The performance of DFIG-based wind generation systems that interconnected to solid networks is well understood and prevalent in Europe and North America. However, the application of these renewable generating stations...The performance of DFIG-based wind generation systems that interconnected to solid networks is well understood and prevalent in Europe and North America. However, the application of these renewable generating stations to weak network has been examined in very limited occasions. Weak networks have a range of limitations from system capacities to CFCT restrictions which would need to be well understood prior to wind energy integration. Of particular interest would be how much wind generation could be integrated into a weak network prior to increasing voltage and frequency stability issues brought about by penetration issues. This paper introduces a simple and practical approach based on the equal area criteria to investigate the stability of weak networks. Simulation results that are presented to show the proposed approach is a viable preliminary assessment tool to determine system stability on weak networks with wind power penetration.展开更多
In this study,we investigate the tunneling of fermions with arbitrary spin near the event horizon of a nonstationary Vaidya-Bonner-de Sitter(VBdS)black hole under Lorentz invariance violation(LIV).The modified Hawking...In this study,we investigate the tunneling of fermions with arbitrary spin near the event horizon of a nonstationary Vaidya-Bonner-de Sitter(VBdS)black hole under Lorentz invariance violation(LIV).The modified Hawking temperature of VBdS black holes is calculated by using tortoise coordinate transformation,Feynman prescription,and Wentzel-Kramers-Brillouin approximation.By considering the cosmological constant as a thermodynamic pressure in the extended phase space,we construct a Maxwell's equal area law under LIV and study the phase transitions of VBdS black hole in P-v,P-V,and T-S planes.The LIV increases the length of the liquid-gas coexistence region.The thermodynamic quantities such as the entropy,heat capacity,Helmholtz free energy,internal energy,enthalpy,and Gibbs free energy of the VBdS black hole are discussed.These quantities tend to increase under LIV.The stability of the black hole is also discussed in the presence of LIV.展开更多
多直流送端系统内某一直流线路发生闭锁故障后,可以通过对其他非故障直流进行紧急功率支援(emergency DC power support,EDCPS)控制来提升系统受扰后的稳定性。如何有效量化EDCPS对系统稳定性的改善效果,从而提高安稳控制的效率,目前缺...多直流送端系统内某一直流线路发生闭锁故障后,可以通过对其他非故障直流进行紧急功率支援(emergency DC power support,EDCPS)控制来提升系统受扰后的稳定性。如何有效量化EDCPS对系统稳定性的改善效果,从而提高安稳控制的效率,目前缺少相应的指标;现有研究也尚未解决如何利用EDCPS最大程度提升多直流综合送出能力的问题。应用扩展等面积法(extended equal area criterion,EEAC)定量分析了EDCPS提升多直流送端系统暂态稳定性的机理;以两送出直流系统为例,推导了基于EEAC的暂态稳定裕度η对EDCPS的灵敏度公式;在此基础上,提出一种在不增加相关设备投入的前提下利用系统中现有稳控措施并结合暂态稳定裕度灵敏度的多直流送出能力提升控制方法,通过计算备选直流的暂态稳定裕度灵敏度,可以完整反映系统在遭受大扰动后的动态特性以及定量评估EDCPS对系统受扰后稳定性的改善效果,避免过去仅凭运行人员经验选取支援直流的问题,提高计算效率;最后,选取西北电网实际算例对所提出的多直流送出能力提升控制方法有效性进行仿真验证,以期为从事交直流混联电力系统稳定性分析与控制的学者和工程师们提供有益的参考。展开更多
文摘The performance of DFIG-based wind generation systems that interconnected to solid networks is well understood and prevalent in Europe and North America. However, the application of these renewable generating stations to weak network has been examined in very limited occasions. Weak networks have a range of limitations from system capacities to CFCT restrictions which would need to be well understood prior to wind energy integration. Of particular interest would be how much wind generation could be integrated into a weak network prior to increasing voltage and frequency stability issues brought about by penetration issues. This paper introduces a simple and practical approach based on the equal area criteria to investigate the stability of weak networks. Simulation results that are presented to show the proposed approach is a viable preliminary assessment tool to determine system stability on weak networks with wind power penetration.
文摘In this study,we investigate the tunneling of fermions with arbitrary spin near the event horizon of a nonstationary Vaidya-Bonner-de Sitter(VBdS)black hole under Lorentz invariance violation(LIV).The modified Hawking temperature of VBdS black holes is calculated by using tortoise coordinate transformation,Feynman prescription,and Wentzel-Kramers-Brillouin approximation.By considering the cosmological constant as a thermodynamic pressure in the extended phase space,we construct a Maxwell's equal area law under LIV and study the phase transitions of VBdS black hole in P-v,P-V,and T-S planes.The LIV increases the length of the liquid-gas coexistence region.The thermodynamic quantities such as the entropy,heat capacity,Helmholtz free energy,internal energy,enthalpy,and Gibbs free energy of the VBdS black hole are discussed.These quantities tend to increase under LIV.The stability of the black hole is also discussed in the presence of LIV.
文摘多直流送端系统内某一直流线路发生闭锁故障后,可以通过对其他非故障直流进行紧急功率支援(emergency DC power support,EDCPS)控制来提升系统受扰后的稳定性。如何有效量化EDCPS对系统稳定性的改善效果,从而提高安稳控制的效率,目前缺少相应的指标;现有研究也尚未解决如何利用EDCPS最大程度提升多直流综合送出能力的问题。应用扩展等面积法(extended equal area criterion,EEAC)定量分析了EDCPS提升多直流送端系统暂态稳定性的机理;以两送出直流系统为例,推导了基于EEAC的暂态稳定裕度η对EDCPS的灵敏度公式;在此基础上,提出一种在不增加相关设备投入的前提下利用系统中现有稳控措施并结合暂态稳定裕度灵敏度的多直流送出能力提升控制方法,通过计算备选直流的暂态稳定裕度灵敏度,可以完整反映系统在遭受大扰动后的动态特性以及定量评估EDCPS对系统受扰后稳定性的改善效果,避免过去仅凭运行人员经验选取支援直流的问题,提高计算效率;最后,选取西北电网实际算例对所提出的多直流送出能力提升控制方法有效性进行仿真验证,以期为从事交直流混联电力系统稳定性分析与控制的学者和工程师们提供有益的参考。
