lafayette photovolt aic research and development system 2010

Photovoltaic Research and Development System 2010

Lafayette Photovoltaic Research and Development System 2010

Dan

1

Presentation Outline

System Introduction

Project Team

System Block Diagram

2009 vs. 2010 Comparison

2010 System Focus

Switch Controller (SC)

Filter Inverter Box (FIB)

Supervisory Control and Data Acquisition (SCADA)

Demo App and Tower Design

Safety Loop and Hardware

Project Status

What is the Lafayette Photovoltaic Research and Development System?

PV Array

Subject to a Statement of

Work

Commercial Grid Tie Inverter

Requirements based team

oriented capstone project

2kW solar energy system that converts high voltage DC to 120V AC RMS signal of 60Hz

A test space for students to learn about energy issues and power engineering.

Dan

The Lafayette Photovoltaic Research and Development System is a multi-year, multi-team, Senior Electrical and Computer Engineering capstone project that consists of the designing, implementing, and testing of a 2kW solar energy system. The main requirement of the system is to convert high voltage DC from the photovoltaic array to a 120V RMS AC signal of 60Hz.

The project began in 2009, when students started designing a system that would use the energy acquired from the solar panel array mounted on the roof of Acopian to power an AC load.

Any excess energy not being used to power the load is stored within the system in the battery bank so that when the PV arrays are not producing enough energy to power the load, the difference is drawn from the energy stored in the battery bank.

The systems main elements consist of a solar panel array, an Energy Storage System containing batteries, a Filter-Inverter Box containing an AC conversion system, A Raw Power Interface that connects the solar panels to the rest of the system, and a Switch Controller that regulates the high voltage path between the PV, the batteries, and filter/inverter.

The system also includes a commercial grid-tie inverter converts the DC to AC so the photovoltaic power can be used by the College when the system is not being used for student project work

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Main Requirements

Automatic charge and discharge the LiFePO4 batteries

Delivery of 120V RMS, 60Hz 0.05% AC

Monitor, store and display real time temperature, voltage, and current data from all subsystems

Safety precautions to safely shut down the system if a fault is detected

Dan

LPRDS is a requirements driven, team based, design project that is subject to a 30 page Statement of Work that includes 256 requirements. This document makes sure students meet various project requirements such as management requirements, deliverables, technical requirements, and electrical and hazmat standards.

There are dozens of project requirements for each component of the system with an emphasis on system integration.

Listed are the main technical requirements of the system. They include the charging and discharging of the batteries, the delivery of AC electricity, the monitoring, storing, and displaying of real time temperature, voltage and current data from all subsystems, and the implementation of safety precautions to safely shut down the system if a fault is detected.

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System Introduction

Project Team



2010 System Focus






Project Status

Project Team

Began in 2009 with a 22 student and 2 professor team

2010 team consists of 14 students along with the 2 original professors.

Over 40 people have contributed to this project

Dan

The Lafayette Photovoltaic Research and Development System is a multi-year senior Electrical and Computer Engineering capstone project that began in 2009 with a team of 22 students and 2 professors. The same 2 professors along with the current fourteen Electrical and Computer Engineering seniors make up the current 2010 design team.

The current team has organized itself into smaller teams, typically of four or fewer people, to focus on the technical design of each subsystem. At the same time, the team members also fill management and systems engineering roles.

6

Systems Engineering Exposure

Much of todays engineering is system engineering

System architecture issues

Interface design and documentation

Configuration management

Scheduling

Opportunity to manage complexity

Dan

This project has required constant effort from management and systems engineers to maintain communication between subsystem teams and make system level decisions, all while maintaining focus on the main project goals.

Much of todays engineering is system engineering. This design team has been given an unique opportunity that not many undergraduates get a chance to do. This project has provided many members of the team with leadership opportunities as well as exposure to a design team environment that smaller projects cannot replicate.

At the beginning of the semester, the team was not always organized and on track to complete the project. However, the team has developed a clear project schedule, strict budget, distinct goals, and a better idea of how to work efficiently individually and as a whole which enabled us to make as much progress on the project as we did.

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Other Engineering Exposure

Exposure to mechanical issues

Most ECEs have little exposure to mechanical issues

Board layout

Subsystem Box layout

Assembly drawings

Exposure to safety issues

Safety lecture

Safety plan

Students limited to 30V

Lock out tag out

Must design with safety in mind!

High voltage isolation

HV/LV separation

Dan

Not only are members of the design team being exposed to a larger design team dynamic and leadership roles, but they are also being exposed to both mechanical and safety issues.

Most Electrical engineers have little exposure to mechanical issues such as board layout, subsystem box layout and assembly drawings. This project exposes the design team to many these issues.

We have also been exposed to safety issues. Students are limited to only 30V and the lock out tag out system has been adopted. Each subsystem includes high voltage isolation and includes a protective shield over the high voltage sections in each subsystem box to ensure safety.

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System Introduction

Project Team



2010 System Focus






Project Status

Nick

9


Nick

10

System Block Diagram - PV

PV Array converts solar energy to electrical energy

Nick

There are 10 solar panels connected in series on top of the Acopian Roof. The main function of these panels is to convert the solar energy into electrical energy,

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System Block Diagram - RPI

The RPI Accepts high voltage DC from the PV array and delivers it to the rest of the system

Main safety hub

Nick

The main purpose of the Raw Power Interface is to accept high voltage DC from the roof-mounted PV array and deliver it to the rest of the system.

The RPI also is the safety hub of the system; it monitors current on high voltage lines and sets off a safety alarm if it detects a ground fault. All the subsystems are connected to a safety interface, and when a safety fault is detected anywhere in the system, the subsystems disconnect from high voltage and enter a fault state.

Safety faults include a ground fault interruption, overheating in any subsystem, or the failure of any subsystem. The safety interface also includes high voltage isolation relays to prevent the conduction of high voltage.

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System Block Diagram - ESS

Battery Bank consisting of 64 3.2V Lithium Iron Phosphate Batteries

Creates 12V for other systems

Nick

Within the ESS is a battery bank containing sixty-four 3.2V Lithium Iron Phosphate Batteries organized in sixteen packs of four. These batteries are connected in series to produce a nominal voltage of 205V and are used to store the excess energy from the PV array that is not delivered to the load.

The ESS also creates 12V and 5V from the batteries and provides these voltages to the other subsystems, where they are used to power chips and other circuitry.

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System Block Diagram - FIB

Receives high voltage DC and converts it into a 120V RMS sinusoidal AC signal of 60 Hz

Nick

The main purpose of the Filter Inverter Box is to receive the high voltage DC and convert it into a 120V RMS signal of 60Hz.

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System Block Diagram - SC

Regulates the high voltage path between the PV, batteries (ESS), and the filter/inverter (FIB)

Nick

The main purpose of the Switch Controller is to regulate the high voltage path between the PV array, the ESS, and the FIB.

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System Block Diagram - SCADA

Higher-level operation

Data collection of the other subsystems.

Nick

The Supervisory Control and Data Acquisition subsystem controls the higher-level operation and data collection of the other subsystems.

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System Introduction

Project Team



2010 System Focus






Project Status

Jeff

17

2009 vs. 2010 Subsystem Comparison
Subsystem2009 Status2010 StatusRPIMade complete subsystemReused 2009 subsystem with minor reworkESSMade complete subsystemReused 2009 subsystem with minor reworkFIBPrototype made but explosion occurred and also did not meet frequency or THD specificationsUsing the same topology; made a new filter and inverter that meets specificationsSCNot madeCreated a new subsystem to better enable battery and energy managementSCADANot Integrated with rest of system, but made Data Acquisition boardsUsed 2009 Data Acquisition Boards with minor rework and used ~100 lines of last years code.Added ~5000 lines of code and working website monitoring and displaying both LPRDS and the Sunny Boy

Jeff

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2009 vs. 2010 Miscellaneous Comparison
2009 Status2010 StatusPCB Boards DesignedDesigned 7 (1 redesigned twice) Reused 1, redesigned 1, and designed 1 from scratchDemo App and Tower AestheticsHad a poster with LEDs that was displayed on the tower; PicoLCDCommercially bought lettering; PicoLCD; bright LEDs; Demo App using LCD display monitorCables kits1422Subsystems4Reused 2, redesigned 1, designed 2Subsystem Connectors2740

Jeff

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2009 to 2010 Major Changes

Power management algorithm (SC)

Working inverter/filter

Integrated SCADA

Demonstration application

2009 Top Level Diagram Comparison

2010 Top Level System Diagram


System Introduction

Project Team



2010 System Focus






Project Status

System Testing

Subsystem QA

Low Voltage Testing

Basic System Functionality

Battery Management

High Voltage Testing

Reliability and Maintainability

Laura

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Regulates the high voltage path between the PV, batteries (ESS), and the filter/inverter (FIB)

Student Designed

Data Acquisition PCB Board

Student Designed Box Layout and Wiring Scheme

James

The Switch Controller directs power between the RPI, the ESS, and the FIB via two high voltage switches.

One switch disconnects the RPI and powers the load directly from the batteries, and the other disconnects the FIB in order to recharge the batteries.

The Switch Controller switches are operated based on an algorithm. This algorithm is executed by the Supervisory Control and Data Acquisition subsystem.

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SC ALGORITHM

James

The Switch Controller algorithm is based on the voltage measured across the battery pack.

Switch A will remain closed until the batteries are charged up to 100%, where Switch A opens to prevent the overcharging of the batteries. Also as long as the battery charge is above 55%, Switch B will be closed to conduct power to the FIB, which means there will be enough power present to run the FIB.

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SC ALGORITHM

James

If the batteries are fully charged at 100% of their capacity, Switch A between the RPI and ESS will be opened in order not to overcharge the batteries. Switch A will remain open until the batteries are discharged to 65%, when it will close to recharge the batteries before over-discharging occurs.

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SC ALGORITHM

James

If the battery pack discharges below 20%, Switch B will be opened in order not to over-discharge the batteries, directing all incoming power to the battery stack.

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SC ALGORITHM

James

If the system goes into a fault state both switches will remain open until the fault is cleared. Once the fault is cleared, the system will continue operating based on the state of the system before the fault.

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BATT MGMT APP STATE TRANSITION DIAGRAM

SoC Thresholds:

100% = 235V

65% = 205V

55% = 195V

20% = 165V

James

31

State of Charge

Low Voltage Testing

Connect the system for DC Load Integration

PV DC Source

Disconnect FIB

DC Load

Laura

33

Force LPRDSthrough all possiblestate transitions

Attempt illegal statetransitions

Low Voltage Testing-Basic Functionality

Laura

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Force the SCthrough allpossible statetransitions

Two transitionsshould notoccur

Low Voltage Testing-Battery Management

Laura

35

Reliability and Maintainability Test

Run the DC Load Integrated system for 24 hours

No unexpected faults or failures occur

No components overheat

Laura

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System Introduction

Project Team



2010 System Focus






Project Status


Consists of:

H-Bridge

Low Pass Filter

Microcontroller

FIB PICTURE

Receives high voltage DC and converts it into a 120V RMS AC signal of 60 Hz

Student Designed

Low Pass Filter

Student Designed

H Bridge PCB Board

Student Programmed Microcontroller

Student Designed Box Layout and Wiring Scheme

Berto

38

AC Inverter

Microcontroller controls IGBT inputs by Pulse Width Modulation

4 high power insulated

gate bipolar transistors

(IGBTs) in H-bridge

Allows voltage to be alternated in opposite directions to create sine wave

Berto

39

Filter/Transformer

Filter

Removes switching frequency

THD of less than 3% required

Transformer

Reference output of FIB to building ground

Isolates the connection to the load

Humberto

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FIB Testing Requirements

Frequency = 60Hz .05%

Amplitude = 120Vrms 5%

Total Harmonic Distortion (THD) < 3%

Conducted emissions requirement of average Amplitude at 150KHz < -54dB and peak at 150KHz of < -41dB

Bill

41

Frequency Testing

Test setup

Oscilloscope with inputs from:

Signal generator

Differential output of filter

Hold one waveform on scope and time a full cycle of the other waveform across the first waveform

The inverse of this time is the frequency difference

Bill

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Frequency Results

Time

204s

Frequency difference

1/204s

.0049Hz

Spec: 60Hz.05%

Measured: +0.008%

Result..PASS

Bill

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Amplitude Testing

Set power supply to nominal battery voltage (205Vdc)

Plug in wall transformer to output of system

Measure the RMS voltage on oscilloscope

Scale by factor of transformer

Specification: 120VACrms 5%

Result: 119VAC ... PASS

Bill

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Capture waveform on digital oscilloscope

Import data into MATLAB

Write program to calculate THD

Run program

Specification: 3% THD

THD Testing

Steve

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THD Results

THD calculated to be .157%.......................................................................PASS

Steve

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Conducted Emissions Testing

Capture data on a digital oscilloscope

Import data into MATLAB

Calculate the FFT from the output waveform

Examine results above 150KHz

Steve

47

Conducted Emissions Results

Peak at -16.93dBInconclusive

Steve

48


System Introduction

Project Team



2010 System Focus






Project Status


Controls higher level operation and collects data from each subsystem

State Manager App

Battery Management App

Maintenance App

Demo App

Chris

The Supervisory Control and Data Acquisition subsystem controls the higher-level operation and data collection of the other subsystems.

The control of system functions is handled in three applications, which are circled in the bottom picture.

The Battery Management App runs the SC algorithm, the Maintenance App provides a control interface to system functions, and the Demo App provides a real time demonstration and explanation of the system on a large LCD display.

Each subsystem contains a Data Acquisition Board that measures the relevant current, voltage, and temperature within the subsystem. Using a FitPC, SCADA polls each subsystems Data Acquisition Board for data and stores it in a database.

Graphs and analyses are then generated to view and evaluate system operation and performance over time. SCADA also runs a website that provides a description of the system and displays the current system status.

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Software Top Level Diagram

Data Acquisition Boards

Reused from last year with a few minor changes.

4 boards total: RPI DAQ, ESS DAQ, SC DAQ, and FIB PCB.

Serve as a hardware interface to sensors and switches.

Chris

52

Sunny Boy Communication

Communication established with the Sunny Boy inverter using RS-485.

Did not have to buy the Sunny Beam, saving $280

Available Sunny Boy Data:

Total energy saved

Voltage and current being delivered to the grid

voltage and current drawn from the PV array

AC output frequency

Aaron

53

MySQL Database

Stores system information

Sensor Readings

Fault and Event Logs

System State

Allows for long term data analysis

Solar panel performance by month or season

energy generated per year

Space to store over 5 years of data

Provides the website with data

Kots

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Website

Directly interacts with the database using PHP.

View data from any sensor over a specified date range.

View logs stored in the database over a specified date range.

lprds.aec.lafayette.edu

Brad

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System Introduction

Project Team



2010 System Focus






Project Status

Tower Display

LED indicator lights

Demo App on LCD display

Pico LCD indicating system state

FIB & SC- digital meters for voltage, current, and temperature

System output- Analog gauges showing voltage and frequency

Kots

57

Demo App

Goal: educate passersby about LPRDS and demonstrate system capabilities

Simple descriptions, diagrams and live data

Simple user interface

Coded in C++ using QT and the LPRDS API

Upcoming Hardware Expansions

Touch sensor navigation

Demo outlet control

Demo App Screenshots


System Introduction

Project Team



2010 System Focus






Project Status

Safety Loop

Safety is an integral part of our system

Each subsystem contains part of the safety loop

Safety loop must be closed in order enter and stay in the operational state

Safety loop consists of 4 wires

Two for the loop itself

Safety 12 which signals if the safety loop is closed

Safety 12 ground

Andy

61

Safety Loop Diagram

Andy

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Safety Loop Hardware

SCADA Interface Box (SIB)

Purchased for USB controlled relay& digital input ports

Added feature of two RS485 ports

Safety to Software Interface Board

Designed to control the alarm

Ends the safety loop with thebig red emergency button

ALARM

Andy

63


System Introduction

Project Team



2010 System Focus






Project Status

Budget Current Spending
Section BreakdownSCADA$ 229.45 Conn. & Cables$ 133.99 FIB$ 935.51 ESS$ 58.93 SC$ 103.79 DAQs$ 417.65 Snubbers$ 82.61 Andy Misc.$ 174.66 AC Load$ 612.79 TOTAL SPENT: $ 2,749.38 Remaining: $ 250.62

Aaron

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Power Budget

RPI: 3.89W

ESS: 1.42W

SC: .9W

FIB: 6.03W

SCADA: 7W

Safety & Display: 1.29W

DAQ Boards: 3.99W

Total: 25W

Amount Allowed: 37.5W

Nick

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RPIDAQESSSCFIBSCADASafety and Dislpay3.88919999999999983.99337499999999951.41819999999999810.96.20500000000000171.5886999999999998

Major Requirements Achieved

Raw Power Interface

Contains main logic for safety

Energy Storage System

ESS provides LVDC power for all subsystems

Filter-Inverter Box

Provide 120V RMS, 60Hz AC power

Supervisory Control And Data Acquisition

Perform supervisory functions on all subsystems

Log system data (sensors, states) into the database, retrievable on the website

Safety

All subsystems must be connected to the safety interface

Demo and Display

Mark

67

Major Requirements to be Achieved

Switch Controller

Switching algorithm


Operational States

Power Independence

FIT PC, display monitor

Documentation

Must be complete and correct

Major Requirements Not Achieved

Energy Storage System

Per-cell management

Standalone operation

Internally protected from excessive charge/discharge

Filter-Inverter Box

Measure phase angle between voltage and current, and power factor


Monitor voltage, current, and temperature in all subsystems

HV PV Integration

Future Improvements

Meet the requirements we are not meeting

Snubbers for when incorporating PV Array

Single Cell Battery Management

Power independence

System Control via website

Maximum Power Point Tracking

Demo Touch Sensors

Mark

70

Special Thanks To:

Dr. Jemison

Professor Nadovich

Andy Langoussis

Nicolette Stavrovsky

Mark

71

Questions?

Mark

72

S3

A = CLOSED

B = CLOSED

PWM = ON

S4

A = OPEN

B = CLOSED

PWM = ON

S2

A = CLOSED

B = OPEN

PWM = OFF

S1

A = OPEN

B = OPEN

PWM = OFF

Charge @ 8A to 3.65V (100%), Discharge @ 5A to 2.57V (20%)3.65V (100%)2.57V (20%)2.94V (47%)3.20V (65%)3.65V (100%)2.57V (20%)3.33V (76%)BATTERY: S-693.04V (55%)

Charge @ 8A to 3.65V (100%), Discharge @ 5A to 2.57V (20%)

3.65V (100%)

2.57V (20%)

2.94V (47%)

3.20V (65%)

3.65V (100%)

2.57V (20%)

3.33V (76%)

BATTERY: S-69

3.04V (55%)

SC

RPI

ESS

SCADA/SIB

FIB

HV

from PV

+

-

Ground

Fault

Monitor

Safety Reset

Button (Green)

Manual Trip

(red)

Temperature-

Controlled

Switch

HV

Isolation

Relay

System 12V

from ESS

Safety

Relay

HV

Isolation

Relay

Switches

HV

Isolation

Relay

Safety Loop

HV

to

Output

Safety 12"

Safety Loop

Safety Loop Return

Safety Loop

Safety 12"

Safety 12"

DC

RPI

System12V DC

Safety 12V Loop

Temp Sensor

ControllableRelay

Temp Sensor

Controllable Relay

Temp Sensor

SC

HV Relay

SC

Safety Loop

ESS

RPISafety Relay

RPI

ESS

HV Relay

FIB

SIB

ControllableRelay

Temp Sensor

ControllableRelay

Temp Sensor

FIB

HV Relay

SIB

12VDetection

SIB

ControllableRelay

Temp Sensor

FIB

ControllableRelay

Temp Sensor

ESS

Controllable Relay

Temp Sensor

SC

Temp Sensor

RPI

ManualSwitch

TempSensor

Safety12VLoop

HV Relay

HV Relay

SafetyLoop

Ground FaultMonitor

System12V

HV Relay

12VDetection

12VDetection

RPI

ESS

HVfrom PV

+

-

GroundFault Monitor

HVIsolation Relay

+

Safety 1212V

All Subsystems(Jumper Cable)

Safety Reset Button (Green)

Shutdown Button (Red)

Temperature-Controlled Switch

+

System 12V

HVIsolation Relay

+

System 12V from ESS

FaultIndicator

Temp Controlled Switch

Controllable Relay

Safety Relay

ESS

RPI

HVfrom PV

+

-

+

System 12V from ESS

GroundFault Monitor

+

Safety 1212V

All Subsystems(Jumper Cable)


Shutdown Button (Red)


+

System 12V

HVIsolation Relay

HV To ESSvia SC

HVIsolation Relay

HVIsolation Relay

HV from PV& to FIBvia SC

HV fromPV & ESSvia SC

Switches

SC

SIB

FIB

Controllable Relay

Temp Controlled Switch

HVto/from ESS

HVfrom RPI

HVtoFIB

FaultIndicator

Safety Relay

SC

RPI

ESS

SCADA/SIB

FIB

HVfrom PV

+

-

GroundFault Monitor


Manual Trip (red)


Safety 12"

Safety Loop

HVIsolation Relay

Safety Loop Return

Safety Loop

System 12Vfrom ESS

Safety Relay

Safety 12"

Safety 12"

HVIsolation Relay

Switches

HVIsolation Relay

Safety Loop

HVto Output

lafayette photovolt aic research and development system 2010

Documents

development system

system integration

energy storage system

ac conversion system

photovoltaic power

photovoltaic array

various project requirements

dozens of project requirements