Photovoltaic inverter and power-on self-testing method thereof

Abstract

The invention discloses a photovoltaic inverter and a power-on self-testing method of the photovoltaic inverter. The power-on self-testing method includes the steps that a direct-current-side on-off control module is added on the direct-current side of the photovoltaic inverter, wherein the direct-current-side on-off control module comprises a soft start on-off element, a soft start resistor, a partial voltage on-off element and a partial voltage resistor, the soft start on-off element and the soft start resistor are connected in series, and the partial voltage on-off element and the partial voltage resistor are connected in series; when the soft start on-off element and the partial voltage on-off element are closed, the soft start resistor is connected with the partial voltage resistor in series, a main on-off element and an alternating-current on-off element of the photovoltaic inverter are controlled to be kept in an off state, the main on-off element is located on the direct-current side of the photovoltaic inverter, and the alternating-current on-off element is located between an inverter bridge of the photovoltaic inverter and a power grid. Through the partial voltage resistor, input voltage is kept in a low-voltage and low-current state, so that due to the low voltage and the low current, even if the inverter bridge has short circuit or other faults, the inverter bridge does not explode with a big sound.

Description

technical field

[0001] The invention relates to the technical field of photovoltaic inverters, in particular to a photovoltaic inverter and a power-on self-inspection method thereof. Background technique

[0002] Due to the complex environment of the power generation site and the environmental conditions of the power grid, the photovoltaic inverter may burst when it is turned on and inverting, and it will make a loud explosion sound. Under normal circumstances, as long as the inverter bridge, the core component of the photovoltaic inverter, does not have any problems, the inverter will not explode. Therefore, if the fault self-test of the inverter bridge part can be performed before the inverter is turned on, the bombing can be avoided. The inverter bridge is usually constructed by IGBT (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor) modules or discrete devices. The IGBT module generally comes with a CE detection signal, which is used to judge whethe...

Examples

Embodiment 1

[0027] This embodiment provides a photovoltaic inverter, the first and second input terminals of which are respectively connected to the positive pole and negative pole (PV+ and PV- in the illustration) of a photovoltaic array formed by connecting together a plurality of photovoltaic cells , the output terminal is connected to the grid. Such as figure 1 As shown, the photovoltaic inverter includes an input capacitor branch, an inverter bridge circuit 101 , a control module 102 and a disconnection module connected in sequence. Wherein, the input capacitor branch includes BUS capacitors C1 and C2, which provide energy support for the inverter bridge circuit 101 and are the input voltage for the normal operation of the inverter bridge circuit 101; frequency, same-phase AC current, and feed it to the grid to realize photovoltaic grid-connected power generation; the control module 102 generally uses a single-chip microcomputer or a digital signal processor (DSP) chip as a control ...

Embodiment 2

[0038] The photovoltaic inverter provided in this embodiment is the same as that in Embodiment 1, but the difference from Embodiment 1 during power-on self-check is that the voltage of the input capacitor branch obtained by sampling is also judged to determine whether it is equal to the first reference voltage, If it is not equal, it is determined that the inverter bridge of the photovoltaic inverter is faulty, and if it is equal, the power-on self-test is ended. Specifically, through the power-on self-test of Embodiment 1, it is in a low-voltage and low-current state at this time, and then the first reference voltage V can be calculated by the control module 102 in , its calculation formula is

[0039] V in =V pv ×[R 2 ÷(R 1 +R 2 )] (1)

[0040] Among them, V pv Enter the real-time voltage value of the positive and negative terminals for the solar cell voltage.

[0041] The sampling voltage V can be obtained through the voltage samp...

Embodiment 3

[0052] The difference between this embodiment and Embodiment 2 is that, after judging that the voltage of the input capacitor branch obtained by sampling is equal to the first reference voltage, instead of directly ending the power-on self-test, the inverter voltage is detected to determine the voltage of the inverter bridge. Is there a fault. Specifically, the control module 102 sends a pulse width modulation (PWM) signal to invert the inverter bridge, samples the inverter voltage, and judges whether the inverter voltage is equal to the second reference voltage, and if not, determines that the inverter bridge is faulty. If equal, the control module stops sending PWM signals, disconnects the soft-start on-off element K2 and the voltage-dividing on-off element K3, and ends the power-on self-test.

[0053] This embodiment takes three-phase three-wire grid voltage sampling as an example, that is, BC-phase grid voltage V1, CA-phase grid voltage V2, and AB-phase grid voltage V3. V...

technical field

[0001] The invention relates to the technical field of photovoltaic inverters, in particular to a photovoltaic inverter and a power-on self-inspection method thereof. Background technique

[0002] Due to the complex environment of the power generation site and the environmental conditions of the power grid, the photovoltaic inverter may burst when it is turned on and inverting, and it will make a loud explosion sound. Under normal circumstances, as long as the inverter bridge, the core component of the photovoltaic inverter, does not have any problems, the inverter will not explode. Therefore, if the fault self-test of the inverter bridge part can be performed before the inverter is turned on, the bombing can be avoided. The inverter bridge is usually constructed by IGBT (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor) modules or discrete devices. The IGBT module generally comes with a CE detection signal, which is used to judge whethe...

Examples

Embodiment 1

[0027] This embodiment provides a photovoltaic inverter, the first and second input terminals of which are respectively connected to the positive pole and negative pole (PV+ and PV- in the illustration) of a photovoltaic array formed by connecting together a plurality of photovoltaic cells , the output terminal is connected to the grid. Such as figure 1 As shown, the photovoltaic inverter includes an input capacitor branch, an inverter bridge circuit 101 , a control module 102 and a disconnection module connected in sequence. Wherein, the input capacitor branch includes BUS capacitors C1 and C2, which provide energy support for the inverter bridge circuit 101 and are the input voltage for the normal operation of the inverter bridge circuit 101; frequency, same-phase AC current, and feed it to the grid to realize photovoltaic grid-connected power generation; the control module 102 generally uses a single-chip microcomputer or a digital signal processor (DSP) chip as a control ...

Embodiment 2

[0038] The photovoltaic inverter provided in this embodiment is the same as that in Embodiment 1, but the difference from Embodiment 1 during power-on self-check is that the voltage of the input capacitor branch obtained by sampling is also judged to determine whether it is equal to the first reference voltage, If it is not equal, it is determined that the inverter bridge of the photovoltaic inverter is faulty, and if it is equal, the power-on self-test is ended. Specifically, through the power-on self-test of Embodiment 1, it is in a low-voltage and low-current state at this time, and then the first reference voltage V can be calculated by the control module 102 in , its calculation formula is

[0039] V in =V pv ×[R 2 ÷(R 1 +R 2 )] (1)

[0040] Among them, V pv Enter the real-time voltage value of the positive and negative terminals for the solar cell voltage.

[0041] The sampling voltage V can be obtained through the voltage samp...

Embodiment 3

[0052] The difference between this embodiment and Embodiment 2 is that, after judging that the voltage of the input capacitor branch obtained by sampling is equal to the first reference voltage, instead of directly ending the power-on self-test, the inverter voltage is detected to determine the voltage of the inverter bridge. Is there a fault. Specifically, the control module 102 sends a pulse width modulation (PWM) signal to invert the inverter bridge, samples the inverter voltage, and judges whether the inverter voltage is equal to the second reference voltage, and if not, determines that the inverter bridge is faulty. If equal, the control module stops sending PWM signals, disconnects the soft-start on-off element K2 and the voltage-dividing on-off element K3, and ends the power-on self-test.

[0053] This embodiment takes three-phase three-wire grid voltage sampling as an example, that is, BC-phase grid voltage V1, CA-phase grid voltage V2, and AB-phase grid voltage V3. V...

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