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Base station sleeping (BSS) can result in significant reduction in energy consumption of cellular networks during low traffic conditions. We show that the coverage loss due to BSS can be compensated via coordinated multi-point (CoMP) -based transmission in a cluster of base stations. For a BSS with CoMP-based system, we propose various BSS patterns to achieve suitable trade-offs between energy savings and throughput. We formulate the CoMP resource allocation and $\alpha -$ Fair user scheduling as a joint optimization problem. We derive the optimal time fraction and user scheduling for this problem and use it to formulate a simplified BSS with CoMP optimization problem. A heuristic that solves this problem is presented. Through extensive simulations, we show that suitable trade-offs among energy, coverage, and rate can be achieved by appropriately selecting the BSS pattern, CoMP cluster, and rate threshold.

A temperature compensated under voltage lockout (UVLO) circuit for ultra-low power applications is presented. The UVLO operation is achieved using two transistors with different threshold voltages and a source follower. The difference in the thresholds of the two transistors is used to create a reference voltage. As the supply voltage rises, the generated reference voltage tracks the supply till its designed voltage value and thereafter becomes a constant. This reference voltage is applied to a self-referenced common-source stage and is further amplified by CMOS inverters to arrive at a decision to lock out the supply or not. The designed UVLO consumes 200 pA of current at 1.8 V supply. The measured low-to-high trip points (LHTP) and high-to-low trip points (HLTP) are 1.28 V and 1.12 V with a variability of 208 ppm/°C and 200 ppm/°C respectively. These trip points are programmable from 1.1 V to 1.4 V in steps of 100 mV. The design occupies 0.00723 mm2 in standard 180 nm CMOS.

Cloud radio access networks (C-RAN) and millimeter wave (mmwave) based remote radio heads (RRHs) have been proposed in 5G. Further, dual connectivity (DC) has been introduced in cellular networks to increase the per-user throughput of the system. The implementation of DC requires user’s information to be shared and processed for all the participating RRHs. In this work, we consider DC in C-RAN with mmwave based fronthaul between the virtualized base band unit (BBU) pool and the RRHs. Given a generalized $\alpha$-fair scheduler, the resource allocation problem for the mmwave based fronthaul is formulated for a DC system. The optimal time fraction that the virtualized BBU pool should serves each RRH is analytically derived. Further, the association of DC is numerically solved with this fronthaul resource allocation. Numerical results are presented that indicate that the proposed solution outperforms the existing benchmark in terms of the user throughput for a marginal increase in the required fronthaul capacity.

In multiphase induction motors the number of slots per pole per phase comes down due to the higher number of phases, which results the airgap MMF per phase closer to square wave. In addition, as the number of poles increases the space harmonics will increase further in Pole-phase modulated induction motor drives (PPMIM) drives. To address this issues, in this paper a distributed short pitch winding (DSPW) is proposed for PPMIM drives. In DSPW, the number of conductors per phase are distributed over three stator slots that will generate the multi-stepped MMF wave in airgap as compared to concentrated winding. Because of this, the space harmonics in the airgap as well as the harmonics in induced EMF will come down, which improves the performance of the drive. The PPMIM drive with proposed DSPW, is capable to operate in 9-phase 2-pole mode and 3-phase 6-pole mode without changing the stator winding connections. A 5hp, nine-phase PPMIM drive with the proposed DSPW is designed by using Ansys Maxwell 2-D FEM tool. The power circuit is designed in Simplorer environment (associated tool for Maxwell 2-D) for co-simulating the Maxwell model of PPMIM drive. Moreover, the torque ripple percentage of PPMIM drive for both concentrated winding as well as for distributed winding has been compared. The proposed drive will offer the wider range of speed and torques which is best suitable for traction and ship propulsion applications.

For any switching frequency, multilevel inverters produce better harmonic profile compared to basic 2-level inverters. Among the available multilevel inverters topologies in the literature, some of the topologies like neutral point clamped (NPC) or diode clamped, flying capacitor (FC) or capacitor clamped, and H-bridge are conventionally used. However, the NPC and FC type inverter topologies comprises the capacitor voltage balancing issue, and the H-bridge requires more number of isolated DC voltage sources and semiconductor switches. To overcome the issues encountered with the conventional topologies, a new single-phase 5-level inverter topology by excluding the capacitor components and with a reduced number of semiconductor switches is proposed in this paper. A reduced number of levels is also achieved with the proposed topology under certain fault conditions.

The interest on Multiphase induction motor drives with pole-phase modulation is intensifying in traction, ship propulsion and electrical vehicles applications due to their potential benefits over the three phase induction motor drives. However, in PPM the number of poles and phase are varied in a perpetual manner for attaining the wider speed and torque characteristics. For meeting the high torque requirement of these applications poles has to be increased in PPM. This increment in number of poles leads to higher magnitude of space harmonics in airgap that intensifies the torque pulsations. To address this, carrier phase shifted SVPWM (CPS-SVPWM) is proposed in this paper. For supplying the multilevel voltage across effective phase the carriers of equal voltage profile windings are displaced by an angle of 120°. This CPS-SVPWM cancels the lower center band harmonics and the remaining side bands are shifted to 6 times of the carrier frequency. In this way, the time harmonics in the airgap are reduced by supplying the multilevel voltage. The aim is to give an optimal phase shift angle between the carriers to get the better performance of the PPMIM drive. Moreover, the dc-link voltage utilization (DL VU) is improved by the 15.4 % in both pole- phase combinations with phase groping concept. The performance of the PPMIM drive with 60° and 120° CPS-SVPWMs are compared w.r.t their pros and cons. The proposed 120° CPS-SVPWM concept is executed with Maxwell 2-D finite analysis (FEM analysis) by implementing a 5hp PPMIM FEM model. Further the efficacy of this concept is validated by using laboratory porotype of 9-phase 5hp PPMIM drive. The PPMIM drive is controlled with SPARTAN-6 FPGA board, where the switching algorithm is written using VHDL.

In modern residential applications, the dc based power systems are being increasingly implemented for smart and green energy efficient operation. The power requirement for these residential applications can be fulfilled by small localized generation (i.e., renewable energy), which can serve different variety of consumer loads. Some of the critical loads in these applications may require galvanic isolation from the input source. This paper proposes a boost multi-port converter with simultaneous isolated dc, non-isolated dc and ac outputs. These non-isolated dc, isolated dc, ac loads and dc source are interfaced using a single power converter topology. The salient features of proposed converter include less device count, number of power conversions and the ability to regulate both the outputs independently using decoupled modified sinusoidal pulse width modulation(DMSPWM) technique. The characteristics of the proposed converter with DMSPWM control have been studied in this paper and simulated using a MATLAB/Simulink. The proposed operation has been verified using FPGA controlled laboratory prototype. And also, the proposed topology is compared with conventional topologies in various aspects.

Actions can be recognized effectively when the various atomic attributes forming the action are identified and combined in the form of a representation. In this paper, a low-dimensional representation is extracted from a pool of attributes learned in a universal Gaussian mixture model using factor analysis. However, such a representation cannot adequately discriminate between actions with similar attributes. Hence, we propose to classify such actions by leveraging the corresponding class labels. We train a Siamese deep neural network with a contrastive loss on the low-dimensional representation. We show that Siamese networks allow effective discrimination even between similar actions. The efficacy of the proposed approach is demonstrated on two benchmark action datasets, HMDB51 and MPII Cooking Activities. On both the datasets, the proposed method improves the state-of-the-art performance considerably.

This paper proposes a 3-level inverter scheme with a single dc source to enhance the performance of pole phase modulated multiphase induction motor drives (PPMMIM). Each phase of the traditional 9-0 4-pole induction motor (IM) has two series connected identical voltage profile coils (IVPC) with a span of two pole-pitches. These two IVPC's are disconnected and reconnected as two 9-phase star groups, which are excited with 9-0 2-level inverters separately. But these inverters are connected to the common-dc link. The dc-link requirement of the 9-0 IM drive is reduced by 6 times as compared with the traditional 3-0 IM drive. In high pole operation, PPMMIM drives supplies huge starting torque with reduced phase count, which increases the magnitude space harmonics in air gap. With the help of phase shifted carrier space-vector pulse width modulation (SVPWM) the proposed MLI scheme produces the multilevel voltage across the effective phase. The first center band harmonics in the effective voltage are cancelled because of the 1800 phase shifted references. In addition, the other center band harmonics are moved to the higher order of frequencies due to phase shifted carriers. This improvement in harmonic profile as well as multilevel voltage excitation improves the performance of the PPMMIM drive in 12-pole mode. In low pole mode, the dc-link voltage utilization (DLVU) of the MIM drive is enhanced by 15.4% with the help of third harmonic injected SVPWM. A 5hp 9-0 4-pole FEM model is designed in Ansys Maxwell 2-D for validating the proposed MLI configuration. This configuration is also verified by using laboratory prototype.

A split source boost switched capacitor multi-level inverter (SBSCMI) is proposed in this paper for low power applications. The SBSCMI is derived from the flying capacitor multi-level inverter and switched capacitor structure for achieving step-up dc-ac conversion. With these special composite structure, the no. of devices in the proposed SBSCMI are less as compared to conventional multilevel inverter. In this topology few switches are operated under line voltage frequency, results in reduction of switching losses. Because of switched capacitor operation, SBSCMI provides a voltage gain of 1.5 time to input voltage with a reduced switching voltage stress. The modified phase opposition and disposition sinusoidal pulse width modulation method is used as a control strategy for SBSCMI. With this control, the capacitor voltages are self-balanced and quality of output waveforms are improved significantly. The proposed SBSCMI is validated using MATLAB/simulink and the effectiveness of this topology is compared with existing topologies in aspects of power quality, device count, size of passive elements, voltage gain, switching stress and power losses.

Multiphase induction motor (MIM) drives are becoming popular for high-power applications because of fault tolerant capability and wide range speed-torque characteristics. Using pole-phase modulation (PPM) technique, it is able to give high-torque for faster acceleration as well as high speed during steady operation. To achieve both these features, the MIM drive requires higher number of stator slots that may increase size and weight of the drive. However, these two major constraints limit the pole phase modulated MIM (PPMMIM) drives for medium and low power applications. To address these issues, in this paper a fractional-slot multilayer winding (FSMLW) for PPMMIM drive is proposed for getting multi-speed ratios with the conventional 36 slots stator core frame. This FSMLW improves the harmonic profile in the air gap magneto-motive force (MMF) and efficiency of the PPMMIM drive. In addition, generalization of the PPM is revised by considering number of layers per slot. The proposed MIM drive operates in 15-phase 2-pole mode, 5-phase 6-pole mode and 3-phase 10-pole modes by using PPM. With these three pole-phase combinations, the drive is capable to runs at 1:3:5 speed ratios. The proposed 36-slot PPMMIM drive facilitates wider range of speed-torque characteristics with FSMLW. This can make it suitable for medium and low power applications. The effectiveness of the proposed MIM drive with FSMLW is verified by using FEM analysis using ANSYS Maxwell-2D. A two-level inverter is designed in Simplorer environment for co-simulating the proposed MIM drive.

Representation and modelling of movements play a significant role in recognising actions in unconstrained videos. However, explicit segmentation and labelling of movements are non-trivial because of the variability associated with actors, camera viewpoints, duration etc. Therefore, we propose to train a GMM with a large number of components termed as a universal movement model (UMM). This UMM is trained using motion boundary histograms (MBH) which capture the motion trajectories associated with the movements across all possible actions. For a particular action video, the MAP adapted mean vectors of the UMM are concatenated to form a fixed dimensional representation referred to as “super movement vector” (SMV). However, SMV is still high dimensional and hence, Baum-Welch statistics extracted from the UMM are used to arrive at a compact representation for each action video, which we refer to as an “action-vector”. It is shown that even without the use of class labels, action-vectors provide a more discriminatory representation of action classes translating to a 8 % relative improvement in classification accuracy for action-vectors based on MBH features over naive MBH features on the UCF101 dataset. Furthermore, action-vectors projected with LDA achieve 93% accuracy on the UCF101 dataset which rivals state-of-the-art deep learning techniques.

The dual connectivity (DC) can increase the users' throughput in heterogeneous cellular networks (HCNs). Additionally, the coordinated multi-point (CoMP) based transmission/reception can provide higher coverage and throughput in HCNs, specially to edge users in the cell. In this paper, we frame the resource allocation problem for DC as an optimization problem and present the optimal user scheduling for a time based scheduler. We compare the throughput and coverage performance of DC with respect to CoMP in a HCN. Further, extensive simulation results are presented for various user densities and number of small cells in diverse physical scenarios. The results are highly relevant for selection of appropriate technology in HCNs by cellular network operators.

In hybrid microgrids, integration of multiple renewable energy sources to AC and DC buses of grid require a boost and multi-level inverters. Depending on the requirement, these boost and multi-level converters are connected either in parallel or in cascaded. In this parallel or cascaded arrangement the device count and control complexity increases. And, also it requires a separate AC and DC output control (for modulation index and duty ratio). So, these arrangement cannot give the fully controlled simultaneous DC and AC outputs. With this intent, this paper proposes a simplified converter with simultaneous AC and DC outputs. This proposed converter topology is derived by modifying the DC-DC boost converter power switch with a multi-level inverter. This resulting simplified topology requires less number of devices (switches) to produces a simultaneous boost DC and multi-level AC waveforms with a shoot through protection for a multi-level converter. A suitable pulse width modulation (PWM) control strategy is described and simulation results are presented using MATLAB/Simulink. And also, the mathematical analysis of the proposed converter has been derived and compared with conventional/already existing designs.

Generally, in MVDC shipboard micogrid system, all the loads, and sources are connected to centralized MVDC bus through suitable power electronic converters. These power electronic converters are of two port structure and are used to control the parameters of MVDC bus, source, and load. If any fault occurs on source/sink connection or MVDC bus, results in the isolation of source/sink from the MVDC bus or total shutdown of the MVDC system. This decreases the performance of the shipboard sub-systems. For providing the uninterrupted power supply problem during faults, this paper presents a new fault tolerant two layer shipboard microgrid architecture for next generation electric ships. This two layered microgrid architecture has one MVDC bus and one MVAC bus, which are connected through interlinking converter. And, all the electrical equipment (sources/sinks) are connected to both MVDC/MVAC buses through a three port converter (TPC). In normal operation of TPC, sources/sinks are connected to its respective bus. And, if any fault will occur on any of the buses, TPC shifts its source/sink of the faulted bus to un-faulted bus. The fault tolerant two layer microgrid system was simulated using MATLAB/Simulink. The comparative results shows the effectiveness of the proposed architecture.

AC and DC sub-grids in a hybrid microgrid are connected through interlinking AC-DC bi-directional converter. The storage was connected to either of the AC or DC sub-grids. Because of storage system integration, it requires a more number of power conversions and device count. So, power quality and overall efficiency of the hybrid microgrid system is decrease. On this intend, this paper proposes a new non isolated single stage three port converter (NISSTPC) for microgrid applications. NISSTPC has three bi-directional ports, which are connected to AC and DC sub grids, storage system. Single stage power conversion is possible either side using NISSTPC. Because of this single stage power conversion of NISSTPC the power quality and conversion efficiency of hybrid microgrid system is increase. The validation of proposed NISSTPC using MATLAB/Simulink and results are compared with conventional hybrid microgrids in aspects of power quality, frequency deviation and utilization of storage. From the results, it can be observed that the overall performance of the hybrid microgrid increases with the use of proposed NISSTPC converter

In hybrid microgrids, integration of the low voltage renewable energy sources to high voltage AC and DC buses of grid requires a multiple voltage conversions. These conversions include low voltage to medium voltage and medium voltage to high voltage. When the number of conversions are increased the device count increases and power quality decreases. With this intent, this paper proposes a DC-AC/DC Three Port High Step-up Multi-level Converter (TPHSMC) topology. It has one input and two output ports namely low voltage DC input port, high voltage AC and high voltage DC output ports. The converter is a combination of switched capacitor with single DC source arrangement ( for producing multilevel boost output DC levels using single input DC source), auxiliary switches and H-bridge inverter. Operation of the converter topology is explained with the help of a single DC source nine-level high step-up three port converter. An appropriate control scheme is described and simulation results are presented using MATLB/Simulink. The proposed TPHSMC topology compared with existing topologies in aspects of power quality, device count, size of passive elements, boosting and three-port capabilities are presented to illustrate the effectiveness of the proposed converter.

Recent developments in hybrid microgrid systems have brought challenges to the development of new power conversion circuits, which integrate multiple input and output. In traditional hybrid microgrid, interlinking converter integrate AC and DC buses but, it cannot integrate storage system. It require more power conversions, device count to transfer power from one side to other side. It reduces power quality and overall efficiency of the system. The recent development in new power conversion circuit, can integrates multiple input and output. The use of these multi-port power converters in hybrid microgrids are integrating different DC source to centralized DC bus. These existing multi-port converts do not fulfill the requirement of DC-DC/AC power conversion to interface storage system with AC and DC buses. On this basis, this paper proposes a new isolated three port converter (ITPC) having storage port, DC microgrid port and AC microgrid port. It improves the performance of hybrid microgrid with all kinds of power conversions like AC/DC-AC, AC-AC/DC, DC-AC/DC, and AC/DC-DC. This ITPC tested with hybrid microgrid using MATLAB/Simulink® and comparative results with traditional microgrid architectures are presented in the aspects of power transfer capability, energy management of the storage system, and power quality of the microgrid system.

Feature descriptors involved in video processing are generally high dimensional in nature. Even though the extracted features are high dimensional, many a times the task at hand depends only on a small subset of these features. For example, if two actions like running and walking have to be identified, extracting features related to the leg movement of the person is enough. Since, this subset is not known apriori, we tend to use all the features, irrespective of the complexity of the task at hand. Selecting task-aware features may not only improve the efficiency but also the accuracy of the system. In this work, we propose a supervised approach for task-aware selection of features using Deep Neural Networks (DNN) in the context of action recognition. The activation potentials contributed by each of the individual input dimensions at the first hidden layer are used for selecting the most appropriate features. The selected features are found to give better classification performance than the original high-dimensional features. It is also shown that the classification performance of the proposed feature selection technique is superior to the low-dimensional representation obtained by principal component analysis (PCA).

We consider the special case of index coding over the Gaussian broadcast channel where each receiver has prior knowledge of a subset of messages at the transmitter and demands all the messages from the source. We propose a concatenated coding scheme for this problem, using an index code for the Gaussian channel as an inner code/modulation to exploit side information at the receivers, and an outer code to attain coding gain against the channel noise. We derive the capacity region of this scheme by viewing the resulting channel as a multiple-access channel with many receivers, and relate it to the side information gain - which is a measure of the advantage of a code in utilizing receiver side information - of the inner index code/modulation. We demonstrate the utility of the proposed architecture by simulating the performance of an index code/modulation concatenated with an off-the-shelf convolutional code through bit-interleaved coded-modulation.

The index coding problem involves a sender with K messages to be transmitted across a broadcast channel, and a set of receivers each of which demands a subset of the K messages while having prior knowledge of a different subset as side information. We consider the specific instance of noisy index coding where the broadcast channel is Gaussian and every receiver demands all the messages from the source. We construct lattice index codes for this channel by encoding the K messages individually using K modulo lattice constellations and transmitting their sum modulo a shaping lattice. We introduce a design metric called side information gain that measures the advantage of a code in utilizing the side information at the receivers, and hence its quality as an index code. Based on the Chinese remainder theorem, we then construct lattice index codes for the Gaussian broadcast channel. Among all lattice index codes constructed using any densest lattice of a given dimension, our codes achieve the maximum side information gain.

In hyperconnectivity scenario, managing the amount of data acquired from sensors in the Body Area Networks (BANs) is one of the major issues. In this paper we propose an on-chip context predictor based sparse sensing technology with smart transmission architecture which makes use of confidence interval calculation from the features that present in the data, thereby achieving statistical guarantee. The proposed architecture uses intelligent sparse sensing, which eradicates the collection of redundant data, thereby reducing the amount of data generated. For the performance analysis, we considered ECG data acquisition and transmission system. The proposed architecture when applied on the data collected from 10 patients reduces the duty cycle of the sensing unit to 27.99%, by achieving an energy saving of 72% and the mean deviation of sampled data from the original data is 2%.

This paper presents an epoch extraction method from the phase spectrum of speech signals. The phase spectrum of speech is modelled as the response of an allpass (AP) system. The coefficients of AP system are estimated by imposing sparsity constraint on the input signal. The AP residual is estimated using orthogonal matching pursuit and it is found that the residual signal exhibits prominent peaks at epoch locations and negligible values elsewhere. A dynamic programming algorithm is employed to select appropriate peaks from AP residual corresponding to epoch locations. Epoch extraction performance of the proposed algorithm is evaluated on a subset of CMU Arctic database. The AP modelling based epoch extraction method is compared with two state-of-the-art epoch identification techniques, namely DYPSA and zero frequency resonator (ZFR). It is observed that the proposed algorithm delivers equivalent performance as that of ZFR for clean speech and significantly out-performs ZFR for telephone speech. Also the AP modelling based method provided slightly better epoch identification rate than DYPSA for clean as well as telephone speech.

Significant expansion of PV-grid installations have escalated new problems of PV penetration because of intermittent nature of the PV source and inertia-less interface. In this paper, a novel active and reactive power control scheme for a single stage PV-grid system is proposed to counter the potential PV penetration problems for the futuristic grid with large distributed generation system (DGS) contributions. The proposed work incorporates a PV power control algorithm, which not only facilitates maximum power point tracking (MPPT) but also provides precise PV power control, unlike conventional MPPT schemes. These features significantly overcome power and voltage fluctuations, reverse power flow problems and overvoltage issues, which are considered as major potential PV penetration problems and the main reason for limiting large PV installations. In addition, the reactive power control ability increases the effectiveness of the proposed scheme for feeder voltage profile improvement and utilization of the interfacing power converter. A 3-Ph, single stage PV-grid system is considered with the PV source directly integrated with the DC link of the inverter. The DC link voltage is controlled by the inverter. Detailed analysis, modeling and control design are included and supported by key simulation and experimental results.

Applications based on renewable energy sources are getting worldwide attention. Laboratory level research involving renewable energy sources, poses many difficulties like high cost, dependency on environmental conditions and its repeatability, space requirements etc. These difficulties can be sorted out by using a hardware emulator that can accurately mimic the characteristics of a particular renewable energy sources. An emulator is supposed to replicate the voltage and current (V–I) steady state and dynamic characteristics of any source such as solar Photovoltaics (PV), Fuel Cell (FC) etc. Typically it is a low cost and a portable alternative for the use of actual renewable sources. Unfortunately, many of them suffer from poor dynamic response as compared to their actual counterparts. This paper proposes a new integrated emulator that provides emulation with fast load tracking capability for three energy sources viz. solar PV, Proton Exchange Membrane fuel cell (PEMFC) and battery. This can offer a low cost solution for test-bed setup facilitating the continuous research efforts irrespective of the actual environmental conditions in the field of renewable energy and NCE. The proposed emulator is designed and built around a Texas Instrument's TMS320F28027 controlled flyback converter and National Instrument's NIDAQ USB6008 interfaced with LabVIEW based GUI. Key results of the proposed system along with control implementation and modeling are presented.

Recently hierarchical control of microgrid has been the focus of extensive research due to its flexibility to effectively utilize the micro-sources while ensuring reliability. The work presented in this paper is focused on the design and development of a photovoltaic (PV) power conditioning system for a hierarchically controlled microgrid application. The PV interface is equipped with multiple functionalities such as droop characteristic control for both active and reactive power sharing, centralized power sharing, adaptive power control etc. All these features make the PV interface one of the main power contributing sources. A detailed control design procedure for this microgrid PV source is given. The effectiveness of the proposed control scheme is investigated with a laboratory prototype of the microgrid with hierarchical control supported by sources like Solar PV, Wind, hydro turbine driven synchronous machine and Fuel cell based renewable energy sources. The microgrid has the capability of reconfigurable control. The Local Source Controllers (LSC) are linked with Controller Area Network (CAN) for fast data transfer and RS-485 for bulk data transfer. Battery storage is provided for prolonged energy back up and ultracapacitor for transient and momentary power support during dynamic phase. The PV interface of this microgrid is investigated under various conditions such as large variation in its radiation level, maximum power point tracking, centralized control for active power, co-ordinate active and reactive power control with de-centralized operation, hierarchical control functionality of PV source with other microgrid sources etc. The intermittent nature of photovoltaic source causes a peculiar impact on the microgrid operation. This and other important observations are analyzed for further study and investigations into the control aspects of PV sources in a microgrid paradigm. The key simulation and experimental results are included to verify proper operation and control of the microgrid.

An algorithm to estimate allpass transfer functions by assuming sparsity over the input signals is proposed in this paper. As a tractable measure of sparsity, the l 1 norm of input signal is minimized and the set of allpass coefficients which realizes the l 1 norm minimization is obtained. It is observed that the estimation of allpass systems with sparse inputs is a nonconvex problem and hence a nonconvex optimization method-the particle swarm optimization (PSO) is used. With PSO, a large number of uniformly chosen points in a d-dimensional problem space are guided towards an optimum solution with respect to the l 1 norm of input signal. Experimental results show that PSO is successful in estimating allpass transfer functions. Application of allpass filter estimation to speech processing is also studied and results which portray the effectiveness of the proposed method are reported.

The objective of this work is to study the suitability of existing spectral mapping methods for enhancement of throat microphone (TM) speech, and propose a more elegant method for spectral mapping. Gaussian mixture models (GMM) and neural networks (NN) have been used for spectral mapping. Though GMM-based mapping captures the variability among speech sounds through multiple mixtures, it can only provide a linear map between the source and the target. On the other hand, NN-based mapping is capable of providing a nonlinear map but a single mapping scheme may not handle variability across different speech sounds. Incorporating the advantages from these approaches, we propose a spectral mapping method using multiple neural networks. Speech data is clustered using k-means algorithm, and a separate neural network is employed to capture the mapping within each cluster. Objective evaluation has shown that proposed method is better than both GMM-base and NN-base mapping schemes.

Substantial growth in the solar photovoltaic utilization and high PV penetration demands new and more flexible PV power control algorithms. In this paper, a modified control algorithm is proposed for PV based systems which control power yield from the PV installation. The conventional maximum power point tracking (MPPT) algorithms are in extensive use for optimized power yield. Unfortunately, they don't provide any flexibility in the control of other electrical parameters. The proposed algorithm allows MPPT and also provides additional flexibility of power control which is today's need to develop more sophisticated PV based systems. The proposed control algorithm can be easily embedded in most PV applications, to achieve power control functionality. This is possible without hampering the basic MPPT functionality. The detailed modeling of PV-fed converter is presented. The new approach of converter control design and control scheme have also been discussed. Simulation results are provided to evaluate the designed controllers and working of the proposed algorithm.

This paper describes the multi-level reconfigurable hierarchical control of a laboratory prototype Microgrid comprising Photovoltaic (PV), wind turbine, micro-hydro and fuel cell based renewable energy sources. The transient and momentary power back up is incorporated through ultra-capacitor. Prolong power back-up is provided with battery energy storage. The major part of power is generated by renewable energy sources, which produce raw power under varying weather conditions. This may cause disruptive effects such as voltage fluctuations, voltage dips, frequency variation and harmonic distortion on the grid if not properly controlled and coordinated. Issues like intermittent nature of PV and wind sources, significantly different dynamic behavior of various sources and dissimilar generating capacities of sources have an adverse effect on the microgrid operation. For achieving an optimum and reliable performance of the microgrid, a hierarchical control is both necessary and critical. This paper presents a four level “re-configurable” hierarchical control scheme for the microgrid. A notable feature of the proposed architecture is the capability of the resource manager layer to transfer its functionalities to the global microgrid control layer (or vice versa) in the event of emergency. Various aspects related to this kind of microgrid control with relevant analytical and experimental details are presented.

In a conventional grid connection of Photovoltaic (PV) system, a number of PV modules are connected in series and integrated to grid through a conventional two level inverter. Due to the impact of partial shading and module mismatch, such systems have a much lower yield compared to their maximum potential. To address this problem, direct connection of PV source to a three-level diode clamped inverter is considered in this paper, resulting in a single stage power conversion. A novel auxiliary converter is proposed that allows the two split halves of the PV source to be directly connected to the two dc-link capacitors, with each half operating at it's respective Maximum Power Point (MPP). This auxiliary converter can be rated for less power converter compare to the inverter capacity. The unequal MPP voltage of these split PV panels may cause detrimental effect on output current of inverter. To address this power quality issue, a modified switching algorithm is discussed to achieve voltage equalization across the split DC-Links of the multilevel inverter. Though the case of a split PV source (with two halves) has been considered, the proposed scheme is equally valid for a PV array split into more than two parts that may be suitable for a higher level Neutral Point Clamped (NPC) inverter. The proposed auxiliary converter and algorithm are evaluated and verified by simulation in MATLAB-Simulink.

Interfacing inertia-less large PV sources to the power system raises complex PV penetration issues such as bus voltage fluctuation, active power variation, reactive power flow and sharing, system instability etc. This paper proposes a new control technique for large capacity centralized PV fed grid connected systems which enhances the system stability by damping out the low frequency power swing. The presented work addresses a major PV penetration issue - that of system instability, by proposing a modified control scheme of the power conditioning unit of a PV source. The proposed scheme improves the small signal stability and dynamic security of the system without introducing any additional devices (e.g. PSS). The developed analytical approach for the control law is based on the structure preserving energy function (SPEF) model. In order to evaluate the proposed controller and validate the control law, a conventional model of the two machine system with double line transmission is interfaced with a large PV source of rating comparable to that of conventional generator capacities. A notable feature of this work is that the derived control law uses only the locally measurable signals and is independent of the location of the PV source in the system. Further, it does not affect the MPPT control of the PV system in any manner.

The intermittent but complimentary nature of solar photovoltaic and wind mill generated power explored a new area of research for the hybrid PV/wind systems. This paper proposes a novel strategy for the control of power conditioning units to minimize the disturbances on the output power from the hybrid system, integrated with PV and wind turbine, in spite of highly intermittent nature of these sources. The proposed scheme balances the wide variation of power yield from wind and/or PV system and provides sufficient margin to the other sources (e.g. hydro, steam turbine, etc.) connected to the system to take over, so that to maintain power balance throughout the operation. The presented strategy makes use of high energy density ultracapacitor to absorb the effect of intermittent solar radiation and widely varying wind velocity. The MPPT associated with these sources remains unaffected and does not hamper overall generation from the system. The DC link of the conventional back to back topology of the wind farm is integrated with the PV panels with their MPPT trackers. The control strategy uses an inner fast current control loop and an outer slow voltage correcting loop for both the grid side VSI and the ultracapacitor converter. Simulation results are presented in the support of effectiveness of the proposed technique. A prototype is developed with the available 1.5kW PV installation, 1.2kW emulated wind turbine and ultracapacitor bank to validate some aspect of the proposed strategy.

This paper proposes a novel control scheme to minimize the disturbance on the PV fed distributed generation system output power in spite of a wide variation in the solar radiation level. The proposed scheme makes use of high energy density ultracapacitor to absorb the effect of intermittent solar radiation. In the event of a sudden fall in the PV power, the presented scheme provides sufficient margin to the other sources (e.g. hydro, steam turbine, etc.) connected to the system to take over. A notable feature of this scheme is that it does not disturb the MPPT of the trackers associated with the PV panels. The control strategy uses an inner fast current control loop and an outer slow voltage control loop for both voltage source inverter and ultracapacitor converter. The loops are designed using the small signal modeling of the system. Simulation results are presented in support of the effectiveness of the proposed technique. A prototype is developed with the available 2kW PV installation and ultracapacitor bank. Hardware results are included to validate the analysis and simulation results of the proposed control strategy.

This paper proposes a novel control technique for a large centralized PV-grid generating station to incorporate the attributes of AVR and governor and to make it perform like conventional steam and hydro turbine generators. The objective is to be able to interface and integrate large PV generators with the power grid in a “seamless” manner. The PV power capacity is considered comparable to any of the existing, large generator capacity with a typical load cycle. The proposed control strategy allows precise active power control with the set dynamics of frequency droop characteristic akin to the action of governor in conventional generators, to share the load and to control the bus frequency under certain conditions. The control also has the feature of sharing maximum capacity under normal operation working with MPPT scheme. The proposed control strategy also realizes the AVR action of conventional generators, so as to regulate the bus terminal voltage by reactive power control. Complete system modeling and analytical approach is presented to design the compensator and tune the PI regulators of the current control loops. Simulation results are presented for the system under study, showing the efficacy of the proposed control strategy. The system is designed in hardware to validate certain aspects of the simulation results.

This paper proposes the essential operating modes and control scheme for large capacity, centralized PV-grid systems to overcome the penetration issues. The injected PV power is considered comparable to the existing feeder capacity with typical loads on the line. Various control techniques are proposed to achieve full flexibility of operating mode selection by the operator/Load Dispatch Center (LDC) to overcome major PV penetration problems of active power sharing, voltage fluctuation, reactive power support and system instability. A major outcome of this work is that it empowers the operator to deal with these complex PV penetration issues by facilitating precise active power control, reactive power control, AC bus voltage regulation, active power sharing and economical load dispatching. New control philosophy for the boost converter and the voltage source inverter (VSI), which constitute the conventional PV-grid interface, is proposed under different operating modes. Major and essential modifications in the conventional power and control circuits and need for additional bi-directional control signals are highlighted and incorporated. These advance control features allow the utility to interface huge capacity PV plants with the power grid and reduce the burden on conventional power plants, without causing system malfunction on account of voltage variation, impact of passing clouds, reactive power demand, intermittent active power, etc. A linearized small-signal model of the PV-grid system is derived to design the controller of the boost converter and tuning the PI regulator of the VSI. Simulation results for critical conditions are presented showing the effectiveness of the proposed control scheme under various operating modes.

This paper proposes a cost effective, compact and precise photovoltaic emulator. It is able to emulate accurately the current-voltage characteristics of a PV source for varying temperature and solar radiation. The proposed system also has the ability to emulate the re-configuration of the PV panels for series and parallel connection. The emulator is developed with a galvanically isolated power electronic topology with high frequency transformer, to achieve a light weight and compact system for easy handling. The proposed system has features of online set point variation of insolation and temperature. Standard module of V oc =21 volts and I sc =2 Amp at 1000w/m2 is chosen as a base selection and panels with desired configuration can be formed by appropriate selection of the series and parallel bits provided on the front of unit for the purpose. The unit can provide up to 150W of power. Detailed design is provided for the flyback converter used as the basic power electronic topology at the heart of the emulator. The control of the output voltage and current is achieved using a types-3 compensator, designed using K factor approach to achieve good dynamic response. The controller and the monitoring panel are implemented using a ‘low end’ dsPIC microcontroller. All the hardware details of the developed prototype are presented. Experimental results are shown for several cases of panels connected in series and/or parallel for different radiation levels. It is observed that the weight of this 150W unit is about 1 kg, including casing and auxiliary components.

This paper addresses the problem of data compression with local decoding and local update. A compression scheme has worst-case local decoding d wc if any bit of the raw file can be recovered by probing at most d wc bits of the compressed sequence, and has update efficiency of u wc if a single bit of the raw file can be updated by modifying at most u wc bits of the compressed sequence. This article provides an entropy-achieving compression scheme for memoryless sources that simultaneously achieves O (log log n) local decoding and update efficiency. Key to this achievability result is a novel succinct data structure for sparse sequences which allows efficient local decoding and local update.Under general assumptions on the local decoder and update algorithms, a converse result shows that the maximum of d wc and u wc must grow as Ω(log log n).