Adaptive variable load anti-islanding method for distributed type photovoltaic power supply

Abstract

The invention relates to an adaptive variable load anti-islanding method for a distributed type photovoltaic power supply. In the method, an adaptive anti-islanding device is adopted. The method comprises the following steps: performing initialization; calculating an impedance angle phi, and adaptively adjusting the impedance angle to enable the impedance angle to be separated from an island non-detection zone; detecting the island, and cutting off the island. On the basis of acquiring all parameters of the distributed type photovoltaic power supply, the adaptive variable load anti-islanding method can be used for exquisitely judging whether the distributed type photovoltaic power supply generates the island and quickly enabling an inverter to operate after the island formation is determined so as to precisely cut off the island; the whole method is small in dead zone, high in precision, high in practicability, simple and feasible.

Description

technical field [0001] The invention relates to an adaptive variable load anti-islanding method for distributed photovoltaic power sources, and belongs to the technical field of secondary protection for distributed power generation in power systems. Background technique [0002] As far as the applicant knows, anti-islanding protection is an essential function when the distributed power generation system is connected to the grid. When the power supply of the distribution network trips due to a fault accident or blackout maintenance, if the distributed photovoltaic power grid-connected power generation system (such as: photovoltaic power generation, wind power generation, fuel cell power generation, etc.) at each user end fails to detect the power failure state in time, then It is unable to cut itself off from the mains network in time, and eventually forms a self-sufficient power supply island composed of the distributed photovoltaic power grid-connected power generation syst...

AI Technical Summary

Problems solved by technology

[0004] However, the existing low-voltage anti-islanding devices still have some disadvantages: (1) When the value of the input capacitive load or inductive load is relatively small, the voltage phase may change slightly, and the change value that is too small will cause the inverter to monitor It is difficult for the device to detect this change, and even if it detects this change, it may not act because it does not exceed the inverter voltage phase change threshold, that is, there is a passive detection blind zone

(2) The existing low-voltage anti-islanding device has not realized the communication connection with the main network, and lacks initiative; if automatic access to the resistive load is adopted at regular intervals, although the access to the resistive load changes the load characteristics, it has no effect on normal operation , only when the resistive load is re-introduced after the island is formed, the active power balance will be destroyed, and the inverter will stop working; however, frequent switching of switches will cause hidden dangers of operating overvoltage, and frequent switching operations will also bring time delays, switch aging, etc. question

However, the complexity of this technical solution is relatively high, and it needs to combine multiple algorithms for detection

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