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New paradigms in the modern power system should be introduced to student of electrical engineering, or engineer in training, as early as possible. Besides class-room study, experimental exercise may be introduced to help the student understand the concept of microgrid. One main challenge is the power electronics converter, which connects the distributed energy source to the existing power grid. This study modeled and developed a grid-connected inverter that is useful for providing a close to real application for a student or engineer in training. This development is important for microgrid learning to give practical perspective to the student. A grid-connected inverter for distributed generation was developed at laboratory scale. The grid-connected inverter was developed modularly to make it easier for the student to understand the basic concept of grid-connected inverter building blocks, as well as its function as a whole. The developed grid-connected inverter was intended to be able to operate on two different mode: grid-forming mode and grid-injecting mode. Experiments were conducted to verify the results.

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Virtual impedance concept provides the impedance effects without need to put real physically impedance in the circuit. In power system, oscillation will not occur as long as the impedance seen by turbine‐generator set is ‘passive’. In order to ensure the impedance is seen as ‘passive’ by the turbine‐generator set, a series resistor can be placed in the system. This paper proposes implementation of virtual resistor concept in grid connected power electronic converter to replaced the aforementioned series resistor, then analyze its impact on subsynchronous oscillation phenomena. It can be shown that virtual resistor can improve the negative region of converter input admittance. Moreover, it also gives us better damping in system involving grid connected inverter. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

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A grid‐connected inverter offers good operation and controllability; however, there is a risk of local instabilities due to particular control schemes. As long as the input admittance is positive at a particular resonance frequency, the risk of local instability can be suppressed. In this paper, an attempt to improve the input admittance of the grid‐connected inverter (GCI)[vnsn1] using a virtual resistor is proposed. The impact of the virtual resistor on the inverter's passivity is analyzed by observing the input admittance of the inverter. Numerical analysis shows that the employment of the virtual resistor gives better input admittance to the GCI, particularly in the low‐frequency regions. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.