Droop-based fast frequency response(FFR)control of wind turbines can improve the frequency performance of power systems with high penetration of wind power.Explicitly formulating the feasible region of the droop-based FFR controller parameters can allow system operators to conveniently assess the feasibility of FFR controller parameter settings to comply with system frequency security,and efficiently tune and optimize FFR controller parameters to meet frequency security requirements.However,the feasible region of FFR controller parameters is inherently nonlinear and implicit because the power point tracking controllers of wind turbine would counteract the effect of FFR controllers.To address this issue,this letter proposes a linear feasible region formulation method,where frequency regulation characteristics of wind turbines,the dead band,and reserve limits of generators are all considered.The effectiveness of the proposed method and its application is demonstrated on a 10-machine power system.
In this paper,a cost-effective and miniaturized instrument is proposed,which is based on a tunable modulated grating Y-branch(MG-Y)laser for rapid temperature measurement using a Fabry-Perot interferometer(FPI)sensor.The FPI sensor with a 1463-μm cavity length is a short segment of a capillary tube sandwiched by two sections of single-mode fibers(SMFs).This system has a broad tunable range(1527 nm-1567 nm)with a wavelength interval of 8 pm and a tuning rate of 100 Hz.Temperature sensing experiments are carried out to investigate the performance of the system by demodulating the absolute cavity length of the FPI sensor using a cross-correlation algorithm.Experimental results show that the sensor can reach the response time as short as 94 ms with the sensitivity of 802 pm/C.Benefiting from the homemade and integrated essential electrical circuits,the entire system has the small size,low cost,and practical application potential to be used in the harsh environment for rapid temperature measurement.
Yang CHEUNGZhenguo JINGQiang LIUAng LIYueying LIUYihang GUOSen ZHANGDapeng ZHOUWei PENG
In recent years,multi-modal flexible tactile sensors have become an important direction in the development of electronic skin because of their excellent sensitivity,flexibility and wearable properties.In this work,a humidity-pressure multi-modal flexible sensor based on polypyrrole(PPy)/Ti_(3)C_(2)T_(x) sensitive film packaged with porous polydimethylsiloxane(PDMS)is investigated by combining the sensitive structure generation mechanism of in situ polymerization to achieve the simultaneous detection of humidity and pressure,which has a sensitivity of 89,113.4Ω/%RH in a large humidity range of 0%-97%RH,and response/recovery time of 2.5/1.9 s.The tactile pressure sensing has a high sensitivity,a fastresponse of 67/52 ms,and a wide detection limit.The device also has excellent performance in terms of stability and repeatability,making it promising for respiratory pattern and motion detection.This work provides a new solution to address the construction of multi-modal tactile sensors with potential applications in the fields of medical health,epidemic prevention.
Two-dimensional(2D)non-layered materials,along with their unique surface properties,offer intriguing prospects for sensing applications.Introducing mechanical degrees of freedom is expected to enrich the sensing performances of 2D non-layered devices,such as high frequency,high tunability,and large dynamic range,which could lead to new types of high performance nanosensors.Here,we demonstrate 2D non-layered nanomechanical resonant sensors based onβ-In_(2)S_(3),where the devices exhibit robust nanomechanical vibrations up to the very high frequency(VHF)band.We show that such device can operate as pressure sensor with broad range(from 103 Torr to atmospheric pressure),high linearity(with a nonlinearity factor as low as 0.0071),and fastresponse(with an intrinsic response time less than 1μs).We further unveil the frequency scaling law in theseβ-In_(2)S_(3) nanomechanical sensors and successfully extract both the Young's modulus and pretension for the crystal.Our work paves the way towards future wafer-scale design and integrated sensors based on 2D non-layered materials.
