Autonomous Voltage Control Strategies in Distribution Grids with Photovoltaic Systems

This thesis analyzes the technical and economic potential of autonomous voltage control strategies for improving distribution grid operation with high shares of photovoltaic (PV) generation. Key issues include:

1. The simultaneity of local photovoltaic generation and local consumption as well as its influence on reverse power flows. 2. The theoretical potential of autonomous voltage control strategies to increase a grid’s hosting capacity for additional photovoltaic generation. 3. Stability analyses of a voltage-dependent combined active and reactive power control strategy for photovoltaic inverters. 4. The cost savings potential (CAPEX & OPEX) of autonomous voltage control strategies, compared to traditional grid reinforcement measures. The results suggest that autonomous voltage control strategies can be used to improve the technical and economic distribution grid integration of PV systems. If applied appropriately, these strategies are capable of deferring grid reinforcement measures and hence shifting investment costs to future points in time. Of all investigated autonomous voltage control strategies, the on-load tap changer voltage control and a combined Q(V)/P(V) PV inverter control strategy showed the most promising results, from a technical and an economic perspective.