Dynamic Stability Analysis in Distribution Networks with Dynamic Loads and Renewable Energy Sources

The main focus of this thesis is the modelling, control and stability analysis ofdistribution networks with distributed generators and dynamic loads in which thedynamic loading effects in standard distribution networks are taken into consideration. Different case studies are considered, such as fault effects, a worst-casescenario and nodal voltage analyses of different network configurations. The dynamic modelling includes line resistance, which has been neglected in the existingliterature, but which the case studies show is a critical parameter affecting systemstability. An LQR controller is proposed for minimising the effect of resistance inthe distribution network. A novel linear zero dynamic controller (LZDC) is designto maintain the voltage and angle stability for distributed generators. Some elementary notions for the LZDC are introduced such as relative degree, Lie derivativeand exact linearization. This thesis also presents a new concept of a multiple inputmultiple output (MIMO) LZDC for a three-phase grid-connected photovoltaic (PV)system to enhance its stability and robustness under different weather conditions.Grid-connected PV systems are highly nonlinear systems in which most of the non-linearities occur due to the intermittency of sunlight and the switching functions oftheir converters and inverters. The proposed controller overcomes the limitations ofother controllers, such as the PI, hysteresis, predictive and sliding-mode controllers,and it is proven that this system operates at unity power factor. The effectiveness ofthe proposed control strategies are demonstrated through time-domain simulationstudies conducted using the standard industry-based software environment