Research on the Impacts of the Inertia and Droop Control Gains from a Variable-Speed Wind Turbine Generator on the Frequency Response

System frequency must be kept very close to its nominal range to ensure the stability of an electric power grid.Excessive system frequency variations are able to result in load shedding,frequency instability,and even generator damage.With increasing wind power penetration,there is rising concern about the reduction in inertia response and primary frequency control in the electric power grid.Converter-based wind generation is capable of providing inertia response and primary frequency response;nevertheless,the primary frequency and inertia responses of wind generation are different from those of conventional synchronous fleets;it is not completely understood how the primary frequency and inertia responses affect the given system under various disturbances and available kinetic energy levels.Simulations are used to investigate the influences of inertia and droop control strategies on the dynamic frequency responses,particularly the index of the second frequency drop under various disturbance and wind conditions.A quantitative analysis provides insight into setting of inertia and droop control coefficients for various wind and disturbance conditions to facilitate adequate dynamic frequency responses during frequency events.

Protein farnesylation negatively regulatesbrassinosteroid signaling via reducing BES1 stabilityinArabidopsis thaliana^(∞)

Brassinosteroids(BRs)are a group of steroidal phytohormones,playing critical roles in almost all physiological aspects during the life span of a plant.In Arabidopsis,BRs are perceived at the cell surface,triggering a reversible phosphorylation-based signaling cascade that leads to the activation and nuclear accumulation of a family of transcription factors,represented by BES1 and BZR1.Protein famesylation is a type of post-translational modification,functioning in many important cellular processes.Previous studies demonstrated a role of famesylation in BR biosynthesis via regulating the endoplasmic reticulum localization of a key bassino-lide(BL)biosynthetic enzyme BR6ox2.Whether such a process is also involved in BR signaling is not understood.Here,we demonstrate that protein famesylation is involved in mediating BR signaling in Arabidopsis.A loss-of-function mutant of EN HANCED RESPONSE TO ABA 1(iERA1).encoding a(3 subunit of the protein famesyl transferase hoi oenzyme,can alter the BL sensitivity of bak1~4 from a reduced to a hypersensitive level,era 7 can partially rescue the BR defective phenotype of a hetero zygous mutant of bin2-1,a gain-of function mutant of BIN2 which encodes a negative regulator in the BR signaling.Our genetic and biochemical analyses revealed that ERA1 plays a significant role in regulating the protein stability of BES1.