LRWRP_Design_Report_Chapter_9.pdf

CHAPTER 9

INSTRUMENTATION AND CONTROL SYSTEM (TM 7)

Introduction

9.1.1 Project Background

The LRWRP was constructed in the mid-1970s, and much of the electrical, instrumentation, and controls in place at the LRWRP reflect the technology in use a t that time.

Brown and Caldwell has reviewed the electrical and instrumentation upgrades described in the City's 2002 Master Plan. In addition, a project electrical, instrumentation and controls meeting was held on September 29,2004 with the City of Lompoc Public Works Department staff to discuss the proposed WWTP upgrade project. A copy of the meeting minutes is included in Appendix A.

9.1.2 Objectives

This Chapter documents the proposed instrumentation and control system for the LRWRP. The instrumentation and control systems required to meet the process requirements in a reliable and cost effective manner are identified and recommended.

i i As outlined in the scope of work for this project and as discussed at the instrumentation and controls meeting, the evaluations and recommendations for the following topics are addressed in this Chapter:

Field Instrumentation Control Room Instrumentation Networking SCADA Architecture PLC/SCADA Programming Instrumentation Power Supply Recommended Improvements and Costs

Evaluation of Instrumentation and Controls Requirements

9.2.1 Field Instrumentation

The existing field measuring instruments are almost 30 years old and past their useful life.

Replacement parts on these instruments are often not available since microprocessor based smart instruments have replaced all the old fashioned instruments.

Brown and Caldwell recommends replacing all the old existing field measuring instruments by the latest microprocessor based instruments. All other new instruments to be procured shall be of the

, same manufacturer for the same type of instruments to reduce the needed spare parts inventories.

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Instrumentation and Control System (TM 7) 9-2

Unless otherwise required, instrument transmitters shall have analog direct current signal output of the 4-20 mil range with 2-wire transmission.

9.2.2 Control Room Instrumentation

Most of the existing control room instruments are almost 30 years old and are in need of replacement including: multiplexer type control system, circular strip chart recorders, indicators, hardwired graphic panels, etc. Replacement parts on these instruments are often not available since microprocessor based smart instruments have replaced all the old fashioned instruments.

Brown and Caldwell recommends replacing all the old existing panel mounted type measuring instruments by a PLC based SCADA system with HMI Workstations in the administration building as well as in other selected process areas including, but not limited to, influent building, coagulation/filtration area and disinfection area.

9.2.3 Networking

Figure 9.2.1 presents the proposed SCADA network diagram. Fiber Optic Ethernet LAN shall be implemented with PLCs connected to the LAN through fiber optic type converters.

The PLC control network and SCADA information network will be physically isolated and both will be in a self-healing fiber optic ring configuration.

A wireless system could be provided to provide access to the SCADA system from any point in the plant. Since there will be workstations and network jacks installed throughout the plant, it does not appear that a wireless system is required and is not recommended at this time. However, wireless will be considered for remote locations like flow metering vaults.

The SCADA information network jacks will be installed in areas where future workstations may be installed including, but not limited to, administration offices, blower building and digester building.

9.2.4 SCADA Architecture

9.2.4.1 General. This section gives an overview of the proposed LRWRP instrumentation and control system. The Central Control System HMI Workstations located at the administration building control room will provide monitoring, supervisory controls and reporting for all the areas.

The new SCADA system will monitor and control all sipficant variables in accordance with the process requirements, and provide all operating requirements and necessary safety controls including alarms for off-normal conditions. The SCADA system shall be designed to carry out the control and monitoring functions of various process parameters of the plant. The functions to be carried out by the system shall include indication of control and non-control process parameters; manipulation of

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SECONDARY CLARIFIERS

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ABBREVIATIONS:

F.O. FIBER OPTIC CABLE

HMI HUMAN-MACHINE INTERFACE (WONDERWARE)

TEL TELEPHONE CABLE

FOC FIBER OPTIC CONVERTER

FOP FIBER OPTIC TERMINATION PANEL

OIP OPERATOR INTERFACE PANEL

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GENERATOR BUILDING AND

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FLOW EQUALIZATION TANK

CHEMICAL FACILITIES AND

TERTIARY CLARIFIERS

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INFLUENT PUMP

STATION AND

OXIDATION DITCHES

DAFT AND GRIT

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UV DISINFECTION

EFFLUENT FILTERS

AND EFFLUENT PS

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ETHERNET &-- CO. TELE.fi MODEM

INFORMATION NETWORK

ETHERNET SWITCH ETHERNET SWITCH

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B R O W N AND AT FULL SIZE- ,.- ..-.-,.-

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LOMPOC REGIONAL WASTE WATER

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INSTRUMENTATION

FIG. 9.2.1.

PROPOSED SCADA

NETWORK DIAGRAM

PROJECT NUMBER

DRAW~NG NUMBER

SHEET NUMBER

M N 0 P

Instrumentation and Control Svstem C I M 7) control loops including set point, mode and output; graphic recording of real time trends and historical trends of the variables;, alarm l o g p g and display; totalizing; tabular log display of process variables; and dynamic process mimic diagrams on the HMI.

The system shall be capable of displaying a number of types of displays on the HMI. These are overview display, group display, detail display, and trend display. The over view display shall represent the equivalent to front view of a control panel. The group displays shall represent the equivalent of a bank of instruments. Each display shall be identified by a number and title and the points shall be identified by their tag name. Any point in the system shall be able to be configured in any group and displayed in as many groups as necessary. At the group display level the operator shall be able to select a control loop or point for control action, and/or select a loop and initiate further displays such as detail display, trend display, etc. The detail display shall represent a view of a single loop. The operator shall be able to call up any point in the system on the detail display. The trend display shall graph current/historical trend information for a single or a number of loops on a variable time basis. The display shall be continuously updated with current values.

When the SCADA system detects an alarm, the alarm message wiU be displayed at the HMI and the alarm log will be available to print on the printer upon an operator request. The operator will confirm the alarm and respond by requesting an alarm summary display and acknowledging the alarm. An alarm acknowledgement message will then be printed on the alarm event printer. All the alarms also will be remotely transmitted to the on-call operator to his telephone as voice alarm via autodialer software.

There are three options available for accessing data remotely. The method of remote access connection should be determined by weighmg such factors as security, speed, reliability, and flexibility. The options are shown below and the pros and cons of each method are discussed.

9.2.4.1.1 Option 1: Remote Control Using PC Anywhere Via Internet. This option requires that PC Anywhere be installed on a server machme and on the client machines that will be accessing the server remotely. PC Anywhere can be configured on each machine such that the server will only allow connections from specific IP addresses, if using static IP addresses, or username and passwords, if using dynamic IP addresses. Using this method, the remote client machine will be able to connect, and take control of, the server machine at a typically high access speed.

Pros: Broadband access to server machine.

Cons: High security risk. Hackers are more likely to invade a TCP/IP based network than a dial-up network.

9.2.4.1.2 Option 2: Remote Control Using PC Anywhere Via Dial-up Connection.

This option requires that PC Anywhere be installed on a server machine and on the client machines that will be accessing the server remotely. Using this method, the remote client machine can take remote control of the server machine, albeit at a much slower connection speed than with an internet connection. For added security, the server machme can be configured so that the client machine dials-in to make a connection request. The server will then call the client machine back using a known safe phone number.

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Instrumentation and Control System (TM 7) 9-5

Pros: Much safer than internet access. The line-in side of the modem can be wired through an on/off switch so that the server can only be accessed when needed. Otherwise the server is physically impenetrable from the outside.

Cons: Slow connection speed. Disruptions in phone connection could result in loss of signal, requiring the client machme to redial.

9.2.4.1.3 Option 3: Remote Access Using a Virtual Private Network Via Dial-up Connection. This option does not require any addtional remote access software provided that the client machine and server machine are running Windows XP (Home or Professional editions). Using this method, the client machine will dial-in to the server machine and connect to the control network using a VPN connection. Assuming Wonderware is the selected SCADA software, the client machine must have Wonderware Intouch installed. Using this method, the client machine becomes a Wonderware Intouch client node and accesses data remotely from the 1 1 0 server machines.

Pros: Much faster access speeds, despite dial-up connection. The line-in side of the modem can be wired through an on/off switch so that the server can only be accessed when needed. Otherwise the server is physically impenetrable from the outside. Client can also have access to control network for file transfers.

Cons: Client machine must have Wonderware Intouch installed.

Dial-up connection stdl not as fast as broadband.

Option 3 is the recommended solution for remote access to the proposed network.

9.2.4.1 General. The SCADA architecture will be reviewed by the City's IS department during final design. Access to SCADA screens will be limited to authorized users via several levels of password protection.

Tracking of by whom and when changes occur in the SCADA software can be done by ualizing the SCADA software data logger, which will track the username and'date stamp of every operator action.

The SCADA software shall include report writing capabilities via Microsoft Industrial Sequel Server and Excel. The type of reports will be defined in the control strategies during design and programmed by the selected SCADA programmer.

All data will be archived by the SCADA system utilizing the RAID 5 hard drive system, which will include several hard drives each backing up one another. The City will need to implement a system for backing up the hard drives on CD or DVD periodically (every 6 months or yearly), to assure the hard drive does not get overloaded.

The actual control of individual areas will be performed by an individual process area Programmable Logic Controller (PLC). The recommended manufacturers in the water and wastewater industry are Allen-Bradley or Modicon. Both of these manufacturers have a sufficient installed base to ensure development and support for a twenty year expected life.

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Instrumentation and Control Svstem fT'M 71

The new HMI workstations will be running the SCADA HMI software, which will allow operators to monitor instruments, controls, equipment status and alarms, and record data and graph it on historical trend charts on the monitor. The operator interface will have the ability to record instrument data to be viewed later in graphic form (i.e., historical trending). The following are the most common SCADA HMI manufacturers in the waterlwastewater industry:

, Wonderware "Intouch" Allen Bradley "RSView" GE-Intellution "iFix" US Data "Factory Link" National Instruments "Lookout"

Of these the recommended manufacturer is Wonderware based on the following criteria:

Ease of use.

Open software architecture.

Well supported in California.

Sufficient installed base to ensure development and support for a twenty year expected life.

9.2.4.2 Control Modes. During design, the control modes for each process area will be analyzed and coordinated with the City's O&M staff.

Three control modes will be implemented for equipment control:

Automatic PLC (selected at HMI) Manual PLC (selected at and controlled from HMI) Local (selected at and controlled from individual piece of equipment)

9.2.4.3 Remote Control (at HMI). When the Local-Remote switch at a piece of equipment is in the Remote position, the operator can select between two modes of operation a t the HMI, Automatic PLC and Manual PLC. In Automatic PLC mode, the equipment is controlled by the PLC, according to the control strategies. In Manual PLC mode, the operator can manually control equipment from the HMI.

9.2.4.4 Local Control (at individual pieces of equipment). When the Local-Remote switch at a piece of equipment is in the local position, the operator can control the equipment locally. Local control has priority over remote (i.e., PLC) control; when in Local mode, commands from the PLC w d have no effect.

9.2.4.5 Interlocks. Software interlocks will be provided on some equipment through the PLC. For example, a pump may not be allowed to start until the PLC senses that the pump discharge valve is open.

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Instrumentation and Control Svstem (TM 7)

These interlocks will be in effect in both Automatic PLC and Manual PLC mode. These PLC interlocks will not be in effect when controlling equipment locally, although there are some cases where hard-wired interlocks will be in effect in all three modes.

9.2.4.6 Alarm Management. In general, when a field alarm occurs, the alarm is latched in software.

For safety reasons, the associated device will not be restarted until the alarm is eliminated. In order for the alarm to be acknowledged and cleared, two events must occur: the field condition creating the alarm must be corrected, and the alarm must be acknowledged by the operator at the appropriate location.

9.2.5 PLC/SCADA Programming

Detailed control strategies will be developed during design for the selected PLC/SCADA programmer. There are two recommended options for selecting the programming delivery method.

Option one is the traditional method of the contractor being assigned the task of subcontracting to a systems integrator to provide the PLC and SCADA programming. The second option is to assign the design consultant the task of PLC and SCADA programming. The advantages of the second option are the following:

Interpretation of the control strategies does not become a contractual issue.

The design consultant can provide superior training since the City would be a part of programming team.

Changes to HMI screens based on O&M input during the programming task do not become a contractual issue.

Regardless of who does the PLC/SCADA programming, the contractor or the design consultant, the City will be trained in and have full licensed control of the SCADA software and the PLC software to make modifications after this contract.

9.2.6 Instrumentation Power Supply

The Central Control System and the field mounted PLC cabinets and HMI workstations will be provided with separate, uninterruptible power supplies (UPS) to insure uninterrupted control operation. Each UPS wdl be sized for a 30-minute ride through time at 50% load.

Recommendations

9.3.1 Recommended Improvements

This section summarizes recommended improvements for the plant instrumentation and control system to provide an efficient and cost effective way to manage the overalJ plant instrumentation and control system.

Replace the existing field instruments.

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Instrumentation and Control System (TM 7) 9-8

Remove all the existing control room instruments including wall mounted serni-graphic mimic panels.

Provide a new PLC based SCADA system utilizing a fiber optic type Ethernet based networking system.

9.3.2 Preliminary Construction Cost

The preliminary estimate of probable construction cost for instrumentation and control systems is $1,977,040 as indicated for TM 07 in Table 2.1-2.

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