IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0016970
(2011-01-29)
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등록번호 |
US-8461508
(2013-06-11)
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발명자
/ 주소 |
- Seymour, Eric
- Gilmore, Jack Arthur
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출원인 / 주소 |
- Advanced Energy Industries, Inc.
|
대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
0 인용 특허 :
33 |
초록
▼
A photovoltaic system has a power converter connected by power rails to a plurality of photovoltaic strings, each string has serially connected photovoltaic panels and switches. The switches divide each string into sections, and the strings are distributed in electrical parallel paths over a plurali
A photovoltaic system has a power converter connected by power rails to a plurality of photovoltaic strings, each string has serially connected photovoltaic panels and switches. The switches divide each string into sections, and the strings are distributed in electrical parallel paths over a plurality of arrays with one section per string in each array. A first set of strings to be brought online with the power converter is initialized. A drive signal is sent to switches in the initial set of strings to couple the sections in each string of the initial set so that the set of strings come online with the power converter providing voltage and current to the power converter.
대표청구항
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1. A photovoltaic system comprising: a first photovoltaic string and a second photovoltaic string, each of the photovoltaic strings is electrically coupled in parallel to each other between a positive rail and a negative rail and each of the photovoltaic strings includes a plurality of photovoltaic
1. A photovoltaic system comprising: a first photovoltaic string and a second photovoltaic string, each of the photovoltaic strings is electrically coupled in parallel to each other between a positive rail and a negative rail and each of the photovoltaic strings includes a plurality of photovoltaic panels;a first set of N distributed-array devices within the first photovoltaic string, the first set of N distributed-array devices arranged in series with the photovoltaic panels of the first string, and the first set of N distributed array devices, on demand, electrically decouples the first photovoltaic string into N+1 portions so as to break a current path between the positive and negative rails through the first photovoltaic string, wherein N is two or more;a second set of N distributed-array devices within the second photovoltaic string, the second set of N distributed-array devices arranged in series with the photovoltaic panels of the second string, and the second set of N distributed-array devices, on demand, electrically decouples the second photovoltaic string into N+1 portions so as to break a current path between the positive and negative rails through the second photovoltaic string; andat least one controller that controls the first and second sets of N distributed-array devices to electrically decouple the N+1 portions of each photovoltaic string during an idle period and to electrically couple the N+1 portions of each photovoltaic string during a start-up period, so that during the idle period the photovoltaic strings do not apply power between the positive and negative rails, and during a start-up period, the first set of distributed-array devices electrically couples the N+1 portions of the first photovoltaic string together before the second set of N distributed array devices couples the N+1 portions of the second photovoltaic string together so that the first photovoltaic string applies power to the positive and negative rails before the second photovoltaic string. 2. The photovoltaic system of claim 1, including a plurality of photovoltaic strings wherein: each of the photovoltaic strings including a corresponding set of N distributed-array devices, which on demand, separates each of the photovoltaic string into N+1 portions; andthe controller controls each of the sets of N distributed-array devices to electrically couple sequentially each set of N distributed array devices during the start-up period, so that each of the photovoltaic strings applies power to the positive and negative rails sequentially in time. 3. The photovoltaic system of claim 2 further comprising: a power conversion component electrically coupled between the positive rail and the negative rail converting the voltage and current from the each photovoltaic string and the second photovoltaic string to output voltage and current from the power conversion component; andthe power conversion component converting voltage and current from each of the first and section strings as the strings are sequentially, electrically coupled to the positive and negative rail so that power applied to the power conversion component increases without exceeding the power rating of the power conversion component as strings are coupled to the rails. 4. The photovoltaic system of claim 3 further comprising: N+1 photovoltaic arrays, each array including one portion of each photovoltaic string;each distributed-array device coupling one portion of each photovoltaic string on one array in series with a portion of the same string on another array whereby the photovoltaic strings are electrically coupled or decoupled in parallel from array to array by each string's corresponding set of distributed-array devices. 5. The photovoltaic system of claim 4 wherein the controller monitors the voltage and current at the power conversion component as strings are coupled to the rails and controls the sequentially coupling of the next string to the rails so that voltage and current at the power conversion component does not exceed the power rating for the power conversion component. 6. A photovoltaic system having a plurality of photovoltaic panels distributed over a plurality of arrays to provide a source of electrical power, said system comprising: a plurality of photovoltaic strings, each photovoltaic string having a plurality of photovoltaic panels in electrical series and each string extending across the plurality of arrays;each array having a portion of a string connected to another portion of the same string on another array by a tie connector;a switch in each tie connector to electrically couple and decouple the portions of the string;the portions of photovoltaic strings tie connected in parallel from array to array by the switches for each string and all strings connected to power rails collecting the power from all the strings;a power converter, electrically connected to the power rails, converting the power from each string as all portions of each string are electrically coupled by the switches for the string and the power from each string comes online to the power rails and thereby to the power converter; anda controller controlling the switches during system startup to electrically couple strings to the power rails in time sequence so that the power increases at the power converter without the power exceeding the power rating of the power converter as the strings come online. 7. The photovoltaic system of claim 6 wherein: the controller controls the switches during an idle mode to decouple all portions of all strings so that voltage on each portion of each string rises to a open circuit voltage for the portion. 8. The photovoltaic system of claim 7 wherein there are N switches per string and during idle mode each string is divided into N+1 portions. 9. The photovoltaic system of claim 8 wherein the controller controlling the switches for sets of strings during system startup to electrically couple sets of strings to the power rails in a time sequence, for each set of strings the controller simultaneously couples switches for K+1 strings as a set of strings from string SM to string SM+K, where M is the number of the first string in the setM+K is the number of the last string in the set andK is an integer number starting with zero (0),so that each string in a set comes online to the power converter simultaneously with all other strings in the set. 10. The photovoltaic system of claim 9 wherein the controller is responsive to power capacity information from the power converter to advance parameters M and K to specify the next set of strings to come online to the power converter so that the first string in the next set and the size of the next set maybe controlled. 11. The photovoltaic system of claim 6 wherein the tie connector includes at least one voltage sensor to sense a voltage at a terminal of the tie connector. 12. The photovoltaic system of claim 11 wherein the tie connector communicates a value of the voltage to the controller. 13. A photovoltaic system comprising: a plurality of parallel-arranged photovoltaic strings, each of the plurality of photovoltaic strings coupled between a positive rail and a negative rail and each of the plurality of strings including a plurality of photovoltaic panels;at least one distributed-array device within each of the photovoltaic strings, each of the distributed-array devices arranged in series with the photovoltaic panels of the corresponding photovoltaic string, each of the distributed array devices, on demand, switchably couples or decouples portions of each corresponding string so as to create or break a current path between the positive and negative rails through each corresponding string; andat least one controller that controls the distributed-array devices so that, during a start-up period, some of the distributed-array devices create current paths through some of the photovoltaic strings between the positive and negative rails before other distributed array devices create current paths through others of the photovoltaic strings between the positive and negative rails. 14. The photovoltaic system of claim 1, wherein the controller controls the distributed-array devices so that, during the start-up period, initially one string applies power to the positive and negative rails, then two strings apply power to the positive and negative rails until each of the plurality of strings applies power to the positive and negative rails. 15. A method for operating a photovoltaic system, the method comprising: operating each of a plurality of photovoltaic strings in parallel between conducting rails that are coupled to a power conversion component so that current paths are formed between the conducting rails, each of the photovoltaic strings including series-arranged photovoltaic panels, and within photovoltaic string, each of the series-arranged photovoltaic panels operates at a different voltage than other ones of the photovoltaic panels;separating each of the plurality of photovoltaic strings into a plurality of string sections so that, during an idle state, current does not flow between the rails through the photovoltaic strings; andcreating, during the idle state, a voltage overlap between the separated string sections in each of the photovoltaic strings so that, within each photovoltaic string, some voltages along one of the string sections are the same as some voltages along another one of the string sections. 16. The method of claim 15, wherein separating includes separating each of the plurality of photovoltaic strings into only two string sections so that, during an idle state, current does not flow between the rails through the photovoltaic strings; wherein creating, during the idle state, includes creating a voltage overlap between the two separated string sections in each of the photovoltaic strings so that, within each photovoltaic string, some voltages along one of the string sections are the same as some voltages along the other string section. 17. The method of claim 15, wherein separating includes separating each of the plurality of photovoltaic strings into three string sections so that, during an idle state, current does not flow between the rails through the photovoltaic strings; wherein creating, during the idle state, includes creating a voltage overlap between the three separated string sections in each of the photovoltaic strings so that, within each photovoltaic string, some voltages along each of the string sections are the same as some voltages along the other two string sections. 18. The method of claim 15, including: coupling together the strings sections in a subset of the photovoltaic strings to bring the subset of the photovoltaic strings online with the power conversion component, wherein coupling the subset reduces and extent of the voltage overlap;successively coupling together the string sections in other subsets of the photovoltaic strings, wherein the extent of the voltage overlap is reduced after each successive coupling until all the photovoltaic strings are brought online, and when all the photovoltaic strings are online, the voltage overlap does not exist. 19. A photovoltaic string coupling device including: a first terminal to couple to a first string section of a photovoltaic string;a second terminal to couple to a second string section of a photovoltaic string;a switch disposed between the first and second terminals so as to enable the first and second string sections of the photovoltaic string to be conductively coupled when the switch is closed; andmeans for creating a voltage overlap between the first and second string sections when the switch is opened so that some voltages along the first string section are the same as some voltages along the second string section.
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