大容量链式电池储能系统(battery energy storagesystem,BESS)是解决风力发电等可再生能源发电大规模并网问题的有效手段之一。针对BESS的功率调节系统(powerconditioning system,PCS)控制策略,在α-β静止坐标系下应用比例谐振(proport...大容量链式电池储能系统(battery energy storagesystem,BESS)是解决风力发电等可再生能源发电大规模并网问题的有效手段之一。针对BESS的功率调节系统(powerconditioning system,PCS)控制策略,在α-β静止坐标系下应用比例谐振(proportional resonant,PR)调节器实现瞬时功率无静差控制;通过注入零序电压实现相簇间荷电状态(stateof charge,SOC)均衡控制,并通过在各级联单元叠加相应交流电压实现相簇内各单元SOC均衡。仿真结果表明,采用该控制策略的PCS进行瞬时功率控制时具有较快的动态响应速度和较小的稳态误差,同时能有效实现SOC均衡控制,验证了该控制策略的正确性和可行性。展开更多
当电网不对称时,PWM整流器最大运行功率会受到功率器件容量的限制而降低。该文基于瞬时功率理论分析了PWM整流器在电网不对称时的数学模型。介绍了电网不对称时两种整流器的控制策略:平衡的正序电流控制(balanced positive sequence cur...当电网不对称时,PWM整流器最大运行功率会受到功率器件容量的限制而降低。该文基于瞬时功率理论分析了PWM整流器在电网不对称时的数学模型。介绍了电网不对称时两种整流器的控制策略:平衡的正序电流控制(balanced positive sequence current control,BPSC)和瞬时有功功率控制(instantaneous active power control,IAPC)。采用BPSC策略能够扩展PWM整流器最大运行功率,但有功功率波动较大,而IAPC策略能够抑制有功功率波动,但运行功率较小。在此基础上文中提出了一种平衡正序电流和瞬时有功功率的协调控制策略(hybrid balanced positive sequence and instantaneous active power control,HBPSIAPC),从而实现PWM整流器功率扩展和有功功率波动最小。通过采用标幺值,简化了理论推导和分析过程。最后,在实验室搭建了PWM整流器的实验平台,验证了所提出控制策略的可行性。展开更多
While operators have started deploying fourth generation(4G) wireless communication systems,which could provide up to1 Gbps downlink peak data rate,the improved system capacity is still insufficient to meet the drasti...While operators have started deploying fourth generation(4G) wireless communication systems,which could provide up to1 Gbps downlink peak data rate,the improved system capacity is still insufficient to meet the drastically increasing demand of mobile users over the next decade.The main causes of the above-mentioned phenomenon include the following two aspects:1) the growth rate of the network capacity is far below that of user's demand,and 2) the relatively deterministic wireless access network(WAN) architecture in the existing systems cannot accommodate the prominent increase of mobile traffic with space-time domain dynamics.In order to address the above-mentioned challenges,we investigate the time-spatial consistency architecture for the future WAN,whilst emphasizing the critical roles of some spectral-efficient techniques such as Massive multiple-input multiple-output(MIMO),full-duplex(FD)operation and heterogeneous networks(HetNets).Furthermore,the energy efficiency(EE)of the HetNets under the proposed architecture is also evaluated,showing that the proposed user-selected uplink power control algorithm outperforms the traditional stochastic-scheduling strategy in terms of both capacity and EE in a two-tier HetNet.The other critical issues,including the tidal effect,the temporal failure owing to the instantaneously increased traffic,and the network wide load-balancing problem,etc.,are also anticipated to be addressed in the proposed architecture.(Abstract)展开更多
This paper presents a mathematical model of three-level voltage PWM rectifier,and derives a power control model from the theory of instantaneous power.In the vector-space,the influences on instantaneous power exercise...This paper presents a mathematical model of three-level voltage PWM rectifier,and derives a power control model from the theory of instantaneous power.In the vector-space,the influences on instantaneous power exercised by all the switching vectors are studied and illustrated separately,then a direct power control(DPC) scheme for three-level PWM rectifier which uses multistage band hysteresis comparator is proposed,and a novel switching table is designed.Meanwhile,the neutralpoint voltage unbalance is inhibited by selecting the redundancy switching states of small voltage vectors.Simulation and experimental results show that the proposed strategy can not only stabilize the DC bus voltage but also realize the unity power factor operation and the balance of neutral-point voltage.Moreover,the proposed method can improve the performance of the three-level rectifier.展开更多
文摘当电网不对称时,PWM整流器最大运行功率会受到功率器件容量的限制而降低。该文基于瞬时功率理论分析了PWM整流器在电网不对称时的数学模型。介绍了电网不对称时两种整流器的控制策略:平衡的正序电流控制(balanced positive sequence current control,BPSC)和瞬时有功功率控制(instantaneous active power control,IAPC)。采用BPSC策略能够扩展PWM整流器最大运行功率,但有功功率波动较大,而IAPC策略能够抑制有功功率波动,但运行功率较小。在此基础上文中提出了一种平衡正序电流和瞬时有功功率的协调控制策略(hybrid balanced positive sequence and instantaneous active power control,HBPSIAPC),从而实现PWM整流器功率扩展和有功功率波动最小。通过采用标幺值,简化了理论推导和分析过程。最后,在实验室搭建了PWM整流器的实验平台,验证了所提出控制策略的可行性。
基金supported by the key project of the National Natural Science Foundation of China(No.61431001)the 863 project No.2014AA01A701+4 种基金Program for New Century Excellent Talents in University(NECT12-0774)the open research fund of National Mobile Communications Research Laboratory Southeast University(No.2013D12)Fundamental Research Funds for the Central Universities(FRF-BD-15-012A)the Research Foundation of China Mobilethe Foundation of Beijing Engineering and Technology Center for Convergence Networks and Ubiquitous Services
文摘While operators have started deploying fourth generation(4G) wireless communication systems,which could provide up to1 Gbps downlink peak data rate,the improved system capacity is still insufficient to meet the drastically increasing demand of mobile users over the next decade.The main causes of the above-mentioned phenomenon include the following two aspects:1) the growth rate of the network capacity is far below that of user's demand,and 2) the relatively deterministic wireless access network(WAN) architecture in the existing systems cannot accommodate the prominent increase of mobile traffic with space-time domain dynamics.In order to address the above-mentioned challenges,we investigate the time-spatial consistency architecture for the future WAN,whilst emphasizing the critical roles of some spectral-efficient techniques such as Massive multiple-input multiple-output(MIMO),full-duplex(FD)operation and heterogeneous networks(HetNets).Furthermore,the energy efficiency(EE)of the HetNets under the proposed architecture is also evaluated,showing that the proposed user-selected uplink power control algorithm outperforms the traditional stochastic-scheduling strategy in terms of both capacity and EE in a two-tier HetNet.The other critical issues,including the tidal effect,the temporal failure owing to the instantaneously increased traffic,and the network wide load-balancing problem,etc.,are also anticipated to be addressed in the proposed architecture.(Abstract)
基金supported by the Key Program of National Natural Science Foundation of China (Grant No. 51037004)the National Natural Science Foundation of China (Grant No. 51077097)the Key Technologies Research and Development Program of Tianjin (Grant No.11ZCKFGX03300)
文摘This paper presents a mathematical model of three-level voltage PWM rectifier,and derives a power control model from the theory of instantaneous power.In the vector-space,the influences on instantaneous power exercised by all the switching vectors are studied and illustrated separately,then a direct power control(DPC) scheme for three-level PWM rectifier which uses multistage band hysteresis comparator is proposed,and a novel switching table is designed.Meanwhile,the neutralpoint voltage unbalance is inhibited by selecting the redundancy switching states of small voltage vectors.Simulation and experimental results show that the proposed strategy can not only stabilize the DC bus voltage but also realize the unity power factor operation and the balance of neutral-point voltage.Moreover,the proposed method can improve the performance of the three-level rectifier.
