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

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.