Monday, 5 June 2023

Synchronized and Democratized (SYNDEM) Smart Grid Enabled by Virtual Synchronous Machines

Over the last few decades, there has been a substantial drive towards the reconfiguration of conventional power systems to accommodate a greater number of Distributed Generation (DG) units that harness renewable or non-polluting resources. This shift is attributed, in part, to the depletion of conventional energy sources and the growing public demand for environmental conservation. Most nations have acknowledged this trend and are investing heavily in exploring the potential of Distributed Energy Resources (DER). The increase in demand for energy, driven by technological advancements and the constant growth of the world's population, coupled with the need for reliable and safe power supplies, has prompted specialists to explore alternatives to the traditional power systems model. Moreover, the widespread energy crisis and frequent large-scale power outages have exposed the limitations of central power generation. As a result, there is a need to invest more in developing a reliable DG system that is financially viable, has a lesser environmental impact, and provides flexible power generation methods. The future of power systems appears to be a combination of distributed generation and centralized power generation methods.

The smart grid paradigm consists of a combination of conventional centralized generation and newer and more varied distributed generation. Due to the complex and dynamic nature of the DERs, the current control techniques have proven to be incapable of coping with the ever changing nature of the diversified loads and renewable energy resources such as Photo Voltaic (PV), Wind Turbines, Electric Vehicles (EV), and Battery Energy Storage Systems (BESS). Therefore, a revolutionizing and paradigm shifting control technique called Synchronized and Democratized (SYNDEM) soft architecture is introduced to address the challenges brought on by an ever more interdependent grid.

The SYNDEM grid architecture seeks to harmonize the integration of energy sources, storage systems, and flexible loads in a synchronized and democratized manner. This is achieved by operating power electronic converters in these sources and loads as Virtual Synchronous Machines (VSM). VSMs can be used to provide the necessary inertia and damping to power systems that conventional generators provide, thereby making them more resilient. The proposed method internalizes the model of a Synchronous Machine (SM), to virtually achieve the behavior of machine inertia, damping, and self-synchronizing in a way that is simpler to tune and customize. The resulting system, comprising the inverter/rectifier, filter inductors and capacitors, and the associated controller, is referred to as a synchronverter. By adopting the synchronverter concept, the inverter can provide the same level of stability and performance as a synchronous generator while leveraging the benefits of power electronics, such as flexible operation and high efficiency.  The goal of this project is to construct, simulate, and comprehend a SYNDEM smart grid.

The project successfully designed and modeled the SYNDEM smart grid using Matlab/Simulink and presented the simulation results, including successes like the implementation of MPPT for solar, and challenges encountered like the incomplete integration of a realistic wind turbine. Through the application of VSMs to three different DERs and a flexible load, the SYNDEM paradigm has been explored, and the benefits of VSMs have been showcased.  The simulation scenarios analyzed demonstrated the behavior of the systems under different conditions and loads, providing insight into real and reactive power flows, frequency response via droop modes, and regulation of DC bus voltages. The results showed that the frequency oscillation was inherent to the single-phase VSM designs used, and the inertia of the DERs was tuned to reduce this oscillation. In the simulations, the VSMs have been shown to operate in tandem on the microgrid scale, while participating in grid reliability through droop response and providing virtual inertia.  Autonomous operation was demonstrated as well, as the VSMs did not require inter-communication to achieve stability.  The VSMs also properly self-synchronized, without the need for an external PLL.  Overall, the project demonstrated the successful implementation and operation of a variety of devices via the synchronverter concept.



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