Abstract:

Driven by the dual carbon goals,the grid-connected scale of distributed photovoltaic (PV) expands rapidly.The randomness and intermittency of its output are prone to causing power quality issues.Traditional reactive power compensation devices misjudge easily in bidirectional power flow,because the superposition of inverter active current and load current changes the phase characteristics,resulting in under-compensation or over-compensation.To slove this problem four progressive solutions are proposed:topology reconstruction at the point of common coupling (PCC),upgrading of refined reactive power compensation equipment,deployment of four-quadrant reactive power compensators,and intelligent software control for dynamic reactive power regulation of inverters.A simulation model of a 2 MW PV power station is built via MATLAB/Simulink,which verifies that the software dynamic regulation strategy can restore the power factor from 0.86 to above 0.91 within 3 seconds,with a steady-state error less than 0.01.The feasibility of this method is also verified by practical engineering cases.A theoretical basis and technical path are provided for power quality optimization of distributed PV projects.

Key words: distributed photovoltaic, power factor, reactive power compensation, grid-connected inverter, power quality