Abstract This paper presents a constant voltage operation of a Six-Phase Self-Excited Induction Generator (SPSEIG) driven by a fixed speed wind turbine using an Ant colony optimisation (ACO) technique to predict the behaviour of a the machine. In this paper, an attempt has been made to estimate the excitation capacitance requirements of a SPSEIG for maintaining rated terminal voltage and frequency. The range of capacitance variation required for maintaining constant terminal voltage while supplying a load of variable magnitude is evaluated. Analytical approaches, suitable for all the configurations of shunt capacitances such as variable excitation capacitance connected across (i) single three-phase winding set only and (ii) both the three-phase winding sets of an SPSEIG for operation as a simple shunt on no load and pure resistive load, are presented. The mathematical model developed is based on loop impedance method using graph theory. It is shown that the proposed technique is very effective and useful for making the SPSEIG feasible for remote areas with wind potential. The proposed approach is tested and compared with Genetic Algorithm (GA) and Fmincon technique.