Hoover Dam Hydropower and River Operations Electric Market Forecasting Conference Mark Cook, PE Manager, Hoover Dam
Hoover Dam Type of Operation Impacts of Drought Mitigating Drought Impacts through Major Modifications and Improvements
Peaking Plant 17 Main Generating Units 2 Station Service Units 2074 MW Nameplate Rating Releases 9.6 Million Acre feet per year Generates about 3.5 Terawatt hours per year
4 1928 Boulder Canyon Project Act Authorizes [t]hat the dam and reservoir provided for by section 1 hereof shall be used: First, for river regulation, improvement of navigation, and flood control; second, for irrigation and domestic uses and satisfaction of present perfected rights in pursuance of Article VIII of said Colorado River compact; and third, for power.
Operation of Lake Mead and Hoover Dam Two modes of operation govern the releases from Lake Mead Flood Control (releases in excess to downstream water delivery requests) Meet the downstream water delivery requests Flood Control operations governed by U.S. Corps of Engineers regulations 5
Operation of Hoover Dam Monthly energy targets are disaggregated into each contractor s share by Western Each contractor schedules its energy to meet energy demands on a real-time basis Monthly gross energy target is met within ± 2 percent Reclamation may change monthly gross energy target within the month based on system conditions 6
Hoover s Versatility Black Start Capability Ramping Full Range Up or Down Spinning Reserve - Motoring Non-Spinning Reserve Quick Startups 7
LOAD RANGE(MW) Typical Hoover Hours of Operation 1600-1700 1500-1600 1400-1500 1300-1400 1200-1300 1100-1200 1000-1100 900-1000 800-900 700-800 600-700 500-600 400-500 300-400 200-300 100-200 0-100 1 4 21 54 97 153 246 367 510 550 644 723 814 916 1014 1211 1421 0 200 400 600 800 1000 1200 1400 1600 HOURS OF OPERATION
CAPACITY RANGE Typical Capacity Hours of Operation 1700-1800 130 1600-1700 143 1500-1600 181 1400-1500 249 1300-1400 411 1200-1300 552 1100-1200 650 1000-1100 772 900-1000 769 800-900 797 700-800 1,196 600-700 1,779 500-600 940 400-500 192 300-400 0 200-300 0 0 200 400 600 800 1000 1200 1400 1600 1800 2000 HOURS OF OPERATION
Energy Allocations Arizona, 20% California, 55% Nevada, 25%
Impacts of Drought The worst drought on record since the early 1900s reduced the generating capacity of Hoover from 2074 MW (lake elevation 1165) to presently 1576 MW (lake elevation 1082).
Constraint Expectation 1050 ft All units will have decreased power capability and efficiency 11.5 units can operate, but we expect little to no regulation ability at the high efficiency top end With low tail water submersions, cavitation damage will occur when operated above the rough zone 4.5 units will have regulation ability, but will have minimal rough zones Estimated Plant Capacity: 1371 MW
Constraint Expectation- 1000 ft All units will have decreased power capability and efficiency 11.5 units can operate, with minimal operational regulation below the rough zones Cavitation damage is expected at high loads all tail water elevations 4.5 units will have regulation ability at the top end, but with larger rough zones Estimated Plant Capacity: 1046 MW
Constraint Expectations 950 ft All units will have decreased power capability and efficiency 11.5 units may be able to run, but with cavitation or vibration damage at any load 4.5 units will have minimal regulation ability at the top end due to rough zones increasing and capacity decreasing With low tail water submersions, none of the units will be operated at full load Estimated Plant Capacity: 696 MW
Impacts of Lower Lake Elevations Loss of Total Generation Capacity Loss of Ability to Regulate Decreased Energy Output Increased Rough Zones Increased Maintenance (cavitation) Concerns
Mitigating Low Lake Elevations Efficiency and Capacity Improvements Unit Controls Modernization Major Overhauls of Turbine Components Stainless Steel Wicket Gates Opening Existing Wicket Gates beyond 100% Wide Head Range Turbine
Old Control and Relay Panels Relays for unit control, solid state relay protection, analog meters, pistol grip manual controls, and window type annunciator for alarms
New Control and Relay Panels TMC TPC GPC UCC DCDC Programmable logic controller for unit control, digital relay protection, touch screen for manual control, monitoring, and alarms
UCM Project Performance Benefits UCM improves efficiency while units are providing regulation for the power system. Faster operating mode transitions such as starting and stopping a unit Faster changing from condense mode to generate mode Faster transition/loading through the unit rough zones Faster load-following response.
Wide Head Turbines 5 Turbines Total 4 Full Size 1 Half Size
Wide Head Range Turbine Benefits Improved efficiency and wider regulating capability during low head operation Improved regulating capability, by reducing or eliminating the load ranges which produce rough zones Provides capability for capacity and regulation from Hoover at low lake levels, mitigating the risk of losing capacity, regulation, and unit availability, due to rough unit operation
Wide Head Range Turbine Design Concepts Operate at higher efficiency and increased capacity, over an effective head range of 350 feet (Lake Mead elev. 1004) to 575 feet (Lake Mead elev. 1229) Designed to operate over the entire effective head range, the best operation will be across the expected head range, from net head 396 (Lake Mead elevation 1050) to 511 feet (Lake Mead elev. 1165).
Unit Efficiency (%) 100 Unit A8 Unit Efficiency History 90 80 70 60 50 40 30 Pre-Overhaul Performance Testing Post-Overhaul Performance Testing New Runner Priliminary Performance Testing 20 10 0 0 5 10 15 20 25 30 35 40 45 50 Unit Power (MW)
A1 Turbine Installation
Wicket Gate Stainless Steel Replacement Wicket gates at Hoover Dam have extensive cavitation and erosion damage. There is also damage and wear to the bearing areas. Prior repairs (to the nose and tail of the gates) have created differences in flow patterns across the gates. An economic benefit/cost ratio and payback period for replacing the wicket gates versus refurbishing the wicket gates was conducted along with a computational fluid dynamics (CFD) analysis.
Wicket Gate Stainless Steel Replacement Condition of old wicket gates
Wicket Gate Stainless Steel Replacement Benefits from installing new stainless steel wicket gates Increasing Efficiencies with Better Flow Profiles Increasing Power Output Capacities by Allowing More Water to Pass Through Gates Avoiding Costs Due to Water Leakage when Units are shut down Avoiding Higher Condensing Costs Which Result from Water Leakage During Condense Mode
Wicket Gate Stainless Steel Replacement New Stainless Wicket Gates
Stainless Steel Wicket Gates and Widehead Turbine
Overall Results Faster Response Better Alarming More Spinning Reserve Capacity Higher Efficiency Better Reliability
Capacity in Megawatts Lake Mead Elevation Hoover Capacity with and without Wicket Gate Modifications 2100 2080 2060 2040 2020 2000 1980 1960 1940 1920 1900 1880 1860 1840 1820 1800 1780 1760 1740 1720 1700 1680 1660 1640 1620 1600 1580 1560 1540 1520 1500 As of 2016 The Total Increased Capacity = 105 MW Jun-98 Sep-02 Feb-05 Jun-06 Jul-07 Apr-08 Apr-09 Feb-10 Jan-11 May-11 Aug-11 Nov-11 Dec-11 Date 1210 1190 1170 1150 1130 1110 1090 1070 1050 1030 1010 Capacity with Wicket Gate Changes Capacity without Wicket Gate Changes Lake Mead Elevation
10 Year Annual Hoover Plant Efficiency 88% 87.5% 87.3% 87.1% 87.0% 87% 86% 85% 84% 83.3% 83.5% 84.1% 84.5% 84.7% 83% 82.6% 82% 81% 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
QUESTIONS?