Flexible AC Power Flow Control in Distribution Systems by Coordinated Control of Distributed Solar-PV and Battery Energy Storage Units

The flexible AC transmission systems (FACTS) have been used for controlling power flows in the transmission corridors to improve both the steady and dynamic states of operation. This paper proposes to extend the FACTS concept to power distribution systems, where the focus is in controlling renewable energy resources (RERs) and battery energy storage systems (BESSs) to provide a flexible AC power flow control in the distribution corridors of a medium voltage (MV) distribution system. The outputs of the proposed flexible AC power flow control system (FACPFCS) can be used to help the distribution network operator (DNO) to optimize the use of RERs and BESSs in the existing distribution grid to obtain the following benefits: congestion relief, sag reduction in long lines, mitigation of reverse power flow in the grid, deferral of distribution upgrade, Volt/VAr support, peak shaving, and a controllable storage bus that can act as a generator or load. To validate the proposed FACPFCS, simulation studies have been carried out using a practical radial distribution system topology derived from the electricity networks of New South Wales, Australia. The simulation results demonstrate that FACPFCS can provide an effective coordinated control of BESS and solar-PV units in the distribution systems to provide the mentioned benefits by controlling the power flows in the distribution lines.