Coordinated control logic of photovoltaic and regenerative electric power in distribution system and verification of its effect

This paper reports simple and effective control logic for connecting abrupt, steep and short-term power sources (for example, regenerative power from electric railway vehicles) to distribution lines with renewable energy units connected. With conventional centralized control systems, power conditioner units were unable to keep voltage of the distribution line within an acceptable range when extremely steep regenerative power flowed backward in the line, due to control delay. This new logic has power conditioner units exchange calculated control amounts between themselves repeatedly in fixed intervals. When voltage of the distribution line rises relatively slowly from renewable energy generators such as PV, the power conditioner unit can suppress the voltage rise immediately with no control delay, if regenerative power flows backward to the lines and voltage departure from an acceptable range is foreseen. This logic needs no central control unit in particular, as its power conditioner units can effectively execute and coordinate control between themselves. We verified the effectiveness of this logic through an experiment at our demonstration facility.