In photovoltaic systems, parasitic capacitance is often formed between PV panels and the ground. Because of the switching nature of PV converters, a high-frequency voltage is usually generated over these parasitic capacitances; this, in turn, can result in a common-mode current known as leakage current.
There are two distinct methods to eliminate the leakage current in the solar PV array system: (i) obstruct the leakage current, (ii) reduce the variation/constant common-mode voltage. The additional diodes/switches are incorporated in the system to obstruct the leakage current by disconnecting the PV array from the grid side network.
How to reduce leakage currents in single-phase PV connections?
According to the above analysis, there are mainly three directions that can be adopted to eliminate or minimize leakage currents in single-phase PV connections: Using of common-mode (CM) chokes: this represents an effective solution to mitigate the leakage current in grid-connected systems .
How effective is PV leakage strategy?
The comparative analysis with the state-of-the-art techniques shows the effectiveness of the strategy. Under all test conditions, the harmonics in grid currents are observed within limits as per the IEEE-519 and IEC-61727 standards, whereas the PV leakage currents are maintained well within the range recommended by VDE-00126 standard.
The solar PV array current is not varied, which evinces that maximum power generation is not varied. The grid currents are well-balanced and sinusoidal, which illustrates that the negative sequence power is not injected from the SECS. Fig. 14d shows the waveforms of VCM, ILeak, isa, iLaa.
Nowadays, the solar photovoltaic (PV) array system has become popular in renewable power generation due to the advantages such as ease of installation, low maintenance cost etc. The typical topologies for the solar energy conversion system (SECS) are reported in [1, 2] to meet the power demand of the load side network.
How does parasitic capacitance affect a photovoltaic system?
In photovoltaic systems, parasitic capacitance is often formed between PV panels and the ground. Because of the switching nature of PV converters, a high-frequency voltage is usually generated over these parasitic capacitances; this, in turn, can result in a common-mode current known as leakage current.