Addressing control applications using wireless hart devices

Addressing Control Applications Using

WirelessHART Devices

Marty Zielinski - Director of HART and

Fieldbus Technology

Mark Nixon – Director, Research

Terry Blevins – Principal Technologist

Presenters

Marty Zielinski

Terry Blevins

Mark Nixon

Introduction

The PIDPlus capability in DeltaV may be used to

implement closed loop control using WirelessHART

devices. In this workshop we address

Wireless Impact on Control

PIDPlus for Control Using Wireless Measurements

Performance Comparison to Wired Transmitter

Addressing Lost Communications

Test results – Field Installations

The PIDPlus may be used with slow and variable

communication updates

Challenge – Control Using WirelessHART

Transmitter power consumption may be minimized by reducing the

number of times the measurement value is communicated.

Conventional PID execution synchronizes the measurement value

with control action, by over-sampling the measurement by a factor of

2-10X.

The rule of thumb to minimize control variation is to have feedback

control executed 4X to 10X times faster than the process response

time (process time constant plus process delay).

The conventional PID design (i.e., difference equation and z-

transform) assumes that a new measurement value is available at

each execution and that control is executed on a fixed periodic

basis.

Conventional Approach – Over Sampling of Measurement

Control Execution

63% of Change

Process Output

Process Input

Deadtime (TD )

O

I

New Measurement Available

Time Constant ( )

Conventional PID - Impact of Wireless

The underlying assumption in traditional control design is that the

PID is executed on a periodic basis 4X-10X times over the process

response time .

When the measurement update is variable or updated less

frequently, the calculated reset action may not be appropriate.

If control action is only executed when a new measurement is

communicated, this could result in a delayed control response to

setpoint changes and feedforward action on measured disturbances.

Conventional PID Design

Emerson’s WirelessHART Solution

Power consumption of the wireless device is reduced by

transmitting the measurement value only as often as required

to allow control action to correct for unmeasured disturbances.

The PID may be configured to execute much faster than the

measurement value is communicated. The PIDPlus is

designed to automatically compensate for the slower

measurement update and any variation in measurement

update rates.

Tuning of the PIDPlus is based strictly on the process

dynamics independent of the measurement update rate and is

not impacted by variations in measurement update.

Conventional PID - Impact of Wireless

The underlying assumption in traditional control design is that the

PID is executed on a periodic basis 4X-10X times over the process

response time .

When the measurement update is variable or updated less

frequently, the calculated reset action may not be appropriate.

If control action is only executed when a new measurement is

communicated, this could result in a delayed control response to

setpoint changes and feedforward action on measured disturbances.

Conventional PID Design

PIDPlus for WirelessHART Communications

To provide the best control for slow or variable measurement update

rates, the PID must be modified to reflect the reset contribution for

the expected process response since the last measurement update.

Control execution is set faster than measurement update. This

permits immediate action on setpoint change and update in the

faceplate.

PIDPlus is a standard feature of DeltaV v11.3 (released 2010)

PIDPlus Design in DeltaV v11.3

PIDPlus Reset (Integral) Calculation

The filter output used in the positive feedback network is calculated in the

following manner when a new measurement is received.

PIDPlus tuning is based on the process dynamic (e.g. RESET= process

time constant plus deadtime); PIDPlus reset automatically compensates

for slow updates and variations in the measurement update rate. No

change in GAIN is required for varying update rate.

PIDPlus Modification for Setpoint Change

Automatic compensation for setpoint change; measurement update

rate. No need to modify tuning as sample rate changes

PIDPlus –DeltaV v12.3 release in 2012

No Yes

PIDPlus Using Wireless Transmitter vs. Conventional PID and Wired Transmitter

Control

Measurement

Control Output

Unmeasured

Disturbance

Setpoint PIDPlus

PIDPlus

PID

PID

Lambda Tuning ʎ = 1.0

Variable communication Update Rate

CONTROL PERFORMANCE DIFFERENCE

Communications transmissions are reduced by over 96 %

using slower communication update rates.

The impact of slower updates and variations in

measurement updates on control performance as

measured by Integral of Absolute Error (IAE) is minimized

through the use of PIDPlus for wireless communication.

Communications/Control Number of

Communications

IAE

Periodic/standard PI Controller 692 123

Update Using Wireless

communication/ PI Control

25 159

PIDPlus - Modified Derivative Action

No Yes

PID Performance for Lost Communications

The Conventional PID provides poor dynamic

response when wireless communications are lost.

The PIDPlus improves the dynamic response

under these conditions

Wireless Communication Loss – During Setpoint Change

Communication Loss

PID

PIDPlus

PIDPlus

PID

Control

Measurement

Control Output

Setpoint

Wireless Communication Loss – During Process Disturbance

Communication Loss

PIDPlus

Setpoint Control

Measurement

Control Output

PID

PIDPlus

PID

Testing PIDPlus –Communication’s Setup

For testing purposes, the WirelessHART communications and the

process can be dynamically simulated in a DeltaV module for PID and

PIDPlus control.

Communication setup is defined by the “Transmission” composite block.

Installation at Broadley James

Portable Hyclone 100 liter disposable bioreactor

Rosemount WirelessHART gateway and transmitters for measurement and control of pH and temperature. Pressure monitored

BioNet is based on the DeltaV Control system.

Installation at Broadley James (Cont)

Detail view of Rosemount pH WirelessHART Transmitter.

Battery powered – 3 to 5 year battery life expected for this application.

Broadley James Bioreactor Setup

Bioreactor

VSD

VSD

TC

41-7

AT

41-4s2

AT

41-4s1

AT

41-2

AT

41-1

TT

41-7

AT

41-6

LT

41-14

Glucose

Glutamine

pH

DO

Product

Heater

VSD

VSD

VSD

AC

41-4s1

AC

41-4s2

Media

Glucose

Glutamine

VSD

Inoculums

VSD

Bicarbonate

AY

41-1

AC

41-1Splitter

AC

41-2

AY

41-2Splitter

CO2

O2

Air

Level

Drain

0.002 g/L

7.0 pH

2.0 g/L

2.0 g/L

37 oC

MFC

MFC

MFC

AT

41-5x2

Viable

Cells

AT

41-5x1

Dead

Cells

Bioreactor

VSDVSD

VSD

TC

41-7

TC

41-7

AT

41-4s2

AT

41-4s1

AT

41-2

AT

41-1

TT

41-7

AT

41-6

LT

41-14

Glucose

Glutamine

pH

DO

Product

Heater

VSD

VSD

VSD

AC

41-4s1

AC

41-4s1

AC

41-4s2

AC

41-4s2

Media

Glucose

Glutamine

VSD

Inoculums

VSD

Bicarbonate

AY

41-1

AC

41-1

AC

41-1Splitter

AC

41-2

AC

41-2

AY

41-2Splitter

CO2

O2

Air

Level

Drain

0.002 g/L

7.0 pH

2.0 g/L

2.0 g/L

37 oC

MFC

MFC

MFC

AT

41-5x2

Viable

Cells

AT

41-5x1

Dead

Cells

Example - Automatically Identified Temperature Dynamics Using DeltaV Insight Example - Automatically Identified Temperature Dynamics Using DeltaV Insight

DeltaV Insight – Standard Since DeltaV v9.3

Wireless Temperature Loop Test Results Wireless Temperature Loop Test Results

Wireless pH Loop Test Results Wireless pH Loop Test Results

Elimination of Ground Noise Spikes Elimination of Ground Noise Spikes

Wired pH ground noise spike

Temperature compensated wireless pH controlling at 6.9 pH set point

Requirement:

Tight pH control via 0.001 pH wireless resolution setting

Separations Research Program, University of Texas at Austin Separations Research Program, University of Texas at Austin

The Separations Research Program was established at the J.J. Pickle Research Campus in 1984

This cooperative industry/university program performs fundamental research of interest to chemical, biotechnological, petroleum refining, gas processing, pharmaceutical, and food companies.

CO2 removal from stack gas is a focus project for which WirelessHART transmitters were installed for pressure and steam flow control

WirelessHART Transmitter WirelessHART Transmitter

Standard WirelessHART

pressure and flow transmitters

were installed to demonstrate

and test control using

WirelessHART.

Standard WirelessHART pH

transmitters are used to support

studies associated with CO2

removal from stack gases.

Standard WirelessHART multi-

element temperature

transmitters are used to monitor

absorber and stripper

temperatures.

Steam Flow To Stripper Heater Steam Flow To Stripper Heater

Column Pressure Control Column Pressure Control

PC215 On-line Column Pressure Control PC215 On-line Column Pressure Control

The same dynamic control response was observed for SP changes

Original plant PID tuning was used for both wired and wireless control

GAIN=2.5

RESET=4

RATE=1

Wired Measurement

Used in Control

Wireless Measurement

Used in Control

Control Performance – Wired vs Wireless Control Performance – Wired vs Wireless

Comparable control as measured by IAE was achieved using WirelessHART Measurements and PIDPlus vs. control with wired measurements and PID.

The number of measurement samples with WirelessHART vs Wired transmitter was reduced by a factor of 10X for flow control and 6X for pressure control – accounting for differences in test duration.

LOOP FIC202 PC215 FIC202 PC215

Selected Input Wired Wired Wireless Wireless

IAE 9134 145 10645 198

Number of

Communication

13655 6649 1184 912

Test Time (sec) 6830 6829 5926 5925

Test 1 Test 2

Separations Research Program, University of Texas at Austin Separations Research Program, University of Texas at Austin

The Separations Research Program was established at the J.J. Pickle Research Campus in 1984

This cooperative industry/university program performs fundamental research of interest to chemical, biotechnological, petroleum refining, gas processing, pharmaceutical, and food companies.

CO2 removal from stack gas is a focus project for which WirelessHART transmitters were installed for pressure and steam flow control

Current Product: Discrete Control

Video

Currently in 7 End User Field Trials Sites 7 different applications 6 industrial market segments

Release planned for the end of 2012

Future Product: 4300 Series Wireless On/Off Control

Business Results Achieved

The PIDPlus allows WirelessHART devices to be

used for closed loop control of quality parameters

that currently may not be available in the control

system.

The reduction in process variability achieved through

closed loop control may lead to improved process

operation e.g. reduction in product quality variation,

improved efficiency.

Field installations have documented robust control

performance using the PIDPlus with WirelessHART

transmitters. The results were shown for control of

liquid flow, gas pressure, pH and temperature.

Summary

WirelessHART measurements may be used in closed loop

control applications.

– Slower reporting minimizes power consumption

PIDPlus is a standard feature of DeltaV and works with

standard WirelessHART devices.

– Standard DeltaV Tools support Simulation and Tuning

The performance of PIDPlus in a wireless control network is

comparable to PID with wired inputs

– PIDPlus handles lost communications better than

conventional PID.

PIDPlus tuning depends only upon process dynamics, not on

wireless update rate

Where To Get More Information

PID Advances in Industrial Control, IFAC Conference on Advances in PID Control PID'12,

Brescia, Italy, 28-30 March 2012 http://pid12.ing.unibs.it/sp_blevins.html

DeltaV v11 PID Enhancements for Wireless, DeltaV Whitepaper, August, 2010

http://www2.emersonprocess.com/siteadmincenter/PM%20DeltaV%20Documents/Whitepap

ers/WP_DeltaV%20PID%20Enhancements%20for%20Wireless.pdf

WirelessHART Successfully Handles Control, Chemical Processing, January, 2011

http://www2.emersonprocess.com/siteadmincenter/PM%20Articles/WirelessHART%20Succ

essfully%20Handles%20Control.pdf

Wireless – Overcoming Challenges of PID Control& Analyzer Applications, InTech,

July/August, 2010

http://www.isa.org/InTechTemplate.cfm?template=/ContentManagement/ContentDisplay.cfm

&ContentID=83041

PIDPlus An Enhanced PID Control Algorithm for Wireless Automation, AS-74.3199 Wireless

Automation, Aalto University, Finland http://autsys.tkk.fi/intranet/as-0.3200/attach/S09-

19/loppuraportti.pdf

Incorporating Wireless Devices into Single-Use Disposable Bioreactor Design, 2009

Dhirubhai Ambani Life Sciences Symposium http://www.modelingandcontrol.com/Wireless-

Devices-in-Single-Use-Bioreactors.pdf

Improving PID Control with Unreliable Communications, ISA EXPO Technical Conference,

2006. http://www.automation.com/pdf_articles/10_improving_pid.pdf

Similarity-based Traffic Reduction to Increase Battery Life in a Wireless Process Control

Network, ISA EXPO2005, Houston, TX www.cs.utexas.edu/~sjp/publications/isa06.doc