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Industrial Ethernet Book Issue 98 / 13
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Predictive maintenance strategy for energy substation computers

Substations are becoming "digital substation automation solutions" fueled by computer technology that gives operators an ability to digitize substation operations and leverage communication interfaces to address the substation′s primary equipment, resulting in more effective monitoring and control.

COMPUTERS PLAY A PIVOTAL ROLE in today′s power substations. The role of computers in a substation has expanded from merely providing computing power to more critical roles such as analyzing, monitoring and controlling substation processes.

Today, computers are used extensively in the bay and station levels of an IEC 61850 substation to manage and control IEDs such as protection relays, PMUs, merging units, fault recorders, and GOOSE/SMV analyzers, as well as for environmental monitoring and surveillance.

Any computer-related performance issue or failure has the potential to directly impact the operation of a substation or disrupt the power distribution system. Therefore, the reliability and availability of substation computers is a key factor for the efficient operation of a substation, making it essential that substation computers be managed on par with the other critical equipment in the substation.


Centralized proactive remote alert solution for a group of substations.

Why use predictive maintenance?

The three typical approaches to maintaining equipment (including computers) in a power substation are:

Reactive maintenance (breakdown or run-to-failure maintenance) In this case, equipment continues to run until it fails. Repairs or replacements of damaged equipment are only undertaken after a problem occurs. Although some substations use this approach, it is not recommended for critical substation equipment such as computers.

Preventive maintenance (time-based maintenance) Maintenance activities are scheduled at predetermined time intervals. Computers benefit immensely from time-based maintenance rather than run-to-failure maintenance.

For example, some studies have shown that by adopting a predictive maintenance program over reactive maintenance, users can save anywhere between 12% and 18% on cost. However, preventive maintenance has some drawbacks:

  • If a computer malfunctions before the predetermined maintenance time, the outcome is similar to run-to-failure maintenance.
  • Time-based maintenance sometimes involves performance of needless maintenance activities.
  • Time-based maintenance can be labor intensive.


Condition-based maintenance

Maintenance activities are scheduled when warranted by mechanical or operational conditions based on periodic monitoring of the equipment and observing unhealthy trends that occur over time. As a result, damaged equipment is replaced before obvious problems occur. Predictive maintenance can deliver 8% to 12% cost savings over preventive maintenance.

It should come as no surprise then that the trend today is towards computer maintenance strategies that are based on predictive maintenance. Substation computers are now categorized as "critical equipment" in substations and are included in the predictive maintenance program for substations.

Many substation operators and system integrators also include computer-related requirements in their tender specifications. For example, CPU loading of computers that are used in substation processing and communication, and memory usage requirements of computers are now an integral part of tenders for substation computers.

A fully functional predictive maintenance strategy works very well if personnel have adequate knowledge, skills, and time to perform the predictive maintenance work. This type of strategy allows equipment repairs to be scheduled in an orderly fashion and provides some lead time to purchase materials for the necessary repairs, thereby reducing the need for maintaining an inventory of key parts.

Since maintenance work is only performed when it is needed, the production capacity is likely to increase as well. Although adopting a predictive maintenance program requires an initial investment in diagnostic equipment and software, as well as staff training, the benefits quickly outweigh the costs. This maintenance approach is by far the best strategy for critical substation equipment that includes computers.


Proactive monitoring utilizes hardware sensors in the computer′s motherboard to monitor key parts of the computer.

Predictive maintenance

Most computers today come with built-in hardware monitoring tools either at the BIOS level or as part of the operating system.

BIOS hardware monitoring: Most components inside a modern PC include sensors that can monitor parameters like temperature, power consumption, and fan speeds. One way to read these values is with a BIOS hardware monitor. However, you can only access the BIOS when the computer boots up.

Performance monitoring: The limited performance monitoring functions provided by Windows and Linux, which usually only include the system temperature and a few other parameters, may not be enough for designing a predictive maintenance strategy for substation computers.

The key to a good predictive maintenance solution is to use the BIOS hardware monitor and the OS performance monitoring tools in the computer to get the status of the key parts and use a tool to continuously monitor these values. Users should be able to define threshold values for the key parts of a computer and closely monitor the key parts based on these values. If a key-part value goes over a threshold, the system should be configured to automatically trigger alerts.

However, most solutions available in the market today can only monitor the system temperature and a few other parameters, which is not enough to define a comprehensive predictive maintenance strategy for substation computers. Furthermore, many systems do not provide the ability for users to define threshold values for computer key parts and may also lack an alert function.

If your substation has a predictive maintenance system in place, an easier strategy is to use existing monitoring utilities to procure the readings of key parts for the computer and feed this data to an existing predictive maintenance system in the substation, so the system can generate alerts based on thresholds set for these key parts.


Centralized proactive remote alert solution for a substation.

Predictive maintenance technology

A predictive maintenance solution called Proactive Self-Maintenance from Moxa, consists of a proactive monitoring utility and a centralized proactive remote alert solution.

Proactive Monitoring offers a small-footprint, resource-friendly, easy-to-use utility that allows you to track a number of system parameters. Proactive Monitoring utilizes the hardware sensors in the Moxa computer′s motherboard to monitor the key parts of the computer. You can view the current parameter values for these key parts by simply clicking on the icons corresponding to the parameters in the user interface. User-defined key part indicators (KPIs) are used to monitor the computer′s key parts. Visible and/ or audio alerts are triggered automatically via relay and SNMP traps when these KPIs go over their preset threshold values, making it extremely convenient for operators to avoid system downtime by setting up predictive maintenance tasks well in advance.

A ready-to-use centralized proactive remote alert solution can provide these benefits:

  • Centralized visible/audible alerts to the control room via the Ethernet
  • No relay output needed on the computer
  • No cabling constraints
  • Combined SNMP traps to detect system errors faster and accurately

Summary

Substation systems are evolving into digital substation automation solutions. This is fueled by advancements in information technology that provide operators with the ability to digitize substation operation, extend communication interfaces to the substation′s primary equipment, and monitor and control the substations more effectively.

Computers play a key role in the success of digital substation automation solutions, and a good maintenance strategy can help increase the lifespan of these computers. The trend in computer maintenance in substations is increasingly towards predictive maintenance (also known as condition-based maintenance). A well-orchestrated predictive maintenance plan can support the maintenance needs of a substation computer well ahead of time, thereby optimizing the uptime and reliability of the computer and saving on maintenance costs.

Daniel Lai is a Product Manager at Moxa, Inc.


Source: Industrial Ethernet Book Issue 98 / 13
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