Pre-charging control method and system for five-level photovoltaic inverter

A photovoltaic inverter, five-level technology, applied in photovoltaic power generation, electrical components, circuit devices, etc., can solve problems such as the failure of five-level photovoltaic inverter to start normally, affecting the reliable operation of photovoltaic grid-connected power generation systems, etc.

Active Publication Date: 2015-03-25
SUNGROW POWER SUPPLY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In view of this, the present invention provides a five-level photovoltaic inverter pre-charging control method and system, which solves the problem that the five-level photovoltaic inverter cannot be started normally due to the high DC bus capacitor voltage in the prior art. Technical problems that affect the reliable operation of photovoltaic grid-connected power generation systems

Method used

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  • Pre-charging control method and system for five-level photovoltaic inverter
  • Pre-charging control method and system for five-level photovoltaic inverter
  • Pre-charging control method and system for five-level photovoltaic inverter

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Embodiment 1

[0043] refer to figure 2 Shown is a schematic flow chart of a five-level photovoltaic inverter pre-charging control method according to the present invention. In this embodiment, the method may specifically include the following steps:

[0044] Step S11: When the grid precharges the DC bus capacitor of the five-level photovoltaic inverter through the precharging circuit, detect the current voltage of the DC bus capacitor in real time.

[0045] In the practical application of photovoltaic grid-connected power generation systems, in order to prevent the impact of the grid on the photovoltaic inverter to be connected to the grid, the DC bus capacitor of the photovoltaic inverter is usually pre-charged before starting the photovoltaic inverter.

[0046] Among them, in order to grasp the changes of the grid voltage and the DC bus voltage in real time, in the practical application of this embodiment, the peak value of the grid voltage and the DC bus voltage can be detected in real ...

Embodiment 2

[0060] refer to Figure 4 The schematic flow chart of another five-level photovoltaic inverter pre-charging control method of the present invention is shown, wherein, the topology diagram of the five-level photovoltaic inverter can refer to figure 1 , this embodiment will not be described in detail here, then the control method may include the following steps:

[0061] Step S21: When the grid precharges the DC bus capacitor of the five-level photovoltaic inverter through the precharging circuit, detect the current voltage of the DC bus capacitor and the grid voltage peak value in real time.

[0062] Step S22: When the detected current voltage of the DC bus capacitor is equal to the peak value of the grid voltage, disconnect the pre-charging circuit.

[0063] Step S23: Determine whether the current voltage of the DC bus capacitor detected when the pre-charging circuit is disconnected is less than the first threshold value, if not, go to step S24, and if yes, go to step S26.

...

Embodiment 3

[0070] refer to Figure 4 Shown is a schematic structural diagram of a five-level photovoltaic inverter pre-charging control system of the present invention, wherein the five-level photovoltaic inverter may include a first DC / DC circuit, a second DC / DC circuit, a DC bus Capacitor and five-level inverter unit, its specific connection structure and its connection relationship with other devices in the photovoltaic grid-connected power generation system can refer to figure 1 , this embodiment will not be repeated here, then the pre-charging control system may specifically include: a detection device 31, a first controller 32 and a second controller 33, wherein:

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Abstract

The invention provides a pre-charging control method and system for a five-level photovoltaic inverter. When a power grid conducts pre-charging on a direct-current bus capacitor, the current voltage of the direct-current bus capacitor is detected in real time, when pre-charging conditions are met, a pre-charging circuit is switched off, if the voltage of the direct-current bus capacitor is not smaller than a first threshold value at the monument, the five-level photovoltaic inverter is controlled to work in a three-level work mode so as to reduce the voltage of the direct-current bus capacitor, and when the reduced current voltage of the direct-current bus capacitor reaches a second threshold value, the five-level photovoltaic inverter is controlled to quit the three-level work mode and operate in a normal grid-connected work mode; in this way, the condition that the voltage of the direct-current bus capacitor is larger than the maximum protective voltage of the direct-current bus capacitor is avoided, the normal start of the five-level photovoltaic inverter is guaranteed, and reliable operation of a photovoltaic grid-connected power generation system is guaranteed.

Description

technical field [0001] The present invention mainly relates to the control field of photovoltaic grid-connected power generation systems, and more specifically relates to a five-level photovoltaic inverter pre-charging control method and system. Background technique [0002] Photovoltaic inverter is an important part of photovoltaic grid-connected power generation system. It is used to convert the direct current generated by PV panels into alternating current and then transmit it to the grid. In practical applications, in order to improve inverter efficiency and reduce harmonics, usually Multi-level photovoltaic inverters can be used to connect to the grid. This invention aims at improving the grid-connected work of five-level photovoltaic inverters. Before the five-level photovoltaic inverters are connected to the grid, in order to prevent the five-level photovoltaic inverters from When the inverter is connected to the grid, the power grid will have a great impact on it, wh...

Claims

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Application Information

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IPC IPC(8): H02J3/38H02M1/36
CPCH02J3/383H02M1/36Y02E10/56
Inventor 张成丁杰邹海晏陶磊徐涛涛
Owner SUNGROW POWER SUPPLY CO LTD
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