home energy management system sponsor: progress energy
Post on 01-Jan-2016
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Dennis Kilgore
Zineb Heater
Ryan Jones
HOME ENERGY MANAGEMENT SYSTEM
SPONSOR: PROGRESS ENERGY
Project Motivation
Power bills only give consumers a look atMonthly power usagePower usage for the entire house
How much power does your home entertainment system use?
What if you could turn your water heater off when you don’t need it?
Standby Power All electronics that are powered by DC power have an AC to DC converter
These converters draw power even when they aren’t in use
Entertainment systems consume power when off, cable box, gaming system, almost every other modern device
Research in leading G8 countries shows that Standby power consumes 8 to 12 percent of a home power bill France – 7% US – 10% Japan – 12%
Goals A system that measures the power
consumption of various household appliances
A system that allows the user to shut the power off any household appliance
A system that monitors the power usage and display it on an LCD screen
A system that can be accessed wirelessly A system that will save more energy than it
uses
Project Overview
Build a circuit to measure both the current and voltage used by an appliance
Build the circuit to control the power on and off an appliance
Write a program to calculate the power and transmit it wirelessly
Display the results on an LCD touch screen
Requirements and Specifications
Measure currents varying from 0 Amps to 15 Amps
Measure voltages up to 120V Control the relay and shut the power off
an appliance Power measured must be within 10%
error
Block Diagram
Hardware
Current Sensing Methods
Current measuring Shunts Current transformers Hall Effect current sensors Magneto resistive Field sensors
Pros and Cons Pros Cons Price
Shunt High Accuracy Heat Dissipation Moderate
Transformer Isolation Large size Moderate
Magnetic High Accuracy Temperature dependency
Moderate
Hall Effect IsolationHigh AccuracyHigh LinearityRepeatable operation
Small Output Voltage
Moderate
Our Decision
AMP25 Hall Effect Linear sensor Linearity 1%, Accuracy +/-2% 25 Amps rating -55ºC to +125ºC Voltage supply Vs 4.5VDC to 10VDC Offset voltage of Vs/2 +/-2% Output voltage proportional to Vs
AMP25
Voltage Sensing Methods
Voltage sensor, expensive, configuration required
Voltage divider, cheap and easy
Power Measurement
What are we calculating: Real Power (P) in Watts or Apparent Power (S) in VA?
P=V*I*cos(θ)
S=V*I
Power measurement Error vs. PF
Power Relay
TRIAC switch, expensive, large Solid state relay switch, small and
reliable
CX240D5 SSR
Ratings of 5A AC or DC control Zero-crossing (resistive loads) or
random-fire (inductive loads) output
SFH620A, Optical Isolator Isolation test voltage, 5300 VRMS High collector emitter voltage Low saturation voltage Fast switching times Temperature stable
SFH620A, Optical Isolator
Schematic Layout
Schematic layout
Schematic Layout
Schematic Layout
Schematic Layout
Schematic Layout
PCB layout
Testing
Testing
Output of Vcc/2 when there is no current Vcc=4.86 V 100W@120V I=P/V=833mA The sensor has an output of 37mV/1A Sensor should have an output of
30.821mV for this load 30.821mV*7 loops = 216mV RMS
Testing
Testing
Testing
Testing
Testing
Testing
Microcontroller
2-3 analog inputsHigh accuracy D/A conversion
2 digital outputs 1 serial i/o
Microcontroller
Arduino Pro Mini
Small Size: .7 x 1.3 inches
Easily Programmable through FTDI
Development Environment
Accuracy
Accuracy is a major concern Any inaccuracy in the measurement
circuit will multiply with microcontroller inaccuracies.
Need to measure and confirm accuracy of the chip.
Voltage vs Integer Calculation
00.
203
0.40
70.
605
0.79
91.
007
1.20
51.
399
1.60
71.
803
2.00
22.
204
2.40
12.
62.
798
2.99
93.
202
0
200
400
600
800
1000
1200
Series1
Measured vs Calculated; Error %
00.
203
0.40
70.
605
0.79
91.
007
1.20
51.
399
1.60
71.
803
2.00
22.
204
2.40
12.
62.
798
2.99
93.
202
0
2
4
6
8
10
12
Series1
Measured vs Calculated; Error %, correction
00.
203
0.40
70.
605
0.79
91.
007
1.20
51.
399
1.60
71.
803
2.00
22.
204
2.40
12.
62.
798
2.99
93.
202
-2
0
2
4
6
8
10
12
Nominal
Addition
Error Correction
00.
203
0.40
70.
605
0.79
91.
007
1.20
51.
399
1.60
71.
803
2.00
22.
204
2.40
12.
62.
798
2.99
93.
202
0
0.5
1
1.5
2
2.5
3
3.5
Series1
Microcontroller Programming Setup
Main Loop
Read Serial Data Function
Print outputs
Setup
Initialize serial communication
Set digital pin 10 to digital output
Set the pin to highTurns on the relay
Main Loop
Take MeasurementsFind high and low of the waveform over 1
sec periodAfter 1 second, print the values to serial
If switch is off, wait to turn back on
Read Serial
Read the incoming serial data and decide what to doIncoming data will be the on/off commandBe able to respond immediately to
commands Microcontroller is always looking for
incoming serial data
Print outputs
Determine the height of the waveformCorrect for innacuracies
○ Hall effect sensor floats at 1.5 mV(integer of 5) when powered
○ Subtract 1 from the voltage measurement
Print the output as comma separated values to the serial comm, to be processed by the screenN#,vol,cur,
Wired Communication
Powerline CommunicationNo range or attenuation issuesRequires Bulkier PartsIncreases size of end unit PCBRequires modifications to home circuitry
depending on the house
Wireless Communication
ZigbeeMesh NetworkingExcellent rangeBetter supports many nodes
Protocol and parts are a mess
Zigbee -> Xbee
Xbee is not ZigbeeXbee is based on the Zigbee stack
It is however a more stable alternative to Zigbee
AT Command Structure The Xbee units use AT commands for
control This allows direct control of the
addressing, and node address discovery Changing the address to a specific node
requires the address to be known
Control Board
Future Designs DK-57VTS-LPC3250
ARM926EJ-S processor 256KB of Internal SRAM 512MB NAND Flash Micro SD (up to 16GB) Ethernet, USB, RS232 Embedded Linux 5V or 3.3V
LCD Touch Screen 5.7” VGA LCD Screen 4 Pin Resistive Touch 1024x768 resolution 18 bit color
User Interface MiniGUI
GNUPlot for graphsMuch of the support is in Japanese
Qt for Embedded LinuxQwt for graphsMore support in English
GUI Mock-Ups
GUI Mock-Ups
GUI Mock-Ups
Software Block Diagram
Integration Receive data from Xbee
Process dataStore dataUpdate graphs
Respond to touchNavigate Menus
Administrative
ResearchParts Acquisition Design Prototype Test0
20
40
60
80
100
120
BudgetItem # Unit Cost ($) Total Cost ($)
Arduino Pro 3 19.00 57.00
Xbee 4 19.00 76.00
PCB 3 20.00 60.00
LCD Screen 1 515.00 515.00
Xbee Adapter 4 11.00 44.00
Hall Effect sensors 4 11.90 47.60
Power Relay 4 13.18 52.72
Resistors, capacitors, etc. 12
Total 863.72
Questions?
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