Usually,rural areas can be electrified via three-phase distribution transformers with relatively large capacities.In such areas,low voltage lines are used for long distances,which cause power losses and voltage drop f...Usually,rural areas can be electrified via three-phase distribution transformers with relatively large capacities.In such areas,low voltage lines are used for long distances,which cause power losses and voltage drop for different types of consumers.Reducing losses and improving voltage profiles in rural distribution networks are significant challenges for electricity distribution companies.However different solutions were proposed in the literature to overcome these challenges,most of them face difficulties when applied in the conventional distribution network.To address the above issues,an applicable solution is proposed in this paper by installing a number of small-capacity distribution transformers instead of every single large-capacity transformer in rural areas.The proposed approach is implemented in the branch network of Al-Hoqool village,which belongs to the Nineveh distribution network.The network has been inspected on-site,drawn,and analyzed using the electrical systems analysis program(ETAP).The analysis showed that using the single-phase pole-mounted transformers can improve the voltage in the network’s end by 29%and enhance the voltage profile for all consumers.The analysis has also demonstrated that the modification can reduce the total power losses by 78%compared to the existing network.Concerning the economic aspect,the payback period for the proposed network is assigned to be 20 months.展开更多
The penetration of distributed energy resources(DERs) and energy-intensive resources is gradually increasing in active distribution networks(ADNs), which leads to frequent and severe voltage violation problems. As a d...The penetration of distributed energy resources(DERs) and energy-intensive resources is gradually increasing in active distribution networks(ADNs), which leads to frequent and severe voltage violation problems. As a densely distributed flexible resource in the future distribution network, 5G base station(BS) backup battery is used to regulate the voltage profile of ADN in this paper. First, the dispatchable potential of 5G BS backup batteries is analyzed. Considering the spatial-temporal characteristics of electric load for 5G BS, the dispatchable capacity of backup batteries at different time intervals is evaluated based on historical heat map data. Then, a voltage profile optimization model for ADN is established, consisting of 5G BS backup batteries and other voltage regulation resources. In this model, the charging/discharging behavior of backup batteries is based on its evaluation result of dispatchable capacity. Finally, the range of charging/discharging cost coefficients of 5G BS that benefits ADN and 5G operators are analyzed respectively. Further, an incentive policy for 5G operators is proposed. Under this policy, the charging/discharging cost coefficients of 5G BS can achieve a win-win situation for ADN and 5G operators. As an emerging flexible resource in ADN, the effectiveness and economy of 5G BS backup batteries participating in voltage profile optimization are verified in a test distribution network.展开更多
With multiple microgrids(MGs)integrated into power distribution networks in a distributed manner,the penetration of renewable energy like photovoltaic(PV)power generation surges.However,the operation of power distribu...With multiple microgrids(MGs)integrated into power distribution networks in a distributed manner,the penetration of renewable energy like photovoltaic(PV)power generation surges.However,the operation of power distribution networks is challenged by the issues of multiple power flow directions and voltage security.Accordingly,an efficient voltage control strategy is needed to ensure voltage security against ever-changing operating conditions,especially when the network topology information is absent or inaccurate.In this paper,we propose a novel data-driven voltage profile improvement model,denoted as system-wide composite adaptive network(SCAN),which depends on operational data instead of network topology details in the context of power distribution networks integrated with multiple MGs.Unlike existing studies that realize topology identification and decisionmaking optimization in sequence,the proposed end-to-end model determines the optimal voltage control decisions in one shot.More specifically,the proposed model consists of four modules,Pre-training Network and modified interior point methods with adversarial networks(Modified IPMAN)as core modules,and discriminator generative adversarial network(Dis-GAN)and Volt convolutional neural network(Volt-CNN)as ancillary modules.In particular,the generator in SCAN is trained by the core modules in sequence so as to form an end-to-end mode from data to decision.Numerical experiments based on IEEE 33-bus and 123-bus systems have validated the effectiveness and efficiency of the proposed method.展开更多
Voltage profiles of feeders with the connection of distributed generations(DGs) were investigated.A unified typical load distribution model was established.Based on this model,exact expressions of feeder voltage profi...Voltage profiles of feeders with the connection of distributed generations(DGs) were investigated.A unified typical load distribution model was established.Based on this model,exact expressions of feeder voltage profile with single and double DGs were derived and used to analyze the impact of DG's location and capacity on the voltage profile quantitatively.Then,a general formula of the voltage profile was derived.The limitation of single DG and necessity of multiple DGs for voltage regulation were also discussed.Through the simulation,voltage profiles of feeders with single and double DGs were compared.The voltage excursion rate is 7.40% for only one DG,while 2.48% and 2.36% for double DGs.It is shown that the feeder voltage can be retained in a more appropriate range with multiple DGs than with only one DG.Distributing the total capacity of DGs is better than concentrating it at one point.展开更多
The fast switching behaviors of wide bandgap devices bring some challenges such as high du/dt and limited short-circuit current withstand capability to the reliable operation of the motor drives.The current-source-inv...The fast switching behaviors of wide bandgap devices bring some challenges such as high du/dt and limited short-circuit current withstand capability to the reliable operation of the motor drives.The current-source-inverter(CSI)provides a promising solution in mitigating those challenges by owning the DC-link choke,the reverse-voltage blocking switches and AC commutation capacitors.To further reduce du/dt on switches of CSI fed motor drives,the technique of partial charging of capacitors have been investigated in this paper.By designing the series-connected and the parallel-connected partial-charging circuit for capacitors in DC-link,the voltage profile of CSI could be improved.Specifically,the zero-voltage-switching(ZVS)is achieved for main power switches,the du/dt is reduced and the overvoltage protection is presented.The working mechanism of the technique of partial charging of capacitor is described and one example is discussed on the dual three-phase motor drive.The experimental verification is presented to show the performance of partial charging technique for improving voltage profile of CSI fed motor drives.展开更多
The capacitor bank and synchronous condenser have been the only available sources of reactive power.Nowadays,most of the appliances use a power electronic interface for their connection.Applying a power electronic int...The capacitor bank and synchronous condenser have been the only available sources of reactive power.Nowadays,most of the appliances use a power electronic interface for their connection.Applying a power electronic interface addsmany features to these appliances.One of the promising features is their capability to interact with Volt-VAR programs.In this paper was investigated the reactive power interaction of the end-user appliances.For this purpose,the distribution network buses are ranked based on their effectiveness,followed by studying their interaction in the Volt-VAR program.To be able to consider the uncertainties,Probability Density Function(PDF)curve was discretized to represent different scenarios,and the reduction method was utilized to reduce the situations.展开更多
This work is part of the resolution of problems encountered on a 225 KV MANGOMBE-OYOMABANG line. This line is characterized by important technical losses, so that the voltage injected in the busbar is always lower tha...This work is part of the resolution of problems encountered on a 225 KV MANGOMBE-OYOMABANG line. This line is characterized by important technical losses, so that the voltage injected in the busbar is always lower than 200kV. The main objective of this work is to show the new solutions that can provide a combined FACTS-STATCOM and IPC 240 dual system on this line. Then to show the limitation of STATCOM compared to RPI 240. The results obtained allowed us to observe that in symmetrical operation the STATCOM improves the voltage profile on the busbar and in asymmetrical operation we found that it continues to regulate the voltage of each phase despite the unbalance. But the system remains too unbalanced because of the sequence current flow. The IPC 240 corrects this limitation, allowing asymmetrical operation of the line in an emergency while providing continuous service to the load.展开更多
This paper presents a new optimization study of the placement and size of a photovoltaic source(PVS)in a distribution grid,based on annual records of meteorological parameters(irradiance,temperature).Based on the reco...This paper presents a new optimization study of the placement and size of a photovoltaic source(PVS)in a distribution grid,based on annual records of meteorological parameters(irradiance,temperature).Based on the recorded data,the production output as well as the daily average power(24-h vector)of the PVS is extracted over the year.When a power vector is available,it can be used as an input when searching for the optimal size of the PVS.This allows to take into account the constraint of the variation of the power generated by this source considering the variation of the power consumed by the electrical loads during the whole day.A multi-objective fitness function has been considered.The latter minimizes the active losses and maximizes the voltage stability index during the day,while considering the constraints of the system,that is,the security,technical,geographical,and meteorological constraints.This problem was solved using the Non-dominated Sorting Genetic Algorithm NSGA-II optimization technique under MATLAB 2021.It was applied to the distribution network of Ghardaïa of 59 nodes.展开更多
A comparison of the effectiveness of installing reactive power compensators,such as shunt capacitors,static var compensators(SVCs),and static synchronous compensators(STATCOMs),was presented in large-scale power netwo...A comparison of the effectiveness of installing reactive power compensators,such as shunt capacitors,static var compensators(SVCs),and static synchronous compensators(STATCOMs),was presented in large-scale power networks.A suitable bus was first identified using modal analysis method.The single shunt capacitor,single SVC,and single STATCOM were installed separately on the most critical bus.The effects of the installation of different devices on power loss reduction,voltage profile improvement,and voltage stability margin enhancement were examined and compared for 57-and 118-bus transmission systems.The comparative study results show that SVC,and STATCOM are expensive compared to shunt capacitor,yet the effect of installing STATCOM is better than SVC and the effect of installing SVC is better than that of shunt capacitor in achieving power loss reduction,voltage profile improvement and voltage stability margin enhancement.展开更多
Power loss and voltage uncertainty are the major issues prevalently faced in the design of distribution systems.But such issues can be resolved through effective usage of networking reconfiguration that has a combinat...Power loss and voltage uncertainty are the major issues prevalently faced in the design of distribution systems.But such issues can be resolved through effective usage of networking reconfiguration that has a combination of Distributed Generation(DG)units from distribution networks.In this point of view,optimal placement and sizing of DGs are effective ways to boost the performance of power systems.The optimum allocation of DGs resolves various problems namely,power loss,voltage profile improvement,enhanced reliability,system stability,and performance.Several research works have been conducted to address the distribution system problems in terms of power loss,energy loss,voltage profile,and voltage stability depending upon optimal DG distribution.With this motivation,the current study designs a Chaotic Artificial Flora Optimization based on Optimal Placement and Sizing of DGs(CAFO-OPSDG)to enhance the voltage profiles and mitigate the power loss.Besides,the CAFO algorithm is derived from the incorporation of chaos theory concept into conventional artificial flora optimization AFO algorithm with an aim to enhance the global optimization abilities.The fitness function of CAFO-OPSDG algorithm involves voltage regulation,power loss minimization,and penalty cost.To consider the actual power system scenario,the penalty factor acts as an important element not only to minimize the total power loss but to increase the voltage profiles as well.The experimental validation of the CAFO-OPSDG algorithm was conducted against IEEE 33 Bus system and IEEE 69 Bus system.The outcomes were examined under various test scenarios.The results of the experiment established that the presented CAFO-OPSDG model is effective in terms of reducing the power loss and voltage deviation and boost-up the voltage profile for the specified system.展开更多
This paper presents an application of GRADE Algorithm based approach along with PV analysis to solve multi objective optimization problem of minimizing real power losses, improving the voltage profile and hence enhanc...This paper presents an application of GRADE Algorithm based approach along with PV analysis to solve multi objective optimization problem of minimizing real power losses, improving the voltage profile and hence enhancing the performance of power system. GRADE Algorithm is a hybrid technique combining genetic and differential evolution algorithms. Control variables considered are Generator bus voltages, MVAR at capacitor banks, transformer tap settings and reactive power generation at generator buses. The optimal values of the control variables are obtained by solving the multi objective optimization problem using GRADE Algorithm programmed using M coding in MATLAB platform. With the optimal setting for the control variables, Newton Raphson based power flow is performed for two test systems, viz, IEEE 30 bus system and IEEE 57 bus system for three loading conditions. Minimization of Real power loss and improvement of voltage profile obtained are compared with the results obtained using firefly and particle swarm optimization (PSO) techniques. Improvement of Loadability margin is established through PV curve plotted using continuation power flow with the real power load at the most affected bus as the bifurcation parameter. The simulated output shows improved results when compared to that of firefly and PSO techniques, in term of convergence time, reduction of real power loss, improvement of voltage profile and enhancement of loadability margin.展开更多
PV plants are increasing all over the world and they are becoming a distinct part of electric grids.Due to abundance of solar irradiation and almost constant amount of it in certain geographical latitudes,selection of...PV plants are increasing all over the world and they are becoming a distinct part of electric grids.Due to abundance of solar irradiation and almost constant amount of it in certain geographical latitudes,selection of proper capacity of PV plants depends mostly on available places for the site.In this paper,important measures for safe connection of a PV plant in terms of voltage requirements are addressed and several guidelines are introduced for this purpose.In addition,simulation results are included to prove some of the mentioned suggestions.A general algorithm is fi nally proposed to show the directions for safe connection of PV plants.展开更多
Ice accretion on aircraft encountering supercooled water droplets in clouds poses great risks to flight performance and safety.With the aim of optimizing the newly developed streamwise plasma heat knife method for ant...Ice accretion on aircraft encountering supercooled water droplets in clouds poses great risks to flight performance and safety.With the aim of optimizing the newly developed streamwise plasma heat knife method for anti-icing,a parametric investigation is carried out in this work.The influence of the detailed voltage profile on the heating effects of a Surface Dielectric Barrier Discharge driven by Nanosecond Pulses(NS-SDBD)is investigated,and a comparison of the antiicing performance among different configurations of streamwise plasma heat knife is made.The results show that columnar high-temperature regions produced by a multi-streamer discharge appear at small pulse rise time,but become diffuse as the pulse rise time increases.An optimal pulse rise time exists to provide a wide range and high value of temperature,which is found to be 150 ns for the setup in the present study.The influence of the pulse fall time is much weaker than that of the rise time.The range and value of the temperature decrease with increasing pulse fall time.A greater pulse width is found to improve the heating effect by increasing the discharge power.When a spanwise electrode is placed connecting the streamwise electrodes of the streamwise plasma heat knife at the airfoil leading edge,the anti-icing performance becomes poorer,whereas good performance is achieved when the spanwise electrode is at the edge of the streamwise electrodes.Based on this,a three-level configuration of the plasma heat knife is proposed,and its anti-icing performance is found to be much better than that of the original configuration.展开更多
The energy market in Libya is expected to face substantial changes in the next few years:electrical energy consumption will increase by 50% within the next 4 years.Therefore,there is a plan to gradually increase renew...The energy market in Libya is expected to face substantial changes in the next few years:electrical energy consumption will increase by 50% within the next 4 years.Therefore,there is a plan to gradually increase renewable energy sources in the power network by 2030 to 30%.Solar photovoltaic(PV)plants will play a significant role in the energy transition and the mix of energy sources in Libya.This article is a study conducted to investigate the challenges of power-flow management and power protection from integrating PV power plants into the Libyan power grid.In particular,a simulation model is built for the Kufra PV power plant(10 MW)with eight buses to assess the power network performance in terms of power quality such as voltage profile,power losses and harmonics.Furthermore,the impact of the PV plant on the short-circuit level and the power-protection system is presented under different operating conditions.The fault ride-through(FRT)is operated using standard ambient temperature and a wide range of irradiation intensity,and is verified by using the Libyan grid code.The results show that the integration of the PV plant into the grid has a significant impact on the short-circuit level and the FRT over the different fault levels and locations on the network.The initial period of the three-phase fault shows that the PV plant will be disconnected from the grid due to a decrease in the root mean square value voltages where the reactive and active power of the grid reach 938 MVAR and 261 MW,respectively.These results show that increasing the fault level will lead to an increase in injecting the active power.This work is considered the first extensive investigation into the challenges of modern power-flow management and power protection for the power network system in Libya.展开更多
With the growing number and capacity of photovoltaic(PV)installations connected to distribution networks,power quality issues related to voltage regulation are becoming relevant problems for power distribution compani...With the growing number and capacity of photovoltaic(PV)installations connected to distribution networks,power quality issues related to voltage regulation are becoming relevant problems for power distribution companies and for PV owners.In many countries,like Italy,this has required the revision of the standards concerning the connection to the public distribution network of distributed renewable generation.The new standards require a flexible operation of generation plants that have to be capable to change the active and reactive power dynamically in function of the network parameters(i.e.frequency and network local voltage)in local control or following external commands.Therefore,this paper investigates the use of smart inverter in a critical PV installation,where relevant voltage fluctuations exist.A case study,with real network parameters monitoring data and measurements,is discussed in the paper with the aim of showing how‘smart’features of new inverters can be implemented to increase PV plant integration in low voltage distribution networks.展开更多
文摘Usually,rural areas can be electrified via three-phase distribution transformers with relatively large capacities.In such areas,low voltage lines are used for long distances,which cause power losses and voltage drop for different types of consumers.Reducing losses and improving voltage profiles in rural distribution networks are significant challenges for electricity distribution companies.However different solutions were proposed in the literature to overcome these challenges,most of them face difficulties when applied in the conventional distribution network.To address the above issues,an applicable solution is proposed in this paper by installing a number of small-capacity distribution transformers instead of every single large-capacity transformer in rural areas.The proposed approach is implemented in the branch network of Al-Hoqool village,which belongs to the Nineveh distribution network.The network has been inspected on-site,drawn,and analyzed using the electrical systems analysis program(ETAP).The analysis showed that using the single-phase pole-mounted transformers can improve the voltage in the network’s end by 29%and enhance the voltage profile for all consumers.The analysis has also demonstrated that the modification can reduce the total power losses by 78%compared to the existing network.Concerning the economic aspect,the payback period for the proposed network is assigned to be 20 months.
基金supported by the National Natural Science Foundation of China (No.52077017)。
文摘The penetration of distributed energy resources(DERs) and energy-intensive resources is gradually increasing in active distribution networks(ADNs), which leads to frequent and severe voltage violation problems. As a densely distributed flexible resource in the future distribution network, 5G base station(BS) backup battery is used to regulate the voltage profile of ADN in this paper. First, the dispatchable potential of 5G BS backup batteries is analyzed. Considering the spatial-temporal characteristics of electric load for 5G BS, the dispatchable capacity of backup batteries at different time intervals is evaluated based on historical heat map data. Then, a voltage profile optimization model for ADN is established, consisting of 5G BS backup batteries and other voltage regulation resources. In this model, the charging/discharging behavior of backup batteries is based on its evaluation result of dispatchable capacity. Finally, the range of charging/discharging cost coefficients of 5G BS that benefits ADN and 5G operators are analyzed respectively. Further, an incentive policy for 5G operators is proposed. Under this policy, the charging/discharging cost coefficients of 5G BS can achieve a win-win situation for ADN and 5G operators. As an emerging flexible resource in ADN, the effectiveness and economy of 5G BS backup batteries participating in voltage profile optimization are verified in a test distribution network.
基金funded by the National Natural Science Foundation of China(Grant Nos.52007164,U2066601).
文摘With multiple microgrids(MGs)integrated into power distribution networks in a distributed manner,the penetration of renewable energy like photovoltaic(PV)power generation surges.However,the operation of power distribution networks is challenged by the issues of multiple power flow directions and voltage security.Accordingly,an efficient voltage control strategy is needed to ensure voltage security against ever-changing operating conditions,especially when the network topology information is absent or inaccurate.In this paper,we propose a novel data-driven voltage profile improvement model,denoted as system-wide composite adaptive network(SCAN),which depends on operational data instead of network topology details in the context of power distribution networks integrated with multiple MGs.Unlike existing studies that realize topology identification and decisionmaking optimization in sequence,the proposed end-to-end model determines the optimal voltage control decisions in one shot.More specifically,the proposed model consists of four modules,Pre-training Network and modified interior point methods with adversarial networks(Modified IPMAN)as core modules,and discriminator generative adversarial network(Dis-GAN)and Volt convolutional neural network(Volt-CNN)as ancillary modules.In particular,the generator in SCAN is trained by the core modules in sequence so as to form an end-to-end mode from data to decision.Numerical experiments based on IEEE 33-bus and 123-bus systems have validated the effectiveness and efficiency of the proposed method.
基金Projects(60904101,60972164) supported by the National Natural Science Foundation of ChinaProject(N090404009) supported by the Fundamental Research Funds for the Central UniversitiesProject(20090461187) supported by China Postdoctoral Science Foundation
文摘Voltage profiles of feeders with the connection of distributed generations(DGs) were investigated.A unified typical load distribution model was established.Based on this model,exact expressions of feeder voltage profile with single and double DGs were derived and used to analyze the impact of DG's location and capacity on the voltage profile quantitatively.Then,a general formula of the voltage profile was derived.The limitation of single DG and necessity of multiple DGs for voltage regulation were also discussed.Through the simulation,voltage profiles of feeders with single and double DGs were compared.The voltage excursion rate is 7.40% for only one DG,while 2.48% and 2.36% for double DGs.It is shown that the feeder voltage can be retained in a more appropriate range with multiple DGs than with only one DG.Distributing the total capacity of DGs is better than concentrating it at one point.
基金Supported by the Jiangsu Natural Science Foundation of China(BK20180013)in part by Shen Zhen Science and Technology Project(CYJ20180306174439784).
文摘The fast switching behaviors of wide bandgap devices bring some challenges such as high du/dt and limited short-circuit current withstand capability to the reliable operation of the motor drives.The current-source-inverter(CSI)provides a promising solution in mitigating those challenges by owning the DC-link choke,the reverse-voltage blocking switches and AC commutation capacitors.To further reduce du/dt on switches of CSI fed motor drives,the technique of partial charging of capacitors have been investigated in this paper.By designing the series-connected and the parallel-connected partial-charging circuit for capacitors in DC-link,the voltage profile of CSI could be improved.Specifically,the zero-voltage-switching(ZVS)is achieved for main power switches,the du/dt is reduced and the overvoltage protection is presented.The working mechanism of the technique of partial charging of capacitor is described and one example is discussed on the dual three-phase motor drive.The experimental verification is presented to show the performance of partial charging technique for improving voltage profile of CSI fed motor drives.
文摘The capacitor bank and synchronous condenser have been the only available sources of reactive power.Nowadays,most of the appliances use a power electronic interface for their connection.Applying a power electronic interface addsmany features to these appliances.One of the promising features is their capability to interact with Volt-VAR programs.In this paper was investigated the reactive power interaction of the end-user appliances.For this purpose,the distribution network buses are ranked based on their effectiveness,followed by studying their interaction in the Volt-VAR program.To be able to consider the uncertainties,Probability Density Function(PDF)curve was discretized to represent different scenarios,and the reduction method was utilized to reduce the situations.
文摘This work is part of the resolution of problems encountered on a 225 KV MANGOMBE-OYOMABANG line. This line is characterized by important technical losses, so that the voltage injected in the busbar is always lower than 200kV. The main objective of this work is to show the new solutions that can provide a combined FACTS-STATCOM and IPC 240 dual system on this line. Then to show the limitation of STATCOM compared to RPI 240. The results obtained allowed us to observe that in symmetrical operation the STATCOM improves the voltage profile on the busbar and in asymmetrical operation we found that it continues to regulate the voltage of each phase despite the unbalance. But the system remains too unbalanced because of the sequence current flow. The IPC 240 corrects this limitation, allowing asymmetrical operation of the line in an emergency while providing continuous service to the load.
基金the deanship of Scientific Research at Jouf University for founding this work through research grant no(DSR2020-02-387).https://www.ju.edu.sa/.
文摘This paper presents a new optimization study of the placement and size of a photovoltaic source(PVS)in a distribution grid,based on annual records of meteorological parameters(irradiance,temperature).Based on the recorded data,the production output as well as the daily average power(24-h vector)of the PVS is extracted over the year.When a power vector is available,it can be used as an input when searching for the optimal size of the PVS.This allows to take into account the constraint of the variation of the power generated by this source considering the variation of the power consumed by the electrical loads during the whole day.A multi-objective fitness function has been considered.The latter minimizes the active losses and maximizes the voltage stability index during the day,while considering the constraints of the system,that is,the security,technical,geographical,and meteorological constraints.This problem was solved using the Non-dominated Sorting Genetic Algorithm NSGA-II optimization technique under MATLAB 2021.It was applied to the distribution network of Ghardaïa of 59 nodes.
文摘A comparison of the effectiveness of installing reactive power compensators,such as shunt capacitors,static var compensators(SVCs),and static synchronous compensators(STATCOMs),was presented in large-scale power networks.A suitable bus was first identified using modal analysis method.The single shunt capacitor,single SVC,and single STATCOM were installed separately on the most critical bus.The effects of the installation of different devices on power loss reduction,voltage profile improvement,and voltage stability margin enhancement were examined and compared for 57-and 118-bus transmission systems.The comparative study results show that SVC,and STATCOM are expensive compared to shunt capacitor,yet the effect of installing STATCOM is better than SVC and the effect of installing SVC is better than that of shunt capacitor in achieving power loss reduction,voltage profile improvement and voltage stability margin enhancement.
文摘Power loss and voltage uncertainty are the major issues prevalently faced in the design of distribution systems.But such issues can be resolved through effective usage of networking reconfiguration that has a combination of Distributed Generation(DG)units from distribution networks.In this point of view,optimal placement and sizing of DGs are effective ways to boost the performance of power systems.The optimum allocation of DGs resolves various problems namely,power loss,voltage profile improvement,enhanced reliability,system stability,and performance.Several research works have been conducted to address the distribution system problems in terms of power loss,energy loss,voltage profile,and voltage stability depending upon optimal DG distribution.With this motivation,the current study designs a Chaotic Artificial Flora Optimization based on Optimal Placement and Sizing of DGs(CAFO-OPSDG)to enhance the voltage profiles and mitigate the power loss.Besides,the CAFO algorithm is derived from the incorporation of chaos theory concept into conventional artificial flora optimization AFO algorithm with an aim to enhance the global optimization abilities.The fitness function of CAFO-OPSDG algorithm involves voltage regulation,power loss minimization,and penalty cost.To consider the actual power system scenario,the penalty factor acts as an important element not only to minimize the total power loss but to increase the voltage profiles as well.The experimental validation of the CAFO-OPSDG algorithm was conducted against IEEE 33 Bus system and IEEE 69 Bus system.The outcomes were examined under various test scenarios.The results of the experiment established that the presented CAFO-OPSDG model is effective in terms of reducing the power loss and voltage deviation and boost-up the voltage profile for the specified system.
文摘This paper presents an application of GRADE Algorithm based approach along with PV analysis to solve multi objective optimization problem of minimizing real power losses, improving the voltage profile and hence enhancing the performance of power system. GRADE Algorithm is a hybrid technique combining genetic and differential evolution algorithms. Control variables considered are Generator bus voltages, MVAR at capacitor banks, transformer tap settings and reactive power generation at generator buses. The optimal values of the control variables are obtained by solving the multi objective optimization problem using GRADE Algorithm programmed using M coding in MATLAB platform. With the optimal setting for the control variables, Newton Raphson based power flow is performed for two test systems, viz, IEEE 30 bus system and IEEE 57 bus system for three loading conditions. Minimization of Real power loss and improvement of voltage profile obtained are compared with the results obtained using firefly and particle swarm optimization (PSO) techniques. Improvement of Loadability margin is established through PV curve plotted using continuation power flow with the real power load at the most affected bus as the bifurcation parameter. The simulated output shows improved results when compared to that of firefly and PSO techniques, in term of convergence time, reduction of real power loss, improvement of voltage profile and enhancement of loadability margin.
文摘PV plants are increasing all over the world and they are becoming a distinct part of electric grids.Due to abundance of solar irradiation and almost constant amount of it in certain geographical latitudes,selection of proper capacity of PV plants depends mostly on available places for the site.In this paper,important measures for safe connection of a PV plant in terms of voltage requirements are addressed and several guidelines are introduced for this purpose.In addition,simulation results are included to prove some of the mentioned suggestions.A general algorithm is fi nally proposed to show the directions for safe connection of PV plants.
基金co-supported by the National Natural Science Foundation of China(Nos.12002384 and 11802341)National Science and Technology Major Project of China(No.J2019-Ⅱ-0014-0035)+1 种基金National Key Laboratory Fund of China(No.614220220200109)the Academician Workstation Foundation of the Green Aerotechnics Research Institute of Chongqing Jiaotong University,China(No.GATRI2020C06003)。
文摘Ice accretion on aircraft encountering supercooled water droplets in clouds poses great risks to flight performance and safety.With the aim of optimizing the newly developed streamwise plasma heat knife method for anti-icing,a parametric investigation is carried out in this work.The influence of the detailed voltage profile on the heating effects of a Surface Dielectric Barrier Discharge driven by Nanosecond Pulses(NS-SDBD)is investigated,and a comparison of the antiicing performance among different configurations of streamwise plasma heat knife is made.The results show that columnar high-temperature regions produced by a multi-streamer discharge appear at small pulse rise time,but become diffuse as the pulse rise time increases.An optimal pulse rise time exists to provide a wide range and high value of temperature,which is found to be 150 ns for the setup in the present study.The influence of the pulse fall time is much weaker than that of the rise time.The range and value of the temperature decrease with increasing pulse fall time.A greater pulse width is found to improve the heating effect by increasing the discharge power.When a spanwise electrode is placed connecting the streamwise electrodes of the streamwise plasma heat knife at the airfoil leading edge,the anti-icing performance becomes poorer,whereas good performance is achieved when the spanwise electrode is at the edge of the streamwise electrodes.Based on this,a three-level configuration of the plasma heat knife is proposed,and its anti-icing performance is found to be much better than that of the original configuration.
基金the Deanship of Scientific Research at King Khalid University for funding this work through Research Groups Program under grant number RGP.2/81/43.
文摘The energy market in Libya is expected to face substantial changes in the next few years:electrical energy consumption will increase by 50% within the next 4 years.Therefore,there is a plan to gradually increase renewable energy sources in the power network by 2030 to 30%.Solar photovoltaic(PV)plants will play a significant role in the energy transition and the mix of energy sources in Libya.This article is a study conducted to investigate the challenges of power-flow management and power protection from integrating PV power plants into the Libyan power grid.In particular,a simulation model is built for the Kufra PV power plant(10 MW)with eight buses to assess the power network performance in terms of power quality such as voltage profile,power losses and harmonics.Furthermore,the impact of the PV plant on the short-circuit level and the power-protection system is presented under different operating conditions.The fault ride-through(FRT)is operated using standard ambient temperature and a wide range of irradiation intensity,and is verified by using the Libyan grid code.The results show that the integration of the PV plant into the grid has a significant impact on the short-circuit level and the FRT over the different fault levels and locations on the network.The initial period of the three-phase fault shows that the PV plant will be disconnected from the grid due to a decrease in the root mean square value voltages where the reactive and active power of the grid reach 938 MVAR and 261 MW,respectively.These results show that increasing the fault level will lead to an increase in injecting the active power.This work is considered the first extensive investigation into the challenges of modern power-flow management and power protection for the power network system in Libya.
文摘With the growing number and capacity of photovoltaic(PV)installations connected to distribution networks,power quality issues related to voltage regulation are becoming relevant problems for power distribution companies and for PV owners.In many countries,like Italy,this has required the revision of the standards concerning the connection to the public distribution network of distributed renewable generation.The new standards require a flexible operation of generation plants that have to be capable to change the active and reactive power dynamically in function of the network parameters(i.e.frequency and network local voltage)in local control or following external commands.Therefore,this paper investigates the use of smart inverter in a critical PV installation,where relevant voltage fluctuations exist.A case study,with real network parameters monitoring data and measurements,is discussed in the paper with the aim of showing how‘smart’features of new inverters can be implemented to increase PV plant integration in low voltage distribution networks.
