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

Chuck Weber - WaterOneSimon Bunn – Derceto Inc

1950’s – 1970’s Control room

PLC and RTU provide local control

1970’s : Mixed auto/manual systems

1980’s : SCADA systems appear

1990’s :Historical Databases arrive

1990-2000 Smart Instruments arrive

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. WaterOne’s current treatment capacity is 180 millions gallons

per day. 

Modern UCOS Scada System

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

What next after Scada?

Decision Support Systems

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 country’s 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.

What to optimize?

Electricity Use by WaterOne

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 speedometerkWh is the distance measured by the odometer

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

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”

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

Operator Panel

Optimizer

Operations Simulator

PC onLAN

Application Manager

PC on LAN

Key Energy Management Modules

Primary Database

Backup Database

Aquadapt Primary Database

(Live Server)

AquadaptBack-up Database (Historical Server)

DashboardPC onLAN

Data Cleaner

SCADA InterfaceOPC

Current day / real-time

WaterOne UCOS SCADA System

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

Peak Demand ReductionsMax Peak-Time kW (May 2006)

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Woodson Inflow Valve out of Service

Out of Derceto Control

Even after a major Pipe-break

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

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

Questions?