利用柔性直流输电系统潜在的调频能力,可实现对电网频率的有效支撑。但在传统调频过程中,由于虚拟惯量的增加降低了系统对参考功率的跟踪速度,同时带来电压控制稳定裕度的降低,弱化了系统的频率支撑能力。因此,提出一种计及电压的参数...利用柔性直流输电系统潜在的调频能力,可实现对电网频率的有效支撑。但在传统调频过程中,由于虚拟惯量的增加降低了系统对参考功率的跟踪速度,同时带来电压控制稳定裕度的降低,弱化了系统的频率支撑能力。因此,提出一种计及电压的参数解耦虚拟同步发电机(virtual synchronous generator,VSG)策略。首先,对换流站辅助频率控制模型及常规VSG控制方式进行分析,引入直流母线电压,并采用带下垂的PI控制器对电压偏差进行调节。然后,对部分有功功率控制回路(active power loop,APL)进行改进,引入低通滤波器及前馈回路消除VSG固有的振荡极点,将APL的参考功率跟踪速度和VSG可提供的虚拟惯量支撑能力进行解耦。最后,利用Matlab/Simulink仿真对所提策略进行仿真验证。结果表明,所提策略能将虚拟惯量的调节和参考功率的跟踪由两参数独立控制,使控制方式更加灵活,并有效提高换流站的频率支撑能力,同时也保证了对电压的良好控制效果。展开更多
Stability of grid-connected VSCs in DC voltage control(DVC)timescales(i.e.,the frequency range of dynamics covering converter outer controls)has recently caught increased attention,while the existing approaches,such a...Stability of grid-connected VSCs in DC voltage control(DVC)timescales(i.e.,the frequency range of dynamics covering converter outer controls)has recently caught increased attention,while the existing approaches,such as eigenvalue analysis and dq-domain impedance analysis,have respective limitations on addressing these types of stability issues.This paper proposes an alternative net damping criterion dedicated for analyzing the DVC timescale stability in a multi-VSC system.This criterion is strictly mapped from the Nyquist stability criterion utilizing the gain margin concept,which preserves the advantages of the classical positive net damping criterion suggested by Canay[20]–allowing for decomposition analysis of a subsystem’s contribution to the closed-loop stability in a single-input single-output(SISO)framework,but overcomes its deficiency of possibly erroneous prediction of system dynamic behaviors.Case studies show that the proposed criterion can correctly predict some unstable conditions(e.g.,monotonic divergence)which cannot be identified by the classical net damping criterion.Additionally,the condition for when the classical criterion is available is also pointed out,the proposed criterion can also act as a complement of the classical criterion for stability examination.展开更多
针对交直流配电网波动性新能源占比高和交直流两侧协同难度大的问题,基于统一潮流计算方法,提出了一种源-网-储协调双层优化调度模型。针对交直流配电网的复杂网络结构,提出了混合整数网络矩阵描述方法,通过统一迭代实现配电网潮流计算...针对交直流配电网波动性新能源占比高和交直流两侧协同难度大的问题,基于统一潮流计算方法,提出了一种源-网-储协调双层优化调度模型。针对交直流配电网的复杂网络结构,提出了混合整数网络矩阵描述方法,通过统一迭代实现配电网潮流计算。充分考虑配电网中灵活性可调度资源与电压源型换流器(voltage source converter,VSC)的相互关系,构建了双层优化调度模型并使用知识共享获取算法(gaining sharing knowledge based algorithm,GSK)对模型进行求解,上层以经济性为指标对新能源消纳与储能进行调度,确定新能源消纳情况与储能运行状态;下层通过调节VSC控制参数与静态无功补偿装置(static var generators,SVG)输出对配电网潮流进行深层次优化,以降低网损,提高电压质量。通过改进IEEE33系统进行仿真验证。仿真结果表明:经过双层优化后,配电网运行成本明显下降,电压质量得到优化。展开更多
Vibrational strong coupling(VSC)provides a promising way towards not only enhanced control of infrared light but also reshaping of molecular properties,which opens up unprecedented opportunities in ultrasensitive infr...Vibrational strong coupling(VSC)provides a promising way towards not only enhanced control of infrared light but also reshaping of molecular properties,which opens up unprecedented opportunities in ultrasensitive infrared spectroscopy,modification of chemical reactions,and exploration of nonlinear quantum effects.Surface plasmon resonance,excited on simple plasmonic resonators in the infrared,has been demonstrated as a means to realize VSC,but suffers from either limited quality factor for realizing large Rabi splitting or poor reconfigurability for precise detuning control.Here we propose and experimentally demonstrate,for the first time,an on-chip plasmonic resonator based on degeneracy breaking of Wood’s anomaly for VSC.Leveraging the low damping rate of the surface state induced by this degeneracy breaking,we achieve a plasmonic resonance with a high-Q factor exceeding~110,resulting in a Rabi splitting up to~112 cm^(-1) with a subwavelength molecular layer.Additionally,the dispersion of the surface state allows for precise control over VSC detuning by simply adjusting the incident angle of excitation light,even in the absence of photons,enabling a broad detuning range up to 300 cm^(-1).These experimental results align well with our analytical model and numerical simulation.This work provides a promising integrated platform for VSC,with various potential applications in on-chip spectroscopy,polariton chemistry,and polariton devices.展开更多
This paper presents an improved virtual synchronous control(VSynC) for the grid-connected voltage source converter(VSC) so as to continuously operate under the grid voltage with steady unbalance.The improved VSynC int...This paper presents an improved virtual synchronous control(VSynC) for the grid-connected voltage source converter(VSC) so as to continuously operate under the grid voltage with steady unbalance.The improved VSynC introduces the negative sequence power controls on basis of conventional VSynC.The improved VSynC is capable of regulating the negative sequence internal voltage to reduce the negative-sequence injected currents and oscillated powers of the VSC aroused by the negative-sequence grid voltage.Three alternative local control objectives for the VSC itself under steady state unbalanced grid conditions and their corresponding power references are deduced and computed.Simulated and experimental results are presented to validate the correctness and effectiveness of the proposed improved VSynC to enhance the continuous operation performance of VSynC-based VSCs during grid voltage steady-state unbalance.展开更多
文摘利用柔性直流输电系统潜在的调频能力,可实现对电网频率的有效支撑。但在传统调频过程中,由于虚拟惯量的增加降低了系统对参考功率的跟踪速度,同时带来电压控制稳定裕度的降低,弱化了系统的频率支撑能力。因此,提出一种计及电压的参数解耦虚拟同步发电机(virtual synchronous generator,VSG)策略。首先,对换流站辅助频率控制模型及常规VSG控制方式进行分析,引入直流母线电压,并采用带下垂的PI控制器对电压偏差进行调节。然后,对部分有功功率控制回路(active power loop,APL)进行改进,引入低通滤波器及前馈回路消除VSG固有的振荡极点,将APL的参考功率跟踪速度和VSG可提供的虚拟惯量支撑能力进行解耦。最后,利用Matlab/Simulink仿真对所提策略进行仿真验证。结果表明,所提策略能将虚拟惯量的调节和参考功率的跟踪由两参数独立控制,使控制方式更加灵活,并有效提高换流站的频率支撑能力,同时也保证了对电压的良好控制效果。
文摘三相四桥臂换流器具备不平衡负载工作能力与三相解耦控制功能,已成为主动配电网领域的研究热点。结合三相四桥臂电压源转换器(voltage source converter,VSC)模型,提出一种分相准比例谐振控制(proportion resonant,PR)直接电流控制策略。针对台区首端电流不平衡问题,提出分相功率补偿思路。先设计补偿功率计算策略,再以功率为控制目标计算输入电流参考值,结合分相准比例谐振直接电流控制,对各相进行功率调节,以达到治理三相电流不平衡的目的。在某仿真软件搭建了基于嵌入式低压直流环节(embedded low voltage DC system,E-LVDC)的低压柔性台区模型。仿真结果表明,台区首端三相电流不平衡度降低,从而验证了所提控制策略的有效性。
基金This work was supported in part by the Research Grants Council of Hong Kong under Grant GRF 17207818the National Natural Science Foundation of China under Grant 51677160the Themebased Research Scheme(TRS)under T23-701/14-N.
文摘Stability of grid-connected VSCs in DC voltage control(DVC)timescales(i.e.,the frequency range of dynamics covering converter outer controls)has recently caught increased attention,while the existing approaches,such as eigenvalue analysis and dq-domain impedance analysis,have respective limitations on addressing these types of stability issues.This paper proposes an alternative net damping criterion dedicated for analyzing the DVC timescale stability in a multi-VSC system.This criterion is strictly mapped from the Nyquist stability criterion utilizing the gain margin concept,which preserves the advantages of the classical positive net damping criterion suggested by Canay[20]–allowing for decomposition analysis of a subsystem’s contribution to the closed-loop stability in a single-input single-output(SISO)framework,but overcomes its deficiency of possibly erroneous prediction of system dynamic behaviors.Case studies show that the proposed criterion can correctly predict some unstable conditions(e.g.,monotonic divergence)which cannot be identified by the classical net damping criterion.Additionally,the condition for when the classical criterion is available is also pointed out,the proposed criterion can also act as a complement of the classical criterion for stability examination.
文摘针对交直流配电网波动性新能源占比高和交直流两侧协同难度大的问题,基于统一潮流计算方法,提出了一种源-网-储协调双层优化调度模型。针对交直流配电网的复杂网络结构,提出了混合整数网络矩阵描述方法,通过统一迭代实现配电网潮流计算。充分考虑配电网中灵活性可调度资源与电压源型换流器(voltage source converter,VSC)的相互关系,构建了双层优化调度模型并使用知识共享获取算法(gaining sharing knowledge based algorithm,GSK)对模型进行求解,上层以经济性为指标对新能源消纳与储能进行调度,确定新能源消纳情况与储能运行状态;下层通过调节VSC控制参数与静态无功补偿装置(static var generators,SVG)输出对配电网潮流进行深层次优化,以降低网损,提高电压质量。通过改进IEEE33系统进行仿真验证。仿真结果表明:经过双层优化后,配电网运行成本明显下降,电压质量得到优化。
基金supported by the National Key Research and Development Program of China(Grant No.2024YFE0105200)the National Nature Science Foundation of China(Grant No.62405284)+2 种基金the Key Research and Development Program of Henan Province(Grant No.241111220600)the JSPS KAKENHI(Grant No.JP20K14785)the Murata Science Foundation.
文摘Vibrational strong coupling(VSC)provides a promising way towards not only enhanced control of infrared light but also reshaping of molecular properties,which opens up unprecedented opportunities in ultrasensitive infrared spectroscopy,modification of chemical reactions,and exploration of nonlinear quantum effects.Surface plasmon resonance,excited on simple plasmonic resonators in the infrared,has been demonstrated as a means to realize VSC,but suffers from either limited quality factor for realizing large Rabi splitting or poor reconfigurability for precise detuning control.Here we propose and experimentally demonstrate,for the first time,an on-chip plasmonic resonator based on degeneracy breaking of Wood’s anomaly for VSC.Leveraging the low damping rate of the surface state induced by this degeneracy breaking,we achieve a plasmonic resonance with a high-Q factor exceeding~110,resulting in a Rabi splitting up to~112 cm^(-1) with a subwavelength molecular layer.Additionally,the dispersion of the surface state allows for precise control over VSC detuning by simply adjusting the incident angle of excitation light,even in the absence of photons,enabling a broad detuning range up to 300 cm^(-1).These experimental results align well with our analytical model and numerical simulation.This work provides a promising integrated platform for VSC,with various potential applications in on-chip spectroscopy,polariton chemistry,and polariton devices.
基金supported by National Natural Science Foundation of China (No.51607130)National Key Research and Development Program (No.2016YFB0900104)National Natural Science Fund for Excellent Young Scholars (No.51322704)
文摘This paper presents an improved virtual synchronous control(VSynC) for the grid-connected voltage source converter(VSC) so as to continuously operate under the grid voltage with steady unbalance.The improved VSynC introduces the negative sequence power controls on basis of conventional VSynC.The improved VSynC is capable of regulating the negative sequence internal voltage to reduce the negative-sequence injected currents and oscillated powers of the VSC aroused by the negative-sequence grid voltage.Three alternative local control objectives for the VSC itself under steady state unbalanced grid conditions and their corresponding power references are deduced and computed.Simulated and experimental results are presented to validate the correctness and effectiveness of the proposed improved VSynC to enhance the continuous operation performance of VSynC-based VSCs during grid voltage steady-state unbalance.
