Island protection method based on low-voltage distributed photovoltaic access management and control system

Abstract

The invention provides an islanding protection method based on a low-voltage distributed photovoltaic access management and control system, and the method comprises the steps: taking a voltage frequency swing range delta f and a voltage amplitude swing range delta U within a set time T as the determination of an islanding protection mode, and if the absolute value of the voltage frequency swing range is greater than or equal to 0.2 Hz or the absolute value of the voltage amplitude swing range is greater than or equal to 20V, starting the islanding protection mode; if yes, the passive island detection criterion is established, the low-voltage intelligent circuit breaker judges that the island effect occurs, and the grid-connected point is cut off immediately and reported to the intelligent gateway; if the absolute value of the voltage frequency swing range is smaller than 0.2 Hz, active island detection is started, and disturbance is injected to the output current of the inverter. On the premise of considering electricity utilization safety and electric energy quality, secondary protection for preventing the islanding effect is effectively achieved, and it is ensured that a power grid is safer and more reliable.

Description

technical field [0001] The invention relates to the technical field of distributed power generation, in particular to an island protection method based on a low-voltage distributed photovoltaic access control system. Background technique [0002] In recent years, with the rapid growth of energy demand and the over-exploitation of non-renewable energy, my country's photovoltaic power generation has fully entered the stage of large-scale development. In a grid with distributed photovoltaic grid-connected access, the islanding effect is defined as: when the grid loses voltage, the grid-connected photovoltaic power generation system still maintains the state of continuing to supply power to a certain part of the grid in the lost voltage grid. The islanding effect will not only cause harm to the power grid load or personal safety, but also affect the power quality. The specific manifestation is that the power supply voltage and frequency in the power island area are unstable, whi...

AI Technical Summary

Problems solved by technology

The passive islanding detection method is easy to implement and does not affect the power quality, but when the inverter output power is basically balanced with the local load, the detection blind area is large; the active anti-islanding detection method has a small detection blind area and high sensitivity, but it will have a negative impact on the power quality. influences

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