electrical grid requirements dowec · electrical grid requirements dowec dowec nr: 10042 rev. 3 ......

Electrical grid requirements Dowec

DOWEC Nr: 10042Rev. 3

Name: Signature: Date:Written by: JBZ 15-04-04Checked by FG, JAK,CSPSigned by: OSO

Version date No ofpages

0 all New / review document1 13/05/02 div Update to Dutch grid-codes from version April2 10/10/02 all Update to UK recommendation G75/13 22/10/03 all Public version

TITLE DOCUMENT: ELECTRICAL GRID REQUIREMENTS DOWEC VERSION: 3DOCUMENT NO.: 10042 PAGE: 2/22

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1 . CONTENTS

1. CONTENTS..............................................................................................................................................2

2. SCOPE.......................................................................................................................................................3

3. DEFINITIONS..........................................................................................................................................4

4. GENERAL NORMATIVE REFERENCE LIST ..................................................................................54.1. TURBINE SPECIFIC NORMATIVE REFERENCE LIST ..........................................................................................5

5. PARK SIZE RELATED REQUIREMENTS.........................................................................................6

6. REQUIREMENTS FOR THE WIND FARM AT THE ONSHORE CONNECTION POINT ........76.1. POWER PLANNING AND CONTROL REQUIREMENTS......................................................................................76.2. REACTIVE POWER REQUIREMENTS................................................................................................................96.3. VOLTAGE / CURRENT RELATED REQUIREMENTS......................................................................................106.4. FREQUENCY/VOLTAGE REQUIREMENTS ............................................................................................................126.5. MEASUREMENT BY DTE OR UTILITY (TIME SYNCHRONISED)...........................................................................146.6. PARK MEASUREMENT & REGISTRATION ..........................................................................................................14

7. RELIABILITY .......................................................................................................................................157.1. RELIABILITY SHORE CONNECTION...................................................................................................................157.2. RELIABILITY WIND FARM COLLECTION PLATFORMS.........................................................................................157.3. RELAIBILITY WIND FARM GRID INFRASTRUCTURE ............................................................................................15

8. APPENDICES ........................................................................................................................................168.1. APPENDIX 1: VOLTAGE FREQUENCY PICTURE ...............................................................................................178.2. APPENDIX 2: FAILURE EFFECT ANALYSE.......................................................................................................198.3. APPENDIX 3: HV GRID IN THE NETERLANDS.....................................................................................................218.4. APPENDIX 4: MEETINGS AND DOCUMENTATION LIST....................................................................................228.5. APPENDIX 5: RESPONSIBLE ENGINEERS ...........................................................................................................22


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2 . SCOPE

This document gives an overview of the technical requirements for the electrical connection of largeoffshore wind farms. The focus in this overview is on wind farms 20-100 km from the shore and parksizes of 100 MW and more. This document is not intended as a replacement of the national regulations,but as a summary of all requirements in The Netherlands, Denmark, Germany and UK. Information onthe requirements in other countries may be added later. Local deviations can be expected, since nationalregulations for large offshore plants are still in development. Furthermore, local grid operators arealways entitled to specify additional requirements. Experience from the first large offshore farms mayalso lead to additional requirements or changes.

Wind farms are not an ideal power source since the wind is stochastic in nature. This variability will haveconsequences for the ability to fulfil the current grid requirements, written for large power plantsequipped with synchronous generators. Wind farms can not meet all requirements, but on some aspectswind power plants may perform much better than conventional power plants (for instance fast powercontrol).

If several documents on the same requirement are available, the worst-case scenario was taken in thischecklist. If behind an item both NL and DK are mentioned, then both countries have this requirement. Aspreadsheet was prepared which includes the regulations for NL, DK, D, UK.

Requirements are sorted on the basis of voltage, power, current etc. as opposed to sorting by normal versusexceptional conditions. Normal Operation Requirements are highlighted light grey.

This overview is prepared as part of the Dowec project. In the Dowec project a wind farm case studywill be made of:• a 100 MW farm, 20 km out of the coast;• a 600 MW farm, 60 km out of the coast;

Which corresponds to two major Dutch projects (see Dowec Terms of Reference).

The document is considered to be a living document and new information will be added when appropriate.


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3 . DEFINITIONS

Onshore grid Existing or extended power transmission network on shoreOnshore grid connectionpoint

The mutual point between wind farm cabling and the onshore grid

Wind farm collectionplatform

Platform & housing where electric power of several turbines is collected andtransformed to a higher voltage level

Offshore wind farm The wind turbines, offshore electrical network and the connection to shoreMax /rated /min power 10min average max/rated/min power at the onshore grid connection pointMeasurement point/Accounting point

Location of the kWh measurement. This is expected to be located at theonshore grid connection point

Communication point The location of information exchange between the grid operator to the windfarm. This is expected to be located at the onshore grid connection point

Park power setpoint Park power demand prescribed by the grid operator, realisation is limited bythe wind conditions

MV AC voltage levels 11..69kVHV AC voltage levels 110.. 380 kV (UK supergrid > 200kV)HVDC-light DC power transport system, made by Siemens and ABB, based on IGBT

convertersConverter A thyristor or IGBT bridge to convert AC to DC or vice versaGrid levels Voltage / current / frequency etc. at the onshore grid connection pointWind farm status Information exchange to the grid operator of the operating conditions of the

offshore wind farmIsc Short circuit currentResponsible expert Technician responsible for safe operation

(nl: verantwoordelijk deskundige)Program responsibility Planner responsible for power production

(nl: programma verantwoordelijke) ( UK TSO)PV curve Power / wind speed curve of a turbine

Grey marked blocks Grey marked blocks are to be considered normal operation


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4 . GENERAL NORMATIVE REFERENCE LIST

STANDARD DESCRIPTION (1) (2) (3) (4)

ISO 9000 series Quality systems. Models for quality assurance indesign/development, production, installation and servicing

NL DK UK SP

NVN 11400-0 Criteria for type-certification of wind turbines NL DK UK SPApplicable directives of the EEC For instance machinery directive (89/392/EEC), EMC directive

(89/336/EEC) and low voltage directive (73/23/EEC).NL DK UK SP

NEN 1010 equal to IEC 364 Safety requirements for low-voltage installations NLIEC 76 Power generators standard NL DK(N)EN 50110-1&2 (High) voltage operating safety rules (NEN 3140 / 3840) NL(N)EN 1041 Operating rules for high voltage installations NL(N)EN 3840 Operating rules for high voltage installations (design) NLNPR 7640 Operating rules for high voltage installations (design) NLIEC 726 Dry power transformers standard NL

Netcode 99-12-15 Regulations for grid connections 110kV or higher NL

System code 99-12-15 Dutch grid document NL

Recommendation G75/1(added 10/10/02)

UK recommendations for powerplants > 20kV or > 5MW UK

IEC60909-1 Fault current contribution UK

EN 50160 NL DK

TC88 / IEC 61400 Power quality standard NL DK

Electricity Act 1998 Dutch law on electricity transport and production NL

IEC 1000(3-7) (868) Harmonics standard NL DK

IEC 61000-3-6IEC 60533-11

Emission limits in MV & HV power systemsEMC fixed offshore units

NLNL

IEC 61000-3-7 Emission limits in MV & HV power systems (fluctuatingloads)

NL

IEC 60044-1-3 // IEC 60168IEC 60688

Measure converters & transformers standard NL

DNV Certification agency Det Norske Veritas ??

GL Certification agency Germanischer Lloyd

IEC 60870-6 Inter control room communication protocol DK

List is not limited t above

4.1. TURBINE SPECIFIC NORMATIVE REFERENCE LIST

STANDARD DESCRIPTION (1) (2) (3) (4)

IEC 61400xx Wind turbine generator systems NL DK

NEN 3173 Safe operation NL

EN 50308 Personal safety

IEC 60034-1 Rotating electrical machines


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5 . PARK SIZE RELATED REQUIREMENTS

The applicability of requirements may depend on the park size. For wind farms larger than 8MW, theDutch Grid Operator does not have the legal obligation to connect the farm to the grid. For wind farmslarger than 8MW, a grid extension needed for the connection, may be charged to the wind farm owner.

The loss of the total wind power due to a fault in the connection to shore may be a criterion imposed bythe grid operator to request the division of the power transport to shore over two or more parallelconnections. Small offshore wind farms can be assumed to be connected by a single cable. For windfarms larger than 150..200 MW a multiple connection may be requested. Local grid properties may playa role in the choice of the type of connection and number of connections to shore.

Requirements related to the park size:

CONDITION REQUIREMENT (1) (2) (3) (4)

Large wind farm NL (> 8 MW), UK (>5MW) NL UK

Acceptable power loss on error NL (150 MW) NL

Voltage level to transport2 MW turbine

1..23 kV for star park configuration1..34 kV for string park configuration

NL

Voltage level to transport3 MW turbine

34 kV for all park configuration NL

Voltage capable to transport5..6 MW turbine

34 kV for all park configurationUK (> 20kV)

NLUK

Park voltage below 100 MW parksize

36-50 kV AC

Park voltage for 100-300 MW parksize

110-150 kV AC in 100 MVA clusters80 kV DC in 50 MVA clusters

Max power in maintenance 60 MVA NL

DC voltage levels depend the supplier: converter / cable form a design pair


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6 . REQUIREMENTS FOR THE WIND FARM AT THE ONSHORE CONNECTION POINT

6.1. POWER PLANNING AND CONTROL REQUIREMENTS


Power Yearly averageWithin ?% accuracy seems reasonable at this moment

NL

Active and reactive power Monthly averageWithin ?% accuracy seems reasonable at this moment

NL

Active and reactive 10 minuteaverage power

Week planning with 70% assuranceWithin ?% accuracy seems reasonable at this moment

NL


Daily planning with 93% assurance (36h)Within 7 ?% accuracy seems reasonable at this moment

NL


4 hour warning system for deviations from the plannedpower production, for instance due to changes in weatherconditions

NL

High wind speed wind park shutdown

Planning 15 min ahead (sequential switch-off over a periodof 15..120 min)

NL DK

Low wind speed cut in Planning 15 min ahead NL DK

High wind speed cut in Planning 15 min ahead (see notes) with dP/dt limitation

NL DK

dP/dt Pnom / 60sec12MW / 60sec10% of nominal power / 60 sec

NLDK .

D

Maintenance Yearly planning on daily basisMax 6h of 60MVA

NL

Repair Grid operator notification of major repairs10min of 100MW for single fault

NL

Rotating reserve / standstill reserve Participation unknown NL

Park power setpoint normal operation: 10 sec value of active power setpointbetween 1% and 105%active power command in 2 sec 105% down to 20%

(overproduction will be limited by the thermal constraints)

NL DK

DK

D

NotesThe Dutch Grid Code does not mention power electronic converters connecting to the high-voltage grid.

However, their impact on the grid connection point will be evaluated by the grid operator.

A report structure to cover operation, maintenance, faults etc. similar to the one for land based HV gridsmust be set up by the “responsible expert” (verantwoordelijk deskundige).

It is unlikely that a wind farm will have a program responsibility, but the long term and short-term powerprediction is necessary. Models to predict the power within a 48 h time frame are required to give theutilities an adequate tool to anticipate production changes. Otherwise, wind power will be considered as"low value" power.


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Soft switch in /out procedures are necessary to give grid control equipment, for example transformer voltagecontrol or power control of large generators, time to adjust to new conditions.

Power regulation speed of 150-200 MW power plants is expected to be around 12 MW/min. Assuming anequal amount of rotating reserve, this means 36 MW/min for a wind farm of 600 MW and a shut downfrom maximum power to zero should take 15 min. This value appears to be acceptable for all involvedparties.


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6.2. REACTIVE POWER REQUIREMENTS


Power factor during normaloperation

Between 1 and 0.8 inductive (nl >50kV) (UK 0.85) 1..and0.85 cap (nl > 50kV) (UK 0.95)The power factor affects the voltage regulation and is subjectto discussion with the utilities (Utility preference +0.9 to –0.9)

Reactive power, also in no-wind periods, is valuable

NLNL

DK UKUK

Reactive power setting Reactive power command every 10 sec NL DK

NOTE

If capacitieve reactive power is needed, the logical place to produce this, would be at the onshore gridconnection point. In case the wind farm is not fully loaded or if the cable has spare capacity, thenreactive power production at the farm is an option.


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6.3. VOLTAGE / CURRENT RELATED REQUIREMENTS


U > 106% Un110% Un > U > 90% Un90% Un > U > 85% Un> 80% Unom<85%85% Un > U > 70% UnU < 80%70% Un > U > 60% Un

Soft switch off after 100msecPower according to PV curve or nominal for unlimited timePower according to PV curve or nominal for 15 minPower according to PV curve or nominal for unlimited timeSoft switch down after 3 secPower according to PV curve or nominal for 10 secSoft switch off after 3-5secAfter a voltage disturbance the power has to return to normal valuewithin 30sec

Power setpoint control still must be active

NLNL

NL

DK

DK

DUK

DD

Voltage dips 0.7 > Unom > 0.6 for 10 sec at 90% of rated power(Utility preference 110% of rated power)0.6 > Unom > 0.0 for 100ms ( Duits = 150 msec) No grid disconnection will occur0.6 > Unom > 0.15 for <3 sec power 1.2* Inom (curve)

(UK G75/1-9.3.3 to ride trough decide depend on connection point )

NL

NL

DK

DK D

D

UKIf the voltage dip has a rest voltage of smaller 0,7 Un,disconnection is allowed after 300ms or 90% of the criticalIsc (KKT) if 300 ms > 0.9 KKT (KKT a value depending on the running inertia)

For grid connections with a voltage of 110kV or higherdisconnection is allowed after 300ms or 90% of the criticalIsc (KKT)

NL

Short circuit fault with disconnection If a production unit is switched off from the grid by a externshort circuit condition. Then the units must be fullyoperational after 30min the event unless the return will takelonger than 60 min

NL

Single phase short circuit fault 0.7 > Unom > 0.4 for 300 msec at Isc conditionsavailability of full power 1.5 sec after fault clearance

NL DK

Voltage regulation

Example of reactive power setpoint versus voltage

If a turbine with reactive power control capability isassumed, voltage regulation at the grid connection point is anoption, similar to the voltage control of a power plant withsynchronous generators.NL = debiet = 10%If the voltage regulation is active, but no reactive powersetpoint is specified by the grid operator, a Q(U)characteristic similar to figure on the left can be expected.

NL

Voltage variation Variation caused by the wind farm at the gridconnectionpoint may not be more than 2% UnomDK (< 3% continuous or <2.5% 10 times per hour or <1.5%100 times per hour)UK ( < 3% continuous and <6% unplanned outages)Inrush currents (due to magnetisation e.g.) may not lead to a higherdeviation

NL

DK

UK

Asymmetry 2% for unlimited time ( nl outside boundary for 168h.y)(optionally controlled by a converter)

NL UK

Flicker Pst < 0.3, Plt < 0.2 NL DK


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Harmonic THFF <1%THD < 8% sum to 40 harmonicEMC compliance has to be proved

NL

NL

DK

Overvoltage protection The offshore cable is extremely difficult to repair. Thereforespecial attention has to be taken to avoid insulation damagedue to overvoltage130% of initial voltage reduced to 120% of nominal voltagein 100msecOvervoltage and switch actions have to be analysed carefully

NL DK

Cut – in current Max 1.2 * nominal grid connection capacity D

Disconnection From the grid to the wind farm, a reliability of 0.9998 isexpected, or average of 1.56 h/yMostly a connection for a wind farm is not shared withothers (no consumers connected to the grid through the samecable). This is also expected for the grid connection point.

NL

NOTE S

More complicated voltage dips are possible. Voltage dips to 60-0% of rated voltage may take 100 msec,followed by a 200 msec period of partly recovered voltage and 100 msec voltage disconnection. Auto-re-closing procedures have to be discussed for these conditions (3 autoreclose sequences may occur / minutewith max of 1 event /24h)

In order to keep the wind farm in operation during a short fault, analysis of the interactions between theturbines may assist in getting the best possible reaction, for instance a number of turbine generators cango into motor operation in order to prevent others from overspeeding.

Ideal reaction on a short circuit can be different from a disconnection event due to loss of magnetisation ofthe stator and subsequent loss of torque or fault strategy.

If necessary, the turbine has to change to speed control in unloaded condition, to keep the rotational speedof the turbine in a safe range and to be able to resynchronise quickly. After 5 minutes a shutdownprocedure can be started.

Fast voltage control can limit the effects of a short circuit condition.


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6.4. FREQUENCY/VOLTAGE REQUIREMENTS


Frequency.

Time and power limited

Continuous operation between 48 and 51Hz (Norm = 50±0.1 Hz)Limited operation range between 45 and 48Hz (>5min)Limited operation range between 51 and 53Hz (>5min)if under/above these limits, disconnection after 0.3 sec isallowedContinuous operation between 47.5 and 51.5HzLimited operation range between <47.5Hz after 200sec)Limited operation range between >51.5Hz after 200sec)if under/above these limits, disconnection after 0.1 sec isallowedContinuous operation between 47.5 and 52HzLimited operation range between <47.5Hz after 20sec)

NL DK

D

UK

Frequency deviation Contribution to the primary frequency control, limited by thecontrol strategy and the wind conditions 1.05% Pnom at 48Hz // 100% Pnom at 50Hz >50.25Hz reduce power

Active power demand by grid operator due to frequencydeviation

NL DK .

D

D

Normal and abnormal conditions

Some countries specify 0.6Un instead of 0.7Un (DK)

NL DK

Comments on the f-U diagram For production units on grid lower than 110kV:disconnection is allowed after 300ms for a voltage dipbetween 0,8 Un en 0,7 Un

NL


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NOTE S

Different frequencies do not cause a problem for wind turbines as long as the control strategy is adapted. Theonly limitation expected may be thermal overload and must be avoided by reducing the load.

Limitations for different voltage levels can be expected: thermal overload and exceeding the pull out-torquemust be avoided by reduction of the aerodynamic power.

Primary frequency control: the drop dP/df can be different for negative and positive frequency deviations.


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6.5. MEASUREMENT BY DTE OR UTILITY (TIME SYNCHRONISED)


Active power per phase First power measurement at grid connection point. Accuracybetter than 0.2%Second power measurement is formed by the collected parkdata5 min average periods time synchronised

NL

Reactive power per phase First reactive power measurement at grid connection point.Accuracy better than 0.2%Second power measurement is formed by the collected parkdata5 min average periods time synchronised

NL

Active power setpoint Active power command / 10 sec time synchronised NL DK

Reactive power setpoint Reactive power command / 10 sec time synchronised NL DK

Measurement accuracy in overload conditions is also specified by DTE (dienst uitvoering en toezichtelectriciteits wet) for Netherlands, secondary measurement will have to register the energy & power in caseof a failure of the primary measurements

6.6. PARK MEASUREMENT & REGISTRATION


Voltage per phase(min/avg/max)

Accuracy better than <0.5%5 min average periods time synchronised

DK

Current per phase(min/avg/max)


DK

Frequency per phase(min/avg/max)


DK

Active power per phase(min/avg/max)

Accuracy better than 1%5 min average periods time synchronised

NL DK

Actual power setpoint Reactive power command / 10 sec time synchronised

Reactive power per phase(min/avg/max)

Accuracy better than 0.4%5 min average periods time synchronised

NL

Actual reactive power setting Reactive power command / 10 sec time synchronised

NOTES

300sec values or event triggered

For failure analysis, a Scada-system (for the park grid protection) is necessary. Failure registration must start10 sec before and end 60 sec after failure event

The communication protocol has to be co-ordinated with the grid operator

In Sweden all power measurements have to be given in 2 s time step to the grid operatorIt is expected that some of these values are open for discussionFarm control & safety strategies may not limit the function to the Netcode demands ( Dutch)


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7 . RELIABILITY

7.1. RELIABILITY SHORE CONNECTION

The shore connection is a very critical point. If a major failure will happen the total power will drop tozero. Dividing the larger parks in to groups and redundant systems may be advisable.


Availability of grid connectionswitch boards

better than 99.78%0.16 failures per year for a system with 4 connectionsrepair time of 5 days

DK

Availability of cable connection(150kVA, 60km )

4 parallel connections of 60km better than 99.7%0.06 failures per year for a system with 4 connectionsrepair time of 21 daysmost probable failure cause are anchors

DK

7.2. RELIABILITY WIND FARM COLLECTION PLATFORMS


Availability of platform switchboards (150kV)

better than 99.78%0.16 with repair time of 5 days over 4 connections

DK

Platform transformer(150kV to 22(32) kV)

better than 99.4%4e-6 with repair time of 60 days over 4 connections

Availability of grid park switchboards(22 (32) kV)

better than 99.99%1.9e-7 with repair time of 30 days over 4 connectionsand at lease 8 outgoing fields

DK

7.3. RELAIBILITY WIND FARM GRID INFRASTRUCTURE


Park cable (60km) design to single fault <100MW for 10min max

better than 99.7%0.06 with repair time of 21 days over 4 * 8 connections

NL

Availability of turbine switchboards (22 (32) kV)

better than 99.99%1.9e-7 with repair time of 30 days over 4 connections

DK

(See grid reliability & cost report for more detail)


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8 . APPENDICES


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8.1. APPENDIX 1: VOLTAGE FREQUENCY PICTURE

In the four shaded areas of the graph, a wind turbine must be capable of delivering power (a, b and c) andcapable of remaining parallel to the grid (c and d).

The following applies in the case of short-circuits in a grid:b For production units which are connected to grids with a nominal voltage of 110 kV or more,

disconnection is permitted in the event of a voltage dip, with the residual voltage having a value of <0.7 Un, after 300 ms or after 90% of the critical short-circuit time if 300 ms > 0.9 critical short-circuit time.

c If a production unit is cut off from the grid because of a short-circuit in the grid, the production unithas to be able to operate in a stable fashion parallel to the grid with all the generators in operationwithin 30 minutes of the short-circuit being rectified. This does not apply if it takes longer than onehour for the grid voltage to return.

If a wind farm is cut off from the grid by an external cause (for example, a short-circuit), the turbines mustbe operational again within 30 minutes.

The critical short-circuit time is defined as:The maximum time, starting from the generator operating at full load, that a short-circuit maycontinue under particular circumstances without the synchronous generator becomingasynchronous after the fault has been shut down.

The critical short-circuit time is therefore only relevant if the wind turbines generate electricity using adirectly connected synchronous generator. After all, a directly connected asynchronous generator isalready asynchronous and cannot therefore become more asynchronous, and a power electronicsconverter as the grid coupling will not lose its synchronous operation in the event of a short-circuit in thegrid. This means that according to 2.1.16 b the wind turbine may disconnect itself after a 300 ms dip.


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German representation of the worst case voltage fault: a 150 ms grid gap (voltage to zero)

NL 2.5.4.7 sate 0.3 sec gridgaps < 0.7


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8.2. APPENDIX 2: FAILURE EFFECT ANALYSE

(ISBN90-5576-096-2 page 200)

Windfarm grid layout concept

UsableGrid models

Safety conceptOperating concepts

Analyse of operatingAnd Failure Statistics

Infeed parametersTopology of windfarmLoad conditionsPossible switch over possibilities

component parametersMTBF / FIT expressionsLoad conditionsMaintenance

Failure effect-AnalyseDetermine area of failureDetermine how to make repairs possibleTime limited overload of rest at failure conditionsSwitch actions after repairs

Critical situations for failure conditions

By analysing By simulationsProbabilistic

What’s still possible if fail

Expectations:Disconnection’s frequencyLoss of productions

Expectations:Loss of productionsRepair & Maintenance

Calculation of reliability and availability figures

Acceptable Windfarm grid layout concept


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Overall goalTo meet the total prize performance the overall goal for the park availability is set to 0.97That means that the goal for the turbine is 0.98 and the goal for the grid 0.99

Life cycle cost management methods for offshore wind turbine installations are given in [NRG,1999] and[NRG,2000]. A Reliability Program Plan should be the basis of all activities in order to arrive at minimumLife cycle costs. Its elements are:• Definition of preliminary reliability, availability & maintainability (RAM) requirements• Definition of program tasks• Procedures to evaluate status and control of tasks• Schedules including interrelations• Identification of known reliability problems, their impact and suggested solutions• Action item register• Milestones• Reliability demonstration (if any)• Procedures to monitor subcontractors• Software life-cycle planIn this note some comments are made with regard to the definition of preliminary RAM requirements andprogram tasks. The purpose is to show that handling RAM in the design phase is very feasible, resulting inminimum Life Cycle costs for the customer.

For a system consisting of serial components, every component failure results in a system failure. Forinstance, failure of the gearbox results in a turbine that is unavailable for production. System unavailabilitycan simply be approximated by the sum of component unavailabilities. System failures per hr can beapproximated by adding the component failures per hr. System reliability over a period is the product ofsystem failures per hr and period hours.

Failure estimation for the offshore grid

The grid calculations in Dowec will be based on these figures. Values may change due to additionalsupplier information. The reliability is higher than for turbine components, on the other hand theexpected repair time is longer for some of these components.

Description Failure/100km / pc

Time to repair

Connection on shore (150kV overhead lines, e.g.) 0.06 24hGrid connection point (switch board 4*150MVA) 0.02 24h3 end terminations 0.01 5hMain cables 4 * 150MVA to platform a 60km 0.3 21*24hPlatform switch 4* 0.02 *4 24hTransformer 150MVA 0.05 21*24hSecondary switchboards 0.02 *16 24hTurbine cabling 0.25 21*24hTurbine CCT 0.02 *100 24h

THESE VALUES ARE STIL OPEN FOR DISCUSSION AND ARE ONLY FIRST GUESSES /INDICATIONS

A program for rapid repair should be set up


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8.3. APPENDIX 3: HV GRID IN THE NETERLANDS

for more details see “http://www.tennet.org”


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8.4. APPENDIX 4: MEETINGS AND DOCUMENTATION LIST

1 Discussion meetings08-09-99 (Holiday-inn Utrecht)22-04-99 Energy Ned Arnhem05-07-99 NUON Arnhem

NLNLNL

2 DocumentsNetcode ( http://www.nma-dte.nl/) (http:// www.tennet.org )System codePrice information (http://www.apx.nl/)NUON Wind farm connection demands

Energy Ned: Technische aansluitvoorwaarden voor decentrale productieeenhedenInventory of grid connection demands NW62TC88/WG10 power quality aspects for wind turbines

Horns rev demandsElsam / Eltra requirements:ELT1999-411: Specifications for connecting Wind farm to the transmissionnetworkErganzungen zu den Netzanslussregeln von Windenergieanlagen (EON Netz)

NL Dte TR99-24 ( updated April 02)NL Dte TR99-24( updated April 02)NLNL

NL 050-jbz-R0012.docNL IEC/KEMA

DKDKDK

D3 Electrical integration of Windenergy ECN NL

4 Reports to DOWECKey issues regarding grid requirements DOWECGrid layout inventory of cost maintenance & relaibilityTop 10 of Grid demandsTerms of reference

NL KEMA 98460218-TDP 99-9076ANL 074-JBZ-R0127 ( working on)055-FG/JBZ-R0012045-FG-R0012.doc

5 Electriciteits distributie netwerken / Kluwer ISBN 90-5576-069-26 “http://www.tennet.org”7 Reliability analysis & specification DOWEC designs 13 maart 2000 Henk Wels Arnhem/NRG

8.5. APPENDIX 5: RESPONSIBLE ENGINEERS

DHR: J Bozelie NL/DK DHR: JTG Pierik (ed.) NL

FIRM: NEG Micon FIRM: ECN

http://www.nma-dte.nl/