The disturbances including harmonics, distortions, transients, fluctuations, and dc offsets in the grid voltages and uncertain load currents, are the most challenging issues in the scenario of ...renewable sources based energy generating systems integrated to the conventional grid. A three-phase, double stage, grid tied solar photovoltaic based distributed generating (SPVDG) system fulfilling multiple objectives, is presented using an adaptive digital disturbance estimator (DDE) and a peak power tracking scheme. The adaptive DDE has the detection proficiency of all the harmonics and lumped disturbances resulting fundamental component estimation of the periodic signals such as grid voltages and load currents. This system deals with objectives such as reactive power compensation, load balancing, peak solar power extraction, operation at grid voltage sags and swells, estimation of harmonics, dc offsets, disturbances, etc. and their elimination. Moreover, this system ensures the active power flow from the SPVDG system to the local loads as well as the grid through a three-phase voltage source converter (VSC). An adaptive technique is used to adjust the dc-link voltage with respect to the grid voltage variation(s) that is advantageous in terms of losses in the VSC. A Lyapunov function candidate is considered to estimate the gains of the disturbance estimator confirming its parameter convergence. Considering the aforementioned objectives, SPVDG system with the proposed DDE-based control scheme, is simulated using Matlab /Simulink environment and then practically implemented using a prototype developed in the laboratory to confirm its performance under steady and dynamic conditions.
This paper deals with control of a solar-photovoltaic (PV) power-generating system interfaced with the grid. A sliding mode control approach is used for achieving maximum power tracking control of a ...solar-PV array. The Lyapunov function-based control approach is designed and modeled for the dc-ac inverter to serve the functions of an active power injection to the grid, balanced grid currents at unity power factor and load currents harmonics compensation. The proposed approaches eliminate the need of adjustment of system parameters under changing loads and generation scenario. The effectiveness of the proposed control strategies is established using its stability analyses. The performance of the solar-PV power-generating system with the proposed control algorithms is demonstrated using simulation and experimental studies under various operating conditions.
This paper presents a harmonic compensation strategy for a 3‐ϕ grid‐tied solar energy conversion system with leakage current attenuation feature. As parasitic capacitance exists between the solar ...photovoltaic panels with the ground, the deviation in common‐mode voltage compels the probable safety hazards such as electromagnetic interference and harmonics injection in the grid currents. Additionally, the power quality indices of the grid, are exacerbated with the coupling of the non‐linear load. Owing to these issues, a generalized integrator based approach is introduced to ensure the harmonics suppression, power factor correction, leakage current alleviation. Additionally, the grid current distortion limits are ensured within limits in order to comply with the IEEE std. 519. The presented algorithm ensures a robust operation with respect to various anomalies in the grid voltages. Simulation results show the satisfactory response of the harmonics controller even under abnormal operating scenarios including the symmetrical/unsymmetrical faults in the grid side network. In comparison with the traditional algorithms, the harmonic controller suppresses the leakage current and harmonics within restricted limits despite the abnormal conditions. Real‐time simulator results demonstrate the performance of the controller under distinct operating conditions such as load unbalancing, distorted grid voltages, etc.
•In India, water storage towers are present almost everywhere, especially across small towns to rural areas. The storage tanks either utilize diesel powered water pumps or utility grid fed water ...pumps 2. So, a robust control of grid integrated solar photovoltaic-based storage tower water pump system with efficient transitioning between standalone and grid interfaced modes are presented.•A smart control is presented for boost converter based distributed generation (DGS), which provides full control on DC link voltage for both modes of operation at all dynamic load conditions.•To reduce the effect of local loads on power utility system, an enhanced phase-locked loop (EPLL) control is utilized for grid source converter (GSC) in grid control operation.•Full order adaptive speed observer control is implemented for an induction motor water pumping application.
In India, water storage towers are present almost everywhere, especially across small towns to rural areas. The storage tanks either utilize diesel powered or utility grid fed induction motor (IM) water pumps. The large spaces available with water storage towers can be utilized to plant solar PV panel for large storage towers water pumping operation, hence, making a switch from diesel or grid run storage towers to solar operated storage towers. This paper presents a robust control of grid integrated solar PV-based water pump system with efficient and smooth transition between standalone and grid interfaced modes. A smart DC link voltage control is presented for distributed generation system (DGS), which provides full control on DC link voltage for both modes of operation at all dynamic load conditions. An enhanced phase-locked loop (EPLL) control is utilized for grid source converter (GSC) in grid control operation, making it flexible to different grid scenarios and power quality. It works for harmonics suppression, load balancing and grid side converter control. An enhanced phase-locked loop (EPLL) is implemented for synchronization control algorithm, which provides an accurate estimation of voltage angle even during frequency ramps and exhibiting superior performance particularly in terms of robustness against DC offsets. The primary requirement for smooth operation of grid-tied solar PV system is effective power management between different sources. The issues of power management and power quality, are discussed in this work, and solutions are presented. The implemented control algorithms are tested successfully for dynamic solar insolation, varying load conditions, unbalance in load, sudden grid outage condition. The system appropriateness is validated by experimental results.
A new modular transformer based 36‐pulse ac–dc converter for a cascaded H‐bridge‐inverter fed medium voltage induction motor drive is proposed in this work. The conventional multi‐pulse ac–dc ...converter has only 18‐pulses in its line input current with six output dc voltages, whereas, the proposed multi‐pulse ac–dc converter has 36‐pulses in its line current with six output voltages. Due to this, the proposed medium voltage induction motor drive has improved power quality at input end. A 9‐level cascaded H‐bridge‐inverter is applied on drive side to boost the performance of medium voltage induction motor drive. A modified model reference adaptive system based speed sensorless vector control is presented in this paper. A nearest level modulation scheme is used to operate a 9‐level inverter at fundamental frequency switching over the entire speed range of an induction motor drive. The performance of this drive is verified through both simulation and experimental results.
•Cellulose acetate–tin (IV) phosphate nanocomposite (CA/TPNC) was prepared.•The CA/TPNC was explored for antibacterial activities against E. coli bacteria.•CA/TPNC was found to be highly selective ...for Cd2+.
Cellulose acetate–tin (IV) phosphate nanocomposite (CA/TPNC) was prepared using simple method at 0–1 pH. The nanocomposite ion exchanger was characterized using some techniques such as Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA/DTA/DSC). The nanocomposite material was explored for different properties such as ion exchange capacity, pH titration, elution behavior, thermal stability, and distribution coefficient. The ion exchange capacity of CA/TPNC was found higher compared to their inorganic counterpart. The distribution coefficient studies of nanocomposite ion exchanger were investigated for different metal ions. On the basis of distribution coefficient studies CA/TPNC material was found more selective for Cd2+ and Mg2+. CA/TPNC ion exchange was explored for antibacterial activities against E. coli bacteria.
This work is focused on a new power quality improved battery charger for electric vehicle using a two switch power factor correction (PFC) single‐ended primary inductance converter (SEPIC) at the ...front‐end followed by a flyback converter. The single‐ended primary inductance converter is a high step‐up PFC converter with a switched inductor configuration at the input. Over a conventional single‐ended primary inductance converter, this new configuration operates with reduced duty ratio for a given DC‐link voltage. By using few additional components, this new single‐ended primary inductance converter offers reduced switch voltage stress to produce the same DC‐link voltage. The operation at lower duty cycle, gives the improved efficiency over a conventional SEPIC PFC converter. The built‐in advantage of soft switching in devices, is achieved due to discontinuous conduction mode based design for both power factor correction converter and flyback converter. The power quality improvement in charger is validated at steady state as well as under variation in input voltage and DC‐link voltage, to meet the IEC 61000‐3‐2 regulations. Performance of this charger is verified in constant current mode with high step‐up gain of power factor correction converter and lower stress across the devices over a conventional single‐ended primary inductance configuration.
•Less number of windings: only one transformer has a single extended delta winding and the remaining windings are a star or delta connection, which makes this system less bulky, and low weight in ...comparison to the 24-pulse converter configuration of 9-13.•Low complexity: the star and delta connections are utilized. Hence, it undoubtedly reduces the complexity of the transformers in comparison to the 24-pulse converter configuration of 9-13.•A new configuration of a 24-pulse converter is presented to overcome the issue at the grid end of the drive system.•Five-level inverters is designed with a reduced number of switches and do not require additional diode, and electrolyte capacitors as 17-25.•Both converters effectively alleviate power quality and harmonic profile within the standard limits.
This paper deals with a reliable transformer configuration with simple wiring and less number windings for twenty-four pulse AC-DC converter, which is used in medium voltage drive system so that it can adverse the effects produced by harmonics currents fed into the grid by converters that do not affect other consumers connected to the same electrical grid. Apart from this, a five-level symmetrical multilevel inverter configuration is used by cascading four two-level voltage source inverters. It is designed with less quantity of components counts like; power switches, diodes and electrolytic capacitors. Because power quality impacts the suitability of electrical power for consumer electronics, an attempt is made in this work to improve power quality through the connecting high-pulse converter at the grid end instead of 12-pulse and modified level-shifted pulse width modulation for a multi-level inverter at the drive end. Performance of the described topology is verified in the laboratory using a drive-through MATLAB/Simulink environment and a prototype at a reduced scale. The feasibility and effectiveness of the proposed topology are demonstrated by a comprehensive comparison with recently reported schemes. Promising results validate this new concept.
A new control strategy for a wind‐BES (battery energy storage) microgrid is presented, which controls the power transfer and the mode of operation seamlessly from an islanded mode (IM) to the grid ...connected mode (GCM) and vice versa. In GCM, the DC link voltage regulation, the load reactive power compensation and harmonics current mitigation are performed by the load side voltage source converter (LVSC) using a double sinusoidal signal integrator (DSSI) based control algorithm. The maximum power from the wind generation is extracted by operating the generator side voltage source converter (GSC). At the grid fault or grid disturbances, this microgrid operates in IM and LVSC is controlled in the voltage control mode. A synchronizing controller is utilized to control the operation of synchronization. The grid current and point of common coupling (PCC) voltage distortions are kept within the limit as per the IEEE‐519‐2014 and the IEEE‐1547 standards. The system operation is demonstrated through test results at several conditions such as, changing wind speeds, varying loads and seamless transition.
Diagnosis and monitoring the condition of induction machines and supply system is critical for industries. Incipient fault detection has received reasonable attention in recent years. In this paper, ...a method based on complex wavelets is proposed for incipient fault detection and condition monitoring. A complex wavelet-support vector machine (SVM) classifier-based method is developed which takes into account four conditions: healthy, turn fault (TF) under balanced supply conditions, voltage imbalance, and interturn fault with voltage imbalance, both occurring at the same time. The performance metrics show the ability of the technique to identify the fault at an early stage and it also provides additional information regarding which of the four conditions is prevailing at a given time. Voltage imbalance and turn fault are often confused. Both affect the performance of the machine and the unbalanced voltage condition considerably reduces the winding insulation life due to overheating. This necessitates the precise identification of the supply condition along with the fault diagnosis. A comparison of the proposed method with standard discrete wavelet transform (DWT) shows its effectiveness in providing reliable information under variable supply-frequency conditions. The proposed technique is also tested in presence of high resistance connections (HRCs), which shows its isolating capability.
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