Modeling and Analysis of Three Phase Stand Alone Induction Generator under Single Phase Load

Abstract

II. IntroductionDue to the increased emphasis on the energy issues and problems, concentration has been focused upon developing autonomous electric power supplies to be operated in remote and rural areas where electric services is unavailable from existing or nearby grids. These types of power sources can be used even in regions supplied by network grids in the event of power interruptions. Among such types that have received a notable attention and importance is the three-phase self-excited induction generator due to its numerous advantages such as simple design, robustness, and low installation and maintenance costs [1][2][3][4]. Experimental works and computer simulations have been extensively performed in order to model and analyze both steady state and transient performance of the SEIG under balanced operating conditions. However, the unbalanced operation of the SEIG has been given little attention despite its practical needs. There are two main methods to predict the steady state performance of the SEIG under balanced operating conditions. The first method is based on the generalized machine theory [5]. The second method is based on the analysis of the generalized per-phase equivalent circuit of the induction machine by applying either the loop impedance or the nodal admittance concept [6,7]. Furthermore, other studies have concentrated only on the single-phase self-excited induction generator and its voltage regulation improvement [8]. The influence of the terminal capacitance has been investigated in [9,10]. The previous studies have centralized mainly on modeling and analyzing the performance of SEIG under only balanced operating conditions. In this paper, modeling and performance analysis of SEIG under single phase loading conditions in the steady state are presented. A model of a delta-connected SEIG feeding a deltaconnected load is derived in detail. The effect of the machine core losses is considered by representing the core resistance as a second order polynomial in terms of X m . Furthermore, the magnetizing reactance has been included in the negative sequence equivalent circuit as a variable. The positive and negative sequence equivalent circuits are used to model the SEIG. The final characteristic equation is reached by equating both the positivesequence and negative-sequence voltages across the SEIG and the load. Resistance, reactance, and impedance respectively. C, X C Excitation capacitance and its reactance. F, vPer unit frequency and speed respectively. V, IVoltage and current respectively.