Ancillary services provided by renewable energy sources

There are many attempts to standardise and regulate quality of supply in electricity markets. The paper is focused on quality of supply improvement in distributed electricity systems operating in accordance with electricity market rules. Quality of supply can be ensured by Ancillary Services provided by power generating units including Renewable Energy Sources. Such power generating units are equipped with electronic power inverters installed in every phase of electric connections. The inverters are fully controlled and can operate as current sources providing not only reactive power but also compensating the asymmetry and harmonic distortion. The paper presents the rules for Nodal Area Operator, which by the adequate optimisation and control is able to balance electric energy and improve power quality using Ancillary Services.