Photovoltaic island protection method and system based on communication network

Abstract

The invention provides a photovoltaic islanding protection method and system based on a communication network. The photovoltaic islanding protection method comprises the steps that an anti-islanding microcomputer device carries out islanding detection for the first time; judging whether the result of the first island detection meets a first island characteristic standard or not; the anti-islanding microcomputer device issues an instruction to enable the inverter to generate disturbance quantity in the power grid; the anti-islanding microcomputer device performs islanding detection for the second time; and judging whether the result of the second island detection accords with a second island characteristic standard, if the photovoltaic power generation system has an island effect, disconnecting the photovoltaic power generation system from the power grid, and controlling the inverter to stop running. According to the invention, the first detection standard is used as the switching basis of active detection, and the second detection standard is used as the final judgment basis of the final island protection action, so that on one hand, the power quality damage caused by the long-time injection of disturbance to the power grid by the photovoltaic power generation system can be avoided; and on the other hand, the island detection speed and accuracy can be ensured.

Description

technical field [0001] The present invention relates to the technical field of power systems, and in particular, to a method and system for protecting photovoltaic islands based on a communication network. Background technique [0002] Island protection is an important part of the relay protection of photovoltaic power plants. It is required that when the islanding effect occurs, the grid connection point can be quickly cut off, so that the photovoltaic power station can be quickly separated from the grid system side, so as to ensure the safety of the entire power station equipment and related maintenance personnel. [0003] The islanding detection methods of photovoltaic power plants can be divided into two categories: active and passive. Passive detection is easy to implement and has no effect on the power quality and stability of the system. Active detection overcomes the shortcomings of passive methods, reduces the blind area of ​​island detection, and speeds up detecti...

AI Technical Summary

Problems solved by technology

However, in the active method, because the disturbance is added to the inverter control signal, the output current waveform of the inverter is distorted, which affects the power supply quality of the photovoltaic power generation system.

[0004] Existing patents have proposed an island detection method combining active and passive methods, which needs to detect the matching degree of load power and photovoltaic power generation. In actual engineering, when the local load is small or does not exist, the photovoltaic power No match, it is not suitable to use the matching degree of load power and photovoltaic power generation as the basis for switching between active and passive methods

In addition, for the direct connection of large-scale photovoltaic power plants to the grid, the load situation is almost impossible to detect

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