针对高渗透可再生能源接入的交直流混合配电网经济性和灵活调节性不足的问题,提出一种配合降压变压器(step down transformer,SDT)和电压源型变换器(voltage source converter,VSC)调压策略的含混合储能系统(hybrid energy storage syst...针对高渗透可再生能源接入的交直流混合配电网经济性和灵活调节性不足的问题,提出一种配合降压变压器(step down transformer,SDT)和电压源型变换器(voltage source converter,VSC)调压策略的含混合储能系统(hybrid energy storage system,HESS)交直流配电网日级别经济运行优化方法。首先,基于有功/无功-电压综合灵敏度对配电网进行分区,确定HESS的接入容量与位置;其次,基于希尔伯特-黄变换(Hilbert-Huang transform,HHT)原理对由锂电池和超级电容构成的HESS进行功率分配;然后,建立了计及HESS全生命周期的运行成本和主网购电成本的交直流混流配电网日级别经济运行优化模型;最后,对该典型二阶锥规划问题进行求解。改进IEEE33节点交直流混合配电网仿真实验表明:在合理选址定容基础上,HESS在平抑系统高频功率信号及经济性上优势明显;HESS联合SDT及VSC电压控制,可以有效降低HESS运行中出现的电压偏离程度,减小了电压约束对HESS充放电过程的影响,并进一步提升了含储能配电网经济运行能力及电压稳定性。展开更多
To solve the low power density issue of hybrid electric vehicular batteries, a combination of batteries and ultracapacitors (UCs) could be a solution. The high power density feature of UCs can improve the performance ...To solve the low power density issue of hybrid electric vehicular batteries, a combination of batteries and ultracapacitors (UCs) could be a solution. The high power density feature of UCs can improve the performance of battery/UC hybrid energy storage systems (HESSs). This paper presents a parallel hybrid electric vehicle (HEV) equipped with an internal combus- tion engine and an HESS. An advanced energy management strategy (EMS), mainly based on fuzzy logic, is proposed to improve the fuel economy of the HEV and the endurance of the HESS. The EMS is capable of determining the ideal distribution of output power among the internal combustion engine, battery, and UC according to the propelling power or regenerative braking power of the vehicle. To validate the effectiveness of the EMS, numerical simulation and experimental validations are carried out. The results indicate that EMS can effectively control the power sources to work within their respective efficient areas. The battery load can be mitigated and prolonged battery life can be expected. The electrical energy consumption in the HESS is reduced by 3.91% compared with that in the battery only system. Fuel consumption of the HEV is reduced by 24.3% compared with that of the same class conventional vehicles under Economic Commission of Europe driving cycle.展开更多
To address the impact of wind-power fluctuations on the stability of power systems,we propose a comprehensive approach that integrates multiple strategies and methods to enhance the efficiency and reliability of a sys...To address the impact of wind-power fluctuations on the stability of power systems,we propose a comprehensive approach that integrates multiple strategies and methods to enhance the efficiency and reliability of a system.First,we employ a strategy that restricts long-and short-term power output deviations to smoothen wind power fluctuations in real time.Second,we adopt the sliding window instantaneous complete ensemble empirical mode decomposition with adaptive noise(SW-ICEEMDAN)strategy to achieve real-time decomposition of the energy storage power,facilitating internal power distribution within the hybrid energy storage system.Finally,we introduce a rule-based multi-fuzzy control strategy for the secondary adjustment of the initial power allocation commands for different energy storage components.Through simulation validation,we demonstrate that the proposed comprehensive control strategy can smoothen wind power fluctuations in real time and decompose energy storage power.Compared with traditional empirical mode decomposition(EMD),ensemble empirical mode decomposition(EEMD),and complete ensemble empirical mode decomposition with adaptive noise(CEEMDAN)decomposition strategies,the configuration of the energy storage system under the SW-ICEEMDAN control strategy is more optimal.Additionally,the state-of-charge of energy storage components fluctuates within a reasonable range,enhancing the stability of the power system and ensuring the secure operation of the energy storage system.展开更多
We introduce a new interpretation and quantitative method for computerized diplopia test. By comparing this new method to the Hess screen test, we validate its applicability among 304 patients with ocular motor nerve ...We introduce a new interpretation and quantitative method for computerized diplopia test. By comparing this new method to the Hess screen test, we validate its applicability among 304 patients with ocular motor nerve palsy. This new method shows great assistant value as the Hess screen test in making accurate diagnosis and quantitative evaluation the severity of diplopia. Furthermore, it is more convenient and suitable for daily clinical use.展开更多
文摘针对高渗透可再生能源接入的交直流混合配电网经济性和灵活调节性不足的问题,提出一种配合降压变压器(step down transformer,SDT)和电压源型变换器(voltage source converter,VSC)调压策略的含混合储能系统(hybrid energy storage system,HESS)交直流配电网日级别经济运行优化方法。首先,基于有功/无功-电压综合灵敏度对配电网进行分区,确定HESS的接入容量与位置;其次,基于希尔伯特-黄变换(Hilbert-Huang transform,HHT)原理对由锂电池和超级电容构成的HESS进行功率分配;然后,建立了计及HESS全生命周期的运行成本和主网购电成本的交直流混流配电网日级别经济运行优化模型;最后,对该典型二阶锥规划问题进行求解。改进IEEE33节点交直流混合配电网仿真实验表明:在合理选址定容基础上,HESS在平抑系统高频功率信号及经济性上优势明显;HESS联合SDT及VSC电压控制,可以有效降低HESS运行中出现的电压偏离程度,减小了电压约束对HESS充放电过程的影响,并进一步提升了含储能配电网经济运行能力及电压稳定性。
基金Project (No. RD-07-267) supported by the General Motors
文摘To solve the low power density issue of hybrid electric vehicular batteries, a combination of batteries and ultracapacitors (UCs) could be a solution. The high power density feature of UCs can improve the performance of battery/UC hybrid energy storage systems (HESSs). This paper presents a parallel hybrid electric vehicle (HEV) equipped with an internal combus- tion engine and an HESS. An advanced energy management strategy (EMS), mainly based on fuzzy logic, is proposed to improve the fuel economy of the HEV and the endurance of the HESS. The EMS is capable of determining the ideal distribution of output power among the internal combustion engine, battery, and UC according to the propelling power or regenerative braking power of the vehicle. To validate the effectiveness of the EMS, numerical simulation and experimental validations are carried out. The results indicate that EMS can effectively control the power sources to work within their respective efficient areas. The battery load can be mitigated and prolonged battery life can be expected. The electrical energy consumption in the HESS is reduced by 3.91% compared with that in the battery only system. Fuel consumption of the HEV is reduced by 24.3% compared with that of the same class conventional vehicles under Economic Commission of Europe driving cycle.
基金supported by the National Natural Science Foundation of China(Grant No.51677058)。
文摘To address the impact of wind-power fluctuations on the stability of power systems,we propose a comprehensive approach that integrates multiple strategies and methods to enhance the efficiency and reliability of a system.First,we employ a strategy that restricts long-and short-term power output deviations to smoothen wind power fluctuations in real time.Second,we adopt the sliding window instantaneous complete ensemble empirical mode decomposition with adaptive noise(SW-ICEEMDAN)strategy to achieve real-time decomposition of the energy storage power,facilitating internal power distribution within the hybrid energy storage system.Finally,we introduce a rule-based multi-fuzzy control strategy for the secondary adjustment of the initial power allocation commands for different energy storage components.Through simulation validation,we demonstrate that the proposed comprehensive control strategy can smoothen wind power fluctuations in real time and decompose energy storage power.Compared with traditional empirical mode decomposition(EMD),ensemble empirical mode decomposition(EEMD),and complete ensemble empirical mode decomposition with adaptive noise(CEEMDAN)decomposition strategies,the configuration of the energy storage system under the SW-ICEEMDAN control strategy is more optimal.Additionally,the state-of-charge of energy storage components fluctuates within a reasonable range,enhancing the stability of the power system and ensuring the secure operation of the energy storage system.
文摘We introduce a new interpretation and quantitative method for computerized diplopia test. By comparing this new method to the Hess screen test, we validate its applicability among 304 patients with ocular motor nerve palsy. This new method shows great assistant value as the Hess screen test in making accurate diagnosis and quantitative evaluation the severity of diplopia. Furthermore, it is more convenient and suitable for daily clinical use.
