scholarly journals A Single-Phase Globally Stable Frequency-Locked Loop Based on the Second-Order Harmonic Oscillator Model

Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 525
Author(s):  
Gerardo Escobar ◽  
Jonathan Carlos Mayo-Maldonado ◽  
Dunstano del Puerto-Flores ◽  
Jesus E. Valdez-Resendiz ◽  
Osvaldo M. Micheloud
Keyword(s):  
Harmonic Oscillator ◽  
Single Phase ◽  
Initial Conditions ◽  
Reference Signal ◽  
Harmonic Distortion ◽  
Angular Frequency ◽  
Second Order ◽  
Synchronous Reference Frame ◽  
Phase Signal ◽  
Stable Frequency

This paper presents a novel frequency-locked-loop (FLL) scheme that provides estimates of the in-phase and square-phase fundamental components of a distorted single-phase reference signal and an estimate of its fundamental angular frequency. The main feature of the proposed scheme is that its design is fully based on the dynamical model of a single-phase signal generator, namely, the second-order harmonic oscillator (SOHO), which adds originality to the scheme. In fact, the proposed scheme owns a particular structure involving a set of orthogonal signals, which can be seen as the fixed-frame representation of three-phase balanced signals. Additionally, a plug-in block is included as a mechanism to mitigate the effect of the harmonic distortion. A proof of global stability for the proposed scheme based on nonlinear argumentation is also included, which contributes to the novelty of the work and ensures convergence disregarding the initial conditions of the to-be-estimated signal components. In addition, explicit conditions are presented for the tuning of control parameters. Experimental results corroborate the performance of the proposed scheme under angular frequency variations, phase jumps, voltage sags and harmonic distortion on the reference signal. For comparison purposes, also the state-of-the-art second-order-generalized-integrator-based FLL and the single-phase synchronous-reference frame phase-locked loop are tested.

scholarly journals Motor side active power filter for induction motor

2020 ◽  
Vol 11 (4) ◽  
pp. 1711
Author(s):  
H.V. Gururaja Rao ◽  
R.C Mala ◽  
Ambika Joshi
Keyword(s):  
Induction Motor ◽  
Reactive Power ◽  
Control Strategies ◽  
Reference Signal ◽  
Harmonic Distortion ◽  
Active Power Filter ◽  
Active Power ◽  
Variable Frequency Drive ◽  
Power Filter ◽  
Synchronous Reference Frame

Power quality is an important aspect in electrical distribution and utilization systems. Variable frequency drive (VFD) controlled induction motors are widely used in industries. The output current of VFD which is nonsinusoidal is given to the induction motor. This paper proposes a motor side active power filter (MSAPF) so as to provide a pure sinusoidal current to the induction motor. An evaluation of two control strategies has been discussed in this paper i.e. Synchronous Reference Frame (SRF) theory and Instantaneous Reactive Power theory (IRPT) in the generation of the reference signal. These techniques are simulated in MATLAB/SIMULINK environment. These simulations demonstrate the reduction in total harmonic distortion (THD) in the motor current with active filter connected to the motor side.

scholarly journals Synchronous Reference Frame Repetitive Control of a Single-Phase Three-Level Dual-Buck Photovoltaic Inverter

Electronics ◽  
2018 ◽  
Vol 7 (10) ◽  
pp. 226 ◽  
Author(s):  
Jung-Yong Lee ◽  
Younghoon Cho
Keyword(s):  
Reference Frame ◽  
Control Strategy ◽  
Single Phase ◽  
Harmonic Distortion ◽  
Current Control ◽  
Output Current ◽  
Pv Inverter ◽  
Synchronous Reference Frame ◽  
Conduction Mode ◽  
Repetitive Controller

This paper proposes a synchronous reference frame (SRF) control strategy for a single-phase, three-level, dual-buck photovoltaic (PV) inverter. The concept of virtual d-q transformation is adapted to the current control of the inverter, and the repetitive controller is implemented in the SRF. With the proposed control strategy, the memory allocation quantity for the repetitive controller is decreased and the capability of the current reference tracking is maximized. Thus, the proposed method significantly reduces the total harmonic distortion (THD) of the output current in both the continuous conduction mode (CCM) and the discontinuous conduction mode (DCM). In addition, the distortion of the output current is mostly composed of odd harmonics. Odd harmonic expressed to the even harmonic in SRF can be calculated using Park’s transformation. Therefore, a repetitive controller can improve dynamics by considering only even harmonic components in SRF rather than including all harmonics. The simulation and the experimental results verify the effectiveness of the proposed control strategy. The proposed method not only reduces the THD of the output current in both the CCM operation and the DCM operation, but also improves the dynamics of the current controller.

scholarly journals Quaternion-valued single-phase model for three-phase power system

2018 ◽  
Vol 69 (2) ◽  
pp. 183-186
Author(s):  
Xiaoming Gou ◽  
Zhiwen Liu ◽  
Wei Liu ◽  
Yougen Xu ◽  
Jiabin Wang
Keyword(s):  
Power Systems ◽  
Single Phase ◽  
Harmonic Distortion ◽  
Minimum Variance ◽  
Music Algorithm ◽  
Three Phase ◽  
Minimum Variance Distortionless Response ◽  
Zero Sequence ◽  
Phase Signal ◽  
The Fourier Transform

Abstract In this work, a quaternion-valued model is proposed in lieu of the Clarke’s α, β transformation to convert three-phase quantities to a hypercomplex single-phase signal. The concatenated signal can be used for harmonic distortion detection in three-phase power systems. In particular, the proposed model maps all the harmonic frequencies into frequencies in the quaternion domain, while the Clarke’s transformation-based methods will fail to detect the zero sequence voltages. Based on the quaternion-valued model, the Fourier transform, the minimum variance distortionless response (MVDR) algorithm and the multiple signal classification (MUSIC) algorithm are presented as examples to detect harmonic distortion. Simulations are provided to demonstrate the potentials of this new modeling method.

Analysis and simulation of a single-phase seven-level inverter controlled by modified sinusoidal PWM technique

2021 ◽  
pp. 2150024
Author(s):  
V. srinath ◽  
Man Mohan Agarwal ◽  
D. K. Chaturvedi
Keyword(s):  
Pulse Width ◽  
Output Voltage ◽  
Single Phase ◽  
Pulse Width Modulation ◽  
Optimization Technique ◽  
Reference Signal ◽  
Harmonic Distortion ◽  
Modulation Index ◽  
Reference Signals ◽  
Sinusoidal Pulse Width Modulation

In this paper, a modified Sinusoidal Pulse width Modulation (MSPWM) technique and a modified single-phase H-bridge seven-level inverter is proposed. The switching pulses for the proposed seven-level inverter are generated using a single triangular carrier waveform, a fully rectified sinusoidal signal, and three stepped reference signals (Uref1, Uref2 and Uref3). Using optimization technique, the magnitude of the stepped reference signal is determined so that the total harmonic distortion (THD) of the output voltage waveform is minimum and the fundamental component, RMS value of the voltage is improved for a given modulation index Ma as compared to the Sinusoidal Pulse width Modulation (SPWM). By the implementation of the new scheme, the seven-level of the inverter output voltage level (+Vdc, +2Vdc/3, +Vdc/3, 0, −Vdc, −2Vdc/3, −Vdc) is obtained for any given modulation index. Similarly, if only two stepped reference signals are used then the inverter will act as a five-level inverter for any modulating index ma. The proposed MSPWM and seven-level inverter are simulated on MATLAB/SIMULINK for R, R-L load and on a single-phase capacitor-start and capacitor-start-run Induction Motor.

scholarly journals Boundedness of solutions and stability of certain second-order difference equation with quadratic term

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Emin Bešo ◽  
Senada Kalabušić ◽  
Naida Mujić ◽  
Esmir Pilav
Keyword(s):  
Difference Equation ◽  
Initial Conditions ◽  
Second Order ◽  
Quadratic Term ◽  
Real Numbers ◽  
Positive Real ◽  
Order Difference ◽  
Second Order Difference Equation ◽  
Order Difference Equation ◽  
Rational Difference Equation

AbstractWe consider the second-order rational difference equation $$ {x_{n+1}=\gamma +\delta \frac{x_{n}}{x^{2}_{n-1}}}, $$xn+1=γ+δxnxn−12, where γ, δ are positive real numbers and the initial conditions $x_{-1}$x−1 and $x_{0}$x0 are positive real numbers. Boundedness along with global attractivity and Neimark–Sacker bifurcation results are established. Furthermore, we give an asymptotic approximation of the invariant curve near the equilibrium point.

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