Line Impedance Emulator: Modeling, Control Design, Simulation and Experimental Validation

Abstract

The variation of line impedance has always been a great concern for grid operators and industrial users. The problem is that the reliability and quality of the supplied power are influenced by this variation. Indeed, several standards and grid requirements fix strict rules and rigorous standards when connecting or disconnecting from the public grid. In this context, this chapter proposes a full study of a line impedance emulator, which includes the power design and the control. The line impedance emulator is useful for small scale laboratories that develop distributed energy generation. Developed line impedance emulator is based on a three-phase power converter. For these converters, different controls are applied, including proportional integral and resonant controllers. For the generation of voltage reference values that correspond to expected line impedance, two algorithms are studied, namely, trigonometric functions-based algorithm and voltage drop-based algorithm. The theoretical study is supported by simulation and experimental results.