Integrated energy system optimization scheduling can improve energy efficiency and low carbon economy.This paper studies an electric-gas-heat integrated energy system,including the carbon capture system,energy couplin...Integrated energy system optimization scheduling can improve energy efficiency and low carbon economy.This paper studies an electric-gas-heat integrated energy system,including the carbon capture system,energy coupling equipment,and renewable energy.An energy scheduling strategy based on deep reinforcement learning is proposed to minimize operation cost,carbon emission and enhance the power supply reliability.Firstly,the lowcarbon mathematical model of combined thermal and power unit,carbon capture system and power to gas unit(CCP)is established.Subsequently,we establish a low carbon multi-objective optimization model considering system operation cost,carbon emissions cost,integrated demand response,wind and photovoltaic curtailment,and load shedding costs.Furthermore,considering the intermittency of wind power generation and the flexibility of load demand,the low carbon economic dispatch problem is modeled as a Markov decision process.The twin delayed deep deterministic policy gradient(TD3)algorithm is used to solve the complex scheduling problem.The effectiveness of the proposed method is verified in the simulation case studies.Compared with TD3,SAC,A3C,DDPG and DQN algorithms,the operating cost is reduced by 8.6%,4.3%,6.1%and 8.0%.展开更多
This paper proposes a method to evaluate the reliability of power system with different capacities of wind power while considering carbon tax. The proposed method is a hybrid approach which combines Frequency and Dura...This paper proposes a method to evaluate the reliability of power system with different capacities of wind power while considering carbon tax. The proposed method is a hybrid approach which combines Frequency and Duration (F&D) method and Monte Carlo Simulation (MCS) method. MCS method is used to achieve a model to simulate the random status of power system. Also, the proposed method is applied on the IEEE 14-bus test system to investigate the effects of integrating different capacities of wind energy to the reliability of power system with considering carbon tax.展开更多
With the continuous development of science and technology, human life is more and more dependent on electric energy. As an important carrier, the safe and reliable operation of the distribution network is closely rela...With the continuous development of science and technology, human life is more and more dependent on electric energy. As an important carrier, the safe and reliable operation of the distribution network is closely related to the production and life of human beings. Facing the background of the gradual increase of power load and the increasing number of safety accidents of the power system, how to improve the reliability level of the distribution network has become a major issue of great concern to people. This paper mainly discusses the related problems of power supply reliability of power distribution network, introduces the basic situation of the development of power distribution network reliability in China, expounds the main factors affecting the current power supply reliability of power distribution network and puts forward the measures to improve the reliability of power distribution network. It is expected to provide some reference value for the development of power supply reliability of power distribution network.展开更多
At the end of last year, the editors from Power and Electrical Engineers interviewed Zhou Xiaoxin on "Fundamental Research on Enhancing Operation Reliability for Large-Scale Interconnected Power Grids", a pr...At the end of last year, the editors from Power and Electrical Engineers interviewed Zhou Xiaoxin on "Fundamental Research on Enhancing Operation Reliability for Large-Scale Interconnected Power Grids", a project of "973 Program". Mr. Zhou, the chief engineer of China Electric Power Research Institute(CEPRI) and an academician of Chinese Academy of Sciences, is the chief scientist in charge of this research project.展开更多
Reliability is a persistent challenge in power electronics, with component failures significantly compromising system performance. Capacitors, widely used in power converters for filtering, contribute to approximately...Reliability is a persistent challenge in power electronics, with component failures significantly compromising system performance. Capacitors, widely used in power converters for filtering, contribute to approximately 30% of failures, predominantly due to electrochemical corrosion leading to capacitance degradation and catastrophic breakdowns. This paper presents a novel capacitor-free solid-state power filter(SSPF) for three-phase inverters, offering a transformative approach to mitigate reliability issues associated with conventional inductor-capacitor(LC) and active output filters(AOFs). Unlike AOFs, which depend on compact LC structures, the SSPF eliminates capacitors entirely, circumventing their inherent failure modes. Leveraging advanced solid-state devices and transformer technology, the SSPF achieves superior filtering performance, enhances system reliability, and significantly reduces component count, utilizing half the metal-oxidesemiconductor field effect transistor(MOSFET) switches required by AOFs. This design not only lowers costs but also improves efficiency. Simulation and experimental results demonstrate the SSPF's capability to deliver a sinusoidal output voltage at the fundamental frequency. These attributes position the SSPF as a robust, cost-effective, and innovative solution for modern power electronics applications.展开更多
This paper suggests a combined novel control strategy for DFIG based wind power systems(WPS)under both nonlinear and unbalanced load conditions.The combined control approach is designed by coordinating the machine sid...This paper suggests a combined novel control strategy for DFIG based wind power systems(WPS)under both nonlinear and unbalanced load conditions.The combined control approach is designed by coordinating the machine side converter(MSC)and the load side converter(LSC)control approaches.The proposed MSC control approach is designed by using a model predictive control(MPC)approach to generate appropriate real and reactive power.The MSC controller selects an appropriate rotor voltage vector by using a minimized optimization cost function for the converter operation.It shows its superiority by eliminating the requirement of transformation,switching table,and the PWM techniques.The proposed MSC reduces the cost,complexity,and computational burden of the WPS.On the other hand,the LSC control approach is designed by using a mathematical morphological technique(MMT)for appropriate DC component extraction.Due to the appropriate DC-component extraction,the WPS can compensate the harmonics during both steady and dynamic states.Further,the LSC controller also provides active power filter operation even under the shutdown of WPS condition.To verify the applicability of coordinated control operation,the WPS-based microgrid system is tested under various test conditions.The proposed WPS is designed by using a MATLAB/Simulink software.展开更多
The TBS （telecommunications base stations） on remote sites in the northern part of Cameroon are mainly supplied by a system of two generating units. Only a few TBS located in the Waza and Benue National Parks are po...The TBS （telecommunications base stations） on remote sites in the northern part of Cameroon are mainly supplied by a system of two generating units. Only a few TBS located in the Waza and Benue National Parks are powered by a PV （photovoltaic） solar system to avoid any disturbance to wildlife. It is against this background that we decided to do a comparative study on these two systems. This study focuses on the reliability of electrical quantities, the environmental impact and the installation and operating costs of these two major systems namely the GU （generating unit） system comprising two generating units and the PV system. In conducting this study, we took a sample of TBS including those located in the Badjouma and Waza localities. After collecting data from mobile telephony operators, measurements of electrical quantities on the sites for twelve consecutive months and updating costs, their operation reveal indicators that are surprising, to say the least. Concerning the reliability index, the PV system is estimated at 99.9% as against 97.8% for the GU system. As for environmental impact, the mass of CO2 released by the GU system reached 1,707.5 tons in 25 years for a single TBS while the PV system produced no emissions. In addition to its contribution to climate change, the GU system pollutes its immediate environment through the spillage of waste and production of deafening noise. On the other hand, economic analysis shows mixed results. The GU system has a lower installation cost of $6,640 as against $174,550 for the PV system, whose investment cost is its main handicap. Regarding operating costs, the GU system peaks at $923,940 in 25 years while the PV system requires only $487,550 for the same duration.展开更多
Reliability level of HVDC power transmission systems becomes an important factor impacting the entire power grid.The author analyzes the reliability of HVDC power transmission systems owned by SGCC since 2003 in respe...Reliability level of HVDC power transmission systems becomes an important factor impacting the entire power grid.The author analyzes the reliability of HVDC power transmission systems owned by SGCC since 2003 in respect of forced outage times,forced energy unavailability,scheduled energy unavailability and energy utilization eff iciency.The results show that the reliability level of HVDC power transmission systems owned by SGCC is improving.By analyzing different reliability indices of HVDC power transmission system,the maximum asset benef its of power grid can be achieved through building a scientif ic and reasonable reliability evaluation system.展开更多
The reliability of energy systems is strongly influenced by the prevailing climate conditions.With the increasing prevalence of renewable energy sources,the interdependence between energy and climate systems has becom...The reliability of energy systems is strongly influenced by the prevailing climate conditions.With the increasing prevalence of renewable energy sources,the interdependence between energy and climate systems has become even stronger.This study examines the impact of different spatial resolutions in climate modeling on energy grid reliability assessment,with the Texas interconnection between 2033 and 2043 serving as a pilot case study.Our preliminary findings indicate that while low-resolution climate simulations can provide a rough estimate of system reliability,high-resolution simulations can provide more informative assessment of low-adequacy extreme events.Furthermore,both high-and low-resolution assessments suggest the need to prepare for severe blackout events in winter due to extremely low temperatures.展开更多
Demand response(DR)is usually regarded as a valuable balancing and reserve resource that contributes to maintaining power balance and integrating renewable energies.However,the price elasticity curve of the DR resourc...Demand response(DR)is usually regarded as a valuable balancing and reserve resource that contributes to maintaining power balance and integrating renewable energies.However,the price elasticity curve of the DR resources is influenced by consumers’behavioral uncertainty and therefore is difficult to predict.Consequently,additional risk may be introduced to composite power system reliability.Considering that,this paper investigates a reliability assessment of composite power system considering both the merits and potential uncertainty involved in the DR.First,the psychological behavior and consumption behavior of consumers are characterized in the DR modeling.A novel DR uncertainty index(denoted as I^(U))measures uncertainty of consumer’s behavior when electricity price changes.Then,an advanced Sigmoid cloud model is proposed to depict the comprehensive uncertain mapping relationships between price and I^(U).Moreover,an improved demand elasticity matrix is proposed,in which price-quantity elastic coefficients are modified by the I^(U)index.Finally,a reliability assessment framework for a composite power system is developed considering the uncertain price-based DR model and a k-means algorithm is used to accelerate the assessment process.Accuracy and effectiveness of the proposed method are investigated through the case study on RBTS,RTS79 and RTS96 reliability test systems.展开更多
The variability of wind power generation requires the allocation of a flexible energy reserve which is capable of compensating for possible imbalances between the load and generation. To reduce the variability of wind...The variability of wind power generation requires the allocation of a flexible energy reserve which is capable of compensating for possible imbalances between the load and generation. To reduce the variability of wind power generation and loss of load in generation deficit, we propose operation strategies for coordinating battery energy storage with wind power generation. The effects of the operation strategies on system reliability are evaluated by the developed computation model that represents the main aspects and operation limitations of the batteries. The performance evaluation of the power system is based on the composite reliability indices of loss of load probability(LOLP) and expected energy not supplied(EENS), which is calculated through sequential Monte Carlo simulation. Tests are performed by the developed model with a tutorial system consisting of five busbars and the IEEE RTS system. The results show that the use of large-scale batteries is an alternative to physically guarantee the wind power plants and to act as an operation reserve to reduce the risk of loss of load.展开更多
Modern distribution network with high penetration of intermittent renewable sources and the so-called prosumers requires more reliable distribution automation(DA) system for safe operation and control. The design of o...Modern distribution network with high penetration of intermittent renewable sources and the so-called prosumers requires more reliable distribution automation(DA) system for safe operation and control. The design of optimal feeder terminal units(FTU)placement is critical and economical for the effective DA application. Previously proposed solutions of optimal FTU placement aiming to ensure the accuracy of state estimation(SE), typically include the following two main shortcomings: 1) only to obtain the optimal FTU placement in quantity, and the analysis of FTU location is not considered yet; 2) few consider the uncertainty of intermittent power injections in the analysis of state estimation. In this paper, a modified methodology of FTU placement is proposed not only aiming to ensure the accuracy of state estimation with the minimum number of meters, but also finding those specific FTU locations to guarantee the power service reliability. Moreover, the uncertainty models of those intermittent power injections are also considered by using probability density function(PDF). The resultant optimization problem is addressed by using the covariance matrix adaptation evolution strategy(CMA-ES). Case studies demonstrate the feasibility and effectiveness of the proposed methodology.展开更多
The reliability of power transformers is subject to service age and health condition.This paper proposes a practical model for the evaluation of two reliability indices:survival function(SF)and mean residual life(MRL)...The reliability of power transformers is subject to service age and health condition.This paper proposes a practical model for the evaluation of two reliability indices:survival function(SF)and mean residual life(MRL).In the proposed model,the periodical modeling of power transformers are considered for collecting the information on health conditions.The corresponding health condition is assumed to follow a continuous semi-Markov process for representing a state transition.The proportional hazard model(PHM)is introduced to incorporate service age and health condition into hazard rate.In addition,the proposed model derives the analytical formulas for and offers the analytical evaluation of SF and MRL.SF and MRL are calculated for new components and old components,respectively.In both cases,the proposed model offers rational results which are compared with those obtained from comparative models.The results obtained by the contrast of the proposed analytical method and the Monte Carlo method.The impact of differentmodel parameters and the coefficient of variation(CV)on reliability indices are discussed in the case studies.展开更多
This paper introduces the problems emerged in the developing process of Nanning Medium-voltage distribution network to adapt the progress of HV network. These problems are: (1) unreasonable structure (large amount of ...This paper introduces the problems emerged in the developing process of Nanning Medium-voltage distribution network to adapt the progress of HV network. These problems are: (1) unreasonable structure (large amount of radical type 10 kV lines); (2) one 10 kV line for each customer (causing difficulties for line corridors); (3) circuit breaker are widely used for MV customers (result in complicated substation structure); (4) lots of overhead 10 kV lines in urban area. Ring circuit, insulated cables, load break switches, and fast acting fuses etc. advanced technologies are proposed for the retrofit of urban distribution network.展开更多
As extreme weather events have become more frequent in recent years,improving the resilience and reliability of power systems has become an important area of concern.In this paper,a robust preventive-corrective securi...As extreme weather events have become more frequent in recent years,improving the resilience and reliability of power systems has become an important area of concern.In this paper,a robust preventive-corrective security-constrained optimal power flow(RO-PCSCOPF)model is proposed to improve power system reliability under N−k outages.Both the short-term emergency limit(STL)and the long-term operating limit(LTL)of the post-contingency power flow on the branch are considered.Compared with the existing robust corrective SCOPF model that only considers STL or LTL,the proposed ROPCSCOPF model can achieve a more reliable generation dispatch solution.In addition,this paper also summarizes and compares the solution methods for solving the N−k SCOPF problem.The computational efficiency of the classical Benders decomposition(BD)method,robust optimization(RO)method,and line outage distribution factor(LODF)method are investigated on the IEEE 24-bus Reliability Test System and 118-bus system.Simulation results show that the BD method has the worst computation performance.The RO method and the LODF method have comparable performance.However,the LODF method can only be used for the preventive SCOPF and not for the corrective SCOPF.The RO method can be used for both.展开更多
With shrinking transistor feature size,the fin-type field-effect transistor（FinFET） has become the most promising option in low-power circuit design due to its superior capability to suppress leakage.To support the ...With shrinking transistor feature size,the fin-type field-effect transistor（FinFET） has become the most promising option in low-power circuit design due to its superior capability to suppress leakage.To support the VLSI digital system flow based on logic synthesis,we have designed an optimized high-performance low-power FinFET standard cell library based on employing the mixed FBB/RBB technique in the existing stacked structure of each cell.This paper presents the reliability evaluation of the optimized cells under process and operating environment variations based on Monte Carlo analysis.The variations are modelled with Gaussian distribution of the device parameters and 10000 sweeps are conducted in the simulation to obtain the statistical properties of the worst-case delay and input-dependent leakage for each cell.For comparison,a set of non-optimal cells that adopt the same topology without employing the mixed biasing technique is also generated.Experimental results show that the optimized cells achieve standard deviation reduction of 39.1%and 30.7%at most in worst-case delay and inputdependent leakage respectively while the normalized deviation shrinking in worst-case delay and input-dependent leakage canbe up to 98.37%and 24.13%,respectively,which demonstrates that our optimized cells are less sensitive to variability and exhibit more reliability.展开更多
In the last years, with the advent of Smart Grids, many research and demonstration projects have seen the light in order to involve electric system in the implementation of advances in information and communication te...In the last years, with the advent of Smart Grids, many research and demonstration projects have seen the light in order to involve electric system in the implementation of advances in information and communication technologies, in order to improve network efficiency, reliability, security and quality of service. Before new implementations are performed, previous results have to be studied, and taken into account. In this line, this work presents the methodology, results and conclusions of the evaluation of the Smart Grid functionalities developed by 5 different DSOs during DISCERN project in order to select the optimal, cost-effective and most replicable solutions for the strategic development of the intelligence at medium voltage (MV) and low voltage (LV) networks.展开更多
This paper proposes a novel solution for the secondary system of a primary distribution substation. First an evaluation is made of the changes that are to be expected for distribution substations in the future. Distri...This paper proposes a novel solution for the secondary system of a primary distribution substation. First an evaluation is made of the changes that are to be expected for distribution substations in the future. Distributed generation, electric vehicles and other active resources will change the behavior of the distribution network in a manner that will have a great deal of implications for distribution substations. The question is how the role of the distribution substations will change when the visions of smart grids become reality. The proposed solution consists of bay level protection and control IEDs forming the backbone of the secondar？, system. The functionality is complemented with a substation level Station Computer, providing value added and advanced functionality. In addition required communication and time synchronization methods are presented. A life cycle cost evaluation is also performed on the proposed solution, and it is compared with the current dominant concept based exclusively on bay level devices.展开更多
基金supported in part by the Scientific Research Fund of Liaoning Provincial Education Department under Grant LQGD2019005in part by the Doctoral Start-up Foundation of Liaoning Province under Grant 2020-BS-141.
文摘Integrated energy system optimization scheduling can improve energy efficiency and low carbon economy.This paper studies an electric-gas-heat integrated energy system,including the carbon capture system,energy coupling equipment,and renewable energy.An energy scheduling strategy based on deep reinforcement learning is proposed to minimize operation cost,carbon emission and enhance the power supply reliability.Firstly,the lowcarbon mathematical model of combined thermal and power unit,carbon capture system and power to gas unit(CCP)is established.Subsequently,we establish a low carbon multi-objective optimization model considering system operation cost,carbon emissions cost,integrated demand response,wind and photovoltaic curtailment,and load shedding costs.Furthermore,considering the intermittency of wind power generation and the flexibility of load demand,the low carbon economic dispatch problem is modeled as a Markov decision process.The twin delayed deep deterministic policy gradient(TD3)algorithm is used to solve the complex scheduling problem.The effectiveness of the proposed method is verified in the simulation case studies.Compared with TD3,SAC,A3C,DDPG and DQN algorithms,the operating cost is reduced by 8.6%,4.3%,6.1%and 8.0%.
文摘This paper proposes a method to evaluate the reliability of power system with different capacities of wind power while considering carbon tax. The proposed method is a hybrid approach which combines Frequency and Duration (F&D) method and Monte Carlo Simulation (MCS) method. MCS method is used to achieve a model to simulate the random status of power system. Also, the proposed method is applied on the IEEE 14-bus test system to investigate the effects of integrating different capacities of wind energy to the reliability of power system with considering carbon tax.
文摘With the continuous development of science and technology, human life is more and more dependent on electric energy. As an important carrier, the safe and reliable operation of the distribution network is closely related to the production and life of human beings. Facing the background of the gradual increase of power load and the increasing number of safety accidents of the power system, how to improve the reliability level of the distribution network has become a major issue of great concern to people. This paper mainly discusses the related problems of power supply reliability of power distribution network, introduces the basic situation of the development of power distribution network reliability in China, expounds the main factors affecting the current power supply reliability of power distribution network and puts forward the measures to improve the reliability of power distribution network. It is expected to provide some reference value for the development of power supply reliability of power distribution network.
文摘At the end of last year, the editors from Power and Electrical Engineers interviewed Zhou Xiaoxin on "Fundamental Research on Enhancing Operation Reliability for Large-Scale Interconnected Power Grids", a project of "973 Program". Mr. Zhou, the chief engineer of China Electric Power Research Institute(CEPRI) and an academician of Chinese Academy of Sciences, is the chief scientist in charge of this research project.
基金curruntly supported by the Purdue University Office of Technology Commercialization under Track Code (PRF 71167-01)。
文摘Reliability is a persistent challenge in power electronics, with component failures significantly compromising system performance. Capacitors, widely used in power converters for filtering, contribute to approximately 30% of failures, predominantly due to electrochemical corrosion leading to capacitance degradation and catastrophic breakdowns. This paper presents a novel capacitor-free solid-state power filter(SSPF) for three-phase inverters, offering a transformative approach to mitigate reliability issues associated with conventional inductor-capacitor(LC) and active output filters(AOFs). Unlike AOFs, which depend on compact LC structures, the SSPF eliminates capacitors entirely, circumventing their inherent failure modes. Leveraging advanced solid-state devices and transformer technology, the SSPF achieves superior filtering performance, enhances system reliability, and significantly reduces component count, utilizing half the metal-oxidesemiconductor field effect transistor(MOSFET) switches required by AOFs. This design not only lowers costs but also improves efficiency. Simulation and experimental results demonstrate the SSPF's capability to deliver a sinusoidal output voltage at the fundamental frequency. These attributes position the SSPF as a robust, cost-effective, and innovative solution for modern power electronics applications.
基金Assistance provided by Council of scientific and industrial research(CSIR),Government of India,under the acknowledgment number 143460/2K19/1(File:09/969(0013)/2K20-EMR-I)and Siksha O Anusandhan(Deemed to be University).
文摘This paper suggests a combined novel control strategy for DFIG based wind power systems(WPS)under both nonlinear and unbalanced load conditions.The combined control approach is designed by coordinating the machine side converter(MSC)and the load side converter(LSC)control approaches.The proposed MSC control approach is designed by using a model predictive control(MPC)approach to generate appropriate real and reactive power.The MSC controller selects an appropriate rotor voltage vector by using a minimized optimization cost function for the converter operation.It shows its superiority by eliminating the requirement of transformation,switching table,and the PWM techniques.The proposed MSC reduces the cost,complexity,and computational burden of the WPS.On the other hand,the LSC control approach is designed by using a mathematical morphological technique(MMT)for appropriate DC component extraction.Due to the appropriate DC-component extraction,the WPS can compensate the harmonics during both steady and dynamic states.Further,the LSC controller also provides active power filter operation even under the shutdown of WPS condition.To verify the applicability of coordinated control operation,the WPS-based microgrid system is tested under various test conditions.The proposed WPS is designed by using a MATLAB/Simulink software.
文摘The TBS （telecommunications base stations） on remote sites in the northern part of Cameroon are mainly supplied by a system of two generating units. Only a few TBS located in the Waza and Benue National Parks are powered by a PV （photovoltaic） solar system to avoid any disturbance to wildlife. It is against this background that we decided to do a comparative study on these two systems. This study focuses on the reliability of electrical quantities, the environmental impact and the installation and operating costs of these two major systems namely the GU （generating unit） system comprising two generating units and the PV system. In conducting this study, we took a sample of TBS including those located in the Badjouma and Waza localities. After collecting data from mobile telephony operators, measurements of electrical quantities on the sites for twelve consecutive months and updating costs, their operation reveal indicators that are surprising, to say the least. Concerning the reliability index, the PV system is estimated at 99.9% as against 97.8% for the GU system. As for environmental impact, the mass of CO2 released by the GU system reached 1,707.5 tons in 25 years for a single TBS while the PV system produced no emissions. In addition to its contribution to climate change, the GU system pollutes its immediate environment through the spillage of waste and production of deafening noise. On the other hand, economic analysis shows mixed results. The GU system has a lower installation cost of $6,640 as against $174,550 for the PV system, whose investment cost is its main handicap. Regarding operating costs, the GU system peaks at $923,940 in 25 years while the PV system requires only $487,550 for the same duration.
文摘Reliability level of HVDC power transmission systems becomes an important factor impacting the entire power grid.The author analyzes the reliability of HVDC power transmission systems owned by SGCC since 2003 in respect of forced outage times,forced energy unavailability,scheduled energy unavailability and energy utilization eff iciency.The results show that the reliability level of HVDC power transmission systems owned by SGCC is improving.By analyzing different reliability indices of HVDC power transmission system,the maximum asset benef its of power grid can be achieved through building a scientif ic and reasonable reliability evaluation system.
文摘The reliability of energy systems is strongly influenced by the prevailing climate conditions.With the increasing prevalence of renewable energy sources,the interdependence between energy and climate systems has become even stronger.This study examines the impact of different spatial resolutions in climate modeling on energy grid reliability assessment,with the Texas interconnection between 2033 and 2043 serving as a pilot case study.Our preliminary findings indicate that while low-resolution climate simulations can provide a rough estimate of system reliability,high-resolution simulations can provide more informative assessment of low-adequacy extreme events.Furthermore,both high-and low-resolution assessments suggest the need to prepare for severe blackout events in winter due to extremely low temperatures.
基金supported by the National Natural Science Foundation of China(52107072).
文摘Demand response(DR)is usually regarded as a valuable balancing and reserve resource that contributes to maintaining power balance and integrating renewable energies.However,the price elasticity curve of the DR resources is influenced by consumers’behavioral uncertainty and therefore is difficult to predict.Consequently,additional risk may be introduced to composite power system reliability.Considering that,this paper investigates a reliability assessment of composite power system considering both the merits and potential uncertainty involved in the DR.First,the psychological behavior and consumption behavior of consumers are characterized in the DR modeling.A novel DR uncertainty index(denoted as I^(U))measures uncertainty of consumer’s behavior when electricity price changes.Then,an advanced Sigmoid cloud model is proposed to depict the comprehensive uncertain mapping relationships between price and I^(U).Moreover,an improved demand elasticity matrix is proposed,in which price-quantity elastic coefficients are modified by the I^(U)index.Finally,a reliability assessment framework for a composite power system is developed considering the uncertain price-based DR model and a k-means algorithm is used to accelerate the assessment process.Accuracy and effectiveness of the proposed method are investigated through the case study on RBTS,RTS79 and RTS96 reliability test systems.
文摘The variability of wind power generation requires the allocation of a flexible energy reserve which is capable of compensating for possible imbalances between the load and generation. To reduce the variability of wind power generation and loss of load in generation deficit, we propose operation strategies for coordinating battery energy storage with wind power generation. The effects of the operation strategies on system reliability are evaluated by the developed computation model that represents the main aspects and operation limitations of the batteries. The performance evaluation of the power system is based on the composite reliability indices of loss of load probability(LOLP) and expected energy not supplied(EENS), which is calculated through sequential Monte Carlo simulation. Tests are performed by the developed model with a tutorial system consisting of five busbars and the IEEE RTS system. The results show that the use of large-scale batteries is an alternative to physically guarantee the wind power plants and to act as an operation reserve to reduce the risk of loss of load.
基金supported by the National Natural Science Foundation of China(Grant No.51677025)State Grid Corporation of China(Grant No.52110417000A)+1 种基金Research Innovation Program for College Graduates(Grant No.KYLX16_0212)National Key Research&Development Project of China(Grant No.2017YFB0902801)
文摘Modern distribution network with high penetration of intermittent renewable sources and the so-called prosumers requires more reliable distribution automation(DA) system for safe operation and control. The design of optimal feeder terminal units(FTU)placement is critical and economical for the effective DA application. Previously proposed solutions of optimal FTU placement aiming to ensure the accuracy of state estimation(SE), typically include the following two main shortcomings: 1) only to obtain the optimal FTU placement in quantity, and the analysis of FTU location is not considered yet; 2) few consider the uncertainty of intermittent power injections in the analysis of state estimation. In this paper, a modified methodology of FTU placement is proposed not only aiming to ensure the accuracy of state estimation with the minimum number of meters, but also finding those specific FTU locations to guarantee the power service reliability. Moreover, the uncertainty models of those intermittent power injections are also considered by using probability density function(PDF). The resultant optimization problem is addressed by using the covariance matrix adaptation evolution strategy(CMA-ES). Case studies demonstrate the feasibility and effectiveness of the proposed methodology.
文摘The reliability of power transformers is subject to service age and health condition.This paper proposes a practical model for the evaluation of two reliability indices:survival function(SF)and mean residual life(MRL).In the proposed model,the periodical modeling of power transformers are considered for collecting the information on health conditions.The corresponding health condition is assumed to follow a continuous semi-Markov process for representing a state transition.The proportional hazard model(PHM)is introduced to incorporate service age and health condition into hazard rate.In addition,the proposed model derives the analytical formulas for and offers the analytical evaluation of SF and MRL.SF and MRL are calculated for new components and old components,respectively.In both cases,the proposed model offers rational results which are compared with those obtained from comparative models.The results obtained by the contrast of the proposed analytical method and the Monte Carlo method.The impact of differentmodel parameters and the coefficient of variation(CV)on reliability indices are discussed in the case studies.
文摘This paper introduces the problems emerged in the developing process of Nanning Medium-voltage distribution network to adapt the progress of HV network. These problems are: (1) unreasonable structure (large amount of radical type 10 kV lines); (2) one 10 kV line for each customer (causing difficulties for line corridors); (3) circuit breaker are widely used for MV customers (result in complicated substation structure); (4) lots of overhead 10 kV lines in urban area. Ring circuit, insulated cables, load break switches, and fast acting fuses etc. advanced technologies are proposed for the retrofit of urban distribution network.
基金This work was supported by the Education Department of Guangdong Province:New and Integrated Energy System Theory and Technology Research Group(No.2016KCXTD022)National Natural Science Foundation of China(No.51907031)+2 种基金Guangdong Basic and Applied Basic Research Foundation(Guangdong-Guangxi Joint Foundation)(No.2021A1515410009)China Scholarship CouncilBrunel University London BRIEF Funding。
文摘As extreme weather events have become more frequent in recent years,improving the resilience and reliability of power systems has become an important area of concern.In this paper,a robust preventive-corrective security-constrained optimal power flow(RO-PCSCOPF)model is proposed to improve power system reliability under N−k outages.Both the short-term emergency limit(STL)and the long-term operating limit(LTL)of the post-contingency power flow on the branch are considered.Compared with the existing robust corrective SCOPF model that only considers STL or LTL,the proposed ROPCSCOPF model can achieve a more reliable generation dispatch solution.In addition,this paper also summarizes and compares the solution methods for solving the N−k SCOPF problem.The computational efficiency of the classical Benders decomposition(BD)method,robust optimization(RO)method,and line outage distribution factor(LODF)method are investigated on the IEEE 24-bus Reliability Test System and 118-bus system.Simulation results show that the BD method has the worst computation performance.The RO method and the LODF method have comparable performance.However,the LODF method can only be used for the preventive SCOPF and not for the corrective SCOPF.The RO method can be used for both.
基金Project supported by the National Natural Science Foundation of China(No.61306040)the State Key Development Program for Basic Research of China(No.2015CB057201)+1 种基金the Beijing Natural Science Foundation(No.4152020)Natural Science Foundation of Guangdong Province,China(No.2015A030313147)
文摘With shrinking transistor feature size,the fin-type field-effect transistor（FinFET） has become the most promising option in low-power circuit design due to its superior capability to suppress leakage.To support the VLSI digital system flow based on logic synthesis,we have designed an optimized high-performance low-power FinFET standard cell library based on employing the mixed FBB/RBB technique in the existing stacked structure of each cell.This paper presents the reliability evaluation of the optimized cells under process and operating environment variations based on Monte Carlo analysis.The variations are modelled with Gaussian distribution of the device parameters and 10000 sweeps are conducted in the simulation to obtain the statistical properties of the worst-case delay and input-dependent leakage for each cell.For comparison,a set of non-optimal cells that adopt the same topology without employing the mixed biasing technique is also generated.Experimental results show that the optimized cells achieve standard deviation reduction of 39.1%and 30.7%at most in worst-case delay and inputdependent leakage respectively while the normalized deviation shrinking in worst-case delay and input-dependent leakage canbe up to 98.37%and 24.13%,respectively,which demonstrates that our optimized cells are less sensitive to variability and exhibit more reliability.
文摘In the last years, with the advent of Smart Grids, many research and demonstration projects have seen the light in order to involve electric system in the implementation of advances in information and communication technologies, in order to improve network efficiency, reliability, security and quality of service. Before new implementations are performed, previous results have to be studied, and taken into account. In this line, this work presents the methodology, results and conclusions of the evaluation of the Smart Grid functionalities developed by 5 different DSOs during DISCERN project in order to select the optimal, cost-effective and most replicable solutions for the strategic development of the intelligence at medium voltage (MV) and low voltage (LV) networks.
文摘This paper proposes a novel solution for the secondary system of a primary distribution substation. First an evaluation is made of the changes that are to be expected for distribution substations in the future. Distributed generation, electric vehicles and other active resources will change the behavior of the distribution network in a manner that will have a great deal of implications for distribution substations. The question is how the role of the distribution substations will change when the visions of smart grids become reality. The proposed solution consists of bay level protection and control IEDs forming the backbone of the secondar？, system. The functionality is complemented with a substation level Station Computer, providing value added and advanced functionality. In addition required communication and time synchronization methods are presented. A life cycle cost evaluation is also performed on the proposed solution, and it is compared with the current dominant concept based exclusively on bay level devices.
