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Second-order generalized integrator (SOGI) based phase-locked loops (PLLs) are widely used for grid synchronization in single-phase grid-connected power converters. Previously, the estimated frequency of the PLL stage is fed back to the frontend SOGI block to make SOGI-PLLs frequency-adaptive, which increases the implementation complexity, and make...
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... stability margin, and filtering capability, which has been well discussed in many publications [14] [15]. Here, k p = 137.5 and k i = 7878 are selected for the SOGI-PLL according to [14]. For the comparison purpose, the same control parameters are used in the FFSOGI-PLL. The bode plots of the G ol SOGI (s) and G ol F F SOGI (s) are plotted in Fig. 6. It is clear that the FFSOGI- PLL has nearly the same performance with the SOGI-PLL in the low-frequency range. However, the FFSOGI-PLL provides a higher phase margin, hence, a more stable ...
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Three-phase AC-DC and DC-AC power converters have been extensively employed as grid-interfaces in various applications, e.g., distributed generation and energy storage systems. In these applications, power converters should always synchronize with the main grid so that active and/or reactive power can properly be regulated while maintaining desired...
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... Integrator-based and adaptive filters-based controllers have encountered these challenges. Regarding these researchers have suggested control techniques like mixed second and third-order generalized integrator with frequency locked loop (MSTOGI-FLL) [13], Sign Regressor Least Mean Fourth (SRLMF) [14], Adaptive and Nonadaptive Filter [15], and Improved Linear Sinusoidal Tracer (ILST) [16]. These approaches have found use in specialized power devices for grid-connected converters. ...
... Basically, MAFs [13], NFs [14], and delayed signal cancellation (DSC) [15], are commonly effective in unbalanced and distorted conditions. Second-order generalized integrators (SOGIs) [17], [18] and derivative-based orthogonal signal generators (OSGs) [19] are the most common examples of single-phase OSGs in pre-filtering. Using LPFs and OSGs, in-phase and quadrature-phase signals are delivered to the instantaneous symmetrical component (ISC) to extract fundamental frequency positive sequence (FFPS) from the contaminated three-phase grid voltage. ...
The performance enhancement of an inverter-based grid-connected system necessitates a fast and accurate dynamic response in terms of estimating three-phase grid voltage attributes. The synchronous reference frame phase-locked loop and/or the frequency-locking (i.e., frequency-locked loop) approaches are widely used in practical applications. However, due to the phase/frequency feedback loops, the aforementioned parameter estimation schemes may experience instability and provide a slow dynamic response. This work presents a PLL-less grid synchronization solution for three-phase applications to counter the slower dynamic response and demonstrate better immunity against the non-ideality of a three-phase grid. In order to remove even and odd-order harmonics and extract the fundamental frequency positive sequence (FFPS), the proposed method employs a combination of band pass filters (CBPF). Additionally, a novel frequency estimation algorithm is developed, which accurately estimates the angular three-phase grid frequency. Furthermore, the phase angle and amplitude are adaptively estimated using an off-line error-resolving approach, which is derived from the transfer function of the proposed pre-filtering solution. Finally, the experimental findings validate the robustness of the current proposal.
... The grid integration of a solar PV system employing a cascaded H-bridge multilevel inverter using a damped second order generalised integral (SOGI) is demonstrated to be superior [19]. A fixed frequency SOGI control [20] phase locked loop is demonstrated. The system frequency may deviate during disturbances and hence a frequency adaptive SOGI gives better performance. ...
... The AC grid synchronisation algorithm presented in [20] is improved with a frequency adaptive second order generalised integral control instead of a fixed frequency one. The control algorithm used to operate the grid connected VSC is shown in Fig. 6(c). ...
Due to safety considerations and the challenges involved in tracking the maximum output of series-connected cells, solar photovoltaic (PV) arrays are generally operated at lower voltage levels. A multiport converter can be used to interface telecom DC loads, typically rated at 48 V and powered by PV arrays and battery energy storage systems. The grid integration of the system improves reliability while lowering the BESS rating. This work proposes a sliding mode control-based power flow management controller that maintains the load voltage of a telecom DC load, allows maximum power extraction from the PV module, and facilitates power sharing with AC grid. A voltage source converter and a high-gain bidirectional converter exchange power with the AC grid. A second-order generalized integral algorithm-based voltage source converter control is provided to inject/absorb active power, reactive power, and eliminate the harmonics of the telecom AC load. Detailed simulation studies employing MATLAB software are performed to validate the functionality of the converter as well as the power flow management control. Moreover, the system’s performance is evaluated using a laboratory-developed experimental prototype.
... To design a single-phase inverter controller in αβ or dq axes, it is necessary to generate a virtual signal, which is quadrature to the original single-phase signal. Researchers have proposed different approaches of QSGbased PLL methods, such as Enhanced PLL [9], SOGI-based PLL [10], T/4 delay PLL [11], and inverse Park transform PLL [12]. ...
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... Having this in mind, this paper presents an auto-tuning algorithm for PID-type controller that implements straightforward and low computational load techniques for the estimation of the basic set of parameters for PID controller design. A combined approach to the estimation of limit-cycle resonance frequency and amplitude is proposed, which uses an extended Kalman filter (EKF) [30,31] as the estimator of free oscillator model resonance frequency, cascaded to a second-order generalized integrator (SOGI) filter [32] used as the estimator of the limit-cycle oscillations amplitude, with both estimators having a relatively low complexity and computational load. Based on the estimated limit-cycle oscillation parameters, Takahashi modifications of Ziegler-Nichols rules [33] are used for subsequent tuning of discrete-time PI and PID controllers. ...
... Figure 5a shows the overall block diagram representation of the above scalar (first-order) EKF estimator of the limit cycle resonance frequency , whereas Fig. 5b shows the principal representation of the limit cycle amplitude estimator. In the latter case the high-pass filtered error signal eF is forwarded to so-called second-order generalized estimator (SOGI) [32], which is capable of reconstructing both the direct (in-phase) error component ed and its orthogonal counterpart eq (delayed in phase by /2) in the vicinity of its band-pass frequency ̂ (provided by the EKF estimator). Using the aforementioned direct and quadrature signals, the estimated amplitude ̂1 of the error signal can be obtained as follows: ...
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... Having the above discussion in mind, this paper proposes an automatic tuning algorithm based on a suitable control-oriented process model of the torsional oscillator and utilization of a modified-mixer phase detector phase locked-loop (MMPD-PLL) system (Thacker et al. 2011) equipped with adaptive second-order generalized integrator (SOGI) filter (Xiao et al. 2017) for drive resonance mode key feature extraction. This contribution shows that a single-stage closed-loop experiment with the default-tuned proportional-integral (PI) speed controller can obtain sufficient information about the key drill-string parameters to accurately tune the external active damping system based on torsional torque feedback (Pavković et al. 2019a) for different characteristic drillstring configurations, which is able to suppress the drill-string torsional vibrations normally occurring during drilling operations. ...
... The auto-tuning algorithm in Fig. 5 receives the motor torque reference m R that is high-pass filtered first to remove any offset that may be present due to motor-side friction losses (Coulomb friction) in the gearbox and motor bearings which the top-drive Principal block diagram representation of the automatic tuning system based on MMPD-PLL resonance frequency estimator and adaptive SOGI band-pass filter motor speed control loop needs to account for. The high-pass filtered torque signal m RF is then forwarded to the adaptive band-pass filter implemented as a second-order generalized integrator (SOGI), see Xiao et al. (2017). SOGI extracts the main harmonic component in the vicinity of its central frequency c and is also capable of reconstructing both the direct (in-phase) torque reference component m Rd and its orthogonal counterpart m Rq (delayed in phase by π /2 with respect to the direct component). ...
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... A frequency-variable SOGI-PLL was presented first in [25] and analyzed in detail in [27]. The "Frequency-fixed SOGI-PLL" (FFSOGI-PLL) approach was introduced in [28] while the "Derivative Elements-PLL" (DE-PLL) was presented in [35]. These single-phase PLLs (SOGI-PLL, FFSOGI-PLL and DE-PLL) were compared and discussed in [29]. ...
... If a frequency drift occurs with unbalances, different PSC amplitudes and, as a consequence, second order ripple would appear in the SRF. To handle this problem, an amplitude adjustment equal to [28] will be suggested by multiplying the quadrature signals withω/ω 0 . ...
... From (14b) it can be seen that θ FF −θ ϵ will be summed up with D q (t). With respect to the ANS, the q-axis can be expressed in the Laplace domain as [28] V q (s)=(θ FF (s) − θ ϵ (s)) + D ′ q (s) ...
This paper offers a detailed analysis as well as a tuning and discretization approach of the presented frequency-fixed dual second order generalized integrator based phase-locked loop (FFDSOGI-PLL) for three-phase power systems. The method combines different single- and three-phase PLL approaches by ensuring high phase- and frequency tracking properties. The comparison with the standard frequency-variable DSOGI-PLL and three different recently published three-phase frequency and phase-angle estimation systems shows, that this approach gives a fast and stable phase and frequency detection of the grid voltage with very low computational burden. The results are applicable to, for instance, photovoltaic or frequency converters or active power filters.
... Hence, many advanced PLLs take the SRF-PLL as their fundamental part and add new blocks into SRF-PLL to obtain more accurate phase and frequency estimations. By adding the second-order generalized integrators (SOGIs) into SRF-PLL, the second-order generalized integrator PLL (SOGI-PLL) suppresses high-frequency harmonics in power grids [12][13][14]. Furthermore, modified SOGI-PLLs, such as adaptive frequency-fixed SOGI [15], multiple SOGI [16], and so on are proposed to address the DC and/or unknown frequency harmonics in power grids. ...
In this paper, an integral‐type half‐tangent phase‐locked loop (IHTan‐PLL) is proposed for the varying‐frequency AC grids of more electric aircraft (MEA). First, the performance of the synchronous reference frame phase‐locked loop (SRF‐PLL) and half‐tangent phase‐locked loop (HTan‐PLL) is discussed from a large‐signal viewpoint. When the frequency changes largely, the SRF‐PLL has many oscillations and endures a rather long transient process. The HTan‐PLL can address the large frequency jumps. However, for the varying‐frequency AC grids with harmonic disturbances, the HTan‐PLL still has oscillations in estimating the frequency when the frequency jumps largely. To enhance the performance of the SRF‐PLL and HTan‐PLL, the IHTan‐PLL is developed for the varying‐frequency AC grids with harmonic disturbances. The IHTan‐PLL performs better than the SRF‐PLL and HTan‐PLL in addressing the large frequency jumps. Specifically, under any large frequency changes, the IHTan‐PLL still converges to the equilibrium point (0,0), and no oscillations emerge. In addition, the IHTan‐PLL has better steady‐state accuracy in estimating the frequency than the SRF‐PLL and HTan‐PLL. The experimental results also demonstrate the superior performance of the proposed IHTan‐PLL.
... DSOGI is often used in three-phase PLL loops [126], [127] and frequency-locked loops (FLL) [128], [129], [130] due to its superior performance in the phase and frequency estimation [131], [132], [133]. Additionally, from source currents and/or voltages, it precisely extracts positivenegative sequence harmonic components [115], [116]. ...
... Parameters of power converters and controllers are given in the Table I below. Also, there should be a minimum ratio t sFLL ≥ 2t sSOGI based on the empirical approach [126], [129]. ...
In recent years, integrating renewable energy sources (RESs) has achieved significant attention due to the growing demand for sustainable energy solutions. Inverter-interfaced Islanded Microgrids (IGs) have appeared as an advantageous approach to integrating RESs into the power grid. Grid-forming inverters (GFIs) are a critical component of IGs, and their synchronization is essential for stable and reliable operation. The literature has widely proposed soft transition, pre-synchronization, and re-synchronization to synchronize IGs to the main grid. However, methods for synchronizing GFIs in the islanded microgrid are restricted. Parallel operation of GFIs is required to guarantee the high power demand of IG and improve voltage-frequency stability. For parallel operation, GFIs must be synchronized with each other. In the conventional synchronization control systems that are highly nonlinear, the linear proportional-integral (PI) controllers are commonly used in synchronization loops without considering the nonlinearity resulting from the initial condition dependency and cross-coupling. Thus, conventional synchronization methods can be exposed to concerns of stable operation, narrow operation area, and performance degradation. This study proposes a new linearized synchronization control system for GFIs in IGs. In this way, it is possible to analytically design robust linear controllers and ensure a stable operation, high performance, and wide (full) operation area. In addition, a new soft-commissioning method is proposed to deactivate synchronization loops and soft-start the synced GFI. The proposed system has been tested in real-time and CHIL hardware setups for two 550 kW GFIs operating in parallel, and the results in the perfect agreement are presented in this study.
... To achieve DPLL in MCR-WPT systems, it is necessary to detect the phase relationship between the current and voltage of the primary coil in the system. The traditional phase difference detection method uses a comparison circuit to convert the current signal into a pulse width modulation (PWM) wave and inputs it together with the original voltage signal into the capture units of the programmable chips to obtain the phase difference between the current and voltage [18][19][20]. This approach is simple, but the capture units of the programmable chips have inherent sampling errors that cannot be overcome, making it difficult to meet high-precision requirements. ...
