Solar photovoltaic systems
Improved techniques for photovoltaic power generation are described. Inverter failure is can be a significant problem in solar photovoltaic systems as it can lead to loss of opportunity to harvest energy. A solar photovoltaic (PV) power generation system is described comprising solar PV panels and power conditioning units. A dc power distribution bus is coupled to the solar PV panels and the power conditioning units to switchably share dc power from the solar PV panels between the power conditioning units. Power distribution controllers detect a faulty power conditioning unit and reroute power from a solar PV panel coupled to the faulty power conditioning unit to other power conditioning units via the dc distribution bus.
1. A fail-safe photovoltaic power conversion system comprising:
a DC power source coupled to and configured to supply DC power to a first power conditioning unit;
a second power conditioning unit coupled to a DC power distribution bus, wherein the first and second power conditioning units each comprise a DC to AC converter for converting DC power to AC power;
and
a power distribution controller coupled to the first power conditioning unit and the DC power distribution bus, the power distribution controller comprising a fault detector to detect a failure in the first power conditioning unit that results in the first power conditioning unit ceasing to convert power and circuitry that responds to the detected failure by redirecting the DC power provided by the DC power source to the DC power distribution bus.
2. The fail-safe photovoltaic power conversion system of claim 1 wherein the circuitry of the power distribution controller responds to a detected failure by changing a state of one or more switches from a first state in which the DC power source is coupled to the first power conditioning unit to a second state in which the DC power source is coupled to the DC power distribution bus.
3. The fail-safe photovoltaic power conversion system of claim 2 wherein the one or more switches are solid-state semiconductor switches.
4. The fail-safe photovoltaic power conversion system of claim 1 wherein the power distribution controller has circuitry configured to notify a second power distribution controller of a detected failure of the first power conditioning unit and in response, the second power distribution controller couples the second power conditioning unit to the DC power distribution bus.
5. The fail-safe photovoltaic power conversion system of claim 4 wherein the power distribution controller notifies the second power distribution controller using a wireless communication circuit.
6. A power distribution controller comprising:
fault detection circuitry operable to detect a failure of a first power conditioning unit configured to convert DC power to AC power wherein the failure results in the first power conditioning unit ceasing to convert DC power to AC power;
switch controller circuitry operable to configure one or more switches between a first state in which the first power conditioning unit is configured to receive power from a DC power source and a second state in which a DC power distribution bus is configured to receive the power from the DC power source; and
logic circuitry configured to respond to the detected failure of the first power conditioning unit by commanding the switch controller circuitry to change a state of the one or more switches from the first state to the second state.
7. The power distribution controller of claim 6 further comprising circuitry configured to notify a second power conditioning controller of the detected failure of the first power conditioning unit and in response, the second power conditioning controller couples a second power conditioning unit to the DC power distribution bus.
8. The power distribution controller of claim 6 wherein the DC power distribution bus couples a plurality of power conditioning units in series.
9. The power distribution controller of claim 6 wherein the DC power distribution bus couples a plurality of power conditioning units in parallel.
10. The power distribution controller of claim 6 wherein one or more diodes are used in combination with the one or more switches to transition between the first state and the second state.
11. The power distribution controller of claim 6 wherein the first power conditioning unit has circuitry configured to receive DC power from the DC power source and convert it to AC power for delivery to an AC mains.
12. The power distribution controller of claim 6 wherein the fault detection circuitry is configured to detect a short circuit.
13. The power distribution controller of claim 6 wherein the one or more switches are solid-state semiconductor switches.
14. A photovoltaic (PV) power generation system comprising:
a plurality of DC power sources;
a plurality of power conditioning units each configured to convert DC power to AC power, each power conditioning unit comprising an input coupled to at least one of the plurality of DC power sources, and an output that outputs AC power;
a DC power distribution bus that is coupled to the plurality of DC power sources and to the plurality of power conditioning units; and
a plurality of power distribution controllers each coupled to a corresponding power conditioning unit, wherein each power distribution controller comprises a fault detector that is configured to detect a failure in the corresponding power conditioning unit, and in response discontinue a supply of DC power to an input of the corresponding power conditioning unit and to redistribute DC power through the DC power distribution bus to other power conditioning units of the plurality of power conditioning units, wherein the failure results in the corresponding power conditioning unit ceasing to convert DC power to AC power.
15. The PV power generation system of claim 14 wherein the plurality of power distribution controllers each have circuitry configured to notify one or more other power distribution controllers of a detected failure in a corresponding power conditioning unit and in response, at least one of the other power distribution controllers couples a corresponding power conditioning unit to the DC power distribution bus.
16. The PV power generation system of claim 15 wherein the plurality of power distribution controllers each have a wireless communication circuit to notify the one or more other power distribution controllers of a detected failure.
17. The PV power generation system of claim 14 wherein the fault detector is configured to detect a short circuit.
18. The PV power generation system of claim 14 wherein each power distribution controller responds to the detection of the failure in the corresponding power conditioning unit by controlling one or more switches to discontinue supplying DC power to the corresponding power conditioning unit and to redistribute the DC power to the DC power distribution bus.
19. The PV power generation system of claim 18 wherein the one or more switches are solid-state semiconductor switches.