This multilevel inverter methodology is the center of focus among researchers in recent era.It has been focused due to its advantages over existing topologies,drawbacks and improvement of power quality,Multi-level inv...This multilevel inverter methodology is the center of focus among researchers in recent era.It has been focused due to its advantages over existing topologies,drawbacks and improvement of power quality,Multi-level inverter has the ability to generate nearly sinusoidal waves.This sinusoidal wave can be further improved by increasing the level of output voltage or with the help of filter design,and this manuscript presents single-phase Multi cell Multi-Level Inverter(MLI).It has been considered for reducing component count to get a higher number of output voltage levels and lower Total harmonics distortion profile.It comprises with four symmetric DC input voltage and 10 IGBT switches to produces stepped output of 9 level,and when deploy asymmetric Dc voltage source the same circuit will produce 31 level output with some changes in firing scheme,moreover this circuit is the family of cascaded hybrid bridge inverter so this circuit covered advantage of CHB MLI,This circuit uses lower no.of switch as compared to existing conventional MLIs such as FC-MLI,CHB-MLI,NPC-MLI,This paper also provides one of most pertinent controls and modulation mechanisms for a MLI using a hybrid reference/carrier-oriented sinusoidal PWM mechanism.At last,simulated outcomes are to validate the performance of both architectures in MLI structure as well as verify the concept.展开更多
A correlation-based digital background calibration algorithm for pipelined Analog-to- Digital Converters (ADCs) is presented in this paper. The merit of the calibration algorithm is that the main errors information, w...A correlation-based digital background calibration algorithm for pipelined Analog-to- Digital Converters (ADCs) is presented in this paper. The merit of the calibration algorithm is that the main errors information, which include the capacitor mismatches and residue amplifier distortion, are extracted integrally. A modified 1st pipelined stage is adopted to solve the signal overflow caused by the Pseudo-random Noise (PN) sequences. Behavioral simulation results verify the effectiveness of the algorithm. It improves the Signal-to-Noise-plus-Distortion Ratio (SNDR) and Spurious-Free-Dynamic-Range (SFDR) of the pipelined ADC from 41.8 dB to 78.3 dB and 55.6 dB to 98.6 dB, respectively, which is comparable to the prior arts.展开更多
In recent day’s power distribution system is distress from acute power quality issues.In this work,for compensating Power Quality(PQ)disturbances a seven level cascaded H-bridge inverter is implemented in distributio...In recent day’s power distribution system is distress from acute power quality issues.In this work,for compensating Power Quality(PQ)disturbances a seven level cascaded H-bridge inverter is implemented in distribution static com-pensator which protects power quality problems in currents.Distribution Static Compensator(DSTATCOM)aid to enhances power factor and removes total har-monic distortion which is drawn from non-linear load.The D–Q reference theory based hysteresis current controller is employed to generate reference current for compensation of harmonics and reactive power,additionally Probabilistic Neural Network(PNN)classifier is used which easily separates exact harmonics.In the meantime fuzzy logic controller is also used to maintain capacitor DC-link poten-tial.When comparing to PI controller it decreases steady state time and reduces maximum peak overshoot.Cascaded H-bridge multilevel inverter converts direct current to Alternating current,through inductor opposite harmonics are injected in Power Control Centre reduces source current harmonics and reactive power.The implementation of CHBMLI in distribution STATic COMpensator simulation model is simulated by means of MATLAB.展开更多
In contemporary power grids or microgrids,harmonic distortion has emerged as one of the critical power quality issues for utility power grids,which has escalated especially due to the high penetration of power-electro...In contemporary power grids or microgrids,harmonic distortion has emerged as one of the critical power quality issues for utility power grids,which has escalated especially due to the high penetration of power-electronic-converter-interfaced distributed generation(DG).This paper first illustrates the prevalent dispute revolving around the harmonic power sharing and distortion restraint,and subsequently proposes a consensusbased framework that facilitates an accurate sharing of harmonics among multi-DGs connected in parallel,with an effective suppression of the output voltage distortion.Compared with the majority of existing studies addressing the issue of voltage harmonics at the point of common coupling(PCC),our method primarily emphasizes on the output voltage distortion since the power quality requirement for certain local critical loads is often known to be high.With the help of adaptive regulation,the overall distortion produced at the output terminals of DGs can be retained within an acceptable range.The working principle of the proposed control method,which is not only easy to implement but also independent of model parameters,is further described in detail.Employing the small-signal dynamic model,the system stability and robustness are analyzed.The hardware-in-the-loop(HIL)simulations aid in determining the outcome of the proposed strategy in microgrid control.展开更多
Due to development of distribution systems and increase in electricity demand,the use of capacitor banks increases.From the other point of view,nonlinear loads generate and inject considerable harmonic currents into p...Due to development of distribution systems and increase in electricity demand,the use of capacitor banks increases.From the other point of view,nonlinear loads generate and inject considerable harmonic currents into power system.Under this condition if capacitor banks are not properly selected and placed in the power system,they could amplify and propagate these harmonics and deteriorate power quality to unacceptable levels.With attention of disadvantages of passive filters,such as occurring resonance,nowadays the usage of this type of harmonic compensator is restricted.On the other side,one of parallel multi-function compensating devices which are recently used in distribution system to mitigate voltage sag and harmonic distortion,performs power factor correction,and improves the overall power quality as active power conditioner(APC).Therefore,the utilization of APC in harmonic distorted system can affect and change the optimal location and size of shunt capacitor bank under harmonic distortion condition.This paper presents an optimization algorithm for improvement of power quality using simultaneous optimal placement and sizing of APC and shunt capacitor banks in radial distribution networks in the presence of voltage and current harmonics.The algorithm is based on particle swarm optimization(PSO).The objective function includes the cost of power losses,energy losses and those of the capacitor banks and APCs.展开更多
Power quality challenges have generated a lot of disputes between utilities,customers,network operators,and equipment manufacturers around the world as regards the share of responsibility for power quality solutions,t...Power quality challenges have generated a lot of disputes between utilities,customers,network operators,and equipment manufacturers around the world as regards the share of responsibility for power quality solutions,this results in different levels of financial and technical losses for both the network operators and the customers.One of the major consequences of the operation of heavy-duty factories globally is the corruption of power quality at the point of common coupling(PCC).In order to quantify the harmonics contribution at the PCC by industrial consumers,this paper presents three-phase total harmonics distortion of current(THDi)prediction model at the PCC.The proposed artificial neural network(ANN)models use a multilayer perceptron neural network(MLPN)to predict three-phase total harmonic distortion.The input parameter used in the models is easily measured with basic power meters.The model was trained with input parameters captured at 33 kV and 132 kV voltage levels using power quality meters at five(5)different steel manufacturing plants.Eight(8)different models were designed,trained,validated,and tested with different combinations of input parameters,number of hidden layers,and number of neurons in the hidden layer.The results show that the model with two hidden layers which uses four major power parameters(Current,apparent power,reactive and active power)as input parameters in the training model had the best performance with a 95.5%coefficient of correlation between the measured THDi and the predicted THDi.展开更多
Nonlinear loads in the power distribution system cause non-sinusoidal currents and voltages with harmonic components.Shunt active filters(SAF) with current controlled voltage source inverters(CCVSI) are usually used t...Nonlinear loads in the power distribution system cause non-sinusoidal currents and voltages with harmonic components.Shunt active filters(SAF) with current controlled voltage source inverters(CCVSI) are usually used to obtain balanced and sinusoidal source currents by injecting compensation currents.However,CCVSI with traditional controllers have a limited transient and steady state performance.In this paper,we propose an adaptive dynamic programming(ADP) controller with online learning capability to improve transient response and harmonics.The proposed controller works alongside existing proportional integral(PI) controllers to efficiently track the reference currents in the d-q domain.It can generate adaptive control actions to compensate the PI controller.The proposed system was simulated under different nonlinear(three-phase full wave rectifier) load conditions.The performance of the proposed approach was compared with the traditional approach.We have also included the simulation results without connecting the traditional PI control based power inverter for reference comparison.The online learning based ADP controller not only reduced average total harmonic distortion by 18.41%,but also outperformed traditional PI controllers during transients.展开更多
The method for harmonic cancellation based on artificial neural network (ANN)is proposed. The task is accomplished by generating reference signal with frequency that should beeliminated from the output. The reference ...The method for harmonic cancellation based on artificial neural network (ANN)is proposed. The task is accomplished by generating reference signal with frequency that should beeliminated from the output. The reference input is weighted by the ANN in such a way that it closelymatches the harmonic. The weighted reference signal is added to the fundamental signal such thatthe output harmonic is cancelled leaving the desired signal alone. The weights of ANN are adjustedby output harmonic, which is isolated by a bandpass filter. The above concept is used as a basis forthe development of adaptive harmonic cancellation (AHC) algorithm. Simulation results performedwith a hydraulic system demonstrate the efficiency and validity of the proposed AHC control scheme.展开更多
A complex-valued harmonic functions that are univalent and sense preserving in the unit disk U can be written in the form f = h + g^-, where h and g are analytic in U. We define and investigate a new class SHPλ(α...A complex-valued harmonic functions that are univalent and sense preserving in the unit disk U can be written in the form f = h + g^-, where h and g are analytic in U. We define and investigate a new class SHPλ(α,β)by generalized Salagean operator of harmonic univalent functions. We give sufficient coefficient conditions for normalized harmonic functions in the class SHPλ(α,β) These conditions are also shown to be necessary when the coefficients are negative. This leads to distortion bounds and extreme points.展开更多
Since the dead zone phenomenon occurs in electro-hydraulic servo system, the output of the system corresponding to a sinusoidal input contains higher harmonic besides the fundamental input, which causes harmonic disto...Since the dead zone phenomenon occurs in electro-hydraulic servo system, the output of the system corresponding to a sinusoidal input contains higher harmonic besides the fundamental input, which causes harmonic distortion of the output signal. The method for harmonic cancellation based on adaptive filter is proposed. The task is accomplished by generating reference signals with frequency that should be eliminated from the output. The reference inputs are weighted by the adaptive filter in such a way that it closely matches the harmonic. The output of the adaptive filter is a harmonic replica and is injected to the fundamental signal such that the output harmonic is cancelled leaving the desired signal alone, and the total harmonic distortion (THD) is greatly reduced. The weights of filter are adjusted on-line according to the control error by using least-mean-square (LMS) algorithm. Simulation results performed with a hydraulic system demonstrate the efficiency and validity of the proposed adaptive feed-forward compensator (AFC) control scheme展开更多
A complex-valued harmonic function that is univalent and sense preserving in the unit disk U can be written in the form of f = h + g,where h and g are analytic in U.We define and investigate a new class LH_λ(α,β) b...A complex-valued harmonic function that is univalent and sense preserving in the unit disk U can be written in the form of f = h + g,where h and g are analytic in U.We define and investigate a new class LH_λ(α,β) by generalized Salagean operator of harmonic univalent functions.We give sufficient coefficient conditions for normalized harmonic functions in the class LH_λ(α,β).These conditions are also shown to be necessary when the coefficients are negative.This leads to distortion bounds and extreme points.展开更多
We introduce a new class of complex valued harmonic functions associated with Wright hypergeometric functions which are orientation preserving and univalent in the open unit disc. Further we define, Wright generalized...We introduce a new class of complex valued harmonic functions associated with Wright hypergeometric functions which are orientation preserving and univalent in the open unit disc. Further we define, Wright generalized operator on harmonic function and investigate the coefficient bounds, distortion inequalities and extreme points for this generalized class of functions.展开更多
Like others countries of the world, in Niger also, we are witnessing an increasing use of non-linear electric loads in the domestic, hospital and industrial sectors. However, these loads degrade the shape of the elect...Like others countries of the world, in Niger also, we are witnessing an increasing use of non-linear electric loads in the domestic, hospital and industrial sectors. However, these loads degrade the shape of the electrical signal and cause disastrous effects to the equipment of the distribution system and the devices which are connected to the network. This article highlights the presence of electric harmonics in the distribution network in Niamey city. In order to do this, measurements were taken at the secondary level of the substations using an energy quality analyze r (FLUKE 1735). By using this measuring instrument, we quantified the voltage and current Total Harmonic Distortion (THD) in the three substations. The results obtained show that, although the statutable rates set by the standards are not exceeded for phase conductors, the neutral contains a very critical percentage of distortion on the residential and hospital substations. Moreover, this assessment made it possible to observe the variation of harmonics in the presence of voltage drops.展开更多
The contribution of Renewable Energy Resources(RER)in the process of power generation is significantly high in the recent days since it paves the way for overcoming the issues like serious energy crisis and natural con...The contribution of Renewable Energy Resources(RER)in the process of power generation is significantly high in the recent days since it paves the way for overcoming the issues like serious energy crisis and natural contamination.This paper deals with the renewable energy based micro-grid as it is regarded as the apt solution for integrating the RER with the electrical frameworks.As thefixed droop coefficients in conventional droop control approaches have caused various limitations like low power-sharing and sudden drops of grid voltage in the Direct Current(DC)side,the Harmonized Membership Fuzzy Logic(MFL)droop control is employed in this present study.This proposed droop control for the hybrid PV-wind-battery system with MFL assists in achieving proper power-sharing and minimizing Total Harmonic Distortion(THD)in the emer-gency micro-grid.It eradicates the deviations in voltage and frequency with itsflexible and robust operation.The THD is reduced and attains the value of 3.1%compared to the traditional droop control.The simulation results of harmo-nized MFL droop control are analogized with the conventional approaches to vali-date the performance of the proposed method.In addition,the experimental results provided by the Field Programmable Gate Array(FPGA)based laboratory setup built using a solar photovoltaic(PV)and wind Permanent Magnet Synchro-nous Generator(PMSG)reaffirms the design.展开更多
Due to the operation of power semiconductor switching converters, the content of harmonic currents, which these switching converters take from the feed array, is still increasing. One of the possible ways of minimizin...Due to the operation of power semiconductor switching converters, the content of harmonic currents, which these switching converters take from the feed array, is still increasing. One of the possible ways of minimizing these currents is the use of pulse switching converters. On one hand, the original, characteristic harmonic ones are minimized, but, on the other hand, new frequencies caused by the modulation frequency appear in the current spectrum. The level of the currents of these frequencies is small and is scarcely dependent on the load of the converter. It may happen that the proportional value of the monitored harmonic one is high, although the absolute value is low. In the article presented, there is a description of the activity of the pulse voltage rectifier and an analysis of the current taken. The other part contains the results of the harmonic analysis of the stated current, including both the absolute and proportional values according to the load. In the conclusion, there are results of measurements of pulsed switching converters taken from the real measurement.展开更多
The purpose of this work is to determine the appropriate allocation of a single tuned passive filter “STPF” in a real distribution network at Tala city to prevent harmonic distortion caused by nonlinear loads. This ...The purpose of this work is to determine the appropriate allocation of a single tuned passive filter “STPF” in a real distribution network at Tala city to prevent harmonic distortion caused by nonlinear loads. This design will cover the ideal filter parameter as well as the best filter position. The filter design is based on single and multi-objective functions that optimize the cost of the proposed filters, real power losses, total harmonic distortion “THD,” and individual harmonic distortion “IHD”. Upper and lower limitations for filter parameters, quality factor, voltage and harmonic distortion limits are determined using inequality constraints. This will be done under the equality constraint of power balance. The challenge of optimization is solved using two modern algorithms, jellyfish optimization technique “JFOT” and arithmetic optimization algorithm “AOA”, in which the placements of the filters and their parameters are selected. IEEE 33-bus radial system and an actual system as a part of the Egyptian network at Tala city are used for demonstrating the results obtained by the proposed techniques. The results reveal that the system’s harmonic distortion of current and voltage is reduced less than the limitations of the IEEE 519 standards.展开更多
文摘This multilevel inverter methodology is the center of focus among researchers in recent era.It has been focused due to its advantages over existing topologies,drawbacks and improvement of power quality,Multi-level inverter has the ability to generate nearly sinusoidal waves.This sinusoidal wave can be further improved by increasing the level of output voltage or with the help of filter design,and this manuscript presents single-phase Multi cell Multi-Level Inverter(MLI).It has been considered for reducing component count to get a higher number of output voltage levels and lower Total harmonics distortion profile.It comprises with four symmetric DC input voltage and 10 IGBT switches to produces stepped output of 9 level,and when deploy asymmetric Dc voltage source the same circuit will produce 31 level output with some changes in firing scheme,moreover this circuit is the family of cascaded hybrid bridge inverter so this circuit covered advantage of CHB MLI,This circuit uses lower no.of switch as compared to existing conventional MLIs such as FC-MLI,CHB-MLI,NPC-MLI,This paper also provides one of most pertinent controls and modulation mechanisms for a MLI using a hybrid reference/carrier-oriented sinusoidal PWM mechanism.At last,simulated outcomes are to validate the performance of both architectures in MLI structure as well as verify the concept.
基金Supported by the Doctoral Program Foundation of Institutions of Higher Education of China (No.20120111120008)State Key Lab of ASIC & System(Fudan University) (No. 11KF001)Special Fund for Doctoral Program (Hefei University of Technology) (No.2011HGBZ0953)
文摘A correlation-based digital background calibration algorithm for pipelined Analog-to- Digital Converters (ADCs) is presented in this paper. The merit of the calibration algorithm is that the main errors information, which include the capacitor mismatches and residue amplifier distortion, are extracted integrally. A modified 1st pipelined stage is adopted to solve the signal overflow caused by the Pseudo-random Noise (PN) sequences. Behavioral simulation results verify the effectiveness of the algorithm. It improves the Signal-to-Noise-plus-Distortion Ratio (SNDR) and Spurious-Free-Dynamic-Range (SFDR) of the pipelined ADC from 41.8 dB to 78.3 dB and 55.6 dB to 98.6 dB, respectively, which is comparable to the prior arts.
文摘In recent day’s power distribution system is distress from acute power quality issues.In this work,for compensating Power Quality(PQ)disturbances a seven level cascaded H-bridge inverter is implemented in distribution static com-pensator which protects power quality problems in currents.Distribution Static Compensator(DSTATCOM)aid to enhances power factor and removes total har-monic distortion which is drawn from non-linear load.The D–Q reference theory based hysteresis current controller is employed to generate reference current for compensation of harmonics and reactive power,additionally Probabilistic Neural Network(PNN)classifier is used which easily separates exact harmonics.In the meantime fuzzy logic controller is also used to maintain capacitor DC-link poten-tial.When comparing to PI controller it decreases steady state time and reduces maximum peak overshoot.Cascaded H-bridge multilevel inverter converts direct current to Alternating current,through inductor opposite harmonics are injected in Power Control Centre reduces source current harmonics and reactive power.The implementation of CHBMLI in distribution STATic COMpensator simulation model is simulated by means of MATLAB.
基金supported by the National Science Foundation of China under Grant 52007031the National Science Foundation of Jiangsu Province under Grant BK20200404,the“Zhishan”Yong Scholars Programs of Southeast University,and the Project Funding for Jiangsu Provincial Key Laboratory of Smart Grid Technology and Equipment,Southeast University.
文摘In contemporary power grids or microgrids,harmonic distortion has emerged as one of the critical power quality issues for utility power grids,which has escalated especially due to the high penetration of power-electronic-converter-interfaced distributed generation(DG).This paper first illustrates the prevalent dispute revolving around the harmonic power sharing and distortion restraint,and subsequently proposes a consensusbased framework that facilitates an accurate sharing of harmonics among multi-DGs connected in parallel,with an effective suppression of the output voltage distortion.Compared with the majority of existing studies addressing the issue of voltage harmonics at the point of common coupling(PCC),our method primarily emphasizes on the output voltage distortion since the power quality requirement for certain local critical loads is often known to be high.With the help of adaptive regulation,the overall distortion produced at the output terminals of DGs can be retained within an acceptable range.The working principle of the proposed control method,which is not only easy to implement but also independent of model parameters,is further described in detail.Employing the small-signal dynamic model,the system stability and robustness are analyzed.The hardware-in-the-loop(HIL)simulations aid in determining the outcome of the proposed strategy in microgrid control.
文摘Due to development of distribution systems and increase in electricity demand,the use of capacitor banks increases.From the other point of view,nonlinear loads generate and inject considerable harmonic currents into power system.Under this condition if capacitor banks are not properly selected and placed in the power system,they could amplify and propagate these harmonics and deteriorate power quality to unacceptable levels.With attention of disadvantages of passive filters,such as occurring resonance,nowadays the usage of this type of harmonic compensator is restricted.On the other side,one of parallel multi-function compensating devices which are recently used in distribution system to mitigate voltage sag and harmonic distortion,performs power factor correction,and improves the overall power quality as active power conditioner(APC).Therefore,the utilization of APC in harmonic distorted system can affect and change the optimal location and size of shunt capacitor bank under harmonic distortion condition.This paper presents an optimization algorithm for improvement of power quality using simultaneous optimal placement and sizing of APC and shunt capacitor banks in radial distribution networks in the presence of voltage and current harmonics.The algorithm is based on particle swarm optimization(PSO).The objective function includes the cost of power losses,energy losses and those of the capacitor banks and APCs.
文摘Power quality challenges have generated a lot of disputes between utilities,customers,network operators,and equipment manufacturers around the world as regards the share of responsibility for power quality solutions,this results in different levels of financial and technical losses for both the network operators and the customers.One of the major consequences of the operation of heavy-duty factories globally is the corruption of power quality at the point of common coupling(PCC).In order to quantify the harmonics contribution at the PCC by industrial consumers,this paper presents three-phase total harmonics distortion of current(THDi)prediction model at the PCC.The proposed artificial neural network(ANN)models use a multilayer perceptron neural network(MLPN)to predict three-phase total harmonic distortion.The input parameter used in the models is easily measured with basic power meters.The model was trained with input parameters captured at 33 kV and 132 kV voltage levels using power quality meters at five(5)different steel manufacturing plants.Eight(8)different models were designed,trained,validated,and tested with different combinations of input parameters,number of hidden layers,and number of neurons in the hidden layer.The results show that the model with two hidden layers which uses four major power parameters(Current,apparent power,reactive and active power)as input parameters in the training model had the best performance with a 95.5%coefficient of correlation between the measured THDi and the predicted THDi.
文摘Nonlinear loads in the power distribution system cause non-sinusoidal currents and voltages with harmonic components.Shunt active filters(SAF) with current controlled voltage source inverters(CCVSI) are usually used to obtain balanced and sinusoidal source currents by injecting compensation currents.However,CCVSI with traditional controllers have a limited transient and steady state performance.In this paper,we propose an adaptive dynamic programming(ADP) controller with online learning capability to improve transient response and harmonics.The proposed controller works alongside existing proportional integral(PI) controllers to efficiently track the reference currents in the d-q domain.It can generate adaptive control actions to compensate the PI controller.The proposed system was simulated under different nonlinear(three-phase full wave rectifier) load conditions.The performance of the proposed approach was compared with the traditional approach.We have also included the simulation results without connecting the traditional PI control based power inverter for reference comparison.The online learning based ADP controller not only reduced average total harmonic distortion by 18.41%,but also outperformed traditional PI controllers during transients.
文摘The method for harmonic cancellation based on artificial neural network (ANN)is proposed. The task is accomplished by generating reference signal with frequency that should beeliminated from the output. The reference input is weighted by the ANN in such a way that it closelymatches the harmonic. The weighted reference signal is added to the fundamental signal such thatthe output harmonic is cancelled leaving the desired signal alone. The weights of ANN are adjustedby output harmonic, which is isolated by a bandpass filter. The above concept is used as a basis forthe development of adaptive harmonic cancellation (AHC) algorithm. Simulation results performedwith a hydraulic system demonstrate the efficiency and validity of the proposed AHC control scheme.
基金Supported by the Key Scientific Research Fund of Inner Mongolian Educational Bureau (NJ04115)
文摘A complex-valued harmonic functions that are univalent and sense preserving in the unit disk U can be written in the form f = h + g^-, where h and g are analytic in U. We define and investigate a new class SHPλ(α,β)by generalized Salagean operator of harmonic univalent functions. We give sufficient coefficient conditions for normalized harmonic functions in the class SHPλ(α,β) These conditions are also shown to be necessary when the coefficients are negative. This leads to distortion bounds and extreme points.
文摘Since the dead zone phenomenon occurs in electro-hydraulic servo system, the output of the system corresponding to a sinusoidal input contains higher harmonic besides the fundamental input, which causes harmonic distortion of the output signal. The method for harmonic cancellation based on adaptive filter is proposed. The task is accomplished by generating reference signals with frequency that should be eliminated from the output. The reference inputs are weighted by the adaptive filter in such a way that it closely matches the harmonic. The output of the adaptive filter is a harmonic replica and is injected to the fundamental signal such that the output harmonic is cancelled leaving the desired signal alone, and the total harmonic distortion (THD) is greatly reduced. The weights of filter are adjusted on-line according to the control error by using least-mean-square (LMS) algorithm. Simulation results performed with a hydraulic system demonstrate the efficiency and validity of the proposed adaptive feed-forward compensator (AFC) control scheme
基金Foundation item: Supported by the Natural Science Foundation of Inner Mongolia(2009MS0113) Supported by the Higher School Research Foundation of Inner Mongolia(NJzy08150)
文摘A complex-valued harmonic function that is univalent and sense preserving in the unit disk U can be written in the form of f = h + g,where h and g are analytic in U.We define and investigate a new class LH_λ(α,β) by generalized Salagean operator of harmonic univalent functions.We give sufficient coefficient conditions for normalized harmonic functions in the class LH_λ(α,β).These conditions are also shown to be necessary when the coefficients are negative.This leads to distortion bounds and extreme points.
文摘We introduce a new class of complex valued harmonic functions associated with Wright hypergeometric functions which are orientation preserving and univalent in the open unit disc. Further we define, Wright generalized operator on harmonic function and investigate the coefficient bounds, distortion inequalities and extreme points for this generalized class of functions.
文摘Like others countries of the world, in Niger also, we are witnessing an increasing use of non-linear electric loads in the domestic, hospital and industrial sectors. However, these loads degrade the shape of the electrical signal and cause disastrous effects to the equipment of the distribution system and the devices which are connected to the network. This article highlights the presence of electric harmonics in the distribution network in Niamey city. In order to do this, measurements were taken at the secondary level of the substations using an energy quality analyze r (FLUKE 1735). By using this measuring instrument, we quantified the voltage and current Total Harmonic Distortion (THD) in the three substations. The results obtained show that, although the statutable rates set by the standards are not exceeded for phase conductors, the neutral contains a very critical percentage of distortion on the residential and hospital substations. Moreover, this assessment made it possible to observe the variation of harmonics in the presence of voltage drops.
文摘The contribution of Renewable Energy Resources(RER)in the process of power generation is significantly high in the recent days since it paves the way for overcoming the issues like serious energy crisis and natural contamination.This paper deals with the renewable energy based micro-grid as it is regarded as the apt solution for integrating the RER with the electrical frameworks.As thefixed droop coefficients in conventional droop control approaches have caused various limitations like low power-sharing and sudden drops of grid voltage in the Direct Current(DC)side,the Harmonized Membership Fuzzy Logic(MFL)droop control is employed in this present study.This proposed droop control for the hybrid PV-wind-battery system with MFL assists in achieving proper power-sharing and minimizing Total Harmonic Distortion(THD)in the emer-gency micro-grid.It eradicates the deviations in voltage and frequency with itsflexible and robust operation.The THD is reduced and attains the value of 3.1%compared to the traditional droop control.The simulation results of harmo-nized MFL droop control are analogized with the conventional approaches to vali-date the performance of the proposed method.In addition,the experimental results provided by the Field Programmable Gate Array(FPGA)based laboratory setup built using a solar photovoltaic(PV)and wind Permanent Magnet Synchro-nous Generator(PMSG)reaffirms the design.
文摘Due to the operation of power semiconductor switching converters, the content of harmonic currents, which these switching converters take from the feed array, is still increasing. One of the possible ways of minimizing these currents is the use of pulse switching converters. On one hand, the original, characteristic harmonic ones are minimized, but, on the other hand, new frequencies caused by the modulation frequency appear in the current spectrum. The level of the currents of these frequencies is small and is scarcely dependent on the load of the converter. It may happen that the proportional value of the monitored harmonic one is high, although the absolute value is low. In the article presented, there is a description of the activity of the pulse voltage rectifier and an analysis of the current taken. The other part contains the results of the harmonic analysis of the stated current, including both the absolute and proportional values according to the load. In the conclusion, there are results of measurements of pulsed switching converters taken from the real measurement.
文摘The purpose of this work is to determine the appropriate allocation of a single tuned passive filter “STPF” in a real distribution network at Tala city to prevent harmonic distortion caused by nonlinear loads. This design will cover the ideal filter parameter as well as the best filter position. The filter design is based on single and multi-objective functions that optimize the cost of the proposed filters, real power losses, total harmonic distortion “THD,” and individual harmonic distortion “IHD”. Upper and lower limitations for filter parameters, quality factor, voltage and harmonic distortion limits are determined using inequality constraints. This will be done under the equality constraint of power balance. The challenge of optimization is solved using two modern algorithms, jellyfish optimization technique “JFOT” and arithmetic optimization algorithm “AOA”, in which the placements of the filters and their parameters are selected. IEEE 33-bus radial system and an actual system as a part of the Egyptian network at Tala city are used for demonstrating the results obtained by the proposed techniques. The results reveal that the system’s harmonic distortion of current and voltage is reduced less than the limitations of the IEEE 519 standards.