Management of Active Distribution Networks with High Penetration of Distributed Generation

Abstract

The penetration of distributed generation and wind power in particular is expected to increase significantly over the coming years, and a huge shift in control, operation and planning of distribution networks is going to be necessary if this generation is to be connected in a cost effective manner. Traditionally, distribution networks have been operated as passive networks with uni-directional power flows and were designed through deterministic (load flow) studies considering the critical cases so that distribution networks could operate with a minimum amount of control. With the connection of increasing amounts of distributed generation, these networks are becoming active and with power flowing in the two directions, hence requiring more intelligent forms of management. Increasing connection of intermittent distributed generation, such as wind power, to distribution networks requires new control strategies to provide greater flexibility and use of existing network assets. Active network management (ANM) will play a major role in this and will help in facilitating connection of new generation without the need for traditional reinforcements. This thesis is based on a multi-period AC optimal power flow (OPF)-based technique for evaluating the maximum capacity of new intermittent distributed generation able to be connected to a distribution network when ANM control strategies are in place. The ANM schemes embedded into the OPF include coordinated voltage control, adaptive power factor, energy curtailment and demand side management. A generic U.K. medium voltage distribution network is analyzed using coincident demand and wind availability data derived from hourly time-series. Results clearly show that very high penetration levels of new variable generation capacity can be achieved by considering ANM strategies compared to the widely used passive operation (i.e., “fit and forget”). It has been shown that with coordinated voltage control (CVC) there will be a positive impact on minimizing the losses in a distribution network compared with old passive operation by around 20%. Also active network management (ANM) can result in reducing the total average voltage deviation. The thesis has founded that the DG installed capacity can be increased by active network schemes to some extent in case of load growth.