The architecture of the system (see diagram DG-INT-I&C-001_rv1) will be composed of three levels:
A higher supervision level will be installed in the Control Room of the WTP. Therefore, it will be out of scope of this document.
An intermediate process-control level composed of a rack with communication switches managing a fibre optic ring.
A lower field level composed of a redundant programmable logic controllers (PLC) in the Electrical Building of the Intake and four remote stations (RIO, Remote Input and Output included in the RTUs) to connect the digital and analogue inputs and outputs installed in the Isolation Manholes of the Raw Water Pipeline .
The communications networks between the different components of the system will be:
Between the communication rack in the WTP Control Room and the supervision system, communications will be via Ethernet protocol, based on a physical support of a cat-6A UTP cable. Therefore, it will be out of scope of this document.
Between the communication racks in the WTP Control Room and the automation equipment, PLCs and remote stations, communications will via Ethernet protocol, based on a fibre optic physical support, in a ring configuration.
1.2 General description
All the control points are associated to Remote Terminal Units (RTU). Moreover, all the Remote Terminal Units are connected to Main Terminal Units (MTU), main control points, by means of a fibre optic network, as follows:
The first requirement for the Intake and Pipeline system is an effective control system with a SCADA system that controls all the structure.
This control system must be supported on a communications system that links all control points and transmits all data between all sites.
1.3 Telecommunication system
The project requires the implementation of a Data Network, a Telephony System (VoIP), Security System (CCTV, Access Control) over a distributed IP Architecture for the WTP, the Intake and the Raw Water Pipeline.
The best scheme for the proposed system is an IP based solution that allows a global management from the security and communication point of view. It will be proposed an Ethernet Network over a single-mode fibre optic. The switches of the fibre optic ring will have PoE ports in order to deliver the power for the VoIP telephones. The switches will be DIN rail mounted.
All of these subsystems must be controlled from the WTP Control Room and the requirements of the equipment installed in the Intake and Raw Water Pipeline should comply the specifications of the equipment installed in the Water Treatment Plant.
1.4 Fibre optic ring
The fibre optic ring will controlled from the Water Treatment Plant and it will be configured according the equipment installed in the WTP Control Room.
Fibre optic rings will be configured with 210% of the fibres required, to provide the ability to upgrade the system resilience and add further functional networks.
In the Raw Water Pipeline, the fibre optic ring will be installed in ducts, each branch in a different pipeline trench to ensure simultaneous damage cannot easily occur.
The fibre optic will be a Single-mode fibre to ensure the communication between the Isolation Manholes and the WTP. Therefore, a 1550 nm wavelength fibre optic cable will be selected.
1.5 Control System
The control system is based on a SCADA with a PLC (Programmable Logic Controller) on each main control point.
The SCADA system is a group of databases with real time managers that manage all the control system. The software for SCADA is a standard pack programmable and customizable. The SCADA system is located at the Water Treatment Plant, and fulfils the main control system function, and they can be called Main Terminal Unit (MTU). The MTU controls all RTU (Remote Terminal Unit). The RTU, in this case, is a modular PLC that includes inputs and outputs (analogue and digital) modules to reach the instruments and variables control.
The control on this project is based on PLC. Each control point is equipped with a PLC with a CPU, RAM and ROM memory and Ethernet port for communications.
The modular PLC on each site includes input and output modules for controlling sensors signals and actuations on instruments. The number of inputs and outputs depends on the number and type of sensors and instrument actuators.