On the Implementation of OPF Based Setpoints for Active Distribution Networks

In the context of active distribution networks, AC Optimal Power Flow (OPF) has shown great potential to calcu-late setpoints for controllable devices. Although considerable literature exists, temporal aspects that may affect the actual exe-cution of these setpoints are rarely investigated. Due to the di-verse operating characteristics of controllable devices (i.e., de-lays, ramp rates and deadbands), when these setpoints are exe-cuted by multiple devices without adequate considerations, the resulting outcome can differ drastically from what is expected; leading to violations of network constraints and excessive control actions. Therefore, this work proposes a series of necessary adap-tations within the controllers of existing devices as well as in the OPF formulation to cater for the diversity in operating charac-teristics, ensuring that calculated setpoints are adequately im-plemented by controllable devices. This involves the direct con-trol of conventional devices and enforcing a new ramping behav-ior for inverter-interfaced devices. Furthermore, a linear, mixed-integer formulation is proposed to handle discrete devices and improve scalability in large networks. Co-simulation results (us-ing a UK test network with the objective of maximizing renewa-ble energy production and considering 1s time-step) demonstrate that, by catering for the operating characteristics of controllable devices, the expected outcome from OPF-based setpoints can be achieved.