Decentralized voltage control coordination of on-load tap changer transformers, distributed generation units and flexible loads

The increase of distributed generation is expected to generate instabilities, such as power imbalances or voltage deviations in the power system. At the distribution level, maintaining the bus voltages within the stipulated limits is one of the major challenges for the distribution system operator. Under low penetration levels, several voltage regulation elements have been efficiently employed up to now. However, under large distributed generation levels, the traditional techniques have to be coordinated with new upcoming solutions, such us demand response. In this paper a simple and decentralized approach is introduced in order to coordinate the voltage control capability from different assets in medium voltage networks. In this sense, the on-load tap changer strategy of the primary substation and the power factor control of wind turbines and combined heat and power plants are combined with the power factor control of the existing Power-to-Gas facilities. The feasibility of the coordination strategy is tested in a benchmark medium voltage network. The results show that the voltage magnitude is kept within the stipulated boundaries when applying the proposed approach, making limited use of the on-load tap changer and the reactive power from dispersed generation while maximizing the capacity usage of the Power-to-Gas load.