Maximizing power in a photovoltaic distributed power system

• US 9,812,984 B2
• Filed: 01/30/2013
• Issued: 11/07/2017
• Est. Priority Date: 01/30/2012
• Status: Active Grant

• Current Assignee: Solaredge Technologies Incorporated
• Original Assignee: Solaredge Technologies Incorporated
• Inventors: Yoscovich, Ilan
• Primary Examiner(s): Barnie, Rexford
• Assistant Examiner(s): Ly, Xuan
• Application Number:
  US13/754,059
• Publication Number:
  US 20130193765A1
• Time in Patent Office: 1,742 Days
• Field of Search: 307 45
• CPC Class Codes: H02J 2300/10 The dispersed energy generation being of fossil origin, e.g. diesel generators
• CPC Class Codes: H02J 2300/26 involving maximum power point tracking control for photovoltaic sources maximum power point systems in particular G05F1/67
• CPC Class Codes: H02J 3/38 Arrangements for parallely feeding a single network by two or more generators, converters or transformers
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/46 Controlling of the sharing of output between the generators, converters, or transformers
• CPC Class Codes: H02M 7/42 Conversion of dc power input into ac power output without possibility of reversal
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A power harvesting system including multiple parallel-connected photovoltaic strings, each photovoltaic string includes a series-connection of photovoltaic panels. Multiple voltage-compensation circuits may be connected in series respectively with the photovoltaic strings. The voltage-compensation circuits may be configured to provide respective compensation voltages to the photovoltaic strings to maximize power harvested from the photovoltaic strings. The voltage-compensation circuits may be include respective inputs which may be connected to a source of power and respective outputs which may be connected in series with the photovoltaic strings.

Claims

1. A system comprising:

a plurality of parallel-connected compensated photovoltaic strings, each compensated photovoltaic string including;

a photovoltaic string having a series-connection of photovoltaic cells; and

a voltage-compensation circuit having an input connected to a source of power independent from power provided by the photovoltaic string, wherein the voltage-compensation circuit is configured to produce, from the source of power, an output power having an adjustable compensation voltage at a voltage output connected in series with a voltage generated by said photovoltaic string such that a total voltage of the compensated photovoltaic string maintains a predetermined value;

a central controller connected to the voltage-compensation circuits and configured to control the adjustable compensation voltages; and

a power sensor connected to a direct current output of the plurality of the parallel-connected compensated photovoltaic strings and to the central controller, wherein the power sensor is configured to sense a power parameter at the direct current output and provide the sensed power parameter to the central controller,

wherein the central controller is configured to control the adjustable compensation voltages based on a maximum power from all the parallel-connected compensated photovoltaic strings and based on the sensed power parameter.

2. The system of claim 1, wherein each voltage-compensation circuit comprises one of:

an alternating current (AC) to direct current (DC) converter, wherein the AC to DC converter includes an input connected to the source of power, and wherein the AC to DC converter includes an output configured to provide the adjustable compensation voltage; and

a DC-to-DC converter, wherein the DC to DC converter includes an input connected to the source of power, and wherein the DC to DC converter includes an output configured to provide the adjustable compensation voltage.

3. The system of claim 1, wherein the source of power is provided by an AC power grid.

4. The system of claim 1, wherein each compensated photovoltaic string further comprises:

a sensor adapted to measure at least one circuit parameter of the photovoltaic string, wherein the voltage-compensation circuit is adapted to adjust the adjustable compensation voltage based on the at least one measured circuit parameter.

5. The system of claim 4, wherein the at least one measured circuit parameter includes a current flowing in the photovoltaic string.

6. The system of claim 4, wherein the at least one measured circuit parameter includes a voltage across the photovoltaic string.

11. The system of claim 1, wherein each voltage compensation circuit provides a respective adjustable compensation voltage so as to maximize power harvested from the respective photovoltaic string connected to the respective voltage compensation circuit.

12. The system of claim 1, wherein each of the voltage compensation circuits is connected to the same source of power.

13. The system of claim 1, wherein the predetermined value for each of the plurality of parallel-connected compensated photovoltaic strings is the same.

14. The system of claim 13, further comprising:

a power converter having an input attached to an output of the plurality of parallel-connected compensated photovoltaic strings and having an output configured to provide the source of power to each of the voltage compensation circuits.

7. A method comprising:

connecting a direct current output of a plurality of parallel-connected compensated photovoltaic strings to a sensor, wherein each compensated photovoltaic string of the plurality of parallel-connected compensated photovoltaic strings comprises one or more photovoltaic cells connected in series with a voltage-compensation circuit;

connecting an input of each voltage-compensation circuit to a source of power independent from power provided by a corresponding compensated photovoltaic string;

adjusting an output compensation voltage produced on an output of each voltage-compensation circuit based on an optimal value of a total voltage of the corresponding compensated photovoltaic string;

sensing a power parameter at the direct current output of the plurality of the parallel-connected compensated photovoltaic strings; and

controlling the output compensation voltage produced on the output of each voltage-compensation circuit based on a maximum power from all the parallel-connected compensated photovoltaic strings and based on the sensed power parameter.

8. The method of claim 7, wherein the power parameter comprises.

9. The method of claim 7, wherein the power parameter comprises.

10. The method of claim 7, further comprising:

generating the output compensation voltage from outputs of a direct current (DC) to DC converter receiving the source of power at inputs of the DC to DC converter.

15. A controller comprising:

a first plurality of inputs, each of the first plurality of inputs connected to a compensated photovoltaic string of a plurality of parallel-connected compensated photovoltaic strings, each compensated photovoltaic string comprising;

a photovoltaic string having a series-connection of photovoltaic cells; and

a voltage-compensation circuit having an input connected to a source of power independent from power provided by the photovoltaic string, wherein the voltage-compensation circuit is configured to produce an output power having an adjustable compensation voltage at a voltage output; and

a second input connected to a power sensor, the power sensor connected to a direct current output of the plurality of the parallel-connected compensated photovoltaic strings, wherein the power sensor is configured to sense a parameter at the direct current output and provide the sensed parameter to the controller,

wherein the controller is configured to control the adjustable compensation voltage at the voltage output of each voltage-compensation circuit based on a maximum power from the plurality of parallel-connected compensated photovoltaic strings and based on the sensed parameter.

16. The controller of claim 15, wherein the parameter is a current at the direct current output.

17. The controller of claim 15, wherein the parameter is a voltage at the direct current output.