Assessment of Bus Inertia to Enhance Dynamic Flexibility of Hybrid Power Systems with Renewable Energy Integration

The integration of renewable energy resources (RES) and employment of multi-terminal dc links have dramatically transformed the structure of traditional power systems into hybrid networks with reduced inertia levels. Therefore, the new paradigm requires a coherent architecture for computing the spatiotemporal distribution of total system inertia. With this objective in mind, a novel approach is proposed in this paper for calculating bus inertia that captures power system dynamics and facilitates real-time computation of grid flexibility. The bus inertia is defined as the distribution of total inertia across all system buses located in different geographical regions. In this context, a simplified mathematical formulation for bus inertia computation is developed that does not require a linearized model for hybrid power systems. In the existing methods, linearizing whole power grid is complex, computationally challenging, requires mathematical modification for any change in systems and not rigid enough in terms of accuracy. The computation of bus inertia assists in identifying spatial system strength for any area or zone. Consequently, the proposed method may be utilized to meet the increasing penetration levels of RES and enhance grid flexibility. The computed bus inertia (and eventually system inertia) can also be applied for load shifting, allocation of wide-area damping controllers (WADCs), coherency detection, relay setting, sitting of RES and energy storage systems (ESS) to ensure stable and flexible operation of the power grids. The efficacy of the proposed method is tested using the two-areas, four machines test system, IEEE 39 bus, 68 bus and 118 bus test systems.