Interharmonic current sharing in islanding operation of inductive microgrid via enhanced I‐P droop scheme

Abstract

Abstract The considerable expansion of non‐linear loads with interharmonic currents characteristic such as induction furnace, cycloconverter and variable‐speed drive is one of the new and important challenges in the control of industrial microgrids. For this reason, this paper presents an enhanced control scheme that tries to share power and especially interharmonic currents through parallel inverters accurately, which is not addressed in previous literature. In this regard, assuming the inherent delays of digital control, the proposed control strategy firstly suppresses the inherent impedances of inverters, especially in interharmonic frequencies. Then, the enhanced impedance‐power (I‐P) droop scheme is employed based on virtual inductors to compensate for the mismatch of line impedances and to achieve proper power‐sharing. Besides, novel techniques are introduced in the proposed structure to limit the values of virtual inductances and even to benefit from the negative virtual impedance method. The notable feature of the presented scheme is the sharing of interharmonic currents with high accuracy and low computations. Finally, the effectiveness of the proposed method is evaluated through simulation and experimental results.

Keywords

• Control of electric power systems
• Distributed power generation
• Distribution networks
• Power supply quality and harmonics
• Drives