Biomedical Engineering Reference
In-Depth Information
Introduction
The load flow of distribution system is different from that of transmission system
because of their high R/X ratio and radial topology. Convergence of load flow is
utmost important. Matrix-based iterative methods do not lead themselves for radial
distribution system owing to their poor performance under critical conditions and
heavily loading conditions. A survey of literature shows that several methods for
distribution system load flow have been proposed [ 1 - 3 ]. However, all these
methods fail to obtain a solution in many instances because of matrices. Large
RDS have complicated structure and are subjected to changes in their topology
frequently for load balancing, maintenance, emergency operations under the
umbrella of Supervisory Control and Data Acquisition (SCADA), SCADA
requires a fast and reliable distribution load flow algorithm that computes the
voltage solution very rapidly.
To overcome the limitations of these regularly used methods a simple and
reliable ladder iterative technique is used for solving the power balance equations
of radial distribution system (RDS) that is, ladder iterative technique is described
for solving the radial system power balance equation treating every lateral and sub
lateral line as an individual main line [ 4 ]. This method utilizes forward sweep and
backward algorithm based on Kirchoff's current law (KCL) and Kirchoff's voltage
law (KVL) for evaluating the bus voltage magnitude and angles iteratively. The
computation of branch current depends only on the current injected at the
neighboring node and the current in the adjacent branch. This approach starts from
end nodes of sub lateral line, lateral line, and main line and moves toward the root
node during branch current evaluation (Fig. 2 ). The node voltage calculation
begins from the root node and moves toward the node situated at the far end of the
main, lateral, and sub lateral lines [ 5 ] (Fig. 1 ).
Main line: Line emanating from the root node.
Lateral line: Line emanating from the main line.
Sub lateral line: Line emanating from the lateral line.
Minor line: Line emanating from the sub lateral line.
Artificial neural networks (ANNs) approach for determining the bus voltages
and phase angles of a radial distribution system, without executing the load flow
algorithm, for any given load. Artificial Neural Networks (ANNs) are nonlinear
mapping structures based on the function of the human brains. They are powerful
tools for modeling, especially when the underlying data relationship is unknown.
ANNs can identify and learn correlated patterns between input data sets and the
corresponding target values. After training, it can be used to predict the output of
new independent input data. ANNs can imitate the process of learning as human
brain and can process complex and nonlinear data even if data is imprecise and
noisy. Therefore, here it is proposed to ideally suit the modeling of a balanced,
complex, and often nonlinear radial distribution system as ANNs has the great
capacity in predictive modeling and all the characters describing the unknown
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