Waterpower XV: Advancing Technology for Sustainable Energy

The Waterpower XV conference and exhibition convenes in Chattanooga, Tenn., this July. This event features multiple opportunities to learn about new technologies, approaches, and products and services being used to improve hydro. Here is a sampling of the information that awaits attendees.

The Waterpower XV conference and exhibition is July 23-27, 2007, in Chattanooga, Tenn. The theme is “Advancing Technology for Sustainable Energy.” A focus of the conference’s program and exhibition is new technologies and innovations.

The biennial Waterpower conference is regarded as the hydro industry’s premier technical forum. Technical paper presentations, the traditional backbone of the conference, are supplemented by “mini-conference” symposia, roundtable discussions, and special-interest poster galleries. Delegates may earn 13 hours of professional development credits.

In addition to the conference program, several meetings, workshops, technical plant tours, and the Hydro Training Institute’s “Hydro Basics” course coincide with Waterpower XV.

The Waterpower Exhibit opens the evening of July 24. A total of 238 companies will share their technology and service innovations during the three-day conference. A complete list of exhibitors is available at: www.hcipub.com/wp.

For a sampling of the kinds of best practices and innovations you’ll see at the Waterpower XV conference, this article features application of seven of the many products, services, techniques, and methods that will be on display in the exhibit hall:

— Acoustic system to monitor fish

— Flow meter systems

— Controllers and I/O systems

— Software for optimizing unit operations

— Numerical modeling of spillway flow

— Gates for diversion tunnels

— FusegateTM technology

Acoustic equipment monitors fish movement at tidal project

Verdant Power, a developer of kinetic hydropower technologies and projects, is deploying six tidal Kinetic Hydropower System (KHPS) turbines in the East River off the shore of Roosevelt Island near New York City.

The turbines will generate power from tidal currents flowing in both directions in the river. Each turbine has a 5-meter-diameter rotor and a capacity of 35 kW.

The first test turbine was deployed in the river December 12, 2006, and operated continuously until January 21, 2007 (155 tides). During that period, the unit averaged 14.5 kW of output during tides and an average energy production of 270 kilowatt-hours per day. Electricity generated was provided to nearby Gristede’s Supermarket. “Initially, we expected the unit to generate electricity 50 percent of the time,” says Aaron Hernandez of Verdant Power. “But the unit ultimately generated power to the grid 77 percent of the time.”

All six turbines are expected to be in place in 2007.

“The Roosevelt Island Tidal Energy (RITE) project will be the first of its kind in the world,” Hernandez said. “As such, there is no information from existing projects on which to base an assessment of environmental effects.” To assess potential environmental effects, Verdant Power is conducting an 18-month study of fish detection and quantity, underwater noise, hydrodynamics, and birds in the study area.

Part of the study involves monitoring animal abundance and activity in the vicinity of the turbines. To monitor fish movement and behavior, Verdant Power installed underwater acoustic equipment supplied by BioSonics, Inc. of Seattle, Wash. The acoustic monitoring systems consist of four DT-X Digital Scientific Echosounders controlling 12 underwater split-beam transducers.

BioSonics will exhibit at the Waterpower conference; at the booth, the company will provide details of its acoustic monitoring equipment systems.

“We selected an acoustic monitoring system because it is non-selective, non-invasive, not labor intensive, able to measure fish abundance over long time periods, and able to be used in the strong currents that are typical of the study site,” Hernandez says. Each monitoring system consists of one digital scientific echosounder and three split-beam transducers. The transducer arrays are mounted near the shore, with associated echosounders and other equipment housed in a facility on site. The systems are permanently connected to the Internet to allow automated operation and remote access, both by an on-site team consisting of Verdant employees and representatives of environmental consultant Devine Tarbell & Associates and by BioSonics personnel in Seattle.

The first two acoustic systems, which began operation in November 2006, are deployed immediately upcurrent and immediately downcurrent from the turbines. They form an “acoustic curtain” from the surface of the river to the bottom and across the entire width of the river in front of the turbines. The third and fourth systems are deployed outside of the immediate influence of the turbines, one upcurrent and the other downcurrent. These four systems form two acoustic curtains on each side of the turbines.

BioSonics Inc. supplied state-of-the-art acoustic equipment to Verdant Power’s Roosevelt Island Tidal Energy project. The equipment has been deployed into the East River to monitor fish.
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The outer systems detect animals approaching the turbines, while the inner systems detect those same animals passing through or around the turbines. The split-beam feature of the transducers allows classification of individual targets based on their location in the river, acoustic properties, swimming speed, and other characteristics. The coordinated network of the four systems allows for monitoring of animal movement and behavior both approaching and leaving the area of the turbines.

Each transducer is mounted on a gimbal inside a rugged housing; each set of three transducers is mounted on a large steel frame. The transducers are staggered on the steel frame in order to sample a cross-section of the river’s depth. The frames are then deployed and placed on a steep slope underwater so that each transducer sits at a particular height in the water column. Once set in place, the transducers can be aimed, using cables from the shore, at particular points upriver and downriver relative to each pair of turbines.

The AQFlow Advantage system, a portable acoustic scintillation flow meter, is mounted on the blue frame. This frame was placed in the gate slot of Unit 1 at the Kembs hydro plant in eastern France to measure flow prior to turbine refurbishment. The data is being used to set a baseline for unit performance.
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To evaluate the acoustic echo signals received by each system, BioSonics developed a complex acoustic data system, which uses “trained” signal processing and pattern recognition software. The hardware and software can measure and test a variety of conditions against threshold values established by team scientists and regulatory agencies. If the system detects animals in the vicinity of the turbines and those detections meet the threshold criteria, the system alerts project personnel. Personnel can then review and evaluate recorded acoustic data. The system continuously evaluates and summarizes the acoustic data and publishes hourly reports of activity, results, and alerts issued.

The 12-transducer array has been augmented with a DIDSON (Dual-Frequency Identification Sonar) transducer, supplied by Sound Metrics Corporation of Lake Forest Park, Wash. This transducer includes an array of sensors that provide a real-time video-like image. “Our analysts log every event they see with the DIDSON,” Hernandez says. “Events may include one fish, two fish, a school, etc. And with each event, they note parameters such as date, time, tidal cycle and distance from shore.”

Since the acoustic system began operating November 6, 2006, there are no recorded events of fish strikes. Fish are observed predominantly near the riprap. The smallest fish visible to date at the farthest range (15 to 35 meters) was about 0.15-meter-long; the largest fish observed to date was 1.95 meters long at 17.5 meters from the DIDSON.

According to Verdant Power, both the BioSonics split-beam systems and the DIDSON unit are working as expected.

Owing to successful installation and monitoring results, Verdant contracted with BioSonics to install a complete second set of systems (bringing the total to eight echosounders and 24 transducers) in preparation for the installation of four more turbines at the site.

New flow meter system provides data for turbine rehab

In rehabilitating Unit 1 at its 150-MW Kembs hydroelectric station, plant owner Electricité de France (EdF) needed to precisely measure the amount of flow passing through the unit. To do this, EdF purchased a portable acoustic scintillation flow meter (ASFM) Advantage System from ASL AQFlow, Inc. EdF will use the flow meter to obtain baseline flow measurements. These measurements will be useful for during rehabilitation and in subsequent plant operations.

ASL AQFlow, a provider of acoustic flow meters in Sidney, British Columbia, Canada, will be in the exhibit hall to share details about its products.

The Kembs plant, on the Rhine River in eastern France, began operation in 1932. EdF recently launched a major refurbishment to increase the plant’s efficiency and power output. The work includes replacing the Unit 1 Kaplan-type turbine with a new five-blade runner supplied by VA Tech Hydro Andritz. With the new runner, scheduled for commissioning in 2007, EdF expects a 4 percent increase in power output.

Marie Delagarde, a hydraulic engineer with EdF, says the utility chose the AQFlow system because of the site characteristics of the Kembs project — low head with short intakes.

“ASL AQFlow specializes in flow measurements at low-head, short-intake hydro plants, which present among the most difficult flow measurement challenges,” says Colleen McQuade, marketing coordinator at ASL AQFlow.

The head at the Kembs plant is 13.5 meters. The plant has six 24.8-MW units — two with Kaplan runners and four with fixed-blade propeller runners. Water is directed to each unit through four 17-meter-long intake bays.

“A simple way to measure flow in these conditions is with the ASFM mounted on a frame and lowered down the stoplog slot just downstream of the trashrack,” says Jan Buermans, sales engineer with ASL AQFlow. “The turbine can stay in service and does not need to be dewatered for flow meter installation.”

The flow meter system EdF leased for measuring flow at the Kembs plant includes two innovations. One is an improved algorithm when compared to other AQ Flow products. The improvements are a result of AQFlow’s continuing study of factors affecting ASFM performance. As a result of these studies, the guidelines determining the suitability of an intake for ASFM operation have been revised and clarified.

“These studies have resulted in a new version of the instrument’s flow algorithm, with improved performance in regions of strong turbulence and unsteady flows,” McQuade says. “While Kembs has no strong turbulence or unsteady flows, Unit 1 does have skewed flow because it is located nearest the western riverbank.”

The second innovation of the flow meter system EdF is using at Kembs allows ASFM operation over a greater range of path lengths.

Before purchasing the Advantage ASFM, EdF leased a two-bay, two-paths-per-bay ASFM Advantage system and installed it at Kembs in June 2006 for a one-week test. The purpose was to establish performance of Unit 1 and to determine suitability of the ASFM. “The system worked well for determining relative flow,” Delagarde says.

The SoftPLC Tealware I/O, a rack-mounted, high-density distributed system that brings signals into the controller, has been in operation at the John Day Dam project in Oregon since 2002.
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The ASFM had four acoustic paths — two mounted on each of the two open frames fitted into the stoplog slots. Operators collected data at 13 frame positions in the intake, with data from two bays collected at one time. They then moved the frames to the remaining two bays.

This first set of flow measurements set a baseline for unit performance. Once the refurbishment work is completed, a second set of flow measurements will establish the improvement in performance.

Putting control systems to work at Corps projects

To remotely control equipment used for power generation, spill, fish passage, and other auxiliary systems at its hydro projects, the U.S. Army Corps of Engineers uses controllers manufactured by SoftPLC Corporation.

SoftPLC, headquartered in Spicewood, Texas, is exhibiting at the Waterpower conference.

The Corps began installing SoftPLC equipment in the late 1990s and continues with new installations today. 

For example, at the Corps’ 1,050-MW Bonneville hydro project in Oregon, programmable logic controllers (PLCs) from SoftPLC control the main units at both Powerhouse 1 and Powerhouse 2 as well as the spillway gates. “The Bonneville project is about 2 miles in length. It’s important for operations personnel to know what’s going on throughout the project,” says David Smith, hydroelectric power operations manager at Bonneville. “By using remote controllers that are networked with fiber, or in some cases local area network (LAN) cable, we can add various alarm points without running miles of copper cable.”

Another example is the use of SoftPLC’s Tealware I/O at the Corps’ 2,160-MW John Day project, also in Oregon. The Tealware I/O, installed in 2002, is a rack-mounted, high-density distributed system that brings signals into the controller. It can be used locally or remotely in a number of configurations, including ethernet using ModbusTCP. At John Day, the Tealware I/O is used to bring field signals into the controller for use in control of the project’s navigation lock gates.

SoftPLC controllers suit a wide variety of hydropower applications. Controller features include an embedded Web server, up to 256 megabytes of memory, and support for user-developed custom functions. Communications support most industrial networks.

“Some industrial equipment vendors create proprietary networks for communicating to their controllers or I/Os,” says Cindy Hollenbeck, spokesperson for SoftPLC. “Our SoftPLCs can communicate to these proprietary industrial networks, in addition to standard networks such as TCP/IP ethernet and serial links.”

Mighty River Power in New Zealand is installing decision support system software in an effort to improve operational efficiency of the 39 generating units in its nine hydro plants.
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At Bonneville, the Corps uses ModBus, ModbusTCP, and Allen-Bradley DF1 ethernet protocols. “Our SoftPLCs come with a LAN card installed,” Smith says. “The LAN card is generally connected to a network switch that uses fiber. Each SoftPLC has an IP address (e.g., 192.168.27.XX), and each network switch has an IP address. A database manager (iFix) queries those IP addresses for information. The database manager then interfaces with a real-world monitor to display values.”

The SoftPLC product is scaleable from small to large applications. “The same user interface and training can be used for all control needs in a facility, thus minimizing training, spare parts, software licensing, and other maintenance costs,” Hollenbeck says. “It also embeds a high-end firewall, for ensuring secure communications, even from remote locations. Most of the Corps’ applications use custom functions developed using our Programmer’s Toolkit or specialty functions available from our Internet site.”

The SoftPLC products are “open architecture,” which means they can easily be adapted to work with products from other vendors. In the Corps applications, some of these other products include I/Os from MTL and Opto22, power meters, operator interfaces, and the main control room supervisory control and data acquisition (SCADA) systems.

“Our technicians are impressed by the speed, low cost, and programming tools,” says Robert W. Ford, P.E., senior electrical engineer, who supervised the group who installed the SoftPLC at the John Day and The Dalles plants in early 1999.

During installation, Ford says, “there were, of course, several start-up issues with communications and functionality. But the SoftPLC staff members were a great help in those areas, providing and even writing new drivers for our application. The product is working well and has been proven to be very reliable.”

Software for optimizing unit operations

Mighty River Power owns and operates nine hydro plants with a total of 39 turbine-generator units on the Waikato River in New Zealand. The stations, with a total capacity of 1,040 MW, operate in a cascade; water from the upstream generating plants flows downward to the other plants.

“For some time, we have recognized that additional value could be extracted from our hydro generating units by ensuring that they are running at their most efficient point for any given station load,” says Andrew Spackman, project technical manager for Mighty River Power. “However, the many demands on the trading group dispatchers (plant operators) and the rapidly changing nature of our generation profile made this difficult to achieve with the manually-driven remote-control system we had in place. We felt that a software solution was the best option.”

For this software solution, the utility wanted a proven system that could be serviced and supported in New Zealand. The software needed to provide real-time solutions and interface seamlessly with all of the utility’s existing production systems and databases.

After a review of available options, Mighty River Power chose the RT Vista software from Synexus Global, a decision support system provider for the hydropower industry based in Niagara Falls, Ontario, Canada. During the Waterpower conference, Synexus Global will share details about its various products with exhibit hall visitors.

RT Vista is the newest module of Synexus Global’s Vista decision support system. It works continuously to ensure optimum real-time dispatch of hydro generating units in a cascade. RT Vista’s output passes directly to a plant’s supervisory control and data acquisition (SCADA) control system — either as an advisory recommendation or in a closed loop to the unit’s programmable logic controller (PLC). The operations results also pass to an archiving system to enable reporting of post audit performance standards.

The Vista suite of software also includes modules to:

— Plan long-term water management (LT Vista);

— Schedule operations on a more detailed basis over the next one to two weeks on half-hour or hourly intervals (ST Vista);

— Forecast natural inflows to each watershed (Inflow Vista); and

— Undertake strategic studies (AUTO Vista).

Hydro owners using Vista software can expect a 2 to 5 percent increase in energy production and a 3 to 10 percent increase in revenue, according to Stuart G. Bridgeman, director of Vista sales and marketing. “We often do post-audit analyses comparing historic operation to the operation possible with the decision support system,” he says. “Several of our clients have published papers that substantiate these claims.”

Mighty River Power recently completed factory acceptance testing of the RT Vista software. Site installation and testing occurred in March 2007.

“We are pleased with the progress to this point and feel that 95 percent of the product features that we have requested are working as expected,” Spackman said at the end of February. “We fully expect that the remaining 5 percent will be satisfactorily completed by the end of on-site testing. The live connection to our systems will not be fully proven until the on-site installation is complete.”

Visual comparison of 50,000 cubic feet per second of flow over Smith Mountain Dam from a 1960 physical model (left) and from a 2005 computational fluid dynamics (CFD) numerical model (right) demonstrates the accuracy and usefulness of CFD in evaluating dam performance.
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Spackman advises other hydro owners contemplating such a system to “be careful not to underestimate the effort required and the complexity involved in interfacing the separate systems and databases required to make this work successfully. That has been the most challenging part of the project.” He says Mighty River Power looks forward to the full commissioning of the RT Vista product to realize the expected efficiency gains.

Numerical modeling of spillway flow

Based on a revised probable maximum flood (PMF) study for the 586-MW Smith Mountain Dam hydroelectric pumped-storage project on the Roanoke River near Roanoke, Va., utility American Electric Power (AEP) wanted to verify the performance of the dam. At issue was whether a PMF would adversely affect spillway structures.

The 235-feet-high double arch concrete dam with a top width of 816 feet has two ungated overtopping spillways. Each spillway has a total clear opening of 100 feet and a spillway crest elevation of 795 feet. Water passing over the spillway freefalls into a catch chute. The chute, in turn, directs the water toward the river. During a PMF, computed flows of 120,000 cfs would significantly exceed the spillways’ original 50,000 cfs design capacities. The computed pond elevation would increase to 821.9 feet from 812 feet.

The main concern was that the increased flow would cause freefalling water passing over the spillway to overshoot the catch chute, resulting in scour of the bottom portion of the spillway.

AEP contacted Alden Research Laboratory, Inc., of Holden, Mass., to discuss options for evaluating spillway performance during a PMF. Forty-five years earlier, Alden had built a physical model of the original spillway prior to construction.

“We suggested using a computational fluid dynamics (CFD) simulation validated with experimental data from the 1960 physical model study to determine the trajectory of the flow at the higher PMF flows,” says Dan Gessler, Alden’s director of numeric modeling.

For the 2005 tests, Alden consultants used the CFD program, FLOW-3D®, from Flow Science, Inc. in Santa Fe, N.M., to compute the trajectory. Flow Science, Inc. is exhibiting at the Waterpower XV conference to share details of its CFD software offering.

The simulation results closely correlated to the results of the physical model study performed in 1960. The simulation showed that water trajectories at the higher flows associated with a PMF would stay within the spillway’s catch chute.

“Using the CFD software simulation saved four to six months and cost only 20 percent of the estimated cost of building and testing a physical model,” says Bernie Rasmussen, AEP principal engineer.

Gates for 800-MW Koldam in India are among world’s largest

Everything is big at the 800-MW, run-of-the river Koldam hydro project in India. The project is being built just upstream of the Bhakra Reservoir on the Satluj River in Himachal Pradesh State in the Himalayas. When completed, the rockfill dam will be one of the highest in India. The tunnels used to divert the river during construction are among the largest in Asia. The vertical-lift inlet gates for these tunnels are among the largest in the world. Additionally, gates for the spillway and draft tube will be among the largest in the world.

These gates are being supplied by Om Metals Infra Projects Ltd. of New Dehli, India. The company is exhibiting at Waterpower XV, and will share details about its various gate products.

Koldam is the first hydroelectric project for the National Thermal Power Corporation Ltd (NTPC), India’s largest and the world’s fifth largest power utility. The utility first identified the site for potential hydro development in the mid-1960s. NTPC plans to begin operation of the hydro plant in 2009, with an expected annual generation of 3,054 gigawatt-hours (GWh). Koldam will provide peaking capacity to India’s northern grid.

Two important features of construction of the 163-meter-high, rockfill dam are the two parallel 14-meter-diameter horseshoe-shaped tunnels being used to divert the river during construction. The two tunnels (900 meters long and 930 meters long, respectively) each have a discharge carrying capacity of 6,500 cubic meters per second. Each tunnel inlet is divided into two bays by a central pillar, with each bay fitted with a roller gate. The 6-meter-wide by 14-meter-high inlet gates, which were commissioned in December 2004, are made of carbon steel (IS 2062 grade).

The inlet gates for the two diversion tunnels at India’s 800-MW Koldam hydro project are 6 meters wide by 14 meters high, making them among the largest gates in the world for a diversion tunnel.
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Om Metals, under contract for all the hydromechanical equipment, designed, manufactured, supplied, installed, and commissioned inlet gates for tunnels No. 1 and 2. Gate requirements and functions are unique for each tunnel.

The gates for Tunnel No. 1 are required during construction and up until reservoir filling. When the water in the reservoir reaches the spillway crest level of Elevation 625 meters, the inlet to the tunnel will be plugged. The gates for Tunnel No. 1 are designed to withstand water load of up to 115 meters of head; they operate like a wheel gate.

Tunnel No. 2 will have a bottom outlet to control reservoir water levels during impoundment. Before filling begins, the inlet gates for Tunnel No. 2 will close to enable construction of the bottom outlet and installation of an outlet gate. Then, when filling begins, the inlet gates will be opened and the bottom outlet gates will be closed. If it becomes necessary to stop the reservoir from filling, the bottom outlet gates will be opened.

After the commissioning of the project and as soon as the water reaches elevation of 540 meters, Tunnel No. 2 will be completely filled, via a bell mouth valve. The tunnel’s outlet radial gates will be closed.

New hydrology indicated the probable maximum flood (PMF) could overtop Otter Brook Dam, a U.S. Army Corps of Engineers flood control structure in New Hampshire. The Corps retrofitted the structure with six Fusegate units to increase spillway discharge capacity.
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In addition to the gates for the two diversion tunnels for Koldam, Om Metals is providing spillway radial gates without flaps (each gate is 17.1 meters wide by 17.64 meters high), spillway radial gates with flaps (each gate is 17.1 meters wide by 17.64 meters high, with a flap of size of 14 meters wide by 3 meters high), intake gates, and draft tube gates.

Increasing discharge capacity of Otter Brook spillway

The U.S. Army Corps of Engineers’ Otter Brook Dam in Keene, N.H., is one of a network of flood control dams on tributaries of the Connecticut River. Over the years, the dam has saved an estimated $29.9 million in flood damages.

When built in 1958, the 133-foot-high earthfill dam was designed to pass storms with peak runoff of 38,000 cubic feet per second (cfs), with up to 35,000 cfs passing through the spillway. However, in 1990, the probable maximum flood (PMF) calculation was revised to 64,800 cfs. The updated hydrology meant that, under PMF conditions, water would overtop the dam crest by 1 foot, which could cause dam failure.

    The Corps had to retrofit the dam.
    But how?

Options considered included raising the dam crest, widening the spillway, or using fuse plugs. The Corps evaluated options in terms of technical viability, costs, environmental issues, archeological and historical protection, and real estate easement acquisition requirements.

Of particular environmental importance was an upland forest upstream of the dam and two wetlands in the spillway diversion channel areas located upstream and downstream of the control section. Raising the dam could threaten the forest area. The presence of the federally endangered dwarf wedge mussel in the downstream wetlands area eliminated the option of an erodible fuse plug spillway augmentation. That’s because PMF conditions could result in concentrated solids loading that would affect the mussel.

After evaluating all options, the Corps chose the Hydroplus Fusegate System. This system, from Hydroplus, Inc. of Falls Church, Va., is in use at more than 40 installations worldwide. Hydroplus is exhibiting at the Waterpower XV conference.

The Fusegate system’s concept involves gravity units resembling open buckets that act as water retaining structures. These buckets are made of pre-cast concrete with inlet wells of stainless steel. At a pre-determined reservoir elevation, water enters the buckets, tips them over, and sweeps them downstream. Each bucket’s inlet well is set at a different height, so the units tip sequentially. During a PMF event, the sequential tipping of the units increase the spillway discharge capacity and leave the spillway free to discharge the flood.

In addition to installing six Fusegates at Otter Brook Dam, the Corps:

— Removed the ogee spillway;

— Excavated the spillway channel floor both upstream and downstream of the existing weir;

— Placed a new concrete sill, pier, and abutment walls on both sides of the spillway channel (the Fusegates sit on the concrete sill);

— Reconstructed a wetland upstream of the new Fusegates; and

— Constructed a 265-foot-long dike on one side of the spillway channel to protect the downstream wetland area.

By using the Fusegate system, the Corps limited construction to the existing spillway weir and approach channel. The work was completed in 2006.

For more detailed information about all conference events and registration, visit www.hcipub.com/wp/index.asp. To request a copy of the brochure, telephone (1) 816-931-1311, ext. 129, or E-mail: waterpower@hcipub.com.

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