Direct-current microgrid island detection method based on MPPT trapezoidal voltage disturbance

A DC micro-grid and island detection technology, which is applied in parallel operation of DC power supplies, DC network circuit devices, photovoltaic system monitoring, etc., can solve problems such as large detection blind spots, and achieve small impact on power quality, guarantee effectiveness, and small range Effect

Active Publication Date: 2020-10-30
TIANJIN UNIV
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Problems solved by technology

In the DC microgrid, only the electrical quantity of the voltage signal can be used. Compared with the AC microgrid, the passive method detection blind area of ​​the DC microgrid is larger

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  • Direct-current microgrid island detection method based on MPPT trapezoidal voltage disturbance
  • Direct-current microgrid island detection method based on MPPT trapezoidal voltage disturbance
  • Direct-current microgrid island detection method based on MPPT trapezoidal voltage disturbance

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Embodiment Construction

[0045] The technical solution will be described in detail below with reference to the accompanying drawings.

[0046] In the present invention, by making appropriate changes to the MPPT strategy, the output power of the PVA fluctuates according to the periodic trapezoidal signal near the maximum power, thereby causing the PCC voltage to fluctuate periodically after the islanding occurs. Theoretical analysis determines that islanding occurs in the DC microgrid. Moreover, when multiple PVAs in the same area supply power to the load at the same time, considering that the disturbances imposed by different PVAs may cancel each other and thus reduce the accuracy of islanding detection, the invention proposes a disturbance synchronization scheme to ensure the reliability of islanding detection.

[0047] The DC micro-grid island detection method based on MPPT trapezoidal voltage disturbance of the present invention comprises steps:

[0048] Step 1, start the MPPT strategy, and set th...

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Abstract

The invention discloses a DC (direct-current) microgrid island detection method based on MPPT trapezoidal voltage disturbance. The method comprises the following steps: starting an MPPT strategy; setting a starting signal threshold value of disturbance; measuring an output current value when PVA operates at the maximum power, calculating the same environment coefficients of PVA with different capacities under the same illumination intensity and temperature in real time, and when the environment coefficients are greater than a set disturbance starting signal threshold value, controlling to carry out periodic trapezoidal disturbance on a PVA port voltage reference value; when it is detected that the PCC voltage value Upcc exceeds a threshold value set through a passive method, judging that an island exists, and otherwise, judging whether the change rule of the Upcc is consistent with the change rule of the calculated value Upccp of the PCC voltage under trapezoidal disturbance or not; and if so, determining that the island exists, otherwise, determining that the island is a pseudo-island. Active and passive modes are combined to carry out direct-current island detection and are matched with each other, so that no detection blind area exists.

Description

technical field [0001] The invention belongs to the technical field of power system protection and control, and relates to a DC micro-grid island detection method based on MPPT trapezoidal voltage disturbance, which is suitable for distributed generation (Distributed Generation, DG) containing multiple photovoltaic power generation systems. Background technique [0002] New energy power supply and grid power supply complement and coordinate each other, which is an ideal way to comprehensively utilize existing energy to provide users with reliable and high-quality electric energy. As an important part of the new energy power supply system, photovoltaic power generation has achieved considerable development due to its advantages of no noise, no pollution, and no geographical restrictions. In a microgrid equipped with a photovoltaic power generation system DG, when the grid stops supplying power to the load due to failure or maintenance, the DG fails to detect the power outage ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38G01R31/00
CPCH02J3/388G01R31/00H02J2300/26Y02E10/56H02S50/00G05F1/67H02J1/12H02J1/106Y02P80/14H02S40/30H02J13/00002H02J1/10H02S10/00
Inventor 陈晓龙杨志颖李斌李永丽李博通
Owner TIANJIN UNIV
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