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Fuse Demonstrator Document - 123 Proven Engineering Ltd.

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FUSE DEMONSTRATOR DOCUMENT - 123

Application of Micro-controller to Wind Turbine System

Abstract

Proven Engineering Products Ltd. is a mechanical engineering company with facilities formachining, welding and plastics formation specialising in renewable energy sources. Theobjective of the project was to improve the human interface and control features of the wellestablished wind turbine system for off grid power supplies with micro-controllertechnology. The introduction of microcontroller technology will enable a gain in market shareand the knowledge transferred into the company to allow further development and newproducts. 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 gridpower.

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 andadaptable, and to provide customisable features for the growing market. Our present systemis not customisable and requires costly factory set up procedures of many potentiometersand other discrete components. The user has a tendency to modify the settings in the fieldwhich most often require the unit to be returned for “calibration”. With the micro-controllercontrolled system set up procedures for the user to operate can be included and Provenexpect to gain market share by supporting extra features. There is also an emerging marketfrom 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 electronicsmore advanced than discrete components. This represents a major leap in technology forProven Engineering Ltd. who are a mainly mechanical engineering company.

There are two main types of wind power systems. The first is a simple system whichsupplies a simple load for water heating for example. In the second more complex system thewind turbine charges a bank of batteries whose dc voltage can then be converted into domestic230V ac power. Presently the present system requires two systems, however, with themicrocontroller system both types can be incorporated on the same board and even integratedto work together where appropriate.A user interface via a keyboard and LCD status display is included in the new microcontrollersystem. The existing system provides only very crude load control with difficult to use andadjust analogue monitoring circuits. There is no friendly user interface either for the input ofinformation or for display.

The cost of the experiment was ECU 47k and was scheduled to last for 14 months. Theduration of the actual project was 18 months, Several issues contributed to this delay whichincluding the illness of the main engineer on the project and some technical issues with theproject.The payback period is estimated to be within two years assuming the sales increase as shownin section 4 and the ROI is estimated to be 400% within a five year period. However, the


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microelectronics unit only represents 5% of the selling price of the completed wind turbinesystem and the relationship between this project and increased sales is complex. Since it is apart of a system in a developing new market - the project will both increase sales due tobetter functionality and user benefits and making it easier to produce in the increasingproduction needs.As can be seen from the figures below in 17, we expect to double our sales next year andincrease thereafter - based on actual orders and enquires - so increasing both turnover andprofitability.

There were many lessons learned during the project, with perhaps overcoming the fear of newtechnology with help and support being the greatest; and the choice of micro-controller thatbest suited the expertise of Proven and the application. There are perhaps lessons to belearned for the microcontroller industry as well - more work needs to be done to enable smallnon-electronics companies like Proven to easily assimilate and use microcontroller technologyin their products.Another major lesson was the need for detailed planning at the start of the project andaccurate 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 willalso 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 increasein sales this will for the first time allow sub contract board manufacture in economic batchesso cutting costs and improving quality.


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1. Company Name and Address

Proven Engineering Products Ltd.Moorfield Industrial EstateKilmarnockAyrshireKA2 0BAUK

Telephone: +44 (0) 1563 543 020Fax: +44 (0) 1563 539 119E-mail: [email protected]

2. Company Size

The company comprises 12 full time employees and 5 part time. There are three peoplewithin the company who have some electronics expertise, this is focused upon simple powerelectronics with some analogue design.The people involved in the project were Gordon Proven who has a mechanical engineeringbackground but some expertise in discrete analogue electronics.Richard Curtis and Richard Caldow both of whom had a small amount of expertise in digitalelectronics using 74C and CD4000 series CMOS.

3. Company business description

Proven Engineering Ltd is a small independent multi-discipline company with facilities inhouse for machining, welding, plastics forming, permanent magnet generator construction andbasic electronics. Proven’s main business is in mechanical engineering, manufacturing metalproducts but we have developed expertise in process control and automation and havedeveloped our own wind turbines using our novel design of turbine blades. Provenmanufactures and installs the wind turbine systems which include all the metal work, windturbine blades, battery and inverter and controller. Only the batteries and inverter are boughtin from a third party. These systems are mini power stations for use in remote locations suchas houses, farms, remote phone systems, remote water pumps, etc. They require their ownpower 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 sizerange; and a growing World reputation for wind turbines which are tough and reliable. Wehave only a few competent world competitors - Bergey of the USA being the mostsignificant. More competitors are emerging and the market is simultaneously expandingrapidly. To stay competitive we have to provide better functionality - especially in Hybridsystems (e.g. Wind Solar Hydro combinations) and lower costs. Without the FUSE projectthe 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


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would less quickly.

Proven Wind Turbine and Renewable Energy Sales

Year 92 93 94 95 96 97 98 99

Number 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 monthsValue for 99 based on order book and known sales in pipeline. Gordon Proven

Year

92 93 94 95 9697 98

99

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 controlsystems since 1980, and developing small wind turbines (600W to 6000W) since 1981. TheWind turbines have been on the market since 1992 and there are now over 150 systemsinstalled world-wide. These are mainly in the UK but with several installed in the FalklandIslands (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 existingcustomers.The main market to date has been from domestic users but there is a growing demand from theindustrial 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 toincrease the service areas. It is frequently impractical to bring mains power to these sites andas 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 theterrain prohibits the use of cables. The domestic market tends to be cost sensitive and theindustrial sector is looking for reliability and how the system will function within theirexisting equipment. The industrial sector often requires the inclusion of certain specifications


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and system operation which may be slightly different than normal. The present equipment istherefore ruled out of this latter market since it is of fixed operation and not easilycustomisable. It is believed that market share can be gained by the inclusion of more featuressince customer feedback suggests that it is the features that can tip the balance from a non saleto a sale.

This year two of the major UK mobile phone companies have opted for Bergey (USA) windturbines - in preference to Proven – due, we think, to us not being quite ready with ourtechnology for that market. We are expecting to install a test system with one of the othercompanies (One to One) in the next few weeks. The introduction of the microcontroller basedsystem 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 ofthe existing controller with the sixteen adjustable potentiometers.

Figure 1 shows a block diagram of theexisting system. The three phaseoutput of the wind turbine1 isrectified to give a dc voltage which isthen used to charge a battery bank.The analogue circuitry monitors thebattery bank and, as this becomesfully charged, switches in a load todivert power from the wind turbine,therefore controlling the amount ofcharge into the battery bank.In periods of time when there hasbeen little wind or when the demand

for power has been high then the batteries will become discharged. In this case a backuppower source is usually available. This is often an engine driven generator. In many cases thegenerator will be automatically started before damage to the batteries through overdischargeoccurs.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 aninverter.

1 The output voltage of the Windturbine is low voltage three phase. The magnitude depends on the systembattery configuration voltage which is normally 12, 24 or 48 V for battery systems and 120 V or 240 V heating


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BatteryStore

DC DivertLoads

WindTurbine

3ph LV out

AnalogueControlCircuit

AC DivertLoads

Rectifier

Inverter

RelaysContactors

BackupGenerator

ChargeControl

Contactors230Vac

Out

Figure 1 Block diagram of existing system

The wind turbine system can be used for any low power application where mains electricityis not available such as remote houses, farms, telecommunication sites and third worldapplications. Many customers with an existing electricity supply and a good wind resourceinstall a system to offset the amount of conventional power used. This has bothenvironmental and economic arguments.The electronics within the present system are realised by analogue designs using discretecomponents and adjusted by means of 16 potentiometers which have to be set separately foreach board produced. This setting is time consuming and requires the use of a bench powersupply which can be accurately set to the required switching levels. This makes it difficult toaccurately adjust the switching levels in the field and virtually impossible for customeradjustment. However end users have wanted to adjust the levels and attempts have resulted inthe need to return the control board for factory resetting.System information is shown to the user via a series of board mounted LEDs and twoanalogue moving coil meters. These LEDs indicate the state of the contactor and relayswitching 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 inputkeypad 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


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including power etc. to be displayed accurately and replace the two moving coil meters thusreducing the production cost.

6. Description of the technical product improvements

LCD Display

Power Supply

KeyPad

Real TimeClock

Oscillator

AnalogueProcessing

OutputDrivers

PIC 16C74AnalogueSignals(BatteryVoltage,Current)

SerialInterface

PWM signal forproportional 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 themicrocontroller WTcontroller with keyboardand LCD display in finalprototype 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


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modules to be customised and improved with out modification to the main programme orstructure.

Clock, etc.

MainProgram

EEPROM

I2C

Keyboard

SignalProcessing

Voltage

Power

LCDDisplay

Current

PWMOutput

DigitalOutputs

GeneratorLogic

External link

Figure 3 Program StructureThe targeted aims for the new product were met and have resulted in a significantimprovement in the control electronics of the wind turbine.The equipment is now much more user friendly by the inclusion of the keypad and the LCDdisplay. 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 onthe display. This adjustment will allow the user to safely fine tune their system to give thebest performance; but by limiting the access for adjustment by the microcontroller potentiallydamaging adjustment is not allowed.The main effect for Proven, however, by the use of the keypad is the reduced test and setuptime 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 tobe gradually increased or decreased, this has been achieved by the use of a single element withPWM 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 controlelectronics now fit on one board reducing the inventory costs and increasing the system’sreliability.

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 switchedoutput to provid a warning of low battery condition.


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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 ofthe technology compared to the predicted sales volumes and the application of the technologyto future product development within the company. Although the unit is not particularlyprice sensitive it must always be borne in mind that the typical customer of this equipment isbuying to a budget and hence price considerations are important. The customer must alwayssee 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 theavailable technologies, such as discrete devices, FPGAs, ASICs and micro-controllers.

Discrete The product could continue to be developed using discrete devices, but there is avery limited scope for improvement. This methodology would greatly increase thecomponent 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 thediscrete system is the difficulty in adjusting the potentiometers which set the switching andhysteresis levels. Expanded displays can not be achieved using discrete componentsconsidered essential for the improved device. New features could also not be handled withouta complete redesign of the system.

PLCs which are easy to program were also considered but were deemed to be too expensivefor 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, costingalmost 1,000 ECU’s. This design was too costly for the domestic user Although extremelyversatile in industrial control applications attempts to use PLCs in the past for wind turbinecontrol applications have not be favourable. Several external components such as a displaymodule 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 thedevices also need to be considered. We need a system with minimal power consumptionespecially in the smaller systems as every watt used by the controller needs to be producedby 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 tocomplement the FPGA’s 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 bedeveloped which not best suited to FPGAs. There would be a steep learning curve associatedwith the implementation of this technology in this application resulting in an excessively longtime to market.

ASIC products were examined, but ruled out due to both the high tooling costs and high unitcosts for the volumes considered. Risks are also unacceptably high presenting a very steeplearning curve for this technology.


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Micro-controllers Although micro-controllers are relatively slow devices in comparison withFPGAs, they function best in a serial application environment, such as the Wind TurbineSystem. 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 widerange of serial peripherals e.g. memory, real time clocks etc.. Moreover, the unit costs are lowand the perceived implementation speed is higher than with other technologies. The PaisleyUniversity feasibility study also concurred that the micro-controller would be the mostsuitable technology for this application.

Several micro controller families were initially considered and development began using theThompson ST6 family. This family met all the hardware needs required for the plannedproduct. These included analogue inputs, on chip EEPROM for user parameter storage and aPWM feature. Another major benefit seen was the availability of a high level graphicalprogramming aid called Realiser. This allowed the required design to be entered in a schematicform and then a complete programming code file is generated ready for downloading to aspecified Thompson micro controller.Proven were concerned that knowledge transfer should take place but being a small companyit was only possible to dedicate one employee to the main programming aspects of theproject. As the knowledge gained would be lost if that employee left the company, thedeciding factor to choose the Thompson ST6 was that it could be programmed easily by theuse of the Realiser software package, and so any of the engineers in the company could easilyacquire the knowledge needed to use and maintain the system.. It was also felt that codechanges after a length of time would be easier if they were made to a schematic rather thanfollowing 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 systemfrom a library of logic functions, timers, counters, etc., and indicates which pins of the microcontroller are connected to the various inputs and outputs of the schematic. The softwareallows the circuit to be simulated and tested with a range of virtual instruments and at thepress of a button produces the required programming file. Using this software package meantthat in a very short time a first micro controller board was built which replicated all thefunctions of the existing controller.One of these early ST6 based boards was incorporated into a wind turbine system andinstalled 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 requiredfunctions in a schematic format, for example initialisation of the LCD display but only oncewhen the program began.

At this time in the project Paisley University (the TTN) was attended for a course in LCDdisplays. This was the first formal training undertaken. On the course the Microchip PICfamily was introduced. The instruction set for these microcontrollers was fairly simple tolearn and it was discovered that there was a wealth of information from the manufacturers andalso many third party sources.Following the course it was decided to focus the design on the PIC microcontroller family.


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As the micro-controllers form a significant part of the control PCB, which was designed andmade in-house using the layout package EasyPC, initial testing was carried out after the PCBhad been populated and assembled. This included basic functionality testing by means of asmall test rig at an electrostatic-free workstation.Final testing was carried out on the fully assembled unit operating in a diagnostic testsequence

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 thedesign 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 degreesand one with an Electrical HNC. All have experience in the Renewable Energy Field and arefamiliar with the requirements for the Control system.Although discrete analogue electronic controls had been developed and used over several yearsthere was no-one in Proven with the appropriate knowledge or experience to enable a moveinto Microcontroller technology with the complex real time feedback control systems neededfor effective system control and stability.Several attempts to assimilate and master micro processor technology had been made in thepast but without result.

9. Workplan and rationale

The work plan and effort in person days together with estimated costs is shown below. Thefirst table below indicates the effort and costs, both planned and actual and the other theschedule that was planned in the original Technical Annex before the start of the ApplicationExperiment. Due to illness and some design changes the project needed to be extended by fourmonths, this is reflected in the extra time spent on the management and design of the windturbine system.

Estimated Actual

ActivityEffort in persondays Costs

kECUs

Effort inperson days

CostskECUs

Management 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


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The original workplan is shown below.

Activities Month1 2 3 4 5 6 7 8 9 10 11 12 13 14

ManagementProject Management X X X X X X X X X X X X X XSpecificationFunctional Spec. X XSystem Spec. X XTechnical Spec. XTrainingMicro-controller Training X XDesignSystem Level X XSub system Level X X X XEvaluationPrototype Production X X X X X X X X XTest set up X X X XFunctional Test X X X XPrototype Test X X X XField 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 algorithmsdiscovered during the field test stage of the project. This added two months to the projectbetween 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 theregular management of the project but also time allocated to the monthly monitoring meetingsand the preparation of the monthly reports. An extra 6 days were spent on the managementof 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 projectand a specification was completed in this time frame. The initial plan was to use the ST6micro-controller from Thompson, the main reason being the associated Realiser softwarepackage that allowed the design to be entered in a schematic form to produce the correctcoding. This micro-controller was chosen since it was felt that this would provide a simplelearning 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 resultof the training undertaken at the University of Paisley a major change was made to thespecification. It was decided to use PIC micro-controllers for all of the design. This isexplained more fully in the design section. As a result of this change extra time was expendedon 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


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operation PIC micro-controllers. The training, tailored to Proven’s needs, focused upon theprogramming 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 andthe serial bus operation of the PIC Micro-controllers.Informal training was undertaken separately by extensive use of published literature and dataCD Roms. Arizona Microchip, the manufacturers of PIC micro-controllers also have acomprehensive 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 beingthe 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 muchbetter product.Also during the actual field tests ( as opposed to simulated testing ) it was found that some ofthe control algorithms were not able to cope with the constantly varying input from the windgenerator. These had to be refined and added to the time. Time was also spent upon theanalysis of an inverter module. This activity although extending the time spent on the designphase of the project, has enabled us to gain valuable knowledge of inverter technology andoperation allowing the accurate specification and purchase a commercial inverter that meetsthe 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 previouslyenvisaged giving much greater control of the loads. This was not in the original specificationbut was included as our knowledge increased regarding the features and operation ofmicrocontrollers.The printed circuit boards were manufactured in-house using single sided copper board toreduce 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 ina modular fashion. As each module was designed and the software developed the hardwareand 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 inreal 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.


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Throughout the duration of the project, development has continued using two prototypeboards. One of these has been used with the emulator for bench testing. The other has beeninstalled within a wind turbine system at the Proven Engineering factory. This has allowedongoing testing with a real system as soon as a new section of code or circuit has beencompleted. The testing of the code has been completed with the watchdog feature of themicro-controller inhibited enabling all faults and software problems to be monitored bydisallowing 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 hadto be fine tuned to cope with the constantly variation of the wind. These tests could not bedone on the bench and are necessary since the welfare of people and the successful operationof remote repeater stations need to operate with minimum maintenance because of theirremoteness.Evaluation time of the product approximated the time planned in the original proposal.

10. Subcontractor information

University of Paisley,High Street,Paisley,PA1 2BE,ScotlandPhone (44) 141 848 3419The University of Paisley was chosen as the training subcontractor because of its closeness toProven’s premises (only 30 Km from Proven’s premises) and for its ability to tailor coursesto the specific company’s needs. The costs were also competitive. All thses matters regardingthe content of the courses and the costs were discussed and a contract written and signedcovering all the relevant points before the training commenced.

The training focused upon the programming and features of PIC micro-controllers since thiswas 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 andthe serial bus operation of the PIC Micro-controllers.

Design assistance was also provided by the University of Paisley.

EMC Compliance Services15 Hal RoadNemphlarLanarkshireML11 9JE

This subcontractor was used for design assistance and advised Proven on our design withreference to compliance to EMC regulations.The circuit and its operation were reviewed by EMC Compliance Services for problems who


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advised on minor changes in PCB layout etc. No formal testing for EMC compliance wasperformed since this will be done on the completed unit. No charge was made for this EMCdesign advice.

11. Barriers perceived by the company in the first use of the micro-controllertechnology

The main barrier perceived by Proven was the knowledge barrier. The electronics experiencein-house was only concerned with simple discrete circuits. There was no knowledge of digitalelectronics and hence how to develop a development schedule for a micro-controller.However, Proven knew that the knowledge of digital electronics would enable them toproduce products to serve many different applications related to renewable energy and so feltthat 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 feltthat we should use the simplest method of data entry and this seemed to be provided by theST Realiser system. This micro-controller also had a number of built in features not availablewith other products, although able to be added using external components utilising the serialbus.

Since Proven sells the wind turbines in very low volumes it is difficult to use contractors forthe electronic assembly. A subcontractor minimum assembly run could provide theelectronics for well over a year’s production causing cash flow problems. The result is thatsubcontractors for assembly can not be used and Proven must acquire these skills of assemblyand 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 upto date. If this did not happen then Proven would be more reliant upon their metal workskills, this would hamper growth of the company and make our products less competitive in arapidly 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 marketshare to grow and to be able to provide features to ensure its long term sales. Several yearsago we approached the Department of Applied Physics at the University of Strathclyde whoconducted a feasibility study concluding that the microprocessor technology could be used inan improved wind turbine. Several years later we heard about the FUSE programme throughadvertising by the TTN and we contacted Paisley who did another feasibility study. Becauseof 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 othertechnology options were considered.

The structured approach taken in developing the Fuse proposal which included the detailedproject plan gave us further confidence that we could complete the project and its detailedapproach 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


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project should be completed using microcontroller technology.

A training was also developed which not only included formal training and design assistancebut also included the use of the Web for information and access to other independent expertswho could go into more detailed training on the specification and design of high currentequipment.The financial support that the Fuse programme provided was very important and thisremoved the financial barrier although we now see that we will be able to recover the cost ofthe development relatively easily with the increased volume and selling price of the windturbine with the extra features.

Throughout the project we also found networking with other First Users useful in giving usinsights into others experiences etc.

13. Knowledge and experience acquired

The main area of experience gained is in managing a complex project involving microcontrollertechnology at the core.The training courses were of great help in acquiring the technical skills quickly. We now havethe capability to specify and design micro-controller projects using the knowledge we havegained from this FUSE project. This has already been shown by our first replication projectusing a micro-controller. This is an automatic start for a diesel generator which is incorporatedinto a micro hydro power installation.

The involvement with the electronic peripherals including LCD displays, keyboards, memoryand serial busses has generally updated electronic skills. Whilst sourcing these parts fromtechnical catalogues and journals other equipment and information was discovered which hasbeen useful in other areas. The above training and experience equips us to define and developmicroelectronic projects for the future growth of the company.

Our design skills have been enhanced through our attempt to design the inverter and a betterworking knowledge of power electronics has been gained including the use of IGBT’s.Although the final use of power electronics in the project has been limited to the PWMswitched load, the early experiments and investigations into IGBT’s has led to these devicesbeing used as a replacement for MOSFET’s in the Proven Wind Turbine heating controller.The IGBT’s are considerably less expensive than the previous devices used and have provedover 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 ownPCBs. This package, EasyPC by Number One Systems Ltd., is only a simple design packagebut 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 localPCB supplier. The manufacturing contract is being developed and training and experience theFUSE project has given us in dealing with subcontractors gives us confidence to use suchsubcontractors.


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Most gratifying to Proven was the fact that we have been able to complete this project usingtotally new technology to us with the training and design assistance suggested in the originalplan.

14. Lessons learned

Many lessons were learned throughout the execution of this project. A surprising numberfrom going down paths that did not go anywhere but introduced us to other aspects ofelectronics that was beneficial to the overall project and to our present products providinggreater reliability e.g. the use of IBGTs.

The instruction set for these micro-controllers (PIC) was fairly simple to learn and it wasdiscovered that there was a wealth of information from the manufacturers and also many thirdparty sources.Microchip provide a CD-ROM with comprehensive device information and large library ofapplications 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 useassembly language programming of microcontrollers. Micro-controller technology, with thecorrect guidance, can be adopted by companies who have little electronic engineeringknowledge; but a great deal of time and expertise had to be acquired before we could achievethe complex control systems we needed.

The time required for software development should not be underestimated, sources of goodexamples of coding can be found by using the Internet. The knowledge on how to use a microcan be fairly quickly obtained but coding can take a lot of time.There are discussion groups where solutions to frequently encountered problems can befound. 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 controller’s features, but ofcourse until the capabilities are well known this is not always possible, this is where earlydesign assistance and training is most useful. Care and consideration is necessary in theselection of the function of each I/O pin to optimise the function and minimise codingchanges.

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 itbecame 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 theinternal timers could be set to measure periods of several seconds. This crystal required thesacrifice of two particular I/O pins. These pins were being used for other purposes andtherefore the code had to changed. At this point in time all the I/O allocation was reviewedand changes were made in several sections. These changes were possible as the final hardwarelayout was not fixed. If we had been at the stage where a hardware layout had been finalisedthen we may not have been able to use the timer controlled by a second crystal. A softwarefix 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


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planning. On the more complex micro controllers there are so many inbuilt features andfunctions that it is difficult for a first user to incorporate them into the initial design. As timepasses something may be discovered in an application note which has a beneficial effect onother parts of the project. With the knowledge gained this situation should not occur in anyfuture new products.Towards the end of the project the engineer associated with the software of the project leftthe company. This was a big blow since we had invested a large amount of training in him. Wecan not stop anyone leaving the company to go to another job but we could have written intohis contract that a proportion of training costs should be repaid if should he leave within acertain time of completion of courses. This repaid money could then be used to enabletraining 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 ST6microcontroller was not adequate for the total project’s needs. By taking advice and attendingtraining courses the fact that the project could be completed using the PIC family ofmicrocontrollers was established. A great benefit which speeded up the design anddevelopment process was the purchase of a PIC emulator. Without it written code had to beloaded into the PIC16C74 available in EPROM style so each modification required UVerasing. This process is slow and although emulators are relatively expensive the time saved innot having to erase EPROMs and being able to debug code while it is running in real timewhile running the hardware makes them invaluable. Programme changes can be made inseconds 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 anintegrated inverter module controlled by the system microcontroller.From the reading of text books on the subject of power electronics this looked perfectlyfeasible. However as time passed it was discovered that this area of electronics was not quiteso easy to put into practice. Further reading of manufacturers data sheets and technicaljournals led us to the conclusion that physical layout of the circuits is critical for reliableoperation. This physical layout appears to be of such importance that some suppliers ofpower electronic devices will freely issue a printed circuit board design to incorporate into theusers own design. Careful consideration needs to be given to track layout, interconnectingwires and placement of the switching devices on heatsinks.The above problems and the need for very expensive test and safety equipment necessary forthe 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 specialisttraining and equipment.The knowledge and experience gained while investigating inverter design has not been wastedsince it has allowed us to define our requirements accurately and has allowed us to find a localcompany who currently manufacture a suitable product. They are willing to work withProven 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


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produced by a local PCB manufacturer. The boards will have extra ground planes for reducednoise and more layers to assist in the PCB assembly.The microcontroller based board, built in batches of 50 – 100 by the subcontractor, actuallycontains more components and will be slightly more expensive in component cost than theexisting board in the Wind Turbine Controller. However, the use of a specialisedsubcontractor will result in a cost reduction of about ECU25 per board (out of ECU90) and agood increase in quality as well as functionality compared to the present board which is madeand assembled in house. Reliability will be greatly enhanced by the removal of thepotentiometers and having the controls set digitally by the microcontroller programme.

The final product will be fitted into the existing switchgear cabinet. The industrialisation costis confined to the cabinet modifications only since the microcontroller replaces existingelectronics. The total cost of these modifications will be less than ECU500. There will alsobe an added cost of reprinting brochures to include the extra features of the system. The costof this, for the first run, is estimated to be 600 ECU. This work will be complete early in1999 and the first Wind Turbine with the new microcontroller board is expected to beshipped 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 entirelocal power management gives us a better capability than almost all of our competitors. Thiscan open up new applications such as: control of Diesel Generators and with the use ofancillary inputs can operate Solar PV etc.. The system also gives historic information usefulto the user and to Proven. Since the complete control of the system makes life much easier forthe 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 forindividual users but since this will only involve the software no changes to the hardware willbe necessary. It is also planned to investigate further features that would be desirable to haveto enable the development of a range of related products that could be offered at an enhancedprice structure.

The knowledge gained of using microprocessors will not only be of use to this project. Manyother applications have already been identified.The controller has been designed with some element of flexibility to allow for a degree ofcustomisation 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 wheredamage will occur. This feature was specified for an Ecology monitoring project where theexhaust fumes from the generator engine would affect data readings.

• A system that provided power in a youth hostel needed to shut down low priority loadsas the batteries became low. Visitors to the hostel do not always realise that the amount ofelectric power was limited when there was no output from the wind turbine. If too manylights were left on and the stored power became low then the lights would be madeunavailable. Power was still available to the warden and for the fire alarm system.


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The above features could all be incorporated by using spare inputs with some softwarechanges. Previously they would have to be added in using separate control boards based onanalogue and digital discrete circuits.It is not planned to customise every system but, by including some general purposeinput/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 oncontrol to an existing hydro turbine installation. The control utilises routines written for thefuse 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 thewind to provide power. The controllers of the two systems are very similar and this range ofequipment will use the hardware and several software routines developed for the windturbine.

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 agreatly enhanced competitive position.As can be seen from the table below sales have been steadily increasing. The average cost ofthe whole system is approximately ECU12000 with the microcontroller electronicsconsuming approximately ECU200. Without the use of microcontroller microelectronicsProven would not be able to compete effectively with their competitors, this would result indeclining 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 2001Units 14 22 30 44 95 135 180Sales 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 FUSEproject is so small when compared to the selling cost of the overall system. There is a generalincrease in renewable energy sales and the increased functionality of the micro-controllersystem 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 shownabove and the ROI is estimated to be 400% within a five year period. However, themicroelectronics unit only represents only 2% of the selling price of the completed windturbine system and the relationship between this project and increased sales is complex. Sinceit is a part of a system in a developing new market - the project will both increase sales due tobetter functionality and user benefits and making it easier to produce in the increasingproduction needs.Due to its adaptability the micro-controller system can also be used for our newly developedmicro-hydro turbines. The rapid boom in mobile phone users and the requirement for greatercoverage in more rural areas will also increase sales.


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17. Target audience for dissemination throughout EuropeProven Engineering is a small company which has extensive knowledge of their specialisedtechnology and in building machines concerned with this technology. Although Proven hadused electronics in the past their electronics expertise was limited and restricted to discreteelectronics and very simply PCBs.The four digit Prodcom for Proven is 3110, Electric Motors, Generators and Transformersand this demonstrator document would be of interest to companies within this code who planto use microelectronics to control their systems. However, the target audience for this type ofproject covers much more than those companies in this code.This demonstration document therefore should be aimed at a target audience of companies inall industrial sectors producing instrumentation equipment and in particular as described inProdcom 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 andwho utilise poor methodology in defining and executing projects, often resulting in overruns inboth 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 thetechnology to their advantage to stay competitive and in business. The target audience for thisproject is therefore very large.

The project has particular relevance to companies involved in renewable energy projects suchas the generation of electricity by means of wind or water power. Proven Engineering aremembers of the British Wind Energy Authority and members of the Small Wind EnergyCommittee within this organisation and plan to discuss the project with them to show thebenefits of electronics. Targeting similar bodies throughout Europe would further expand thetarget audience.


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17.1 Post Script

Unfortunately Richard Curtis - the main staff participant in the programming part of projecthas decided to go back to England and leave Proven. Although this will no doubt disseminatethe 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 aneasily useable microcontroller system which could be used on a casual basis by any non-expert engineer ( much as PLC systems have become).


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