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Title:	Optimal under voltage load shedding strategy using reactive power tracing and lightning search algorithm
Authors:	Renuga Verayiah (P55895)
Supervisor:	Azah Mohamed, Prof. Dr.
Keywords:	Electric power systems
Issue Date:	11-Jul-2017
Description:	Existing power systems are significantly susceptible to voltage instability problem since such systems are stressed with the huge power transfers across the grids. To guarantee power system stability during stressed conditions, under voltage load shedding is performed as a control action. The key principles associated with load shedding are determination on the amount of load to shed, the timing to execute load shedding event and appropriate location for load shedding. In this study, a new method is proposed for determining optimal amount of load shed for under voltage load shedding scheme using reactive power tracing and lightning search algorithm (LSA). The reactive power tracing method is applied to develop a novel reactive power tracing capable index, named as LQP_LT for determining weak load bus locations. Unlike the commonly applied real power tracing, this method presents the reactive power tracing utilizing the proportional sharing method with all the line reactive losses being taken into consideration in the network study. The reactive power tracing algorithm is modified to alleviate the sparse matrix issues and it is improvised for large networks. It is integrated with the LQP_LT index formulation to generate priority ranking list of weak load buses. To determine optimal amount of load shed for under voltage load shedding, a multi-objective optimization formulation is developed by minimizing the total LQP_LT index and the total amount of load shed. Other meta-heuristic optimization techniques such as particle swarm optimization, back tracking search and firefly algorithms were compared with the LSA. The LQP_LT index was tested on the IEEE 14 bus and 57 bus systems and the resulting priority ranking list is found to have successfully determined the weak load buses for load shedding in the test systems. Comparison with other stability indices and detailed study conducted revealed that the LQP_LT has better sensitivity and response towards determining the location of the weakest load bus for under voltage load shedding implementation. Comparison study revealed that under voltage load shedding optimization using LSA which adapts the new LQP_LT index for weak bus location determination resulted in the least optimized amount of load shed for overall system voltage recovery. The proposed LSA gives the least amount of load shed (3.92% and 4.99 % of real and reactive load) from the total system demand for 0.95 p.u overall system voltage recovery at highest convergence rate compared with load shed percentages of 4.00%, 3.98% and 4.25% for real load and 5.40%, 5.30% and 5.42% for reactive load, using the particle swarm optimization, backtracking search algorithm and firefly algorithm technique, respectively in the IEEE 57 bus system.,Ph.D.
Pages:	201
Call Number:	TK1001.R443 2017 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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