IEC 61850 standard-based protection of the coupling point between a wind farm and the power grid

Abstract

Power system aims to continuously supply power to customers even at very high demand. The high energy demand causes a decrease in voltages at the substations and this may cause the voltage collapse in the power system, which in turn may cause a total system shutdown if not attended to. Since the increased load demand becomes a major cause of voltage collapse in power systems, additional power sources, namely wind power plants are of recommendation and this is due to their reactive power contribution to the power systems. Wind power plants improve the reliability of the power system by supplying power to the grid when load demand is too high, while at the same time withstanding some of the natural power system disturbances, namely short-circuit faults and sudden increase in load demand. Power quality is one of the power system requirements when integrating wind power plants into the existing power grid. The general wind power plant operational mode is that a wind generator should be disconnected from the grid when its output voltage goes below or above by ten percent from its rated voltage. Due to uncontrollable wind speed, wind generators produce fluctuating power leading to the tripping off of the generating unit. The fluctuating power from the wind generators appears on the grid side, reducing the reliability of the existing protective devices set for the system. This thesis makes use of the IEEE Nine-Bus system modelled and simulated using the Real-time Simulation Computer-Aided Design (RSCAD) whose simulations are in real-time with the support of the Real-Time Digital Simulator (RTDS). Using the simulated power system network, contingency studies are conducted in terms of the load demand increase to calculate the additional power requirements. A wind power plant (WPP) is also modelled using the same modelling and simulation platform and coupled into the power system in compensation of the additional load demand. Most importantly, the IEC 61850 standard-based protection scheme is developed for the coupling point of a wind power plant to the power. This protection scheme is adaptive for both load conditions of the system when the wind power plant is coupled into the power system.