Modelling and analysis of unsymmetrical multi-microgrid operation of active distribution networks

A hybrid microgrid is proposed with the purpose of standardization having dedicated local controller algorithms for generalized indefinite instantaneous power Distributed Generators (DGs: Wind, PV) and definite instantaneous power DGs (sources that do not have intermittent characteristics). The first controller is based on DC link voltage control while the latter is based on conventional droop control. Firstly, stability analysis of the proposed microgrid is performed. Different from literature results, it is observed that oscillations between output filters are also effective for stable operation as well as non inductive line couplings of droop controlled inverters. Critical value for the coupling inductance in terms of oscillatory effect has been formulised for the stability. The analytical results are proven with simulations and also some critical aspects of Multi-microgrid operation have been brought out.