Complexity of Grid-Connected Power Electronics Converters and Its Impacts on Modern Power Grids

Grid-connected power electronic converters play a vital role in integrating renewable energy sources into the power grid and enhancing the efficiency and flexibility of grid operations. However, due to their inherent nonlinear characteristics, these converters can introduce unexpected, diverse, and complex dynamic behaviors into the power system. Such behaviors may compromise normal grid operation and increase the risk of failures and blackouts, including voltage collapse, sub-synchronous oscillations, loss of synchronization, and frequency instability. The physical origins of these phenomena cannot be adequately captured using conventional linearization techniques, which typically neglect nonlinear terms and only provide insight into the stability of the nominal operating point. To address this limitation, this paper presents a comprehensive review of recent research on the complex dynamics of converter-based power systems. Topics include various routes to voltage instability through bifurcation sequences, transient stability enhancement via significant expansion of the stable basin of attraction, novel mechanisms for sub-synchronous oscillations involving hidden attractors, and frequency, voltage, and power fluctuations under the influence of distributed secondary control. Adopting this nonlinear perspective enables a deeper understanding of the fundamental mechanisms behind power system instabilities. It also supports the development of effective mitigation strategies to prevent blackouts and facilitates the integration of increasing levels of renewable energy and power electronic devices. As the penetration of power electronics continues to rise — alongside the adoption of inter-coupled control and communication technologies — the dynamic behavior of modern power grids is becoming increasingly complex. This complexity has profound implications for the reliable and efficient delivery of electrical power, underscoring the need for continued research in this evolving field.