This paper discussed how to protect and control the quality of wild Chinese herbal medicine resources in nature reserves by taking Longyuwan National Forest Park within Funiu Mountain Nature Reserve as an example. Thr...This paper discussed how to protect and control the quality of wild Chinese herbal medicine resources in nature reserves by taking Longyuwan National Forest Park within Funiu Mountain Nature Reserve as an example. Through the combination of three methods including literature review, visiting and investigational studies, and field surveys, the data of investigation, collection and collation were analyzed. According to data of surveys, collection and collation, problems related to the protection of wild Chinese herbal medicine resources faced by Longyuwan Scenic Spot within Funiu Mountain Nature Reserve were also analyzed and protection strategies and quality control of wild Chinese herbal medicine resources in this nature reserve were discussed. It was expected that the results would provide important scientific references for the sustainable development, protection and quality control of wild Chinese herbal medicine resources within nature reserves.展开更多
Call admission control (CAC) and resource reservation (RR) for mobile communication are two important factors that guarantee system efficiency and quality of service (QoS) required for different services in a very sca...Call admission control (CAC) and resource reservation (RR) for mobile communication are two important factors that guarantee system efficiency and quality of service (QoS) required for different services in a very scarce resource as the radio spectrum. A new scheme was proposed which extends the concepts of resource sharing and reservations for wideband code division multiple access (WCDMA) systems with a unique feature of soft capacity. Voice and data traffic were considered. The traffic is further classified into handoff and new requests. The reservation thresholds were dynamically adjusted according to the traffic pattern and mobility prediction in order to achieve the maximum channel utilization, while guaranteeing different QoS constraints. The performance of proposed scheme was evaluated using Markov models. New call blocking probability, handoff call dropping probability, and channel utilization were used as benchmarks for the proposed scheme.展开更多
风电参与系统调频是提升新能源高占比电力系统频率安全稳定水平的关键措施之一。然而风电机组的现有调频控制策略难以适应系统多样化的功率扰动,未能充分发挥风电机组的快速频率支撑能力。建立了直驱型风电机组调频控制的通用电磁暂态模...风电参与系统调频是提升新能源高占比电力系统频率安全稳定水平的关键措施之一。然而风电机组的现有调频控制策略难以适应系统多样化的功率扰动,未能充分发挥风电机组的快速频率支撑能力。建立了直驱型风电机组调频控制的通用电磁暂态模型,并对现有调频控制策略下风电机组的动态特性进行了分析,明确了限制其调频能力的原因。在此基础上,通过建立计及风电调频的改进系统频率响应模型,实现了系统功率扰动程度的评估,并进一步提出了基于该评估结果的风电机组的主动频率支撑控制策略。该策略基于扰动发生后的最大频率变化率(rate of change of frequency, RoCoF)判断系统功率扰动程度,结合风电机组的运行模式,选择不同的调频控制组合,能够在充分发挥风电机组的主动频率支撑能力的同时,显著降低系统频率的二次跌落风险。仿真结果表明,相比于定参数调频策略和传统自适应调频策略,所提方法在不同扰动程度下的调频性能优势明显,证明了方法的有效性。展开更多
风电机组可通过超速控制提供一次调频备用(primary frequency reserve,PFR)以提升电力系统频率稳定性。但现有备用优化相关研究一方面对风电通过超速控制提供一次调频备用的决策依赖不确定性(decision dependent uncertainty,DDU)刻画...风电机组可通过超速控制提供一次调频备用(primary frequency reserve,PFR)以提升电力系统频率稳定性。但现有备用优化相关研究一方面对风电通过超速控制提供一次调频备用的决策依赖不确定性(decision dependent uncertainty,DDU)刻画尚不全面,未考虑和转速决策有关的物理约束,导致模型无法充分反应风机实际运行工况;另一方面未充分考虑感应发电机效应影响下的风机危险运行区域,可能导致系统实际运行过程中发生次同步振荡,威胁系统的安全稳定运行。针对该问题,该文分析风电一次调频备用中的决策依赖不确定性,并定义禁止转速区间,分析其对风电一次调频备用的影响。在此基础上,建立计及决策依赖不确定性和禁止转速区间的频率约束风火协同备用优化模型,并基于两个测试系统验证风电提供一次调频备用能够提升系统频率稳定性和运行经济性,以及考虑禁止转速区间的必要性。展开更多
并网光伏系统通常以最大功率模式运行,无法全面响应电网调节需求,因此需要研究功率备用控制(power reserve control,PRC)。基于最大功率点估计(maximum power point estimation,MPPE)的PRC利用光伏等效模型,通过数据拟合实现MPPE,从而...并网光伏系统通常以最大功率模式运行,无法全面响应电网调节需求,因此需要研究功率备用控制(power reserve control,PRC)。基于最大功率点估计(maximum power point estimation,MPPE)的PRC利用光伏等效模型,通过数据拟合实现MPPE,从而实现光伏功率备用。然而,随着光伏组件老化,MPPE估计误差增大,可能影响系统安全稳定运行。文中提出考虑光伏组件老化时MPPE模型参数校准的光伏系统PRC。首先提出基于麻雀搜索算法的MPPE模型参数校准方法,然后根据光伏组件老化特性和MPPE误差演变趋势,提出MPPE模型校准的改进评价指标和校准周期整定原则,最后将其应用于基于MPPE的PRC中。仿真结果表明,该方法能够实现光伏组件老化后MPPE模型参数自动校准,并且显著提高了MPPE精度,增强了PRC在实际应用中的可靠性。展开更多
基金Supported by Funding from the State Nationalities Affairs Commission(2015-GM-178)National Training Programs of Innovation and Entrepreneurship for Undergraduates(GCYS2016110001)
文摘This paper discussed how to protect and control the quality of wild Chinese herbal medicine resources in nature reserves by taking Longyuwan National Forest Park within Funiu Mountain Nature Reserve as an example. Through the combination of three methods including literature review, visiting and investigational studies, and field surveys, the data of investigation, collection and collation were analyzed. According to data of surveys, collection and collation, problems related to the protection of wild Chinese herbal medicine resources faced by Longyuwan Scenic Spot within Funiu Mountain Nature Reserve were also analyzed and protection strategies and quality control of wild Chinese herbal medicine resources in this nature reserve were discussed. It was expected that the results would provide important scientific references for the sustainable development, protection and quality control of wild Chinese herbal medicine resources within nature reserves.
文摘Call admission control (CAC) and resource reservation (RR) for mobile communication are two important factors that guarantee system efficiency and quality of service (QoS) required for different services in a very scarce resource as the radio spectrum. A new scheme was proposed which extends the concepts of resource sharing and reservations for wideband code division multiple access (WCDMA) systems with a unique feature of soft capacity. Voice and data traffic were considered. The traffic is further classified into handoff and new requests. The reservation thresholds were dynamically adjusted according to the traffic pattern and mobility prediction in order to achieve the maximum channel utilization, while guaranteeing different QoS constraints. The performance of proposed scheme was evaluated using Markov models. New call blocking probability, handoff call dropping probability, and channel utilization were used as benchmarks for the proposed scheme.
文摘风电参与系统调频是提升新能源高占比电力系统频率安全稳定水平的关键措施之一。然而风电机组的现有调频控制策略难以适应系统多样化的功率扰动,未能充分发挥风电机组的快速频率支撑能力。建立了直驱型风电机组调频控制的通用电磁暂态模型,并对现有调频控制策略下风电机组的动态特性进行了分析,明确了限制其调频能力的原因。在此基础上,通过建立计及风电调频的改进系统频率响应模型,实现了系统功率扰动程度的评估,并进一步提出了基于该评估结果的风电机组的主动频率支撑控制策略。该策略基于扰动发生后的最大频率变化率(rate of change of frequency, RoCoF)判断系统功率扰动程度,结合风电机组的运行模式,选择不同的调频控制组合,能够在充分发挥风电机组的主动频率支撑能力的同时,显著降低系统频率的二次跌落风险。仿真结果表明,相比于定参数调频策略和传统自适应调频策略,所提方法在不同扰动程度下的调频性能优势明显,证明了方法的有效性。
文摘风电机组可通过超速控制提供一次调频备用(primary frequency reserve,PFR)以提升电力系统频率稳定性。但现有备用优化相关研究一方面对风电通过超速控制提供一次调频备用的决策依赖不确定性(decision dependent uncertainty,DDU)刻画尚不全面,未考虑和转速决策有关的物理约束,导致模型无法充分反应风机实际运行工况;另一方面未充分考虑感应发电机效应影响下的风机危险运行区域,可能导致系统实际运行过程中发生次同步振荡,威胁系统的安全稳定运行。针对该问题,该文分析风电一次调频备用中的决策依赖不确定性,并定义禁止转速区间,分析其对风电一次调频备用的影响。在此基础上,建立计及决策依赖不确定性和禁止转速区间的频率约束风火协同备用优化模型,并基于两个测试系统验证风电提供一次调频备用能够提升系统频率稳定性和运行经济性,以及考虑禁止转速区间的必要性。
文摘并网光伏系统通常以最大功率模式运行,无法全面响应电网调节需求,因此需要研究功率备用控制(power reserve control,PRC)。基于最大功率点估计(maximum power point estimation,MPPE)的PRC利用光伏等效模型,通过数据拟合实现MPPE,从而实现光伏功率备用。然而,随着光伏组件老化,MPPE估计误差增大,可能影响系统安全稳定运行。文中提出考虑光伏组件老化时MPPE模型参数校准的光伏系统PRC。首先提出基于麻雀搜索算法的MPPE模型参数校准方法,然后根据光伏组件老化特性和MPPE误差演变趋势,提出MPPE模型校准的改进评价指标和校准周期整定原则,最后将其应用于基于MPPE的PRC中。仿真结果表明,该方法能够实现光伏组件老化后MPPE模型参数自动校准,并且显著提高了MPPE精度,增强了PRC在实际应用中的可靠性。
文摘针对静止同步补偿器(static synchronous compensator,STATCOM)在无功补偿以及抑制电压频繁波动等场景下的优良特性,对STATCOM的V-I输出特性进行详细分析,说明其参与电压控制的原理以及和容抗器相比具有的优越性。为了增大STATCOM的无功裕度,使之有足够的能力应对电力系统可能出现的各种扰动,提出STATCOM接入系统的各种控制模式,以及在稳态电压控制模式下的无功置换策略和远方自动电压控制(automatic voltage control,AVC)模式下的无功置换优化方法。在远方AVC模式下,以STATCOM无功置换后出力最小和容抗器动作次数最少为目标函数,将容抗器投切次数作为罚函数引入到目标函数中,并讨论罚函数系数的确定方法和合理性。结果表明,该无功置换优化模型可以满足调压的同时最大限度地提升STATCOM的无功裕度,同时可以使容抗器的动作次数最少。
