USCID conference on Benchmarking Irrigation System Performance Using Water Measurement and Water Balances.

----------------------- Page 1-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                    Water Measurement and Water Balances. San Luis Obispo, CA.

        http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf ITRC Paper No. P02-004



                       MODERNIZING IRRIGATION FACILITIES

            AT SUTTER MUTUAL WATER COMPANY:                             A CASE STUDY



                                          1                     2                     3

                  Frederick F. Schantz  , Stuart W. Styles  , Beau J. Freeman  ,

                                                  4                      5

                                Charles M. Burt  , Douglas Stevens



                                        ABSTRACT



In 1999 Sutter Mutual Water Company (SMWC) began an effort to modernize its

water-distribution system in an attempt to reduce operation and maintenance costs

and conserve water and power resources.  The primary technical support was

provided by professionals from the Irrigation Training and Research Center

(ITRC), California Polytechnic State University (Cal Poly), San Luis Obispo.

Additional technical expertise was provided by Concepts in Controls of Visalia,

California and Wilson Pumps of Woodland, California.              This modernization

project was partially funded by the United States Bureau of Reclamation (USBR),

Mid-Pacific Region, Northern Area Office, through a Field Services Program

Grant and technical support agreement with the ITRC.



The effort encompassed two projects within the company’s service area located

within the boundaries of California’s largest reclamation district, Reclamation

District 1500.  The projects were (1) the automation of the pumping plant at

Portuguese Bend with a new Variable Frequency Drive (VFD) pump and

Supervisory Control and Data Acquisition (SCADA) system and (2) the

demonstration of new SCADA-compatible electronic flow measurement

technologies for both canals and pipelines.



The anticipated, and ultimately realized, benefits of the modernization effort was

a savings to the company due to a reduction in the amount of water diverted,

power consumed and number of personnel required to operate and maintain its

system.



1 Operations Manager, Sutter Mutual Water Company (SMWC), P.O. Box 128, Robbins,



CA   95676.   ffschantz@aol.com

2 Director, Irrigation Training and Research Center (ITRC), California Polytechnic State



University (Cal Poly), San Luis Obispo, CA       93407.  sstyles@calpoly.edu

3 Senior Irrigation Engineer, ITRC, Cal Poly, San Luis Obispo, CA        93407.



bfreeman@calpoly.edu

4 Professor and Chairman, ITRC, Cal Poly, San Luis Obispo, CA          93407.



cburt@calpoly.edu

5 President, Concepts in Controls, 225 S. Cotta Ct. Visalia, CA      93292.



dougstevens@MSN.com



                  Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 2-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                    Water Measurement and Water Balances. San Luis Obispo, CA.

        http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf  ITRC Paper No. P02-004



                                     INTRODUCTION



Sutter-Mutual Water Company (SMWC), a farmer-owned, non-profit water

company, decided in 1998 to begin modernizing its irrigation facilities in an

attempt to reduce its increasing operation and maintenance costs while conserving

water and power resources.        The following paper is a 1999-2001 status report on

what has become an ongoing effort.



The work completed to date has been possible due to a coordinated effort between

company personnel and professional engineers from the Irrigation Training and

Research Center (ITRC), California Polytechnic State University (Cal Poly), San

Luis Obispo, Concepts in Controls, Visalia, California and Wilson Pumps,

Woodland, California.  This modernization project was partially funded by the

United States Bureau of Reclamation (USBR), Mid-Pacific Region, Northern

Area Office, through a Field Services Program Grant and technical support

agreement with the ITRC.



Background



For over 80 years the company has operated and maintained its irrigation

facilities, initially using mostly vintage technology, which has proven to be very

reliable.  In the 1960-1970s, three new pumping stations were built and more

efficient turbine pumps were installed to help reduce power consumption and to

increase water diversion efficiency.  For economic and operational reasons, in

1999 it was decided to begin installing additional technology in some of the plants

in order to take advantage of the substantial savings offered by such technology.



The first equipment chosen by the company was a Variable Frequency Drive

(VFD) unit and a Supervisory Control and Data Acquisition (SCADA) system,

which were installed in the Portuguese Bend plant during 1999-2001.  While this

project was being completed a second project was also initiated in order to

measure flows in two different canals.        Both of these projects are described

below.



Description of Company



Formed in 1919, SMWC is one of the first water companies to be established in

the state of California.  The company’s physical location (Figure 1) is

approximately 45 miles northwest of Sacramento, California and is bordered in

the north by the Tisdale Bypass, in the west by the Sacramento River and in the

east by the Sutter Bypass.  The southern boundary is located at the southern end

of Sutter County near the Fremont Weir where the Sacramento River and Feather

River come together.      The company’s 46,746 irrigable acres (18,917 ha), which

are part of the 67,850 (27,470 ha) gross service area that is maintained by

Reclamation District 1500 flood control and drainage personnel, are served by



                  Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 3-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                      Water Measurement and Water Balances. San Luis Obispo, CA.

        http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf       ITRC Paper No. P02-004



approximately 400 turnouts.           Approximately 200 miles (322 km) of canals and

laterals in the distribution system convey water to the fields.



             Figure 1.  Map of Sutter Mutual Water Company service area



                    Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 4-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                    Water Measurement and Water Balances. San Luis Obispo, CA.

        http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf  ITRC Paper No. P02-004



   PROJECT #1:         INSTALLING A VFD UNIT AND SCADA SYSTEM AT

                 THE PORTURGUESE BEND PUMPING PLANT



In early 1999 the company decided to proceed with the installation of a Variable

Frequency Drive (VFD) unit and a Supervisory Control and Data Acquisition

(SCADA) system in the pumping plant at Portuguese Bend (Figure 2) following

an explanation of the technology by ITRC staff who detailed the work to be done,

the equipment to be used and the cost and benefits of the project.            The VFD, in a

manual mode, was successfully installed by the end of the year after three unique

problems critical to the successful operation of the new technology were

identified, evaluated and resolved: (1) an adequate radio signal between the office

and field site, (2) proper siphon breaker operation, and (3) adequate cooling of the

VFD unit.  A description of the VFD and SCADA system is as follows.



The Variable Frequency Drive (VFD) Unit



Constant-speed AC motors drive many pumps used for water distribution and

delivery at the district or grower level.      When flow control is needed to

accommodate changes in downstream demand, typically two methods are

employed to control the flow rate and pressure:  (i) a downstream throttling valve

is used to alter the system curve, and (ii) some of the output is by-passed back

into the intake.



        Figure 2:    Portuguese Bend Pumping Plant on the Sacramento River



With these two methods a considerable amount of energy could be wasted in

doing work that is not needed just to achieve the desired flow rate.  VFD units



                  Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 5-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                    Water Measurement and Water Balances. San Luis Obispo, CA.

        http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf   ITRC Paper No. P02-004



provide an effective way of reducing the speed of the pump drive motor, thereby

allowing the flow rate or pressure to be adjusted to the desired level without the

additional energy from throttling or by-passing.  Basically the VFD is an

electronic device that is used in conjunction with a constant-speed AC motor.

The VFD accepts the standard line voltage and frequency then converts the signal

into a variable frequency and voltage output that allows the standard constant-

speed AC motor to be varied in speed.



Advantages of a VFD:         VFDs provide the potential for system automation of

pumping plants such as Portuguese Bend.            Water level sensors can be used as

feedback into the controller to continuously adjust the VFD speed for varying

downstream conditions.  In general, this permits the ability to provide water

deliveries to growers on-demand.         In turn, growers are able to schedule irrigations

to match the crop water requirements rather than district limitations.  This type of

VFD operation also offers the potential for labor savings over manual adjustment.

The further advantages of VFD systems include the following:



     • Softer starting: the device limits the current inrush to the motor providing

         for a smooth non-shocking acceleration of the pump shaft speed up to its

         operational RPM

     • Elimination of pressure surge: bringing the system up to operating speed

         slowly removes the pressure surge caused by an almost instantaneous

         acceleration of the water to its operational flow rate

     • Reduction of operating costs: by reducing the energy input over previous

         control methods (by-pass) operating costs can be reduced

     • Reduction of motor stress:         reduces mechanical stress on motor windings

     • Reduction of peak demand charges:  by reducing the energy loads the

         overall peak demand of the facility can be reduced



Disadvantages of a VFD:  There are important issues to consider when VFD

devices are being used, as follows:



     • Increased motor stress: electrical stress increased due to the steep voltage

         wave that forms in the power supplied by the inverter.            Older motors with

         inferior insulation may have problems.          Typically the motor should be

         dipped and baked twice.  Newer VFDs that include “soft switching output

         technology” can significantly reduce motor stress and interference from

         harmonics.

     • Increased maintenance: while VFD units are very reliable they are an

         additional item requiring maintenance.  In critical applications, it is

         essential to have spare parts and maintenance expertise or retain the ability

         to by-pass.

     • Harmonics concern: with the increasing number of control systems going

         on-line, the line interference produced by some VFD units can cause

         problems.



                  Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 6-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                        Water Measurement and Water Balances. San Luis Obispo, CA.

         http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf              ITRC Paper No. P02-004



     • Environmental conditions: most units require relatively dust free

           enclosures with some type of temperature control.  Most of the pumping

           VFD applications can utilize a simple water-to-air radiator type cooling

           system (simple and effective).



Energy Savings:  VFD units usually reduce pumping costs by reducing the pump

drive motor speed to match the desired operating conditions thereby reducing

energy input.       Without a VFD device this is typically accomplished by using

either a by-pass set-up or a downstream throttling valve.  The system layout for a

typical by-pass installation consists of a pump and by-pass piped into a standtank.

With this arrangement the by-pass maintains a constant head in the standtank

regardless of flow, as there is less downstream demand.                         The excess flow is by-

passed to the pump intake to maintain a constant head in the standtank or canal.

Determining how a pump will operate in a given situation requires an

understanding of the pump and system curve.                       The pump characteristic curve for a

standard centrifugal pump shows that the pump, at a fixed speed, has a flow rate

associated with a particular pressure; high flow, lower pressure vs. low flow,

higher pressure.  The intersection of the pump curve and the system curve shows

the point of system operation.



If, instead, the pump speed is modified using a VFD device to control head just

below the by-pass, flow and head are reduced together along the system curve.  A

comparison of the relative pump water horsepower with (i) VFD, and (ii) by-pass

installations are shown by the shaded areas in Figure 3.



   e

   r                   Reduced Speed                           e

   u                                                           r

   s                                                           u

   s                                                           s

   e                                                           s                   Reduced Speed

   r                                                           e

   P                                                           r

                                                              P

   d                                                          

   a                                                          d

   e                                                           a

   H                                                           e

                                                              H



                        Static head or Lift                                         Static head or Lift



    Flow Desired                              Flow Unthrottled Flow Desired                              Flow Unthrottled

   No By-pass                                                  No By-pass



  Figure 3.  Water horsepower (shaded area) for pumping plant with (i) VFD and

                                                  (ii) by-pass



However, the water horsepower differences above are only some of several

factors to consider.  To properly compare the actual cost savings of a VFD

system, the overall plant pumping efficiencies with and without the VFD device

also need to be considered.  The major additional losses that must also be

considered in determining the overall pumping plant efficiency are as follows:



                      Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 7-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                    Water Measurement and Water Balances. San Luis Obispo, CA.

        http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf   ITRC Paper No. P02-004



         • As the system curve changes or the pump speed is reduced, the

             operating efficiency of the pump changes.           Therefore, for each

             operating point the pump efficiency must be checked.

         • VFD units have some losses associated with the conversion process to

             the new operating frequencies.  In general the units are relatively

              efficient, 95%.    But, as the frequency is lowered, some units do

             become less efficient.      The individual specifications for the VFD being

             considered should be obtained.

         • Electric motors if sized properly near maximum loading, can be very

              efficient.  With VFD units used in pumping, the motor loading is

             reduced as the speed is reduced.        This reduction in motor loading can

             reduce its efficiency and drive motor losses will result.

         • Drive friction losses can be reduced with VFD applications.  As the

              speed is reduced the mechanical friction on drive shaft components is

             reduced.



In addition to the items above, it is important to consider the relative volume

pumped each season.        Small pumping volumes generally produce small savings

and do not justify VFD installations.



Cost Savings Analysis:  To determine the total savings due to the VFD unit, a

detailed cost savings analysis was begun on the VFD installation on pump #1

(100 hp motor) at the Portuguese Bend pumping plant.  Initial savings have

already been realized with the reduction of one employee who was needed to

constantly monitor and reset the plant’s three pumps as dictated by flow

requirements out of the plant’s main canal.  The main costs now under evaluation

involve two other components as follows:            (1) energy savings as a result of

eliminating the by-pass practice (before meter) to control delivery flow, and (2)

reduction of spilled water out of the canal, which reduces metered pumping of a

purchased volume, plus the additional energy savings associated with the

reduction in pumped volume.  Both portions of the savings analysis do not take

into consideration the specific time of use rates; they are based on the total

monthly values.  The reduction in canal spill and the associated energy savings

are only achievable with the new SCADA system.



Table 1 shows the expected estimated annual energy savings based on the reduced

pumping costs associated with a VFD unit.  The cost savings analysis is based on

an estimate of the average pumping costs before and after the installation of a

VFD unit.     In addition, an estimate of the average pumping cost with a VFD using

a simple control algorithm is included to illustrate the expected additional cost

savings during the first year operating with the new SCADA system.                 Table 2

shows the anticipated annual savings of approximately $2,000 to the company on

Portuguese Bend’s main canal due to the reduction in spilled water along the

canal.   Total cost savings from reducing both canal spill and from overall energy



                  Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 8-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                    Water Measurement and Water Balances. San Luis Obispo, CA.

        http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf ITRC Paper No. P02-004



cost savings should be between $14,000 and $18,000 per year and will increase

even more in the future as energy costs continue to increase.



      Table 1.   Average annual energy savings expected from VFD operations



                             Pumping           Annual Energy            Annual Energy

                                Cost          Savings based on         Savings based on

           Item                 $/AF          6,000 AF/ Season        8,000 AF/ Season

      without VFD                4.7                  ---                      ---

        with VFD                 3.0               $10,200                  $13,600

     with VFD and

                                 2.7               $12,100                  $16,200

    simple algorithm



Table 2.   Average annual savings anticipated from a reduction in Portuguese Bend

                  canal spill with the new VFD and SCADA system



                                 Description                                  Amount



    Approximate annual spill at end of canal (acre-feet)                         200

    Possible reduction in spill with VFD (acre-feet)                             120

    Water value as missed opportunity to sell ($/acre-feet)                    $12.00

    Possible revenue from missed sales annually ($)                            $1,440

    Approximate pumping cost $/acre-feet (from pump test data)                  $4.18

    Energy savings from reduced pumped volume ($)                               $502



                                Total Anticipated Canal Spill Savings          $1,942



The SCADA System



Overview:  The basic objective of the automation at Portuguese Bend was to vary

the pump flow rates from the pumping plant in order to maintain a target water

level in the canal.  This required the integration of a VFD unit at the pumping

plant and a new SCADA system.  Specifically, this involved the ability to

remotely monitor the system (water levels, flow rates, pumps on/off, etc.),

manually control operations from SMWC’s administration office, and to

eventually control the system automatically using the new VFD unit.  This

required the integration of data acquisition components (sensors for water level,

electronic flow meters, etc.) with computerized controllers for implementing

supervised commands.        Monitoring and controlling operations at a remote site

such as Portuguese Bend further required a two-way communications network



                  Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 9-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                     Water Measurement and Water Balances. San Luis Obispo, CA.

        http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf   ITRC Paper No. P02-004



between the remote office location and the control site.  Such a system is often

referred to as a Supervisory Control and Data Acquisition (SCADA) system.



SCADA is a tool that allows irrigation companies or districts to acquire real-time

information and control operations at remote sites from a central location, usually

in the main office or at an operations center.         By having this real-time information

available at the office, the system can also be managed on a real-time basis,

thereby providing the ability to achieve maximum water conservation and

operational flexibility.



In the water industry, the SCADA systems installed just a few years ago were

one-of-a-kind systems custom designed for a specific job.              As a result, these

systems were not in most cases industrially hardened.  Their relatively short-term

design efforts did not address all of the day-to-day conditions the components

would be subjected to.  Consequently, system reliability was low.  In addition, the

communications protocols were all unique within these proprietary systems;

therefore, no interchangeability between components and different vendors was

possible.   The overall communication systems used also added to the unreliability

of early SCADA systems.          The older systems typically used lower frequency

voice radios for data transmission that were prone to many outside disturbances.



Current SCADA systems are now being designed under a term called “open

architecture”.    This new approach uses off-the-shelf industrially hardened

components, which can be linked together using common communication

protocols.  One such protocol currently adopted by the industry is Modbus.  The

current systems configuration assembles individual components, called Remote

Terminal Units (RTU’s), to control or monitor at each site independently.  These

standard components are then configured (programmed) for the specific task.  The

site RTU information is then linked back to the central location via radio

communication.       The open architecture and industrially hardened components

have allowed increased scalability and reliability.



Radio communication for the SCADA systems has also improved.                     Equipment

and FCC regulations have allowed the operation frequencies to increase, thereby

improving reliability.     One notable advance in radio communication has been the

FCC approval of a technology known as Spread Spectrum radio.  This is an

unlicensed 900 Mhz frequency ‘hopping’ technique that provides reliable

communication within about a 15-mile range.  The range can be extended with a

repeater configuration.



Project Phases:  Due to the complex nature of installing a SCADA system into an

irrigated area, successful implementation is best accomplished in phases.

Initiating change in the routine operation of key facilities and altering the day-to-

day activities of company or district personnel can create significant uncertainty.

It is therefore necessary that this uncertainty is addressed during each step of the



                   Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 10-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                     Water Measurement and Water Balances. San Luis Obispo, CA.

        http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf   ITRC Paper No. P02-004



process and a level of confidence is gradually built-up in the participants.

Achieving this critical “buy-in” from the people who will actually use the system

is essential for the success of modernization projects.  This phased approach has

the important benefits including maximizing reliability while allowing an

irrigation company or district to prioritize critical modernization needs and

implement components on a site-by-site basis.  Styles et al. ( 1999) outline further

advantages of the phased approach based on experience in modernization projects

in irrigation districts.  The Project Phases used for installing a SCADA system for

SMWC were as follows:



Phase 1 (Completed in April 2001):  The first phase of the SCADA part of the

project was to install, test and calibrate a new water level sensor in the head of the

main canal at Portuguese Bend.         The new sensor located in a stilled area at the

start of the canal was connected to the RTU/PLC at the Portuguese Bend pumping

plant.  The new sensor installation was setup so that water levels in the canal were

measured once per second and transmitted via radio to the RTU/PLC, where it

was stored in a data table and averaged over a one-minute time interval.  Upon

completion of this task, the Lookout® screens at the district office included

information on the canal water levels at two locations, the river stage, the status of

each pump (on/off and speed) and target depth (water level setpoint).  In addition,

the Lookout® screens were configured so that the target depth could be remotely

changed from the office (for future automatic control), and so that up to

15 coefficients used for the distributed automatic control could be remotely

changed from the office.       However, the ability to change these coefficients were

“hidden” so that only authorized personnel will be able to change the values.



Phase 2 (Completed in June 2001):  This was the first step toward automating the

site but nothing automatic was introduced at this stage.  The VFD pump was

tested on-site in manual mode with occasional remote manual operation.  Manual

VFD operation means the operator sets the motor speed control using the percent

speed control located in the pumping plant.  This phase facilitated testing of the

new communications equipment, sensors, VFD controls, connection to the office

computer, a new air/vacuum relief valve, etc.



Phase 3 (Completed in October 2001):            This was the second step toward

automating the site.     There was a continuation of the remote manual mode of

operation, but it was expanded to include a new flow meter.  Rather than using

only water levels as feedback, the operators now had information on specific flow

rates at the pumping plant.      A new electronic flow measurement device

(Panametrics acoustic meter) was installed on one of the three pumping units and

the flow rate was available to the operator.  The digital display screens for the

new Panametrics meters are shown in Figure 4.  This did not mean that operators

were expected to make hourly changes from the remote office location.  This step

required at least two months of operational testing extending into the peak

irrigation season.



                   Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 11-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                     Water Measurement and Water Balances. San Luis Obispo, CA.

        http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf   ITRC Paper No. P02-004



Phase 4 (Completed in  December 2001):  This was the third and final step of

automating the Portuguese Bend pumping plant.  A Proportional-Integral-Filtered

(PIF) algorithm for control of the site was programmed into the RTU/PLC and

implemented.      The control algorithm was a PIF algorithm supplied by the ITRC

and not the internal Proportional-Integral (PI) equation supplied by the VFD’s

manufacturer.



The Lookout® screens in the office necessary to support this automation were

already in-place.     The ladder logic and additional site programming were

completed during this stage.       At this time the effect of fluctuations in the

Sacramento River level was factored in and added to the ladder logic

programming, allowing the minimum VFD speed to shift with the river level.

The Lookout® screens were modified to allow a person in the remote office

location the ability to shift the pumps to automatic or manual control.              In the case

of remote manual control, this meant the ability to control the speed of the VFD

and the number of pumps operating from the office.              This final step allowed for

the fullest possible (or desirable) automation of the site.



   Figure 4.  Digital display screens for new Panametrics flow meters inside the

                              Portuguese Bend pumping plant



CANALCAD Modeling:              During the modernization effort, the ITRC completed

several unsteady flow hydraulic simulations of the first pool of the Portuguese

Bend canal were conducted to determine the optimum control scheme for the new

VFD unit.  The algorithm uses PIF control logic based on water depth

measurements 1,800 feet downstream of the Portuguese Bend pumping plant.



                   Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 12-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                          Water Measurement and Water Balances. San Luis Obispo, CA.

          http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf                   ITRC Paper No. P02-004



The algorithm controls that water depth using the VFD and single stage pumps in

the pumping plant.



The following is the control logic with optimized algorithm parameters:



                       VFD pump speed change:                        DS =1.3 * Round (DQ, 3)

                       Required flow rate change:                    DQ=35.315*[KP*(FE1-

                       FE2)+(KI*FE1)]

                                             with:                   FE1 =fc*FE2+(1-fc)*ENOW

                                                                    FE2 = FE1 of previous step.

                                                                    KP = -6.50

                                                                    KI = - 0.18

                                                                    fc = 0.84



Simulation Results:             Figure 5 summarizes the best modeling results and algorithm

for controlling the water depth about three-quarters of the way downstream from

the Portuguese Bend canal.



                        Sutter Mutual Water Co. Portugese Bend Pumping Plant (CC STN 1+00)



                                                       PB_20RT5.ccd, PB_20RT5.xls, PB_PIF1.FOR



      6                                                                                                                 250

                   Water depth MTx3 2300 feet d/s of pumps KP = - 6.5

                   yt

                                                          KI   = - 0.18

                   Water depth MTx2 1800 feet d/s of pumps                                                              225

                   Water depth at immediately d/s of pumps fc  =  0.84

       5           Pumping plant flow(cfs)

                                                                                                                        200



                                                                                                                        175  )

                                                                                                                            S

      4                                                                                                                     F

                                                                                                                            C

                                                                                                                            (

                                                                                                                             

                                                                                                                             e

                                                                                                                        150  t

                                                                                                                             a

    )                                                                                                                       R

    t                                                                                                                        

    f                                                                                                                        w

    (

                                                                                                                             o

    h                                                                                                                       l

    t  3                                                                                                                125  F

    p                                                                                                                        

    e                                                                                                                       t

                                                                                                                             n

    D                                                                                                                        a

                                                                                                                            l

    r                                                                                                                       P

    e                                                                                                                        

    t                                                                                                                   100  g

    a

                                                                                                                             n

    W                                                                                                                       i

                                                                                                                             p

      2                                                                                                                      m

                                                                                                                             u

                                                                                                                        75  P



                                              - Control of pumping plant is based on transducer 1800 feet d/s of pumps with the

                                                                                                                        50

       1                                      goal of controling a 3.4' depth at that location

                                              - CanalCAD v2.04 simulation uses 1 sec computational TS with 1 min control TS

                                              based on the average of 60 "yest" values                                  25

                                              - TO flow change ramp time =absolute(flow rate change)*(5min/10CFS), output

                                              generated every 6 sec

       0                                                                                                                0

       0:00                                 6:00                                12:00                               18:00



                                                            Time (h)



Figure 5.  Water level control results when turnout flow changes occur at a rate of

                                     5 minutes for every 10 cfs change



The control action occurs once a minute based on the average of at least

60 measurements of water depth.                     The graph presents the control results for nine



                       Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 13-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                               Water Measurement and Water Balances. San Luis Obispo, CA.

            http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf                                 ITRC Paper No. P02-004



simulated end-of-canal turnout flow changes that range from 5 to 110 cfs and that

occur over an 18-hour period.                           The turnout flow changes occurred based on five

minutes per every 10 cfs change in flow.



The graph shows the following information:



                    − Water depth immediately downstream of the pumping plant,

                    − Target water level of 3.4 ft at 1,800 ft downstream of the pumping

                           plant,

                    − Water depth at 1,800 ft downstream of the pumping plant,

                    − Water depth at 2,300 ft (end of the pool), and

                    − Pumping plant flow rate



Figure 5 demonstrates satisfactory water level control with frequent flow rate

changes over a relatively short period of time using the ITRC selected control

                                                                                             6

algorithm.  The target water level to maintain is 3.4   ft and the control location is

1,800 ft downstream of the pumping plant.                                       This is the location of two transducers

                                                7

for measuring water depth  .



                                                  VFD Documented Response and CanalCAD Results

                                                   Sutter-Mutual Water Company, Portuguese Bend

                                                                 December 11, 2001



     7.5                                                                                                                                 80

                                                                                               Actual water depth 1800 feet d/s of pump, ft



                                                                                               Predicted water depth 1800 feet d/s of pump, ft

     7.0                                                                                       Water level target = 5.6 ft               70



                                                                                               Approximate demand flow rate, cfs

                                                                                               VFD pump speed, %



     6.5                                                                                                                                 60

                                                  Predicted water level

                                                    from CanalCAD

                                                                                                                                             %    s

     6.0                                                                                                                                 50       f

                                                                                                                                              ,   c

                                                                                                                                             p     ,

 t                                                                                                                                                e

 f

                                                                                                                                             m    t

  ,                                                                                                                                          u    a

 h

 t                                                                                                                                           P    R

 p                                                                                                                                                  

 e   5.5                                                                                                                                 40  D    w

 D                                                                                                                                           F    o

                                                                                                                                                  l

 r                                                                                                                                           V    F

 e

 t                                                                               Actual water level

 a

 W

     5.0                                                                                                                                 30



     4.5                                                                                                                                 20



                                                                    Demand flow changed from 20 cfs

     4.0                                                                                                                                 10

                                                                             to 4 cfs at 9:05



     3.5                                                                                                                                 0

       7:45       8:00      8:15       8:30      8:45       9:00      9:15       9:30       9:45      10:00     10:15      10:30     10:45



                                                                          Time



   Figure 6.         Documented VFD response, water level control results and predicted

                              water depth with an 80% change in demand flow



6 The target water level was later changed to 5.6 ft after the canal was de-silted



and the sensor height adjusted.

7 A redundant measurement (Y2) is used to check the integrity of the (Y1)



measurement, which is used in the control logic.



                            Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 14-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                    Water Measurement and Water Balances. San Luis Obispo, CA.

        http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf  ITRC Paper No. P02-004



Documented VFD Response:            The documented response of the Portuguese Bend

pumping plant from field tests conducted in December 2001 is shown above in

Figure 6.   During the final evaluation, the demand flow was varied with multiple

flow rate changes to test the response time, stability and robustness of the VFD

and SCADA systems.         The flow changes were made manually by the operator

adding or removing weir boards and opening or closing the gate at the check

structure located at the downstream end of the first pool of the Portuguese Bend

canal.



      PROJECT #2:         ELECTRONIC WATER FLOW MEASUREMENT



The second project of the modernization program at the SMWC was the

successful utilization of advanced flow measurement technologies.               Accurate flow

measurement is an integral part of the scientific management of water and energy

resources.  New electronic flow measurement devices provide a cost-effective and

practical means to precisely measure flows at critical locations such as the

pumping plant at Portuguese Bend.          Panametrics, SonTek Argonaut™ SL and

Unidata Starflow ultrasonic flow meters were used to determine flow rates and

volumetric flow in the discharge pipeline and canal at Portuguese Bend in

conjunction with the evaluation of the new VFD and SCADA system.                    A brief

overview of the deployment of these devices is presented in the following

sections.



Testing in the Portuguese Bend Pumping Plant’s Main Canal



The new VFD pump permits excellent control of the water level in the first pool

of the canal by allowing an unlimited flow rate range.  However, in order to

correctly program the RTU/PLC of the VFD, the relationship between “change in

pump speed” and “change in flow rate” must be known.  In practice, this is

neither a constant nor a precisely known value.  The ITRC used ultrasonic flow

measurement equipment on the VFD pump discharge pipeline and pump affinity

laws to estimate the relationship between pump speed and flow rate.               A

Panametrics acoustic flow meter was installed on the VFD pump discharge

pipeline in order to integrate real-time flow data into the new SCADA system, in

addition to providing flow rate via a digital display in the pumping plant (refer to

Figure 4).



Testing in the Tisdale Pumping Plant’s Main Canal at the Tisdale Bridge



A SonTek Argonaut™ SL Doppler current meter (Figure 7) was deployed in the

Tisdale main canal near Tisdale Bridge from April 18 to July 31, 2001.  The canal

flow rate was measured in 10-minute intervals and the daily flow volume was



                  Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 15-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                     Water Measurement and Water Balances. San Luis Obispo, CA.

        http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf    ITRC Paper No. P02-004



calculated.  The daily flow volume measured by the SonTek Argonaut™ SL was

compared to data provided by SMWC.  Drawings of the canal cross-sections at

the deployment location were prepared and used in the calculation of volumetric

flows.   The Tisdale Bridge location is shown in Figure 7 below.



     Figure 7.   SonTek Argonaut™ SL Doppler current meter at Tisdale Bridge



The percent difference in the measured volume of delivered water ranged from

1.4 to 2.6% per month while the percent difference in total delivered volumes

during the four months was less than one percent (–0.9%) as shown in Figure 8.

In both monthly and total volumes, the meter registered the slightly higher

amount.



                   Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 16-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                            Water Measurement and Water Balances. San Luis Obispo, CA.

           http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf                        ITRC Paper No. P02-004



                                     Sutter-Mutual Water Company, Tisdale Bridge

                                        SonTek Argonaut SL and River Diversions

                                                        April to July, 2001

       1,6 00



       1,4 00



       1,2 00

   t

  f

    -

   c   1,0 00

   a

   

    ,

   e

   m    8 00

   u

  l

   o

  V

        6 00                                                                    SonTek Volumetric Flow, ac-ft

   w

   o

  l

  F     4 00                                                                    Sutter-Mutual River Diversions, ac-ft



        2 00



           0

         4/18 /2 00 1  4/28 /2 00 1 5/8/20 01 5/18/20 01 5/2 8/20 01 6 /7/20 01 6/17/20 01 6/27/20 01 7/7/2 00 1 7/17/20 01 7/27/20 01



                                                         Irrigation Day



        Figure 8.       Comparison of Sutter Mutual Water Company and the SonTek

                            Argonaut SL volumetric flows at Tisdale Bridge



Testing at Portuguese Bend Canal



To facilitate the final evaluation testing of the VFD and SCADA system at

Portuguese Bend, a Unidata Starflow acoustic Doppler flow meter (Figure 9) was

installed in the canal approximately 200 ft downstream of the pumping plant.                                                   The

Unidata Starflow ultrasonic flow meter provided the total flow rate from the

pumping plant during the test period.  This was necessary because the new

Panametrics meter had not yet been installed on pump #3 (single stage) at the

pumping plant.  The Unidata Starflow meter was field calibrated using the

Panametrics flow meter on pump #1.



                         Irrigation Training and Research Center (ITRC) – www.itrc.org


----------------------- Page 17-----------------------

 Presented at the July 9-12, 2002 USCID conference on Benchmarking Irrigation System Performance Using

                    Water Measurement and Water Balances. San Luis Obispo, CA.

        http://www.itrc.org/papers/modernsmwc/modernizingsmwc.pdf ITRC Paper No. P02-004



  Figure 9.  Digital display LCD screen on the Unidata Starflow acoustic Doppler

                                         flow meter



                                        SUMMARY



In summary, the modernization effort at SMWC is still continuing in the year

2002 when the company hopes to install a SCADA system in its Tisdale pumping

plant.   Savings resulting from the installation of the VFD and SCADA system at

the Portuguese Bend pumping plant are being closely monitored and already have

shown important benefits to the water company and reclamation district as a

whole, especially in the area of conserved water and reduced energy costs.



                                      REFERENCES



Styles, S.W., C.M. Burt, M. Lehmkuhl, and J. Sweigard.            1999.   Case Study:

Modernization of the Patterson Irrigation District.  Presented at the USCID

Workshop on Modernization of Irrigation Water Delivery Systems.                Oct. 17-21,

1999.   Phoenix, Arizona.



                  Irrigation Training and Research Center (ITRC) – www.itrc.org