According to the requirement of multi-parameter time and frequency measurement without frequency normalization,a different frequency synchronization theory is proposed based on Lissajous figure method and the variatio...According to the requirement of multi-parameter time and frequency measurement without frequency normalization,a different frequency synchronization theory is proposed based on Lissajous figure method and the variation lawof Lissajous figure which are used in practice teaching of frequency measurement. The theory can achieve high-precision transmission and comparison of time and frequency and precise locking and tracking of phase and frequency,improve the level of scientific research on time and frequency for postgraduate,and promote practice teaching innovation of time frequency measurement for undergraduate. Utilizing the ratio of horizontal and vertical inflection point of the Lissajous figure,the nominal frequency of the measured signal is precisely calculated.The frequency deviation between the measured frequency and its nominal frequency can be obtained by combining the turning cycle of the Lissajous figure. By observing the phase relationship between the frequency standard signal and the measured signal,the accurate measurement of the frequency is implemented. Experimental results showthat the direct measurement and comparison better than the 10-11 order of magnitude with common frequency source can be finished between any signal frequencies.The frequency measurement method based on the theory has the advantage of simple operation,quick measurement speed,small error,lownoise and high measurement precision. It plays an important role in time synchronization,communications,metrology,scientific research,educational technology practice and equipment and other fields.展开更多
高渗透率新能源波动下系统动态频率预测是实现受端网络频率安全态势感知的基础。该文提出一种基于混合量测和物理状态方程联合驱动的新能源电力系统双向树状长短期记忆网络(combined equation-of-state-driven and data-driven bi-direc...高渗透率新能源波动下系统动态频率预测是实现受端网络频率安全态势感知的基础。该文提出一种基于混合量测和物理状态方程联合驱动的新能源电力系统双向树状长短期记忆网络(combined equation-of-state-driven and data-driven bi-directional tree-struct long short term memory,CEOSD-BITREE-LSTM)动态频率预测方法。首先,引入双层多头注意力图神经网络,提出考虑同步相量测量单元(synchronous phasor measurement unit,PMU)和数据采集与监视控制系统装置(supervisory control and data acquisition,SCADA)量测差异性和时序同步性的混合量测融合策略;其次,依据PMU密集采样特性,建立计及源网荷物理联系的线性时变状态方程,刻画物理-数据空间的频率特征交互关系;然后,考虑新能源出力、负荷波动等不确定因素,结合以PMU并行搜索调频资源形成的拓扑结构,构建CEOSD-BITREE-LSTM动态频率预测模型,实现系统频率态势的高精度预测。最后,以改进新英格兰10机39节点、三区互联系统为算例,验证该文所提方法的可行性和有效性。展开更多
Micro-satellite cluster enables a whole new class of missions for communications, remote sensing, and scientific research for both civilian and military purposes. Synchronizing the time of the satellites in a cluster ...Micro-satellite cluster enables a whole new class of missions for communications, remote sensing, and scientific research for both civilian and military purposes. Synchronizing the time of the satellites in a cluster is important for both cluster sensing capabilities and its autonomous operating. However, the existing time synchronization methods are not suitable for microsatellite cluster, because it requires too many human interventions and occupies too much ground control resource. Although, data post-process may realize the equivalent time synchronization, it requires processing time and powerful computing ability on the ground, which cannot be implemented by cluster itself. In order to autonomously establish and maintain the time benchmark in a cluster, we propose a compact time difference compensation system（TDCS）, which is a kind of time control loop that dynamically adjusts the satellite reference frequency according to the time difference. Consequently, the time synchronization in the cluster can be autonomously achieved on-orbit by synchronizing the clock of other satellites to a chosen one＇s. The experimental result shows that the standard deviation of time synchronization is about 102 ps when the carrier to noise ratio（CNR） is 95 d BHz, and the standard deviation of corresponding frequency difference is approximately0.36 Hz.展开更多
We analyze the phenomena of phase group synchronization between the different nominal frequency signals and propose a new theory of the equivalent comparison between them. The exact expression of the equivalent compar...We analyze the phenomena of phase group synchronization between the different nominal frequency signals and propose a new theory of the equivalent comparison between them. The exact expression of the equivalent comparison is deduced. High resolution frequency measurement and phase comparison can be realized using this theory with the divider. For avoiding the frequency mixing, multiplication and synthesis, the system phase noise is improved and the higher resolution comparison and measurement are achieved between the different nominal frequencies by theory.展开更多
The Chinese Area Positioning System (CAPS) works without atomic clocks on the satellite, and the CAPS navigation signals transmitted on the ground may achieve the same effect as that with high-performance atomic clock...The Chinese Area Positioning System (CAPS) works without atomic clocks on the satellite, and the CAPS navigation signals transmitted on the ground may achieve the same effect as that with high-performance atomic clocks on the satellite. The primary means of achieving that effect is through the time synchronization and carrier frequency control of the CAPS navigation signals generated on the ground. In this paper the synchronization requirements of different time signals are analyzed by the formation of navigation signals, and the theories and methods of the time synchronization of the CAPS navigation signals generated on the ground are also introduced. According to the conditions of the high-precision satellite velocitymeasurement signal source, the carrier frequency and its chains of the navigation signals are constructed. CAPS velocity measurement is realized by the expected deviation of real time control to the carrier frequency, and the precision degree of this method is also analyzed. The experimental results show that the time synchronization precision of CAPS generating signals is about 0.3 ns and the precision of the velocity measurement signal source is about 4 cm/s. This proves that the theories and methods of the generating time synchronization and carrier frequency control are workable.展开更多
基金Supported by the Project of Higher Education Teaching Reform and Practice in Henan Province(2017SJGLX353)the Project of Science and Technology on Electronic Information Control Laboratory,the Science and Technology Innovation Talents in Colleges and Universities of Henan Province(16HASTIT036)+2 种基金the Educational Technology Equipment and Practical Education of Henan Province(GZS028)the National Natural Science Foundation of China(U1304618)the Key Projects of Science And Technology of Henan Province(152102210351)
文摘According to the requirement of multi-parameter time and frequency measurement without frequency normalization,a different frequency synchronization theory is proposed based on Lissajous figure method and the variation lawof Lissajous figure which are used in practice teaching of frequency measurement. The theory can achieve high-precision transmission and comparison of time and frequency and precise locking and tracking of phase and frequency,improve the level of scientific research on time and frequency for postgraduate,and promote practice teaching innovation of time frequency measurement for undergraduate. Utilizing the ratio of horizontal and vertical inflection point of the Lissajous figure,the nominal frequency of the measured signal is precisely calculated.The frequency deviation between the measured frequency and its nominal frequency can be obtained by combining the turning cycle of the Lissajous figure. By observing the phase relationship between the frequency standard signal and the measured signal,the accurate measurement of the frequency is implemented. Experimental results showthat the direct measurement and comparison better than the 10-11 order of magnitude with common frequency source can be finished between any signal frequencies.The frequency measurement method based on the theory has the advantage of simple operation,quick measurement speed,small error,lownoise and high measurement precision. It plays an important role in time synchronization,communications,metrology,scientific research,educational technology practice and equipment and other fields.
文摘高渗透率新能源波动下系统动态频率预测是实现受端网络频率安全态势感知的基础。该文提出一种基于混合量测和物理状态方程联合驱动的新能源电力系统双向树状长短期记忆网络(combined equation-of-state-driven and data-driven bi-directional tree-struct long short term memory,CEOSD-BITREE-LSTM)动态频率预测方法。首先,引入双层多头注意力图神经网络,提出考虑同步相量测量单元(synchronous phasor measurement unit,PMU)和数据采集与监视控制系统装置(supervisory control and data acquisition,SCADA)量测差异性和时序同步性的混合量测融合策略;其次,依据PMU密集采样特性,建立计及源网荷物理联系的线性时变状态方程,刻画物理-数据空间的频率特征交互关系;然后,考虑新能源出力、负荷波动等不确定因素,结合以PMU并行搜索调频资源形成的拓扑结构,构建CEOSD-BITREE-LSTM动态频率预测模型,实现系统频率态势的高精度预测。最后,以改进新英格兰10机39节点、三区互联系统为算例,验证该文所提方法的可行性和有效性。
基金supported by the National Natural Science Foundation of China(61401389)the Joint Fund of the Ministry of Education of China(6141A02033310)
文摘Micro-satellite cluster enables a whole new class of missions for communications, remote sensing, and scientific research for both civilian and military purposes. Synchronizing the time of the satellites in a cluster is important for both cluster sensing capabilities and its autonomous operating. However, the existing time synchronization methods are not suitable for microsatellite cluster, because it requires too many human interventions and occupies too much ground control resource. Although, data post-process may realize the equivalent time synchronization, it requires processing time and powerful computing ability on the ground, which cannot be implemented by cluster itself. In order to autonomously establish and maintain the time benchmark in a cluster, we propose a compact time difference compensation system（TDCS）, which is a kind of time control loop that dynamically adjusts the satellite reference frequency according to the time difference. Consequently, the time synchronization in the cluster can be autonomously achieved on-orbit by synchronizing the clock of other satellites to a chosen one＇s. The experimental result shows that the standard deviation of time synchronization is about 102 ps when the carrier to noise ratio（CNR） is 95 d BHz, and the standard deviation of corresponding frequency difference is approximately0.36 Hz.
基金supported by the National Natural Science Foundation of China(Grant Nos.10978017 and 61201288)the Fundamental Research Funds for the Central Universities,China(Grant No.JB140413)
文摘We analyze the phenomena of phase group synchronization between the different nominal frequency signals and propose a new theory of the equivalent comparison between them. The exact expression of the equivalent comparison is deduced. High resolution frequency measurement and phase comparison can be realized using this theory with the divider. For avoiding the frequency mixing, multiplication and synthesis, the system phase noise is improved and the higher resolution comparison and measurement are achieved between the different nominal frequencies by theory.
基金Supported by the Major Knowledge Innovation Programs of the Chinese Academy of Sciences (Grant No. KGCX1-21)the National High Technology Research and Development Program of China (Grant Nos. 2004AA105030 and 2006AA12Z314)+1 种基金the National Natural Science Foundation of China (Grant No. 10453001)the Major State Basic Research Development Program of China (Grant No. 2007CB815502)
文摘The Chinese Area Positioning System (CAPS) works without atomic clocks on the satellite, and the CAPS navigation signals transmitted on the ground may achieve the same effect as that with high-performance atomic clocks on the satellite. The primary means of achieving that effect is through the time synchronization and carrier frequency control of the CAPS navigation signals generated on the ground. In this paper the synchronization requirements of different time signals are analyzed by the formation of navigation signals, and the theories and methods of the time synchronization of the CAPS navigation signals generated on the ground are also introduced. According to the conditions of the high-precision satellite velocitymeasurement signal source, the carrier frequency and its chains of the navigation signals are constructed. CAPS velocity measurement is realized by the expected deviation of real time control to the carrier frequency, and the precision degree of this method is also analyzed. The experimental results show that the time synchronization precision of CAPS generating signals is about 0.3 ns and the precision of the velocity measurement signal source is about 4 cm/s. This proves that the theories and methods of the generating time synchronization and carrier frequency control are workable.
