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A method and system for starting parallel inverters

A technology for starting systems and inverters, applied in output power conversion devices, photovoltaic power generation, electrical components, etc., can solve problems such as inconsistent start-up and grid-connection times of parallel inverters, and achieve the effect of reducing circulating currents

Active Publication Date: 2017-02-22
SUNGROW POWER SUPPLY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] The technical problem to be solved by the present invention is to provide a start-up method and system for parallel inverters, which can solve the problem of circulating current caused by the inconsistent start-up time of each parallel inverter when multiple inverters are connected in parallel

Method used

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  • A method and system for starting parallel inverters
  • A method and system for starting parallel inverters
  • A method and system for starting parallel inverters

Examples

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Embodiment 1

[0048] see image 3, which is a flow chart of Embodiment 1 of the method for starting parallel inverters provided by the present invention.

[0049] The method for starting a parallel inverter provided in this embodiment is applicable to a system in which at least two inverters are connected in parallel, the AC side of the inverter is connected in parallel, and the DC side is independent; it includes the following steps:

[0050] S301: The running inverter receives the startup instruction sent by the inverter to be started, and sends a control instruction when its own DC voltage rises to the open circuit voltage of the connected PV array or the upper voltage limit of the maximum power point tracking MPPT giving the to-be-started inverter a start-up operation;

[0051] It should be noted that, when the open-circuit voltage is equal to the upper voltage limit of the MPPT, the running inverter raises its own DC voltage to the open-circuit voltage of the PV array. When the upper...

Embodiment 2

[0068] see Figure 5 , which is a flow chart of Embodiment 2 of the method for starting parallel inverters provided by the present invention.

[0069] It should be noted that the method embodiments correspond to the case where the AC sides of the inverters are connected in parallel and the DC sides are independent. However, in this embodiment, the AC side of the inverter is connected in parallel, and the DC side is also connected in parallel.

[0070] It can be understood that for the inverter system in which the AC side is connected in parallel and the DC side is also connected in parallel, it is divided into a master inverter and a slave inverter. Only the master inverter performs MPPT control, and the slave inverter follows the master inverter. working. Therefore, in the method of this embodiment, the host completes the scanning process.

[0071] The method for starting a parallel inverter provided in this embodiment is applicable to a system in which at least two invert...

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Abstract

The invention provides a parallel inverter starting method which is suitable for a system in which at least two inverters are connected in parallel. The alternating current sides of the inverters are connected in parallel, and the direct current sides are independent to one another. The parallel inverter starting method includes the steps that operating inverters receive start commands sent by inverters to be started, when the direct current voltage of the operating inverters rises to open-circuit voltage of a PV array connected with the operating inverters or the voltage upper limit values of the maximum power point track (MPPT), control commands are sent to the inverters to be started to start and operate the inverters to be started; all the inverters conduct direct current voltage scanning jointly from the open-circuit voltage or the voltage upper limit value of the MPPT till the MPPT voltage lower limit values corresponding to all the inverters are scanned, and the maximum power points corresponding to all the inverters in the scanning process are recorded; all the inverters operate to the maximum power points corresponding to all the inverters from the MPPT voltage lower limit values corresponding to all the inverters. At the positions where the output powers of the operating inverters are approximate to zero, the inverters to be started are controlled to be started, and ring current caused by different powers among the inverters is reduced.

Description

technical field [0001] The invention relates to the technical field of photovoltaic power generation, in particular to a starting method and system for parallel inverters. Background technique [0002] With the continuous expansion of the capacity of new energy power stations, in order to realize the optimal allocation of grid-connected inverter capacity and realize the single-machine WM-level solution, the parallel connection of inverters has become a trend of technological development. [0003] Some parallel inverters are connected in parallel on the AC side and independent on the DC side (that is, not connected in parallel). Its advantage is that it supports multi-channel inverters to independently perform maximum power point tracking MPPT. There are also parallel inverters in which both the AC side and the DC side are connected in parallel. The advantage is that it can easily realize the group control strategy, thereby improving the overall efficiency of the parallel sys...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M1/36
CPCY02E10/56
Inventor 程林潘年安王志成陶磊
Owner SUNGROW POWER SUPPLY CO LTD