The impact of renewable energy installations connected to the utility grid is an important
issue concerning the technical and economic viability of harnessing these emerging
energy sources. Distribution networks must be carefully controlled in order to
maintain an acceptable power supply quality. The major sources of non-conventional
energy are small scale generation and storage from mini hydro, photovoltaic, wind
power, fuel cells, battery, flywheel, pump storage and biomass.
The aim of this thesis is to analyse the variation in voltage of the distribution network
when renewable energy sources are interconnected to the distribution network, in
terms of it's stability. In particular this study analyses the impact of interconnection of
small synchronous generators to the utility power grid. Dynamic stability analysis is
mainly concerned with analysing the response of electrical power system to small perturbation
about a given operating point. These studies are particularly important due
to the growing interest in interconnecting small renewable energy sources to large and
complex power systems. Simulation studies were carried out in order to find out the
transient stability and voltage stability of the non-conventional energy sources under
different operating conditions. A 5-second simulation was conducted using explicit
numerical integration (Euler method) and an integration time step of 0.002 second.
Power System Toolbox was used for analysis.The multimachine power system models
used in this thesis are generated in MATLAB code. The load flow is performed on the
multimachine power system correponding to the loading condition to be investigated.
The machines are represented by the two-axis models, the exciters by IEEE Type-1
models and the loads are modelled as constant impedances. To save programming
time, it has become common to limit the machine and exciter representations to some
specified models. The network admittance matrix is reduced by retaining only the internal buses of the generators. The reduced network, machine and exciter data are then
combined to form a linearised state-space model representing the entire system.
The simulation studies are applied to a four machine ten bus system. It is clear from
the analysis that much care should be taken based on the stability point of view while
interconnecting the small renewable energy sources to the utility. The renewable
energy sources should be interconnected at a point which provides higher stability
margin.The renewable energy sources is a viable option if it is connected to the
distribution network with necessary methods of improving transient stability and
voltage stability.