An improved synchronous reference frame current control strategy for a photovoltaic grid-connected inverter under unbalanced and nonlinear load conditions

Abstract

In recent years, renewable energy sources have been considered the most encouraging resources for grid and off-grid power generation. This paper presents an improved current control strategy for a three-phase photovoltaic grid-connected inverter (GCI) under unbalanced and nonlinear load conditions. It is challenging to suppress the harmonic content in the output current below a pre-set value in the GCI. It is also difficult to compensate for unbalanced loads even when the grid is under disruption due to total harmonic distortion (THD) and unbalanced loads. The primary advantage and objective of this method is to effectively compensate for the harmonic current content of the grid current and microgrid without the use of any compensation devices, such as active and passive filters. This method leads to a very low THD in both the GCI currents and the current exchanged with the grid. The control approach is designed to control the active and reactive power and harmonic current compensation, and it also corrects the system unbalance. The proposed control method features the synchronous reference frame (SRF) method. Simulation results are presented to demonstrate the effective performance of the proposed method.

A hybrid voltage‐current compensator using a synchronous reference frame technique for grid‐connected microgrid under nonlinear load conditions

“…Figure 7 shows the unit step response of the system as well as a comparison with the compensators proposed in existing literature. 4,12,28,33 The transient period for the proposed compensator achieves steady state in about 0.55 seconds with ±2% band. On the other hand Trinh and Lee, 12 Mousazadeh Mousavi et al, 4 Naderipour F I G U R E 7 Comparison of proposed EVIR regulating method with existing literature et al, 28 and Moussa et al 33 show a sluggish response requiring 2.2, 2.9, 1, and 1.2 seconds, respectively.…”

“…An increase in the excitation current in the field winding of the generator causes the terminal voltage to F I G U R E 5 System configuration increase. 28 The EVIR controls the voltage/current using power electronic devices; they are an actuator, exciter, generator, and sensor. 29 If we denote the rated voltage, rated current, measured voltage, output voltage, and output current of an EVIR system by…”

“…A lower value of THD is considered better. The THD for the proposed compensator and the compensators proposed in existing literature 4,12,28,33 are given in Table 3. We have also included a column for the base case where no compensator is used.…”

En route of electric vehicles with the vehicle to grid technique in distribution networks: Status and technological review

“…In the article the random charging causes substantial current harmonic distortion to the source current. The authors in Reference proposed an improved current control method for a 3 − ϕ PV‐grid‐connected inverter under imbalanced and nonlinear load scenarios. It effectively reduces the harmonic content of the microgrid and power grid without consuming any additional compensation devices.…”

A Harmonic Compensation Strategy in a Grid-Connected Photovoltaic System Using Zero-Sequence Control

“…One of the problems is existence of zero-sequence circulating current flowing between parallel converters. It ought to be specified that in previous studies around three-phase MGs, the zero-sequence component of voltage and current in the grid-connected inverter in microgrids are not taken into account [15][16][17].…”