# Use of DFIWG for Improvement of Voltage Stability Condition of a Power System

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## Abstract

This paper describes a method for improvement of voltage stability condition of a multi-bus power system by regulating reactive power generation at a Doubly Fed Induction Wind Generator (DFIWG). For this purpose, sensitivity relation between changes in voltage stability index at a bus with respect to change in reactive power generation of the DFIWG is derived. This relation is used to determine the required amount of change in rotor current of the DFIWG to improve the voltage stability index of the bus.

## Keywords

DFIWG Voltage stability Reactive power Rotor voltage## List of Symbols

- N
Number of buses in the system

- \(V_{i}\)
Voltage magnitude of

*i*^{th}bus- \(\delta_{i}\)
Phase angle of bus voltage of

*i*^{th}bus- \(P_{i}\)
Real power injection at

*i*^{th}bus- \(Q_{i}\)
Reactive power at

*i*^{th}bus- \(N\)
Total number of buses in the power system

*J*Load flow Jacobian matrix

- \(I_{k}\)
Voltage stability index for

*k*^{th}bus- \(B_{kj}\)
Imaginary part of

*k*^{th}row and*j*^{th}column element of bus admittance matrix- \(\beta_{m}\)
Sensitivity factor between change of voltage stability index and change of reactive power

- \(v_{ds}\)
Stator side d-axis voltage

- \(v_{qs}\)
Stator side q-axis voltage

- \(v_{as}\)
Stator side a-phase voltage

- \(v_{bs}\)
Stator side b-phase voltage

- \(v_{cs}\)
Stator side c-phase voltage

- \(i_{dr}\)
Rotor side d-axis current

- \(i_{qr}\)
Rotor side q-axis current

- \(i_{dr}^{max}\)
Maximum value of rotor side d-axis current

- \(T_{s}\)
Transformation matrix

- \(\omega_{s}\)
Angular frequency of the system

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