Abstract
The lack of control in voltage overshoot, transient response, and steady state error are major issues that are frequently encountered in a grid-connected photovoltaic (PV) system, resulting in poor power quality performance and damages to the overall power system. This paper presents the performance of a control strategy for an inverter in a three-phase grid-connected PV system. The system consists of a PV panel, a boost converter, a DC link, an inverter, and a resistor-inductor (RL) filter and is connected to the utility grid through a voltage source inverter. The main objective of the proposed strategy is to improve the power quality performance of the three-phase grid-connected inverter system by optimising the proportional-integral (PI) controller. Such a strategy aims to reduce the DC link input voltage fluctuation, decrease the harmonics, and stabilise the output current, voltage, frequency, and power flow. The particle swarm optimisation (PSO) technique was implemented to tune the PI controller parameters by minimising the error of the voltage regulator and current controller schemes in the inverter system. The system model and control strategies were implemented using MATLAB/Simulink environment (Version 2020A) Simscape-Power system toolbox. Results show that the proposed strategy outperformed other reported research works with total harmonic distortion (THD) at a grid voltage and current of 0.29% and 2.72%, respectively, and a transient response time of 0.1853s. Compared to conventional systems, the PI controller with PSO-based optimization provides less voltage overshoot by 11.1% while reducing the time to reach equilibrium state by 32.6%. The consideration of additional input parameters and the optimization of input parameters were identified to be the two main factors that contribute to the significant improvements in power quality control. Therefore, the proposed strategy effectively enhances the power quality of the utility grid, and such an enhancement contributes to the efficient and smooth integration of the PV system.
Highlights
Global warming, climate change, and alarming levels of air pollution are major concerns that affect human health and natural wealth
A constant direct current (DC) link voltage should be maintained between the boost converter and the inverter device, because any fluctuation across the DC link will cause total harmonic distortion (THD), which leads to poor power quality in the grid system [31]
A 100 KW grid-connected PV power is implemented in the MATLAB/Simulink with constant irradiance and temperature at 1000 W/m2 and 25 ̊C, respectively, to implement the proposed particle swarm optimisation (PSO) for tuning the PI controller parameters in an inverter control scheme
Summary
Climate change, and alarming levels of air pollution are major concerns that affect human health and natural wealth. In view of the above discussion, the references mentioned above have limitations in terms of insufficient process information, less robustness, longer computation time than PSO, facing parameter complexities and coding difficulties to find the best fitness value They did not sufficiently discuss the effects of inverter optimization to improve the power quality performance, reduce the DC link voltage fluctuation, stabilise the output current and voltage, smooth the power flow, decrease the harmonics, and stabilise the frequency in the grid-connected PV inverter. The contribution and key highlights of the paper are as follows: i It proposes an optimized controller-based PSO algorithm to obtain the optimum values of Kp and Ki in real-time operation to improve the power quality and stability of the threephase grid-connected PV inverter system. It offers a real-time operation of the PV inverter system with optimized controller by minimizing the error as much as possible, finding the best optimum parameters of PI controllers under load variation condition
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