Novel approach for signal selection and optimal control in emerging Wide Area monitored systems

This paper presents a novel scheme for selection of signals for Wide area monitoring and control of power system. The twin problem of placement of Phasor Measurement Units (PMU) for observability and placement of dynamic controllers for controllability are solved separately using different techniques. The selected signals are applied as input and output respectively for the centralized Wide area controller. A Principal Component Analysis (PCA) based coherency identification method has been adopted for selection of signals for observability, while a novel attempt has been made to apply the method of dimension reduction by Sequential Orthogonalisation (SO) for the selection of signals for controllability. A simple damping controller circuit that takes inputs from wide area signals is considered for controlling the inter-area oscillatory modes using the conventional power system controllers. The objective of the study is to determine the applicability and effectiveness of existing traditional damping devices with Wide Area inputs, in complex power systems such as Indian grid, with only traditional controllers. The focus of this study is on inter-area oscillatory modes, for which the modified 39-bus New England Test System (NETS) has been taken as test case. A large number of operating conditions have been considered for simulations, and the results show that the proposed scheme provides marked improvement in the damping performance of the system.