Vulnerability Assessment of Modern Power Systems: Voltage Stability and System Strength Perspectives

Climate change is one of the most dangerous and simultaneously most complex threats humanity has ever faced. The key response to this threat has been an unprecedented strategic shift in the energy sector, known as the energy transition. Electricity powers the modern world and is at the very centre of the energy transition. The shift to sustainable electricity production, transmission, distribution, and consumption is therefore vital. However, such a change brings significant technical challenges that should be addressed. The objective of this research is to uncover and investigate some of the key challenges in this regard and propose solutions for their mitigation.

This thesis largely focuses on two technical aspects and related challenges: power system vulnerability and stability. The emphasis lies on modern power systems, where conventional synchronous generation is increasingly replaced by inverter-based resources (IBRs). The first research objective is to improve the understanding of both system vulnerability and stability, particularly in the context of voltage stability and system strength and their intricate relationship. Relying on this improved understanding, the second objective is to develop advanced and novel evaluation methods and algorithms.

The developed methods form a basis for advanced voltage stability and system strength evaluation of modern power systems. Such an evaluation can play an important role in the overall stability and dynamic security assessment performed by power system operators, with the goal of cutting through the complexity of numerous possible contingencies and operating scenarios. The evaluation automatically identifies the most vulnerable weak grid sections and dangerous operating scenarios that may lead to cascading faults and possible instability. Consequently, once such grid sections and scenarios are observed, more detailed simulations and analyses can be performed by power system stability experts in a much more time-efficient and targeted manner. Subsequently, proactive mitigation measures can be taken to avoid the risk of instability and blackouts.