedance voltage output
• . The transfer function of the AD536A
  results in the following:
 Computation and reading the input
  from the Ct and Vt transducer
• The AD633 is a complete four-
  quadrant multiplier

• Applications: Multiplication,
  Division, Squaring
  Modulation/Demodulation,
  Phase Detection Voltage
  Controlled
  Amplifiers/Attenuators/Filters

• The AD633 is laser calibrated
  to a guaranteed total accuracy
  of 2% of full scale.
    Computation and reading the input
     from the Ct and Vt transducer
•   -The ADC0831CCN is an analog to
    digital converter. It converts
    continuous signals to discrete digital
    numbers.

•   The ADC0831 series are 8-bit
    successive approximation A/D
    converters with a serial I/O and
    configurable input multiplexers with up
    to 8 channels. The serial I/O is
    configured to comply with the NSC
    MICROWIRE™ serial data exchange
    standard for easy interface to the
    COPS™ family of processors, and can
    interface with standard shift registers
    or µPs.

•   The microprocessor performs an
    analog-to-digital conversion which
    yields a binary number ranging from 0
    to 255.
        MCU Requirement
• Must be easy to use
• Multiple I/O lines
        Microcontrollers

  MCU          Advantages           Disadvantages
             Clock speed: 54 MHz    Chip cost: $18.70
Rabbit3000   Op. Volt.: 1.8-3.6 V   Board cost: $239
             56 I/O pins            No free samples

             Chip cost: $3.81       Clock speed: 16 MHz
ATmega16     Board cost: $79        Op. Volt.: 2.7-5.5 V
             Free samples           Advanced

             Only 33 instructions   Op. Volt.: 2.5-6.25 V
PIC16C56     Clock speed: 20 MHz    One time programmable
             Chip cost: $3.03
                        Chosen MCU
    PIC16C56 features:
•   33 instructions
•   20 MHz speed
•   2.5 to 6.5 operating voltage
•   18 pin chip & 12 I/O lines
•   1 kB ROM, 25 B of RAM
•   8-bit real time clock/counter
    (TMR0) with 8-bit
•   Programmable pre-scaler
•   Power-on Reset (POR)
•   Device Reset Timer (DRT)
•   Watchdog Timer (WDT) with its
    own on-chip
•   RC oscillator for reliable operation
•   Programmable Code Protection
•   Power saving SLEEP mode
Pin Layout
              Programming
• Assembly                  • C Language
  – Advantages                – Advantages
    • Smaller Code Size         • Portability of code
    • Efficient                 • Familiarity Among
  – Disadvantages                 Group
    • Overhead                – Disadvantages
    • Unfamiliarity Among       • Longer code size
      Group                     • Compiler doesn’t catch
                                  all errors
Architecture
              Example Code
Changing the Prescaler:
• CLRWDT                  ;clear watchdog timer
• CLRF TMRO               ;clear prescaler
• MOVLW B'00xx1111'

• OPTION

• CLRWDT                  ;PS<2:0> are 000 or 001

• MOVLW B'00xx1xxx‘       ;setting the prescaler
• OPTION
         Development Board
PICSTART Plus Features:
• Programs PIC
  microcontrollers,
  including program
  memory, configuration
  bits and ID locations
• Works as an application
  on a PC host system
  within the MPLAB
  Integrated Development
  Environment (IDE)
• Communicates with the
  PC via a standard RS-
  232 cable
                            PCB
• PCBExpress.com                   • Ourselves
  – Advantages                       – Advantage
    • Professional                      • Cheaper
  – Disadvantage                        • Fix errors
    • 2 Lots of a 9 in2 board is     – Disadvantage
      $60                               • Raw finish
    • Risky
         Storage: EEPROM
Reason:
• Not enough internal memory on the
  microcontroller.
• It can be erased and it is more durable
  than Flash
         Storage: EEPROM
93LC56 features:
• Sequential read
  function
• 1,000,000 E/W cycles
  ensured
• 256 Bytes
• Data retention: over
  200 years
• Temperature Range:
  -40°C to +85°C
            Power Supply
• Main Power Supply
  Power Requirements
Component       Current (mA)   Voltage (V)   Power(mW)

CT Transducer        0             0                      0
VT Transducer        0             0                      0
MUX16                .2            15                     3
Pic16c56-x           1             3                      3
AMP 741             1.7            15                25.5
AD536AJD            1.2            12                14.4
AD633JN             1.4            15                    21
ADC0831CCN           1             3                      3
93LC56 EEPROM        1             3                      3
7150 RS-232         1.2            7                  8.4
Total               8.7                              81.3
CPU Capture
Capture GUI
      open com port
      while not CRLF
          listen
      //discard first input
      wend

      for i=1 to i=16
      //4 values from microcontroller
         read j,k,l,m
      //index values by channel #
         A[j] = k
         B[j] = l
         C[j] = m
      end-for
      close com port
CPU Display
Display GUI
      //double letter arrays signify past readings
           (BB, AA)
      i=0;while(i<16){
          //subtract past readings
          B[i] = B[i] - BB[i];
          A[i] = A[i] - AA[i];
          F[i] = B[i] + A[i] * 65536;
          // CT = current transformer size
          // LV = line voltage
          // PF = power factor
          // SCAL, SCA2, PRICE

      //Scale to amps
          A[i] = A[i]/SCAL*CT[i]/20;
      //Scale to kw
          K[i] = A[i] *LV[i]*PF[i]/1000;
      //Scale to kwh
          G[i] = (F[i]/SCA2*CT[i]/20*PF[i]*LV[i]/120);
      //Calculate cost
          C[i] = PRICE * G[i] / 100; i++;}
HTML Output
Obstacles
         Hardware Design
• Numerous design changes
• Wasted resources
• Features removed:
  – Wireless CPU serial connection
  – Wireless LCD room modules
    • Temperature sensor
    • Humidity sensor
  – Network connectivity
  – Meter-mounted LCD display
       Presentation Computer
              Display
• UCF computers
  – administrative rights
  – MSCOMM32.OCX error
• Personal laptop
  – Windows Vista (missing MSCOMM32.OCX)
  – USB Ports (serial-to-USB not working)
• Old desktop computer
  –   Windows XP
  –   Serial port
  –   Descent test load
  –   Heavy to carry around
             Model House
• Plastic doll house
  – Cheaper and less initial work
  – Hard to cut/modify plastic
  – It’s a doll house
• Custom wooden house
  – More expensive
  – Easy to modify and wire rooms
  – Looks more professional
                                            Timeline
                       Energy Monitoring
                                                                      Jan 2007          Feb 2007            Mar 2007           Apr 2007
ID                             01/06/2007   04/27/2007   Duration
        Senior Design II                                            7/1 14/1 21/1 28/1 4/2 11/2 18/2 25/2 4/3 11/3 18/3 25/3 1/4 8/4 15/4

1    Research                  1/25/2007    3/8/2007      31d
2    Ordering Parts            1/8/2007     2/1/2007      19d
3    Design Modeling           2/5/2007     3/1/2007      19d
4    Assembly                  2/27/2007    4/9/2007      30d
5    Testing Phase             4/4/2007     4/25/2007     16d

6    Troubleshooting           4/4/2007     4/18/2007     11d

7    Final Report              4/19/2007    4/24/2007      4d

8    Demonstration of Design   4/26/2007    4/26/2007      1d
                                                Budget
                                             Product          Price


Current Transformers(3)                                  $ 81.00
Potential Transformer                                    $ 35.00
AD536AJD: RMS to DC Converter                            Sample
AD633JN: Analog Multiplier                               Sample
16-channel Multiplexer                                   Sample
ADC0831CCN: Analog to Digital Converter                  Sample
93LC56: Serial EEPROM                                    Sample
PIC16C56: Microcontroller                                     $3.05

Development Board                                            $199.1
2N3906: PNP Transistor                                   Sample
LM7805: Positive voltage regulator                       Sample
LM7912: Negative voltage regulator                       Sample
LM7812: Positive voltage regulator                       Sample
SN75150: Dual line driver                                $     2.00
LM741: Operational Amplifier                             Sample
Bread Board                                              $ 15.00
LCD                                                      $ 27.00
Miscellaneous (Resistors, Capacitors, Diodes, etc.)      $ 75.00
                                Work Distribution


Louis                 Jacques              Larry               Guercy

RMS to DC
Converter             Current Transformer Voltage Regulators   MCU


Analog Multiplier     Multiplexer          Dual Line Driver    Programming


Analog to Digital
Converter                                  GUI                 EEPROM

                                                              Computer
Electrical Engineer   Electrical Engineer Electrical Engineer Engineer
Questions?

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:2
posted:1/10/2012
language:
pages:51