The future power system integrated a large share of distributed generation (DG) may causes a reduction of the system rotational inertia, resulting in high frequency variations with any disturbances. An additional rotational inertia will be provided to the system if many DG units combined with relative small storage systems operate like virtual synchronous generators (VSG). This paper presents the demonstration approach for the VSGs in order to bring the VSG models developed in the laboratory into practice at two distribution test sites for both single- and three-phase applications. The results show promising results where changes in frequency and voltage are clearly counteracted by power flows from the VSG. In addition, VSG may provide a solution for hosting a large share of DG in future grids while maintaining system stability.@en

Abstract The increase of relatively small scale dispersed power generation (DG) is likely to impact the structure and operation of power generation and distribution systems. The current power system comprises multiple generators. Their intrinsic kinetic energy buffer (rotor inertia) plays an important role in short term system stability. Generators that are connected via power electronic power converters lack these kinetic buffers. Optimal power transfer from source to grid is often used as a control objective to optimize the energy yield. At power system level this approach may compromise stability. In this paper it is demonstrated that by emulation of rotor inertia, stability problems on a system level can be mitigated. For that purpose a short-term energy buffer is added to the system that can be controlled at a fast rate, thereby forming a so-called Virtual Synchronous Generator (VSG). Power system stability support then becomes an additional control objective of the DG. Maximum rotor angular speed deviation and maximum critical clearing time are used as performance indicators for the evaluation. Sizing of the short term buffer constitutes a second topic of this paper.@en

The increasing growth of dispersed generation not only changes the structure of the typical power system but also changes the way short and long term stability is handled due to lack of synchronous rotor inertia. The Virtual Synchronous Generator (VSG), which is a device that emulates synchronous inertia, is proposed and studied as a potential solution. The major components of a VSG, as far as hardware is concerned, comprise an energy storage and a power processor. This paper suggests a control algorithm for the power processor that enables multiple VSG units with different specifications to coexist and to provide for short and longer term frequency stability.@en