The intense application of Voltage Source Converter based HVDC interconnections and grids will result in a hybrid AC-HVDC-system. The operation of such a system becomes complex regarding system security and system ope...The intense application of Voltage Source Converter based HVDC interconnections and grids will result in a hybrid AC-HVDC-system. The operation of such a system becomes complex regarding system security and system operation. This paper describes major challenges and proposes potential solutions, including a combined security assessment, preventive optimization and curative actions. A coordination of both systems enables an efficient application of existing transport capacity.展开更多
HVDC (High Voltage Direct Current) systems are increasingly being applied to improve power system operation and controllability. However, inappropriate setting of HVDC controller may have a detriment effect on the sys...HVDC (High Voltage Direct Current) systems are increasingly being applied to improve power system operation and controllability. However, inappropriate setting of HVDC controller may have a detriment effect on the system performance. Generally, PSS (Power System Stabilizer) is known as a simple concept, easy to perform, and computationally effective to enhance damping of power system oscillations through excitation control of synchronous generator. This paper examines the effectiveness of the PSS to enhance the dynamic performance of AC-DC power systems and to compensate the negative damping of HVDC system. The dynamic performance is evaluated by examining the system response to various disturbances. In order to ensure the reliability of the simulation test results as well as the performance of the PSS, detailed HVDC modeling is adopted using SimPowerSystems toolbox in the MATLAB, and some important conclusions are drawn.展开更多
[目的]现有换流站无功补偿方案下,调相机仅提供暂态无功支撑,交流滤波器承担稳态无功补偿与调整任务,两者间缺少协调方案,经济性不足。[方法]在保证调相机动态特性的基础上,基于直流送、受端系统运行特性,首先提出以调相机置换部分交流...[目的]现有换流站无功补偿方案下,调相机仅提供暂态无功支撑,交流滤波器承担稳态无功补偿与调整任务,两者间缺少协调方案,经济性不足。[方法]在保证调相机动态特性的基础上,基于直流送、受端系统运行特性,首先提出以调相机置换部分交流滤波器容量,两者共同参与稳态无功补偿的换流站无功优化方案。随后按照动作顺序先后提出换流站双层无功调整策略。第一层无功调整由调相机承担,通过在稳态运行范围内调节出力实现。第二层无功调节在第一层无功调整后启动,逐组投切交流滤波器进行无功调整,直至达到换流站无功调整要求。最后,在PSCAD中搭建LCC-HVDC(Line-Commutated Converter High Voltage Direct Current,LCC高压直流输电)系统仿真模型进行仿真验证。[结果]仿真结果表明文章提出的换流站无功补偿方案和双层无功调整策略能优化换流站交流滤波器配置组数,减少换流站交流滤波器投切频次。[结论]所提方案实现了对现有LCC-HVDC换流站无功补偿方案和无功调整策略的优化。展开更多
现有低压限流环节(voltage dependent current order limitation,VDCOL)使得高压直流系统的有功和无功强耦合,不能在交流故障持续及恢复过程中充分利用换流站自身的无功支撑能力来改善其恢复性能。该文以CIGRE HVDC标准测试模型与贵广...现有低压限流环节(voltage dependent current order limitation,VDCOL)使得高压直流系统的有功和无功强耦合,不能在交流故障持续及恢复过程中充分利用换流站自身的无功支撑能力来改善其恢复性能。该文以CIGRE HVDC标准测试模型与贵广Ⅱ工程模型作为算例,对两种模型交流故障下的直流电流及无功功率可运行范围进行了分析计算,并在PSCAD/EMTDC仿真程序中进行了验证;接着,对VDCOL的外特性进行了分析,结果表明其输出的直流电流指令不在所计算的可运行范围内;最后,采用了一种替换VDCOL的无功控制策略,该策略不仅能保证故障下直流两侧的控制指令位于可运行范围内,也能改善高压直流系统的故障恢复性能。展开更多
针对柔性直流输电系统常规直流电压波动抑制算法中存在的缺陷,提出一种适用于模块化多电平换流器型高压直流输电系统(modular multilevel converter based high voltage direct current,MMC-HVDC)的直流电压波动抑制方法。该方法利用MM...针对柔性直流输电系统常规直流电压波动抑制算法中存在的缺陷,提出一种适用于模块化多电平换流器型高压直流输电系统(modular multilevel converter based high voltage direct current,MMC-HVDC)的直流电压波动抑制方法。该方法利用MMC特有的"储能"特性,在交流系统不对称时,控制MMC交、直流侧瞬时有功功率不再平衡,从而实现MMC交流侧电流依然保持对称运行,同时直流侧电压、电流和功率保持为恒定。为了实现上述控制功能与目标,建立三相交流系统不对称时MMC直流回路的模型,设计0坐标系下以比例谐振调节器为基础的控制策略,且探讨MMC-HVDC中的协调控制问题。最后,搭建71电平背靠背MMC-HVDC系统模型进行数字仿真,结果验证了所提控制方法的有效性。展开更多
文摘The intense application of Voltage Source Converter based HVDC interconnections and grids will result in a hybrid AC-HVDC-system. The operation of such a system becomes complex regarding system security and system operation. This paper describes major challenges and proposes potential solutions, including a combined security assessment, preventive optimization and curative actions. A coordination of both systems enables an efficient application of existing transport capacity.
文摘HVDC (High Voltage Direct Current) systems are increasingly being applied to improve power system operation and controllability. However, inappropriate setting of HVDC controller may have a detriment effect on the system performance. Generally, PSS (Power System Stabilizer) is known as a simple concept, easy to perform, and computationally effective to enhance damping of power system oscillations through excitation control of synchronous generator. This paper examines the effectiveness of the PSS to enhance the dynamic performance of AC-DC power systems and to compensate the negative damping of HVDC system. The dynamic performance is evaluated by examining the system response to various disturbances. In order to ensure the reliability of the simulation test results as well as the performance of the PSS, detailed HVDC modeling is adopted using SimPowerSystems toolbox in the MATLAB, and some important conclusions are drawn.
文摘[目的]现有换流站无功补偿方案下,调相机仅提供暂态无功支撑,交流滤波器承担稳态无功补偿与调整任务,两者间缺少协调方案,经济性不足。[方法]在保证调相机动态特性的基础上,基于直流送、受端系统运行特性,首先提出以调相机置换部分交流滤波器容量,两者共同参与稳态无功补偿的换流站无功优化方案。随后按照动作顺序先后提出换流站双层无功调整策略。第一层无功调整由调相机承担,通过在稳态运行范围内调节出力实现。第二层无功调节在第一层无功调整后启动,逐组投切交流滤波器进行无功调整,直至达到换流站无功调整要求。最后,在PSCAD中搭建LCC-HVDC(Line-Commutated Converter High Voltage Direct Current,LCC高压直流输电)系统仿真模型进行仿真验证。[结果]仿真结果表明文章提出的换流站无功补偿方案和双层无功调整策略能优化换流站交流滤波器配置组数,减少换流站交流滤波器投切频次。[结论]所提方案实现了对现有LCC-HVDC换流站无功补偿方案和无功调整策略的优化。
文摘现有低压限流环节(voltage dependent current order limitation,VDCOL)使得高压直流系统的有功和无功强耦合,不能在交流故障持续及恢复过程中充分利用换流站自身的无功支撑能力来改善其恢复性能。该文以CIGRE HVDC标准测试模型与贵广Ⅱ工程模型作为算例,对两种模型交流故障下的直流电流及无功功率可运行范围进行了分析计算,并在PSCAD/EMTDC仿真程序中进行了验证;接着,对VDCOL的外特性进行了分析,结果表明其输出的直流电流指令不在所计算的可运行范围内;最后,采用了一种替换VDCOL的无功控制策略,该策略不仅能保证故障下直流两侧的控制指令位于可运行范围内,也能改善高压直流系统的故障恢复性能。
文摘针对柔性直流输电系统常规直流电压波动抑制算法中存在的缺陷,提出一种适用于模块化多电平换流器型高压直流输电系统(modular multilevel converter based high voltage direct current,MMC-HVDC)的直流电压波动抑制方法。该方法利用MMC特有的"储能"特性,在交流系统不对称时,控制MMC交、直流侧瞬时有功功率不再平衡,从而实现MMC交流侧电流依然保持对称运行,同时直流侧电压、电流和功率保持为恒定。为了实现上述控制功能与目标,建立三相交流系统不对称时MMC直流回路的模型,设计0坐标系下以比例谐振调节器为基础的控制策略,且探讨MMC-HVDC中的协调控制问题。最后,搭建71电平背靠背MMC-HVDC系统模型进行数字仿真,结果验证了所提控制方法的有效性。
