CONTROL METHOD AND SYSTEM FOR PHOTOVOLTAIC INVERTERS WHOSE AC SIDES ARE CONNECTED IN PARALLEL
First Claim
1. A control method for photovoltaic inverters whose AC sides are connected in parallel, applied to a system in which AC sides of inverters are connected in parallel and DC sides of the inverters are independent from each other, wherein the system comprises at least two inverters which are a first inverter and a second inverter, wherein an input terminal of the first inverter is connected with a first PV array, an input terminal of the second inverter is connected with a second PV array, the first PV array and the second PV array each have a parasitic capacitance to ground, and the first inverter is coupled with the second PV array through the parasitic capacitances to form a common-mode loop;
- wherein the method comprises;
detecting a first direct voltage of the first inverter and a second direct voltage of the second inverter;
obtaining a difference between the first direct voltage and the second direct voltage; and
adjusting the direct voltages of the inverters to control the difference to be within a predetermined range and to control a common-mode voltage in the common-mode loop to be within a predetermined common-mode voltage range.
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Accused Products
Abstract
A control method and apparatus for photovoltaic inverters connected in parallel at an AC side are provided and the method includes the following steps: detecting a first direct voltage of the first inverter and a second direct voltage of the second inverter; obtaining a difference between the first direct voltage and the second direct voltage; and adjusting the direct voltages of the inverters to control the difference to be within a predetermined range and control a common-mode voltage in the common-mode loop to be within a predetermined common-mode voltage range.
14 Citations
10 Claims
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1. A control method for photovoltaic inverters whose AC sides are connected in parallel, applied to a system in which AC sides of inverters are connected in parallel and DC sides of the inverters are independent from each other, wherein the system comprises at least two inverters which are a first inverter and a second inverter, wherein an input terminal of the first inverter is connected with a first PV array, an input terminal of the second inverter is connected with a second PV array, the first PV array and the second PV array each have a parasitic capacitance to ground, and the first inverter is coupled with the second PV array through the parasitic capacitances to form a common-mode loop;
- wherein the method comprises;
detecting a first direct voltage of the first inverter and a second direct voltage of the second inverter; obtaining a difference between the first direct voltage and the second direct voltage; and adjusting the direct voltages of the inverters to control the difference to be within a predetermined range and to control a common-mode voltage in the common-mode loop to be within a predetermined common-mode voltage range. - View Dependent Claims (2, 3, 4)
- wherein the method comprises;
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5. A control apparatus for photovoltaic inverters whose AC sides are connected in parallel, comprising:
- a detection unit, a difference obtaining unit and a control unit, wherein
the detection unit is configured to detect a first direct voltage of the first inverter and a second direct voltage of the second inverter; the difference obtaining unit is configured to obtain a difference between the first direct voltage and the second direct voltage; and the control unit is configured to adjust the direct voltages of the inverters to control the difference to be within a predetermined range. - View Dependent Claims (6, 7)
- a detection unit, a difference obtaining unit and a control unit, wherein
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8. A photovoltaic inverter system in which AC sides of inverters are connected in parallel, comprising:
- at least two inverters which are a first inverter and a second inverter, wherein an input terminal of the first inverter is connected with a first PV array, an input terminal of the second inverter is connected with a second PV array, the first PV array and the second PV array each have a parasitic capacitance to ground, and the first inverter is coupled with the second inverter through the parasitic capacitances to form a common-mode loop;
wherein the AC side of the first inverter and the AC side of the second inverter are connected in parallel, and a DC side of the first inverter is independent from a DC side of the second inverter; wherein the first inverter functions as a host inverter, and the second inverter functions as a slave inverter; wherein the host inverter is configured to transmit a direct voltage of the host inverter to the slave inverter; wherein the slave inverter is configured to obtain a difference between the direct voltage of the host inverter and a direct voltage of the slave inverter, and adjust the direct voltage of the slave inverter to control the difference to be within a predetermined range and to control a common-mode voltage in the common-mode loop to be within a predetermined common-mode voltage range. - View Dependent Claims (9, 10)
- at least two inverters which are a first inverter and a second inverter, wherein an input terminal of the first inverter is connected with a first PV array, an input terminal of the second inverter is connected with a second PV array, the first PV array and the second PV array each have a parasitic capacitance to ground, and the first inverter is coupled with the second inverter through the parasitic capacitances to form a common-mode loop;
Specification