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In this paper a wavelet packet transform (WPT) based islanding recognition algorithm for utility-grid coupled PV inverter is proposed. The current signal is retrieved at the point of common coupling (PCC). The one cycle post islanding current samples is passed through the WPT, which decomposes into different levels. These levels are grouped jointly to give various frequency sub-bands. Then, the islanding detection signal (IDS) is computed and calculates standard deviation (STD) to identify the islanding condition. The suitable threshold (THD) is selected from STD. The STD value above THD describes the islanding condition. The proposed algorithm is tested on a utility-grid interfaced PV system (UGIPVS) and developed in MATLAB/Simulink software with different conditions. Furthermore, different active and reactive power mismatches cases are validated with the proposed islanding detection signal algorithm. This method provides precise and quick detection of islanding.

Islanding detection is a major concern for utility-grid interfaced photovoltaic power generation systems due to workers and equipment safety issues. To detect the passive islanding scenario, this paper presents the design and development of over/under voltage protection (OVP/UVP) and over/under frequency protection (OFP/UFP) schemes for utility-grid interfaced PV inverters. To track parameters at the Point of Common Coupling (PCC), such as voltage and frequency, and then turn off the inverter when the transition from normal defined conditions is successful. The Non-detection Zone (NDZ) is derived. The MATLAB/Simulink environment is used to develop for utility-grid interfaced PV system. Different active and reactive power mismatches are used to validate the proposed OVP/UVP and OFP/UFP protection schemes using extensive simulation studies.

Industrial electricity users steadily expressed concern about energy efficiency in recent years. Modern enterprises use sensitive electronic power devices, control systems and nonlinear charges to improve energy efficiency and productivity as part of automated processes. Due to the greater use in industrial systems of advanced and sensitive electronic equipment, voltage disruptions have become the most important concern for power quality. A new device that defends sensitive industrial loads against voltage slopes / swells and other stress disruptions is the Dynamic Voltage Restorer (DVR). DVR configurations and control schemes are determined by the specification and characteristics of the load to be protected. Due to the inherent inertia and the ability of induction engines to withstand shorter-term, shallower swells and their phase-angle-hop resistance, induction motor cargo industries need a completely new approach to designing and operating a suitable DVR. This paper proposes a DVR with a quick response, simple and effective controller to satisfy the voltage repair requirements for induction drive applications.

In this paper, a modified three-phase synchronous reluctance motor model based on stator-fluxes and rotor-fluxes in synchronously rotating reference frame is presented. Being a nonlinear system, three-phase synchronous reluctance motor state estimation is carried out using extended Kalman filter. Additionally, parameter sensitivity analysis is performed to convey which parameter is critical in case of actual motor and model parameters mismatch. Extensive simulation studies are performed under different machine operating conditions and machine model uncertainties. The simulation studies are verified on a 5.5 kW synchronous reluctance motor using MATLAB software. The validity and effectiveness of the proposed model is verified by simulation results.

When a fault occurs in the Radial Distribution System, it may take some time to repair the faulted section, and there is no supply to the rest of the sections which are connected to the faulted section until it is repaired. Therefore, the problem of service restoration is an important task in distribution systems. Service must be restored to out-of-service areas by connecting the isolated sections to the other feeders. This can be done by changing the status of the switches between the zones. The generalized algorithms for the problem of service restoration in distribution systems during a fault at a particular zone were developed using Breadth-First Search are tested on a practical test distribution system. The effectiveness of the proposed Breadth-First search method in terms of computational burden is the efficacy of the presented strategy.

This paper presents a Generalized MPPT control based DC-DC boost converter to generate continuous power with its preserved dynamic control system. The PV array is modeled with algebraic loop to achieve accurate solution with iterations in large sample of times. The larger time steps are utilized in this model to obtain fast simulation. MPPT controller embedded with Generalized P and O technique in PV system to regulate duty cycle through which maximum continuous power will be obtained. The MPPT controller with proposed converter is designed in a strategy to extract continuous power regardless of irradiance and temperature. 100kW PV array connected 25kV utility grid is examined in MATLAB SIMULINK and compared with other models in available literature to show effectiveness of designed model.

Multilevel inverter plays a crucial role in industrial applications. The performance of cascaded multilevel inverter (CMLI) with reduced switch count is analyzed in this paper. If the switches have been increased the switching loss and THD will increase. The preferred topology is simulated for seven level and fifteen level by considering isolated DC source and PV. The reduced % THD is identified compare to other topologies. Four switches continuously working at fundamental switching frequency is considered as one of the advantage of the topology.

A novel model-based strategy for bearing fault detection in induction motor is presented. The proposed technique is based on state estimation of induction motor using non-linear derivative free kalman filter. Non-invasive fault detection is the critical advantage of the proposed strategy. The method is robust towards unbalanced supply and variable speed. Analytical computations are carried on 4 hp squirrel-cage induction motor using MATLAB software for different bearing faults. The presented simulation results are validated using auto correlation coefficients. Additionally, the proposed strategy provides better estimates for all types of bearing faults.

This paper presents new passive islanding detection methods for a grid-connected PV (GCPV) system. In the first proposed approach, the 3-phase voltage (p.u) at the point of common coupling (PCC) is extracted and calculates the mean voltage samples. This is passed through the wavelet transform, decomposed up to the level-6(d6) coefficient and then it obviously localizes the event and as a result detects the islanding condition. Finally, to calculate the energy and standard deviation (STD) at level-6(d6) for 2-cycles mean voltage samples it will discriminate islanding condition from the non-islanding condition. The second proposed approach, the negative sequence voltage is considered at PCC. This is passed through the wavelet transform and successfully detects the islanding state. This method also calculates the energy and standard deviation (STD) at level-4(d4) for one cycle of negative sequence voltage it will discriminate islanding situation from the non-islanding situation. The proposed passive methods are tested on a GCPV system with islanding and non-islanding (normal operation and abrupt load change) situation. These techniques are turn out the extremely successfully in islanding detection at PCC for GCPV system. The test GCPV system and simulations are developed in MATLAB/Simulink Software.

In recent years multilevel inverters have been extensively worn in high voltage and high power applications for their unique performance. Reliability of the power electronic equipment is very essential to make sure that inverter operation should be stable and it is most important to detect and locate the faults as speedily as possible. This paper deals with open switch-fault finding method in a multilevel inverter using wavelet transformation tool. A fault diagnosis procedure is proposed and executed using MATLAB.

Many slip-ring induction motor (SRIM) models are found in the literature. In this paper, new extended state-space slip-ring induction motor models are developed using reference frame theory. All these SRIM models are investigated regarding their diagnostic relevance to rotor turn-to-turn short-circuit fault. Ability to generate distinct residuals is important for any model-based fault diagnostics. The performance of these models in term of their capability to detect a fault is compared and best-suited models are recommended based on discriminatory ability index presented in this paper. Analytical computations are carried out for a 4- hp four-pole slip-ring induction motor using MATLAB software. Simulation results are presented to illustrate and validate the proposed index.

Induction machines are extensively used electrical machines in industrial applications. Now-a-days, energy efficient high power rated electrical drives are attracted by industries. Multi-level inverter fed induction motor drives provide a good solution for energy efficient drives. In multilevel inverters due complexity of switching patterns, there is more chance of fault occurring situations. For incipient fault detection, model based methods are gaining importance now-a days. In this paper, state estimation for cascaded hybrid Multilevel inverter fed induction motor using derivative-free extended Kalman filter is presented. With ready available current sensors, the proposed method is very effective for estimating dynamic behaviour of the induction motor drive. Additionally, the technique is very effective for accurate fault detection. Extensive simulation studies are performed on 3.7 kW induction motor using Matlab/Simulink 2016a environment. The presented results validates that proposed methodology can be used in realistic applications.

In the modern industrial drive system, power electronic converters are employed not only to control the electromechanical energy conversion process, but also facilitate energy efficiency and continued automation. In the drive system, induction motor (IM) is a preferred energy conversion device because of its inherent features. Nowadays, power converters using MLI’s playing vital role in the energy conversion process also multilevel configuration allow raising the power-handling capability of the system. Thus, in this paper fifteen level cascaded MLI fed closed loop V/f controlled IM drive is developed and its performance indicators have been analyzed for multicarrier carrier PWM strategy executed using MATLAB/Simulink.

Many wound rotor induction motor models are available in the literature. In this paper, a modified extended wound rotor induction motor model using reference frame theory is presented. State estimation of the proposed WRIM model is carried out using discrete-time extended Kalman filter (DTEKF). Rotor current sensors are required for state estimation which are usually present in all WRIM applications. Analytical simulations are carried out for a 3.7 kW four-pole wound rotor induction motor using MATLAB scientific environment-version R2016a. The results show the advantage of the proposed state estimation in realistic applications from the rotor prospective.

Many induction motor models are available in the literature for modeling, simulation, control as well as fault diagnosis. In this paper, novel induction motor models are formulated based on stationary, rotor and synchronously rotating reference frames. All these proposed models are compared and analyzed in terms of their diagnostic relevance to stator inter-turn faults. Ability to generate distinct residual signatures is a key for model-based diagnostics. Performance of these models in term of their ability to diagnose a fault is compared and best suited models are suggested based on a discriminatory ability index proposed in this paper. As continuous-time extended Kalman filter (CTEKF) is the most commonly used estimator for state estimation, the same has been considered. Computer simulations are carried out for a 4-hp squirrel-cage induction motor using MATLAB. The results prove that all induction motor models do not perform equally well when it comes to fault diagnosis.

In this paper, a novel model-based method for induction motor with stator inter-turn short-circuit fault detection is presented. The proposed technique is based on the whiteness of innovation sequence developed by the standard extended Kalman filter. Nonlinear Generalized Likelihood Ratio method is applied to identify the faulty phase along with its severity. This technique just requires current sensors which are available in most induction motor drive systems to provide good controllability, and induction motor design details are not necessary. Computer simulations are carried out for a 4-hp squirrel cage induction motor using MATLAB environment. The results show the superiority of the proposed method as it provides better estimates for stator interturn fault detection.