Implementing the Internet-of-Things (IoT) to Extend the Useful Life of Smart Grid T&D Assets

By Femi Ayankogbe

In light of the growing concerns over the aging of transmission and distribution (T&D) power system assets, which complement smart grid applications , there is an increasing need to find innovative ways of extending asset useful life. Thus, asset investment planning (AIP), capital expenditure (CAPEX) and asset replacement decisions can be put off safely into the future, without introducing additional operational risks and without jeopardizing asset performance and electric grid network reliability. Implementing an IoT solution can assist in achieving this objective. Historical equipment sensor data can be used to predict the failure profile of critical assets, in order to apply in time intervention measures, which will prolong the average time to failure.

Proactively managing the useful life of smart grid assets has become a necessary process, given aging infrastructure, cost pressures from energy regulators and the increasing power demand from consumers, who continue to purchase and own more electronic gadgets and personal devices per capita. Optimizing necessary maintenance costs without jeopardizing grid reliability and environment, health & safety processes (including the health & safety of field operations and maintenance personnel), can only be achieved, if the machine state and condition of critical grid assets are known at all times. This requires attaching intelligent sensors to these assets, to monitor their operating conditions & operating factors in near real-time intervals and on-demand.

The suggestion is to introduce an IoT smart grid platform, which helps to capture and analyze sensor data in order to drive advanced asset maintenance strategies like Condition-based Maintenance, Reliability-centered Maintenance and Predictive Maintenance (PdM). An IoT platform solution can provide tangible benefits in support of these strategic and operational asset management objectives. It can be deployed to extend equipment useful life by capturing, translating and consolidating condition data from SCADA, Substation Intelligent Electronic Devices and other equipment sensors (e.g. Transformers & Circuit Breakers) to aid in the development and delivery of:

1. Real-time Asset Health Indexes

2. Predictive Maintenance Tools

3. Human Deployment / Dispatch systems for early maintenance intervention and remedial activities

A recent example of such a solution was that of an Electric Utility that was able to perform Transformer intervention and repairs (for one hundred thousand dollars), based on the analysis of trending Dissolved Gas Analysis (DGA) sensor data, and prevented a catastrophic failure of a Substation transformer. In doing so, a $2m capital expense was avoided, in addition to an eighteen-month waiting time for a replacement transformer to be designed, transported and installed.

An IoT-enabled Digital Utility Platform solution is an IT/OT integration platform that records and consolidates time-series data from Substation Transformers & Circuit Breakers to support the development of:

• Real-time Transformer and Circuit Breaker Health Dashboards that show RAG statuses and trending graphs from the equipment’s operating condition data streams
• A PdM Tool that drives a Maintenance Management System to schedule preventive maintenance or inspection work actions, if and when transformer or breaker operating parameters are outside tolerance limits (e.g. transformer oil temperature or dissolved gas analysis readings)

The Digital Utility Platform (DUP) also transforms the asset condition time-series data into an online in-memory analytics database platform to analyze historical asset operating data and extrapolate an Equipment Failure Probability profile using predictive algorithms such as the Weibull distribution.

Asset Criticality should be the initial focus of an IoT-enabled DUP in the smart grid, so that assets connected to large commercial and industrial (C&I) customers or major residential zones are monitored more closely.

The criticality of such smart grid assets can be determined by one of the following criteria:

1. The Lead Time required to replace the asset (e.g. In most cases, the transformer procurement cycle has a lead time of up to 18 months – in the case of High Voltage Substation Transformers – to be designed, manufactured and delivered.)

2. The Replacement Cost of the asset (e.g. Large Power Transformers can cost millions of dollars, depending on their Capacity Rating.)

3. The asset’s electrical connectivity to critical C&I customers (e.g. A major manufacturer or an upstream oil & gas facility, where production downtime costs are in the vicinity of millions of dollars per day.)

4. The asset’s connectivity to feeder(s) that supply power from major zone substations to densely-populated residential areas.

Technology Stack of the IoT Solution

The digital utility platform solution that proactively manages critical smart grid assets, in order to prolong their useful life, comprises of 6 major components:

1. Intelligent sensors for Transformers and Breakers – typical operating factors monitored include DGA, Voltage, Oil Temperature, Moisture and SF6 Gas discharge.

2. IP-compliant and security-hardened Data Acquisition systems that are smarter iterations of SCADA and RTUs.

3. Data Consolidation systems that can handle the volume, variety and speed of time-series machine operating data.

4. Data Transformation tools to translate IoT sensor “Big Data” into relational data models using a structured in-memory analytics database.

5. Enterprise Asset Management or Computerized Maintenance Management Systems that can receive the appropriate “out-of-tolerance” Machine Notifications in order to trigger Preventive Maintenance and Inspection work action requests.

6. GIS-enabled Intelligent Scheduling and Mobile Dispatch Tools to assign to the appropriate mobile field-service workers and crews for maintenance intervention at the relevant asset locations, based on their skills, safety/electrical certifications (e.g. lockout/tagout), availability and proximity.

In summary, an aging infrastructure environment need not cause stress and concerns to smart grid investment planners and network operators. The IoT promise can deliver tangible benefits in keeping the smart grid resilient and reliable. This is achievable by using predictive analytics from IoT-enabled platforms to extend the useful life of critical T&D assets and postpone expensive capital investment, while managing operational risks and preserving asset performance and safety.

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