System Redundancy in Substation Retrofits
The Trend in Power Substation Automation
In order to reduce power outage occurrences and duration, power grids around the world are increasingly retrofitting legacy power substations to automate control, data acquisition, and supervision. The trend in substation automation has been moving towards collecting and integrating the data from all of IEDs and subsystems into a powerful and secure control system that can serve as a platform for device monitoring today and advanced diagnostic systems in the future.
The Importance of Management-System Redundancy
Since replacing existing legacy power substations with newly-built automated facilities is generally impractical and cost-prohibitive, most substation automation applications rely on retrofitting or upgrading legacy equipment and integrating the relevant subsystems. Due to the mission-critical nature of power substation applications, management system redundancy is of the utmost importance when retrofitting legacy substations equipment and subsystems especially in remote and unmanned control, data acquisition and supervision. Moreover, paying special attention to management-system redundancy when retrofitting for power substation automation can help you to minimize system downtime and allocate more resources to troubleshooting.
Control and Management Issues
When retrofitting a power substation, system integrators need to overcome a number of control and management pain points. First, when an unstable application crashes on a system, system errors will not only affect the application crashed, but may also hang the entire system and affect other applications running on the same computer.
Second, control and management issues can also arise when migrating legacy applications. For example, many legacy substation applications were originally designed for older OS versions by a third-party vendor who may no longer be providing support for the original application to the end-user. As a result, simply upgrading the firmware may not be enough, or even feasible, to migrate these custom-built software applications for use with the latest operating systems and hardware. Oftentimes, end-users may even need to commission a new application to be developed for the new OS.
How Management-System Redundancy Resolves Management Issues
System redundancy in power substation retrofitting applications can be achieved using either decentralized or centralized system management architectures.
In a decentralized management architecture, system redundancy is ensured by multiple physical computers where each computer only runs a single operating system and application. Since each computer on a decentralized system is only running a single application, an unstable application on any node represents a single point of failure in this multi-node network. These are clear benefits to running multiple operating systems and multiple applications on the same physical server.
But to deploy one physical machine for each application, this hardware-based approach will clearly incur additional equipment and maintenance overhead.
Moreover, a decentralized management architecture may not overcome the issues associated with migrating legacy applications, due to the fact that new computer platforms usually do not support drivers for legacy operating systems.
In a centralized management architecture, on the other hand, system management redundancy is achieved by running multiple operating systems and applications on the same physical server via virtualization technology (i.e., VMware). By running multiple operating systems and multiple applications on the same physical server, virtualization lets you reduce costs while increasing the efficiency and utilization of your existing x86 hardware.
First, instead of physically isolating applications on separate computers, server virtualization provides application isolation and removes application compatibility issues by consolidating many of these virtual machines across far fewer physical servers.
Second, integrated availability and fault tolerance protects all your virtualized applications. If a server or node ever fails, all the virtual machines (VM) will automatically restart or continue on another machine, with no downtime or data loss.
Finally, by virtualizing and encapsulating legacy applications, you can effectively extend the life of the legacy application, maintain system uptime, and finally replace ageing and out-dated equipment on your network with the latest hardware.
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