application of microcontroller in windturbine system
TRANSCRIPT
-
7/31/2019 application of microcontroller in windturbine system
1/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 1
FUSE DEMONSTRATOR DOCUMENT - 123
Application of Micro-controller to Wind Turbine System
Abstract
Proven Engineering Products Ltd. is a mechanical engineering company with facilities for
machining, welding and plastics formation specialising in renewable energy sources. The
objective of the project was to improve the human interface and control features of the well
established wind turbine system for off grid power supplies with micro-controller
technology. The introduction of microcontroller technology will enable a gain in market share
and the knowledge transferred into the company to allow further development and new
products. The applications for wind turbine system are in remote houses and farms,
telecommunication sites, etc. both in the UK and world-wide for the generation of off grid
power.
The renewable energy market is growing, and in order to sustain growth and competitiveness,
Proven needs to make its wind turbine system more user friendly; more capable and
adaptable, and to provide customisable features for the growing market. Our present system
is not customisable and requires costly factory set up procedures of many potentiometers
and other discrete components. The user has a tendency to modify the settings in the field
which most often require the unit to be returned for calibration. With the micro-controller
controlled system set up procedures for the user to operate can be included and Proven
expect to gain market share by supporting extra features. There is also an emerging market
from the industrial sector that demands extra features from such equipment that must becustomisable from installation to installation. This can only be done by the use of electronics
more advanced than discrete components. This represents a major leap in technology for
Proven Engineering Ltd. who are a mainly mechanical engineering company.
There are two main types of wind power systems. The first is a simple system which
supplies a simple load for water heating for example. In the second more complex system the
wind turbine charges a bank of batteries whose dc voltage can then be converted into domestic
230V ac power. Presently the present system requires two systems, however, with the
microcontroller system both types can be incorporated on the same board and even integrated
to work together where appropriate.A user interface via a keyboard and LCD status display is included in the new microcontroller
system. The existing system provides only very crude load control with difficult to use and
adjust analogue monitoring circuits. There is no friendly user interface either for the input of
information or for display.
The cost of the experiment was ECU 47k and was scheduled to last for 14 months. The
duration of the actual project was 18 months, Several issues contributed to this delay which
including the illness of the main engineer on the project and some technical issues with the
project.
The payback period is estimated to be within two years assuming the sales increase as shown
in section 4 and the ROI is estimated to be 400% within a five year period. However, the
-
7/31/2019 application of microcontroller in windturbine system
2/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 2
microelectronics unit only represents 5% of the selling price of the completed wind turbine
system and the relationship between this project and increased sales is complex. Since it is a
part of a system in a developing new market - the project will both increase sales due to
better functionality and user benefits and making it easier to produce in the increasing
production needs.
As can be seen from the figures below in 17, we expect to double our sales next year and
increase thereafter - based on actual orders and enquires - so increasing both turnover and
profitability.
There were many lessons learned during the project, with perhaps overcoming the fear of new
technology with help and support being the greatest; and the choice of micro-controller that
best suited the expertise of Proven and the application. There are perhaps lessons to be
learned for the microcontroller industry as well - more work needs to be done to enable small
non-electronics companies like Proven to easily assimilate and use microcontroller technology
in their products.
Another major lesson was the need for detailed planning at the start of the project and
accurate monitoring throughout the duration of the project.
There are several routes to economic benefit from the project.
Reduction of overall system cost.
When an integrated inverter module is included there will be a significant ( ECU2500
)reduction in system cost so making sales easier in a capital cost sensitive market. This will
also allow in house manufacture of more of the system rather than import from the USA.
Reduction of circuit board stocks.
Presently two very different boards are used with different assembly and set up needs. Themicrocontroller system will have only one board for all functions. Combined with the increase
in sales this will for the first time allow sub contract board manufacture in economic batches
so cutting costs and improving quality.
-
7/31/2019 application of microcontroller in windturbine system
3/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 3
1. Company Name and Address
Proven Engineering Products Ltd.
Moorfield Industrial Estate
Kilmarnock
Ayrshire
KA2 0BA
UK
Telephone: +44 (0) 1563 543 020
Fax: +44 (0) 1563 539 119
E-mail: [email protected]
2. Company Size
The company comprises 12 full time employees and 5 part time. There are three people
within the company who have some electronics expertise, this is focused upon simple power
electronics with some analogue design.
The people involved in the project were Gordon Proven who has a mechanical engineering
background but some expertise in discrete analogue electronics.
Richard Curtis and Richard Caldow both of whom had a small amount of expertise in digital
electronics using 74C and CD4000 series CMOS.
3. Company business description
Proven Engineering Ltd is a small independent multi-discipline company with facilities in
house for machining, welding, plastics forming, permanent magnet generator construction and
basic electronics. Provens main business is in mechanical engineering, manufacturing metal
products but we have developed expertise in process control and automation and have
developed our own wind turbines using our novel design of turbine blades. Proven
manufactures and installs the wind turbine systems which include all the metal work, wind
turbine blades, battery and inverter and controller. Only the batteries and inverter are bought
in from a third party. These systems are mini power stations for use in remote locations such
as houses, farms, remote phone systems, remote water pumps, etc. They require their own
power control and management system and it is this that the project concentrates upon.
These systems are bought individually by the users.
4. Company Markets and competitive position at the start of the project
Proven is operating in a growing World market. We have 90% of the UK market in our size
range; and a growing World reputation for wind turbines which are tough and reliable. We
have only a few competent world competitors - Bergey of the USA being the most
significant. More competitors are emerging and the market is simultaneously expanding
rapidly. To stay competitive we have to provide better functionality - especially in Hybrid
systems (e.g. Wind Solar Hydro combinations) and lower costs. Without the FUSE project
the Proven controller would be seen to be less attractive when compared to our competitors.
This would limit the long term growth of the company and without the new controller sales
-
7/31/2019 application of microcontroller in windturbine system
4/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 4
would less quickly.
Proven Wind Turbine and Renewable Energy Sales
Year 92 93 94 95 96 97 98 99Number of Units 1 16 10 14 22 30 44 95
Sales Value ,000s 5 72 52 84 175 217 330 855
Value for 98 extrapolated from first 9 months
Value for 99 based on order book and known sales in pipeline.
Gordon Proven
Year
9293
9495
9697
9899
Number of Units
Sales Value ,000s0
100
200
300
400
500
600
700
800
900
Year
To convert to ECU the above figures should be multiplied by 1.5.
Proven Engineering has been designing and building special machines and automatic control
systems since 1980, and developing small wind turbines (600W to 6000W) since 1981. The
Wind turbines have been on the market since 1992 and there are now over 150 systems
installed world-wide. These are mainly in the UK but with several installed in the Falkland
Islands (over 20 turbines) and South Africa. Other machines have been sent to sites including;
Eire, Ethiopia, New Zealand, USA and Japan. During these early years the Wind turbinesystems have been adapted to improve customer needs using feedback from existing
customers.
The main market to date has been from domestic users but there is a growing demand from the
industrial field. An example of this is the increasing need for more mobile phone transmitters.
These transmitters are being installed in more remote sites as the phone companies strive to
increase the service areas. It is frequently impractical to bring mains power to these sites and
as they are often exposed hill top locations they are ideal for using wind generated power.
Other industrial situations include radio links for conventional telephone systems where the
terrain prohibits the use of cables. The domestic market tends to be cost sensitive and the
industrial sector is looking for reliability and how the system will function within theirexisting equipment. The industrial sector often requires the inclusion of certain specifications
-
7/31/2019 application of microcontroller in windturbine system
5/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 5
and system operation which may be slightly different than normal. The present equipment is
therefore ruled out of this latter market since it is of fixed operation and not easily
customisable. It is believed that market share can be gained by the inclusion of more features
since customer feedback suggests that it is the features that can tip the balance from a non sale
to a sale.
This year two of the major UK mobile phone companies have opted for Bergey (USA) wind
turbines - in preference to Proven due, we think, to us not being quite ready with our
technology for that market. We are expecting to install a test system with one of the other
companies (One to One) in the next few weeks. The introduction of the microcontroller based
system will allow us to become competitive with Bergey.
5. Product to be improved and its industrial sectors
The product to be improved is a wind turbine system controller. Below is shown the PCBs of
the existing controller with the sixteen adjustable potentiometers.
Figure 1 shows a block diagram of the
existing system. The three phase
output of the wind turbine1 is
rectified to give a dc voltage which is
then used to charge a battery bank.
The analogue circuitry monitors the
battery bank and, as this becomes
fully charged, switches in a load to
divert power from the wind turbine,
therefore controlling the amount of
charge into the battery bank.
In periods of time when there has
been little wind or when the demand
for power has been high then the batteries will become discharged. In this case a backup
power source is usually available. This is often an engine driven generator. In many cases the
generator will be automatically started before damage to the batteries through overdischarge
occurs.
The power stored in the batteries can be used directly (e.g. to provide heat through a resistiveheating element) or the dc voltage can be converted into a mains ac voltage by means of an
inverter.
1The output voltage of the Windturbine is low voltage three phase. The magnitude depends on the system
battery configuration voltage which is normally 12, 24 or 48 V for battery systems and 120 V or 240 V heating
-
7/31/2019 application of microcontroller in windturbine system
6/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 6
Battery
Store
DC Divert
Loads
WindTurbine
3ph LV out
Analogue
ControlCircuit
AC Divert
Loads
Rectifier
Inverter
RelaysContactors
Backup
Generator
Charge
ControlContactors
230VacOut
Figure 1 Block diagram of existing system
The wind turbine system can be used for any low power application where mains electricity
is not available such as remote houses, farms, telecommunication sites and third world
applications. Many customers with an existing electricity supply and a good wind resource
install a system to offset the amount of conventional power used. This has both
environmental and economic arguments.
The electronics within the present system are realised by analogue designs using discrete
components and adjusted by means of 16 potentiometers which have to be set separately for
each board produced. This setting is time consuming and requires the use of a bench power
supply which can be accurately set to the required switching levels. This makes it difficult to
accurately adjust the switching levels in the field and virtually impossible for customer
adjustment. However end users have wanted to adjust the levels and attempts have resulted in
the need to return the control board for factory resetting.
System information is shown to the user via a series of board mounted LEDs and two
analogue moving coil meters. These LEDs indicate the state of the contactor and relay
switching signals, the meters show battery voltage and charging current.
There are several reasons to innovate these are:
To be able to compete with our competitors and improve our market share.
To be able to reduce assembly and setup costs.
To reduce cost of the electronics and to contain all the electronics on one board.
To provide digital user control eliminating the use of potentiometers as stated above.
To enhance the product by improving the existing functions and features.
To make the unit more user friendly by providing a comprehensive user display and input
keypad allowing extra features.
Using a micro controller with an analogue to digital converter will allow the switching levels tobe set in software and the inclusion of a LCD display will allow more system information
-
7/31/2019 application of microcontroller in windturbine system
7/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 7
including power etc. to be displayed accurately and replace the two moving coil meters thus
reducing the production cost.
6. Description of the technical product improvements
LCD Display
Power Supply
Key
PadReal Time
Clock
Oscillator
Analogue
Processing
OutputDrivers
PIC 16C74Analogue
Signals
(Battery
Voltage,
Current)
Serial
Interface
PWM signal for
proportional loadcontrol
Generator Start
Load Switching
EEPROM
Figure 2 Block Diagram of Improved Product
A diagram of the improved system is shown in Figure 2.
Photograph of the
microcontroller WT
controller with keyboard
and LCD display in final
prototype form.
6.1 Structure ofhardware and software
The structure of the software of the improved product is shown in Figure 3. Each of thesoftware modules interface to a central main programme core. This structure allows individual
-
7/31/2019 application of microcontroller in windturbine system
8/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 8
modules to be customised and improved with out modification to the main programme or
structure.
Clock, etc.
Main
Program
EEPROM
I2C
Keyboard
Signal
Processing
Voltage
Power
LCD
Display
Current
PWMOutput
DigitalOutputs
Generator
Logic
External link
Figure 3 Program Structure
The targeted aims for the new product were met and have resulted in a significant
improvement in the control electronics of the wind turbine.
The equipment is now much more user friendly by the inclusion of the keypad and the LCD
display. With a basic keypad some user control of the system is possible. This includes theadjustment of the switching levels from the factory set values. These levels will be shown on
the display. This adjustment will allow the user to safely fine tune their system to give the
best performance; but by limiting the access for adjustment by the microcontroller potentially
damaging adjustment is not allowed.
The main effect for Proven, however, by the use of the keypad is the reduced test and setup
time in the factory for the wind turbine controller thus reducing manufacturing costs.
The method of charge regulation has been improved with more control over the divert loads.
The present controller switches in a series of fixed loads. It is preferable for the divert load to
be gradually increased or decreased, this has been achieved by the use of a single element with
PWM power control. This smoother control is better for the health of the batteries.At present each divert load step is controlled by a separate transistor drive and relay.
Hence the cost of the electronics has been reduced, fewer components are used so the control
electronics now fit on one board reducing the inventory costs and increasing the systems
reliability.
Extra outputs have been made available to allow extra features to be added in future models.
One such feature is the ability to start and stop a backup generator another is a switched
output to provid a warning of low battery condition.
-
7/31/2019 application of microcontroller in windturbine system
9/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 9
7. Choices and rationale for the selected technologies, tools andmethodologies
Several technologies were considered that could be used to upgrade the Wind Turbine System.
The main areas of consideration were the effectiveness of the technology chosen, the cost of
the technology compared to the predicted sales volumes and the application of the technology
to future product development within the company. Although the unit is not particularly
price sensitive it must always be borne in mind that the typical customer of this equipment is
buying to a budget and hence price considerations are important. The customer must always
see value for money and any price increase must be matched to the extra features provided.
Advice was taken from Paisley University who conducted a feasibility study into the
available technologies, such as discrete devices, FPGAs, ASICs and micro-controllers.
Discrete The product could continue to be developed using discrete devices, but there is a
very limited scope for improvement. This methodology would greatly increase the
component count and so result on a much larger and costly PCB. The increased componentcount also affects the final reliability of the product. One of the main problems with the
discrete system is the difficulty in adjusting the potentiometers which set the switching and
hysteresis levels. Expanded displays can not be achieved using discrete components
considered essential for the improved device. New features could also not be handled without
a complete redesign of the system.
PLCswhich are easy to program were also considered but were deemed to be too expensive
for this equipment. A PLC controlled wind turbine system has already been built by Proven,
but it was found that the cost was very high, a typical PLC with analogue inputs, costing
almost 1,000 ECUs. This design was too costly for the domestic user Although extremelyversatile in industrial control applications attempts to use PLCs in the past for wind turbine
control applications have not be favourable. Several external components such as a display
module would have to be included in the system further raising the cost of the finished unit.
Features such as PWM control would also need to added. The power requirements of the
devices also need to be considered. We need a system with minimal power consumption
especially in the smaller systems as every watt used by the controller needs to be produced
by the wind turbine. PLC tend to assume that there is a mains power supply available.
FPGA products are suitable for handling concurrent tasks quickly which is not a requirementof the Wind Turbine System. Additionally, several supporting devices would be required to
complement the FPGAs lack of in-built peripherals which would lead to a high unit cost.
Since a real time clock is used in the system a communications protocol would have to be
developed which not best suited to FPGAs. There would be a steep learning curve associated
with the implementation of this technology in this application resulting in an excessively long
time to market.
ASIC products were examined, but ruled out due to both the high tooling costs and high unit
costs for the volumes considered. Risks are also unacceptably high presenting a very steep
learning curve for this technology.
-
7/31/2019 application of microcontroller in windturbine system
10/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 10
Micro-controllers Although micro-controllers are relatively slow devices in comparison with
FPGAs, they function best in a serial application environment, such as the Wind Turbine
System. The micro-controllers have in-built peripherals and are available from a wide family
of compatible devices they also have dedicated serial bus I/Os allowing interface to a wide
range of serial peripherals e.g. memory, real time clocks etc.. Moreover, the unit costs are low
and the perceived implementation speed is higher than with other technologies. The Paisley
University feasibility study also concurred that the micro-controller would be the most
suitable technology for this application.
Several micro controller families were initially considered and development began using the
Thompson ST6 family. This family met all the hardware needs required for the planned
product. These included analogue inputs, on chip EEPROM for user parameter storage and a
PWM feature. Another major benefit seen was the availability of a high level graphical
programming aid called Realiser. This allowed the required design to be entered in a schematic
form and then a complete programming code file is generated ready for downloading to a
specified Thompson micro controller.
Proven were concerned that knowledge transfer should take place but being a small company
it was only possible to dedicate one employee to the main programming aspects of the
project. As the knowledge gained would be lost if that employee left the company, the
deciding factor to choose the Thompson ST6 was that it could be programmed easily by the
use of the Realiser software package, and so any of the engineers in the company could easily
acquire the knowledge needed to use and maintain the system.. It was also felt that code
changes after a length of time would be easier if they were made to a schematic rather than
following thorough a program listing. This program listing possibly originating from anotherperson.
To produce a programming file from the Realiser the user simply draws the required system
from a library of logic functions, timers, counters, etc., and indicates which pins of the micro
controller are connected to the various inputs and outputs of the schematic. The software
allows the circuit to be simulated and tested with a range of virtual instruments and at the
press of a button produces the required programming file. Using this software package meant
that in a very short time a first micro controller board was built which replicated all the
functions of the existing controller.
One of these early ST6 based boards was incorporated into a wind turbine system and
installed in a customer application. This controller has been working without a problem sincebeing installed.
However, it was discovered that it is very difficult to represent some of the required
functions in a schematic format, for example initialisation of the LCD display but only once
when the program began.
At this time in the project Paisley University (the TTN) was attended for a course in LCD
displays. This was the first formal training undertaken. On the course the Microchip PIC
family was introduced. The instruction set for these microcontrollers was fairly simple to
learn and it was discovered that there was a wealth of information from the manufacturers and
also many third party sources.Following the course it was decided to focus the design on the PIC microcontroller family.
-
7/31/2019 application of microcontroller in windturbine system
11/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 11
As the micro-controllers form a significant part of the control PCB, which was designed and
made in-house using the layout package EasyPC, initial testing was carried out after the PCB
had been populated and assembled. This included basic functionality testing by means of a
small test rig at an electrostatic-free workstation.
Final testing was carried out on the fully assembled unit operating in a diagnostic test
sequence
8. Expertise and experience in microelectronics of the company and thestaff allocated to the project
The electronics expertise with Proven Engineering at the start of the project was limited to the
design and assembly of discrete circuits and some expertise in the programming of PLCs.
Three Proven staff were allocated to the project - Two with Mechanical Engineering degrees
and one with an Electrical HNC. All have experience in the Renewable Energy Field and are
familiar with the requirements for the Control system.
Although discrete analogue electronic controls had been developed and used over several years
there was no-one in Proven with the appropriate knowledge or experience to enable a move
into Microcontroller technology with the complex real time feedback control systems needed
for effective system control and stability.
Several attempts to assimilate and master micro processor technology had been made in the
past but without result.
9. Workplan and rationale
The work plan and effort in person days together with estimated costs is shown below. The
first table below indicates the effort and costs, both planned and actual and the other the
schedule that was planned in the original Technical Annex before the start of the Application
Experiment. Due to illness and some design changes the project needed to be extended by four
months, this is reflected in the extra time spent on the management and design of the wind
turbine system.
Estimated Actual
ActivityEffort in persondays Costs
kECUs
Effort inperson days
Costs
kECUsManagement 39 6.0 45 8.7
Training 20 8.5 23 8.0
Specification 34 6.4 44 5.7
Design 56 10.7 94 12.3
Evaluation 85 16.0 96 12.5
-
7/31/2019 application of microcontroller in windturbine system
12/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 12
The original workplan is shown below.
Activities Month1 2 3 4 5 6 7 8 9 10 11 12 13 14
Management
Project Management X X X X X X X X X X X X X X
Specification
Functional Spec. X X
System Spec. X X
Technical Spec. X
Training
Micro-controller Training X X
Design
System Level X X
Sub system Level X X X X
Evaluation
Prototype Production X X X X X X X X X
Test set up X X X X
Functional Test X X X X
Prototype Test X X X X
Field Test X X X X X X
Approval was sought and authorised for the experiment to be extended by 4 months due toillness and the extra time needed to improve the operation of some software algorithms
discovered during the field test stage of the project. This added two months to the project
between months 7 and 8 and months 10 and 11 of the original schedule shown above.
9.1 Management
Management time was allocated throughout the project. The time spent was not only the
regular management of the project but also time allocated to the monthly monitoring meetings
and the preparation of the monthly reports. An extra 6 days were spent on the management
of the project over that planned due to the time extension.
9.2 Specification
The specification of the product was scheduled during the first three months of the project
and a specification was completed in this time frame. The initial plan was to use the ST6
micro-controller from Thompson, the main reason being the associated Realiser software
package that allowed the design to be entered in a schematic form to produce the correct
coding. This micro-controller was chosen since it was felt that this would provide a simple
learning curve for micro-controller technology and contained many in-built peripherals.
However, the Realiser software was limited in the functions it could produce and as a result
of the training undertaken at the University of Paisley a major change was made to the
specification. It was decided to use PIC micro-controllers for all of the design. This is
explained more fully in the design section. As a result of this change extra time was expended
on the specification in month 8 and 9 extending the specification period by 10 days.
9.3 Training
The University of Paisley provided formal training and some design assistance on the use and
-
7/31/2019 application of microcontroller in windturbine system
13/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 13
operation PIC micro-controllers. The training, tailored to Provens needs, focused upon the
programming and features of PIC micro-controllers since this was the now chosen micro-
controller to be used in the wind turbine project.
Three Proven staff attended the Paisley training programs.
The training comprised of one two day course and two three day courses early in the project.
The two day course was an introduction to developing PIC based micro-controller products.
The two three day courses focused upon driving LCD modules by the micro-controller and
the serial bus operation of the PIC Micro-controllers.
Informal training was undertaken separately by extensive use of published literature and data
CD Roms. Arizona Microchip, the manufacturers of PIC micro-controllers also have a
comprehensive web site containing many worked examples of typical programme modules.
We also had contact with two other FUSE project teams to discuss issues and ask advice.
9.4 Design
The design section of the project was extended due to several reasons the primary one being
the change from the SGS Thompson Microprocessor to the Arizona Microchip PIC micro-
controller. The changes to the specification have resulted in what we believe to be a much
better product.
Also during the actual field tests ( as opposed to simulated testing ) it was found that some of
the control algorithms were not able to cope with the constantly varying input from the wind
generator. These had to be refined and added to the time. Time was also spent upon the
analysis of an inverter module. This activity although extending the time spent on the design
phase of the project, has enabled us to gain valuable knowledge of inverter technology and
operation allowing the accurate specification and purchase a commercial inverter that meets
the requirements of the wind turbine operation.
The load control has been refined so that in place of the regulating inverter module the micro-
controller now uses its Pulse Width Modulating functions to control a pulsed DC system.
This is integrated into the system rather than being a separate controller as previously
envisaged giving much greater control of the loads. This was not in the original specification
but was included as our knowledge increased regarding the features and operation of
microcontrollers.
The printed circuit boards were manufactured in-house using single sided copper board to
reduce the costs. It is planned to have these professionally made for the production machines.The costs of the design exceeded the original estimate due to the change in microcontroller.
Some cost were, however, saved since the design of the inverter module were not persued.
9.5 Evaluation and Testing
As shown in the software programme structure the wind turbine controller was developed in
a modular fashion. As each module was designed and the software developed the hardware
and software of the module was thoroughly tested and correct operation verified.
On the bench with test equipment it is possible to simulate instantaneous operation but in
real life the wind which drives the turbine is never constant and hence the controller is dealingwith a constantly varying input that is impossible to simulate with bench instruments.
-
7/31/2019 application of microcontroller in windturbine system
14/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 14
Throughout the duration of the project, development has continued using two prototype
boards. One of these has been used with the emulator for bench testing. The other has been
installed within a wind turbine system at the Proven Engineering factory. This has allowed
ongoing testing with a real system as soon as a new section of code or circuit has been
completed. The testing of the code has been completed with the watchdog feature of the
micro-controller inhibited enabling all faults and software problems to be monitored by
disallowing the micro-controller to enter its reset routines if a fault is detected.
During this extended testing in real wind conditions as described the software algorithms had
to be fine tuned to cope with the constantly variation of the wind. These tests could not be
done on the bench and are necessary since the welfare of people and the successful operation
of remote repeater stations need to operate with minimum maintenance because of their
remoteness.
Evaluation time of the product approximated the time planned in the original proposal.
10. Subcontractor information
University of Paisley,
High Street,
Paisley,
PA1 2BE,
Scotland
Phone (44) 141 848 3419
The University of Paisley was chosen as the training subcontractor because of its closeness to
Provens premises (only 30 Km from Provens premises) and for its ability to tailor courses
to the specific companys needs. The costs were also competitive. All thses matters regarding
the content of the courses and the costs were discussed and a contract written and signed
covering all the relevant points before the training commenced.
The training focused upon the programming and features of PIC micro-controllers since this
was the chosen micro-controller to be used in the wind turbine project.
The training comprised of one two day course and two three day courses early in the project.
The two day course was an introduction to developing PIC based micro-controller products.
The two three day courses focused upon driving LCD modules by the micro-controller and
the serial bus operation of the PIC Micro-controllers.
Design assistance was also provided by the University of Paisley.
EMC Compliance Services
15 Hal Road
Nemphlar
Lanarkshire
ML11 9JE
This subcontractor was used for design assistance and advised Proven on our design with
reference to compliance to EMC regulations.The circuit and its operation were reviewed by EMC Compliance Services for problems who
-
7/31/2019 application of microcontroller in windturbine system
15/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 15
advised on minor changes in PCB layout etc. No formal testing for EMC compliance was
performed since this will be done on the completed unit. No charge was made for this EMC
design advice.
11. Barriers perceived by the company in the first use of the micro-controller
technology
The main barrier perceived by Proven was the knowledge barrier. The electronics experience
in-house was only concerned with simple discrete circuits. There was no knowledge of digital
electronics and hence how to develop a development schedule for a micro-controller.
However, Proven knew that the knowledge of digital electronics would enable them to
produce products to serve many different applications related to renewable energy and so felt
that to subcontract the design would be the wrong thing for them.
The initial choice of micro-controller was influenced by this gap in knowledge since we felt
that we should use the simplest method of data entry and this seemed to be provided by the
ST Realiser system. This micro-controller also had a number of built in features not available
with other products, although able to be added using external components utilising the serial
bus.
Since Proven sells the wind turbines in very low volumes it is difficult to use contractors for
the electronic assembly. A subcontractor minimum assembly run could provide the
electronics for well over a years production causing cash flow problems. The result is that
subcontractors for assembly can not be used and Proven must acquire these skills of assembly
and microcontroller development.
There was also a financial barrier which prevented Proven launching into the unknown,
however, we did believe that we needed to make a leap in technology to keep our products up
to date. If this did not happen then Proven would be more reliant upon their metal work
skills, this would hamper growth of the company and make our products less competitive in a
rapidly developing market.
12. Steps taken to overcome the barriers and arrive at an improved product
We at Proven knew that the wind turbine system had to be improved to enable our market
share to grow and to be able to provide features to ensure its long term sales. Several years
ago we approached the Department of Applied Physics at the University of Strathclyde who
conducted a feasibility study concluding that the microprocessor technology could be used in
an improved wind turbine. Several years later we heard about the FUSE programme through
advertising by the TTN and we contacted Paisley who did another feasibility study. Because
of the great advances in micro-controller technology Paisley we were convinced that micro-
controller technology was the most suitable for the wind turbine project. Several other
technology options were considered.
The structured approach taken in developing the Fuse proposal which included the detailed
project plan gave us further confidence that we could complete the project and its detailed
approach allowed a costed plan to be developed. Within this plan the ROI and paybackperiod for the investment were also calculated. This further gave us confidence that the
-
7/31/2019 application of microcontroller in windturbine system
16/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 16
project should be completed using microcontroller technology.
A training was also developed which not only included formal training and design assistance
but also included the use of the Web for information and access to other independent experts
who could go into more detailed training on the specification and design of high current
equipment.
The financial support that the Fuse programme provided was very important and this
removed the financial barrier although we now see that we will be able to recover the cost of
the development relatively easily with the increased volume and selling price of the wind
turbine with the extra features.
Throughout the project we also found networking with other First Users useful in giving us
insights into others experiences etc.
13. Knowledge and experience acquired
The main area of experience gained is in managing a complex project involving microcontroller
technology at the core.
The training courses were of great help in acquiring the technical skills quickly. We now have
the capability to specify and design micro-controller projects using the knowledge we have
gained from this FUSE project. This has already been shown by our first replication project
using a micro-controller. This is an automatic start for a diesel generator which is incorporated
into a micro hydro power installation.
The involvement with the electronic peripherals including LCD displays, keyboards, memory
and serial busses has generally updated electronic skills. Whilst sourcing these parts from
technical catalogues and journals other equipment and information was discovered which has
been useful in other areas. The above training and experience equips us to define and develop
microelectronic projects for the future growth of the company.
Our design skills have been enhanced through our attempt to design the inverter and a better
working knowledge of power electronics has been gained including the use of IGBTs.
Although the final use of power electronics in the project has been limited to the PWM
switched load, the early experiments and investigations into IGBTs has led to these devices
being used as a replacement for MOSFETs in the Proven Wind Turbine heating controller.The IGBTs are considerably less expensive than the previous devices used and have proved
over a 12 month period to be greatly more reliable increasing our competitive position.
Through the use of the PCB layout package EasyPC we are now able to manufacture our own
PCBs. This package, EasyPC by Number One Systems Ltd., is only a simple design package
but it has enabled Proven to develop our own prototype boards saving development costs.
We do plan for the final production unit to have the board professionally made by a local
PCB supplier. The manufacturing contract is being developed and training and experience the
FUSE project has given us in dealing with subcontractors gives us confidence to use such
subcontractors.
-
7/31/2019 application of microcontroller in windturbine system
17/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 17
Most gratifying to Proven was the fact that we have been able to complete this project using
totally new technology to us with the training and design assistance suggested in the original
plan.
14. Lessons learned
Many lessons were learned throughout the execution of this project. A surprising number
from going down paths that did not go anywhere but introduced us to other aspects of
electronics that was beneficial to the overall project and to our present products providing
greater reliability e.g. the use of IBGTs.The instruction set for these micro-controllers (PIC) was fairly simple to learn and it was
discovered that there was a wealth of information from the manufacturers and also many third
party sources.
Microchip provide a CD-ROM with comprehensive device information and large library of
applications and examples which has proved a great help and is recommended for all users.
They also provide a good telephone technical help line. This helped us, with training, to use
assembly language programming of microcontrollers. Micro-controller technology, with the
correct guidance, can be adopted by companies who have little electronic engineering
knowledge; but a great deal of time and expertise had to be acquired before we could achieve
the complex control systems we needed.
The time required for software development should not be underestimated, sources of good
examples of coding can be found by using the Internet. The knowledge on how to use a micro
can be fairly quickly obtained but coding can take a lot of time.
There are discussion groups where solutions to frequently encountered problems can be
found. These are published on Bulletin Boards where examples of code are also posted.
Good early planning is essential to make the best use of the micro controllers features, but of
course until the capabilities are well known this is not always possible, this is where early
design assistance and training is most useful. Care and consideration is necessary in the
selection of the function of each I/O pin to optimise the function and minimise coding
changes.
An example of this was the use of two I/O pins for the inclusion of a watch crystal so thattime counts of several seconds could be achieved. Using the internal microcontroller clock it
became difficult to set a counter to measure times of more than fractions of seconds.
From application notes it was seen that with the addition of a watch crystal one of the
internal timers could be set to measure periods of several seconds. This crystal required the
sacrifice of two particular I/O pins. These pins were being used for other purposes and
therefore the code had to changed. At this point in time all the I/O allocation was reviewed
and changes were made in several sections. These changes were possible as the final hardware
layout was not fixed. If we had been at the stage where a hardware layout had been finalised
then we may not have been able to use the timer controlled by a second crystal. A software
fix could have been made but would not have been the simplest solution.The above example was the result of continuous learning and not just down to poor initial
-
7/31/2019 application of microcontroller in windturbine system
18/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 18
planning. On the more complex micro controllers there are so many inbuilt features and
functions that it is difficult for a first user to incorporate them into the initial design. As time
passes something may be discovered in an application note which has a beneficial effect on
other parts of the project. With the knowledge gained this situation should not occur in any
future new products.
Towards the end of the project the engineer associated with the software of the project left
the company. This was a big blow since we had invested a large amount of training in him. We
can not stop anyone leaving the company to go to another job but we could have written into
his contract that a proportion of training costs should be repaid if should he leave within a
certain time of completion of courses. This repaid money could then be used to enable
training for replacement engineers, thus providing a saving on our costs.
A major lesson was the finding that the Realizer software that was provided with the ST6
microcontroller was not adequate for the total projects needs. By taking advice and attending
training courses the fact that the project could be completed using the PIC family of
microcontrollers was established. A great benefit which speeded up the design and
development process was the purchase of a PIC emulator. Without it written code had to be
loaded into the PIC16C74 available in EPROM style so each modification required UV
erasing. This process is slow and although emulators are relatively expensive the time saved in
not having to erase EPROMs and being able to debug code while it is running in real time
while running the hardware makes them invaluable. Programme changes can be made in
seconds compared to up to half an hour without it.
It had originally been planned that at the outcome of the project we would have developed an
integrated inverter module controlled by the system microcontroller.From the reading of text books on the subject of power electronics this looked perfectly
feasible. However as time passed it was discovered that this area of electronics was not quite
so easy to put into practice. Further reading of manufacturers data sheets and technical
journals led us to the conclusion that physical layout of the circuits is critical for reliable
operation. This physical layout appears to be of such importance that some suppliers of
power electronic devices will freely issue a printed circuit board design to incorporate into the
users own design. Careful consideration needs to be given to track layout, interconnecting
wires and placement of the switching devices on heatsinks.
The above problems and the need for very expensive test and safety equipment necessary for
the high currents and voltages of the inverter caused us to rethink our strategy. This led us tomake the decision that this area of electronics was something best left to those with specialist
training and equipment.
The knowledge and experience gained while investigating inverter design has not been wasted
since it has allowed us to define our requirements accurately and has allowed us to find a local
company who currently manufacture a suitable product. They are willing to work with
Proven to produce a modified version to meet our particular needs.
15. Resulting product and its industrialisation and internal replication
The prototype is currently made up of two separate single sided PCB boards made in houseby Proven. For the production unit these two boards will be combined into one PCB
-
7/31/2019 application of microcontroller in windturbine system
19/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 19
produced by a local PCB manufacturer. The boards will have extra ground planes for reduced
noise and more layers to assist in the PCB assembly.
The microcontroller based board, built in batches of 50 100 by the subcontractor, actually
contains more components and will be slightly more expensive in component cost than the
existing board in the Wind Turbine Controller. However, the use of a specialised
subcontractor will result in a cost reduction of about ECU25 per board (out of ECU90) and a
good increase in quality as well as functionality compared to the present board which is made
and assembled in house. Reliability will be greatly enhanced by the removal of the
potentiometers and having the controls set digitally by the microcontroller programme.
The final product will be fitted into the existing switchgear cabinet. The industrialisation cost
is confined to the cabinet modifications only since the microcontroller replaces existing
electronics. The total cost of these modifications will be less than ECU500. There will also
be an added cost of reprinting brochures to include the extra features of the system. The cost
of this, for the first run, is estimated to be 600 ECU. This work will be complete early in
1999 and the first Wind Turbine with the new microcontroller board is expected to be
shipped during Quarter 2 of 1999 six months after the completion of the FUSE project.
Our ability to offer a many function controller which efficiently takes control of the entire
local power management gives us a better capability than almost all of our competitors. This
can open up new applications such as: control of Diesel Generators and with the use of
ancillary inputs can operate Solar PV etc.. The system also gives historic information useful
to the user and to Proven. Since the complete control of the system makes life much easier for
the end user we expect our competitive position to improve as the market matures.
Using the micro-controller as the core of the equipment it is possible to include features for
individual users but since this will only involve the software no changes to the hardware will
be necessary. It is also planned to investigate further features that would be desirable to have
to enable the development of a range of related products that could be offered at an enhanced
price structure.
The knowledge gained of using microprocessors will not only be of use to this project. Many
other applications have already been identified.
The controller has been designed with some element of flexibility to allow for a degree of
customisation should a customer require.Examples of special needs requested in the past include:
An extra input to generator start signal that prevents the generator starting at the normal
low battery level. Generator only allowed to start before the batteries reach a level where
damage will occur. This feature was specified for an Ecology monitoring project where the
exhaust fumes from the generator engine would affect data readings.
A system that provided power in a youth hostel needed to shut down low priority loads
as the batteries became low. Visitors to the hostel do not always realise that the amount of
electric power was limited when there was no output from the wind turbine. If too many
lights were left on and the stored power became low then the lights would be made
unavailable. Power was still available to the warden and for the fire alarm system.
-
7/31/2019 application of microcontroller in windturbine system
20/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 20
The above features could all be incorporated by using spare inputs with some software
changes. Previously they would have to be added in using separate control boards based on
analogue and digital discrete circuits.
It is not planned to customise every system but, by including some general purpose
input/output lines, special needs can be met by software change only.
The first new project using microprocessors has already been completed. This is an add on
control to an existing hydro turbine installation. The control utilises routines written for the
fuse project to activate and monitor a specially converter diesel generator.
The development is underway for a hydro turbine using the power of a stream instead of the
wind to provide power. The controllers of the two systems are very similar and this range of
equipment will use the hardware and several software routines developed for the wind
turbine.
16. Economic impact and improvement in competitive position
This project associated with the FUSE scheme was a small component in a large system.
The FUSE Project does not result in a less costly product but it provides Proven with a
greatly enhanced competitive position.
As can be seen from the table below sales have been steadily increasing. The average cost of
the whole system is approximately ECU12000 with the microcontroller electronics
consuming approximately ECU200. Without the use of microcontroller microelectronics
Proven would not be able to compete effectively with their competitors, this would result in
declining sales culminating in Proven Engineering going out of business. The FUSE projectwas crucial to the survival of the company.
Year 1995 1996 1997 1998 1999 2000 2001
Units 14 22 30 44 95 135 180
Sales value (ECU 000) 122 263 325 495 1382 1600 2600
It is very difficult to calculate the ROI since the cost of the electronics within the FUSE
project is so small when compared to the selling cost of the overall system. There is a general
increase in renewable energy sales and the increased functionality of the micro-controller
system will help to reinforce extra sales which are projected to be over 200 units by the year2002.
The payback period is estimated to be within two years assuming the sales increase as shown
above and the ROI is estimated to be 400% within a five year period. However, the
microelectronics unit only represents only 2% of the selling price of the completed wind
turbine system and the relationship between this project and increased sales is complex. Since
it is a part of a system in a developing new market - the project will both increase sales due to
better functionality and user benefits and making it easier to produce in the increasing
production needs.
Due to its adaptability the micro-controller system can also be used for our newly developed
micro-hydro turbines. The rapid boom in mobile phone users and the requirement for greatercoverage in more rural areas will also increase sales.
-
7/31/2019 application of microcontroller in windturbine system
21/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
15/04/99 21
17. Target audience for dissemination throughout Europe
Proven Engineering is a small company which has extensive knowledge of their specialised
technology and in building machines concerned with this technology. Although Proven had
used electronics in the past their electronics expertise was limited and restricted to discrete
electronics and very simply PCBs.The four digit Prodcom for Proven is 3110, Electric Motors, Generators and Transformers
and this demonstrator document would be of interest to companies within this code who plan
to use microelectronics to control their systems. However, the target audience for this type of
project covers much more than those companies in this code.
This demonstration document therefore should be aimed at a target audience of companies in
all industrial sectors producing instrumentation equipment and in particular as described in
Prodcom code 3320, Instruments and Appliances for measuring, checking, testing etc..
The demonstrator document should be targeted to companies who tend to be small in size and
who utilise poor methodology in defining and executing projects, often resulting in overruns in
both time and cost. The document also has relevance to companies who are starting from alow electronics expertise base and wish to improve their product.
However, it also shows how a company not involved with microelectronics can use the
technology to their advantage to stay competitive and in business. The target audience for this
project is therefore very large.
The project has particular relevance to companies involved in renewable energy projects such
as the generation of electricity by means of wind or water power. Proven Engineering are
members of the British Wind Energy Authority and members of the Small Wind Energy
Committee within this organisation and plan to discuss the project with them to show thebenefits of electronics. Targeting similar bodies throughout Europe would further expand the
target audience.
-
7/31/2019 application of microcontroller in windturbine system
22/22
Fuse Demonstrator Document - 123 Proven Engineering Ltd.
17.1 Post Script
Unfortunately Richard Curtis - the main staff participant in the programming part of project
has decided to go back to England and leave Proven. Although this will no doubt disseminate
the benefits of FUSE in general terms and his new company will benefit, Proven have to re-
learn some of the training in PICs and train another engineer.This re-inforces the original aim - and the reason for using the ST6 and Realizer - to find an
easily useable microcontroller system which could be used on a casual basis by any non-
expert engineer ( much as PLC systems have become).
Fuse Demonstrator Document - 123 Proven Engineering Ltd.