Diagramming Bulk Electrical Power Flows: Portraying Aggregate Compass Directionality, Vector Field Representations and Recirculating Loop Structures

Modern transmission networks span entire continents and operate under conditions of growing variability, making it increasingly difficult to summarise and interpret their behaviour. Conventional tools such as one-line diagrams and geographic flow maps provide detail but often become cluttered, obscuring the dominant features of grid operation. This thesis develops three complementary visualisation approaches that address this gap by focusing on directionality, recurring patterns, and structural inefficiencies in power flows. First, radial glyphs are introduced to aggregate thousands of line flows into concise compass-based summaries, allowing prevailing transfer directions to be recognised at a glance. Second, vector-field abstractions are proposed through hexagonal tessellations and streamline diagrams, which reveal seasonal and event-driven flow regimes across Europe by combining spatial simplification with clustering of representative states. Third, loop flows are diagnosed by integrating network-theoretic measures of recirculation, including strongly connected components, feedback-arc sets, and the Fath–Borrett Cycling Index, with Sankey-style diagrams that make hidden circulation explicit. Applied to both synthetic test systems and continental-scale European data, these methods demonstrate how visualisation can reduce complexity while highlighting essential features: dominant transfer corridors, recurring directional states, and inefficiencies due to cyclic exchanges. Collectively, the contributions show that carefully designed visual abstractions extend the analytical toolkit available to grid operators, planners, and researchers, offering clearer ways to interpret and communicate the dynamics of highly interconnected power systems.