通过对含静止无功补偿器(static var compensator,SVC)的单机无穷大(single machine infinite-bus,SIMB)系统进行电磁转矩计算,从理论上分析SVC的电压控制和阻尼调节之间的相互作用关系,既要保证同时为系统提供正的同步转矩和阻尼转矩,...通过对含静止无功补偿器(static var compensator,SVC)的单机无穷大(single machine infinite-bus,SIMB)系统进行电磁转矩计算,从理论上分析SVC的电压控制和阻尼调节之间的相互作用关系,既要保证同时为系统提供正的同步转矩和阻尼转矩,电压控制增益和阻尼控制增益的取值需满足一定的限制关系。通过对PSASP中36节点系统进行特征值分析,从广义阻尼的角度分析SVC控制参数对系统阻尼的影响。分析结果表明,电压控制增益和时间常数可改变系统的总阻尼,阻尼控制增益只能对系统的阻尼特性进行重新配置,从而改善系统的弱阻尼区间振荡模式。仿真验证了上述结论的有效性。展开更多
The deployment of a synchrophasor-based widearea measurement system(WAMS) in a power grid largely improves the observability of power system dynamics and the operator’s real-time situational awareness for potential s...The deployment of a synchrophasor-based widearea measurement system(WAMS) in a power grid largely improves the observability of power system dynamics and the operator’s real-time situational awareness for potential stability issues. The WAMS in many power grids has successfully captured system oscillation events, e.g. poorly damped natural oscillations and forced oscillations, from time to time. To identify the root cause of an observed oscillation event for further mitigation actions, many methods have been proposed to locate the source of oscillation based on different ideas and principles. However, most methods proposed so far for locating the oscillation source in a power grid are not reliable enough for practical applications. This paper presents a comprehensive review of existing location methods, which basically fall into four major categories, plus a few other methods. Their advantages and disadvantages are discussed in detail. Some trends and challenges on the problem of oscillation source location are pointed out along with potential future research directions. Finally, a practical, general scheme for oscillation source location using available location methods is suggested and analyzed.展开更多
针对规模化光伏电站并网出现系统稳定性下降问题,提出光伏并网逆变器改进功率外环控制策略提高系统抗干扰能力。首先,推导分析了光伏电站改进控制策略增加系统正阻尼转矩机理,通过多目标遗传算法优化并设计了H∞回路成形权函数,采用总...针对规模化光伏电站并网出现系统稳定性下降问题,提出光伏并网逆变器改进功率外环控制策略提高系统抗干扰能力。首先,推导分析了光伏电站改进控制策略增加系统正阻尼转矩机理,通过多目标遗传算法优化并设计了H∞回路成形权函数,采用总体最小二乘/旋转矢量不变技术(total least squares/estimating signal parameter via rotational invariance techniques,TLS-ESPRIT)辨识得到系统振荡模态及开环模型。然后,设计了逆变器附加H∞阻尼控制并对控制参数进行整定。最后,以某实际运行光伏电站为例,依托RT-LAB平台搭建光伏并网系统主电路模型并进行控制器硬件在环测试(hardware in the loop,HIL)。仿真结果表明,基于回路成形的附加控制策略提升了光伏并网系统稳定性。展开更多
The mode-based damping torque analysis(M-DTA)method for studying the effect of an external controller on power system low-frequency oscillations is proposed in this paper.First,based on the interconnection model betwe...The mode-based damping torque analysis(M-DTA)method for studying the effect of an external controller on power system low-frequency oscillations is proposed in this paper.First,based on the interconnection model between the system and the controller in the frequency domain,the oscillation loop corresponding to the electromechanical oscillation mode is built,and then the mode-based damping torque of the controller can be calculated.Then,the application of the M-DTA method in the power system is illustrated.The derivation shows that in the single-machine infinite-bus power system,the M-DTA method is completely equivalent to the classical damping torque analysis(C-DTA)method.In the multi-machine power system,the mode-based damping torque directily reflects the effect of the controller on the oscillation mode,overcoming the shortcomings of the C-DTA method in which there is no direct correspondence between the damping torque and the oscillation mode.By deriving the relationship with the residue index,the M-DTA method shows higher accuracy than the residue method in applications,such as controller parameter adjustment.Finally,two example power systems are presented to demonstrate the application of the proposed M-DTA method.Index Terms-Electromechanical oscillation mode,FACTS,interconnection model in the frequency domain,mode-based damping torque analysis(M-DTA),power system low-frequency oscillation,PSS,residue method.展开更多
Antiferromagnets have been attracting tremendous interest in the spintronics community due to their intrinsic appealing properties,such as zero stray field and ultrafast spin dynamics.Recently,the electrical manipulat...Antiferromagnets have been attracting tremendous interest in the spintronics community due to their intrinsic appealing properties,such as zero stray field and ultrafast spin dynamics.Recently,the electrical manipulation of bulk properties of antiferromagnets has been widely studied,but exploring the use of antiferromagnetic(AFM)interfacial properties to investigate some key issues in spintronic devices is urgently desired.In this study,the magnetic and spin transport properties mediated by interlayer exchange coupling(IEC)are examined through spin-orbit torque(SOT)-induced tunability of interfacial spins in heavy-metal/like-synthetic antiferromagnet/antiferromagnet heterostructure devices.We found that the exchange bias and coercivity and the critical current density for SOT switching can be modulated by IEC,associating with the oscillation of SOTinduced interfacial spins reorientation at zero field,which can be well understood with the modified Ruderman-Kittel-KasuyaYosida model.Our finding opens a new route for understanding and using the AFM interfacial spins in spintronics.展开更多
文摘通过对含静止无功补偿器(static var compensator,SVC)的单机无穷大(single machine infinite-bus,SIMB)系统进行电磁转矩计算,从理论上分析SVC的电压控制和阻尼调节之间的相互作用关系,既要保证同时为系统提供正的同步转矩和阻尼转矩,电压控制增益和阻尼控制增益的取值需满足一定的限制关系。通过对PSASP中36节点系统进行特征值分析,从广义阻尼的角度分析SVC控制参数对系统阻尼的影响。分析结果表明,电压控制增益和时间常数可改变系统的总阻尼,阻尼控制增益只能对系统的阻尼特性进行重新配置,从而改善系统的弱阻尼区间振荡模式。仿真验证了上述结论的有效性。
基金supported by the NSF CURENT Engineering Research Center(No.EEC-1041877)
文摘The deployment of a synchrophasor-based widearea measurement system(WAMS) in a power grid largely improves the observability of power system dynamics and the operator’s real-time situational awareness for potential stability issues. The WAMS in many power grids has successfully captured system oscillation events, e.g. poorly damped natural oscillations and forced oscillations, from time to time. To identify the root cause of an observed oscillation event for further mitigation actions, many methods have been proposed to locate the source of oscillation based on different ideas and principles. However, most methods proposed so far for locating the oscillation source in a power grid are not reliable enough for practical applications. This paper presents a comprehensive review of existing location methods, which basically fall into four major categories, plus a few other methods. Their advantages and disadvantages are discussed in detail. Some trends and challenges on the problem of oscillation source location are pointed out along with potential future research directions. Finally, a practical, general scheme for oscillation source location using available location methods is suggested and analyzed.
文摘针对规模化光伏电站并网出现系统稳定性下降问题,提出光伏并网逆变器改进功率外环控制策略提高系统抗干扰能力。首先,推导分析了光伏电站改进控制策略增加系统正阻尼转矩机理,通过多目标遗传算法优化并设计了H∞回路成形权函数,采用总体最小二乘/旋转矢量不变技术(total least squares/estimating signal parameter via rotational invariance techniques,TLS-ESPRIT)辨识得到系统振荡模态及开环模型。然后,设计了逆变器附加H∞阻尼控制并对控制参数进行整定。最后,以某实际运行光伏电站为例,依托RT-LAB平台搭建光伏并网系统主电路模型并进行控制器硬件在环测试(hardware in the loop,HIL)。仿真结果表明,基于回路成形的附加控制策略提升了光伏并网系统稳定性。
基金supported in part by the National Natural Science Foundation of China under Grant No.U1766202,51907179 and 51977197.
文摘The mode-based damping torque analysis(M-DTA)method for studying the effect of an external controller on power system low-frequency oscillations is proposed in this paper.First,based on the interconnection model between the system and the controller in the frequency domain,the oscillation loop corresponding to the electromechanical oscillation mode is built,and then the mode-based damping torque of the controller can be calculated.Then,the application of the M-DTA method in the power system is illustrated.The derivation shows that in the single-machine infinite-bus power system,the M-DTA method is completely equivalent to the classical damping torque analysis(C-DTA)method.In the multi-machine power system,the mode-based damping torque directily reflects the effect of the controller on the oscillation mode,overcoming the shortcomings of the C-DTA method in which there is no direct correspondence between the damping torque and the oscillation mode.By deriving the relationship with the residue index,the M-DTA method shows higher accuracy than the residue method in applications,such as controller parameter adjustment.Finally,two example power systems are presented to demonstrate the application of the proposed M-DTA method.Index Terms-Electromechanical oscillation mode,FACTS,interconnection model in the frequency domain,mode-based damping torque analysis(M-DTA),power system low-frequency oscillation,PSS,residue method.
基金supported by the National Key R&D Program of China(Grant No.2017YFB0405700)the National Natural Science Foundation of China(Grant Nos.11474272,and 61774144)+1 种基金the Beijing Natural Science Foundation Key Program(Grant No.Z190007)the Chinese Academy of Sciences(Grant Nos.QYZDY-SSW-JSC020,XDB28000000,and XDPB44000000)。
文摘Antiferromagnets have been attracting tremendous interest in the spintronics community due to their intrinsic appealing properties,such as zero stray field and ultrafast spin dynamics.Recently,the electrical manipulation of bulk properties of antiferromagnets has been widely studied,but exploring the use of antiferromagnetic(AFM)interfacial properties to investigate some key issues in spintronic devices is urgently desired.In this study,the magnetic and spin transport properties mediated by interlayer exchange coupling(IEC)are examined through spin-orbit torque(SOT)-induced tunability of interfacial spins in heavy-metal/like-synthetic antiferromagnet/antiferromagnet heterostructure devices.We found that the exchange bias and coercivity and the critical current density for SOT switching can be modulated by IEC,associating with the oscillation of SOTinduced interfacial spins reorientation at zero field,which can be well understood with the modified Ruderman-Kittel-KasuyaYosida model.Our finding opens a new route for understanding and using the AFM interfacial spins in spintronics.
