Dynamic phasor modelling and simulation of power networks with converter-tied renewable resources
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Abstract
Due to the massive integration of renewable energy generation in modern power systems, the dynamic characteristics of the power grid are rapidly changing. Spurred by device limitations and the wide range of controls present in converter-based generation, the resulting reduction in system inertia and system strength warrant improved modelling methods that provide analytical insight into the operation of modern power systems. Conventional approaches for analysing transient and small-signal stability are being challenged due to the new, non-linear controls present in converter-based generation. Due to their inability to represent the network dynamics, conventional phasor-based methods are no longer suited for detailed studies in converter-based systems. Electromagnetic transient (EMT) based methods successfully capture the dynamic characteristics of such systems but are restricted in terms of their capability to provide analytical insight using formal means such as eigenvalues. This thesis proposes a modelling approach based on average-value, positive-sequence dynamic phasors, that can integrate transient simulation and small-signal studies into a singular modelling platform. A component based modular approach to develop the model of a large power system is presented and is benchmarked against EMT and conventional phasors demonstrating its accuracy on par with EMT simulations, while also providing analytical insight through eigenvalue analysis. The proposed modelling method is parallelized using graphics processing units (GPUs) providing significant performance gains over EMT simulations. A limitation of the proposed modeling method, which arises with networks with all inductor nodes, is addressed using a novel method that allows both transient responses and eigenvalue analyses with a significant reduction in model order. Finally, an example case is studied determining the operational parameters for grid-following and grid-forming converters for stable operation. Based on both eigenvalue analysis and transient responses, this is analysed for a single machine infinite bus (SMIB) system for a case with reducing short circuit strength and a case of network strengthening through series compensation.