Optimum Voltage Droop Control to Support Local Voltage Stability in Transmission Systems with High Share of RES

Abstract

In this thesis, I designed a voltage droop control method for the high share of RES connected to the electrical transmission system. The control of voltage profile in transmission system is becoming very complicated with the high amount of RES connected to the VHV substation. Also, the reactive power management needs to be ensured in the VHV/HV substation not only in the point of interconnection but also for the individual wind power plant and photo-voltaic plant. Based on the real case study provided by the Portuguese National Transmission system operator named Redes Energeticas Nacionais (REN), this thesis provides a new voltage droop control strategy for avoiding conflicting set point of each wind power plant and photo-voltaic power plant connected to the transmission system. Before coming up with a final solution that mitigates the voltage fluctuations at the point of interconnection that utilizes the voltage regulation capabilities, different scenarios were analysed and simulated. The main aim of this thesis was to come up with a control strategy in which the voltage will be in its steady-state limits in all the plants which will be examined.