Safety mechanisms, wake up and shutdown methods in distributed power installations
地域：
Herzliya Pituah
摘要
A distributed power system including multiple DC power sources and multiple power modules. The power modules include inputs coupled respectively to the DC power sources and outputs coupled in series to form a serial string. An inverter is coupled to the serial string. The inverter converts power input from the serial string to output power. A signaling mechanism between the inverter and the power module is adapted for controlling operation of the power modules. Also, for a protection method in the distributed power system, when the inverter stops production of the output power, each of the power modules is shut down and thereby the power input to the inverter is ceased.
說明書
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The present application is a continuation-in-part of U.S. application Ser. No. 13/372,009, filed Feb. 13, 2012, which is a continuation of U.S. application Ser. No. 12/329,525, filed Dec. 5, 2008, which claims the benefit of U.S. Provisional Application Ser. No. 60/992,589, filed Dec. 5, 2007. U.S. application Ser. No. 12/329,525, filed Dec. 5, 2008 is a continuation-in-part of U.S. application Ser. No. 11/950,271, filed Dec. 4, 2007, which claims the benefit of each of U.S. Provisional Application Ser. No. 60/916,815, filed May 9, 2007, U.S. Provisional Application Ser. No. 60/908,095, filed Mar. 26, 2007, U.S. Provisional Application No. 60/868,962, filed Dec. 7, 2006, U.S. Provisional Application No. 60/868,851, filed Dec. 6, 2006, and U.S. Provisional Application No. 60/868,893, filed Dec. 6, 2006. The present application also is a continuation-in-part of U.S. application Ser. No. 14/323,531, filed Jul. 3, 2014, which is a continuation of U.S. application Ser. No. 12/328,742, filed Dec. 4, 2008, which is a continuation-in-part of U.S. application Ser. No. 11/950,271, filed Dec. 4, 2007. Each of the above-mentioned disclosures are incorporated herein by reference in its entirety and for all purposes.
The present invention relates to distributed power systems and, more particularly, wake-up and shutdown algorithms for the photovoltaic distributed power systems. The present invention also relates to anti-islanding in a distributed power system and, more particularly, system and method for protection of photovoltaic distributed power equipment and personnel during anti-islanding.
權(quán)利要求
The invention claimed is:1. A method comprising:receiving power from a direct current (DC) power source at an input of a power converter; controlling, with a controller comprising a digital pulse width modulator, the power converter by adjusting a duty cycle of the power converter using pulse width modulation, wherein the controlling includes:operating the power converter at a low duty cycle to limit output voltage at an output of the power converter below a predetermined voltage in response to detecting an absence of a communication signal; detecting, while limiting the output voltage, receipt of the communication signal; responsive to detecting receipt of the communication signal, performing an iterative voltage control process including multiple iterations of:operating the power converter to increase the output voltage by increasing the duty cycle of the power converter, and detecting an amount of current being drawn, from the output of the power converter, by an inverter, wherein in one iteration of the voltage control process, the detected amount of current being drawn exceeds a preexisting level; responsive to the increases of the output voltage and responsive to the controller detecting the amount of current being drawn by the inverter exceeds the preexisting level, the controller transitioning the power converter from the iterative voltage control process to maximum power point tracking; and maintaining, by the controller and responsive to the transitioning, the output voltage to be below a maximum output voltage of the power converter while simultaneously maintaining about maximum power at the input of the power converter. 2. The method of claim 1 , wherein the DC power source comprises one or more solar cells. 3. The method of claim 1 , wherein the power converter comprises a direct current to direct current (DC/DC) converter. 4. The method of claim 1 , wherein the detecting of the receipt of the communication signal comprises receiving the communication signal from a signaling mechanism associated with the inverter. 5. The method of claim 1 , wherein the detecting of the receipt of the communication signal comprises determining that the communication signal comprises a 60 Hz grid frequency. 6. The method of claim 1 , wherein the detecting of the receipt of the communication signal comprises determining that the communication signal comprises a predetermined frequency corresponding to an output of the inverter. 7. The method of claim 1 , wherein the detecting of the receipt of the communication signal comprises detecting the communication signal received on an electrical conductor from the inverter. 8. The method of claim 1 , wherein the detecting of the receipt of the communication signal comprises detecting a wireless signal. 9. The method of claim 1 , further comprising:producing, by the power converter, the output voltage at the output of the power converter that is lower than an input voltage at the input of the power converter. 10. The method of claim 9 , wherein the power converter includes a buck converter and the method further comprising:producing the output voltage using the buck converter. 11. The method of claim 1 , further comprising:receiving the communication signal using a power line communication. 12. The method of claim 1 , further comprising:generating the communication signal in response to a change in voltage, current, or power corresponding to an inverter or a power grid. 13. The method of claim 12 , wherein the change comprises one or more of the voltage, the current, or the power corresponding to the inverter or the power grid, falling out of a predetermined range. 14. The method of claim 1 , further comprising:ceasing generation of the communication signal in response to an islanding condition. 15. The method of claim 1 , wherein operating the power converter at the low duty cycle to limit the output voltage at the output of the power converter below the predetermined voltage comprises limiting the output voltage to a non-zero voltage. 16. The method of claim 1 , wherein the communication signal uses frequency shift keying (FSK) modulation. 17. The method of claim 1 , further comprising:ceasing to output power by the power converter in response to detecting a change in the receipt of the communication signal. 18. The method of claim 1 , wherein the detecting the amount of current being drawn by the inverter includes:after a first increase of the output voltage, determining that the amount of current being drawn in is not at a first level enabling performance of maximum power point tracking; and after the first increase and after a second increase of the output voltage, determining that the amount of current being drawn in is above the first level. 19. The method of claim 1 , wherein the controller is a microcontroller comprising the digital pulse width modulator. 20. An apparatus comprising:a power converter comprising input terminals, output terminals, and a controller, wherein the power converter is configured to be powered on using direct current (DC) power received at the input terminals, and wherein the controller comprises a digital pulse width modulator and is configured to control the power converter by adjusting a duty cycle of the power converter using pulse width modulation, wherein the controller is further configured to:operate the power converter at a low duty cycle to limit output voltage at the output terminals of the power converter below a predetermined voltage in response to detecting an absence of a communication signal; detect, while limiting the output voltage, receipt of the communication signal; responsive to detecting receipt of the communication signal, perform an iterative voltage control process including multiple iterations of:a first operation to control the power converter to increase the output voltage by increasing the duty cycle of the power converter, and a second operation by the controller to determine an amount of current being drawn, from the output terminals of the power converter, by an inverter; responsive to the increases of the output voltage and responsive to the controller determining the amount of current being drawn by the inverter exceeds a preexisting level, transition the power converter from the iterative voltage control process to maximum power point tracking; and maintain, responsive to the transitioning, the output voltage to be below a maximum output voltage of the power converter while simultaneously maintaining about maximum DC power at the input terminals of the power converter. 21. The apparatus of claim 20 , wherein the power converter comprises a switch configured to stop a flow of power from the input terminals to the output terminals. 22. The apparatus of claim 20 , wherein the power converter comprises a direct current to direct current (DC/DC) converter or a direct current to alternating current (DC/AC) converter. 23. The apparatus of claim 20 , wherein the controller is further configured to determine that the communication signal comprises a frequency corresponding to an output of the inverter. 24. The apparatus of claim 20 , wherein the controller is further configured to determine whether the communication signal has been received from a signaling mechanism. 25. The apparatus of claim 20 , further comprising the inverter, wherein the output terminals are coupled to the inverter. 26. The apparatus of claim 20 , wherein the controller is further configured to operate the power converter at the low duty cycle to limit output voltage at the output of the power converter to a non-zero voltage. 27. The apparatus of claim 20 , wherein the communication signal uses frequency shift keying (FSK) modulation. 28. The apparatus of claim 20 , wherein the second operation to determine the amount of current being drawn by the inverter comprises:after a first increase of the output voltage, determining that the amount of current being drawn is not at a first level enabling performance of maximum power point tracking; and after the first increase and after a second increase of the output voltage, determining that the amount of current being drawn is at the first level. 29. The apparatus of claim 20 , wherein the controller is a microcontroller comprising the digital pulse width modulator.
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