Tapan Saha


Operational Challenges of High Renewable Dominated Grid and Some Perspective

When a power system is dominated by variable renewable energy generators (e.g. solar and wind) to meet CO2 reduction targets, fossil fuel based synchronous machines are expected to be retired from the network. The high penetration of renewables and the removal of synchronous machines imposes some challenges of maintaining the adequate level of system strength and inertia. Synchronous condensers, battery storage and pumped hydro storage are capable of strengthening the power system security against credible contingencies. This presentation will cover some of our recent research findings and will also provide a general perspective.

Impact of High Solar PV Penetrations on Distribution Network

Rooftop solar PV penetration in the Australian distribution network has increased exponentially over the last ten years. This is also evident in many other countries. This brings some challenges for the utilities and customers, which include bidirectional power flow, less inertial generation and unregulated/intermittent behaviours. Most small scale PV systems are integrated at a power distribution level, and distribution networks have never been balanced due to asymmetrical upstream sources, non-transposed lines and uneven phase loads, thus analysis of PV integration impacts should take network imbalance into account. In steady states, unbalanced loads and PV power have unequal contributions to voltage drops of each phase. Moreover, during cloud coverage phases of unbalanced networks have different voltage variation sensitivities to PV power swings. Therefore, it is possible that an unbalanced network may suffer over voltage and unacceptable voltage imbalance at certain buses. This seminar will highlight these voltage problems of PV integration into an unbalanced distribution network and will highlight some of our recent works with possible solutions using distribution system state estimation and dynamic operating envelope applications.

Transformer Condition Monitoring and Diagnosis of Moisture and Ageing to Estimate the Remaining Life

Large proportions of power transformers in many countries are currently operating beyond their design lives. Many classical diagnostic techniques are currently in practice by utility engineers to monitor their conditions. Among them Dissolved Gas Analysis (DGA), Degree of Polymerisation (DP) and furan analysis by the High Performance Liquid Chromatography (HPLC) are commonly in use. Many standards (IEC, IEEE and ASTM) are available to interpret the ageing and moisture conditions of transformers. This tutorial will first outline detailed ageing analysis of insulation materials and drawbacks of using commonly available diagnosis techniques for the assessment of transformer ageing conditions. A number of new intelligent based diagnostics have been investigated and implemented by the speaker’s research group, which includes High Frequency Current Transformer based online PD measurements, online moisture analysis by capacitive sensors & Polarisation/Depolarisation Current Measurements. This tutorial will highlight these state-of-the-art diagnostic techniques and remaining life assessment methodologies for power transformers using the newly developed tools. A number of new diagnostic tools with machine learning algorithms and expert systems have been further developed by the speaker’s research team, which will be also outlined in details in this tutorial with a number of case studies.

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