“We have three physical servers instead of nine, six CPUs instead of 18, and 24 cores instead of 72.” Gaston Llamas of YPF on one of the many benefits the Argentine refiner realized through control system virtualization.
"In July 2009, the Argentina government modified the law," explained Llamas. "The most important change was a new standardization for fuels." Law No. 17.319 Hydrocarbon Law—Resolution 478/09 2/6/2009 specifies timeframes for new value compliance of low sulfur content for fuels to be supplied to the Argentina market.
"Compliance to this requirement resulted in the need for control system modernization," said Llamas. "Refining is a continuous process. Uninterruptible operations are a key factor. Unexpected stops may result in damage to people, the environment and installations and loss of production."
YPF needed a control system modernization strategy that would allow them keep up with the latest technologies as well as ensure availability of the DCS. ABB’s System 800xA was chosen as the control system, and the accompanying IT infrastructure was virtualized with VMware.
The architecture needed to be double- or triple-redundant, depending on the criticality of the unit. "A simple modification of our system would not have been enough," said Llamas. "We needed a radical change. We decided to use a triple-redundant, geographically distributed virtualized 800xA system. We used three physical servers, which we call hosts. Each host virtualizes one domain controller, one aspect server and one connectivity server. Virtual switches are created to communicate to the virtual machines. And the virtual switches have physical Ethernet ports to communicate with the virtual machines located on other hosts."
Requirements for the network architecture included the ring topology between server locations, central control room operations and connection to the control system from the engineering room. At first, the virtual architecture was introduced, but the original architecture remained operational, sharing the network infrastructure. The two systems were kept isolated using VLANs. Once control logic was redesigned in accordance with the new standards, it was added to the virtual infrastructure and the old physical servers were removed.
Virtualization reduced the number of servers, cut down on project costs, decreased the number of needed spare parts and standardized hardware. It also increased control system availability by ensuring proper operation even under hardware degradation. The amount of time needed for hardware exchange or modernization also was reduced. And system flexibility increased because the addition and testing of new nodes became easier. Virtualization also reduced energy consumption and heat dissipation of IT equipment, improved security by controlling access to hardware and reduced the time for factory acceptance tests.
"Factory acceptance tests are a key factor for us," said Llamas. "With virtualization, we can test the hardware independently from the software. Standard tests include correct deployment of virtualization software, hard-drive redundancy configuration, power and network redundancy and VMware vCenter configuration."
Design guideline manuals were developed jointly by ABB and YPF. To ensure the same functionality and look and feel across all systems, standards were created for system configuration, logic programming and human-machine interface design.
"With virtualization, we have three physical servers instead of nine, we have six CPUs instead of 18, and we have 24 cores instead of 72," said Llamas. "While the networking hardware cost is the same—$44,000—server hardware costs are $45,000 for virtualized, half of the cost of a traditional system. We realized a 63% power consumption savings in the virtual system, too."
