Inverter control modeling in DIgSILENT Power Factory to analyze the effects of DG units on the distribution grid

With the spread of distributed generation (DG) sources which are using renewable energy, and also with the expected propagation of electric vehicles that have to be recharged, more and more inverter-based sources and loads are likely to appear on the electricity grid. One of the main issues of the penetration of these grid-tied inverters is the possible harmonic resonance formed between the inverter output impedance and the grid impedance due to the PWM switching frequencies of these inverters. Thus, to precisely model the effects that these equipments might have on the grid (in respect of grid stability and power quality), appropriate models of the inverters are required. A detailed inverter model is presented in this paper and is validated through simulations in DIgSILENT Power Factory.