Superior Controls implemented a $250k Cogeneration Plant Control System that integrates the balance of plant functions. The system consists of a single Emerson DeltaV node with redundant processors. This control rack contains direct wire digital and analog I/O modules to integrate various Balance of Plant points within the facility.
The system also interfaces devices over Fieldbus within the plant and the interface to serial data through Modbus RTU protocol. An Allen-Bradley ControlLogix was used as a gateway which includes Ethernet interface modules and Prosoft MVI56-MCM Modbus RTU interface modules. The gateway exchanges data between the various vendor equipment controllers through the Ethernet interface. The data exchanged between the DeltaV system and the various PLCs are compacted into contiguous Modbus register locations for efficient communications to the DeltaV systems over Modbus RTU communications. Communications from the DeltaV controller to the Building Automation System and the Electrical Distribution System is direct through Modbus RTU serial communications and does not pass through the gateway.
The DeltaV control system is implemented on three stations inside the plant control room. The operator station is the primary application of the DeltaV Operate environment and is the primary operator interface station. The engineering workstation is the ProfessionalPlus station and is used for systems engineering tasks such as DeltaV Explorer, tuning, and system configuration. The ProfessionalPlus station contains the development database for the entire DeltaV system. The engineering workstation also serves as a secondary DeltaV Operator interface station. The application station serves as the DeltaV Continuous Historian server and DeltaV OPC Pager server.
The Cogeneration Plant DeltaV control system network is separate from the site campus DeltaV system. System status overview screens are configured in the Process History View functionality of the Continuous Historian giving users outside the cogeneration plant DeltaV system access to information about plant operation.
The PCS provides the following main process control functions:
- Centralized control
- Consistent operator interface screens
- Alarm handling functionality
- Security management for the plant
- Fuel oil and natural gas usage metering with periodic reports
- Electrical and steam utility monitoring
- Integration of Continuous Historian with specific overview screens configured
- Field and Skid Components
The following list details the major system components which are controlled by and interface to the PCS:
- Combustion Turbine Generator
- Heat Recovery Steam Generator (HRSG)
- Duct Burner
- Auxiliary Boilers #1 and #2
- Water Treatment System
- Continuous Emissions Monitoring System
- Ammonia System