A STATCOM Controller for Small Signal Stability using Polynomial Algorithms in a Horizontal Axis Wind Farm Power System A.U. Lawan, N. Magaji and H.Musa Department of Electrical Engineering/ Bayero University, Gwarzo Road, Kano State, NIGERIA aulfagge@yahoo.com nmagaji2000@yahoo Abstract—This paper investigates three polynomial strategies in damping oscillations in a horizontal axis turbine plant power systems, to demonstrate the influence of the introduction of the STATCOM in the power system, a comparative study is implemented using various polynomial algorithm control approaches to a horizontal wind axis turbine power system in- cooperating a static synchronous compensator (STATCOM). The proposed controllers’ designs are based on a linear time invariant model of the plant and state feedback scheme. First, the linearized mathematical model of STATCOM is derived. Then, using polynomial algorithms as a state feedback algorithm, a state feedback control law is derived. The proposed control strategy is tested on SMIB power system with wind turbine by digital computer simulations using matlab/simulink and a power analysis toolbox. Comparison of the polynomial matching results of the controllers establishes the superb nature of polynomial approximation approach. Key-Words:- STATCOM, Polynomial Algorithms,Suplemant -ary damping controller, DFIG, ITAE, Butterworth, and Low frequency oscillations I. INTRODUCTION Crisis due to the world’s continued dependence on fossil fuels which accounts for about 75% of world energy demand is drastically increasing, and world consumption currently amounts to more than 80 million barrels of oil a day. It is obvious however, that future global demand for oil will far exceed supply [1]. The objective of the EEC is by 2020 to achieve 12%of all energy produced from the alternate wind power. This development rises from global needs for cleaner energy, more away from fossil fuels of which the greenhouse gases emitted is by far more than that of wind turbine plants [2]. A wind turbine can be thought like or as the reverse of an electric fan. The kinetic energy of the wind is converted to the rotation of a shaft, which connects to an electrical generator. A synchronous generator is used for constant speed rotors, and if connected to the grid, it has to be carefully controlled to run at the specific grid frequency. Direct grid coupling could be achieved on wind farm plants where rotors are all rotating at the same angular velocity. However, the majority of modern-day wind plants use double fed induction generators (DFIG) which can be used at variable speeds. These use power electronics to maintain alternating current at 50 or 60 Hz even though the generator shaft speed is varying. The main advantage of the induction generators is that they don’t need sliding commutator brushes, and are more reliable devices. The fluctuation of wind causes fluctuations in the power delivered by the wind turbine farm to the electricity network, therefore, up grading power system to improve voltage stability, frequency stability and power quality is of paramount importance of research and development in the wind power development. The incorporation of Doubly Feed Induction Generators (DFIG) and a FACTS Controllers in wind turbines, improves stability and frequency of the voltage through their decoupled control of active and reactive power. However, the power delivered by the wind turbine farm to the electricity network brings about many defects like; a. Frequency fluctuations due to power fluctuations. b. Harmonic emission if not filtered due to the presence of electronic power converters in the wind farm turbines. c. Voltage flickers and fluctuations due to aerodynamic aspects of wind farm turbines [3].etc. Power system frequency oscillations could be up to 46Hz as in the case of torsional oscillation but a frequency in the range between 0.1 and 2 Hz is classified as a low frequency of oscillations. In order to promote the integration of wind farms into the electrical network, Flexible AC Transmission Systems are widely used.