Potential-induced degradation prevention circuit and photovoltaic system using same

Abstract

The invention relates to a potential induced degradation prevention circuit and a photovoltaic system using the same. The potential-induced degradation prevention circuit comprises a rectifier and a DC / DC converter. The input end of the rectifier is connected with the output end of the inverter, and the rectifier is provided with a positive output port, a negative output port and a voltage midpoint port. And the input end of the DC / DC converter is connected with the positive output port and the negative output port of the rectifier, and the output end of the DC / DC converter is connected to the voltage midpoint port of the rectifier and the ground respectively, and is used for raising the PV-to-ground voltage of the photovoltaic module when the inverter works so as to enable the PV-to-ground voltage to be greater than or equal to 0V. The photovoltaic system comprises a photovoltaic module, an inverter, an isolation transformer and the potential induced degradation prevention circuit. The circuit is simple in structure and reliable in performance, the PID effect of the photovoltaic module can be effectively prevented, meanwhile, the site construction complexity of a power station is reduced, the manual input of the system is reduced, and the operation and maintenance cost is reduced.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic power generation, and in particular relates to a potential-induced attenuation prevention circuit and a photovoltaic system using the circuit. Background technique [0002] Photovoltaic grid-connected inverter technology is currently relatively mature. From the number of grid phases, it can be divided into three-phase grid-connected inverters and single-phase grid-connected inverters. From the perspective of grid-connected isolation type, it can be divided into isolation type and non-isolated grid-connected inverters. In the field of photovoltaic ground power stations, almost all photovoltaic systems use inverter systems with box-type transformers to realize photovoltaic modules feeding DC power to high-voltage grids. The three-phase grid-connected inverter almost adopts the scheme of boosting the voltage to the DC bus, and the DC bus passes through a three-level or multi-level inverter topo...

AI Technical Summary

Problems solved by technology

Existing PID prevention schemes need to use resistors or capacitors to construct a three-phase neutral line device inside the converter. The construction of the resistance scheme will bring losses, and at the same time, the application of neutral line device capacitors and resistors will increase the cost. At the same time This solution requires the voltage compensation device to be placed inside the converter, which will undoubtedly increase the cost of the system for a system with multiple inverters

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