Electronic converter for the analysis of photovoltaic arrays and inverters

This paper proposes a bidirectional electronic converter that both measures the characteristic curves of photovoltaic generators and physically emulates their real-time physical behaviour. The two converter operation modes (emulation and measurement) are digitally implemented in a microcontroller. The converter current is controlled by means of an analogical variable-hysteresis control loop, whose reference is provided by the microcontroller. In the measuring operation mode, a digital voltage control loop is implemented to make the photovoltaic generators cover their I-V characteristic curves. In the emulating operation mode, the voltage is measured and the current reference is calculated from the programmed or measured I-V characteristic curve. The system can measure three times per second the characteristic curves of up to seven photovoltaic generators and then emulate their electrical behaviour to test photovoltaic inverters. Analysis of photovoltaic generators and inverters can thus be reliably carried out, and the results can help to both compare their performance and achieve optimal configurations. Simulation and experimental results are very satisfactory.