6 Principles for Building Cost-Effective Wind Turbine Generators

6 Principles for Building Cost-Eff ective Wind Turbine Generators Dave Schaetz, Industry Technical Consultant, Alternative Energy, Rockwell Automation

and Steve Ludwig, Safety Programs Manager, Rockwell Automation

Aggressive state level renewable portfolio standards (RPS) are helping to reduce the nation’s

dependence on fossil fuel power generation and driving expansion of the wind industry in the

United States. The states of Colorado and California, for example, are aiming for 30 percent of

their energy to come from renewable energy sources including wind power by 2020. Seeing this

growth potential, wind turbine manufacturers around the world have their sights set on expanding

operations in the U.S. to satisfy the growing demand.

But a wind turbine manufacturer’s path for growth and expansion in new markets is not without

obstacles. Today’s challenges include establishing and managing an eff ective supply chain,

identifying and complying with relevant standards, improving the safety of workers and equipment

and remaining competitive as customers demand shorter time-to-market cycles.

Another challenge is remaining competitive

against other power generation sources.

Levelized Cost of Electricity (LCOE) is the

total lifecycle cost to build and operate a

plant over a period of time, divided by the

total electricity produced by that plant. Wind

turbine manufacturers can use LCOE as a

metric to compare the cost of generating

wind power with other technologies.

Continuously improving the design and

performance of wind turbines can help lower

the cost of electricity generated from wind.

Wind turbine manufacturers building

turbines for off shore applications face

an additional set of unique supply chain

and safety challenges associated with the

extreme, unpredictable environment.

Following are six leading principles for wind

turbine manufacturers who are expanding in

the growing U.S. market by delivering cost-

eff ective, safer equipment that is compliant

with appropriate standards.

Rockwell Automation Helps WTG

Manufacturer Manage its Supply Chain

Rockwell Automation helped WTG manufacturers get

through the economic recession by successfully managing

panel shipments. Outsourcing this activity reduced WTG

manufacturers’ fi nancial risk and eliminated the need to have a

dedicated assembly team for the project. Rockwell Automation

also helped WTG manufacturers manage their supply

chain to keep pace with production demands, especially as

manufacturing ramps up again.

For example, when a global

WTG manufacturer enlisted

Rockwell Automation to

build its control panels and

help manage its supply chain

and production worldwide,

Rockwell Automation

reached out leveraging its

best production practices

when building panels.

These include using detailed

and standardized work

instructions, identifying

and labeling raw material,

color coding air screwdrivers to match the color coding of screws

for proper torque settings, using safety and metrics boards

and eff ective lockout/tag out procedures. The company also

recognized Rockwell Automation for its technical innovation in

the design of a power distribution panel and for excellence in

on-time shipments.

2 | Building Cost-Eff ective Wind Turbine Generators

1. Establish a Global Supply Chain with Regional Experience

Wind turbine generator (WTG) manufacturers expanding operations in new markets may

encounter several supply chain challenges, including how to manage costs, inventory and vendor

relationships. When working with a reliable supply chain partner that can provide value add

services, such as electrical engineering, design and manufacturing, manufacturers benefi t from one

local point of contact for supply chain considerations, freeing up internal resources to focus on their

core competencies and lowering the total cost to design, develop and deliver new turbines.

A global supplier with broad industry experience also can help the WTG manufacturer implement a

successful production management system based on industry best practices and can help weather

economic downturns and boom/bust cycles that can be detrimental to smaller suppliers that only

focus on one or two industries.

WTG manufacturers partnering with a global supplier can leverage the supplier’s worldwide

manufacturing facilities, providing one point of contact for design, documentation management,

global coordination of assembly, and consistent quality of wiring, assembly and testing. Most

importantly, a global supplier’s distributor network helps ensure product availability and support.

The WTG manufacturer also can standardize component selection and panel design across all

locations worldwide, simplifying spare parts inventory, procurement methods, training and

staffi ng practices. Reducing the number of control platforms also helps ensure that there is always

a knowledgeable technician available because the manufacturer’s staff only needs training and

familiarity with one platform.

Finally, partnering with an outside vendor for supply chain management allows a WTG

manufacturer to eff ectively increase its production capacity without increasing its internal

workforce, allowing existing staff and resources to remain focused on the company’s core

expertise – designing the best WTG.

Building Cost-Eff ective Wind Turbine Generators | 3

2. Outsource Electrical Control Panels

Engineering the control panel is time-consuming and can have a signifi cant impact on system cost

for the WTG design and development process. One alternative to building control panels in house

is for WTG manufacturers to retain the design and documentation responsibilities, but work with

third-party panel builders to streamline the process. As business grows in new markets, working

with multiple panel builders can become quite arduous, often resulting in the need for increased

engineering and supply chain staff resources to coordinate and monitor multiple sources of supply.

A more effi cient alternative is for WTG manufacturers to work with a single automation supplier

that can design and build the entire panel – including all the control and power components –

and help standardize component selection and panel design across many locations worldwide.

This single point of contact through design, prototyping and ongoing deliveries can help a WTG

manufacturer increase production capacity without increasing its internal workforce, freeing up

existing resources that would be needed for engineering, procurement, inventory management,

testing, standards compliance and troubleshooting support.

A supplier with a testing/validation lab for environmental cycling and accelerated life testing

gives a WTG manufacturer the opportunity during the design phase to achieve the best possible

control panel design. This may lead to additional benefi ts such as reducing the panel size,

selecting components that generate less heat, and/or designing an integrated safety system

to help provide safe access to panels during operation. No matter which design strategies are

employed, a testing/validation lab can help a WTG manufacturer optimize the panel layout and

minimize troubleshooting.

By leveraging panel building services from a global supplier, a WTG manufacturer gains standards-compliant, custom, control and electrical distribution panels, such as the WTG control panel pictured here, while focusing time and internal resources on its core competencies.


3. Design for High Availability and Reliability

WTGs are used in extreme onshore and off shore environments. For example, the Tehachapi Pass,

California installation is in an extreme desert environment, and the proposed Cape Wind Nantucket

Sound installation is in the ocean – a potentially corrosive environment. A high level of availability

of the distributed power generation from WTGs is critical in both types of deployments. WTGs and

their equipment must be reliable when deployed in onshore and off shore environments, and spare

parts should be readily available in the event of failure.

In addition, lowering the Operating and Maintenance (O&M) costs during and after the warranty

period is important. Utilizing off -the-shelf components with long life cycles and leveraging a large

network of global support with access to spare parts inventory can help reduce system downtime

if a problem occurs.

Off shore wind turbines are increasingly used in a number

of countries because off shore winds tend to fl ow at higher

speeds than onshore winds, allowing turbines in off shore

environments to produce more electricity. Much of this

potential energy is near highly populated areas and energy

load centers where energy costs are high and land-based

wind development opportunities are limited.

Off shore turbines have unique technical needs because

weather conditions in off shore environments can be

extreme and fl uctuate more often than on land. Many

WTG manufacturers supplying off shore equipment try

to meet design challenges by engineering their own

solutions. These solutions can be susceptible to moisture

and contaminants resulting in short circuits and corrosion

of conductors and solder joints.

A better alternative, however, is to invest in components

specifi cally designed for these extreme environments and include them as part of a complete

control and information architecture, helping improve product longevity while reducing

integration and installation costs. For example, extreme environment products help to reduce

panel costs and the need for additional heating/cooling equipment, resulting in lower installation

and maintenance costs. Extreme environment products are often conformally coated to provide

environmental and mechanical protection which signifi cantly extends the life of the printed circuits

and electrical components.

Logix-XT controllers and Allen-Bradley FLEX I/O-XT™ products from Rockwell Automation are conformally-coated and designed using hardened components suited for rugged environments, without the additional installation and energy costs associated with auxiliary heating and cooling systems.


4. Conduct a Standards and Safety Audit

Safety is a critical element in WTG design and operation. Protecting people is most important,

and WTG manufacturers must also consider protecting the large capital investment in a WTG. The

diameter of wind turbine blades has become signifi cantly larger in recent years, and is now larger

than the wingspan of a Boeing 747 jumbo jet, increasing the potential amount of wind energy each

WTG is capable of producing. In turn, protecting assets becomes increasingly important for wind

turbine manufacturers.

Uncontrollable, hazardous weather

conditions like high wind speeds create

unique safety challenges for wind turbine

manufacturers. For example, the turbine

must be capable of stopping quickly and

safely in the event of high wind speeds

to prevent the turbine from tearing apart.

In addition, WTG safety system designers

are challenged with a mix of high and

low voltages, depending on the section

of the WTG (e.g., tower, nacelle, or hub).

Within each area, there may be low

voltages, high voltages or a combination

of the two. The voltage dictates the

safeguarding mechanisms necessary

to mitigate risks in each area of the WTG

(See Figure 1).

Personnel must be protected against rotating parts in the nacelle and hub, and WTG designers may

need to use physical guarding or special access requirements to stop the WTG from rotating prior

to personnel entering the area. Other examples of eff ective safeguarding include employing a safe-

speed monitoring relay to detect over speed of the rotor, vibration monitoring sensors to detect

excess vibration, switches to control the opening of control cabinet doors, and/or medium voltage

switchgear used in the lower portion of the tower to detect and suppress arc fl ash hazards.

Automation suppliers will continue to validate and test solutions for mitigating arc fl ash hazards

through new wind turbine power cabinet designs. Continuing to develop arc fl ash resistant

solutions by leveraging control components will help WTG manufacturers more eff ectively mitigate

the risks associated with arc fl ash energy in the future.

As the diameter of a wind turbine increases so does the potential to increase wind energy production. An outline of a Boeing 747 jumbo jet is shown here against an off shore WTG to illustrate the size of the blades.


Performing a safety audit before control system design helps engineers chart the course for an

eff ective safety solution and evaluate risks early in the development process. This saves critical time

and helps machine builders get their equipment to market faster. In addition, the machine’s end

users gain optimized production, thanks to an automation system that helps operate machinery

and processes in the most effi cient way. A safety audit identifi es potential hazards and the

required safety control system integrity level, and helps guide the selection of the overall control

architecture to achieve the optimum level of safety.

Where hazards cannot be removed through design, machine builders typically will install a fi xed

physical barrier that helps protect users from the hazard. When frequent access to the hazardous

area is required, non-fi xed guards are used, such as removable, swinging or sliding doors. In areas

where non-fi xed guards are impractical, guarding solutions that monitor the presence of the

operator rather than the status of the gate can be used.

Figure 1 (Source: Rockwell Automation)


5. Provide Compliance to Regional Electrical and Safety Standards

As WTG manufacturers expand operations globally, they must adhere to local and regional

standards to help ensure the safety of workers and equipment in those regions. By following

appropriate international standards, WTG manufacturers can streamline production processes

globally, and gain access to customers all over the world. As an added bonus, incorporating

standards into the wind turbine design process can increase productivity and profi tability for both

manufacturers and operators of wind turbines.

Some of the newest standards that are reshaping how designers approach wind turbine projects

pertain to safety:

International Organization for Standardization (ISO) 13849-1/2 and International

Electrotechnical Commission (IEC) 62061. These international safety standards were recently

mandated by the European Commission’s Machinery Directive, and issued in part to assist

with the free movement of goods and services across a single European market. They also are

considered among the most rigorous machine safety standards in the world. Wind turbines

fall under the scope of the Machinery Directive, and therefore any WTGs shipped into or out

of Europe must comply with the appropriate standard after the fi nal withdrawal of EN 954-1

in 2011. (See fi gures 2 and 3.)

Figure 2 (Source: Guide to application of the Machinery Directive 2006/42/EC 2nd Edition June 2010, pages 28-29)

Figure 3 (Source: Guide to application of the Machinery Directive 2006/42/EC 2nd Edition June 2010, pages 28-29)

The international standards add two very important elements to the reliability of the

machine’s safety function: time and risk. These two elements help machine builders take

advantage of a more methodical approach to safety system design.

Both international standards require WTG manufacturers to identify and document the

potential hazards associated with machine operation and the risk levels present to users.

The safety system is then designed to the level of risk associated with the hazards present

on the machine. Because appropriate documentation proves a machine’s level of safety,

designers can better justify a need for a safety system upgrade, and operators can be more

confi dent in the reliability of a machine’s safety system.

The moving parts of machinery are powered by a drive system using one or more sources of energy such asthermal, electric, pneumatic, hydraulic or mechanical energy. The machinery may have a motor using its ownsource of energy such as thermal energy or energy provided by a battery. It may be connected to one ormore external sources of energy such as a supply of electricity or compressed air. Machinery may use mechanical energy supplied by other equipment such as, for example, towed agricultural machinery that isdriven by the power take-off of a tractor, or test beds for motor vehicles that are driven by the vehicles beingtested; machinery may also be powered by natural sources of energy such as wind or water power.

Article 2 (a) – fi rst indent

‘machinery’ means:

– an assembly, fi tted with or intended to be fi tted with a drive system other than directly applied human or animal effort, consisting of linked parts or components, atleast one of which moves, and which are joined together for a specifi c application.


Electromagnetic Compatibility (EMC) Directives. EMC management has emerged as a critical

means of improving the reliability and operating life of electronic equipment employed

in WTGs. EMC directives aim to help ensure that all electrical devices in one electrical

environment work properly and safely together. Specifi cally, the EMC Directive (2004/108/EC)

requires that the electromagnetic disturbance generated by any fi xed installation does not

exceed the level above which radio and telecommunications equipment or other equipment

cannot operate as intended. Under this directive, WTGs are considered fi xed installations, and

therefore must be built according to the engineering practices outlined in the directive. (See

Figures 4 through 7.)

Figure 4 (Source: Guide for the EMC Directive 2004/108/EC February 8, 2010, page 21)



Figure 7 (Source: Directive 2004/108/EC of the European Parliament and of the Council of December 15, 2004 on the approximation of the laws of Member States relating to electromagnetic compatibility and repealing Directive 89/336/EEC, page 8)

“Fixed installation” means a particular combination of several types ofApparatus and, where applicable, other devices, which are assembled,installed and intended to be used permanently at a predefi ned location.

Examples of fi xed installations:Industrial plants, power plants, power supply networks, telecommunicationnetworks, cable TV networks, computer networks, airport luggagehandling installations, airport runway lighting installations, automaticwarehouses, skating hall ice rink machinery installations, storm surgebarrier installations (with the control room etc), wind turbine stations, carassembly plants, water pumping stations, water treatment plants, railwayinfrastructures, air conditioning installations.

Owing to their characteristics, fi xed installations are not subject to the needfor free movement within the Community. Therefore, they are not subject to the requirements for CE marking, DoC or for formal EMC assessmentbefore putting into service. However, fi xed installations have to comply with the protection requirements and other specifi c requirements (Annex I of the Directive) which are applicable to them.

ANNEX I

ESSENTIAL REQUIREMENTS REFERRED TO IN ARTICLE 5

1. Protection requirements

Equipment shall be so designed and manufactured, having regard to the state of the art, as to ensure that:

(a) the electromagnetic disturbance generated does not exceed the level above which radio and telecommunicationsequipment or other equipment cannot operate as intended.

(b) it has a level of immunity to the electromagnetic disturbance to be expected in its intended use which allows itto operate without unacceptable degradation of its intended use.

2. Specifi c requirements for fi xed installations

Installation and intended use of components

A fi xed installation shall be installed applying good engineering practices and respecting the information on the intended use of its components, with a view to meeting the protection requirements set out in Point 1. Those goodengineering practices shall be documented and the documentation shall be held by the person(s) responsible at thedisposal of the relevant national authorities for inspection purposes for as long as the fi xed installation is in operation.


Product Directives. Many product directives have been issued in Europe as part of an eff ort

to create a unifi ed European market. Limited to “essential requirements,” which are general

in nature and primarily focus on health protection, these directives are compulsory for any

product put into circulation and so apply to wind turbines and their sub-assemblies.

GL Guideline for the Certifi cation of Wind Turbines (Edition 2010). The latest edition of this

guideline makes specifi c references to the EN ISO 13849-1: 2006 Functional Safety Standard

and requires that WTG manufacturers conduct a risk assessment to determine the maximum

permitted probability of failure. By providing numerical evidence of the probability of failure,

WTG manufacturers can help justify a customer’s investment in new safety systems. WTG

manufacturers must follow ISO 13849-1: 2006 and IEC 60204-1 to gain GL certifi cation of a

WTG. GL publishes guidelines for certifying WTGs. (See Figure 8.)

Figure 8 (Source: GL Guideline for the Certifi cation of Wind Turbines, July 2010, Figures 2.1.4 “Required risk reduction through protection functions,” 2.2.3.3 “Safety System,” and 2.3.2.15 and 2.3.2.15.2 “Emergency stop requirements”)


Underwriters Laboratories, Inc. (UL) Standards. Large and small WTGs are evaluated

according to UL Subject 6140-1, UL’s “Outline of Investigation for Wind Turbine Generating

Systems.” The systems are evaluated for risk of fi re and shock, including safety-related control

system electrical performance and utility grid-interconnect performance for utility interactive

models. While these standards apply in North America, they do not align directly with many of

the European IEC standards, making it diffi cult for European WTG manufacturers to conform to

standards when expanding to the U.S.

Certifi cation (CE) Markings. Similar to UL Standards in North America, a CE marking denotes a

product’s compliance with European standards. A CE marking symbolizes that the equipment

conforms to the applicable requirements imposed on the manufacturer. WTG manufacturers

need to earn a CE marking on any WTG so it can be shipped throughout Europe.

Tackling the many, often complex, standards can be daunting. WTG manufactures should leverage

the expertise of certifi ed safety consultants from a global supplier to navigate requirements and

design an acceptable safety system.


6. Integrate WTG Safety into the Control System Design to Reduce Complexity

The evolution of safety standards and economic factors are driving the evolution of safety systems

from hardwired to contemporary, highly integrated confi gurations. Using an integrated platform

for safety and standard control eliminates the need for electromechanical or hardwired controls.

The more designers integrate the standard and safety control functions of a system, the better

the opportunity to reduce equipment redundancies, improve productivity and minimize costs.

See Figure 9 for how standard and safety control systems should interact in a WTG.

This integrated control functionality reduces the number of unique components in use as part

of the WTG control system, which in turn reduces inventory costs, as well as maintenance team

training requirements. End users also benefi t from less waste with fewer parts to maintain and

replace throughout the WTG life cycle. In addition, integrated control systems, having broader

intelligence regarding machine operation and status, reduce nuisance shutdowns and prolonged

restarts, further improving machine effi ciency and productivity.

Safety controllers provide this integrated control functionality and off er signifi cant benefi ts in

multistep shutdown or ramp-down sequences because they provide the necessary logic through

software rather than the hard-wired logic of relays. An integrated safety controller is an ideal

solution for any application requiring advanced functionality, such as zone control. Being able

to monitor and control access to what is active on each level of the WTG is critical due to the size

and height of the decks within a WTG tower design. With properly designed safety controls and

guarding, designers reduce access time, helping make machines safe and effi cient.

Along with eliminating the need for a separate safety controller, integrated safety systems also

use a single programming software package. This can eliminate the need to write and coordinate

multiple programs on diff erent controllers, which in turn can simplify application programming and

help reduce training and support costs. See Figure 10 for an illustration of how standard and safety

functions are integrated into a single control solution.

Figure 9 (Source: Rockwell Automation and GL Edition 2010)

Publication OEM-WP010A-EN-P – September 2011 Copyright ©2011 Rockwell Automation, Inc. All Rights Reserved. Printed in USA.

Safe-speed control solutions provide a great example of eff ective control integration. With

safe-speed control, safety input devices, such as guard-locking switches and emergency stop

pushbuttons, connect directly to the speed-monitoring core of the control solution. This eliminates

the need for a separate, dedicated safety controller. Extending use across multiple platforms, safe-

speed control solutions help reduce overall system cost and improve fl exibility because they allow

operators to perform maintenance and other tasks while a machine is in motion. Safe-speed control

also helps increase uptime and decrease energy costs because a machine need not be completely

shut down and then restarted.

Networking off ers another way to integrate safety and standard controls. The introduction of

networks to industrial environments helps increase productivity, reduce wiring and installation,

improve diagnostics and ease access to facility data. Using an existing network to include safety

information extends those same benefi ts, allowing seamless communication of the complete

automation process on one standard network with one set of hardware and wiring. Diagnostics from

smart devices that are networked together also can simplify designs and reduce integration costs.

On the Horizon

Thanks to advancements in technology and globalization of safety standards, WTG manufacturers

can expand to new markets and help customers improve worker safety and protect equipment

and assets. By enlisting the help of global suppliers, WTG manufacturers can provide a smooth

expansion to new markets and continue growing as the wind energy industry expands.

Figure 10 (Source: Rockwell Automation) An Allen-Bradley GuardLogix PAC from Rockwell Automation incorporates standard and safety control in one controller.

Allen-Bradley, FLEX I/O-XT and GuardLogix are trademarks of Rockwell Automation, Inc.Trademarks not belonging to Rockwell Automation are property of their respective companies.

6 Principles for Building Cost-Effective Wind Turbine Generators

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