Photovoltaic DC sub-array control system and method

摘要

A photovoltaic energy conversion system, apparatus, and method for controlling DC sub-arrays of a photovoltaic array are disclosed. The method may include coupling each of N homerun branches from N sub-arrays to an inverter via N switches and monitoring current through each of the N homerun branches. A forward current through each of the N homerun branches is compared with a forward current threshold, and any backfeed current through any of the N homerun branches is compared with a backfeed current threshold. One or more of the N switches are opened in response to either the forward current exceeding the forward current threshold or the backfeed current exceeding a backfeed current threshold.

主权项

1. A photovoltaic energy conversion system comprising:
a photovoltaic array including a plurality of sub-arrays; an inverter to convert direct current (DC) power from the photovoltaic array to alternating current (AC); a DC bus coupled to an input of the inverter; a switching component coupled between the plurality of sub-arrays and the inverter, wherein the switching component includes a plurality of individually addressable switches, each of the individually addressable switches switchably couples a corresponding one of the plurality of sub-arrays to the inverter; a sensing component including a plurality of current sensors, each of the current sensors is coupled to a corresponding one of the plurality of sub-arrays to provide a plurality of current signals, each of the plurality of current signals indicating a magnitude and direction of current flowing through a corresponding one of the plurality of sub-arrays; wherein the sensing component includes a plurality of voltage sensors, each of the voltage sensors is coupled to a corresponding one of the plurality of sub-arrays to provide a plurality of voltage signals; a protection component that receives the plurality of current signals and controls the switching component to prevent forward current through any of the sub-arrays from exceeding a forward current threshold and to prevent backfeed current through any of the sub-arrays from exceeding a backfeed current threshold; and an optimization component coupled to the sensing component, wherein a maximum power of the photovoltaic array exceeds a maximum rated power of the inverter, and wherein the optimization component monitors power applied by the photovoltaic array to the inverter and opens one or more of the individually addressable switches when the power applied by the photovoltaic array to the inverter exceeds an upper threshold, and the optimization component closes one or more of the individually addressable switches when the power applied by the photovoltaic array to the inverter falls below a lower threshold.