A conceptual superconducting DC cable model is designed and its magnetic fields distribution is analyzed with Ansoft/Maxwell soft. A DC Power transmission system is also studied by using the Matlab/Simulink. With the ...A conceptual superconducting DC cable model is designed and its magnetic fields distribution is analyzed with Ansoft/Maxwell soft. A DC Power transmission system is also studied by using the Matlab/Simulink. With the DC Line and AC Ground Fault, the system losses analysis is introduced.The analysis results mainly include the magnetic fields distribution of the HTS cable model with Ansoft/Maxwell, the system loss, the DC Line and AC Ground Fault with Matlab/Simulation.展开更多
Holding the greatest power transmission capacity in China, Three Gorges power transmission and substation (T&S) project is an important landmark in the
Inter-regional transmission line fault often results in power flow transferring, tie-line overloading and system islanding. Traditional control methods such asgenerator tripping and load shedding are costly, and also ...Inter-regional transmission line fault often results in power flow transferring, tie-line overloading and system islanding. Traditional control methods such asgenerator tripping and load shedding are costly, and also have undesirable impacts on theloadside. In this paper, a new emergency power control strategy is proposed for multi-channel interconnected system by using the overload capacity of non-fault DC lines. First of all, the capacity of emergency power control can be acquired by critical transmission power of a certain tie-line for stability. Secondly, the shortest electric distance can be calculated by Dijkstra algorithm, and then the priority of emergency control of the DC lines can be obtained by the entropy weight method. When the inter-regional transmission power decreases and the effect of single DC line emergency control is poor, the multi-channel cooperative emergency control strategy is proposed to ensure the system stability. Simulation results verify the effectiveness of the method proposed.展开更多
Employing even higher voltage level to promote power transmission economy is an important subject in the program of power transmission from west to east. The influence of electro-magnetic environment of transmission p...Employing even higher voltage level to promote power transmission economy is an important subject in the program of power transmission from west to east. The influence of electro-magnetic environment of transmission project being closely related with human health and construction cost has to be seriously considered before advancing transmission voltage. This paper analyzes and discusses overseas and domestic research achievements on radio interference, audible noise, power frequency electric field, power frequency magnetic fields, DC resultant field intensity and ion stream involved in power transmission at ultra-high-voltage (UHV)AC and ± 800 kV DC or even higher voltage levels. Suggestions on limiting electro-magnetic effects and their ceiling value as well as measures to improve electro-magnetic environment are put forward.展开更多
为提高风电场交直流混合输电并网的系统性能,提出一种更加灵活的电压源换流器高压直流(voltage source converter based high voltage direct current,VSC-HVDC)控制策略。对于风电场侧电压源换流器,设计了一种新的交流电压–功角控制...为提高风电场交直流混合输电并网的系统性能,提出一种更加灵活的电压源换流器高压直流(voltage source converter based high voltage direct current,VSC-HVDC)控制策略。对于风电场侧电压源换流器,设计了一种新的交流电压–功角控制方法。对于交直流混合输电模式,该方法通过调节风电场交流母线电压与电压源换流器输出电压间的功角来实现定有功功率控制。对于纯柔性直流输电模式,风电场交流母线电压自动被调节为具有恒幅恒频的交流电压,实现了对波动风电的同步输送。该方法中输电模式的变化无需切换控制;另外,通过附加电流高通滤波器增强了对系统谐振的阻尼作用。对电网侧电压源换流器,采用一种新的直接电流矢量控制,使直流电压稳定在参考值上。运用PSCAD/EMTDC仿真软件对分别接入笼型感应发电机(squirrel cage induction generator,SCIG)风电场和双馈感应发电机(doubly fed induction generator,DFIG)风电场的交直流混合输电系统建模仿真。一系列运行条件下的仿真结果验证了控制方法的有效性与可行性。展开更多
直流电流互感器(direct-current current transformers,DCCT)是高压直流输电系统中的重要测量设备。为保证其准确可靠,DCCT投运前和停电维护时需现场校准。对于电子式DCCT现场抗干扰及数字化同步两大关键问题,该文提出电子式DCCT的校准...直流电流互感器(direct-current current transformers,DCCT)是高压直流输电系统中的重要测量设备。为保证其准确可靠,DCCT投运前和停电维护时需现场校准。对于电子式DCCT现场抗干扰及数字化同步两大关键问题,该文提出电子式DCCT的校准方法并设计一套校准系统,主要包括直流电流源、作为标准器的磁调制式直流电流比较仪(DC current comparator,DCC)和具有光纤数字同步的电子式DCCT校验仪。重点对标准器和校验仪进行了现场抗干扰分析,对于标准器现场使用时可能遇到的母线偏心和邻近通流导体干扰情况进行仿真分析,优化磁屏蔽结构,研制了DCC样机,经中国计量科学研究院校准,该DCC不确定度为5×10-6,在此基础上进行了母线偏心和邻近导体影响测试,验证了优化的屏蔽结构能够有效抵御现场干扰;为检验校准系统,采用0.2级DCCT进行了校准测试,结果表明校准系统不确定度优于5×10-4。展开更多
文摘A conceptual superconducting DC cable model is designed and its magnetic fields distribution is analyzed with Ansoft/Maxwell soft. A DC Power transmission system is also studied by using the Matlab/Simulink. With the DC Line and AC Ground Fault, the system losses analysis is introduced.The analysis results mainly include the magnetic fields distribution of the HTS cable model with Ansoft/Maxwell, the system loss, the DC Line and AC Ground Fault with Matlab/Simulation.
文摘Holding the greatest power transmission capacity in China, Three Gorges power transmission and substation (T&S) project is an important landmark in the
文摘Inter-regional transmission line fault often results in power flow transferring, tie-line overloading and system islanding. Traditional control methods such asgenerator tripping and load shedding are costly, and also have undesirable impacts on theloadside. In this paper, a new emergency power control strategy is proposed for multi-channel interconnected system by using the overload capacity of non-fault DC lines. First of all, the capacity of emergency power control can be acquired by critical transmission power of a certain tie-line for stability. Secondly, the shortest electric distance can be calculated by Dijkstra algorithm, and then the priority of emergency control of the DC lines can be obtained by the entropy weight method. When the inter-regional transmission power decreases and the effect of single DC line emergency control is poor, the multi-channel cooperative emergency control strategy is proposed to ensure the system stability. Simulation results verify the effectiveness of the method proposed.
文摘Employing even higher voltage level to promote power transmission economy is an important subject in the program of power transmission from west to east. The influence of electro-magnetic environment of transmission project being closely related with human health and construction cost has to be seriously considered before advancing transmission voltage. This paper analyzes and discusses overseas and domestic research achievements on radio interference, audible noise, power frequency electric field, power frequency magnetic fields, DC resultant field intensity and ion stream involved in power transmission at ultra-high-voltage (UHV)AC and ± 800 kV DC or even higher voltage levels. Suggestions on limiting electro-magnetic effects and their ceiling value as well as measures to improve electro-magnetic environment are put forward.
文摘为提高风电场交直流混合输电并网的系统性能,提出一种更加灵活的电压源换流器高压直流(voltage source converter based high voltage direct current,VSC-HVDC)控制策略。对于风电场侧电压源换流器,设计了一种新的交流电压–功角控制方法。对于交直流混合输电模式,该方法通过调节风电场交流母线电压与电压源换流器输出电压间的功角来实现定有功功率控制。对于纯柔性直流输电模式,风电场交流母线电压自动被调节为具有恒幅恒频的交流电压,实现了对波动风电的同步输送。该方法中输电模式的变化无需切换控制;另外,通过附加电流高通滤波器增强了对系统谐振的阻尼作用。对电网侧电压源换流器,采用一种新的直接电流矢量控制,使直流电压稳定在参考值上。运用PSCAD/EMTDC仿真软件对分别接入笼型感应发电机(squirrel cage induction generator,SCIG)风电场和双馈感应发电机(doubly fed induction generator,DFIG)风电场的交直流混合输电系统建模仿真。一系列运行条件下的仿真结果验证了控制方法的有效性与可行性。
文摘直流电流互感器(direct-current current transformers,DCCT)是高压直流输电系统中的重要测量设备。为保证其准确可靠,DCCT投运前和停电维护时需现场校准。对于电子式DCCT现场抗干扰及数字化同步两大关键问题,该文提出电子式DCCT的校准方法并设计一套校准系统,主要包括直流电流源、作为标准器的磁调制式直流电流比较仪(DC current comparator,DCC)和具有光纤数字同步的电子式DCCT校验仪。重点对标准器和校验仪进行了现场抗干扰分析,对于标准器现场使用时可能遇到的母线偏心和邻近通流导体干扰情况进行仿真分析,优化磁屏蔽结构,研制了DCC样机,经中国计量科学研究院校准,该DCC不确定度为5×10-6,在此基础上进行了母线偏心和邻近导体影响测试,验证了优化的屏蔽结构能够有效抵御现场干扰;为检验校准系统,采用0.2级DCCT进行了校准测试,结果表明校准系统不确定度优于5×10-4。
