With the structure of two air gaps and two rotors, the electromagnetic continuously variable transmission(EMCVT) is a novel power-split continuously variable transmission(CVT). There are two kinds of power flowing...With the structure of two air gaps and two rotors, the electromagnetic continuously variable transmission(EMCVT) is a novel power-split continuously variable transmission(CVT). There are two kinds of power flowing through the EMCVT, one is mechanical power and the other is electric power. In the mean time, there are three power ports in the EMCVT, one is the outer rotor named mechanical power port and the other two are the inner rotor and the stator named electric power ports. The mechanical power port is connected to the driving wheels through the final gear and the electric ports are connected to the batteries through the transducers. The two kinds of power are coupled on the outer rotor of the EMCVT. The EMCVT can be equipped on the conventional vehicle being regarded as the CVT and it also can be equipped on the hybrid electric vehicle(HEV) as the multi-energy sources assembly. The power flows of these two kinds of applications are analysed. The back electromotive force(EMF) equations are illatively studied and so the dynamic mathematic model is theorized. In order to certify the feasibility of the above theories, three simulations are carried out in allusion to the above two kinds of mentioned applications of the EMCVT and a five speed automatic transmission(AT) vehicle. The simulation results illustrate that the efficiency of the EMCVT vehicles is higher than that of the AT vehicle owed to the optimized operation area of the engine. Hence the fuel consumption of the EMCVT vehicles is knock-down.展开更多
A universal expression for the transmitted power to the flexible foundation via the finite continuous isolation system of asymmetry is derived where the concept of effective mobility for the coupled system with contin...A universal expression for the transmitted power to the flexible foundation via the finite continuous isolation system of asymmetry is derived where the concept of effective mobility for the coupled system with continuous contact points is put forward. On the basis of the theoretic calculation and analysis, effects of structure parameters of the system on the power flow transmission as well as on the isolation efficiency are fully investigated.展开更多
This paper is a further study of two papers [1] and [2], which were related to Ill-Conditioned Load Flow Problems and were published by IEEE Trans. PAS. The authors of this paper have some different opinions, for exam...This paper is a further study of two papers [1] and [2], which were related to Ill-Conditioned Load Flow Problems and were published by IEEE Trans. PAS. The authors of this paper have some different opinions, for example, the 11-bus system is not an ill-conditioned system. In addition, a new approach to solve Load Flow Problems, E-ψtc, is introduced. It is an explicit method;solving linear equations is not needed. It can handle very tough and very large systems. The advantage of this method has been fully proved by two examples. The authors give this new method a detailed description of how to use it to solve Load Flow Problems and successfully apply it to the 43-bus and the 11-bus systems. The authors also propose a strategy to test the reliability, and by solving gradient equations, this new method can answer if the solution exists or not.展开更多
As an effective emulator of ill-conditioned power flow,continuous Newton methods(CNMs)have been extensively investigated using explicit and implicit numerical integration algorithms.However,explicit CNMs often suffer ...As an effective emulator of ill-conditioned power flow,continuous Newton methods(CNMs)have been extensively investigated using explicit and implicit numerical integration algorithms.However,explicit CNMs often suffer from non-convergence due to their limited stability region,while implicit CNMs require additional iterative loops to solve nonlinear equations.To address this,we propose a semi-implicit version of CNM.We formulate the power flow equations as a set of differential algebraic equations(DAEs),and solve the DAEs with the stiffly accurate Rosenbrock type method(SARM).The proposed method succeeds the numerical robustness from the implicit CNM framework while prevents the iterative solution of nonlinear systems,hence revealing higher convergence speed and computation efficiency.We develop a novel 4-stage,3rd-order hyper-stable SARM with an embedded 2nd-order formula for adaptive step size control.This design enhances convergence through damping adjustment.Case studies on ill-conditioned systems verify the alleged performance.An algorithm extension for MATPOWER is made available on Github for benchmarking.展开更多
Based on an exact CAD model of hydro-mechanical continuously variable transmission (HMCVT) gearbox which can transmit 180 horsepower, virtual prototype of the HMCVT was built. Revolution speed of shafts, gears and c...Based on an exact CAD model of hydro-mechanical continuously variable transmission (HMCVT) gearbox which can transmit 180 horsepower, virtual prototype of the HMCVT was built. Revolution speed of shafts, gears and clutches of the HMCVT were calibrated by using results obtained by theoretical calculation and test methods. The needed power and torques of both mechanical power input shaft and hydropower input shaft were calculated by simulation. Hydraulic power distributing ratio and power flow of the system was also studied. The analysis results showed that cycle power was produced inevitably when the output shaft speed of HMCVT change smoothly during mechanical and hydraulic working state HM1 to HM4, and the instantaneous maximum cycle power was 39.5%. Then the overall transmission efficiency of HMCVT was studied, and the maximum overall efficiency of the system was about 87%. The results of the studies gave references to select suited engine and variable displacement pump for the HMCVT, and to develop rational speed control strategies for the HMCVT by changing displacement ratio of variable displacement pump.展开更多
随着可再生能源渗透率不断提高,电力系统运行不确定性显著增加.为应对风电不确定性对电力系统暂态稳定造成的影响,本文引入机会约束,将新能源出力的不确定性纳入暂态稳定约束最优潮流模型中.通过将传统的暂态稳定约束预防控制转化为机...随着可再生能源渗透率不断提高,电力系统运行不确定性显著增加.为应对风电不确定性对电力系统暂态稳定造成的影响,本文引入机会约束,将新能源出力的不确定性纳入暂态稳定约束最优潮流模型中.通过将传统的暂态稳定约束预防控制转化为机会约束优化问题,提出一种基于深度西格马点过程(deep Sigma point processes,DSPP)的机会约束暂态稳定预防控制方法,并采用连续域蚁群优化(ant colony optimization for continuous domains,ACOR)算法对控制策略进行迭代更新,以确保新生成的高质量解决方案能够持续替代旧方案.本文所提出的成本最小化方法不仅执行时间较短,还能有效管理能源资源,且在平均值和标准差等统计指标上优于传统方法.同时,ACOR算法在降低电力系统燃料成本的同时,确保了较高的精度和收敛性.最后,通过在IEEE39节点系统上的仿真结果表明,该方法在经济性、收敛稳定性和计算效率方面均优于传统方法.展开更多
The continuation power flow method combined with the Jacobi-Davidson method is presented to trace the critical eigenvalues for power system small signal stability analysis. The continuation power flow based on a predi...The continuation power flow method combined with the Jacobi-Davidson method is presented to trace the critical eigenvalues for power system small signal stability analysis. The continuation power flow based on a predictor- corrector technique is applied to evaluate a continuum of steady state power flow solutions as system parameters change;meanwhile, the critical eigenvalues are found by the Jacobi-Davidson method, and thereby the trajectories of the critical eigenvalues, Hopf bifurcation and saddle node bifurcation points can also be found by the proposed method. The numerical simulations are studied in the IEEE 30-bus test system.展开更多
As the integration of distributed generations(DGs)transforms the traditional distribution network into the active distribution network,voltage stability assessments(VSA)of transmission grid and distribution grid are n...As the integration of distributed generations(DGs)transforms the traditional distribution network into the active distribution network,voltage stability assessments(VSA)of transmission grid and distribution grid are not suitable to be studied separately.This paper presents a distributed continuation power flow method for VSA of global transmission and distribution grid.Two different parameterization schemes are adopted to guarantee the coherence of load growth in transmission and distribution grids.In the correction step,the boundary bus voltage,load parameter and equivalent power are communicated between the transmission and distribution control centers to realize the distributed computation of load margin.The optimal multiplier technique is used to improve the convergence of the proposed method.The three-phase unbalanced characteristic of distribution networks and the reactive capability limits of DGs are considered.Simulation results on two integrated transmission and distribution test systems show that the proposed method is effective.展开更多
Photoacoustic Doppler flow measurement based on continuous wave laser excitation owns the merit of clearly presenting the Doppler power spectra.Extending this technique to dual wavelengths can gain the spectral inform...Photoacoustic Doppler flow measurement based on continuous wave laser excitation owns the merit of clearly presenting the Doppler power spectra.Extending this technique to dual wavelengths can gain the spectral information of the flow sample extra to the flow speed information.An experimental system with two laser diodes respectively operated at 405 nm and 660 nm wavelengths is built and the flow measurement with black and red dyed polystyrene beads is performed.The measured Doppler power spectra can vividly reflect the flow speed,the flow direction,as well as the bead color.Since it is straightforward to further apply the same principle to multiple wavelengths,we can expect this type of spectroscopic photoacoustic Doppler flow measurement will be developed in the near future which will be very useful for studying the metabolism of the slowly moving red blood cell inside microvessels.展开更多
基金supported by National Natural Science Foundation of China(No.50605020)Guangdong Provincial Science and Technology Project of China(No.2006A10501001).
摘要With the structure of two air gaps and two rotors, the electromagnetic continuously variable transmission(EMCVT) is a novel power-split continuously variable transmission(CVT). There are two kinds of power flowing through the EMCVT, one is mechanical power and the other is electric power. In the mean time, there are three power ports in the EMCVT, one is the outer rotor named mechanical power port and the other two are the inner rotor and the stator named electric power ports. The mechanical power port is connected to the driving wheels through the final gear and the electric ports are connected to the batteries through the transducers. The two kinds of power are coupled on the outer rotor of the EMCVT. The EMCVT can be equipped on the conventional vehicle being regarded as the CVT and it also can be equipped on the hybrid electric vehicle(HEV) as the multi-energy sources assembly. The power flows of these two kinds of applications are analysed. The back electromotive force(EMF) equations are illatively studied and so the dynamic mathematic model is theorized. In order to certify the feasibility of the above theories, three simulations are carried out in allusion to the above two kinds of mentioned applications of the EMCVT and a five speed automatic transmission(AT) vehicle. The simulation results illustrate that the efficiency of the EMCVT vehicles is higher than that of the AT vehicle owed to the optimized operation area of the engine. Hence the fuel consumption of the EMCVT vehicles is knock-down.
基金This project is supported by National Natural Science Foundation of China (No.59975053)
摘要A universal expression for the transmitted power to the flexible foundation via the finite continuous isolation system of asymmetry is derived where the concept of effective mobility for the coupled system with continuous contact points is put forward. On the basis of the theoretic calculation and analysis, effects of structure parameters of the system on the power flow transmission as well as on the isolation efficiency are fully investigated.
摘要This paper is a further study of two papers [1] and [2], which were related to Ill-Conditioned Load Flow Problems and were published by IEEE Trans. PAS. The authors of this paper have some different opinions, for example, the 11-bus system is not an ill-conditioned system. In addition, a new approach to solve Load Flow Problems, E-ψtc, is introduced. It is an explicit method;solving linear equations is not needed. It can handle very tough and very large systems. The advantage of this method has been fully proved by two examples. The authors give this new method a detailed description of how to use it to solve Load Flow Problems and successfully apply it to the 43-bus and the 11-bus systems. The authors also propose a strategy to test the reliability, and by solving gradient equations, this new method can answer if the solution exists or not.
基金supported by the Science and Technology Project of State Grid Corporation of China(No.5400-202318547A-3-2-ZN).
摘要As an effective emulator of ill-conditioned power flow,continuous Newton methods(CNMs)have been extensively investigated using explicit and implicit numerical integration algorithms.However,explicit CNMs often suffer from non-convergence due to their limited stability region,while implicit CNMs require additional iterative loops to solve nonlinear equations.To address this,we propose a semi-implicit version of CNM.We formulate the power flow equations as a set of differential algebraic equations(DAEs),and solve the DAEs with the stiffly accurate Rosenbrock type method(SARM).The proposed method succeeds the numerical robustness from the implicit CNM framework while prevents the iterative solution of nonlinear systems,hence revealing higher convergence speed and computation efficiency.We develop a novel 4-stage,3rd-order hyper-stable SARM with an embedded 2nd-order formula for adaptive step size control.This design enhances convergence through damping adjustment.Case studies on ill-conditioned systems verify the alleged performance.An algorithm extension for MATPOWER is made available on Github for benchmarking.
基金The authors acknowledge the support of Project supported by recommend international advanced agricultural science and technology plan of Ministry of Agriculture of China (Grant No. 2010-Z18), and the National Natural Science Foundation of China (Grant No. 51275249).
摘要Based on an exact CAD model of hydro-mechanical continuously variable transmission (HMCVT) gearbox which can transmit 180 horsepower, virtual prototype of the HMCVT was built. Revolution speed of shafts, gears and clutches of the HMCVT were calibrated by using results obtained by theoretical calculation and test methods. The needed power and torques of both mechanical power input shaft and hydropower input shaft were calculated by simulation. Hydraulic power distributing ratio and power flow of the system was also studied. The analysis results showed that cycle power was produced inevitably when the output shaft speed of HMCVT change smoothly during mechanical and hydraulic working state HM1 to HM4, and the instantaneous maximum cycle power was 39.5%. Then the overall transmission efficiency of HMCVT was studied, and the maximum overall efficiency of the system was about 87%. The results of the studies gave references to select suited engine and variable displacement pump for the HMCVT, and to develop rational speed control strategies for the HMCVT by changing displacement ratio of variable displacement pump.
摘要随着可再生能源渗透率不断提高,电力系统运行不确定性显著增加.为应对风电不确定性对电力系统暂态稳定造成的影响,本文引入机会约束,将新能源出力的不确定性纳入暂态稳定约束最优潮流模型中.通过将传统的暂态稳定约束预防控制转化为机会约束优化问题,提出一种基于深度西格马点过程(deep Sigma point processes,DSPP)的机会约束暂态稳定预防控制方法,并采用连续域蚁群优化(ant colony optimization for continuous domains,ACOR)算法对控制策略进行迭代更新,以确保新生成的高质量解决方案能够持续替代旧方案.本文所提出的成本最小化方法不仅执行时间较短,还能有效管理能源资源,且在平均值和标准差等统计指标上优于传统方法.同时,ACOR算法在降低电力系统燃料成本的同时,确保了较高的精度和收敛性.最后,通过在IEEE39节点系统上的仿真结果表明,该方法在经济性、收敛稳定性和计算效率方面均优于传统方法.
摘要The continuation power flow method combined with the Jacobi-Davidson method is presented to trace the critical eigenvalues for power system small signal stability analysis. The continuation power flow based on a predictor- corrector technique is applied to evaluate a continuum of steady state power flow solutions as system parameters change;meanwhile, the critical eigenvalues are found by the Jacobi-Davidson method, and thereby the trajectories of the critical eigenvalues, Hopf bifurcation and saddle node bifurcation points can also be found by the proposed method. The numerical simulations are studied in the IEEE 30-bus test system.
基金This work is supported by National Natural Science Foundation of China(No.51077042,No.51577049)Special Foundation of The doctoral program of Higher Education(No.20120094110008).
摘要As the integration of distributed generations(DGs)transforms the traditional distribution network into the active distribution network,voltage stability assessments(VSA)of transmission grid and distribution grid are not suitable to be studied separately.This paper presents a distributed continuation power flow method for VSA of global transmission and distribution grid.Two different parameterization schemes are adopted to guarantee the coherence of load growth in transmission and distribution grids.In the correction step,the boundary bus voltage,load parameter and equivalent power are communicated between the transmission and distribution control centers to realize the distributed computation of load margin.The optimal multiplier technique is used to improve the convergence of the proposed method.The three-phase unbalanced characteristic of distribution networks and the reactive capability limits of DGs are considered.Simulation results on two integrated transmission and distribution test systems show that the proposed method is effective.
基金This work is supported by the National Natural Science Foundation of China(Grant No.11774256)the Natural Science Foundation of Guangdong Province(Grant No.2018B03031104).
摘要Photoacoustic Doppler flow measurement based on continuous wave laser excitation owns the merit of clearly presenting the Doppler power spectra.Extending this technique to dual wavelengths can gain the spectral information of the flow sample extra to the flow speed information.An experimental system with two laser diodes respectively operated at 405 nm and 660 nm wavelengths is built and the flow measurement with black and red dyed polystyrene beads is performed.The measured Doppler power spectra can vividly reflect the flow speed,the flow direction,as well as the bead color.Since it is straightforward to further apply the same principle to multiple wavelengths,we can expect this type of spectroscopic photoacoustic Doppler flow measurement will be developed in the near future which will be very useful for studying the metabolism of the slowly moving red blood cell inside microvessels.