27th European Photovoltaic Solar Energy Conference and Exhibition; 3659-3660
With increasing photovoltaic power in the grids, participation in grid stabilization is demanded. In contrast to conventional electricity generation, photovoltaic power has no freely controllable input but is limited according to the irradiation available. The approach of natural photovoltaic droops cares for proper power reduction, relative to maximum available power, which corresponds to conventional power reduction relative to nominal-power. Beyond the voltage at maximum power, a negative gradient of the power curve is related to small deviations in voltage, along with the desired reduction of power. Operating on this part of the voltage-current characteristic, the irradiation proportional droop can be estimated from the operating point and transformed into the reference for the power-gradient controller. With a sufficiently rapid and stable sub-imposed power gradient controller, the inverter current always stays proportional to the in-plane irradiance, reduced according to the irradiation droop. Reduced revenues are thus fairly shared. The method offers direct accessibility from a secondary control.