Hybrid partial power processing system
The hybrid partial power processing system includes differential power processing converters DPPs having low power ratings, which are used to exchange differential power between two adjacent PV modules, or between PV modules and a line capacitor (C lin ) connected in series within the same string. The exchange of differential power by DPPs is needed to track the maximum power point of each PV module in the string. The DC power optimizing converter (DC-PO) is a DC/DC power converter used to feed current (power) from a PV module to C lin . The DC-PO is driven to track the maximum power point (MPP) of one PV module, and the MPP of each one of the remaining PV modules in the string is tracked by a DPP.
1. A hybrid partial power processing system, comprising:
a DC power optimizing converter (DC-PO) having an input and an output, the output of the DC-PO having a first output terminal and a second output terminal;
a photovoltaic (PV) module connected to the input of the DC-PO;
a line capacitor C lin having a downstream side and an upstream side, the downstream side being connected to the first output terminal of the DC-PO, the upstream side being connected to the second output terminal of the DC-PO;
at least one downstream PV module connected in a serial string to the downstream side of the line capacitor C lin ;
at least one upstream PV module connected in a serial string to the upstream side of the line capacitor C lin ; and
for each of the at least one downstream PV modules and for each of the at least one upstream PV modules, a corresponding differential power processing converter (DPP) having two differential leads connected in parallel across the corresponding downstream or upstream PV module and a third lead connected to a neighboring downstream or upstream PV module or the line capacitor C lin ;
wherein the hybrid partial power processing system is configured to allow exchange of differential power between two adjacent PV modules or between a PV module and the line capacitor C lin , thereby aiding speed of maximum power point tracking (MPPT) of the hybrid partial power processing system.
2. The hybrid partial power processing system according to claim 1 , wherein each of the DPP is selected from a group consisting of a bidirectional DPP and a unidirectional DPP.
3. The hybrid partial power processing system according to claim 1 , wherein said DC power optimizing converter (DC-PO) comprises a plurality of DC-POs connected across the line capacitor C lin .
4. The hybrid partial power processing system according to claim 1 , wherein the DPPs and said DC-PO are selected from a group consisting of isolated converters or non-isolated converters.
5. The hybrid partial power processing system according to claim 1 , wherein the DPPs and said DC-PO comprise converters selected from a group consisting of buck DC/DC converters, boost DC/DC converters, buck-boost DC/DC converters, and resonant DC/DC converters.
6. The hybrid partial power processing system according to claim 1 , wherein the two differential leads of said corresponding differential power processing converter (DPP) are connected across a plurality of the PV modules.
7. The hybrid partial power processing system according to claim 1 , further comprising at least one power exchanging DC-DC converter connected in parallel with said DC-PO.
8. The hybrid partial power processing system according to claim 1 , wherein said corresponding differential power processing converter (DPP) includes a microcontroller using only local measurements of voltages and currents in said DPPs two ports to track a maximum power point (MPP) of the corresponding PV module for local control of the MPPT.