Virtual Plant Best Practices for Virtualization in Process Automation
Virtual worlds have until now mainly been known from the field of computer games. But through information technology, they have also found their way into industrial automation. What are the opportunities and risks of a production plant in a virtual environment and how can virtualization solutions be implemented?
The concept of virtualization has its origin in the world of information technology (IT) and describes the emulation of hardware, operating systems, data storage and networks. It helps to distribute computer resources more purposefully, to combine them clearly, or to run virtual operating systems within a host operating system.
The IT world is developing rapidly — driven by increasingly complex software that requires more and more hardware resources. This means the number of computers is constantly growing, which in turn results in higher expenses for administration, space and service. A typical example is a company computing center which manages hundreds of computers. Another dimension of the complexity is caused by different life cycles and hardware versions (PC technology), operating systems such as Windows NT, XP or 7, as well as the wide range of application software. This situation made it easy for the innovative technology of virtualization to take a hold. It not only optimizes administration, space and service, but it also makes for more efficient use of resources such as CPU, memory and storage space and ultimately results in cost savings.
Virtualization: The Impact of the IT Revolution on the Process Industry
This expanding IT world in companies has increasingly penetrated the domain of industrial automation — with the objective of passing along the benefits and, in particular, the cost savings to the production world.
Production plants are under particular pressure to lower costs and demand low investment expenditure, fast commissioning and optimal operation without production downtimes.
A virtualization solution starts with higher IT investment for host systems, virtualization software, maintenance contracts, and possibly also for cooling, air conditioning and noise control for the high-performance host systems. This investment usually pays off during the life of the plant. Companies implementing virtualization solutions typically have dedicated IT departments with highly trained specialists. Special knowledge of process automation is also required, as demonstrated by the following two examples:
- Functions commonly used in the IT world, such as moving applications in runtime for the purpose of load distribution (vMotion) or pausing a client or server (suspending), cannot be easily carried over to the production environment.
- When high-availability servers are operated in a virtual environment, certain aspects of availability must be taken into consideration. Redundant servers should run on different host systems, such as different computers or blades, to prevent “single points of failure”.
There is no catch-all answer to the question of when virtualization makes sense or becomes efficient. The specific requirements of the project always determine the required approach. There are aspects such as space requirements, remote access, energy savings, validation, and distribution of the plant; but also the existing infrastructure, or the operation of other applications in a virtual environment such as analysis utilities as well as information and reporting systems.
Virtualization with Simatic PCS 7
The following virtualization solutions are possible with Simatic PCS 7:
- Approved functions: Operator Station (OS), Batch, Route Control clients and a variety of options such as visualization of sequential control systems, PCS 7 Web server, OpenPCS 7/OS client, PCS 7 terminal server.
- Functions approved for specific projects: all servers (OS, Batch, Route Control) engineering system, OS single station.
- Other functions have been successfully operated as prototypes in a virtual environment.
Thin clients or zero clients connected by remote protocols such as VNC or VMware View are integrated as operator stations, in other words, front-end PCs. The operator finds a familiar user environment in this case.
Overview of Systems for Plant Virtualization
Systems that are well established in the market are recommended for implementation of the virtualization solution. Some of these have been tested with Simatic PCS 7:
- Host systems such as: Industrial PC rack systems from Siemens; rack systems from Fujitsu, Dell; blade systems from HP, Fujitsu, Dell.
- Hypervisor (virtual environment): e.g., vSphere or vSphere Hypervisor (ESXi) from VMware.
The topic of security/IT security also plays an important role in the field of virtualization. The same mechanisms and methods as in the real world environment apply here, such as security patches, virus scanners, user management and access control to the system. There is an added layer, the hypervisor layer (such as vSphere Hypervisor from VMware ), in which the appropriate security aspects have to be taken into account.
Prominent Examples and Best Practices
Industries such as food & beverages, pharmaceuticals, chemicals and water management have already begun to deal with the topic. The implementation can be considered in more detail with specific, prominent examples from some of these industries.
The pharmaceutical industry is driven by its variety of products and the resulting frequent product changes, which require a great deal of coordination between the IT world and production. One particular aspect is the subject of validation. Whereas in the past the initial investment for a validated system included a few computers as spare parts, today, these costs as well as those for the corresponding storage space can be saved through hardware virtualization. What is different here:
- Servers (for OS and Batch), which would be formed by separate server pairs in a real world environment, are distributed over two separate host systems for reasons of availability.
- Access from the virtual office environment to virtual long-term archives and reporting systems is provided by Web mechanisms.
- Administration costs are reduced through consistent expansion of the IT infrastructure with regard to virtualization, from the office to the production plant.
There is a lot of pressure on costs in the area of water management, particularly in the operation of the plants by municipalities. The aspect of plant distribution is also a factor, not only in terms of geography, but also hierarchy for remote access of regional and district centers to central waterworks. The special considerations here are:
- consolidation of the entire control system server infrastructure in one data center;
- flexible access to a virtual Web server by up to 50 Web clients;
- optimized plant operation through the implementation of the PCS 7 operator concept: access rights for clients in the main control room, the higher-level regional and district centers and local panels;
- interaction between clients in the control room (virtual world) and local panels (real world);
- cost savings by using the IT infrastructure of the data center.
The aspect of remote access also plays a role in the chemical industry, e.g. in “unmanned” air separation plants, which are remotely monitored and operated from a central control room. The special features here are:
- compact, economical and energy-saving design of the individual plants each in a virtual environment;
- secure monitoring of numerous plants from the central remote operation center (ROC) by means of a remote protocol on the individual (unmanned) plants;
- local availability of all control system functions when work is performed on site.
Real vs Virtual Plant – Benefits and Risks
Virtualization is an innovative technology used to implement user requirements in modern control system structures. However, it is not a panacea and it cannot be used effectively in all environments and in all situations. The most important requirements for operating a process control system in a virtual environment are a good IT infrastructure and suitably trained personnel.
This means that although the initial investment is higher, only project-specific benefits are gained in the short term. In the long run, however, the investment pays off in many cases over the life cycle of the plant due to reduced operating costs. The mechanisms of the real world have to be transferred carefully to the virtual environment, because a real plant is running with real consequences in the background.
In short, today’s answer to the question is not “real or virtual,” but rather “real and virtual”.