在传统的直接功率控制(Direct Power Control,简称DPC)中,无功失调导致了输入电流谐波的增加,为加强对无功功率的控制,研究了一种空间电压矢量调制(Space Vector Modulation,简称SVM)与DPC结合的控制策略,即DPC-SVM。实验结果证明,DPC-...在传统的直接功率控制(Direct Power Control,简称DPC)中,无功失调导致了输入电流谐波的增加,为加强对无功功率的控制,研究了一种空间电压矢量调制(Space Vector Modulation,简称SVM)与DPC结合的控制策略,即DPC-SVM。实验结果证明,DPC-SVM对无功和有功都有良好的控制能力,使电网的输入电流更接近于正弦波。展开更多
带蓄电池储能装置的静止同步补偿器(STATCOM/BESS)在解决快速补偿系统所需要的有功功率和无功功率、灵活平抑新能源发电引起的供电波动等问题中是非常重要的装备。直接功率控制(Direct Power Control,DPC)是瞬时功率理论的另一种表现形...带蓄电池储能装置的静止同步补偿器(STATCOM/BESS)在解决快速补偿系统所需要的有功功率和无功功率、灵活平抑新能源发电引起的供电波动等问题中是非常重要的装备。直接功率控制(Direct Power Control,DPC)是瞬时功率理论的另一种表现形式,它无需借助其他变量,对有功功率和无功功率直接进行控制。文章主要对STATCOM/BESS装置DPC控制策略和控制算法进行了理论分析,并将DPC控制策略及基于空间矢量调制的直接功率控制策略(Direct power control with space vector modulation,DPC-SVM)运用到系统中,在Matlab/Simulink中进行仿真分析。展开更多
恒频直接功率控制(constant switching frequency direct power control,CSF-DPC)具有开关频率固定、动态性能好、系统采样频率较低等优点。电网电压不平衡会在脉宽调制(pulse width modulation,PWM)型整流器交流侧产生大量谐波电流,使...恒频直接功率控制(constant switching frequency direct power control,CSF-DPC)具有开关频率固定、动态性能好、系统采样频率较低等优点。电网电压不平衡会在脉宽调制(pulse width modulation,PWM)型整流器交流侧产生大量谐波电流,使系统有功功率大幅波动,恶化系统性能。针对上述情况,提出一种新型恒频直接功率控制策略。该策略首先分离出电网电压和电流正、负序分量;然后在正、负序双旋转坐标系下计算瞬时功率与参考值之间的误差,根据误差生成整流器正、负序参考电压;合成后采用空间矢量调制(spacevector modulation,SVM)算法产生整流器电压,对功率进行补偿。该策略可有效抑制交流侧电流谐波,减小系统无功功率直流分量,稳定系统输出的有功功率,改善系统稳态性能。仿真与实验结果证明了该策略的正确性和有效性。展开更多
传统的单矢量直接功率控制SDPC(single-vector-based direct power control)以其结构简单和动态响应快等优点在双馈电机DFIG(doubly-fed induction generator)并网发电控制中得到了广泛研究,但同时具有高采样频率、变开关频率和稳态脉...传统的单矢量直接功率控制SDPC(single-vector-based direct power control)以其结构简单和动态响应快等优点在双馈电机DFIG(doubly-fed induction generator)并网发电控制中得到了广泛研究,但同时具有高采样频率、变开关频率和稳态脉动大等缺点。在传统矢量表直接功率控制的基础上,将占空比优化的思想引入双馈电机直接功率控制中,深入研究了双矢量直接功率控制,以期在取得较快动态响应的同时,减低稳态功率脉动。最后搭建了实验平台对3种直接功率控制方法的动静态性能进行了实验验证和比较,为实际应用中控制算法的选择提供了理论和实验依据。展开更多
A two-layer method based on support vector machines (SVMs) has been developed to distinguish epoxide hydrolases (EHs) from other enzymes and to classify its subfamilies using its primary protein sequences. SVM classif...A two-layer method based on support vector machines (SVMs) has been developed to distinguish epoxide hydrolases (EHs) from other enzymes and to classify its subfamilies using its primary protein sequences. SVM classifiers were built using three different feature vectors extracted from the primary sequence of EHs: the amino acid composition (AAC), the dipeptide composition (DPC), and the pseudo-amino acid composition (PAAC). Validated by 5-fold cross tests, the first layer SVM clas- sifier can differentiate EHs and non-EHs with an accuracy of 94.2% and has a Matthew’s correlation coefficient (MCC) of 0.84. Using 2-fold cross validation, PAAC-based second layer SVM can further classify EH subfamilies with an overall accuracy of 90.7% and MCC of 0.87 as compared to AAC (80.0%) and DPC (84.9%). A program called EHPred has also been developed to assist readers to recognize EHs and to classify their subfamilies using primary protein sequences with greater accuracy.展开更多
文摘在传统的直接功率控制(Direct Power Control,简称DPC)中,无功失调导致了输入电流谐波的增加,为加强对无功功率的控制,研究了一种空间电压矢量调制(Space Vector Modulation,简称SVM)与DPC结合的控制策略,即DPC-SVM。实验结果证明,DPC-SVM对无功和有功都有良好的控制能力,使电网的输入电流更接近于正弦波。
文摘带蓄电池储能装置的静止同步补偿器(STATCOM/BESS)在解决快速补偿系统所需要的有功功率和无功功率、灵活平抑新能源发电引起的供电波动等问题中是非常重要的装备。直接功率控制(Direct Power Control,DPC)是瞬时功率理论的另一种表现形式,它无需借助其他变量,对有功功率和无功功率直接进行控制。文章主要对STATCOM/BESS装置DPC控制策略和控制算法进行了理论分析,并将DPC控制策略及基于空间矢量调制的直接功率控制策略(Direct power control with space vector modulation,DPC-SVM)运用到系统中,在Matlab/Simulink中进行仿真分析。
文摘恒频直接功率控制(constant switching frequency direct power control,CSF-DPC)具有开关频率固定、动态性能好、系统采样频率较低等优点。电网电压不平衡会在脉宽调制(pulse width modulation,PWM)型整流器交流侧产生大量谐波电流,使系统有功功率大幅波动,恶化系统性能。针对上述情况,提出一种新型恒频直接功率控制策略。该策略首先分离出电网电压和电流正、负序分量;然后在正、负序双旋转坐标系下计算瞬时功率与参考值之间的误差,根据误差生成整流器正、负序参考电压;合成后采用空间矢量调制(spacevector modulation,SVM)算法产生整流器电压,对功率进行补偿。该策略可有效抑制交流侧电流谐波,减小系统无功功率直流分量,稳定系统输出的有功功率,改善系统稳态性能。仿真与实验结果证明了该策略的正确性和有效性。
文摘传统的单矢量直接功率控制SDPC(single-vector-based direct power control)以其结构简单和动态响应快等优点在双馈电机DFIG(doubly-fed induction generator)并网发电控制中得到了广泛研究,但同时具有高采样频率、变开关频率和稳态脉动大等缺点。在传统矢量表直接功率控制的基础上,将占空比优化的思想引入双馈电机直接功率控制中,深入研究了双矢量直接功率控制,以期在取得较快动态响应的同时,减低稳态功率脉动。最后搭建了实验平台对3种直接功率控制方法的动静态性能进行了实验验证和比较,为实际应用中控制算法的选择提供了理论和实验依据。
基金Project (No. 20542006) supported by the National Natural ScienceFoundation of China
文摘A two-layer method based on support vector machines (SVMs) has been developed to distinguish epoxide hydrolases (EHs) from other enzymes and to classify its subfamilies using its primary protein sequences. SVM classifiers were built using three different feature vectors extracted from the primary sequence of EHs: the amino acid composition (AAC), the dipeptide composition (DPC), and the pseudo-amino acid composition (PAAC). Validated by 5-fold cross tests, the first layer SVM clas- sifier can differentiate EHs and non-EHs with an accuracy of 94.2% and has a Matthew’s correlation coefficient (MCC) of 0.84. Using 2-fold cross validation, PAAC-based second layer SVM can further classify EH subfamilies with an overall accuracy of 90.7% and MCC of 0.87 as compared to AAC (80.0%) and DPC (84.9%). A program called EHPred has also been developed to assist readers to recognize EHs and to classify their subfamilies using primary protein sequences with greater accuracy.
