Established in 1948 to support new hydroelectric development on the Columbia River, HDC is the Corps of Engineers' National Center for Expertise in hydroelectric and large pumping plant engineering services. Administratively a part of the Portland District, our office is in downtown Portland, Ore.

Vision

• Leaders in Hydropower Engineering
• Respected for our competence
• Responsive to customer needs
• Reliable product delivery

Goals

People: Attract, maintain and develop people to deliver technical excellence in hydropower design.
Customer Satisfaction: Know them, earn trust and achieve desired outcomes while balancing technical issues.
Technical Quality: Deliver products that meet internal and industrial standards.

Army's Civilian Personnel On-Line
Army's VacancyAnnouncements  From this page you may view open announcements and self-nominate for vacancies for which you want to be considered.
Army's Resume Builder and ANSWER
Use the Resume Builder to enter your resume into the Army's CentralizedResumix System and provide supplemental data to indicate your qualifications and preferences. After your resume is submitted, it is used with other staffing tools to recruit and place applicants.
Use the ANSWER tool allows users to check the status of their resume, track their application history, view self-nomination history and view their current resume and supplemental data in the Central Resumix Database. Users may toggle between the Resume Builder and ANSWER.
For questions regarding work requirements, pay and benefits, or help with application procedures for vacancies in the Hydroelectric Design Center, please contact us at (503) 808-4203.

The Engineer In Training program consists of structured education related to hydroelectric power design and construction across the nation, Corps of Engineers activities throughout the Northwest, and the mission of the Portland District. The program is carried out over an 18-month time period through rotating assignments to various offices primarily within the Portland District and around the Corps. The following brochure provides further information about the EIT program.Engineer In Training Brochure (PDF, 722 KB)

The Electrical branch is responsible for providing planning and engineering for electrical portions of powerhouses and pumping stations. This includes the review of electrical features of non-Federal hydropower development at Corps projects that could affect the project integrity and safety, as well as forensic failure analysis for major power plant equipment. Its four major sections are:

1. Controls& Protection Systems
2. Power Systems
3. Generation Equipment
4. Generic Data Acquisition & Controls System Support Section

These four sections provide a full range of professional engineering services in support of the general systems listed below. Included are the engineering studies for load flow, fault analysis, arc flash analysis, relay settings, equipment sizing, and control interactions with the external power transmission system. Field engineering support is also provided to assist operating power plants, and to test and support energization for commissioning and start-up of new or renovated systems.

The Mechanical/Structural branch is responsible for providing, planning and engineering for mechanical and structural portions of powerhouses and pumping stations. In addition, this branch provides reviews of structural and mechanical features of non-Federal hydropower at Corps projects that could affect the project integrity and safety.
The Mechanical/Structural Branch has four sections:

1. Engineering Support
2. Turbo-Machinery
3. Mechanical System
4. Structural

The Product Coordination branch at HDC works with both customers and engineers, managing HDC's workload and holding everything together, while maintaining positive and successful customer relationships for HDC. Product coordinators act as a primary point of contact for customers and see each project through from the beginning of work until the project is completed, and are assigned work areas by division across the nation. (See: Work region divisions.)
The PC branch does the following work:

• Coordinate and prepare scopes, schedules and budgets for each task or job.
• Monitor schedules and costs and assure effective progress of jobs.
• Interface with client district's project managers.
• Finalize specification packages.
• Coordinate with customer districts and partners to help develop out-year programs.
• Represent HDC in meetings with customers, partners, stakeholders and interested parties.
• Assist management and resource providers in assessing resourcing and staffing needs.

There are three work regions divisions: Pacific, Central and Atlantic, which cover the following Corps districts:

Pacific:

Northwestern Division(CENWD)

1. Portland District (CENWP)
2. Seattle District (CENWS)
3. Walla Walla District (CENWW)

Pacific Ocean Division(CEPOD)

1. Alaska District CEPOA)
2. Honolulu District (CEPOH)

South Pacific Division (CESPD)

1. Albuquerque District (CESPA)
2. Los Angeles District (CESPL)
3. Sacramento District (CESPK)
4. San Francisco District (CESPN)

Central:

Great Lakes and Ohio River Division (CELRD)

1. Buffalo District (CELRB)
2. Chicago District (CELRC)
3. Detroit District (CELRE)
4. Huntington District (CELRH)
5. Louisville District (CELRL)
6. Nashville District (CELRN)
7. Pittsburgh District (CELRP)

Mississippi Valley Division (CEMVD)

1. Memphis District (CEMVM)
2. New Orleans District (CEMVN)
3. Rock Island District (CEMVR)
4. St. Louis District (CEMVS)
5. St. Paul District (CEMVP)
6. Vicksburg District (CEMVK)

Northwestern Division (CENWD)

1. Kansas City District (CENWD)
2. maha District (CENWO)

Southwestern Division (CESWD)

1. Ft. Worth District (CESWF)
2. Galveston District (CESWG)
3. Little Rock District (CESWL)
4. Tulsa District (CESWT)

Atlantic:

Headquarters (HQUSACE)
Washington DC - R&D Programs
North Atlantic Division (CENAD)

1. Baltimore District (CENAB)
2. New England District (CENAE)
3. New York District (CENAN)
4. Norfolk District (CENAO)
5. Philadelphia District (CENAP)

South Atlantic Division (CESAD)

1. Charleston District (CESAC)
2. Jacksonville District (CESAJ)
3. Mobile District (CESAM)
4. Savannah District (CESAS)
5. Wilmington District (CESAW)

The Hydropower Analysis Center was established in the 1950s to address the huge hydropower potential of the Pacific Northwest.

In 1995, the HAC became the U.S. Army Corps of Engineers' center of hydropower expertise.

In January 2008, the HAC was merged with Hydroelectric Design Center. HAC has been involved with hydropower analyses and economic evaluations of many projects in the U.S. and abroad.

HAC frequently works closely with HDC to incorporate both technical and economic analysis in the design of power-generating facilities.

Analysis of the hydropower benefit component in cost allocation studies for multi-purpose water resource projects. Conduct water storage reallocation studies which require the identification of power benefits and revenue forgone with reallocation of storage for municipal use and industrial water supply withdrawals.

HartwellProject in Georgia

Laurel and J. Percy Priest projects in Tennessee

The White River System in Arkansas

The staff of the HSA MCX have been involved in numerous committees to develop policy and procedures for planning and analysis of hydropower. Examples of these committees include the Water and Energy Task Force, National Hydropower Study and others.

Conduct analysis in support of a wide variety of other powerplant studies.Included are studies such as:
Environmental/Fishery studies - Analysis of the effects of modifications in project operations, project changes for environmental/fishery reasons (e.g., fish screens, fishbypass systems, & water quality improvement facilities, etc.)
Generator Rewind & Uprate studies - Dexter Rewind Study in Oregon.
Plant Expansion studies: Feasibility analysis for expanding the generation capabilities at existing power plants or adding new generation at non-power projects.

Rehabiliation studies: Analyze hydropower output and provide economic evaluations in support of a full range of powerplant equipment rehabilitation studies (e.g., generator rewind and uprate studies, turbine replacement and refurbishment studies, and peripheral electrical equipment studies).

Dardanelle - Powerplant in the southwestern U.S.

Garrison - Powerplant in the midwestern U.S. on the Missouri River.

Hartwell, John H. Kerr, and J. Strom Thurmond - Powerplants in the southeastern U.S.

Ice Harbor - Ice Harbor powerplant in the Pacific Northwest.

The Dalles - The Dalles powerplant.

Computation of energy and/or capacity values to be used in power benefit analysis. Power System Production Cost Models such as PROSYM, POWRSYM, and PC-SAM are maintained for areas throughout the country to allow the MCX to provide power values for all regions. The MCX provides coordination with the Federal Energy Regulatory Commission (FERC) and Federal Power Marketing Agencies. These values are combined with energy and capacity data to determine power benefits.

MCX simulation models.

Conduct power system studies and economic analysis on major river and power systems.

Climate Change Action Plan - Corps-wide climate change action plan.

Review of ACT-ACF - Review of the Alabama-Coosa-Tallapoosa and Apalachicola-Chattahoochee-Flint systems for Mobile District.

System Operation Review - System Operation Review for the Northwestern Division for the Columbia River system.

The HSA MCX can provide training for others on all aspects of hydropower analysis and economic evaluation of hydropower projects. This has been provided within the Corps as well as outside of the Corps and for representatives of foreign countries.

The Corps of Engineers is a major command of the U.S. Army, and is as old as the U.S. In the early 1820s, Congress directed the Chief of Engineers to begin clearing a navigation channel on the Ohio and Mississippi Rivers. Today the Corps is responsible for a wide-ranging number of water resources uses, including navigation, flood damage reduction, irrigation and water supply, recreation and hydropower.

Power and the U.S.

This pie chart indicates the percent distribution of power generating capacity in theU.S., of which fossil fuels (primarily coal-fired steam) are the major source ofenergy. "Others" refers to wind, solar and geothermal power.

Hydropower and the Corps

The Corps is the single largest owner and operator of hydropower facilities in the U.S. We have 75 power projects, totaling 375 units. The pie chart below indicates the distribution of hydropower-generating capacity in the U.S.

Corps Hydropower Capacity by Division

The following pie chart shows the distribution of capacity among the various divisions in the Corps. Most U.S. hydropower production is in the Pacific Northwest.

The U.S. Army Corps of Engineers is the largest operator of hydroelectric power plants in the U.S., and one of the largest in the world. The 75 Corps plants have a total installed capacity of 20,474 megawatts and produce nearly 100 billion kilowatt-hours a year. Nearly a third of the nation’s total hydropower output, it's enough energy to serve about ten million households, or roughly ten cities the size of Seattle, Wash.

Hydropower offers numerous advantages over alternative fuels:

• RenewableThe earth provides a continual supply of water from rainfall and snowmelt.
• EfficientHydropower plants convert about 90 percent of the energy in falling water into electricity.
• CleanHydropower plants do not emit waste heat and gases.
• ReliableHydropower machinery is relatively simple, which makes it reliable and durable.
• FlexibleUnits can start quickly and adjust rapidly to changes in electricity demand.

Corps hydropower plants play a key role in the economy by offering an affordable power source, which helps keep overall energy prices down. Because they don't use fossil fuels Corps hydropower plants also are better for the environment than other sources of electrical power. Without hydropower, the U.S. would have to burn much more coal, oil, and natural gas every year. The increasing availability of hydropower also helps reduce America's dependence on other nations for fuel.
The Corps collaborates on its hydropower efforts with the Department of Energy and a variety of other federal, regional and state agencies and private companies. The Corps is in the process of upgrading many of its facilities to increase efficiency and reliability.
Learn more from the Hydropower brochure (pdf 1.64 MB).For more information, click here.

The Corps has 375 main generating units, plus a number of "house units" that only provide power to run the internal systems of our powerhouses (these arecalled "Station service Units"). Our smallest units are 1 megawatt or less, butmost of our units are very much larger, up to our largest unit which can produce220 megawatts. Our powerhouses range from having a single small generating unit,up to having to 27 huge units (the powerhouse at that plant is nearly a halfmile long!). All together our units have the capability to generate 21,000megawatts--making the Corps of Engineers the largest producer of hydroelectricpower in the US. If 21,000 megawatts sounds like a lot of power, it is! Read onto see just how much.

A Relative Example

The basic unit of measure for electrical power is the watt. Everyone is familiar with what a 100-watt light bulb looks like. A 100 watt bulb consumes100 watts of electrical power when operating; 10 bulbs consume a total of 1000 watts to operate. 1000 watts is the same as 1 kilowatt (kilo is the metric word for 1000), which is abbreviated as 1 kW.
The basic unit of measure for electrical energy is the kilowatt-hour (abbreviated as kW-hour). The 10 light bulbs, when left on for 1 hour, use 1kW-hour of electrical energy. If you look on your monthly electrical bill, youwill see how many kW-hours of electricity you used in your home. Electricalenergy costs vary significantly in different parts of the country, but for thisexample we will use a value of 8 cents per kW-hour. If you used 500 kW-hourshours and were charged 8 cents per kW-hour, your monthly bill would be $40 (500kW-hours x $0.08).
Back to the light bulb example. How many 100 watt light bulbs could the Corps' 21,000 megawatts run? Well, 1 megawatt is the same as a thousand kilowatts. Remembering that 1 kW can light 10 bulbs, and that 1 megawatt is thesame as 1000 kW, you find that 1 megawatt will run 10,000 light bulbs (1000 kW x10 bulbs/kW). Since 1 megawatt can run 10,000 bulbs, 21,000 megawatts can run210 million light bulbs (21,000 x 10,000 bulbs)!

If an average value of 8 cents per kW-Hour is used, and if all of the Corps' generating units were run at full capacity for one day, the value of the electricity generated would be: (21,000 megawatts) x (1000 kW/megawatt) x($0.08/kW-Hour) x (24 hours/day) = $40,320,000.
That would be $40 million per day if all units were running at full capacity! However, all of the Corps' generating units cannot be operated 100% of the timefor a number of reasons: The need for power varies hourly, daily and seasonally. Large quantities of electric energy cannot be stored, so electricityis only generated when needed. The amount of water flowing in rivers varies, depending on the season and the weather (at times, there is insufficient water available to run all units). Maintenance needs make some units unavailable.Environmental factors often require specialized or restricted operations.
But even with all of these factors, the sale of hydroelectric power generated from units operated by the Corps of Engineers returns an amazing amount of revenue to the US Treasury each year.

The Turbine

Most hydraulic turbines consist of a shaft-mounted water-wheel or "runner" located within a water-passage which conducts water from a higher location (the reservoir upstream from a dam) to a lower one (the river below a dam). Some runners look very similar to a boat propeller, while others have more complex shapes. The turbine runner is installed in a water passage that lets water from the reservoir flow past the runner blades, which makes the turbine spin. There are several types of turbine designs. Two popular types are the Francis and the Kaplan turbine. The Francis units are normally used for mid- to high-hydraulic heads (i.e., dams from about 75' to 1000' or greater heights), while the Kaplan units are normally used for lower hydraulic head.

The Governor

Almost all hydraulic turbine/generator units turn at a constant speed. Some units operate at 600 rpm (smaller diameter units with a high-hydraulic head), others at 60 rpm or less (large diameter units with a lower-hydraulic head). The best speed for each type of turbine is set during design, and a generator is then designed that will produce 60 cycle alternating current at that speed. A device called a governor keeps each unit operating at its proper speed by a hydraulic interface that operates wicket gates (controlling water flow into the turbine). When there are load changes or disturbances in the power grid, the governors respond by increasing or decreasing power output of the generating units to meet power demands and keep the frequency of the power grid at 60 cycles. Older governors are mechanical, with a hydraulic interface to the turbine. New governors are digital, with a hydraulic interface to the turbine.

The Corps of Engineers operates and maintains 375 hydroelectric generating units.

Generator Theory

A hydraulic turbine converts the energy of flowing water into mechanical energy. A hydroelectric generator converts this mechanical energy into electricity. The operation of a generator is based on the principles discovered by Faraday. He found that when a magnet is moved past a conductor, it causes electricity to flow. In a large generator, electromagnets are made by circulating direct current through loops of wire wound around stacks of magnetic steel laminations. These are called field poles, and are mounted on the perimeter of the rotor. The rotor is attached to the turbine shaft, and rotates at a fixed speed. When the rotor turns, it causes the field poles (the electromagnets) to move past the conductors mounted in the stator. This, in turn, causes electricity to flow and a voltage to develop at the generator output terminals.

Rotational Speed

The rotational speed of the generator is usually the same as the speed of the turbine, because they are directly connected. Some plant designs incorporate a speed-increasing gearbox between the turbine and generator.  The speed of the turbine is determined by the design and hydraulic conditions. Speeds for hydrogenerators are typically in the range of 50 and 600 revolutions per minute (rpm). For a generator operating in a 60-Hz system, the rotational speed (in rpm) times the number of field poles on the rotor is always 7,200.

The Stator

The stator is a donut-shaped structure surrounding the rotor. The stator is made up of a steel frame supporting stacked steel laminations. The conductors, called the stator winding, are recessed in slots in this lamination structure. The stator winding is arranged so that when the rotor turns, the field poles pass only a fraction of an inch from it. The movement of the magnet next to the conductor causes electricity to flow in the conductor.

Stator windings of larger generators are made up of individual stator coils. Each coil is made of multiple strands of copper. In a modern insulation system, the copper is insulated with mica held in place with an epoxy or polyester resin. The individual coils are connected to each other through jumpers and then to a ring bus. The ring bus is connected to the generator leads, which in turn are connected to a power step-up transformer. Finally, the transformer is connected to electrical power grid.  Some generator designs use half-coils (bars) in lieu of full coils.

Stator Laminations

The stator core is made up of steel laminations that are assembled in a stationary steel framework. The laminations are punched, or laser-cut, from electrical grade sheet-steel, about 0.014 inch thick. A thin coat of insulating varnish is baked on each lamination to insulate it from the other laminations to reduce eddy current losses. Notches are cut into the inner radius of the lamination, so that after assembly the stacked lamination notches align to form stator slots. The laminations are stacked, one at a time and clamped in a framework to form a rigid structure. After approximately 2 inches of the core is stacked, �-inch spacers are placed to provide air ducts for cooling air circulation.

Exciter

The exciter supplies the direct current used to create the rotating magnetic field necessary for generator action. The exciter may be a rotating type that is directly connected to the generator shaft or a modern static system using solid-state devices fed from a high-voltage bus. The excitation system is equipped with a voltage regulator, which is used to vary and control the generator voltage.

General Theory

A power transformer is equipment that is used for the economical transmission of power from generating stations to transmission lines, and eventually to consumers demanding service for light, heat, and power. A transformer typically consists of two or more electrical circuits (or windings) interlinking one common magnetic circuit. Electrical energy is transferred from one winding to the others through the medium of the magnetic circuit. For efficiency of this coupling, the magnetic field is 'channeled' through a laminated steel core that links both circuits. The winding (copper conductors) that receives energy is called the primary, and the winding that delivers energy is called the secondary. In a transformer, either winding may be the primary, depending upon that winding receives the energy. A transformer may receive energy at one voltage and deliver it at a higher voltage, in that case it is called a step-up transformer, or it may receive energy at one voltage and deliver it at a lower voltage, in that case it is called a step-down transformer. At the Corps of Engineers' powerhouses, step-up transformers are used to transfer electrical energy from the generators to the transmission lines. More detailed construction information has been provided below.

Power vs. Distribution Transformers

Commercial transformers are classified as Distribution and Power transformers. By definition, a distribution transformer is any transformer having a rating between 3 and 500 kVA, and a power transformer is any transformer having a rating above 500 kVA. Distribution transformers are used for receiving power from the transmission lines, and delivering it to the consumer at a lower voltage. Distribution transformers are built in standard ratings, that allow the manufacture of these transformers on a production basis, and permits holding them in stock resulting in lower costs and quicker deliveries when needed. Power transformers are used at powerplants and primary transmission lines for the transformation of relatively large amounts of power. Power transformers are built according to specifications to fit each application.

Transformer Construction

Core vs. Shell Form Construction

Power transformers are divided into two general types - the Core form and the Shell form. These two types differ in the arrangement of the iron core and copper windings. The photographs shown on this page are of a single-phase core form transformer constructed in 1995.

Core Form Transformer

In the core form transformer, the copper winding 'surrounds' the iron core. The core is in the form of a hollow square made up of sheet-steel laminations approximately 11 mils in thickness. The core is built up with rectangular laminations, the joints of that butt in the individual layers. Each 'leg' of the core is surrounded by both the primary and secondary windings, the low-voltage winding typically adjacent to the iron core, and the high-voltage winding typically surrounding the low-voltage winding. The core form transformer is suitable for high-voltage operation (especially at lower ratings), due to its good internal insulation properties.

Shell Form Transformer

In the shell form transformer, the iron core 'surrounds' the copper windings and is in the form of a 'figure 8'. The coils are made in the shape of pancakes, wound with strips of copper. These coils are taped, and the primary and secondary windings are stacked so that each primary is adjacent to a secondary. The secondary windings are adjacent to the iron core in order to minimize the amount of high-voltage insulation required. Shell form transformers have good mechanical design characteristics in that the tank, core, and windings are built as an integral unit, having a good mechanical strength. They also have good short-circuit strength characteristics. In general, shell form transformers are used for the larger generator step-up applications, where large currents are being handled.

Laminated Steel Core

Transformer steel cores are typically manufactured from sheet-steel punchings (laminations), that are assembled in layers (or stacked). The thickness of the laminations is determined by the required mechanical strength. allowable losses, and other manufacturing considerations, the usual range of thickness being between .007 and .011 inches. Since it is desirable to use continuous, form-wound coils, the core laminations must be assembled so that windings can be 'placed' around the core legs. Because of this, the cores are assembled with joint areas. The laminations forming each layer are typically hand assembled, and are laid as close to each other as possible at the joint area, but this 'butt' joint results in a small air-gap in the magnetic path. In order to improve the electrical characteristics of the core, the laminations are designed so that the butt joints are staggered in adjacent layers. Staggering of these laminations also makes the final core assembly stronger at the joint areas. For a shell form transformer construction, the coil assembly is first made, and then the steel laminated core is assembled around the coil assembly.

Windings

Power transformer windings are manufactured from copper, and are form-wound using a winding machine. Each conductor of the windings is individually insulated using a cellulose-based tape (typical); the amount of insulation depending upon the voltage level and internal design of the transformer. After the coils have been wound, they are 'formed' to the correct dimensions and placed in a special vacuum tank where the air is removed from the cellulose material, and heated to remove the moisture. The windings are then doused with a liquid impregnating varnish to insure that air and moisture are not reintroduced into the winding insulation, and baked in ovens to further cure the windings. After the coils have been cured, they are placed around the core lamination assembly. The coils and core of power transformers are immersed in oil, that has a better dielectric strength than air. Windings are designed such that as much surface area as possible is exposed to the insulating oil, so that the heat generated during operation is dissipated. Oil passageways must be provided so that the oil may flow past the windings. The coil and core assembly is rigidly clamped or bolted together so that there can be no shifting between parts when being handled and moved, or during operation.

Many of the USACE powerplants have been in operation for over 50 years. The cumulative effects of age and operating cycles are showing up as a pattern ofmajor breakdowns that indicates declining reliability. Engineering analysisshows that even with increased maintenance, these problems can be expected tocontinue and cause generating unit outages to increase. Increased outages causeincreased operation and maintenance costs, and increased production costs forthe power system.

The component of electrical equipment most prone to deterioration over timein service is the winding insulation system. The winding insulation is exposedto many aging mechanisms, which shorten its life, including electrical andmechanical stresses during normal operation. Other components of the windingsystem used to contain the windings within the stator laminations can also losestrength and elasticity when exposed to these stresses, eventually resulting inunwanted winding movement and eventual failure. It is not uncommon to exceed200,000 hours of generator operation before winding failures begin.

When the stator winding insulation fails, the high voltage generated in thecoils arcs to the surrounding framework, and protective relaying shuts down thegenerating unit. The unit must be repaired before it can be restarted. Differenttypes of repairs are possible depending upon the age and condition of thegenerating unit.  If damage is limited to one or two coils, the repair usuallyconsists of removing the damaged coils from the circuit by jumpering aroundthese coils. More extensive failures require partial or complete stator windingreplacement. Stator winding failures usually damage the stator core. Rotordamage is also common.   Replacing deteriorating stator windings on a planned schedule allows thedesign and manufacturing phases to be performed while the unit is still inservice. This minimizes the impact on unit availability. If rewinding is performed in conjunction with turbine repairs, some of the unit disassembly andreassembly expenses can be shared between the activities. Reliability andeconomic analysis of each winding ensures that they have reached the point atwhich a rewind is the best action. Planned, scheduled rewinds will generallyprovide the most cost-effective means to maintain the reliability of oldgenerators.

The above photo shows Hartwell Dam generator unit #5 during construction.