ABSTRACT
The consistent increase in energy needs and the relevant concerns environmental impacts are propelling the diffusion of renewable-energy-based power sources. The gradual change from a unidirectional power flow to a bidirectional power flow network endowed by small prosumers faces several new challenges, such as uncontrolled power flow, under- and overvoltage, quality of energy, higher harmonic circulation, which may trigger resonances, and improper tripping of protections. The conventional rotating generators are inevitably controlled as a voltage source, while distributed generation systems (DGSs) may act as a controlled voltage source or as a controlled current source, depending on the type of operation, type of grid interface, and applicable standards. The nonfundamental frequency terms can be generated similarly in fundamental frequency terms by only applying the concept of conductance and susceptance for the n-harmonic frequency. When there is an arbitrary connection of small-size generators across distribution network, there is a potential impact on the grid power quality.
