A multi-machine parallel circuit, power supply system and voltage regulation method

Abstract

The invention discloses a multi-unit parallel circuit, a power supply system and a voltage regulation method. The multi-unit parallel circuit comprises N photovoltaic inverters which are connected in parallel, the output ends of the N photovoltaic inverters are connected with the input ends of an isolation transformer, the input ends of each of the N photovoltaic inverters are connected with at least one cell panel, the cell panels are used for supplying input voltages to the photovoltaic inverter, the output voltages of the cell panels of each photovoltaic inverter are equal, only the cathode of the first photovoltaic inverter among the N photovoltaic inverters is earthed, wherein N is an integer and is greater than or equal to 2; the number of the cell panels connected with the input ends of the first photovoltaic inverter is greater than the number of the cell panels connected with the input ends of any other photovoltaic inverter among the N photovoltaic inverters. By means of the technical scheme, the cathodes of the photovoltaic inverters can be prevented from generating negative voltages to earth, and thereby the technical problem that the inverters of the inverter grid connection circuit in the prior art can leak current to earth is solved.

Description

technical field [0001] The invention relates to the field of optoelectronic technology, in particular to a multi-machine parallel circuit, a power supply system and a voltage regulation method. Background technique [0002] In solar power generation technology, the potential potential induced degradation (Potential Induced Degradation, PID) of photovoltaic modules refers to: when a solar module and the ground form a high-intensity negative voltage, the resulting potential difference will not only cause damage to the solar cell or module, but also cause The problem of attenuation of power generation efficiency affects the power generation capacity and total output power of the entire system. [0003] In the prior art, in order to prevent the PID phenomenon, the negative poles of multiple inverters are grounded, the output terminals of the multiple inverters are connected to the same output isolation transformer, and the output isolation transformer outputs AC power to the gri...

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Problems solved by technology

[0004] However, since the anode voltages of each inverter are inconsistent, and the internal midpoint potentials of each inverter are equal, when the anode voltage of each inverter fluctuates, there will be a large gap between the inverter and the ground wire (Protecting Earth, PE). Large leakage current causes the inverter to lose control of the ground leakage current and cannot work stably

[0005] It can be seen that the inverter grid-connected circuit in the prior art has the technical problem of inverter leakage current to the ground

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