Proportional–Resonant Controller Based on Virtual Impedance for Harmonic Suppression of ESS-UPS System

A proportional–resonant controller based on the output impedance is proposed for a single-phase full-bridge inverter offering harmonic suppression of uninterruptible power supply with an energy storage system. In order to design the voltage transfer function and output impedance independently, the proposed controller properly places a virtual impedance loop within the output voltage controller, and control gains are selected according to the proposed design rules. To secure a high power quality, the virtual impedance is designed to have low output impedance characteristics in all frequency bands. In addition, some practical issues are analyzed and readily compensated such as parametric error and the performance of output voltage tracking respectively. Mathematical and theoretical analyses are presented to validate the proposed controller, and experiments were conducted to verify its performance

A Design and Validation of 400 W PV Emulator Using Simple Equivalent Circuit for PV Power System Test

In this paper, we propose a photovoltaic emulator (PVE) composed of a series of connected power diodes with a single constant current source, rather than a power converter-based PVE. Accordingly, this enables readily verifying the operation because a the simple hardware structure and lack of a complex control algorithm. The proposed PVE can be intuitively implemented using the proposed selection criteria for the power diode and equivalent resistances. Since there is no feedback control based on complex analog/digital controls and sensors, the control response can be very fast. In addition, the proposed PVE can be easily integrated with a PV power system such as a power optimizer, to allow testing in a simple and flexible manner. Spice simulation was performed based on the electrical characteristics provided by the solar panel manufacturer, and this was utilized to validate the applied emulator circuit model, the Norton Equivalent Circuit. During the design process, the simulation helped to manufacture the PVE within error ranges satisfying the desired I–V and P–V curves, as well as the maximum power point (MPP). Partial shading could be easily implemented through use of the multiple series connection of individual PVEs, demonstrating local MPP and global MPP. A 400 W class PVE was built through appropriate power diode selection, with a thermal design to increase the output power. Moreover, its performance and feasibility were verified through intensive experiments. The measured efficiency, transient response time, and maximum transient error of the partial shading tests were 91%, 22 μs, and 5.8%, respectively

A Design and Validation of 400 W PV Emulator Using Simple Equivalent Circuit for PV Power System Test

In this paper, we propose a photovoltaic emulator (PVE) composed of a series of connected power diodes with a single constant current source, rather than a power converter-based PVE. Accordingly, this enables readily verifying the operation because a the simple hardware structure and lack of a complex control algorithm. The proposed PVE can be intuitively implemented using the proposed selection criteria for the power diode and equivalent resistances. Since there is no feedback control based on complex analog/digital controls and sensors, the control response can be very fast. In addition, the proposed PVE can be easily integrated with a PV power system such as a power optimizer, to allow testing in a simple and flexible manner. Spice simulation was performed based on the electrical characteristics provided by the solar panel manufacturer, and this was utilized to validate the applied emulator circuit model, the Norton Equivalent Circuit. During the design process, the simulation helped to manufacture the PVE within error ranges satisfying the desired I–V and P–V curves, as well as the maximum power point (MPP). Partial shading could be easily implemented through use of the multiple series connection of individual PVEs, demonstrating local MPP and global MPP. A 400 W class PVE was built through appropriate power diode selection, with a thermal design to increase the output power. Moreover, its performance and feasibility were verified through intensive experiments. The measured efficiency, transient response time, and maximum transient error of the partial shading tests were 91%, 22 μs, and 5.8%, respectively