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Grid connection presynchronization control method of microgrid inverter based on droop control

A control method and inverter technology, applied in the direction of sustainable manufacturing/processing, single-network parallel feeding arrangement, climate sustainability, etc. Fundamentally suppress problems such as grid-connected current shocks, achieve simple and reliable judgment logic, improve rapidity and stability, and suppress current shocks

Inactive Publication Date: 2012-10-10
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS +1
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Problems solved by technology

Since the above method fails to realize the tracking synchronization between the inverter output voltage and the grid voltage, it cannot fundamentally suppress the grid-connected current impact

Method used

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  • Grid connection presynchronization control method of microgrid inverter based on droop control
  • Grid connection presynchronization control method of microgrid inverter based on droop control
  • Grid connection presynchronization control method of microgrid inverter based on droop control

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Embodiment Construction

[0029] Below in conjunction with accompanying drawing, the present invention is described in further detail:

[0030] The block diagram of the overall control structure of the three-phase microgrid inverter is as follows: figure 1 As shown, the main symbol name of the main circuit: (1) U dc - Input DC voltage. (2)C a , C b , C c - Three-phase filter capacitor. (3) L a , L b , L c ——Three-phase filter inductor. (4) L ga , L gb , L gc ——The inductance on the grid side is mainly composed of the line inductance and the equivalent inductance of the transformer. The output terminal of the three-phase inverter is connected to the microgrid feeder, and the microgrid is connected to the large power grid through the point of common connection (PCC). In order to realize the smooth switching of the microgrid from the island mode to the grid-connected mode, a grid-connected pre-synchronization control unit is added on the basis of the original droop control. The droop control...

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Abstract

The invention relates to a grid connection presynchronization control method of a microgrid inverter based on droop control. When the microgrid operates in island, as a voltage source type inverter which functions as the support in the microgrid works in accordance with droop characteristic, a microgrid voltage has a deviation from a high power grid voltage; and the problem of synchronization between the microgrid voltage and the high power grid voltage during the grid connection is the key to realize smooth switchover. The grid connection presynchronization control method provided by the invention comprises the following steps: obtaining frequency and phase position information of the high power grid voltage through a three phase software phase-locked loop (SPLL); carrying out dq (Direct Quadrate) conversion to an output voltage of the inverter based on a power grid voltage phase obtained from the locked phase; subsequently carrying out PI (Physical Impairment) regulation on a q-axis component; overlapping a synchronization angle frequency output by a PI regulator with an angle frequency generated by the droop control to be used as a reference angle frequency of the output voltage of the inverter; and finally realizing the tracking and synchronization of the output voltage of the microgrid inverter to the high power grid voltage through the closed-loop control. The impact current during the grid connection is avoided effectively.

Description

technical field [0001] The invention relates to a grid-connected pre-synchronization control method of a micro-grid inverter based on droop control, which belongs to the micro-grid inverter control technology in the power conversion technology. Background technique [0002] It is an effective way to realize the large-scale application of distributed power generation by connecting distributed power generation to the large power grid in the form of a micro-grid. There are two typical operation modes of grid-connected and islanded microgrids. When the microgrid is in the grid-connected mode, the large grid provides rigid voltage and frequency support; when the large grid fails or the power quality does not meet the load requirements, the microgrid Disconnect the connection with the large power grid and switch to the island operation mode. At this time, the internal voltage and frequency of the microgrid lose the support of the large power grid, and the micro power supply inside...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/40
CPCY02P80/14
Inventor 张中锋陈新
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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