Voltage control in MV distribution networks through coordinated control of tap changers and renewable energy sources

The significant penetration of renewable energy sources (RES), like wind and solar power plants, into distribution networks has changed their operation considerably and brought new challenges for distributed system operators (DSOs). One of the main problems associated with high penetration of variable RES into distribution networks is voltage rise problem along the radial distribution feeders, with high production variability causing frequent operations of the onload tap changers (OLTC), thereby causing significant deterioration of their operation life expectancy. This paper proposes new method for the Volt Var control in the MV distribution network with the high share of RES relative to the distribution system load. The problem is casted as the mixedinteger nonlinear programming (MINLP) problem associated with the voltage control in the distribution network with the objective to maximize daily RES production and through reactive power control to minimize the daily distribution system losses using the Benders´ decomposition method. In order to reduce the number of OLTC switching operations, the time instances in which the change is possible are set a priori. The effectiveness of the proposed method is tested on well-known IEEE 69-bus system.