The low-frequency oscillation(LFO)has occurred in the train-network system due to the introduction of the power electronics of the trains.The modeling and analyzing method in current researches based on electrified ra...The low-frequency oscillation(LFO)has occurred in the train-network system due to the introduction of the power electronics of the trains.The modeling and analyzing method in current researches based on electrified railway unilateral power supply system are not suitable for the LFO analysis in a bilateral power supply system,where the trains are supplied by two traction substations.In this work,based on the single-input and single-output impedance model of China CRH5 trains,the node admittance matrices of the train-network system both in unilateral and bilateral power supply modes are established,including three-phase power grid,traction transformers and traction network.Then the modal analysis is used to study the oscillation modes and propagation characteristics of the unilateral and bilateral power supply systems.Moreover,the influence of the equivalent inductance of the power grid,the length of the transmission line,and the length of the traction network are analyzed on the critical oscillation mode of the bilateral power supply system.Finally,the theoretical analysis results are verified by the time-domain simulation model in MATLAB/Simulink.展开更多
With the increasing integration of new energy generation into the power system and the massive withdrawal of traditional fossil fuel generation,the power system is faced with a large number of stability problems.The p...With the increasing integration of new energy generation into the power system and the massive withdrawal of traditional fossil fuel generation,the power system is faced with a large number of stability problems.The phenomenon of low-frequency oscillation caused by lack of damping and moment of inertia is worth studying.In recent years,virtual synchronous generator(VSG)technique has been developed rapidly because it can provide considerable damping and moment of inertia.While improving the stability of the system,it also inevitably causes the problem of active power oscillation,especially the low mutual damping between the VSG and the power grid will make the oscillation more severe.The traditional time-domain state-space method cannot reflect the interaction among state variables and study the interaction between different nodes and branches of the power grid.In this paper,a frequency-domain method for analyzing low-frequency oscillations considering VSG parameter coupling is proposed.First,based on the rotor motion equation of the synchronous generator(SG),a secondorder VSG model and linearized power-frequency control loop model are established.Then,the differences and connections between the coupling of key VSG parameters and low-frequency oscillation characteristics are studied through frequency domain analysis.The path and influencemechanism of a VSG during low-frequency power grid oscillations are illustrated.Finally,the correctness of the theoretical analysis model is verified by simulation.展开更多
近年来,由极端事件导致的大停电事故给用户的生产生活带来巨大挑战。为解决不同用户对配电网灾后应急供电需求的差异性问题,提出一种面向极端事件的配电网差异化韧性供电服务及其定价方法。首先,基于电网-交通网融合系统提出考虑移动储...近年来,由极端事件导致的大停电事故给用户的生产生活带来巨大挑战。为解决不同用户对配电网灾后应急供电需求的差异性问题,提出一种面向极端事件的配电网差异化韧性供电服务及其定价方法。首先,基于电网-交通网融合系统提出考虑移动储能(mobile energy storage system,MESS)规划与调度的配电网韧性提升方法。然后,基于用户差异化的灾后供电需求设计多种韧性供电等级下的服务定价菜单。最后,为将韧性供电服务的提供与用户需求相匹配,构建韧性供电服务提供与定价双层模型,上层配电网运营商(distribution system operator,DSO)提供差异化的韧性供电服务并设计定价菜单,下层用户结合服务成本与效益订购最佳的韧性供电服务等级。改进混沌模拟退火粒子群算法(chaoticsimulated annealing particle swarm optimization,CSAPSO),结合gurobi求解器迭代寻找模型的均衡解。算例分析表明,所提方法可有效权衡DSO与用户的效益,满足了用户差异化的灾后供电需求,实现双赢。展开更多
An extremely low power voltage reference without resistors is presented for power-aware ASICs. In order to reduce the power dissipation, an Oguey current reference source is used to reduce the static current; a cascod...An extremely low power voltage reference without resistors is presented for power-aware ASICs. In order to reduce the power dissipation, an Oguey current reference source is used to reduce the static current; a cascode current mirror is used to increase the power supply rejection ratio （PSRR） and reduce the line sensitivity of the circuit. The voltage reference is fabricated in SMIC 0.18μm CMOS process. The measured results for the voltage reference demonstrate that the temperature coefficient of the voltage is 66 ppm/℃ in a range from 25 to 100 ℃. The line sensitivity is 0.9% in a supply voltage range of 1.8 to 3,3 V, and PSRR is -49 dB at 100 Hz. The power dissipation is 200 nW. The chip area is 0.01 mm2. The circuit can be used as an elementary circuit block for power-aware ASICs.展开更多
基金This work was supported by the Applied Basic Research Program of Science and Technology Plan Project of Sichuan Province of China(No.2020YJ0252).
文摘The low-frequency oscillation(LFO)has occurred in the train-network system due to the introduction of the power electronics of the trains.The modeling and analyzing method in current researches based on electrified railway unilateral power supply system are not suitable for the LFO analysis in a bilateral power supply system,where the trains are supplied by two traction substations.In this work,based on the single-input and single-output impedance model of China CRH5 trains,the node admittance matrices of the train-network system both in unilateral and bilateral power supply modes are established,including three-phase power grid,traction transformers and traction network.Then the modal analysis is used to study the oscillation modes and propagation characteristics of the unilateral and bilateral power supply systems.Moreover,the influence of the equivalent inductance of the power grid,the length of the transmission line,and the length of the traction network are analyzed on the critical oscillation mode of the bilateral power supply system.Finally,the theoretical analysis results are verified by the time-domain simulation model in MATLAB/Simulink.
基金supported by Science and Technology Project of State Grid Liaoning Electric Power Supply Co.,Ltd.(2021YF-82).
文摘With the increasing integration of new energy generation into the power system and the massive withdrawal of traditional fossil fuel generation,the power system is faced with a large number of stability problems.The phenomenon of low-frequency oscillation caused by lack of damping and moment of inertia is worth studying.In recent years,virtual synchronous generator(VSG)technique has been developed rapidly because it can provide considerable damping and moment of inertia.While improving the stability of the system,it also inevitably causes the problem of active power oscillation,especially the low mutual damping between the VSG and the power grid will make the oscillation more severe.The traditional time-domain state-space method cannot reflect the interaction among state variables and study the interaction between different nodes and branches of the power grid.In this paper,a frequency-domain method for analyzing low-frequency oscillations considering VSG parameter coupling is proposed.First,based on the rotor motion equation of the synchronous generator(SG),a secondorder VSG model and linearized power-frequency control loop model are established.Then,the differences and connections between the coupling of key VSG parameters and low-frequency oscillation characteristics are studied through frequency domain analysis.The path and influencemechanism of a VSG during low-frequency power grid oscillations are illustrated.Finally,the correctness of the theoretical analysis model is verified by simulation.
文摘近年来,由极端事件导致的大停电事故给用户的生产生活带来巨大挑战。为解决不同用户对配电网灾后应急供电需求的差异性问题,提出一种面向极端事件的配电网差异化韧性供电服务及其定价方法。首先,基于电网-交通网融合系统提出考虑移动储能(mobile energy storage system,MESS)规划与调度的配电网韧性提升方法。然后,基于用户差异化的灾后供电需求设计多种韧性供电等级下的服务定价菜单。最后,为将韧性供电服务的提供与用户需求相匹配,构建韧性供电服务提供与定价双层模型,上层配电网运营商(distribution system operator,DSO)提供差异化的韧性供电服务并设计定价菜单,下层用户结合服务成本与效益订购最佳的韧性供电服务等级。改进混沌模拟退火粒子群算法(chaoticsimulated annealing particle swarm optimization,CSAPSO),结合gurobi求解器迭代寻找模型的均衡解。算例分析表明,所提方法可有效权衡DSO与用户的效益,满足了用户差异化的灾后供电需求,实现双赢。
基金Project supported by the National Natural Science Foundation of China(Nos.61161003,61264001,61166004)the Guangxi Natural Science Foundation(No.2013GXNSFAA019333)
文摘An extremely low power voltage reference without resistors is presented for power-aware ASICs. In order to reduce the power dissipation, an Oguey current reference source is used to reduce the static current; a cascode current mirror is used to increase the power supply rejection ratio （PSRR） and reduce the line sensitivity of the circuit. The voltage reference is fabricated in SMIC 0.18μm CMOS process. The measured results for the voltage reference demonstrate that the temperature coefficient of the voltage is 66 ppm/℃ in a range from 25 to 100 ℃. The line sensitivity is 0.9% in a supply voltage range of 1.8 to 3,3 V, and PSRR is -49 dB at 100 Hz. The power dissipation is 200 nW. The chip area is 0.01 mm2. The circuit can be used as an elementary circuit block for power-aware ASICs.
