Increasing voltage headroom for the connection of distributed generation - site trials of the supertapp N+ AVC relay

Generation causes problems for existing voltage control schemes. Fixed source voltage schemes tend to have a high set-point to allow for voltage drop under high load conditions. This leaves very little headroom for generator voltage rise under low load conditions. Load drop compensation helps, but it is difficult to fiddle the characteristic such that network voltage remain above the statutory lower limit at high generation and high load. Finally, schemes which assume a typical load power factor in order to calculate cross network circulating (reactive) current fail when generation at or near unity power factor is added.