Chapter -5
Conclusions and Scope for Future Work
In the research work undertaken, research was carried out on the issues of
voltage stability (VS), available transfer capacity (ATC) and application of
intelligent techniques to these issues.
5.1 Conclusions
The literature survey pertinent to the present work reveal that minimum
research work has been carried out on the combined issues of voltage stability,
available transfer capability and application of intelligent techniques and also
availability of different heuristic techniques to solve these issues.
In this concluding chapter the salient outcomes of the twelve proposed methods
regarding the above issues are summarized and useful conclusions are presented.
Also a few aspects which may be explored for further research are outlined.
The repeated power flow (RPF), continuation power flow (CPF) are replaced
with the proposed continuation repeated power flow (CRPF) for the analysis of
voltage stability and as well as to obtain the ATC computations. It is because
of the results obtained through the proposed CRPF has proved that, it is the
best method as compared to the RPF and CPF, it is due to fact that, the
proposed CRPF will have the advantages of both methods and not having the
disadvantages of both methods. In addition to this fact, an automatic desired
output data file will be created and it has been extended to create proposed
continuation repeated optimal power flow (CROPF) as an alternative for the
conventional OPF.
So far in the literature, only voltage stability constrained power margin using
power flow, optimal power flow and some intelligent techniques are available.
In this thesis these concepts related to available transfer capability were
extended using repeated power flow, continuation power flow, optimal power
flow and, intelligent techniques like radial basis Function neural network, back
propagation neural network and adaptive neuro fuzzy inference system.
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Therefore proposed voltage stability constrained ATC using intelligent
techniques is developed in this thesis.
Proposed secured voltage stability power margin (SVSPM) method is useful to
find the SVSPM of any desired bus, it is achieved by integrating the different
methods of voltage stability analysis. The obtained results through this
SVSPM are useful to assess the first security check point and make the power
engineer to be alert with the necessary measures in order to prevent the voltage
instability and to take precautionary steps if such situation arises.
The CRPF and CROPF methods are used to obtain the voltage stability
constrained ATC at desired buses of different test systems. The results
obtained through these methods are useful to estimate the ATC at different
loading conditions and the number of tables presented in the chapter-3 will be
useful as the readymade reference for the power business transactions of
Indian southern region power system as well as for IEEE 9-bus and IEEE 24-
bus system.
The proposed MIMO ANFIS is developed and tested scrupulously by
cascading three single input, single output ANFIS through well-defined
programming to overcome the drawback of single output of ANFIS. The
proposed technique will become great advantage to the ANFIS, as ANFIS
have an ability to automatically learn and adapt to non-linearity and the
ANFIS has been proved as the best intelligent technique in modeling
applications. This proposed method is very useful for the analysis of voltage
stability under online environment.
Proposed a hybrid intelligent technique by integrating ANFIS and RBFNN to
get multiple outputs.
The proposed Multi-Objective decision based ATC (MODBATC) is used to
obtain seven different purpose ATC computations. The main intension of
proposing this concept is to consider all possible factors in computing and for
effective usage of ATC. In the open market circumstances, different
commodities are available with different quality for the different customers.
Similar to this, the proposed method is useful for taking appropriate decision in
selecting appropriate ATC because ATC concept is related to the deregulated
power system. In this way this proposed concept will be useful to establish
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different ATC meters at load dispatch centres of deregulated power system as
similar to different country clocks at one place.
Proposed a technique for on-line monitoring of ATC at load dispatch center
using adaptive neuro fuzzy inference system (ANFIS) and also developed its
hardware implementation in the laboratory.
In addition to the above conclusions, some useful conclusions related to the
intelligent techniques are as follows.
The RBFNN, BPNN, proposed MIMO ANFIS are trained with the
conventional data obtained from the CRPF for the analysis of voltage stability and
computations of ATC. The results obtained through these intelligent methods are not
iterative and not involving any complex mathematical equations. From these results
it is observed that under normal operating conditions, the results obtained through
the conventional methods and intelligent methods are almost coincidence with each
other resulting to almost zero error and this has been proved with the different case
scenarios of different test systems for the validation.
Hence by using intelligent technique high accuracy is achieved and the overall
computation time is reduced considerably as the conventional methods are time
consuming and are tedious for the large power system. Therefore, a power system
engineer can train the intelligent technique with the existing practical power flow
data for effective monitoring of the power system under online condition. The
obtained results can be used to develop different intelligent control equipment
instead of depending on the knowledge of expert power engineer.
All the proposed methods are applied to four test systems namely: IEEE 9-bus,
IEEE 24-bus, Indian SREHV 24-bus, Indian latest SREHV 72-bus and obtained
relevant and appropriate results.
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5.2 Scope for Future Work
Following are the potential directions useful to extend this research work, which
can be explored for the future research work:
Support vector machines can be tested and developed for combined voltage
stability and ATC.
Use of FACTS devices along with intelligent techniques for the
enhancement of voltage stability constrained ATC.
A Fuzzy modelling approach can be developed and tested.
A novel hybrid models can be developed using ANN, fuzzy logic and
evolutionary algorithms.
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