Research Projects

Electricity landscape is undergoing a major churn today & shifting towards a compositional form that is clean and sustainable. Traditional grid assets based on fossil-fuel-driven electromechanical synchronous generators, widely known to act as voltage-frequency masters in the grid, are increasingly being retired. This is accompanied by integration of greater percentages of power electronic inverter-based resources (IBRs), which are typically driven by renewable and storage energy resources. The existing technology for inverter integration, which adopts the grid-following (GFL) control regime, is deemed inadequate for large-scale integration of distributed renewable energy resources. The so-called grid-forming (GFM) inverter regime is an emerging next-generation paradigm that shows great promise for large-scale renewable integration by replacing traditional electro-mechanical assets, given its innate ability to act as voltage-frequency masters in the grid. There is wide recognition across industry & academia (in India & abroad) that GFM technology is the pathway towards the aspirational future grid. In this backdrop, different facets pertaining to the power electronic inverter, viz. hardware & control architectures, must also evolve. Focussing on the GFM inverters & their control regimes, three flavours of control exist today---Droop, virtual synchronous machine (VSM), and virtual oscillator control (VOC). While droop control has existed for at least two decades, VSM and VOC are relatively newer incarnations developed recently for fitting into the emerging GFM paradigm. The VSM regime innately carries inertia attribute, while droop & VOC do not carry this capability and thus, cannot offer inertial behavior as a feature. But, with the integration of battery energy storage to the inverter, inertia emulation is feasible for GFM inverters. There is a clear recognition that the state-of-the-art for GFM inverters as a technology, is in a state of flux & continuously evolving. Several open problems exist in both the control and hardware layers of the GFM inverter, that calls for immediate attention and critical examination via analytical as well as implementational lenses. Keeping these in mind, a Universal Grid-forming Inverter Power Electronics & its Control, is proposed as the overall strategy and means for advancing sustainability. It comprises a sufficiently generalized/universal hardware & control architecture, such that such that the system is capable of providing the key operational functionalities anticipated from the GFM inverter, which include (a) frequency & voltage regulation via bidirectional power flow, (b) inertia emulation via battery bank, (c) renewable integration via Solar PV front end. To that end, selected challenges & research problems (with near- and long-term impacts) at both hardware and control layers have been chosen and formulated into two major research thrusts---(a) modelling & simulation, and (b) hardware realization.