Bikash Pal


Optimal Fault Ride Through Voltage Support of IBR-Dominated Power Systems

With the increasing penetration of inverter-based resources (IBRs), disconnecting IBRs from the system “at first sign of trouble” could exacerbate system instability under large voltage disturbances (sag, swell and unbalance). Several large blackouts or interruption events in relation to the improper operation of IBRs under voltage disturbances have been reported in recent years. Although a consensus has been reached that IBRs should be able to ride through various voltage disturbances while providing dynamic voltage support (DVS) to the grid, it is still not clear how to achieve the optimal DVS. This talk will share our recent research efforts in improving the DVS performance of IBRs under abnormal voltage conditions. Three critical questions are answered via optimisation. 1) What is the maximum DVS capability of a single IBR? 2) How to implement the maximum DVS without relying on the knowledge of grid model parameters? 3) How do multiple IBRs interact with each other in a network? The optimisation-based methodologies open up an effective way to explore sophisticated control strategies of IBRs under large disturbances, and the research findings complement and even challenge our physical intuition.

Stability Modelling and Analysis of Converter Driven Power System

The number of power electronics converters connected to electrical networks has been growing exponentially as they are part of all new generation connected to the grid. While the rapid control and fast electronic switching available with this technology offer flexibility in network operation, the dynamic interactions between several of them threaten the operational stability of the transmission grid is a concern. It is required to develop a methodology for identifying the risks associated with the stability and control interaction before a new power electronic device (e.g. Windfarm, interconnector, STATCOM) is introduced to the network.

The talk will focus on an analytical framework in impedance domain to quantify the interaction between the new plant and the rest of the network for setting additional grid connection study specifications which will include detail technical study to check and mitigate the risks associated with new power electronics interfaced generation. The framework developed is to support MMC technology, control delay, system strength and FRT capability of dynamic voltage support devices and windfarm through technical case study conducted at the research group of Bikash Pal at Imperial College London. Future research challenges and opportunities will be highlighted.

Robust Volt-Var Control in Power Distribution

Electrical generation, transmission and distribution systems all over the world have entered a period of significant renewal and technological change. There have been phenomenal changes/deployments in technology of generation driven by the worldwide emphasis on energy from wind and solar as a sustainable solution to our energy need. Increasingly energy demand from heating and transportation are being met by electricity. These changes have significantly influenced the planning, design, operation and control of the power distribution system. Accommodating uncertainties in renewable generation and demand forecast in a cost-effective manner is now a very complex optimization problem. This talk will share our recent research efforts Volt/VAr control (VVC) strategy in distribution systems to address the uncertainties. Efficient chance constrained conic optimisation technique accelerated through scenario reduction approach will be discussed to demonstrate the significant reduction of voltage violations when compared with the deterministic cases while not relaxing the conservativeness of the final solutions. It will also touch upon treatment of certain types of load characteristic in the proposed solution framework. Future research challenges and opportunities will be highlighted.

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