Centralized MPPT exiting and switching method and application thereof
First Claim
1. A method for exiting a Maximum Power Point Tracking (MPPT) centralized mode of a photovoltaic inverter, wherein the photovoltaic inverter comprises a plurality of direct current (DC) chopper circuits and an inverting circuit, the inverting circuit is connected to an output side of the plurality of DC chopper circuits on which side the plurality of DC chopper circuits are connected in parallel to a DC bus, and a plurality of photovoltaic strings are connected in parallel to the DC bus via the plurality of DC chopper circuits, the method comprising:
- obtaining a maximum power point for each of the plurality of photovoltaic strings, by performing a MPPT control individually on each of the plurality of photovoltaic strings in response to the photovoltaic inverter operating in the MPPT centralized mode and in response to the plurality of DC chopper circuits which are stopped from operating;
determining output voltages of the plurality of photovoltaic strings, which correspond to the obtained maximum power points;
determining one of the plurality of photovoltaic strings having a standard voltage value, which is a maximum or minimum one among the determined output voltages of the plurality of photovoltaic strings according to a type of the plurality of DC chopper circuits;
determining whether a voltage difference between the output voltage of a further one of the plurality of photovoltaic strings and the standard voltage value of the one of the plurality of photovoltaic strings exceeds a preset voltage difference; and
restarting the DC chopper circuit connected to the further one of the plurality of photovoltaic strings in response to the determined voltage difference exceeding the preset voltage difference.
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Accused Products
Abstract
Disclosed is a centralized MPPT exiting method for a photovoltaic inverter comprising multiple DC chopper circuits and one inverter circuit. The method comprises: when the photovoltaic inverter is in a centralized MPPT mode, MPPT control is implemented independently for each photovoltaic cell in a photovoltaic component and the maximum power point for each photovoltaic cell is obtained; a reference value of the maximum power point for each photovoltaic cell is determined according to the type of the multiple DC chopper circuits; whether the voltage difference between the other maximum power points and the reference value goes beyond an allowable voltage difference is judged and the operation of the DC chopper circuits connecting to the photovoltaic cells with a voltage difference beyond the allowable voltage difference is recovered.
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Citations
19 Claims
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1. A method for exiting a Maximum Power Point Tracking (MPPT) centralized mode of a photovoltaic inverter, wherein the photovoltaic inverter comprises a plurality of direct current (DC) chopper circuits and an inverting circuit, the inverting circuit is connected to an output side of the plurality of DC chopper circuits on which side the plurality of DC chopper circuits are connected in parallel to a DC bus, and a plurality of photovoltaic strings are connected in parallel to the DC bus via the plurality of DC chopper circuits, the method comprising:
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obtaining a maximum power point for each of the plurality of photovoltaic strings, by performing a MPPT control individually on each of the plurality of photovoltaic strings in response to the photovoltaic inverter operating in the MPPT centralized mode and in response to the plurality of DC chopper circuits which are stopped from operating; determining output voltages of the plurality of photovoltaic strings, which correspond to the obtained maximum power points; determining one of the plurality of photovoltaic strings having a standard voltage value, which is a maximum or minimum one among the determined output voltages of the plurality of photovoltaic strings according to a type of the plurality of DC chopper circuits; determining whether a voltage difference between the output voltage of a further one of the plurality of photovoltaic strings and the standard voltage value of the one of the plurality of photovoltaic strings exceeds a preset voltage difference; and restarting the DC chopper circuit connected to the further one of the plurality of photovoltaic strings in response to the determined voltage difference exceeding the preset voltage difference. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An apparatus for exiting a Maximum Power Point Tracking (MPPT) centralized mode of a photovoltaic inverter, wherein the photovoltaic inverter comprises a plurality of direct current (DC) chopper circuits and an inverting circuit, the inverting circuit is connected to an output side of the plurality of DC chopper circuits on which side the plurality of DC chopper circuits are connected in parallel to a DC bus, and a plurality of photovoltaic strings are connected in parallel to the DC bus via the plurality of DC chopper circuits, the apparatus comprising:
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a maximum power point determination unit, configured to obtain a maximum power point for each of the plurality of photovoltaic strings by performing a MPPT control individually on each of the plurality of photovoltaic strings in response to the photovoltaic inverter operating in the MPPT centralized mode and in response to the plurality of DC chopper circuits which are stopped from operating; a standard value determination unit connected with the maximum power point determination unit, configured to determine output voltages of the plurality of photovoltaic strings, which correspond to the obtained maximum power points, and determine one of the plurality of photovoltaic strings having a standard voltage value, which is a maximum or minimum one among the determined output voltages of the plurality of photovoltaic strings according to a type of the plurality of DC chopper circuits; and a circuit restarting unit connected with the standard value determination unit, configured to determine whether a voltage difference between the output voltage of a further one of the plurality of photovoltaic strings and the standard voltage value of the one of the plurality of photovoltaic strings exceeds a preset voltage difference, and restart the DC chopper circuit connected to the further one of the plurality of photovoltaic strings in response to the determined voltage difference exceeding the preset voltage difference. - View Dependent Claims (18)
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19. An inverter control system for a photovoltaic inverter, wherein the photovoltaic inverter comprises a plurality of direct current (DC) chopper circuits and an inverting circuit, the inverting circuit is connected to an output side of the plurality of DC chopper circuits on which side the plurality of DC chopper circuits are connected in parallel to a DC bus, and a plurality of photovoltaic strings are connected in parallel to the DC bus via the plurality of DC chopper circuits, wherein, the control system is configured to:
in response to the photovoltaic inverter operating in a MPPT centralized mode and in response to the plurality of DC chopper circuits which are stopped from operating, obtain a maximum power point for each of the plurality of photovoltaic strings, by performing a MPPT control individually on each of the plurality of photovoltaic strings;
determine output voltages of the plurality of photovoltaic strings, which correspond to the obtained maximum power points;
determine one of the plurality of photovoltaic strings having a standard voltage value, which is a maximum or minimum one among the determined output voltages of the plurality of photovoltaic strings according to a type of the plurality of DC chopper circuits;
determine whether a voltage difference between the output voltage of a further one of the plurality of photovoltaic strings and the standard voltage value of the one of the plurality of photovoltaic strings exceeds a preset voltage difference, and restart the DC chopper circuit connected to the further one of the plurality of photovoltaic strings in response to the determined voltage difference exceeding the preset voltage difference.
Specification