Water Distribution Optimization: Taking SCADA One Step Forward: A Case Study

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Water Distribution Optimization Taking SCADA One
Step Forward A Case Study
Chuck Weber - WaterOne Simon Bunn Derceto Inc
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1950s 1970s Control room
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PLC and RTU provide local control
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1970s Mixed auto/manual systems
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1980s SCADA systems appear
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1990s Historical Databases arrive
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1990-2000 Smart Instruments arrive
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• WaterOne is a quasi-municipal agency that
  provides water to more than 400,000 individuals
• WaterOne serves residential and commercial
  accounts in 16 cities in the Johnson County area.
  WaterOne serves approximately 135,000 customers.
• WaterOne has nearly 3,000 miles of transmission
  and distribution mains, equal to the distance
  from Kansas City to Seattle.
• WaterOne's service area covers more than 270
  square miles.
• WaterOnes current treatment capacity is 180
  millions gallons per day. 

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Modern UCOS Scada System

• Single control room for treatment and
  distribution
• Installed in 1991, upgraded 2006

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What next after Scada?
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Decision Support Systems
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What to optimize?

• Energy cost minimization is a good target, as it
  is one of the highest costs in producing the
  next gallon of water.
• "The more than 60,000 water systems and 15,000
  wastewater systems in the United States are among
  the countrys largest energy consumers, using
  about 75 billion kWh/yr nationally 3 percent of
  annual U.S. electricity consumption."Electric
  Power Research Institute, Energy Audit Manual
  for Water/Wastewater Facilities, (Palo Alto
  1999), Executive Summary.

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Electricity Use by WaterOne
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Energy and Demand Charges

• Pricing is based on two components, energy use in
  kWh and demand in kW

• Car Analogy for kWh and kW
• kW is like the speed that is measured by a
  speedometer
• kWh is the distance measured by the odometer

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Electricity Supply tariffs

• Kansas City Power Light (KCPL)
• Flat kWh tariff applies 24 hours day, 365 days
  year
• Flat demand charge, 24 hours a day, 365 days year
• Kansas City Board of Public Utilities (KCBPU)
• Flat kWh tariff applies 24 hours day, 365 days
  year
• Demand charge only applies 10 hours/weekday with
  monthly peak and 70 of highest summer peak
  setting winter charge (effectively a 12 month
  ratchet clause)
• Almost no incentive at all for shifting
  electrical load
• No options for time-of-use or real-time pricing
• Last KCPL tariff structure changes were made10
  years ago
• Market is unlikely to change or deregulate in the
  mid term

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Solving the energy equations

• Numerically impossible to solve, but the
  following techniques have been attempted
• Localized optimization at each pump station using
  profiling or time triggers
• Expert Systems using cascading rules
• Advanced techniques using Genetic Algorithms
• Multi-Objective Polynomial Systems (MOPS)
• Dynamic Programming with Stochastic analysis
• All still make considerable assumptions and do
  not achieve optimality
• A 2001 AWWA report said the market is waiting
  for an off-the-shelf solution

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A New Customized-Off-The-Shelf tool

• Over the last 4 years, Derceto Aquadapt has
  implemented energy cost optimization systems with
  leading US water utilities
• Five key cost reduction techniques were employed
• Electrical load shifting in time, to maximize
  utilisation of low cost kWh tariff blocks
  (time-of-use tariffs)
• Peak electricity kW demand reduction
• Energy efficiency improvements from pumps and
  pumping plants.
• Utilization of lowest production and chemical
  cost sources of water.
• Utilization of shortest path between source and
  destination
• WaterOne benefited primarily from peak demand
  reduction and lowest cost source selection

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Key Energy Management Modules
WaterOne UCOS SCADA System
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Project Timeline

• Feasibility Study - June 2004 to August 2004
• Detailed Design - September 2004 to April 2005
• Configuration and Testing - July 2005 to Mar 2006
• Delivery, Implementation and Site Testing -
  April/May 2006
• Had to be ready in time for peak summer demand
  otherwise majority of savings would be lost for
  2006/07
• WaterOne created and maintained an audit tool to
  measure savings on a monthly basis. This is a
  sophisticated analysis tool
• Uses formulation of kW versus MGD from four
  previous years
• Created non-linear functions to calculate kW at
  each major point
• Allowed for changes in tariff in future years to
  be incorporated
• Maintenance, Enhancement and Support contract
  started in June 2006 with latest Aquadapt version
  5.5 rolled out in 2008

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Peak Demand Reductions
5 MW Reduction
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Even after a major Pipe-break
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Results to date Electricity savings

• First month of operation May 2006, saved 90,000
• First year of operation May 06 to April 07 saved
  565,000
• First six months of 2007/08 saved 553,000
• Total of 1,118,000 saved in 18 months of
  operation
• Reduced greenhouse gas emissions by 4800
  tons/year
• Other impacts
• Has required changes in operation, but no
  additional hardware or instrumentation was
  required
• Operators were involved all the way through the
  process and had valid concerns which needed to be
  addressed
• Ongoing program of training and product
  enhancement is helping culture change and
  acceptance
• Aquadapt is now being used to identify areas
  where further savings can be made

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Conclusions

• The considerable investment in a Scada system is
  often hard to justify financially, but it is an
  essential tool
• Utilization of the data and interfaces presented
  by a Scada system in areas such as planning and
  operations optimization can provide additional
  financial benefits
• Even in an energy market that looked unfriendly
  to energy optimization, significant benefits were
  achieved
• Buying advanced software off-the-shelf reduces
  risk
• Use robust systems to measure the benefits to
  avoid doubt
• Operators need to be involved from start to
  finish, they know the treatment and distribution
  systems best
• This is just one step in the path to operations
  optimization, keep an eye on costs and benefits
  in all areas to best serve your customers

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Questions?