Simple and Fast Dynamic Photovoltaic Emulator based on a Physical Equivalent PV‐cell Model

Photovoltaic emulators are a specific type of power electronics system to mimic the behaviour of a photovoltaic (PV) panel or array and facilitate the testing of energy systems. Existing solutions usually require sophisticated hardware design and fast computing. This paper presents a simple, reliable, and effective circuit-based photovoltaic (PV) emulator based on the equivalent PV stacked cells. The PV emulator can be used for solar system testing and analysis, such as maximum power point tracking (MPPT) and partial shading effect. The – and – characteristic curves of the emulator have been generated by using an LTspice simulator. It is experimentally investigated and compared with a real PV panel and existing emulator products. The experiment results show good agreement with the mimicked actual PV panel. The proposed PV emulator shows a better dynamic response and shorter settling time than several benchmarked commercial products. The enhancement in the time response is due to the simplicity of the emulator, where a few power diodes and some resisters are used. In addition to simplicity, the PV emulator is very cost-effective

Efficiency Improvement Scheme for PV Emulator Based on a Physical Equivalent PV-Cell Model

Recently, a photovoltaic (PV) emulator is proposed which is based on a combination of a constant current source and a one-diode photovoltaic model. Its superior dynamic performance is compatible with that of a real PV system. Although it is power efficient at the maximum power point (MPP), it suffers from high power loss around and at the open-circuit voltage (OCV) operation condition. The PV emulator can be used for PV system analysis and testing, such as maximum power point tracking (MPPT). This paper presents a new switching circuit which is placed in parallel with the diode string to minimize the power loss. The switching circuit consists of a two-switch non-inverting buck-boost DC/DC converter. When the operating point of the PV emulator moves from the current source region to the voltage source region, the converter, which is more efficient, switches in to replace the diode string seamlessly to maintain the circuit operation of the emulator. Experimental results show that in the worst case scenario, i.e. OCV condition, the efficiency and temperature of the proposed solution reach 81.47% and 30.1 °C respectively, as compared with 2.8% and 94.2 °C respectively for the diode string only case. In terms of dynamic response, the proposed PV emulator lags the real PV panel by only 3.5 ms as compared with 120 ms by a commercial emulator under the 30% to 60% insolation change test

A Reconfigurable Three-Port DC-DC Converter for Integrated PV-Battery System

In this article, a new nonisolated three-port dc-dc converter to integrate a battery storage with a photovoltaic (PV) module is proposed for off-grid solar-power applications. The proposed converter can be used to integrate the PV module with a backup battery to minimize the impacts of renewable-energy intermittency and unpredictable load demand. The proposed converter is reconfigurable and able to operate as a conventional boost converter, a buck-boost converter, or a forward converter in different modes to support several power flow combinations and achieve power conditioning and regulation among the PV module, battery, and output port, simultaneously. Nevertheless, the power stage only consists of two switches, one coupled inductor, one diode, and two capacitors. A high-voltage conversion ratio is achieved by using a coupled inductor and by combining the PV module and the battery in series. Experimental results of the proposed converter operating in the steady state and during transitions between different modes are reported

Performance investigation of a PV emulator using current source and diode string

© 2018 IEEE. Energy emulator is a specific t ype o f p ower electronic system to mimic the electrical behavior of an energy source and facilitate the testing of energy system. This paper presents a study of a photovoltaic (PV) emulator which is formed by a current source, a diode string and some resistors. It is constructed according to the one-diode photovoltaic model. Unlike the previous study, this paper focuses on using the model equations to design the circuit parameters of the emulator to mimic a selected PV panel and evaluate the circuit performance from both electrical and thermal perspectives. A laboratory experimental setup is built and tested to verify the design. The emulator is power efficient a t t he m aximum p ower p oint. The highest power dissipation of the circuit occurs at the open-circuit voltage operating point

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