Anti-islanding protection test circuit and method based on constant impedance load simulation

Abstract

The invention aims to provide an anti-islanding protection testing circuit based on constant impedance load simulation; the circuit comprises a constant impedance load simulation unit, a monitoring unit and a measuring unit; the input end of the measuring unit is connected with the output end of a grid-connected photovoltaic inverter; the first output end of the measuring unit is connected with a 0.4kV power distribution network; a bypass switch is connected between the input end of the constant impedance load simulation unit and the first output end in parallel; the first input end of the monitoring unit is connected with the second output end of the measuring unit; the second input end of the monitoring unit is connected with the output end of the constant impedance load simulation unit; the third input end of the monitoring unit is connected with the second output end of the bypass switch. The constant impedance load simulation unit accurately simulates load characteristics of a parallel RLC (radio link control) load and feeds an active power output by the grid-connected photovoltaic inverter to the power distribution network in a unit power factor, so that the anti-islanding protection of the grid-connected photovoltaic inverter is enabled to be triggered in testing process; the circuit and the method disclosed by the invention have the advantages of no obvious heating, compact device and the like.

Description

technical field [0001] The invention relates to a test circuit, in particular to an anti-islanding protection test circuit based on constant impedance load simulation. Background technique [0002] With the large number of distributed photovoltaic power sources connected to the distribution network, the possibility of unplanned islands also increases. If an unplanned island occurs, the "reverse power transmission" of distributed photovoltaic power generation will seriously threaten the safety of power operation and maintenance personnel. The distributed photovoltaic power supply is connected to the grid through the inverter interface. In order to prevent unplanned islanding, the grid-connected photovoltaic inverter must be equipped with an anti-islanding protection function. At present, the scheme based on adjustable RLC load is widely used to test and verify the anti-islanding protection function of grid-connected photovoltaic inverters. The device is too large, requires a...

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Problems solved by technology

[0004] In order to solve the problem of testing and verifying the anti-islanding protection function of grid-connected photovoltaic inverters based on the scheme based on adjustable RLC load, the present invention has the problem that the appearance of the device is too large, a high-power fan is required for heat dissipation, and feedback energy saving and long-term operation adjustment cannot be realized. Aiming at the problem of decreased accuracy and the difficulty of carrying out the anti-islanding protection test of grid-connected photovoltaic inverters at the site where distributed photovoltaic power generation is connected, an anti-islanding protection test circuit based on constant impedance load simulation is proposed

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