Power Dithering Algorithm to Avoid the Overcoming of the Voltage Limit in Presence of DG on Distribution Networks

V. Calderaro, V. Coppola, V. Galdi, and A. Piccolo (Italy)


Dispersed generation, voltage regulation, renewable energy, power factor control, dithering algorithm.


In the last years the growing interest about sustainable growth and ecological problems joint with the increasing need of energy have encouraged the widespread development of medium and small power generators based on renewable sources. The increasing use of such dispersed generators (DGs) causes new problems in terms of distribution network management and planning, with effect on the power quality, voltage profile or protection aspects. One of the problems arising on MV/LV distribution network, especially in weakly areas like in rural ones, is related to the bus overvoltage at the point of common coupling (PCC). This overvoltage, usually due to the injection of a large amount of power from unschedulable DG and a small power demand by the loads, can trip the overvoltage protection relays of DGs disconnecting them from the grid. In this paper is proposed a local control strategy for DG systems based on the dithering algorithm. The proposed solution, operating on the electronic interface of the power generator, introduces or absorbs reactive power if the voltage at PCC is close to the limits, increasing the total active power injected by renewable sources.

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