Fast Photovoltaic Emulator Based on PV-cell Equivalent Circuit Model

Photovoltaic (PV) emulator is a specific type of power electronic device used to simulate and produce the nonlinear characteristic curves for actual solar panel or array. It usually requires fast computing and power converters with a wide output range. However, the emulator response time is restricted by the controller bandwidth, and it must stabilize the converter for many different operating points. Hence pure power converter based solutions generally have a slower response time when compared with the real PV system. This paper presents a PV emulator based on a PV cell equivalent circuit model. It consists of a constant current source converter (CCSC) and a string of diodes to mimic the nonlinearity of any PV source. The CCSC simplifies the converter and controller designs as it operates at a fixed point for each insolation level, as compared with a converter-based solution which requires a voltage-source converter with wide output operating ranges. This study focuses on two aspects of the PV emulator design. Firstly, a detailed parametric design from model equations to the extraction of practical real PV parameters is explained to estimate the electrical performance of the PV simulator. Secondly, the CCSC and controller designs are explained. An experimental prototype is designed to validate the PV simulator. In addition to steady-state operation, the dynamic response of series connected cells is also emulated to verify the effectiveness of the proposed platform. Both simulations and experimental results are conducted. The response time of the proposed emulator system is comparable to both a benchmarked commercial product and a real PV system.