To speed up three-dimensional （3D） DC resistivity modeling, we present a new multigrid method, the aggregation-based algebraic multigrid method （AGMG）. We first discretize the differential equation of the secondar...To speed up three-dimensional （3D） DC resistivity modeling, we present a new multigrid method, the aggregation-based algebraic multigrid method （AGMG）. We first discretize the differential equation of the secondary potential field with mixed boundary conditions by using a seven-point finite-difference method to obtain a large sparse system of linear equations. Then, we introduce the theory behind the pairwise aggregation algorithms for AGMG and use the conjugate-gradient method with the V-cycle AGMG preconditioner （AGMG-CG） to solve the linear equations. We use typical geoelectrical models to test the proposed AGMG-CG method and compare the results with analytical solutions and the 3DDCXH algorithm for 3D DC modeling （3DDCXH）. In addition, we apply the AGMG-CG method to different grid sizes and geoelectrical models and compare it to different iterative methods, such as ILU-BICGSTAB, ILU-GCR, and SSOR-CG. The AGMG-CG method yields nearly linearly decreasing errors, whereas the number of iterations increases slowly with increasing grid size. The AGMG-CG method is precise and converges fast, and thus can improve the computational efficiency in forward modeling of three-dimensional DC resistivity.展开更多
Since the ocean bottom is a sedimentary environment wherein stratification is well developed, the use of an anisotropic model is best for studying its geology. Beginning with Maxwell＇s equations for an anisotropic mo...Since the ocean bottom is a sedimentary environment wherein stratification is well developed, the use of an anisotropic model is best for studying its geology. Beginning with Maxwell＇s equations for an anisotropic model, we introduce scalar potentials based on the divergence-free characteristic of the electric and magnetic （EM） fields. We then continue the EM fields down into the deep earth and upward into the seawater and couple them at the ocean bottom to the transmitting source. By studying both the DC apparent resistivity curves and their polar plots, we can resolve the anisotropy of the ocean bottom. Forward modeling of a high-resistivity thin layer in an anisotropic half-space demonstrates that the marine DC resistivity method in shallow water is very sensitive to the resistive reservoir but is not influenced by airwaves. As such, it is very suitable for oil and gas exploration in shallowwater areas but, to date, most modeling algorithms for studying marine DC resistivity are based on isotropic models. In this paper, we investigate one-dimensional anisotropic forward modeling for marine DC resistivity method, prove the algorithm to have high accuracy, and thus provide a theoretical basis for 2D and 3D forward modeling.展开更多
三有源桥DC-DC变换器(triple active bridge,TAB)具有功率密度大、电气隔离及控制灵活等优点,在直流电网中应用前景十分广阔。传统单移相控制策略下,三有源桥变换器内部存在较大回流功率,导致变换器的电流有效值和损耗增加。针对上述问...三有源桥DC-DC变换器(triple active bridge,TAB)具有功率密度大、电气隔离及控制灵活等优点,在直流电网中应用前景十分广阔。传统单移相控制策略下,三有源桥变换器内部存在较大回流功率,导致变换器的电流有效值和损耗增加。针对上述问题,该文提出一种以减小无功功率为目标的基波环流优化控制策略。首先从TAB变换器基本原理出发,通过傅里叶级数分解及相量分析法构建了TAB变换器的数学模型,得出输出端口有功功率和无功功率的表达式。然后,采用粒子群算法(particle swarm optimization,PSO)在全局范围内求解出最优移相角,构建相应的控制策略。通过改变负载模拟功率突变,对比分析单移相控制策略与所提优化控制策略下输出端口的响应特性。仿真和实验结果表明,该文所提优化控制策略能够在输出功率发生突变时,有效地减小输出端口的无功功率,提高系统效率。展开更多
为探究在集散式控制系统(distributed control system,DCS)危险排除过程中控制员不同信息搜索策略对排险任务绩效的影响及认知负荷的中介效应,基于虚拟现实技术、皮肤电采样和眼动追踪技术构建模拟DCS工控平台,招募20名相关专业被试参...为探究在集散式控制系统(distributed control system,DCS)危险排除过程中控制员不同信息搜索策略对排险任务绩效的影响及认知负荷的中介效应,基于虚拟现实技术、皮肤电采样和眼动追踪技术构建模拟DCS工控平台,招募20名相关专业被试参与模拟排险实验并对其认知负荷及排险绩效进行量化,使用眼动轨迹匹配法判断被试的信息搜索模式,研究认知负荷的中介效应及中介机理。研究结果表明:不同信息搜索策略会显著影响任务绩效;认知负荷对该影响的中介效应高达89.66%,表明信息搜索策略主要通过影响认知负荷来间接作用于排险任务绩效,认知负荷越高,任务绩效越低;逻辑系统搜索策略能通过高效图式匹配减少认知资源消耗,显著抑制认知负荷增长,任务绩效表现最佳;空间系统搜索较难抑制认知负荷,任务绩效较差;随机搜索被试认知负荷显著高于其他组,绩效表现最差;此外,不同认知负荷水平下被试的信息搜索策略没有明显转变倾向。研究结果可为DCS控制人员的考核和培训提供理论支撑。展开更多
Firstly, relevant stress properties of millisecond level breaking process and microsecond level commutation process of hybrid HVDC circuit breaker are studied in detail on the basis of the analysis for the application...Firstly, relevant stress properties of millisecond level breaking process and microsecond level commutation process of hybrid HVDC circuit breaker are studied in detail on the basis of the analysis for the application environment and topological structure and operating principles of hybrid circuit breakers, and key stress parameters in transient state process of two time dimensions are extracted. The established digital simulation circuit for PSCAD/EMTDC device-level operation of the circuit breaker has verified the stress properties of millisecond level breaking process and microsecond level commutation process. Then, equivalent test method, circuits and parameters based on LC power supply are proposed on the basis of stress extraction. Finally, the results of implemented breaking tests for complete 200 kV circuit breaker, 100 kV and 50 kV circuit breaker units, as well as single power electronic module have verified the accuracy of the simulation circuit and mathematical analysis. The result of this paper can be a guide to electrical structure and test system design of hybrid HVDC circuit breaker.展开更多
Previous studies have proposed higher requirements for the transient characteristics of a DC transformer used in a flexible high-voltage direct current(HVDC) system to achieve faster sampling speed and meet wider band...Previous studies have proposed higher requirements for the transient characteristics of a DC transformer used in a flexible high-voltage direct current(HVDC) system to achieve faster sampling speed and meet wider bandwidth requirements of the control and protection signal, and to eventually suppress the large transient fault current. In this study, a transient characteristics verification method is proposed for transient characteristics verification of a DC transformer used in a flexible HVDC system based on resampling technology and LabVIEW measurement technology after analyzing the key technology for transient characteristics verification of a DC transformer. A laboratory experiment for the transient characteristics of a full-fiber electronic DC transformer is conducted, and experimental results show that such verification method can be employed for frequency response and step response verification of a DC transformer at 10% of the rated voltage and current, and can eventually improve the screening of a DC transformer.展开更多
In order to solve the disadvantages caused by mechanical slide rheostat that has big errors and low precision,a novel voltage regulation method for high voltage DC power supply was introduced.The key of this method we...In order to solve the disadvantages caused by mechanical slide rheostat that has big errors and low precision,a novel voltage regulation method for high voltage DC power supply was introduced.The key of this method were digital potentiometer MAXIM 5455 and linear photoelectric coupling LOC110,and application programs were compiled using Visual Basic which was graphical compiling language,furthermore the communication between exterior and computer was carried out by ICP7044D module,in consequence the output value of high voltage DC power supply could be regulated with computer.The measured results showed that this method could accurately,conveniently and rapidly regulate the output value of high voltage DC power supply.展开更多
针对新能源可靠供电中的供需平衡问题,提出一种计及局部阴影工况的光储直流微电网能量管理。首先,针对光伏阵列在局部阴影等弱光照工况下,传统最大功率点跟踪方法在功率捕捉能力与能源利用效率方面的不足,利用蝠鲼优化算法(manta ray fo...针对新能源可靠供电中的供需平衡问题,提出一种计及局部阴影工况的光储直流微电网能量管理。首先,针对光伏阵列在局部阴影等弱光照工况下,传统最大功率点跟踪方法在功率捕捉能力与能源利用效率方面的不足,利用蝠鲼优化算法(manta ray foraging optimization,MRFO)的全局与局部搜索优势,提出一种结合MRFO的自适应电导增量法(manta ray foraging optimization-adaptive variable step-incremental conductance,MRFO-AVS-INC),以在特殊工况下实现对光伏出力的有效跟踪;其次,针对系统集成中存在的多源扰动问题,在储能系统的能量管理与控制方面,提出一种考虑蓄电池工作状态的改进下垂控制方法,通过引入蓄电池的荷电状态(state of charge,SOC)和健康状态(state of health,SOH)等参数,实现下垂系数的自适应调节,从而合理分配各蓄电池的输出功率;最后,在不同光照条件下对光储系统进行仿真验证。仿真结果表明,与基于粒子群算法的自适应变步长电导增量法(particle swarm optimization-adaptive variable stepincremental conductance,PSO-AVS-INC)及传统INC相比,MRFO-AVS-INC方法在收敛速度与跟踪稳定性方面表现更优;改进的自适应下垂控制有效实现了储能单元之间的状态均衡,延长了储能系统的整体使用寿命。展开更多
基金supported by the Natural Science Foundation of China(Nos.41404057,41674077 and 411640034)the Nuclear Energy Development Project of China,and the‘555’Project of Gan Po Excellent People
文摘To speed up three-dimensional （3D） DC resistivity modeling, we present a new multigrid method, the aggregation-based algebraic multigrid method （AGMG）. We first discretize the differential equation of the secondary potential field with mixed boundary conditions by using a seven-point finite-difference method to obtain a large sparse system of linear equations. Then, we introduce the theory behind the pairwise aggregation algorithms for AGMG and use the conjugate-gradient method with the V-cycle AGMG preconditioner （AGMG-CG） to solve the linear equations. We use typical geoelectrical models to test the proposed AGMG-CG method and compare the results with analytical solutions and the 3DDCXH algorithm for 3D DC modeling （3DDCXH）. In addition, we apply the AGMG-CG method to different grid sizes and geoelectrical models and compare it to different iterative methods, such as ILU-BICGSTAB, ILU-GCR, and SSOR-CG. The AGMG-CG method yields nearly linearly decreasing errors, whereas the number of iterations increases slowly with increasing grid size. The AGMG-CG method is precise and converges fast, and thus can improve the computational efficiency in forward modeling of three-dimensional DC resistivity.
基金financially supported by the National Hi-tech Research and Development Program of China(863 Program)(No.2012AA09A20103)
文摘Since the ocean bottom is a sedimentary environment wherein stratification is well developed, the use of an anisotropic model is best for studying its geology. Beginning with Maxwell＇s equations for an anisotropic model, we introduce scalar potentials based on the divergence-free characteristic of the electric and magnetic （EM） fields. We then continue the EM fields down into the deep earth and upward into the seawater and couple them at the ocean bottom to the transmitting source. By studying both the DC apparent resistivity curves and their polar plots, we can resolve the anisotropy of the ocean bottom. Forward modeling of a high-resistivity thin layer in an anisotropic half-space demonstrates that the marine DC resistivity method in shallow water is very sensitive to the resistive reservoir but is not influenced by airwaves. As such, it is very suitable for oil and gas exploration in shallowwater areas but, to date, most modeling algorithms for studying marine DC resistivity are based on isotropic models. In this paper, we investigate one-dimensional anisotropic forward modeling for marine DC resistivity method, prove the algorithm to have high accuracy, and thus provide a theoretical basis for 2D and 3D forward modeling.
文摘三有源桥DC-DC变换器(triple active bridge,TAB)具有功率密度大、电气隔离及控制灵活等优点,在直流电网中应用前景十分广阔。传统单移相控制策略下,三有源桥变换器内部存在较大回流功率,导致变换器的电流有效值和损耗增加。针对上述问题,该文提出一种以减小无功功率为目标的基波环流优化控制策略。首先从TAB变换器基本原理出发,通过傅里叶级数分解及相量分析法构建了TAB变换器的数学模型,得出输出端口有功功率和无功功率的表达式。然后,采用粒子群算法(particle swarm optimization,PSO)在全局范围内求解出最优移相角,构建相应的控制策略。通过改变负载模拟功率突变,对比分析单移相控制策略与所提优化控制策略下输出端口的响应特性。仿真和实验结果表明,该文所提优化控制策略能够在输出功率发生突变时,有效地减小输出端口的无功功率,提高系统效率。
文摘为探究在集散式控制系统(distributed control system,DCS)危险排除过程中控制员不同信息搜索策略对排险任务绩效的影响及认知负荷的中介效应,基于虚拟现实技术、皮肤电采样和眼动追踪技术构建模拟DCS工控平台,招募20名相关专业被试参与模拟排险实验并对其认知负荷及排险绩效进行量化,使用眼动轨迹匹配法判断被试的信息搜索模式,研究认知负荷的中介效应及中介机理。研究结果表明:不同信息搜索策略会显著影响任务绩效;认知负荷对该影响的中介效应高达89.66%,表明信息搜索策略主要通过影响认知负荷来间接作用于排险任务绩效,认知负荷越高,任务绩效越低;逻辑系统搜索策略能通过高效图式匹配减少认知资源消耗,显著抑制认知负荷增长,任务绩效表现最佳;空间系统搜索较难抑制认知负荷,任务绩效较差;随机搜索被试认知负荷显著高于其他组,绩效表现最差;此外,不同认知负荷水平下被试的信息搜索策略没有明显转变倾向。研究结果可为DCS控制人员的考核和培训提供理论支撑。
基金supported by SGCC Scientific and Technological Project(52110116004W)
文摘Firstly, relevant stress properties of millisecond level breaking process and microsecond level commutation process of hybrid HVDC circuit breaker are studied in detail on the basis of the analysis for the application environment and topological structure and operating principles of hybrid circuit breakers, and key stress parameters in transient state process of two time dimensions are extracted. The established digital simulation circuit for PSCAD/EMTDC device-level operation of the circuit breaker has verified the stress properties of millisecond level breaking process and microsecond level commutation process. Then, equivalent test method, circuits and parameters based on LC power supply are proposed on the basis of stress extraction. Finally, the results of implemented breaking tests for complete 200 kV circuit breaker, 100 kV and 50 kV circuit breaker units, as well as single power electronic module have verified the accuracy of the simulation circuit and mathematical analysis. The result of this paper can be a guide to electrical structure and test system design of hybrid HVDC circuit breaker.
基金supported by the State Grid Corporation Science and Technology Project(No.JL71-15-039)
文摘Previous studies have proposed higher requirements for the transient characteristics of a DC transformer used in a flexible high-voltage direct current(HVDC) system to achieve faster sampling speed and meet wider bandwidth requirements of the control and protection signal, and to eventually suppress the large transient fault current. In this study, a transient characteristics verification method is proposed for transient characteristics verification of a DC transformer used in a flexible HVDC system based on resampling technology and LabVIEW measurement technology after analyzing the key technology for transient characteristics verification of a DC transformer. A laboratory experiment for the transient characteristics of a full-fiber electronic DC transformer is conducted, and experimental results show that such verification method can be employed for frequency response and step response verification of a DC transformer at 10% of the rated voltage and current, and can eventually improve the screening of a DC transformer.
基金Project Supported by National Natural Science Foundation of China（50637020）.
文摘In order to solve the disadvantages caused by mechanical slide rheostat that has big errors and low precision,a novel voltage regulation method for high voltage DC power supply was introduced.The key of this method were digital potentiometer MAXIM 5455 and linear photoelectric coupling LOC110,and application programs were compiled using Visual Basic which was graphical compiling language,furthermore the communication between exterior and computer was carried out by ICP7044D module,in consequence the output value of high voltage DC power supply could be regulated with computer.The measured results showed that this method could accurately,conveniently and rapidly regulate the output value of high voltage DC power supply.
文摘针对新能源可靠供电中的供需平衡问题,提出一种计及局部阴影工况的光储直流微电网能量管理。首先,针对光伏阵列在局部阴影等弱光照工况下,传统最大功率点跟踪方法在功率捕捉能力与能源利用效率方面的不足,利用蝠鲼优化算法(manta ray foraging optimization,MRFO)的全局与局部搜索优势,提出一种结合MRFO的自适应电导增量法(manta ray foraging optimization-adaptive variable step-incremental conductance,MRFO-AVS-INC),以在特殊工况下实现对光伏出力的有效跟踪;其次,针对系统集成中存在的多源扰动问题,在储能系统的能量管理与控制方面,提出一种考虑蓄电池工作状态的改进下垂控制方法,通过引入蓄电池的荷电状态(state of charge,SOC)和健康状态(state of health,SOH)等参数,实现下垂系数的自适应调节,从而合理分配各蓄电池的输出功率;最后,在不同光照条件下对光储系统进行仿真验证。仿真结果表明,与基于粒子群算法的自适应变步长电导增量法(particle swarm optimization-adaptive variable stepincremental conductance,PSO-AVS-INC)及传统INC相比,MRFO-AVS-INC方法在收敛速度与跟踪稳定性方面表现更优;改进的自适应下垂控制有效实现了储能单元之间的状态均衡,延长了储能系统的整体使用寿命。
