Abstract
The hysteresis current controller (HCC) for grid following inverter (GFI) system with <inline-formula> <tex-math notation="LaTeX">$LCL$ </tex-math></inline-formula>-filter is a well-known controller for its robustness, fast reference tracking, better dynamics, and easier implementation compared to other controllers. However, HCC behaves differently while integrating such a system with solar photovoltaics (PV). The PV-based GFI system requires fast convergence while transferring maximum power from PV to the grid at minimum converter losses through GFI. This paper therefore proposes a modified double-band HCC (MDBHCC) with proportional resonant (PR) controller for single-phase PV integrated GFI system with LCL-filter. The proposed algorithm implements a unipolar symmetrical PWM strategy for reducing inverter switching losses through a sequential logic with an adaptive clock. It improves the variation in switching frequency and limits the maximum switching frequency of HCC while enhancing the total harmonic distortion (THD) of the injected current into the grid at the point of common coupling. To alleviate the power quality problem and achieve zero steady state error, the proposed MDBHCC with PR control operates at lesser % THD. Simulation and experimental results are presented, with a significant decrease in switching frequency and an improvement in grid current harmonics at both steady-state and dynamic conditions.
Highlights
I MPROVEMENT in power electronics technology creates the way for the renewable energy source (RES) to raise its contribution in distributed power generation (DPG)
Considering ppv as total power transferred to the grid as of Fig. 1, the reference grid current (i∗pv) required to inject at point of common coupling (PCC) can be obtained by current estimation algorithm followed by a unit template signal generated by using the estimated grid phase angle obtained from a state-of-theart SOGI based phase locked loop (PLL) [37]
The performance of the proposed hysteresis current control method with respect to the PV-based single-phase grid following inverter (GFI) system accompanied by LCL-filter is validated by experiment and simulation, and the parameters are provided in table 2
Summary
I MPROVEMENT in power electronics technology creates the way for the renewable energy source (RES) to raise its contribution in distributed power generation (DPG). The power transmitted towards the power grid needs a quality current demand from the photovoltaic (PV) based DPG unit [1], [2]. Due to the random and stochastic character of PV based DPG structure, the regulation of the grid following inverter (GFI) becomes an enacting task in terms of the grid power injection [3]. A fast and effective control algorithm is desirable for stable operation of PV-based GFI with grid regulation
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