Optimal Deployment of Reactive Support From Renewable Energy Sources for Voltage Regulation in the Prospective Transmission Network of Serbia

Participation of renewable energy sources (RES) in voltage regulation in the transmission grid when voltage values at the 400 kV transmission grid nodes exceed the maximum permissible limits, the participation of renewable energy sources (RES) in voltage regulation requires the optimization of reactive power flows to minimize the need for reactive power absorption from the transmission network, thereby reducing the costs associated with the absorbed reactive energy. Optimizing reactive power flows also minimizes active power losses in the transmission network. This paper presents optimization algorithms that operate by sending an array/sequence of voltage setpoints to the regulators of all RES units to minimize active power losses and the amount of reactive power absorbed from the transmission grid. The application of these algorithms will be demonstrated using the Serbian transmission network as a case study for a future scenario that anticipates intensive integration of wind power plants (WPP) and photovoltaic power plants (PVPP), totaling 7100 MW of WPP and 3500 MW of PVPP. The calculations will be performed using DIgSILENT PowerFactory software.