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**ABSTRACT**

Allocation of Phasor Measurement Units (PMU) at all the buses in a network leads to high economic cost which is not feasible. So in order to increase redundancy and obtain complete observability, PMUs must be allocated at optimal places in the network with minimum cost. In this paper, a Pattern Search Algorithm (PSA) is proposed to minimize and optimally allocate PMUs considering nonlinear sensitive constraints of buses. Sensitive buses are generated by formulating Voltage Stability Index (VSI) considering mean of voltages obtained from load flows with increasing loads. Modeling of nonlinear constraints integrated with Zero Injection (ZI) buses is considered to further minimize the number of PMUs with and without presence of zero injection buses. The redundancy at each bus is measured with Bus Observability Index (BOI) to show the importance of PMUs allocation at sensitive buses. The proposed method is programmed in MATLAB and applied on IEEE 14, 24, 30 and 57 bus systems. The results obtained are analyzed and compared with other methods available in literature to show effectiveness of proposed method.

**KEYWORDS**

Observability, Phasor Measurement Units(PMUs), Sensitive Bus, Pattern Search Algorithm (PSA), State stimation, Zero Injection (ZI).

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**Cite this paper**

M. Ravindra, R. Srinivasa Rao. (2017) A Pattern Search Algorithm Approach for Optimal Allocation of PMUs considering Sensitive Bus Constraints to obtain Complete Observability. *International Journal of Mathematical and Computational Methods, ***2**, 273-283

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