Utility Power Transformers’ Performance Enhancement in Smart Grids
Power Transformers (PT) are one of the most critical components of a Transmission & Distribution (T & D) Utility in terms of its impact on network availability. Apart from criticality, it is one of the costliest equipment in a substation comprising up to 60% of total investment. Multiple operational and environmental factors such as overloading, moisture, heat, progressive ageing, and so on lead to deterioration of insulation (winding and bushing), oil quality and so on result in decreasing PT operational efficiency and lifespan. It is crucial to assess the health condition of such PTs continuously to realize improved efficiency, early fault detection & diagnostics, prediction of maintenance requirements, and reinvestment strategy. The solution is developed to monitor and predict the performance of PT. Data Historian/Cloud Platform acts as a data lake and model repository to fetch online parameters and offline test results integrating with multiple data sources such as SCADA, online Dissolved Gas Analyzer device, Bushing monitor and the Enterprise Resource Planning (ERP) system. Asset Health Index (AHI) for PT is calculated using a multi-criteria analysis approach to derive a quantifiable figure which represents the condition based health of the PT. AHI calculation not only considers online parameters such as DGA, Load, Bushing tan delta capacitance, but also the offline test results such as power factor, Degree of Polymerization, Polarization Index, Winding Resistance and so on. Duval Triangle and IEC Ratio techniques employed in the solution for detecting the incipient fault and diagnosing nature (thermal/electrical) and location (paper/oil) of fault when it occurs. The deployed solution can help the Utilities in: (1) Adopting condition based maintenance strategy moving away from schedule based maintenance; (2) preventing unwanted breakdowns; and (3) Prioritize planning to achieve optimal balance between maintenance and replacement strategy. This paper discusses about the challenges faced by the Utilities in managing the PTs, which has crossed significant life span and the solution to resolve the challenges, taking into consideration maintenance practice followed in Utilities, availability of measurement/test data in Utilities and recommendations of international standards.
KeywordsPower transformer Asset performance management Asset health index Duval triangle IEC ratio DGA
The authors would like to show their gratitude to Dr. Krishna Prasad, Mr. Manish Singh and Mr. Mangesh Pawar for their valuable support and guidance in completing the work.
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