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Top1. Introduction
Technology advancement to address the world’s growing demand for clean and affordable energy will require simultaneous advances in materials science and technology in order to meet the performance demands of new power-generating systems (Kumar, 2019; Rahpeyma & Zarei, 2018; Kinnunen et al., 2018; D'Emilia et al., 2018; Guerbouj et al., 2019; Souli-Jbali et al., 2019; Lajmi et al., 2020; Belkeziz & Jarir, 2020). Nowadays, double-fed induction generator (DFIG) wind turbine is rated as the most widely used wind turbine-based pitch adjusting variable speed wind turbines (Seme et al., 2017). Enhancing the quality of power through the use of DFIG's grid side converter (GSC) control system is now necessary from an economic point of view. Modifying the GSC control design of the DFIG wind turbine to be multifunctional is essential in the context of different grid disturbances and variations in wind speed, as illustrated later in this paper.
Due to its noise pollution, problems arise from the location of most DFIG large-scale wind turbines in isolated places. These areas have weak electrical power grids with low fault current ratios, low response / resistance ratio of the transmission line and under voltage conditions (Xi, et al., 2014).
In order to maintain the voltage stability of the power system, the grid must be capable of injecting or absorbing the necessary reactive power during sudden changes to the grid, such as faults, heavy loading, voltage swell / sag, and taking into account the variable wind that causes voltage fluctuations. The bus voltage at the DFIG wind turbine terminal is local, so it is very costly to control the bus voltage at the remote node by using conventional power stations. This is because the reactive power flow in the system is associated with voltage changes, which increase the loss of power in the electrical grid. It is therefore necessary to mount voltage control devices on the transmission or distribution network or to change the GSC control system (Seme et al., 2017). Significant work on the function of the GSC controller of the DFIG wind turbine has been published in the literature on the control strategy of the double-induction generator during the grid voltage swell. Le et al. (2019) concentrated only on measuring the amplitude of the grid voltage swell through the GSC control system comparator using the PWM technique and analyzed the voltage swell case. Zheng et al. (2017) has proposed resonant control of the grid-side converter in the wind power system under voltage distortion and has been depicted only for unbalanced grid voltage and harmonic distortion. Boutoubat et al. (2013) proposed the control of a DFIG-enabled wind energy conversion system for active generation and improvement of power quality. The GSC was designed to act as a shunt active power filter to compensate for reactive power. Duong et al. (2018) focused on a comparative analysis of controllers to enhance the transient stability of DFIG wind turbines during major disturbances. It was concluded that the GSC was proposed to improve transient stability by using the Crowbar under three phase fault conditions. Wei et al. (2011) suggested a low-voltage, high-capacity DFIG control strategy with a grid-side thyristor-controlled voltage regulator. The proposed model used the GSC-based voltage regulator to achieve the low voltage flow of the DFIG wind turbine.
Right observation of the terminal voltage of the DFIG wind turbine versus real time under grid disturbances and variation in wind speed is needed for efficient operation of any system (Zhang et al., 2016). Previously, the GSC was used for only the main function that regulates the DC link voltage and achieves the unity power factor at its terminals.
The contribution in this study is the comparison between the two GSC control systems in the regulation of the terminal voltage of the DFIG wind turbine in the presence of grid disturbances. The GSC is used to be multifunctional without adding any power electronic devices to save economic costs. A detailed mathematical analysis of the two-level GSC of the DFIG wind turbine-based space vector modulation (SVM) is carried out in this work with different control schemes to illustrate additional functions for it. First, the GSC is used as a Static Synchronous Compensator (STATCOM) based AC voltage magnitude regulator to regulate the terminal voltage of the DFIG wind turbine in addition to its main feature. Second, the GSC serves as the SAPF based load calculation theory for the control of the terminal voltage of the DFIG wind turbine as well as its key purpose. Finally, a detailed mathematical model for the DFIG hysteresis current turbine-based side converter rotor (RSC) to extract the maximum power for any wind speed below the rated speed.