Background:
Since the distribution networks are passive until Distributed Generation
(DG) is not being installed into them, the stability issues occur in the distribution system after the
integration of DG.
Methods:
In order to assure the simplicity during the calculations, many approximations have been
proposed for finding the system’s parameters i.e. Voltage, active and reactive powers and load angle,
more efficiently and accurately. This research presents an algorithm for finding the Norton’s
equivalent model of distribution system with DG, considering from receiving end. Norton’s model
of distribution system can be determined either from its complete configuration or through an
algorithm using system’s voltage and current profiles. The algorithm involves the determination of
derivative of apparent power against the current (dS/dIL) of the system.
Results:
This work also verifies the accuracy of proposed algorithm according to the relative variations
in the phase angle of system’s impedance. This research also considers the varying states of
distribution system due to switching in and out of DG and therefore Norton’s model needs to be updated
accordingly.
Conclusion:
The efficacy of the proposed algorithm is verified through MATLAB simulation results
under two scenarios, (i) normal condition and (ii) faulty condition. During normal condition, the stability
factor near to 1 and change in dS/dIL was near to 0 while during fault condition, the stability
factor was higher than 1 and the value of dS/dIL was away from 0.
A Two-layer Multistage Expansion Planning Method for Adaptability Enhancement of Distribution Networks