Circulating current loss of photovoltaic inverter

Is a PV inverter a constant power source?

The PV inverter is modelled as a constant power source, however, for fault analysis, the authors assumed the limiting current to be twice the rated current, for the worst-case scenario. The inverter current and voltage are considered in phase for unit power factor operation.

How does circulating current affect the power rating of a parallel inverter?

The circulating current deteriorates the output current quality and degrades the reliability of the parallel system [12, 13, 14, 15]. Harmonic components of circulating current can influence the inverter life cycle, limiting the power rating of the total parallel-connected inverter [16, 17].

Do photovoltaic inverters contribute to short-circuit currents?

To conduct this analysis, an autotransformer-based voltage dip generator is proposed as a means to test the photovoltaic inverters' contribution to short-circuit currents. Laboratory tests are then performed to obtain the short-circuit current contribution of eight single-phase photovoltaic inverters.

What causes circulating current in a parallel inverter?

The circulating current is generated by differences in each inverter, such as hardware parameters and control process. The circulating current deteriorates the output current quality and degrades the reliability of the parallel system [12, 13, 14, 15].

Do small-scale photovoltaic inverters affect a protection system's operating time?

Results indicate that while the massive penetration of small-scale single-phase photovoltaic inverters can alter the protection system's operating time, the impacts are not significant. Only in very specific scenarios, such as events related to high impedance faults, some impact can be observed.

How to reduce circulating current in a modular inverter?

The reduction methods for modular inverters are compared in terms of efficiency, performance, and reliability. The possible approaches for circulating current reduction are categorized into three groups–hardware, control, and modulation. Each reduction method is discussed according to the category.