Retrofit of distributed generation vs. frequency control in smart grids at overfrequency

The paper presents an operation and frequency control in a small smart grid during overfrequencies. The studied grid consists of a photovoltaic power plant representing a distributed generation, a conventional source represented by a small synchronous generator with the speed controller and a load. The frequency control defined by a recent ENTSO-E Network Code for generating units of type B is applied on the photovoltaic power plant operation. Moreover, requirements of an ongoing distributed generation retrofit program are applied too. An influence of applied restrictions on frequency changes and a smart grid power balance is studied. A special attention is paid to the application of a limited frequency sensitive mode for overfrequency to the photovoltaic power plant operation. Its application to new as well as already installed distributed generation should help to reduce its impact on network operation at overfrequencies. Unfortunately, these requirements seem to be a dangerous tool, which will postpone the application of a smart grid concept to real distribution networks. That is because they suppress the possibility to adjust the active power in the smart grid at overfrequencies lower than 50.2 Hz. And thus, they go against the basic principles and expected advantages of smart grids.