Electricity Production from Renewables Energies

6.4 Limitations of the penetration level

6.4.1. Participation in ancillary services

The major problem associated with decentralized energy sources is that they generally do not take part in ancillary services (voltage control, frequency control, “black” start, possibility to operate in plant shutdown, etc.). Not participating in ancillary services causes this type of source to behave as a “passive” generator from the point of view of the electric system management. Voltage and frequency controls are then transferred to conventional production groups that are equipped with alternators (action on excitation) and turbines (action on the power). The penetration level of decentralized production, i.e. the ratio between the power that it generates and the power consumed at each instant, must then be limited, in order to guarantee the network stability in acceptable conditions [CRA 08]. This is particularly true for intermittent renewable energy sources, whose primary source is hard to predict and highly fluctuating. For example, the penetration level of random renewable energies (wind and photovoltaic power) is limited to 30% of the power consumed in the French islands’ networks.

6.4.2. Untimely disconnections

Decentralized production being quite sensitive to “network” disturbances, such as voltage dips or frequency variations, often leads to a disconnection of the production during incidents on the network. This disconnection can aggravate the production-consumption unbalance and by ...