Three-phase short-circuit current calculation method of photovoltaic power generation system considering phase-locked loop transient response
Photovoltaic power generation system has different fault response characteristics from synchronous ma-chine,which brings severe challenges to power grid fault protection and control.The output of the phase-locked loop of the photovoltaic power generation system directly affects the fault response characteristics of the photovoltaic system,especially the non-periodic transient response deviation of the output of the phase-locked loop caused by the voltage phase jump after the grid fault,which has a great impact on the short-circuit current.The existing studies ignore the phase-locked transient process or assume that the phase-locked deviation is constant,which may cause large errors in the analytical calculation of photovoltaic short-circuit current.For this reason,in the present paper the expression of the deviation between the output phase of the photovoltaic phase-locked loop and the voltage phase of the grid-connected point is derived,the time-domain variation characteristics of the phase-locked deviation and its influencing factors are analyzed,and the influence of the phase-locked deviation on the three-phase short-circuit current of the photovoltaic power generation system is analyzed,thus the analytical calculation method of the three-phase short-circuit current of the photovoltaic power generation system considering the transient response of the phase-locked loop is proposed,and the characteristics of the short-circuit current are analyzed,Finally,the simula-tion model of photovoltaic grid-connected system is built to verify the correctness of the theoretical analysis.
photovoltaic power generationshort circuit currentthree-phase short circuitphase-locked loopfault analysis
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