Optimizing Energy Yield in Multi-MW Power Converters for Wind by Mikel Zabaleta, Ingeteam Wind...

OPTIMIZING ENERGY YIELD IN MULTI-MWPOWER CONVERTERS FOR WIND

Bremen, 30th November 2015

Speaker: Mikel ZabaletaMV-Wind Product [email protected]

INDEX

• Scenario

• Introduction

• Conclusions

• Converter arrangements for multi-MW turbines

• Ingeteam’s solution

• Efficiency effect on energy yield

• Modularity effect on energy yield

OPTIMIZING ENERGY YIELD IN MULTI-MW POWER CONVERTERS FOR WIND

Introduction

Scenario

Modularity

Conclusions

Converter arrangements

Ingeteam’s solution

Efficiency

Introduction

The following terms and acronyms have been used along the presentation:• Conversion line: is the association of inverters in a back to back topology

characterized by the fact that a failure in any of its semiconductors, lead to

the total shutdown of it.


Introduction

Scenario

Modularity

Conclusions



Efficiency

Introduction

• Conversion stage: is the association of conversion lines in parallel to form

a higher output power unit.

• Corrective period: is the elapsed time between the occurrence of an

event and the maintenance actions performed to restore it. If a failure

occurs on Monday but the service personnel can not access to fix it until

Friday, the corrective period would be 5 days..


Introduction

Scenario

Modularity

Conclusions



Efficiency

Introduction

• PTF (Probability To Fail): indicates the probability that has a component

or subsystem to fail during one year of operation. This indicator is inherent

to the component itself and to the application requirements.

• PTS (Probability To Stop): indicates the probability that has a component

or subsystem to cause a full shutdown of the conversion line (or stage),

that includes it, during one year of operation. In this indicator, it affects not

only the component, but also the level of redundancy. If there is no

redundancy, PTS=PTF.

• MAEP (Mean Annual Energy Production): is the ratio between the actual

energy produced by the conversion stage and the maximum that have

been available in the site.


Introduction

Scenario

Modularity

Conclusions



Efficiency

Description of the Scenario

The study considers a 8 MW power stage for a windturbine with the rated

power curve shown on the next figure. It has a cut in and cut out speed of 3

and 26 m/s respectively.

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Pow

er [k

W]

Wind speed [m/s]

Power curve


Introduction

Scenario

Modularity

Conclusions



Efficiency


The base site mean wind-speed is considered 7 m/s (3863 equivalent hours).

The wind speed distribution is fitted to a Weibull distribution with form factor of

2.

0,00%

2,00%

4,00%

6,00%

8,00%

10,00%

12,00%

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28Wind speed [m/s]

Wind speed probability


Introduction

Scenario

Modularity

Conclusions



Efficiency


Other considerations are:• The standard corrective period is considered to be 1 month.

• The windturbine lifetime is 30 years.

• The price for the MWh has been considered 200 euros for the sake of

simplicity

• The PTF of each conversion line is calculated to be 18%

• The PTF of the converter controls is calculated to be 4%

• The PTF of the converter cooling is calculated to be 2%

• The cost of a maintenance access is estimated to be 15 k€

The analysis will cover the following parameter deviations:

• Efficiency: from 97 to 98%

• Corrective period: from 1 to 8 [Days], 1 to 4 [Weeks], 1 to 12 [Months]

• Mean Wind Speed: from 5 to 8 m/s


Introduction

Scenario

Modularity

Conclusions



Efficiency

Efficiency effect on energy yield

A lot of importance has been assigned to the efficiency of the conversion

stage in the past. This obviously affects the energy harvested by a

windturbine, but its effect is not straightforward.

The efficiency of the conversion stage only affects during partial loads

operation (during the maximum power tracking MPT);

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

0,00%

2,00%

4,00%

6,00%

8,00%

10,00%

12,00%

14,00%

16,00%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27Wind speed [m/s]

5 m/s 6 m/s 7 m/s 8 m/s Power curve

Mean Wind Speed Probability in MPT5 m/s 71%6 m/s 71%7 m/s 66%8 m/s 60%9 m/s 54%

10 m/s 48%


Introduction

Scenario

Modularity

Conclusions



Efficiency

Efficiency effect on energy yield

Generally, as the mean wind speed of the site increases, the effect of the efficiency of the conversion stage becomes less important as less partial load hours are probable.

0,00%

0,10%

0,20%

0,30%

0,40%

0,50%

0,60%

0,70%

0,80%

0,90%

1,00%

5 5,5 6 6,5 7 7,5 8 8,5 9 9,5 10

MAE

P

Mean wind speed [m/s]

MAEP improvement for a 1% efficiency step

One conversion line Two conversion line


Introduction

Scenario

Modularity

Conclusions



Efficiency

Modularity effect on energy yield

The modularity also affects the MAEP because when a failure occurs in the

conversion stage, it may stop it shutting down the entire production (in the

case of a single conversion line) or it may reduce the available output power

(in the case of two or more conversion lines).

Here is where the corrective period plays its role.

1 2 3 4 5 6 7 8One conversion line 99,94% 99,87% 99,81% 99,74% 99,68% 99,61% 99,55% 99,48%Two conversion line 99,95% 99,90% 99,85% 99,79% 99,74% 99,69% 99,64% 99,59%Three conversion line 99,95% 99,91% 99,86% 99,81% 99,76% 99,72% 99,67% 99,62%Four conversion line 99,96% 99,91% 99,87% 99,82% 99,78% 99,73% 99,69% 99,64%

99,40%

99,50%

99,60%

99,70%

99,80%

99,90%

100,00%

MAE

P

Maintenance Access [Days]


Three conversion line Four conversion line


Introduction

Scenario

Modularity

Conclusions



Efficiency


If the corrective period is in the weeks timeframe,

1 2 3 4One conversion line 99,51% 99,03% 98,54% 98,06%Two conversion line 99,61% 99,23% 98,84% 98,45%Three conversion line 99,65% 99,29% 98,94% 98,59%Four conversion line 99,66% 99,33% 98,93% 98,57%

97,0%

97,5%

98,0%

98,5%

99,0%

99,5%

100,0%

MAE

P

Maintenance Access [Weeks]




Introduction

Scenario

Modularity

Conclusions



Efficiency


If the corrective period is in the months timeframe,

1 2 3 4 5 6 7 8 9 10 11 12One conversion line 98,06% 96,11% 94,17% 92,22% 90,28% 88,33% 86,39% 84,44% 82,50% 80,56% 78,61% 76,67%Two conversion line 98,45% 96,91% 95,36% 93,82% 90,89% 89,06% 87,24% 85,42% 83,59% 81,77% 76,89% 74,79%Three conversion line 98,59% 96,90% 95,35% 93,25% 91,56% 89,05% 87,22% 84,29% 82,33% 76,21% 73,83% 69,79%Four conversion line 98,57% 96,96% 95,16% 93,19% 90,22% 87,73% 85,05% 80,89% 77,69% 72,68% 67,16% 59,76%

60,00%65,00%70,00%75,00%80,00%85,00%90,00%95,00%

100,00%105,00%

MAE

P

Maintenance Access [Months]




Introduction

Scenario

Modularity

Conclusions



Efficiency

Conclusions

• The effect of the efficiency (only at partial loads!!) on the MAEP

decreases with the mean wind-speed of the site.

• The modularity, in conjunction with the corrective period, has the strongest

influence on the MAEP. Here, the cost of the maintenance access should

also be taken into account (15 k€).

NOL 75% NOL 66% NOL 50% NOL 33% NOL 25% NOL 0%

Annual Energy [MWh] MAEP

Extra Annual Income (discounted

maintenance) [€]

One CL 0 0 0 0 0 7 30304 98.056% 0

Two CL 0 0 10 0 0 2 30455 98.545% 26640

Three CL 0 16 0 0 0 2 30468 98.588% 25166

Four CL 22 0 1 0 0 2 30462 98.568% 19674

• The extra annual income (for 2 CL) is even higher when including

redundancies in the control system (in CPU, in power supplies) reaching

above 44k€.


Introduction

Scenario

Modularity

Conclusions



Efficiency

Conclusions

• Comparing the four conversion stages regarding some design drivers, it

can easily be seen how a two conversion line solution is optimal.En

ergy

har

vest

Initi

al c

ost

Foot

prin

t and

w

eigh

t

Uns

ched

uled

mai

nten

ance

ac

cess

es

Mul

tiple

sou

rces

fo

r com

pone

nts

One CL LOW HIGH HIGH LOW LOW

Two CL HIGH MEDIUM MEDIUM MEDIUM HIGH

Three CL HIGH HIGH HIGH HIGH HIGH

Four CL HIGH HIGH HIGH HIGH HIGH


Introduction

Scenario

Modularity

Conclusions



Efficiency

Power converter arrangements for multi-MW windturbinesIn the multi-MW range, several different converter arrangements can be

found:

• In low voltage (LV), three or more 2L conversion lines are usually needed

to reach output power.

• In medium voltage (MV), basically two different trends appear:

• Press-pack based converters which reach the output power with only

one 3L conversion line,

• HV-IGBT based converters which usually require the parallelization of

two (or three) 3L conversion lines.

As it has been seen before, a two conversion lines stage is optimum from the

energy harvest point of view and the operational costs.

Some internal and external [1] studies have highlighted that a reduction in the

CoE between 2-4% can be achieved with MV power stages in the multi-MW

range.[1] W. Erdman and M. Behnke, Low Wind Speed Turbine Project Phase II: The application of Medium-Voltage Electrical Apparatus to the Class of Variable Speed Multi-Megawatt Low Wind Speed Turbines. Golden, CO, USA: National Renewable Energy Lab. (N.R.E.L.), 2012


Introduction

Scenario

Modularity

Conclusions



Efficiency

Ingeteam’s solution for multi-MW windturbines

The MV product family has been designed with the following driversMaximize energy harvest,

Minimize initial cost,

Minimize footprint and weight,

Scheduled maintenance intervals greater than one year,

Minimize unscheduled maintenance accesses,

Reduced MTTR,

Multiple sources for components

Harsh environment withstand

These has led to the following solutionHV-IGBT based converter (reduced MTTR, multiple sources, reduced initial cost, footprint and

weight)

Two conversion lines (High energy harvest, low initial cost)

Oversized key components and redundancies in control and cooling systems (higher energy

harvest, increases maintenance intervals and minimizes unscheduled maintenance)

Fully closed (IP54+) water-cooled cabinets (high immunity against aggressive atmospheres)

Key design drivers


Introduction

Scenario

Modularity

Conclusions



Efficiency


Three products are available depending on the required output:

INGECON WIND MV100 3400 -> 635 Arms with overload 700 Arms



Arranging two conversion lines of each type, the following output power can be reached:

2 CONVERSION LINES ARRANGEMENTGRID MACHINE

Target WT power [kW] simultaneity

0,9/0,9


0,9/0,95


0,95/0,95

Target WT power [kW] Vn@PF=1

Target WT Power [kW] Vn@PF=0,95

INGECON WIND MV100 56009100 9600 10100 11200 11400

10000 10600 11200 12400 12500

INGECON WIND MV100 46007500 7900 8300 9200 93008300 8700 9200 10200 10300

INGECON WIND MV100 34005500 5800 6100 6800 68006200 6500 6900 7600 7600

PERMANENT POWER

OVERLOAD


Introduction

Scenario

Modularity

Conclusions



Efficiency


The power stack is based on small “bricks” called Basic Power Modules

(BPMs).

These modules contain the semiconductor devices (HV-IGBTs) and its

ancillary systems (drivers, cooling, temperature probes, etc.) of a 3L-NPC

phase leg.

The BPMs are assembled on sliding guides helping to obtain and extremely

reduced MTTR (less than 30 minutes).

Two BPM modules (sharing the electromechanical design) cover all the range

of powers required by means of changing the semiconductor devices

(matching its ratings).


Introduction

Scenario

Modularity

Conclusions



Efficiency


The engineering cabinet includes:The grid side and machine side reactors

The internal cooling system

The dVdt filter (for 1,5 kV/us)

The precharge and discharge system

The grid side and machine side contactors

The machine side voltage measurements

The machine side manual disconnector and grounding

The DC-bus grounding disconnector

Grid side and machine side surge protections

Three different engineering cabinets are available to optimally fit all the

targeted output powers. These share the basic design (the components

layout) and differs in the size of certain components.

Engineering


Introduction

Scenario

Modularity

Conclusions



Efficiency


Control electronics accessible from outside

Inspection windows

Engineering


Introduction

Scenario

Modularity

Conclusions



Efficiency


WCU BPMs 1 ENG 1 BPMs 2 ENG 2 GSF

Thank you for your attention

Any questions??

Date post:	08-Apr-2017
Category:	Engineering
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