PLC 4 PRIMARY SEDIMENTATION SYSTEM SCADA SYSTEM OPERATION … Primary... · 2013-10-08 · PLC4 – Primary Sedimentation System (Allen Bradley PLC5 - Main PLC Rack) Fig-1; PLC-4

PLC 4 – PRIMARY SEDIMENTATION SYSTEM

SCADA SYSTEM OPERATION MANUAL Revision 1.0

May 15, 2006

Meyer Control Corporation Stockton RWCF WW32 / WW39 CH2M Hill / OMI – Thames Water

PLC 4 PRIMARY SEDIMENTATION SYSTEM

SCADA SYSTEM OPERATION MANUAL Revision 1.0 May 15, 2006

Table of Contents 1 Introduction............................................................................................................................................................................................................ 4 2 Revision History .................................................................................................................................................................................................... 4 3 PLC System Overview........................................................................................................................................................................................... 4 4 Conventions ........................................................................................................................................................................................................... 6

4.1 Set Points and Process Values ...................................................................................................................................................................... 6 4.2 Equipment Colors ......................................................................................................................................................................................... 6 4.3 Line sizes and colors .................................................................................................................................................................................... 6 4.4 Instrument Bubbles....................................................................................................................................................................................... 7

5 New Control Strategies .......................................................................................................................................................................................... 7 5.1 Primary Sludge Pumps ................................................................................................................................................................................. 7

5.1.1 Abandoned or Removed Instrumentation ................................................................................................................................................ 7 5.1.2 Sludge Pump System Modes.................................................................................................................................................................... 8 5.1.3 Pair Operating Modes .............................................................................................................................................................................. 8 5.1.4 Pump Monitoring and Control ................................................................................................................................................................. 9 5.1.5 Flow Control ............................................................................................................................................................................................ 9 5.1.6 Interlocks................................................................................................................................................................................................ 10

5.2 Secondary Sludge Pumps ........................................................................................................................................................................... 10 5.2.1 Secondary Sludge Pump System Modes ................................................................................................................................................ 10 5.2.2 Pump Monitoring and Control ............................................................................................................................................................... 10 5.2.3 Flow Control .......................................................................................................................................................................................... 11 5.2.4 Interlocks................................................................................................................................................................................................ 11

6 Sample SCADA Screens...................................................................................................................................................................................... 13 6.1 Primary Sedimentation Overview .............................................................................................................................................................. 14

May 15, 2006– Rev. 1.0 PLC 4 Primary Sedimentation System – SCADA System Operation Manual Page 2 of 37


6.2 Process Areas 10–15 Menu ........................................................................................................................................................................ 15 6.3 Scum Collector Pop-up............................................................................................................................................................................... 16 6.4 Sludge Collector Pop-up............................................................................................................................................................................. 17 6.5 Primary Flow Distribution Screen.............................................................................................................................................................. 18 6.6 Scum Box and Pumps................................................................................................................................................................................. 19 6.7 Scum Box and Pumps Set Points................................................................................................................................................................ 20 6.8 Scum Pump Pop Up.................................................................................................................................................................................... 21 6.9 Scum Box 2 and 3....................................................................................................................................................................................... 22 6.10 Sludge Box and Pumps............................................................................................................................................................................... 23 6.11 Sludge Flow Control Loop ......................................................................................................................................................................... 24 6.12 Sludge Pump Pop Up.................................................................................................................................................................................. 25 6.13 Flow Transmitter Pop Up ........................................................................................................................................................................... 26 6.14 Primary Tank Drainage / Recycle Pump Station........................................................................................................................................ 27 6.15 Primary Tank Drainage Set Points ............................................................................................................................................................. 28 6.16 Primary Sludge Pump Summary ................................................................................................................................................................ 29 6.17 Secondary Sludge Pumping........................................................................................................................................................................ 30

7 Sample Panel View (OIT) Screens ...................................................................................................................................................................... 31 7.1 Primary Sedimentation System Overview Screen...................................................................................................................................... 32 7.2 Sludge Box 1 and Pumps............................................................................................................................................................................ 33 7.3 Sludge Box 2 and Pumps............................................................................................................................................................................ 34 7.4 Sludge Pumps 1-8 Set points ...................................................................................................................................................................... 35 7.5 Secondary Sedimentation Tank .................................................................................................................................................................. 36 7.6 Secondary Sludge Pumps Control .............................................................................................................................................................. 37



PLC 4 PRIMARY SEDIMENTATION SYSTEM

SCADA SYSTEM OPERATION MANUAL

Revision 1.0

May 15, 2006 1 Introduction This document presents the operational logic and sample SCADA and OIT (local operator interface terminal) screens for the Primary Sedimentation System at the Stockton Regional Wastewater Control Facility.

2 Revision History The table below shows the history of revisions to this document.

Rev. Description By Date1.0 Issued for customer training Max Hanson/

Imran Saeed May 15, 2006

3 PLC System Overview PLC4 was an existing controller for the primary sedimentation systems. Modifications in PLC4 were made to accommodate the primary and secondary sludge pumps upgrade and for establishing communication to the plant new SCADA system over Ethernet network. The PLC4 operation block diagram is shown in the Fig-1 below. An Operator Interface Terminal (OIT) is connected to the DH+ network channel on the main PLC rack, for allowing the plant operator to monitor and control the process locally. The RIO network channel on the main PLC rack is communicating to a remote I/O rack through RIO adapter. The new VFDs for the primary and secondary sludge pumps are controlled via a second remote I/O channel; all command and status data is transmitted as RIO data and no hard-wired inputs or outputs are used, and there are total 12 VFDs are connected in daisy-chain to this second remote I/O channel. A new Ethernet network communication card is also added to PLC4, for its communication to the plant main SCADA system over fiber optic Ethernet network.


Meyer Control Corporation

Process instrumentation such as pressure, level and flow transmitters are wired to themonitors the process values from its analogue and digital input channels. When the ccontrol outputs for achieving the desired process conditions according to the process operator can control the p ocess by manually entering the values through OIT.

PLC4 operation is further explained by the block diagram below (Fig-1).

RIO Network RIO Network RIO N

RIO Network RIO Network RIO N

Primary/Secondary Slud e Pumps (Allen Bradley PLC5 - Rem te I/O Rack)

DH+ Network

OIT (Operator Interface

Terminal)

Digital Output Channels

RIO Communication

Adapter

Analogue Input Channels

VVFD VFD VFD VFD VFD

VVFD VFD VFD VFD VFD

RIO Network

RIO Network

RIO Network

Fig-1; PLC-4 Operation

May 15, 2006– Rev. 1.0 PLC 4 Primary Sedimentation System – SCADA S

Stockton RWCF WW32 / WW39 CH2M Hill / OMI – Thames Water

I/O and communication channels of the PLC. The PLC ontrol mode is in AUTO, the PLC determines the necessary set points entered by the operator. In Manual mode the plant

DH+ RIO1 RIO2

CPU (Control Logic

Processing)

Ethernet Network

Communication.CH

Digital Input Channels

PLC4 – Primary Sedimentation System (Allen Bradley PLC5 - Main PLC Rack)

r

go

etwork

etwork

Ethernet (RJ45)

Ethernet (RJ45)

FC

Plant Central SCADA

FC

Fiber optic

FD

FD

Fiber/Copper Converter

Fiber/Copper Converter

Block Diagram

ystem Operation Manual Page 5 of 37


4 Conventions

4.1 Set Points and Process Values Set points appear with a black background inset field and white text. Process values will show an inset field with a white background and blue text. Status indicators also have the white inset field, but the foreground color may change depending upon the conditions and the background will turn yellow for abnormal situations.

Status Indicator Text Colors:

Text Background MeaningDark Red White Not called, inactive, off Dark Green White Called, active, on Gray White Not ready, unavailable for PLC control Black Yellow Alarm, abnormal condition

4.2 Equipment Colors Symbols for motor-driven equipment are animated with colors to reflect status.

Foreground MeaningRed Not called, inactive, off Green Called, active, on Gray Not ready, unavailable for PLC control Yellow Alarm, abnormal condition

Valves symbols are also color-coded.

Foreground MeaningRed Closed Green Opened (or called to open if no feedback) Gray Not ready, unavailable for PLC control Yellow Alarm, abnormal condition

4.3 Line sizes and colors Where appropriate, major process lines are shown with 3D pipe symbols and are animated to show when fluid is flowing. Minor process lines are shown with a dark gray background and an animated foreground color. Minor process lines do not have 3D appearance and are smaller.



Foreground MeaningGray No flow is present

Blue

Plant waterCyan Miscellaneous minor process (e.g., scrubbant)

Yellow Sulfur dioxideLight Green Chlorine or sodium hypochlorite

Magenta Ferric Chloride Pink Polymer

Light Brown

Wastewater Teal Storm water

White AirDark Brown Sludge

4.4 Instrument Bubbles Many screens will be arranged to show process flow similar to a Process and Instrumentation Diagram (P&ID). Instrument bubbles will show tag names and will have the relevant process value displayed. These bubbles are animated and will turn yellow when an alarm is present at the instrument represented by the bubble. Clicking on the instrument bubble will open the appropriate pop-up screen (note that these symbols are not used for some existing instruments as the PLC logic does not include all the features necessary to support the pop up screen).

5 New Control Strategies PLC #4 was an existing controller for the primary sedimentation systems. Most of the existing logic was left unchanged; however, new control strategies were implemented for the primary and secondary sludge pumps. SCADA functions for the existing logic will emulate functions available on the existing Panelview operator interface.

5.1 Primary Sludge Pumps The existing sludge pumps are replaced with the new screw centrifugal pumps controlled by variable frequency drives. The VFDs are connected to PLC #4 using 1771 Remote I/O. This allows control and monitoring of the drives by the PLC without hardwired I/O.

5.1.1 Abandoned or Removed Instrumentation The existing control system includes level transmitters designed to monitor the sludge level in the sludge boxes. These instruments have never worked correctly and they will be abandoned in place when the sludge pumps are upgraded. Options for level control of the sludge pumps will be removed from the control strategies.



The existing controls also include pressure transmitters on the discharge of the sludge pumps. These transmitters are used for high and low pressure alarms. The pressure instruments will be removed from service when the pumps are replaced.

5.1.2 Sludge Pump System Modes

5.1.2.1 Cycle Mode The normal mode of operation is cycle mode. The operator enters a cycle frequency for the entire system and an “on” duration for each pump. At the start of the cycle, the active pump in the first pair will operate for its specified duration, followed by the active pump from the second pair and the third and fourth pairs in sequence. After the final pump has run all pumps will be off until the overall system frequency cycle time has expired. At this time the cycle will begin again with the first pair of pumps.

If the total “on” duration for active pumps exceeds the overall system frequency period, a warning notice will appear on the operator interface and the cycle will start over when the final pump stops.

If both pumps in a pair are selected for active duty, each will run one at a time in turn.

5.1.2.2 Continuous Mode Continuous mode is intended to provide a steady sludge flow to the gravity belt thickeners. In this mode the active pump in each pair will operate continuously at the selected flow rate. If both pumps in a pair are selected as active, only the lower-numbered pump will operate.

5.1.3 Pair Operating Modes The sludge pumps are arranged in pairs. Each pair of pumps serves a sludge box that is filled by two of the eight sedimentation tanks. Each pair of pumps has several operating modes.

BOTH OFFLINE – Neither pump is active

ALTERNATE – Active role alternates between pumps each cycle

PUMP A ACTIVE – The lower-numbered pump of the pair is active

PUMP B ACTIVE – The higher-numbered pump of the pair is active

BOTH ACTIVE – Both pumps are active



5.1.4 Pump Monitoring and Control

5.1.4.1 Operating Modes MANUAL – The pump starts and stops in response to pushbuttons. Speed may be set from the operator interface.

AUTOMATIC – The pump starts and stops in response to system operating conditions. Speed is controlled by the flow control loop.

5.1.4.2 Monitoring The following status points are monitored and displayed on the operator interface.

REMOTE – VFD is set for remote (PLC) control rather than local keypad control.

READY – Pump is ready for PLC control (in remote and not failed)

FAULT – VFD is reporting a fault condition.

FAIL – Either a fault has been present for a delay time or the VFD did not return a running status after being called for a delay period.

RUNNING – Motor is running.

CALLED – VFD is called to run by the PLC.

SPEED COMMAND – The speed requested by the PLC (%).

SPEED – Actual speed at which the VFD is operating (%).

CURRENT – Current output of the VFD to the motor (Amps).

RUNTIME – Reported in tenths of an hour.

LOW SUCTION PRESSURE – Monitored by a pressure switch in the suction piping.

5.1.5 Flow Control Each pair of pumps is equipped with a flow transmitter. A desired flow rate is entered for each pair and this flow target is used to control the speed of pump operation. A proportional-integral (PI) control algorithm maintains the flow rate at target by manipulating sludge pump speeds. This loop may be placed in manual so that the pump speeds can be adjusted manually while leaving start stop pump control in automatic.

Each flow transmitter includes low-low, low, high and high-high alarms with adjustable set points. A flow transmitter failure alarm is also posted if the signal from the instrument is out of range. An alarm disable function allows an operator to disable all alarms for a given transmitter.



5.1.6 Interlocks Interlock conditions will prevent a piece of equipment from operating. There are several interlocks that will stop a primary sludge pump.

A pump failure alarm is triggered if a VFD faults or fails to run when called to do so. This alarm latches until reset by an operator. A pump will not be called if it has failed.

A pressure switch monitors the suction pressure for each sludge pump. If low suction pressure is detected for a delay period, an alarm is posted. Like the pump failure, this alarm latches until reset by an operator.

Once the new gravity belt thickener (GBT) PLC system is installed, conditions of the GBT system will be monitored to allow or stop the sludge pumps. If the GBT bypass valve is not open, the GBT must be ready for the sludge pumps to operate in automatic mode.

5.2 Secondary Sludge Pumps The existing secondary sludge pumps will be replaced with new screw centrifugal pumps controlled by variable frequency drives. The VFDs are connected to PLC #4 using 1771 Remote I/O. This allows control and monitoring of the drives by the PLC without hardwired I/O.

5.2.1 Secondary Sludge Pump System Modes

5.2.1.1 Cycle Mode The normal mode of operation is cycle mode. The operator enters a cycle frequency for the entire system and an “on” duration for each pump. At the start of the cycle, the first pump will operate for its specified duration, followed by the second, third and fourth pumps in sequence. After the final pump has run all pumps will be off until the overall system frequency cycle time has expired.

If the total on duration for active pumps exceeds the overall system frequency period, a warning notice will appear on the operator interface and the cycle will start over when the final pump stops.

5.2.1.2 Continuous Mode Continuous mode is intended to provide a steady sludge flow to the gravity belt thickeners. In this mode all of the pumps that are in automatic mode and are ready for PLC operation will run at their respective flow set points.

5.2.2 Pump Monitoring and Control Unlike the primary sludge pumps, the secondary sludge pumps are not arranged in pairs. Each pump serves a single secondary sedimentation tank directly.



5.2.2.1 Operating Modes MANUAL – The pump starts and stops in response to pushbuttons. Speed may be set from the operator interface.

AUTOMATIC – The pump starts and stops in response to system operating conditions. Speed is controlled by the flow control loop.

5.2.2.2 Monitoring The following status points are monitored and displayed on the operator interface.

REMOTE – VFD is set for remote (PLC) control rather than local keypad control.

READY – Pump is ready for PLC control (in remote and not failed)

FAULT – VFD is reporting a fault condition.

FAIL – Either a fault has been present for a delay time or the VFD did not return a running status after being called for a delay period.

RUNNING – Motor is running.

CALLED – VFD is called to run by the PLC.

SPEED COMMAND – The speed requested by the PLC (%).

SPEED – Actual speed at which the VFD is operating (%).

CURRENT – Current output of the VFD to the motor (Amps).

RUNTIME – Reported in tenths of an hour.

LOW DISCHARGE PRESSURE – Monitored by a pressure switch in the discharge piping.

5.2.3 Flow Control Each pump is equipped with a flow transmitter. A desired flow rate is entered for each pump and this flow target is used to control the speed of pump operation. A proportional-integral (PI) control algorithm maintains the flow rate at target by manipulating sludge pump speeds. This loop may be placed in manual so that the pump speed can be adjusted manually while leaving start / stop pump control in automatic.

Each flow transmitter includes low-low, low, high and high-high alarms with adjustable set points. A flow transmitter failure alarm is also posted if the signal from the instrument is out of range. An alarm disable function allows an operator to disable all alarms for a given transmitter.

5.2.4 Interlocks Interlock conditions will prevent a piece of equipment from operating. There are several interlocks that will stop a secondary sludge pump.



A pump failure alarm is triggered if a VFD faults or fails to run when called to do so. This alarm latches until reset by an operator. A pump will not be called if it has failed.

A pressure switch monitors the discharge pressure for each sludge pump. If low discharge pressure is detected for a delay period, an alarm is posted. Like the pump failure, this alarm latches until reset by an operator.

Once the new gravity belt thickener (GBT) PLC system is installed conditions of the GBT system will be monitored to allow or stop the sludge pumps. If the GBT is not ready, a manual override will be required to run the secondary sludge pumps.

A high level alarm in the thickened sludge wetwell will stop the secondary sludge pumps once the GBT PLC system is online.



6 Sample SCADA Screens Sample SCADA screens for the Primary Sedimentation system follow. These are the screens that will appear on the plant SCADA system. Screens with similar function are available at existing Panelview local operator interface and would be shown in section 7 of this document. Please note that no process data was present when these screens were generated. This means that process values will show zero and it is operating scenarios that are not actually possible may be shown.



6.1 Primary Sedimentation Overview

This screen presents an overview of the primary sedimentation facilities. It shows operating status for the scum and sludge collectors for each tank.

Clicking on a sludge or scum box will launch another screen that shows the associated scum or sludge pumps and operating status.

Clicking in the status fields for the scum and sludge collectors opens a pop-up window that allows control of the equipment.

A click on the distribution structure launches a screen showing flow distribution for the primaries.

Clicking the Tank Drain symbol launches the drain pump station screen.

Clicking the Polymer or Ferric Chloride areas will open screens for those systems.



6.2 Process Areas 10–15 Menu

When the mouse is moved to the left edge of the screen, a context-sensitive navigation menu opens after a brief delay. The menu shown is typical for all of the primary sedimentation screens and allows one to jump quickly to other areas at the front end of the plant.



6.3 Scum Collector Pop-up

This illustrates the pop-up screen for a scum collector. With the right security access, an operator can manually start and stop the collector from this screen.

Status indicators change color as well as text to show current status. The start and stop buttons are disabled when in automatic mode.



6.4 Sludge Collector Pop-up

The pop-up screen for a sludge collector is illustrated to the left. The sludge collectors do not have automatic mode. They are started and stopped manually by pushbutton and generally run continuously.



6.5 Primary Flow Distribution Screen

This screen shows how flow is distributed to the primary sedimentation tanks. Levels in the distribution structure and influent box #2 are displayed with bar graphs.

Weir gates are used to control flow rates. Like the levels, weir gate positions are shown with accompanying bar graph indicators.

Flow rates are measured at each weir gate and by a flow meter at the drain pump station. These flow rates and totals are displayed. Total influent flow rate is calculated by the PLC by adding the flow rates at the weir gates. Each flow total may be individually reset from this screen.



6.6 Scum Box and Pumps

A typical scum box is fed by two sedimentation tanks and is emptied by two scum pumps.

Scum pump status is indicated below the pumps and by a colored circle on the pump symbol.

One pump may be selected as lead or both may be selected to run in the lead role.

The pumps may be selected to run automatically in response to time set points, scum box level set points or both.

On and off duration set points for timed operation may be adjusted from this screen.



6.7 Scum Box and Pumps Set Points This pop-up is opened by clicking the “level and pressure set points” button on the Scum Box screen.

It presents level control and alarm set points. Level is shown to the left with a vertical bar graph and two colored bars indicating pump operating ranges.



6.8 Scum Pump Pop Up

This pop-up is opened by clicking the status box for a scum pump. It allows selection of automatic or manual modes and start / stop control in manual mode.



6.9 Scum Box 2 and 3

Scum boxes 2 and 3 differ from the others in that there are two pumps shared between two scum boxes. If the level is above the start set point in either scum box (and level control is selected) pumps will be called to run.



6.10 Sludge Box and Pumps

This screen shows a sludge box and its associated pumps. Operating mode for the sludge pump system is displayed on and can be modified from the screen for any sludge box.

Status information, including speed and current is displayed for each pump. On duration may be adjusted from this screen as well.

Each pair of pumps has a flow transmitter. Instantaneous flow rate and totalized flow are displayed. The flow total may be reset. The target flow rate is adjustable and a loop view is launched by clicking the “Loop” button.

The operating mode for the pair of pumps is selected from the pushbuttons on the right of the screen.



6.11 Sludge Flow Control Loop

The flow control loop view pop up allows an operator to monitor control loop operation and to put the loop in manual mode, setting the speed command for the active pump.



6.12 Sludge Pump Pop Up

This pop up screen shows more detailed status information and allows an operator to control a pump.

In manual mode, the operator starts and stops the pump with the pushbuttons and sets the pump speed command directly.

If load shed is selected, the pump will not operate in automatic mode when utility power is not available.



6.13 Flow Transmitter Pop Up

Typical for new process value transmitters (as opposed to existing ones), clicking on the flow transmitter bubble will open a pop-up where alarm status can be viewed and alarm set points may be adjusted.

The bell symbol shows that alarms are currently enabled for this device. A “No” symbol will cover the bell when alarms are disabled.



6.14 Primary Tank Drainage / Recycle Pump Station

This screen shows the status of the tank drain pump station. Two submersible pumps are depicted with status information shown below and in the colored squares on the pump symbols.

Instantaneous and totalized recycle flows are shown in the upper right and an operator may reset the total flow from the “reset” button.

The pumps operate in a lead / lag scheme; role assignments are made using the pushbuttons in the lower right.



6.15 Primary Tank Drainage Set Points

Clicking the “level and flow set points” button on the Tank Drainage Pump Station screen opens this pop up.

Level control and alarm set points may be adjusted and the current level is shown to the left along with pump operating ranges.

A high recycle flow alarm set point may also be adjusted from this screen.



6.16 Primary Sludge Pump Summary This screen summarizes status information for the primary sludge pumps.

Clicking on the status line for an individual pump will open the pump control pop-up for that pump. Clicking on the flow rate indicator for a pump pair will open the screen for that pair of sludge pumps.



6.17 Secondary Sludge Pumping The secondary sludge pumps screen shows status for four sludge pumps. Clicking in the status box for a pump will launch a pop up identical to that depicted above for the primary sludge pumps.

Each secondary sludge pump has its own flow meter with totalizer.

Like the primary sludge pumps, the secondary pumps operate as a system in either continuous or cycle modes.



7 Sample Panel View (OIT) Screens Sample screens for local Panel view operator interface for the Primary Sedimentation system follow. This Panelview has a lot more screens, but these are the only ones that were changed significantly during the modifications of the existing PLC4 system. The secondary sludge screens are new and the primary sludge screens were modified.



7.1 Primary Sedimentation System Overview Screen

This is primary sedimentation system overview screen.



7.2 Sludge Box 1 and Pumps

This screen shows sludge box 1 and its associated pumps. Operating mode for the sludge pump system is displayed on and can be modified from the screen for any sludge box.

The operating mode for the pair of pumps is selected from the scroll-down menu on the right of the screen.



7.3 Sludge Box 2 and Pumps

Identical to the screen for sludge box 1, this screen presents sludge box 2 and its associated pumps. There are similar screens for sludge boxes 3 and 4.



7.4 Sludge Pumps 1-8 Set points

This is the sludge pumps 1-8 set point screen; an operator can adjust the sludge pumps running time and can select cyclic or continuous duty operation.



7.5 Secondary Sedimentation Tank

This sample screen shows secondary sedimentation Tank 1 and its associated pump. The operating mode for the sludge pump system is displayed on and can be modified.



7.6 Secondary Sludge Pumps Control

This is the secondary sludge pumps 1-4 set point screen; an operator can adjust the sludge pumps running time and can select cyclic or continuous duty operation.


Documents

PLC 4 PRIMARY SEDIMENTATION SYSTEM SCADA SYSTEM OPERATION … Primary... · 2013-10-08 · PLC4 – Primary Sedimentation System (Allen Bradley PLC5 - Main PLC Rack) Fig-1; PLC-4