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This paper proposes a new algorithm based on sensitivity analysis and the Wolfe method to solve a sequence of parametric quadratic programming (QP) problems such as those that arise in quadratic model predictive control (QMPC). The Wolfe method, based on Karush–Kuhn–Tucker conditions, has been used to convert parametric QP problems to parametric linear programming (LP) problems, and then the sensitivity analysis is applied to solve the sequence of the parametric LP problems. This strategy obtains sensitivity analysis‐based QMPC (SA‐QMPC) algorithm. It is proved that the computational complexity of SA‐QMPC is O(Nn2)$O(Nn^2)$ for a region of the initial conditions and O(N2n2)$O(N^2n^2)$ for sufficiently small sampling time and all initial conditions, where N$N$ and n$n$ are the horizon time and dimension of the state vector, respectively. Numerical results indicate the potential and properties of the proposed algorithm. [ABSTRACT FROM AUTHOR]

This study proposes a new method based on sensitivity analysis to solve a series of sequential parametric linear programmings (LPs) such as that those arise in l1 model predictive control l1 (MPC). The main idea is to find a relationship between each of the two successive parametric LPs by using sensitivity analysis strategy. Tolerance analysis-based MPC (TA-l1 MPC) and sensitivity analysis-based MPC (SA-l1 MPC) are introduced for reducing computational complexity and runtime. TA-l1 MPC takes O(Nn²) operations per step time, where N and n are the prediction horizon and the number of states, respectively. This approach is very faster than generic optimisation methods but it can be applied only for initial conditions that are near to steady-state values. SA-l1 MPC has not any limitation in usage and it reduces the runtime significantly compared with common solvers. Finally, numerical results indicate the potential of the proposed algorithms. [ABSTRACT FROM AUTHOR]

This study proposes a new method based on sensitivity analysis to solve a series of sequential parametric linear programmings (LPs) such as that those arise in l1 model predictive control l1 (MPC). The main idea is to find a relationship between each of the two successive parametric LPs by using sensitivity analysis strategy. Tolerance analysis‐based MPC (TA‐ l1 MPC) and sensitivity analysis‐based MPC (SA‐ l1 MPC) are introduced for reducing computational complexity and runtime. TA‐ l1 MPC takes O(Nn2) operations per step time, where N and n are the prediction horizon and the number of states, respectively. This approach is very faster than generic optimisation methods but it can be applied only for initial conditions that are near to steady‐state values. SA‐ l1 MPC has not any limitation in usage and it reduces the runtime significantly compared with common solvers. Finally, numerical results indicate the potential of the proposed algorithms. [ABSTRACT FROM AUTHOR]

A new adaptive scheme for joint time delay and frequency estimation of two sinusoidal signals that are received at two spatially separated sensors is proposed in this paper. The proposed method is based on adding a new mechanism to the existing structure of a second-order generalized integrator. The main feature of the proposed algorithm, which makes it distinguished from some similar works and appealing from a practical viewpoint, is that it does not require any a priori knowledge on the input signal frequency and therefore works at various sampling frequencies. Averaging theory is used to analyze the dynamic behavior of the proposed algorithm. Various simulations are provided to illustrate the effectiveness of the algorithm and to demonstrate the ability of the algorithm to track variations of parameters of the input signals. [ABSTRACT FROM PUBLISHER]

On-line estimation of low-frequency electromechanical oscillations in an interconnected power system has attracted much attention as this provides vital information about the stability condition of the power system. In this paper, a measurement-based method for the estimation of the frequency, magnitude, and damping of an oscillation is proposed. The method can be applied to the phasor measurement data to extract further information about the power system. The proposed method is derived by applying modifications to the existing concept of second-order generalized integrator and adaptive notch filter. This paper details the mathematical derivation and stability properties of the proposed method and presents the simulation results to confirm the analytical derivations and the desirable performance of the proposed method. [ABSTRACT FROM PUBLISHER]

This paper presents a new three-phase phase-locked loop (PLL) system that primarily estimates the phase angles, frequency, and magnitudes of the a three-phase input signal and also provides a filtered version of the input. It is then extended to the estimation of sequence components, their magnitudes, and phase angles. As compared with the conventional three-phase PLL, this method does not suffer from errors that are caused by signal unbalance and dc offset. It also provides estimate for several other variables which are not included in the conventional three-phase PLL. As compared with the method of using three independent single-phase enhanced PLLs, the proposed method offers a simpler structure. Moreover, the estimated frequency is more accurate and smoother because it uses the information from all three phases to estimate a single value for frequency. The paper also presents a modification that makes the PLL parameters independent from the input signal amplitude. The same modification is applicable to existing methods such as conventional three-phase PLL. Simulation and experimental results are presented to confirm desirable performance of the proposed method. [ABSTRACT FROM AUTHOR]

An algorithm based on the concept of an adaptive notch filter is proposed for the frequency estimation of three-phase power signals. The algorithm permits direct estimation of frequency and its rate of change for power system signals. The proposed method uses the information of all three-phase signals together. The structure, mathematical formulation, and theoretical stability analysis of the proposed technique are presented, and its performance is studied in a variety of scenarios where three-phase power signal attributes such as frequency and amplitude undergo variations over time. This study confirms the desirable transient and steady-state performances of the proposed algorithm. In contrast to the conventional three-phase PLL-based frequency estimator, the proposed method is less sensitive to distortions such as harmonics and interharmonics and is not sensitive to unbalanced system conditions. [ABSTRACT FROM AUTHOR]

A method for real-time detection and extraction of individual harmonic and interharmonic components in a power signal with potentially time-varying characteristics is presented. The proposed method, which is based on the concept of adaptive notch filter (ANF), adaptively decomposes the measured power signal into its constituting components independent of where their frequencies are located. The algorithm provides instantaneous values of the various estimated frequency components in addition to the values of their frequencies, amplitudes, and phase angles. The structure and mathematical formulation of the proposed technique, including guidelines for its parameter tuning, are presented and its performance is studied in a variety of scenarios where the power signal attributes, such as fundamental frequency and amplitude, undergo variations over time. This study confirms the desirable transient and steady-state performances of the proposed method. Compared with its recently proposed counterpart, the proposed method of this paper obviates the need for using a phase-locked loop (PLL), and hence, offers a more simplified structure which makes it more attractive from an implementation point of view. [ABSTRACT FROM AUTHOR]

This paper introduces an approach for the real-time extraction of the frequency, phase angle, and symmetrical components of the grid signal, which is of great importance for many applications in power systems such as power quality and protection. The proposed method is based on the concept of the adaptive notch filter that provides a fast and accurate estimation of the symmetrical components in the presence of frequency and amplitude variations. In addition, the system offers a high degree of immunity and insensitivity to power system disturbances, harmonics, and other types of pollutions that exist in the grid signal. The simplicity of the structure makes the method suitable for both software and hardware implementations. Moreover, this very simple and very powerful tool can be used as a synchronization technique, which further simplifies the control issues currently challenging the integration of distributed energy technologies into the electricity grid. Mathematical derivations are presented to describe the principles of operation, and experimental results confirm the validity of the analytical work. [ABSTRACT FROM AUTHOR]

An algorithm based on the concept of adaptive notch filter (ANF) is proposed for estimation of power system frequency. The ANF is a second-order notch filter that is further furnished with a nonlinear differential equation to update the frequency. The method permits direct estimation of frequency and its rate of change for a power system signal. The performance of the algorithm is compared with that of a newly introduced algorithm, which is based on using an enhanced phase-locked loop (PLL) system. Unlike the PLL-based frequency estimator, the proposed algorithm does not employ a voltage-controlled oscillator. This makes its structure much simpler for implementation. The transient response of the proposed estimator is faster than that of the PLL-based estimator. Computer simulations are presented to highlight the usefulness of this approach in estimating near- nominal and off-nominal power system frequencies. [ABSTRACT FROM AUTHOR]

Noise reduction and signal decomposition are among important and practical issues in time-domain signal analysis. This paper presents an adaptive notch filter (ANF) to achieve both these objectives. For noise reduction purpose, the proposed adaptive filter successfully extracts a single sinusoid of a possibly time-varying nature from a noise-corrupted signal. The paper proceeds with introducing a chain of filters which is capable of estimating the fundamental frequency of a signal composed of harmonically related sinusoids, and of decomposing it into its constituent components. The order of differential equations governing this algorithm is 2n + 1, where n is the number of constituent sinusoids that should be extracted. Stability analysis of the proposed algorithm is carried out based on the application of the local averaging theory under the assumption of slow adaptation. When compared with the conventional Fourier analysis, the proposed method provides instantaneous values of the constituting components. Moreover, it is adaptive with respect to the fundamental frequency of the signal. Simulation results verify the validity of the presented algorithm and confirm its desirable transient and steady-state performances as well as its desirable noise characteristics. [ABSTRACT FROM AUTHOR]

The performance of the conventional model predictive current control (MPCC) method is not without steady‐state ripples in electrical drives. Although some recently proposed MPCC methods have succeeded to mitigate this drawback, they have led to reductions in the dynamic speed response inherent to the conventional MPCC method. An improved MPCC is proposed here which would enhance the conventional MPCC method without any side effect on its merits. In this proposed method, three control strategies are presented for transient‐ and steady‐state operations. The first two strategies are applied to improve motor performance in the steady state, through calculating the voltage vector (VV) and its optimal duration to minimise ripples in both d–q ‐axis currents. The third strategy is applied in the transient‐state operation, where, instead of two VVs, an allowable non‐zero VV is applied throughout the control cycle to prevent dynamic response reduction caused by zero VV. The experimental results confirm the effectiveness of this proposed method in reducing torque ripples, flux ripples, and the stator current total harmonic distortion in relation to those obtained by the previous MPCC methods. [ABSTRACT FROM AUTHOR]

Summary: An improved model predictive current control (MPCC) method is developed to be applied to surface‐mounted permanent magnet synchronous motor (SPMSM). Here, three control techniques are applied to increase the control precision in the steady state, while dynamic response is improved in the transient state. In steady state, the two control techniques, d‐ and q‐axes currents control (DQ‐ACC) technique and q‐axis current control (Q‐ACC) technique, are designed to enhance the stator current quality. The appropriate voltage space vector (VSV) is selected through the cost function, which is applied to the motor at an optimal time. Calculation of this optimal time is different for each one of these control techniques where the objective is to achieve an appropriate d‐ and q‐axes current qualities. In transient state, the fast q‐axis current control (FQ‐ACC) technique is designed to obtain a faster dynamic response. The VSV is selected through the cost function and is applied to the motor throughout the control cycle. This proposed control method is implemented on a digital signal processor (DSP) model TM320F28335 to control a 100‐w SPMSM. The experimental test results indicate that these proposed techniques in terms of torque, flux, and stator current quality outperform their counterparts with an appropriate dynamic response. [ABSTRACT FROM AUTHOR]

Recently, the application of the adaptive notch filter (ANF) concept to the analysis of damped oscillations and the estimation of frequency and damping factor of such oscillations was introduced. This paper presents the application of the enhanced phase-locked loop (EPLL) to the same problem. A modified version of the EPLL is developed that includes the estimation of damping factor in addition to the already estimated variables of amplitude, phase angle, and frequency. The structure, mathematical formulation, and theoretical stability analysis of the proposed method, including guidelines for its parameter tuning, are presented. Simulation results verify the analytical derivations and the desirable performance of the proposed method. This paper concludes that the EPLL-based approach can address the problem as efficient as the ANF approach while offering more robust and accurate results at low sampling rate applications. [ABSTRACT FROM AUTHOR]

Estimation of electromechanical modes of a power system has attracted attention in the past few decades because it can provide vital information about the stability of the system. In this paper, a new state-space model is proposed for online detection of parameters of a ringdown signal using an extended Kalman filter (EKF). The proposed model can estimate both constant and time-varying parameters. Furthermore, stability analysis of the proposed model is performed to demonstrate the convergence of the parameters. Simulation results confirm the desirable performance of the proposed method for ringdown parameter estimation. [ABSTRACT FROM PUBLISHER]

This paper is concerned with the problem of full-order H 2 and H ∞ linear parameter varying filter design for continuous-time systems with arbitrarily time-varying parameters. The time-varying parameters belong to a polytope with known vertices, affect all the system matrices and are assumed to be available online for implementation of the filters. The synthesis conditions are formulated in terms of parameter dependent Linear Matrix Inequalities (PDLMIs). A sequence of standard LMI conditions assuring the existence of homogeneous polynomially parameter-dependent (HPPD) solutions to the parameter-dependent LMIs for filter design is provided in terms of the vertices of the polytope yielding parameter dependent filters of arbitrary degree assuring quadratic stability of the error dynamics. By definition of slack variables, extra free dimensions are provided to the parameter dependent filter design optimization problem, so method presented in this paper expected to be less conservative than the existing methods for the polytopic uncertain systems and efficiency of the method for filter design is illustrated by means of numerical comparisons with some benchmark examples from the literature. [ABSTRACT FROM AUTHOR]

Switched linear systems with dwell time constraints constitute a very popular class of switched systems. In this study, impact of uncertain parameters on the stability of Parametrised switched linear (SL) systems with dwell time is investigated. Sufficient conditions are first proposed to analyse the global asymptotic stability of SL systems with dwell time. The conditions are then generalised to the case with parametric uncertainties to determine upper bounds on parametric uncertainties such that robust asymptotic stability is assured under dwell time constraints. Finally, an off‐line computational algorithm is proposed to enlarge the estimated stability intervals. Effectiveness and simplicity of the computations are shown by a numerical example. [ABSTRACT FROM AUTHOR]

This paper presents a new approach for wave filtering and state estimation in regulation and dynamic positioning of marine vessels. In this approach, low-frequency (LF) and wave-frequency (WF) motion components, LF disturbance forces, and vessels velocities devoid of oscillation are estimated from the measured position signals. The proposed system is composed of a modified notch filter and a nonlinear observer. In this method, filtering is independent from the vessel and LF disturbances models, and therefore it is not affected from modeling uncertainty. Furthermore, the proposed structure is furnished with an estimation law of fundamental frequency of WF vessel motion that improves its performance considerably. It is shown that the basic structure is globally exponentially stable and its adaptive version is locally asymptotically stable. Simulations illustrate the desirable performance of the proposed methods, the efficacy of modifications and their comparison with the conventional approach. [ABSTRACT FROM PUBLISHER]

This paper introduces a new three-phase harmonic- decomposition technique to extract voltage/current harmonics for use in grid-connected converters, such as for active power filters (APFs). The main function of this technique is to detect a selective order of harmonics for control purposes. This feature is useful when elimination of certain harmonics is of concern. Moreover, the proposed method can successfully detect and track the variations in the frequency of the signal and extract the time-varying harmonics. A theoretical analysis is presented, and the performance of the method is experimentally evaluated. The methodology is applicable for a wide range of equipment such as uninterruptible power supplies, regenerative converters, APFs, etc., as a basis for the detection of the reference signals. [ABSTRACT FROM AUTHOR]

This paper introduces a new adaptive notch filtering approach to extract the harmonic and reactive current components for power quality purposes in grid-connected converters. The main function of this method is to provide synchronized harmonic and reactive current components for control purposes. The theoretical analysis is presented, and the performance of the method is experimentally evaluated. The methodology is applicable for a wide range of equipment such as uninterrupted power supplies, regenerative converters, active power filters, etc., as a basis for generating the reference signals. [ABSTRACT FROM AUTHOR]