modular data acquisition system for alternative energy solutions

INDIANA‐PURDUE UNIVSERISTY FORT WAYNE

Modular Data Acquisition System for Alternative Energy

Solutions Senior Design Project

Brian Beer and Leon Tong

11/18/2008

This proposal contains an ideal of how alternative energy sources can be monitored by sensors to achieve maximum productivity and output.

Modular Data Acquisition System for Alternative Energy Solutions

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Table of Contents

Problem Statement________________________________________________________ 2

Market Analsyis___________________________________________________________3

Requirements and Specifications_____________________________________________4‐5

Implementation Methods___________________________________________________6

System Description________________________________________________________7‐10

Sensor Section ______________________________________________________8

Controller Section___________________________________________________ 9

Processor Section____________________________________________________10

Regulatory Standards_______________________________________________________11

Trade‐Off Study___________________________________________________________ 12‐13

Required Resources________________________________________________________14

Project Schedule___________________________________________________________15

Estimated Cost____________________________________________________________16

Return of Investment and Benefits____________________________________________17

Risk Analysis______________________________________________________________18‐19

Risk Identification____________________________________________________18

Failure Mode and Effect Analysis________________________________________18‐19

Teaming Factors___________________________________________________________20


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Problem Statement

The increase in global demand and consumption of energy coupled with an the increase in price for traditional energy resources, such as fossil fuels, has triggered a global awareness and need of renewable and energy efficient technologies. As world markets lean toward “green” energy, the need for efficient and effective means to catalog and acquire data associated with alternative energy solutions has also risen. Current data acquisition solutions are static, non‐ modular, and do not provide the accuracy that is required. A cross platform, accurate and cost‐ effective data acquisition system for renewable energy solutions would provide a means to record, analyze and control power readings from renewable energy solutions. This would aid in increasing the reliability and efficiency in a developing technology.

The purpose of this project is to create a data acquisition system that can accurately and efficiently monitor and record power readings generated by alternative energy solutions. The system would be modular, whereby only small modifications are required to support different types of renewable energy solutions. The system would also be interfaced with current data acquisition software so data obtained from the sensors can be calculated and conveyed to a user‐friendly interface.

The proposed system will acquire the following information:

voltage from an external energy source; current from an external energy source; power factor from an external energy source.

Since the type of signal to be acquired is analog or level signals, an ADC must be used to convert analog electrical signals to a digital value for the computer to interpret. In addition to acquiring data samples, the system will display results on an LCD screen attached to the unit. A non‐volatile storage medium will be used to store acquired data incase of a power outage or failure.


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Market Analysis

Data Acquisition (DAQ) Systems are common in today’s global industries. They are used in a variety of applications from detecting wind speed during air travel to monitoring power ratings from energy sources. The common factor between these products is that they are usually specialized, non‐modular, and in the case for energy power ratings, inaccurate. The proposed system design would allow for, accurate readings, ease of use, and modularity between systems. Table 1 ‐ Product Comparison Table‐ DAQ products in the market today

Product Description Advantages/Disadvantages Price Multimeter Reads current and Voltage Not very accurate, specifically for

troubleshooting purposes, not for online measurements

Inexpensive

National Instruments DAQ module

Reads current and voltage and provides connection to a PC

Accurate, but does not provide a user interface. Connections must be done manually

Inexpensive

IOTech Mix‐Signal Measurement instrument

Reads current and voltage and provides connection to a PC

Accurate and modular, but does not provide a user interface. Mostly for engineers

Expensive

Modular Sensor DAQ System (this project)

Reads current, voltage, logs data, makes calculations, and displays final data on user‐friendly application.

Very accurate. Can be used for different applications. Sensors are modular.

Moderate

Accuracy, flexibility, usability, and price are the major criteria for determining an effective DAQ system. Unfortunately, current products in the market today do not provide for all three, there must be trade‐offs. For instance, although IOTech’s Mix Signal Measurement Instrument is accurate and modular, but it is expensive and does not provide a user interface. Refer to Table 1. The goal of this project is to develop an accurate and modular data acquisition system to monitor and display power ratings from alternative energy solutions, at a lower cost than current systems. Accuracy will determined by quantization error, non‐linearity of an ADC, aperture error of the ADC, signal conditioning and other constraints of data acquisition. The proposed system should be able to obtain data with an accuracy precision of thousandths of a volt or 99.6% (determined by the accuracy of a 10‐bit ADC).


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Requirements and Specifications

This section will detail the physical pieces that the system will be composed of, as well as specifications, and requirements. • Sensors that can operate with 130V supply; • PC for user interface and configuration; • EEPROM for non‐volatile data storage; • LCD to display data and graphs; • C Language for programming; and • Push‐pad for user input and configuration Voltage and current range and percent accuracy is driven by the operating range of the ADC and microcontroller that will be used. Table 2 shows a range and precision matrix that is based on the C8051F320 microcontroller. Table 2 – Voltage and Current input/output range and precision

Voltage Current Range Operating Range Data Precision Operating Range Data Precision Input 110‐130V ±5% from 120V 5A TDB Output 4.75‐5.25V ±5% from 5V 30mA‐50mA TDB

Physical Components The system will be divided into three main sections, each of which will have certain subcomponents necessary for operation. The “sensor” of the device will be composed of a transformer/transducer system that will bring down dangerously high voltage levels to levels that are usable by a Microcontroller. This section will be used as the “sensor” mechanism to obtain power readings from an external power source. Specifications on which components to use were driven by the operating ranges of the microcontroller and heat and resistor requirements for current. Refer to Table 2. Table 2 ‐ Sensor Section Components – Description and Specification of system sensors

Component Description Specification 546‐166RS. Potential Transformer to drop 120V to 5V Must be able to drop 120V to at least 5V

TBD Current Transducer to regulate 5A to 30mA Tolerance of >5A and must meet resistor and heat requirements.

*TBD – To Be Determined at a later time. The second portion or the “controller” will be composed of a microcontroller with a built in analog‐to‐digital converter. This section is used to convert analog signal inputs from the sensors to digital signals that can be processed by the “controller” and other parts of the system. The controller must be able to communicate with the “sensors” section and the third section. The


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specification for this section was driven by the need for a quick, accurate, and scalable system. So, the controller should be able to interface with an LCD display, a maximum of 10bit ADC (any larger could cause delay in processing), also at least 8kB of flash memory to store data. Refer to Table 3.


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Table 3 ‐ Controller Section Components – Microcontroller with a built in ADC and flash memory Component Description Specification SiLabs C8051F320

16 bit microcontroller with a built in 10 bit ADC Must have USB interface, <10bit ADC for speed. >8kB Flash Memory

The third section will be the “Interface” of the system. It will be composed of a LCD screen and push button. The push button will be used as an input medium for users to toggle or navigate through various screens. DAQ software this will be used. Refer to Table 4. Table 4 ‐ Interface Section Components – Display and user interface components

Component Description Specification

HD44780 LCD

20x4 HD44780 Blue STN LCD with White Text and LED Backlight.

Must include backlight and at least 4 rows.

Push Buttons TBD Must have at least 3 buttons.


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Implementation Methods

The procedure for implementing this design involves several steps. The first step involves defining the scope and goals of the project. The ultimate goal is to design a modular data acquisition that can produce accurate data that can be stored and used as a monitor/control mechanism. Once the components have been chosen (see Trade‐Off Study), prototype boards will need to be developed. The prototype boards allow experimentation with features of the hardware. This stage is crucial in the success of the project. The stage should allow for a good assessment on the operating limits of the system. There is a blend of hardware design as well as software development. Prototyping is the first step in building the system. Schematic capture software is used to design the electrical circuit for the Sensor and control units. Once the circuit has been drawn, it will be transferred to another software application to physically create the layout of the circuit board. Rapid prototyping machines are available for students in campus labs. There are also companies that provide circuit board cutting services at a very low cost. The circuit board produced has several components, including a microcontroller with a built in ADC, USB connectors, and various other passive components. The board will have to interface to a current transformer and potential transformer at the input site and LCD at the output side.


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System Description

The proposed project idea is a modular data acquisition system that is composed of sensor and processing components to read, calculate, and display power ratings. The system is divided into three primary functional sections: sensors, controllers, and processor. The first section or “sensors” section will be composed of a transformer/transducer system that will bring down dangerously high voltage levels to levels that are usable by a Microcontroller. This section will be used as the sensor mechanism to obtain power readings from an external power source. The section or “controller” section will be composed of an analog‐to‐digital converter and microcontroller. The third section or “interface” will be composed of an LCD and push button. The LCD and push button must interface with the “controller” section and display the desired data. Refer to Figure 1 for more details. Figure 1 ‐ System Block Diagram – Overall system structure


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Sensor Section

This section provides input for the system. There are two main components in this section: a potential transformer unit and a current transformer unit. The potential transformer will be used to drop down the supply voltage from an estimated industrial standard of 130V rms to 3V. The 3V will be fed into an Analog‐to‐digital converter located on the microcontroller. (Since 130V to 3V potential transformer is difficult to obtain, additional circuitry maybe required to drop down the voltage to 3V.) Refer to Figure 3 for more details. Figure 3 ‐ Sensor Block Diagram – sensor section functional block diagram

PT

CTCurrent to Voltage

Converter

Sensor


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Controller Section

This section allows for the conversion of analog data to digital data. It controls inputs and outputs for the DAQ system. First analog data is converted to digital data via the analog‐to‐digital converter. The data is controlled by the CPU of the microcontroller which creates an output that is usable by data acquisition software. The sample rate is still to be determined, so having 16kB flash memory to use would allow for additional scalability to the system. Refer to Figure 4 for more details.

Figure 4 ‐ Controller Block Diagram – basic functional diagram of controller showing voltage inputs and an output


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Processor Section

This section provides for calculation of data and a user interface. The data acquisition software is used to interface with the controller to obtain data readings. Once data is processed with the software, it is stored to a database and the real time results will be displayed to the user through the LCD. The database and LCD will communicate with one another to display and store the most up‐to‐date readings. Refer to Figure 5 for more details.

Figure 5 ‐ Processor Block Diagram – basic functional diagram of processor section

Interface

LCD EEPROM

Push Button


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Regulatory Standards

United States power regulations and standards must be taken into account. According to ANSI and the United States Department of Commerce, United States power standards are Voltage: 120V; Frequency: 60Hz. Configuration of hardware and software must coincide with government power standards and regulations.

LabView licensing agreements must also be examined. Although this project is intended for educational use, it could be marketed as a proprietary product. National Instruments licensing agreements prohibit the distribution of software written in LabView without prior consent. That is why we will only be using LabView for testing purposes and will be generating our code in assembly and C language.


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Trade‐Off Study

Many different solutions exist for accomplishing the requirements and goals of this project. From the list of software and hardware methods, there are only a few that will be optimal for this project. The Assembly language gives the programmer the most flexibility with the target system but the code is practically not portable to any other platform. This is a problem because this ties the system design to one specific piece of hardware. The C programming language is standard for PC, so can be used to integrate into other types of systems with very little modifications. The use of a microcontroller (MCU) is almost inevitable when dealing with mix signal processing. Making a choice for the appropriate chip is a tradeoff between the different criteria for the considered system component. An analysis is to be performed which will rank each of these criteria. The trade‐off study in Table 5 shows a variety of microcontrollers ranging from 16 bit to 64bits. Large supply voltage range, ~16kB flash memory, small data converter, and a built in USB are the main criteria for selecting a microcontroller. The C8051F320 will be used, since it fulfills the necessary requirements and has a dedicated USB port.

Table 5 ‐ Microcontroller Trade‐Off Analysis – analysis on different types of microcontrollers that could be used for this project

Make Model CPU Flash Memory

Chann. Data Converter

Vref Supply Voltage

Dedicated USB?

TI MSP430F1232IDW 16 Bit 8 kB 12 10 Bit ADC 2.5 V 1.8‐3.6V No

TI TMS320F2811 32 Bit 256 kB 16 16 Bit ADC 2.1 V 3.14 ‐ 3.47 V No

SiLabs C8051F02x 32 Bit 64 kB 5 12 Bit ADC 1.2 V 2.7 ‐ 3.6 V No

SiLabs C8051F350 64 Bit 8 kB 4 24 Bit ADC 2.5 V 2.7 ‐ 3.6 V No

TI TMS320LF2403A 16 Bit 32 kB 8 10 Bit ADC 3.3 V 3.3 V No

SiLabs C8051F320 16 Bit 16 kB 17 10 Bit ADC 2.4 V 4.0‐5.25V Yes

Both voltage and current transducers will also be required to fulfill the requirements of the project. The trade‐off study shows several methods of measuring voltage levels. The Potential Transformer will be used to obtain voltage readings since it will be inexpensive, accurate, and reliable. In addition to the Potential transformer, an additional voltage divider circuit may be needed to bring voltage down to the required rating. Refer to Table 6 for more details.

A current transducer will be used to obtain current readings since it will provide for a high level of accuracy, allow for data storage, and relatively inexpensive to acquire.


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Table 6 ‐ Voltage Transducer Trade‐Off Analysis

Table 7 ‐ Current Transducer Trade‐Off Analysis

Solution Description Disadvantage Advantage

Current Transducer Regulate 5A to 30mA Does not meet heat requirement

Inexpensive and accurate

Current Transducer Regulate 5A to 30mA Needs extra components to measure

Inexpensive, accurate, and reliable

Multimeter External device Inaccurate and cannot be stored Inexpensive, easy to acquire and implement

Table 8 ‐ Programming Language Trade‐Off Analysis – Analysis on different types of programming languages that could be used

Language Portable Difficulty Libraries C Yes Moderate Yes Assembly No Hard None

Table 9 ‐ Data Acquisition Trade‐Off Analysis – Analysis on different types of DAQ software that could be used

Software Portable Difficulty Learning Curve Built in functions LabVIEW Yes Moderate Moderate Yes Diadem Yes Hard High Somewhat

Solution Description Disadvantage Advantage

VDR Circuit Voltage Divider Circuit to bring down ~120V to 3V

High voltage can overload circuit Inexpensive and easy to construct

Potential Transformer

120 down to 5V Needs another component to drop 5V to 3V

Inexpensive, accurate, and reliable

Step‐down Transformer

45:1 step down ratio transfomer Inaccurate, power factor would be skewed

Inexpensive and easy to acquire


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Required Resources

There are a number of resources required to complete this project. These resources range from physical devices to knowledgeable individuals. This section will outline the resources that have been used and others that will be required. People The knowledgeable professors at Indiana University Purdue University Fort Wayne have been a great help so far in giving suggestions and advice related to this project. So far advice has been received from the following professors: Professor Paul Lin, Professor Gary Steffen, Professor Peter Goodman, Professor Iskander Hack, Professor Ed DeWitt and Dr. Suzanne Rumsey. Hardware

• Current Transformer • Potential Transformer • Analog‐to‐Digital Converter • Microcontroller‐ SiLabs 8051 • Flash programmer, PCB Prototyping tools, 8051 Development kit

Software

• C Language and Integrated Development Environment • National Instruments ‐ LabView • Arcamedies compiler

Facilities

• The IPFW campus computer labs have been used for research and the available test equipment may need to be used for future testing.

• Orion Wind power plant ‐Fowler, Indiana.


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Project Schedule

This Gantt chart outlines the schedule for task completion for Phase I and estimated schedule of task for Phase II. The chart is based on milestones and basic gate reviews whereby each task will generally finish will trigger a task start. We anticipate changes to the deadlines will be needed as more information about the project is obtained.


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Estimated Cost

The development of this project will not require a large investment. The cost for most of the electrical components that will be used typically range from several pennies to a few dollars. But, most of the companies that produce these products are willing to give out free samples in large enough quantities to build a fully working prototype. Although the LabView software is provided by the department, licensing costs for distribution of proprietary software must be examined. Table – Estimated cost for each component

Component Cost

Microcontrollers Provided by SiLabs as free samples

Current Transformer ~$35.00 USD

Potential Transformer $34.42 USD

Development Tools – Silicon Labs 8051 development board Free from Professor Goodman

Samba Server Free Software

mySQL Database Free Software **Note that labor hours and costs will not be included in this cost analysis.


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Return of Investment and Benefits

Since there are no stakeholders involved such as companies or clients, there are no direct monetary benefits to the completion of this system. Nonetheless, the system design does have its own benefits. The data acquisition unit and software is excellent for modular implementation on different types of energy power platforms. Although this particular design is geared towards a Wind Power system, potential clients can easily deploy the system in almost any environment and tailor the system to suit their needs. The software will be written using the Agile Programming convention, so additional data and graphs can be implemented with very little effort.


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Risk Analysis

This section deals with identifying the risks associated with the project design and development process, ranking the risks according to severity and probability, and how to go about minimizing those risks. The first step in risk analysis is to identify the appropriate risks, and the next step involves analyzing those risks. Risk Identification Performance Risk

• System will suffer interference • Insufficient range • System Inflexibility

Management • Wrong components ordered • Goals aren’t reachable • Requirements aren’t reachable

Schedule • Parts arrive late • Objectives not met by deadline

Risk Analysis Table One of the major potential risks associated with this project is the compatibility between the C8051F320 Microcontroller, the LCD, and the eeprom. Getting these three components to communicate with each other is key to the success of this project. Other risks are displayed on the Risk Assessment Matrix below. Refer to Table 10.


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Table 10 – Risk Assessment Matrix Severity of

Consequences F

Impossible E

Improbable D Remote C

Occasional B

Probable A

Frequent I

Catastrophic 4,5 3 7 II

Critical 6 1 III

Marginal 2 IV

Negligible 1. Networking problem with LabView for testing 2. Database Server problems 3. Web Server problems 4. Transducers inability to detect voltage/current 5. Microcontroller and LabView communication for testing 6. Resistor circuit failure 7. No communication between sections

Teaming Factors

This project is a team effort between Leon Tong and Brian Beer. All research and project planning are to be worked on together. The two main segments of the project development are hardware and software. Leon will specialize in the software engineering aspect whereas Brian will specialize in the hardware/circuit design. But, both members of the team will provide input and assistance to both aspects of the project.


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References

Ed DeWitt (private communication), 2008. Paul Lin, P.E. (private communication), 2008. Pete Goodman (private communication), 2008. Electricity Forum, Potential Transformer Explained, 2008,

<http://www.electricityforum.com/products/potential‐transformer.htm> (accessed November 20, 2008).

Equitech, World Power Standards, 2008, <http://www.equitech.com/support/worldpwr.html>

(accessed December 10, 2008). G. Pottie and W. Kaiser, Principles of Embedded Networked Systems Design, Cambridge:

Cambridge University Press, 2005. IOTech, Signal Conditioning & PC‐Based Data Acquisition Handbook, 3rd Edition. 2008. J. Travid and J. Kring, LabView for Everyone 3rd Edition, New Jersey: Prentice Hall, 2007 National Instruments, Data Acquisition, 2008, <http://www.ni.com/dataacquisition/> (accessed November 20, 2008).

modular data acquisition system for alternative energy solutions

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