We demonstrate a novel and stable frequency transfer scheme over ground-to-satellite link based on real-time carrier-phase detection and compensation.We performed a zero-baseline measurement with the designed system,a...We demonstrate a novel and stable frequency transfer scheme over ground-to-satellite link based on real-time carrier-phase detection and compensation.We performed a zero-baseline measurement with the designed system,an uninterrupted frequency standard signal is recovered in the reception station without additional post-correction of delay error caused in the route,which is because the phase error of the entire route is tracked and compensated continuously in real-time.To achieve this goal,we employed two carriers in the system and the differential signal is transferred in order to eliminate the instability results from the local oscillator at the satellite transponder as well as the common-mode noise induced in the transfer route and microwave components.The stability of 3×10^(-16) with an integration time of 1 day was achieved and the time fluctuation during one day was measured to be about±20 ps.Error sources and possible solutions are discussed.Our zero-baseline method shows a promising result for real-time satellite-based time and frequency transfer and deserves further research to find whether it works between long-baseline stations.展开更多
Global navigation satellite system(GNSS)carrier phase observations are two orders of higher accuracy than pseudo-range observations,and they are less affected by multipath besides.As a result,the time transfer accurac...Global navigation satellite system(GNSS)carrier phase observations are two orders of higher accuracy than pseudo-range observations,and they are less affected by multipath besides.As a result,the time transfer accuracy can reach 0.1 ns,and the frequency transfer stability can reach 1×10^-15 with carrier phase(CP)method,therefore CP method is considered the most accurate and promising time transfer technology.The focus of this paper is to present a comprehensive summary of CP method,with specific attention directed toward day-boundary clock jump,ambiguity resolution(AR),multi-system time transfer and real-time time transfer.Day-boundary clock jump is essentially caused by pseudo-range noise.Several approaches were proposed to solve the problem,such as continuously processing strategy,sliding batch and bidirectional filtering methods which were compared in this study.Additionally,researches on AR in CP method were introduced.Many scholars attempted to fix the single-difference ambiguities to improve the time transfer result,however,owing to the uncalibrated phase delay(UPD)was not considered,the current studies on AR in CP method were still immature.Moreover,because four GNSS systems could be used for time-transfer currently,which was helpful to increase the accuracy and reliability,the researches on multi-system time transfer were reviewed.What’s more,real-time time transfer attracted more attention nowadays,the preliminary research results were presented.展开更多
随着海上风电、光伏等新能源的大规模建设,产生了直流输电、交直流互联和储能的应用需求。目前储能技术的研究和应用主要集中于交流储能领域。模块化多电平电池储能系统(modular multilevel converter based battery energy storage sys...随着海上风电、光伏等新能源的大规模建设,产生了直流输电、交直流互联和储能的应用需求。目前储能技术的研究和应用主要集中于交流储能领域。模块化多电平电池储能系统(modular multilevel converter based battery energy storage system,MMC-BESS)虽然在交直流互联的同时,实现了储能的功能,但电池中流过的工频、二倍频等脉动电流成分对电池寿命有潜在影响,且传统的模块化多电平(modular multilevel converter,MMC)换流站的改造成本高。本工作提出的直流直挂储能装置将换流和储能分离,电池电流仅为直流和高频脉动成分,工况对电池友好,且直流直挂储能系统需要电池单体数量仅为MMC-BESS的1/6,成本低。对直流直挂储能装置的拓扑结构及工作原理进行分析;对级联子模块的数量和参数进行设计;基于载波移相调制,推导直流纹波电流,进而对并网电感参数进行设计;建立直流直挂储能装置的数学模型,推导控制模型,根据控制框图进行功率控制。最后,通过仿真和样机实验,验证该半桥拓扑级联型直流直挂储能装置设计的可行性及正确性。实验证明,该设计和控制方法效果良好,对高压大容量直流直挂储能装置的设计有一定参考价值。展开更多
基金Project supported by the National Key Research and Development Program of China (Grant No. 2016YFA0302101)the Initiative Program of State Key Laboratory of Precision Measurement Technology and Instruments
文摘We demonstrate a novel and stable frequency transfer scheme over ground-to-satellite link based on real-time carrier-phase detection and compensation.We performed a zero-baseline measurement with the designed system,an uninterrupted frequency standard signal is recovered in the reception station without additional post-correction of delay error caused in the route,which is because the phase error of the entire route is tracked and compensated continuously in real-time.To achieve this goal,we employed two carriers in the system and the differential signal is transferred in order to eliminate the instability results from the local oscillator at the satellite transponder as well as the common-mode noise induced in the transfer route and microwave components.The stability of 3×10^(-16) with an integration time of 1 day was achieved and the time fluctuation during one day was measured to be about±20 ps.Error sources and possible solutions are discussed.Our zero-baseline method shows a promising result for real-time satellite-based time and frequency transfer and deserves further research to find whether it works between long-baseline stations.
基金supported in part by the National Key Research and Development Program of China(Grant No.2016YFB0800401)in part by the National Natural Science Foundation of China(Grants Nos.61621003,61532020&11472290)。
文摘Global navigation satellite system(GNSS)carrier phase observations are two orders of higher accuracy than pseudo-range observations,and they are less affected by multipath besides.As a result,the time transfer accuracy can reach 0.1 ns,and the frequency transfer stability can reach 1×10^-15 with carrier phase(CP)method,therefore CP method is considered the most accurate and promising time transfer technology.The focus of this paper is to present a comprehensive summary of CP method,with specific attention directed toward day-boundary clock jump,ambiguity resolution(AR),multi-system time transfer and real-time time transfer.Day-boundary clock jump is essentially caused by pseudo-range noise.Several approaches were proposed to solve the problem,such as continuously processing strategy,sliding batch and bidirectional filtering methods which were compared in this study.Additionally,researches on AR in CP method were introduced.Many scholars attempted to fix the single-difference ambiguities to improve the time transfer result,however,owing to the uncalibrated phase delay(UPD)was not considered,the current studies on AR in CP method were still immature.Moreover,because four GNSS systems could be used for time-transfer currently,which was helpful to increase the accuracy and reliability,the researches on multi-system time transfer were reviewed.What’s more,real-time time transfer attracted more attention nowadays,the preliminary research results were presented.
文摘随着海上风电、光伏等新能源的大规模建设,产生了直流输电、交直流互联和储能的应用需求。目前储能技术的研究和应用主要集中于交流储能领域。模块化多电平电池储能系统(modular multilevel converter based battery energy storage system,MMC-BESS)虽然在交直流互联的同时,实现了储能的功能,但电池中流过的工频、二倍频等脉动电流成分对电池寿命有潜在影响,且传统的模块化多电平(modular multilevel converter,MMC)换流站的改造成本高。本工作提出的直流直挂储能装置将换流和储能分离,电池电流仅为直流和高频脉动成分,工况对电池友好,且直流直挂储能系统需要电池单体数量仅为MMC-BESS的1/6,成本低。对直流直挂储能装置的拓扑结构及工作原理进行分析;对级联子模块的数量和参数进行设计;基于载波移相调制,推导直流纹波电流,进而对并网电感参数进行设计;建立直流直挂储能装置的数学模型,推导控制模型,根据控制框图进行功率控制。最后,通过仿真和样机实验,验证该半桥拓扑级联型直流直挂储能装置设计的可行性及正确性。实验证明,该设计和控制方法效果良好,对高压大容量直流直挂储能装置的设计有一定参考价值。
