Dynamic phasors modeling of inverter fed induction generator

摘要

Decentralized generation and microgrids are more common in new electric power systems, where each day there is more renewable energy generation from technology such as wind energy conversion systems and photovoltaic systems, connected to the power system through electronic converters and Flexible AC Transmission Systems (FACTS) that are implemented in the whole system to guarantee the stability and the quality of electric parameters. Some of these subsystems operate in continuous mode and others in discrete mode. It is very important develop models of these technologies so that their dynamics can be analyzed in both short and long periods of time. Individual aspects, such as induction generation, are modeled with dynamic phasors technique with good results. This work presents modeling and dynamical analysis of an induction generator, which is excited by a 3-phase inverter, using the dynamic phasors technique. These models are improved here by introducing the effect of electronic converter harmonics in the model and the dynamic analysis and its effect on the calculation of active and reactive powers. The first model considers the fundamental frequency for currents and voltages, with the DC component and second-order harmonic for rotor speed; this allows observation of the oscillating mechanical behaviors in the machine's speed and torque. Later, including the first and kth harmonic introduced by commutations of the inverter, allowing analysis of oscillating dynamics of the system's electrical variables such as voltages and currents. Also, new equations are presented for calculation of active and reactive powers based on dynamic phasors, which permit knowledge of average and main distorting powers.