ABSTRACT : This paper presents the application of a fuzzy logic controller to improve the stabili... more ABSTRACT : This paper presents the application of a fuzzy logic controller to improve the stability of electric power sys-tem. The stabilising signal is computed using the standard fuzzy membership hnction depending on the speedacceleration state of the generator in the phase plane. ...
Implementation and experimental test results of a neural adaptive power system stabilizer (NAPSS)... more Implementation and experimental test results of a neural adaptive power system stabilizer (NAPSS) are presented in this paper. The digital control system is composed of a micro-alternator, a programmable logic controller (PLC) acting as AVR, a data acquisition system, a PC-based man-machine-interface (MMI) routine and a digital signal processor (DSP) board as the controller. The proposed NAPSS has been tested
The current spike comparator for line protection is based on the comparison of the sign of fault ... more The current spike comparator for line protection is based on the comparison of the sign of fault spikes extracted using discrete wavelet transform (DWT) at both line ends. In this paper, experimental investigation of the current spike comparator is presented. The scheme has been experimentally tested for various fault types covering wide range of fault location, fault resistance, fault inception angle, power swing and switching operations. A digital signal processing (DSP)-based setup is employed in the experimental phase of the study and results are compared with the simulation records. The results showed that, there is some constraints that affect the spike size especially in real-time such as inception angle, high impedance faults, mother wavelet, line model, and channel noise. This scheme is suitable for short transmission lines (R-L mutually coupled model). However, performance is further reduced for long transmission lines (distributed parameter model)
... Then, the spectral energies (expressed in the current square) of Idif and Iav are computed us... more ... Then, the spectral energies (expressed in the current square) of Idif and Iav are computed using the moving average window to obtain the operating signal (EIop) and restraining one (EIre), which are given by: ... 2.a and the fault is discriminated as internal fault since EIop>EIre. ...
Feature extraction plays a key role in fault diagnosis of rotating machinery. Many methods report... more Feature extraction plays a key role in fault diagnosis of rotating machinery. Many methods reported in the literature are based on masses of labeled data and need much prior knowledge to select the most discriminating features or establish a complex deep-learning model. To solve the dilemma, a novel feature extraction method based on kernel principal component analysis (KPCA) and an autoencoder (AE), namely, SFS-KPCA-AE, is presented in this paper to automatically extract the most discriminative features from the frequency spectrum of vibration signals. First, fast Fourier transform is calculated on the entire vibration signal to get the frequency spectrum. Next, the spectrum is divided into several segments. Then, local-global feature extraction is performed by applying KPCA to these segments. Finally, an AE is employed to obtain the low-dimensional representations of the high-dimensional global feature. The proposed feature extraction method combined with a classifier achieves fau...
In this paper a systematic method of choosing the frequency bias parameter and the integrator gai... more In this paper a systematic method of choosing the frequency bias parameter and the integrator gain of the sam¬ pled data supplementary control is presented by using the discrete version of the Lyapunov technique. The reheat effect of the steam turbines is considered in the state space model. The effect of governor deadband nonlinearity is considered by using the describing function approach and including the linearized equations in the state space model. It is shown that the governor dead-band nonlinearity has a destabilizing effect on the transient response with deterministic and random load disturbances for purely integral ACE control. However, this destabilizing effect is reduced by proportional feedback of ACE.
Proceedings of 1996 Canadian Conference on Electrical and Computer Engineering
Thermal models can be used to protect induction motors from excessive overheating resulting from ... more Thermal models can be used to protect induction motors from excessive overheating resulting from overloading, failure to start, unbalance and frequent starting. Such a model is adopted for use in a relaying algorithm. The developed algorithm accurately calculates the change in motor temperature and hence, protects the motor from excessive overheating. The lab results, included in this paper, of motor
2006 IEEE Power Engineering Society General Meeting, 2006
New problems emerging from the increased production of power from renewable resources are becomin... more New problems emerging from the increased production of power from renewable resources are becoming a good challenge. To face the new challenges, accurate modeling of such systems is required. For example, to be able to apply advanced control strategies, usually a linearized state space representation of the system is needed. Taking a variable speed cage machine wind generation system as
IEEE Transactions on Power Apparatus and Systems, 1973
Page 1. DIGITAL CONTROL SCHEME FORA GENERATING UNIT KJ Runtz, ASA Farag, DWHuber, GS Hope, 0. P. ... more Page 1. DIGITAL CONTROL SCHEME FORA GENERATING UNIT KJ Runtz, ASA Farag, DWHuber, GS Hope, 0. P. Malik ... This in turn has contributed to the appearance onthe market of themini-computer, the cost of which has been drastically reduc-ed over the past few years. ...
2009 IEEE/PES Power Systems Conference and Exposition, 2009
An experimental evaluation of a power differential relay is conducted and the results are describ... more An experimental evaluation of a power differential relay is conducted and the results are described. The experimental setup consists of a generator connected to the network via a transmission line protected by the power deferential relay. The relay input signals, fundamental active and reactive powers, are locally computed from the complex product of the current and voltage phasors at each
2013 26th IEEE Canadian Conference on Electrical and Computer Engineering (CCECE), 2013
ABSTRACT Characteristics of a small scale wind turbine using Permanent Magnet Synchronous Generat... more ABSTRACT Characteristics of a small scale wind turbine using Permanent Magnet Synchronous Generator and connected to a grid through a reduced switches count converter (two legs only) are studied in this paper. Active power output corresponding with the input is given with the reactive power produced by the wind turbine regulated at 0 MVAr. Variable wind speed is optimum for drive train performance at 10 m/s (at maximum power coefficient point). When wind speed changes, the turbine moves away from its optimal tip speed ratio until maximum power point tracking forces the turbine to operate at its optimal speed. The generator torque is regulated by controlling the generator current based on the principle of field oriented control where a decoupling between the field and torque current components is achieved. The generator reference voltage and the converter switching signals are synthesized using the principle of space vector modulation. A 5.7 kW grid-connected variable speed wind turbine is simulated using Matlab/Simulink to study the feasibility of the proposed control technique.
International Journal of Surface Mining, Reclamation and Environment, 1987
The paper presents a relatively new method of sizing the distribution electrical equipment used t... more The paper presents a relatively new method of sizing the distribution electrical equipment used to supply groups of excavators working in open-pit mines. In particular, the problem of sizing of impact-loaded transformers is discussed and an appropriate algorithm is given. The theoretical background of the method is outlined with reference to the earlier works of the authors. An illustrative example of the method application is given.
The application of differential dynamic programming or hybrid quasilinearization technique to the... more The application of differential dynamic programming or hybrid quasilinearization technique to the solution of non-linear optimization problems in .power systems has encountered the problem of computational instability, particularly in higher order systems. This paper describes the application of a continuation procedure to alleviate this difficulty. Sixth order non-Iinear systems have been optimized with and without constraints on control variables. Both open-loop and, for the first time, closed-loop systems including both exciter and governor dynamics, are analysed. The studies presented show that this techniquo is quite effective in obtaining accurate solutions for non-linear boundary-value-problems in power systems.
System identification plays an extremely important role in the self-tuning controller. As the rec... more System identification plays an extremely important role in the self-tuning controller. As the recursive least squares (RLS)identification technique has the advantages of simple calculation and good convergence properties, it is the preferred technique for use in the design of the self-tuning controllers. However, use of RLS identification in a real-time environment does raise some problems such as the speed of parameter convergence, identification going to ‘sleep’, covariance matrix ‘blow up’, biased identification, etc. This paper deals with the problems which may arise in the practical use of the RLS identification technique. These issues are the summary of several years' experience of designing self-tuning controllers with RLS identification technique for power system applications. Although some of these issues are difficult to analyse, they are quite effective in dealing with the practical problems.
Power systems are non-linear: the structure and parameters of a network are time varying and cann... more Power systems are non-linear: the structure and parameters of a network are time varying and cannot be represented accurately by a linear model under all operating conditions. In addition power system disturbances are random in nature, therefore self-tuning controllers are more suitable for power system control than constant parameter linear controllers. The non-minimum phase nature of power systems prohibits the use of simple minimum-variance self-tuning controllers. Generalized minimum variance control can be used to overcome this difficulty. Using multi-input multi-output (MIMO) control, the control efforts of both the excitation and governor systems can be coordinated to improve dynamic stability. The objective of this paper is to present the results obtained from simulation studies in which the MIMO generalized minimum variance control, with square-root least-squares identification and variable forgetting factor, is used to improve the damping of the power system oscillations.
The ability of a dual-rate adaptive stabilizer to damp multimode oscillations in a power system i... more The ability of a dual-rate adaptive stabilizer to damp multimode oscillations in a power system is investigated. The controller adjusts its parameters to track the dominant frequency of oscillation and damps different modes one by one according to their dominance. The results show that adaptive and conventional stabilizers working on different units within a system can operate cooperatively and mutually
An adaptive synchronous machine controller that minimizes a cost function incorporating system in... more An adaptive synchronous machine controller that minimizes a cost function incorporating system input, output, and set-point variations, and its application to a multi-machine power system are described in this paper. The control is based on a criterion of automatically shifting the closed loop poles of the system towards the origin in the z-domain without violating the control constraints. It possesses the property of robustness and eqse of reference signal tracking. The ability of the proposed controller to damp multi-mode oscillations is investigated. Studies show that the proposed controller cooperates with the conventional power system stabilizers on the system in damping the oscillations.
A transmission line distance relaying technique using an on-line trained neural network (NN) is d... more A transmission line distance relaying technique using an on-line trained neural network (NN) is developed. Results of numerical simulation and experimental studies show very good accuracy and fast estimation of distance to fault for various faults under different operating conditions, high fault resistance, and remote-end feed.
ABSTRACT : This paper presents the application of a fuzzy logic controller to improve the stabili... more ABSTRACT : This paper presents the application of a fuzzy logic controller to improve the stability of electric power sys-tem. The stabilising signal is computed using the standard fuzzy membership hnction depending on the speedacceleration state of the generator in the phase plane. ...
Implementation and experimental test results of a neural adaptive power system stabilizer (NAPSS)... more Implementation and experimental test results of a neural adaptive power system stabilizer (NAPSS) are presented in this paper. The digital control system is composed of a micro-alternator, a programmable logic controller (PLC) acting as AVR, a data acquisition system, a PC-based man-machine-interface (MMI) routine and a digital signal processor (DSP) board as the controller. The proposed NAPSS has been tested
The current spike comparator for line protection is based on the comparison of the sign of fault ... more The current spike comparator for line protection is based on the comparison of the sign of fault spikes extracted using discrete wavelet transform (DWT) at both line ends. In this paper, experimental investigation of the current spike comparator is presented. The scheme has been experimentally tested for various fault types covering wide range of fault location, fault resistance, fault inception angle, power swing and switching operations. A digital signal processing (DSP)-based setup is employed in the experimental phase of the study and results are compared with the simulation records. The results showed that, there is some constraints that affect the spike size especially in real-time such as inception angle, high impedance faults, mother wavelet, line model, and channel noise. This scheme is suitable for short transmission lines (R-L mutually coupled model). However, performance is further reduced for long transmission lines (distributed parameter model)
... Then, the spectral energies (expressed in the current square) of Idif and Iav are computed us... more ... Then, the spectral energies (expressed in the current square) of Idif and Iav are computed using the moving average window to obtain the operating signal (EIop) and restraining one (EIre), which are given by: ... 2.a and the fault is discriminated as internal fault since EIop>EIre. ...
Feature extraction plays a key role in fault diagnosis of rotating machinery. Many methods report... more Feature extraction plays a key role in fault diagnosis of rotating machinery. Many methods reported in the literature are based on masses of labeled data and need much prior knowledge to select the most discriminating features or establish a complex deep-learning model. To solve the dilemma, a novel feature extraction method based on kernel principal component analysis (KPCA) and an autoencoder (AE), namely, SFS-KPCA-AE, is presented in this paper to automatically extract the most discriminative features from the frequency spectrum of vibration signals. First, fast Fourier transform is calculated on the entire vibration signal to get the frequency spectrum. Next, the spectrum is divided into several segments. Then, local-global feature extraction is performed by applying KPCA to these segments. Finally, an AE is employed to obtain the low-dimensional representations of the high-dimensional global feature. The proposed feature extraction method combined with a classifier achieves fau...
In this paper a systematic method of choosing the frequency bias parameter and the integrator gai... more In this paper a systematic method of choosing the frequency bias parameter and the integrator gain of the sam¬ pled data supplementary control is presented by using the discrete version of the Lyapunov technique. The reheat effect of the steam turbines is considered in the state space model. The effect of governor deadband nonlinearity is considered by using the describing function approach and including the linearized equations in the state space model. It is shown that the governor dead-band nonlinearity has a destabilizing effect on the transient response with deterministic and random load disturbances for purely integral ACE control. However, this destabilizing effect is reduced by proportional feedback of ACE.
Proceedings of 1996 Canadian Conference on Electrical and Computer Engineering
Thermal models can be used to protect induction motors from excessive overheating resulting from ... more Thermal models can be used to protect induction motors from excessive overheating resulting from overloading, failure to start, unbalance and frequent starting. Such a model is adopted for use in a relaying algorithm. The developed algorithm accurately calculates the change in motor temperature and hence, protects the motor from excessive overheating. The lab results, included in this paper, of motor
2006 IEEE Power Engineering Society General Meeting, 2006
New problems emerging from the increased production of power from renewable resources are becomin... more New problems emerging from the increased production of power from renewable resources are becoming a good challenge. To face the new challenges, accurate modeling of such systems is required. For example, to be able to apply advanced control strategies, usually a linearized state space representation of the system is needed. Taking a variable speed cage machine wind generation system as
IEEE Transactions on Power Apparatus and Systems, 1973
Page 1. DIGITAL CONTROL SCHEME FORA GENERATING UNIT KJ Runtz, ASA Farag, DWHuber, GS Hope, 0. P. ... more Page 1. DIGITAL CONTROL SCHEME FORA GENERATING UNIT KJ Runtz, ASA Farag, DWHuber, GS Hope, 0. P. Malik ... This in turn has contributed to the appearance onthe market of themini-computer, the cost of which has been drastically reduc-ed over the past few years. ...
2009 IEEE/PES Power Systems Conference and Exposition, 2009
An experimental evaluation of a power differential relay is conducted and the results are describ... more An experimental evaluation of a power differential relay is conducted and the results are described. The experimental setup consists of a generator connected to the network via a transmission line protected by the power deferential relay. The relay input signals, fundamental active and reactive powers, are locally computed from the complex product of the current and voltage phasors at each
2013 26th IEEE Canadian Conference on Electrical and Computer Engineering (CCECE), 2013
ABSTRACT Characteristics of a small scale wind turbine using Permanent Magnet Synchronous Generat... more ABSTRACT Characteristics of a small scale wind turbine using Permanent Magnet Synchronous Generator and connected to a grid through a reduced switches count converter (two legs only) are studied in this paper. Active power output corresponding with the input is given with the reactive power produced by the wind turbine regulated at 0 MVAr. Variable wind speed is optimum for drive train performance at 10 m/s (at maximum power coefficient point). When wind speed changes, the turbine moves away from its optimal tip speed ratio until maximum power point tracking forces the turbine to operate at its optimal speed. The generator torque is regulated by controlling the generator current based on the principle of field oriented control where a decoupling between the field and torque current components is achieved. The generator reference voltage and the converter switching signals are synthesized using the principle of space vector modulation. A 5.7 kW grid-connected variable speed wind turbine is simulated using Matlab/Simulink to study the feasibility of the proposed control technique.
International Journal of Surface Mining, Reclamation and Environment, 1987
The paper presents a relatively new method of sizing the distribution electrical equipment used t... more The paper presents a relatively new method of sizing the distribution electrical equipment used to supply groups of excavators working in open-pit mines. In particular, the problem of sizing of impact-loaded transformers is discussed and an appropriate algorithm is given. The theoretical background of the method is outlined with reference to the earlier works of the authors. An illustrative example of the method application is given.
The application of differential dynamic programming or hybrid quasilinearization technique to the... more The application of differential dynamic programming or hybrid quasilinearization technique to the solution of non-linear optimization problems in .power systems has encountered the problem of computational instability, particularly in higher order systems. This paper describes the application of a continuation procedure to alleviate this difficulty. Sixth order non-Iinear systems have been optimized with and without constraints on control variables. Both open-loop and, for the first time, closed-loop systems including both exciter and governor dynamics, are analysed. The studies presented show that this techniquo is quite effective in obtaining accurate solutions for non-linear boundary-value-problems in power systems.
System identification plays an extremely important role in the self-tuning controller. As the rec... more System identification plays an extremely important role in the self-tuning controller. As the recursive least squares (RLS)identification technique has the advantages of simple calculation and good convergence properties, it is the preferred technique for use in the design of the self-tuning controllers. However, use of RLS identification in a real-time environment does raise some problems such as the speed of parameter convergence, identification going to ‘sleep’, covariance matrix ‘blow up’, biased identification, etc. This paper deals with the problems which may arise in the practical use of the RLS identification technique. These issues are the summary of several years' experience of designing self-tuning controllers with RLS identification technique for power system applications. Although some of these issues are difficult to analyse, they are quite effective in dealing with the practical problems.
Power systems are non-linear: the structure and parameters of a network are time varying and cann... more Power systems are non-linear: the structure and parameters of a network are time varying and cannot be represented accurately by a linear model under all operating conditions. In addition power system disturbances are random in nature, therefore self-tuning controllers are more suitable for power system control than constant parameter linear controllers. The non-minimum phase nature of power systems prohibits the use of simple minimum-variance self-tuning controllers. Generalized minimum variance control can be used to overcome this difficulty. Using multi-input multi-output (MIMO) control, the control efforts of both the excitation and governor systems can be coordinated to improve dynamic stability. The objective of this paper is to present the results obtained from simulation studies in which the MIMO generalized minimum variance control, with square-root least-squares identification and variable forgetting factor, is used to improve the damping of the power system oscillations.
The ability of a dual-rate adaptive stabilizer to damp multimode oscillations in a power system i... more The ability of a dual-rate adaptive stabilizer to damp multimode oscillations in a power system is investigated. The controller adjusts its parameters to track the dominant frequency of oscillation and damps different modes one by one according to their dominance. The results show that adaptive and conventional stabilizers working on different units within a system can operate cooperatively and mutually
An adaptive synchronous machine controller that minimizes a cost function incorporating system in... more An adaptive synchronous machine controller that minimizes a cost function incorporating system input, output, and set-point variations, and its application to a multi-machine power system are described in this paper. The control is based on a criterion of automatically shifting the closed loop poles of the system towards the origin in the z-domain without violating the control constraints. It possesses the property of robustness and eqse of reference signal tracking. The ability of the proposed controller to damp multi-mode oscillations is investigated. Studies show that the proposed controller cooperates with the conventional power system stabilizers on the system in damping the oscillations.
A transmission line distance relaying technique using an on-line trained neural network (NN) is d... more A transmission line distance relaying technique using an on-line trained neural network (NN) is developed. Results of numerical simulation and experimental studies show very good accuracy and fast estimation of distance to fault for various faults under different operating conditions, high fault resistance, and remote-end feed.
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Papers by Om Malik