One of the problems with the doubly-fed induction generator (DFIG) is its high vulnerability to network perturbations, notably voltage dips, because of its stator windings being coupled directly to the network. As the DFIG’s stator and rotor are electromagnetically mated, the stator current peak occurs during a voltage dip causing an inrush current to the critical converter back-to-back and an overload of the DC-link capacitor. For this purpose, a series of researchers have achieved a linear and non-linear controller with a crowbar-based protection scheme. With this type of protection, the Rotor Side Converter (RSC) is disconnected momentarily, and consequently, its control of both the active and reactive output power of the stator is totally lost, leading to incorrect power quality at the point of common coupling (PCC). In this document, a robust nonlinear controller by Advanced Backstepping with Integral Action Control (ABIAC) is initially employed to monitor the rotor and the network side converters under normal network operations. In the presence of a network fault, an improved protection scheme (IPS) is tacked on to the robust nonlinear control to help enforce the behavior of the DFIG system to be able to overcome the fault. The IPS, which is formed by a crowbar and an RL series circuit, is typically located in the space between the rotor coils and the RSC converter. Compared to a standard crowbar, the developed scheme is successful to limit the rotor transient current and DC-link voltage, also an RSC disengagement to rotor windings can be prevented during the fault. Furthermore, the controllers of both the RSC and the Network Side Converter (NSC) are modified to boost the supply voltage at the PCC. A comparative study is also performed between the IPS without and with modification of the reactive power control loops. The simulation results mean that with the modified controllers during the fault, the amount of reactive power sustainment with ABIAC at the PCC is optimized to 17.5 MVAr instead of 15 MVAr with proportional-integral control (PIC). Therefore, the voltage at the PCC is fort increased in order to comply with the voltage requirements of the farm and absolutely to maintain the connection to the network in case of voltage dip.

The doubly fed induction generator (DFIG) is vulnerable to grid faults due to its direct stator connection, causing issues like excess stator current during voltage dips. Consequently, sensitive inverters suffer from increased currents, and the DC-link capacitor undergoes overcharging. This document examines two protection strategies employing a proportional–integral (PI) controller to manage the transient rotor current and mitigate DC-link overcharging, thereby optimizing DFIG behavior during network faults. One option combines a classic crowbar circuit with a DC-chopper, while the other is a modified protection scheme (MPS) that includes an impedance with passive elements and a crowbar. The impedance forms a resistance R_p parallel with an inductance L_p. Both configurations, situated between the rotor coils and the rotor-side converter (RSC), augment the capacity for low-voltage ride-through (LVRT). MATLAB/SIMULINK simulations of the two schemes demonstrate successful rotor current reduction at 2.9 kA and 3.4 kA, and DC-link tension reduction below and at 1.4 KV. In addition, the conventional crowbar and MPS configurations efficiently restrict the RSC current to levels below 0.21 kA and 2.94 kA, while absorbing up to 2.52 kA and 1.52 kA, respectively. The key difference lies in the fact that fine-tuning the parameters in the MPS design prevents rotor disconnection when faced with a balanced fault. This enhancement enhances machine performance and enables full stator power control via the RSC.

In the wind power area, Doubly Fed Induction Generator (DFIG) has many advantages due to its ability to provide power to voltage and constant frequency during rotor speed changes, which provides better wind capture as compared to fixed speed wind turbines (WTs). The high sensitivity of the DFIG towards electrical faults brings up many challenges in terms of compliance with requirements imposed by the operators of electrical networks. Indeed, in case of a fault in the network, wind power stations are switched off automatically to avoid damage in wind turbines, but now the network connection requirements impose stricter regulations on wind farms in particular in terms of Low Voltage Ride through (LVRT), and network support capabilities. In order to comply with these codes, it is crucial for wind turbines to redesign advanced control, for which wind turbines must, when detecting an abnormal voltage, stay connected to provide reactive power ensuring a safe and reliable operation of the network during and after the fault. The objective of this work is to offer solutions that enable wind turbines remain connected generators, after such a significant voltage drop. We managed to make an improvement of classical control, whose effectiveness has been verified for low voltage dips. For voltage descents, we proposed protection devices as the Stator Damping Resistance (SDR) and the CROWBAR. Finally, we developed a strategy of combining the solutions, and depending on the depth of the sag, the choice of the optimal solution is performed.

One significant disadvantage of the doubly fed induction generator (DFIG) is its high vulnerability to grid faults, which can be attributed to the direct linkage of its stator windings to the electrical network. The electromagnetic pairing of the stator and rotor in the DFIG implies that a voltage dip causing excessive stator current results in high currents in the sensitive back-to-back inverters and an overcharge in the DC-link capacitor. A comparative study of two protection configurations with a sliding mode non-linear control (SMC) for the rotor transient current for the better operation of the DFIG under network faults is presented in this document. One conventional configuration consists of a crowbar with DC-chopper and another is changed by adding to the crowbar an RL series device known as an appropriate protection configuration (APC). Both are placed within the rotor windings and ride-side converter (RSC) to achieve secures and maintains SMC of DFIG. The comparison of the results reached with the MATLAB/ SIMULINK application is evidenced by the success of these two configuration reduce the high rotor current and DC-link voltage. Additionally, the conventional configuration, in conjunction with the APC, diminishes the current RSC to levels below 0.2kA and exactly 2.25kA, while also being capable of absorbing up to 2.52kA and 1.3kA in the event of a grid fault. So the main difference is that with the APC, the decoupling of the RSC to the rotor in the presence of a fault can be averted, thereby assuring the control of all stator power via the RSC converte.

Partial shading, from obstacles such as buildings or trees, is a major challenge for photovoltaic systems, causing unpredictable fluctuations in solar energy production and underlining the need for advanced energy management strategies. In this paper, we propose an innovative approach that combines hybrid metaheuristic optimization with maximum power point tracking control (MPPT), using particle swarm optimization (PSO) in conjunction with the incremental conductance (IC) algorithm. We compare the proposed method with the conventional Perturb and Observation (P&O) algorithm. The choice of P&O as a comparison method is due to its simplicity, its familiarity with the scientific literature, its low cost of implementation. The main objective of swarm optimization combined with the IC algorithm lies in its ability to overcome the challenges posed by partial shading, ensuring accurate and efficient tracking of the point of maximum power, thanks to dynamic adaptation to variations in solar irradiation, thus enhancing the performance and resilience of the photovoltaic system. This approach is of crucial importance, offering considerable potential for solving the complex challenges associated with partial shading. Our results show that this hybrid MPPT algorithm offers superior tracking efficiency > 98% , faster convergence 500ms , better stability and increased robustness compared to traditional MPPT approaches. The system is composed of a PV and a boost converter that connects the input to the resistive load. The algorithms were implemented with MATLAB/Simulink as the simulation tool. These results not only reinforce the viability of sustainable energy solutions, but also open the way for the development of more sustainable energy solutions.The perspectives of this work are oriented towards a practical and extended integration of the proposed hybrid approach in real photovoltaic systems, with a particular emphasis on experimental validation.