Dual Loop Research Articles

Intelligent finite-time formation control for flapping wing micro aerial vehicles

This paper investigates the intelligent finite time formation control for multiple Flapping wing micro aerial vehicles (FWMAVs) system. Firstly, the translational and the rotational attitude motion equations are proposed based on the Lagrangian equation for FWMAVs. The motion system is decouple into an internal and an external dual loop subsystems. An adaptive neural network estimation algorithm is proposed based on the internal and external double loop system of the coupled model to effectively estimate the uncertainties and the external disturbances of the model. In addition, two effective intelligent control protocols are presented for the translational and the rotational attitude motion subsystem, respectively, by utilizing potential energy function, generalized inverse matrix, and finite-time stability. The main contribution of this paper is the case that, four control objectives are achieved for multiple FWMAVs system, including the estimation of uncertainties, collision avoidance, connectivity preservation, and finite time convergence. Finally, a simulation example of formation tracking control is given by using matlab software in the numerical simulation part, and the effectiveness of the obtained results and the superiority of the control protocol are verified.

A Two-Degree-of-Freedom PID Integral Super-Twisting Controller Based on Atom Search Optimizer Applied to DC-DC Interleaved Converters for Fuel Cell Applications

This paper focuses on the real-time implementation of an optimal high-performance control applied to an interleaved nonisolated DC/DC converter designed for fuel cell applications. Three-phase interleaved boost converters are utilized to minimize input current undulation, increase efficiency, and provide a high output voltage in order to ensure the performance of the FC stack. The proposed control strategy contains an outer loop that generates the reference current based on a two-degree-of-freedom PID controller. This controller provides a robust setpoint tracking and disturbance rejection, which improves the system’s response and efficiency. A fast inner regulation loop based on a super-twisting integral sliding mode (STISM) algorithm is developed to achieve a fixed converter output voltage, equitable phase current sharing, and fast regulation against load disturbances in failure operation. The STISM algorithm exhibits a rapid convergence property of the sliding mode and effectively avoids the chattering phenomena frequently observed in conventional sliding modes. The proposed controller’s gains are determined using the atom search optimization algorithm, which ensures exceptional reliability and a high degree of robustness and stability of the controllers under a variety of operational conditions. This method is inspired from the behavior of atoms and their electrons during the excitation process leading to a one-of-a-kind optimization technique which contributes to the controller’s reliability. Using Matlab-Simulink simulation tools, the efficacy and performance of the designed control have first been evaluated and assessed and compared with other optimization algorithms, and then with a dual loop based on a PID controller. Then, they have been verified by real-time hardware implementation on a 1.2 KW prototype FC converter driven by the dSPACE-1104 card under a variety of tests. The suggested approach offers impressive experimental results in dynamic and steady states.

Multi-objective grey wolf optimization of four different geothermal flash -organic Rankine power cycles

Geothermal energy, a sustainable and abundant resource, has garnered significant attention for its potential to contribute to the world's growing energy demands. Integrating organic Rankine cycles with geothermal flash cycles has emerged as a promising avenue in this pursuit. Four feasible arrangements are proposed, and their productivity and thermodynamic/economic criteria are compared. The four processes include a single flash-single loop, a dual flash-single loop, a single flash-dual loop, and a dual flash-dual loop. These structures are optimized in four scenarios: energetic efficiency/net output electrical power, energetic efficiency/payback period, exergetic efficiency/net output electrical power, and exergetic efficiency/payback period. The optimization results show that a dual flash–dual loop brings out the optimum productivity compared to the other arranged structures. The dual flash–dual loop configuration consistently outperforms the others, emerging as the optimal solution for maximizing productivity while ensuring economic viability in geothermal energy utilization via organic Rankine cycles. In conclusion, this study not only advances understanding of the synergistic potential between organic Rankine cycles and geothermal flash cycles but also provides invaluable guidance for stakeholders seeking to harness the full potential of geothermal energy with a keen eye on efficiency, sustainability, and economic feasibility.

Voltage unbalance and inertia based frequency control framework considering intelligent load management for stand-alone operation of microgrid

The less inertial microgrid with high penetration of Renewable Energy Sources (RES) faces several issues including voltage and frequency unbalance. The intermittent nature of RES-based Distributed Generations (DGs) makes the system unstable in the absence of a control mechanism in a stand-alone microgrid. The integration of single-phase loads and sudden load switching on the distribution side make the system prone to several malicious events. The unbalance in voltage among the phases and the high Rate of Change of Frequency (RoCoF) are the major concern for degrading the system’s performance during peak and off-peak hours. The paper addresses a hierarchical dual loop voltage and frequency control mechanism where the primary control is equipped with droop strategy and Positive-Negative Sequence Control (PNSC) to maintain Voltage Unbalance Factor (VUF) and adhere to IEC-61000-3-13. Further, the inertial loop is also implemented to mitigate frequency deviation and reduce transient overshoot. The secondary control mechanism enables intelligent load management by scheduling Thermostatic Control Loads (TCLs) during peak hours. The utmost care is taken for the Customer’s Thermal Comfort (CTC) while scheduling the loads. The rigorous simulation is done in MATLAB Simulink and Digsilent Power Factory with a modified IEEE 13 bus system considering system dynamics. Further, the real-time simulation is also performed with OPAL-RT to validate the efficacy of the above methodology.

Performance analysis of a separator assisted dual-evaporators two-phase thermosyphon loop under heating power maldistribution condition based on an experimentally validated model

Multiple evaporators two-phase thermosyphon loop is typical pattern which is utilized in the data centers. Under heating power maldistribution condition, the system could suffer in the temperature oscillation and performance degradation which limit its application. To solve this problem, a separator assisted dual-evaporators thermosyphon loop (SDTPTL) is evaluated and compared with traditional dual-evaporators thermosyphon loop (DTPTL) by using experimentally validated model. The simulation results show that the SDTPTL can always achieve better performances than the DTPTL at any operating conditions. Evaporator outer wall temperatures of two evaporators in the SDTPTL are lower than that in the DTPTL about 2.2––5.9 °C and 3.8–8.2 °C when heat load of evaporator2 (high heating power) ranges from 0.8 kW to 1.4 kW, and lower about 1.6–4 °C and 1.7–4 °C when heat load of evaporator1 (low heating power) ranges from 0.1 kW to 0.5 kW, respectively. Besides, compared with the DTPTL, the SDTPTL has a better benefit in evaporator outer wall temperatures at higher heat load and working fluid charge. In addition, to further improve the performances of the SDTPTL, the sensitivity analyses about structure configurations of the system are conducted as well. Results show that the system can achieve better performances at lower separator height. The evaporator outer wall temperatures of two evaporators can be decreased about 57.4 °C and 3.6 °C when separator height reduces from 0.8 m to 0.2 m. It is expected that this new cycle will be beneficial to develop dual evaporators thermosyphon loop under heating power maldistribution condition.

A novel dual power-driven electric power steering system for electric commercial vehicles

To solve the power limitation problem faced by the development of EPS system for commercial vehicles and achieve the high-performance steering, this article presents a novel dual power-driven electric power steering system (DPEPS) for commercial vehicles by using the open winding permanent magnet synchronous motor (OPMSM) fed by dual inverter with high and low DC voltage supplies. First, the two-level control strategy is introduced for the developed DPEPS system, where the upper control is designed to make the actual steering follow the expected steering performance as determined by the assistant torque curve and to generate the appropriate target current according to the vehicle speed and steering torque. And then the lower control consists of the synthetical space vector control scheme and dual PI control loop is used to execute commands from the upper control, which can make the motor execute the appropriate power supply method according to the steering torque and assist current. Finally, a co-simulation model is carried out for an electric bus, and based on which the proposed DPEPS system is validated.

Voltage Detection-Based Selective Harmonic Current Compensation Strategies for Photovoltaic Inverters

Voltage and current detection-based harmonic current compensation (VDB-HCC and CDB-HCC, respectively) strategies allow the use of photovoltaic (PV) inverters to enhance the grid power quality. CDB-HCC strategies require converter hardware retrofit by inserting an extra current sensor to measure load or downstream grid currents. On the other hand, VDB-HCC strategies are straightforward solutions employing only embedded measurements used for protection, control, and synchronization purposes. This paper provides a comprehensive comparison of three VDB-HCC strategies: VDB-HCC based on a single current loop (SCL); VDB-HCC based on dual parallel current control loops (DCL); and VDB-HCC based on parallel voltage and current control loops (VCL). The comparison includes the requirement of harmonic detection algorithms, PV array maximum power point tracking (MPPT) performance, stability over grid impedance variations and inverter power rating, steady-state harmonic compensation, enabling transient response, and computational burden. Experimental results using a 1.5-kW commercial PV inverter are conducted. Based on distributed HCC applications by PV systems, VCL has shown the best performance in terms of voltage distortion reduction under weak grids.

Modelling and control of grid connected microgrid with hybrid energy storage system

<p class="JESAbstract"><span lang="EN-US">This paper presents a photovoltaic (PV) microgrid with battery and super capacitor hybrid energy storage systems. The proposed microgrid system is designed for both grid connected and standalone mode with coordinated control-based energy management system, which controls DC link voltage, voltage and frequency balance at point of common coupling. DC link voltage control is implemented using dual loop PI controller-based voltage controller and inverter control is based on D-Q reference frame technique. The microgrid system is demonstrated in MATLAB/Simulink. The</span><span lang="EN-US"> presentati</span><span lang="EN-US">on</span><span lang="EN-US"> of the planned energy supervision system is analyzed for varying generation and load condition. In the proposed microgrid the battery energy storage system is utilized to provide long term energy during average power requirement and supercapacitor energy storage system is utilized to provide short term power requirements during sudden load variation, generation variation and during transition of modes. Designed energy management system performs effectively in grid connected mode, standalone mode with smooth transition between the modes. And it maintains dc bus voltage of the microgrid constant irrespective of load and generation variations and also during mode changing conditions.</span></p>

Inter-Comparison of Radon Measurements from a Commercial Beta-Attenuation Monitor and ANSTO Dual Flow Loop Monitor

Radon (Rn) is a radioactive, colourless, odourless, noble gas that decays rapidly. It’s most stable isotope, 222Rn, has a half-life of around 3.8 days. Atmospheric radon measurements play an important role in understanding our atmospheric environments. Naturally occurring radon can be used as an atmospheric tracer for airmass tracking, to assist in modelling boundary layer development, and is important for understanding background radiation levels and personal exposure to natural radiation. The daughter products from radon decay also play an important role when measuring fine particle pollution using beta-attenuation monitors (BAM). Beta radiation from the 222Rn decay chain interferes with BAM measurements of fine particles; thus, some BAMs incorporate radon measurements into their sampling systems. BAMs are ubiquitous in air quality monitoring networks globally and present a hitherto unexplored source of dense, continuous radon measurements. In this paper, we compare in situ real world 222Rn measurements from a high quality ANSTO dual flow loop, dual filter radon detector, and the radon measurements made by a commercial BAM instrument (Thermo 5014i). We find strong correlations between systems for hourly measurements (R2 = 0.91), daily means (R2 = 0.95), hour of day (R2 = 0.72–0.94), and by month (R2 = 0.83–0.94). The BAM underestimates radon by 22–39%; however, the linear response of the BAM measurements implies that they could be corrected to reflect the ANSTO standard measurements. Regardless, the radon measurements from BAMs could be used with correction to estimate local mixed layer development. Though only a 12-month study at a single location, our results suggest that radon measurements from BAMs can complement more robust measurements from standard monitors, augment radon measurements across broad regions of the world, and provide useful information for studies using radon as a tracer, particularly for boundary layer development and airmass identification.

Optimization of data packet encryption algorithm in network link transport layer

ABSTRACT With the rapid development of information technology, huge data information is exchanged every moment in various types of networks, which contain information such as commercial secrets and personal privacy, and data security has a great impact on people’s lives. To address the issues of low efficiency and poor security in network link transmission layer database security encryption systems, a new system is studied and designed to strengthen the protection of data information from both hardware and software aspects. Then, a discrete chaotic system is introduced to ensure the stability of the dynamic grouping encryption algorithm. Finally, trajectory loop rotation is used to obtain address clusters using the discrete chaotic system, and dual address loop rotation is used to achieve the variability of the dynamic grouping algorithm. The experiment shows that for different file sizes, the encryption speed of the Dynamic Packet Encryption Optimization (DPEO) algorithm is stable between 5.84 and 5.98 mb/s. And after minor changes in the key, the NPCR of the ciphertext obtained by the DPEO algorithm exceeds 99.5%. In addition, its operation efficiency is excellent, reaching the stable entropy value in only 0. 52 s. In summary, the DPEO algorithm in the network link transport layer database security encryption system can combine high efficiency and excellent security performance.

Analysis and Implementation of a Frequency Synthesizer Based on Dual Phase-Locked Loops in Cesium Atomic Clock

The frequency synthesizer plays a crucial role in atomic clock technology. In this study, we demonstrate a direct microwave frequency synthesizer for a cesium atomic clock, employing frequency multiplication and a dual-phase-locked loop mode. A mathematical model of the frequency synthesis chain is established to estimate its performance. The phase-settling time and system stability are analyzed and studied in detail, and the obtained results are verified by experiments. An optimized realization of the frequency synthesizer shows that the phase-settling time can be adjusted within the range of 644.5 µs to 1.5 ms. Additionally, we measure the absolute phase noise values to be −63.7 dBc/Hz, −75.7 dBc/Hz, −107.1 dBc/Hz, and −122.5 dBc/Hz at 1 Hz, 10 Hz, 1 kHz, and 10 kHz offset frequencies, respectively.

Research on laser target dynamic tracking system with rotating polarization grating.

A micromechanical target tracking system based on polarization grating (PG) is designed to meet the conformal design of laser communication systems and to realize the lightweight and miniaturization of space laser communication networking. The rotating dual PGs are applied to the dynamic tracking of laser targets for the first time, the relationship between the target position and the dual polarization gratings (PGs) angles is defined, and the PG beam deflection multi-coordinate construction and decoupling are carried out. A dual PGs mathematical model was established, and a controller based on the dual PGs system loop was designed. After calibration and dynamic verification of the dual PGs, the unmanned aerial vehicle (UAV) tracking experiment is conducted for the first time, and the dual axis closed-loop tracking error of the dynamic target is within 300µrad (RMSE). The feasibility of dual PGs tracking formula, the feasibility of laser target fixed-point closed-loop control, and the dynamic closed-loop tracking performance are verified. In engineering applications, the dual PGs tracking system has guiding significance for realizing the lightweight and miniaturization of system integration, as well as the possibility to replace the traditional tracking control system.

Multiband bandpass filter with asymmetric dual‐band response based on metacell

AbstractThe impressive growth in present‐day wireless communication systems demands compact, low‐power, cost‐effective, planar multiband microwave devices to increase the speed of communication and reduce hardware requirements, which subsequently reduce the power requirement of the system. Accordingly, this article aims to design a multiband microstrip bandpass filter with asymmetric dual‐band response based on metacell. The proposed filter is designed for wide and narrow dual‐band responses with fractional bandwidths of 72% and 2.6%, respectively. For the first time in this article, a new application of metacell in the design of dual‐band filters is discussed. A folded asymmetric step‐impedance resonator and a novel metacell structure—Dual loop split ring resonators are used to obtain wideband and dual‐band responses, respectively. The proposed work discusses the design methodology, and analysis of metacell structure based on a quasistatic model and compares simulation results with experimental results. The proposed dual‐band filter presents an insertion loss (S21) of less than 1 dB and input reflection coefficient (S11) greater than 10 dB in both passbands centered at 3.3 and 5.7 GHz. The designed filter is suitable for wireless communication applications—Wireless Access in the Vehicular Environment.

Experimental study on the thermal performance of a dual compensation chamber loop heat pipe with dual vapor and condenser lines

Experimental study on the thermal performance of a dual compensation chamber loop heat pipe with dual vapor and condenser lines

A Self-Triggered Digitally Assisted Hybrid LDO with 110 ns Settling Time in 65 nm CMOS

This article presents a self-triggered digitally assisted hybrid low-dropout regulator (LDO). The proposed architecture uses an analog LDO for steady-state operation and a digital LDO to track large output current changes. The dual loop has a loop controller for coherent operation, and the digital loop is only triggered when there is a large load step. Therefore, the proposed LDO inherits some of the advantages of both parts. It achieves a high power supply rejection ratio (PSRR) from the analog part. The digital loop has a faster settling time and consumes less static power than the analog loop. In this design, the maximum load is 200 mA. For heavy load conditions, PSRR is −40 dB at 1 MHz. The quiescent current is 200 μA. The undershoot/overshoot with the corresponding settling time measured under a load current step of 200 mA/10 ns are 82 mV/89 ns and 112 mV/110 ns, respectively. The proposed LDO achieves a competitive 4.48 ps figure of merit. In the TSMC 65 nm process, the active area is approximately 0.027 mm2.

Hierarchical dual loop voltage and frequency control in stand alone microgrid with priority based intelligent load management

Hierarchical dual loop voltage and frequency control in stand alone microgrid with priority based intelligent load management

Versatile dual-channel loop-mediated isothermal amplification assay featuring smartphone imaging enables determination of fecal indicator bacteria in environmental waters

Rapid diagnostic assays are often a critical tool for monitoring water quality in developing and developed countries. Conventional testing requires 24–48 h for incubation, resulting in delayed remediation and increasing the likelihood of negative outcomes. In this study, we report a workflow for detection of E. coli, a common indicator of fecal contamination. Following large volume filtration, E. coli is then solubilized enabling the facile isolation and recovery of genetic material by a thin film microextraction (TFME) device featuring a polymeric ionic liquid (PIL) sorbent. Rapid recovery of pure nucleic acids is achieved using a PIL sorbent with high affinity for DNA to significantly increase mass transfer and facilitate adsorption and desorption of DNA. Downstream detection is performed by a versatile, dual channel loop mediated isothermal amplification (LAMP) assay featuring a colorimetric dye and a sequence-specific molecular beacon. A portable LAMP companion box enables consistent isothermal heating and endpoint smartphone imaging while being powered by a single 12-V battery. Programmable LEDs are switched from white or blue light to facilitate the independent imaging of the colorimetric dye or fluorometric probe following amplification. The methodology positively identified E. coli in environmental samples spiked to concentrations of 6600 colony forming units (CFU) per milliliter and 660 CFU/mL with 100% and 22% positivity, respectively.

An adaptive control strategy for grid-forming of SCIG-based wind energy conversion systems

One of the crucial issues in the expansion of isolated wind energy conversion systems (WECSs) is the design of a grid forming control structure that is robust to changes of the system’s operating point in the steady-state as well as transient conditions. This paper has addressed the voltage/frequency control of a local microgrid as well as flux and slip control of a squirrel cage induction generator that feeds the microgrid via a back-to-back converter in an isolated WECS. An adaptive nonlinear voltage control structure has been proposed for load side converter (LSC) consists of a constant frequency voltage regulator and a current controller based on the Lyapunov function method (LFM), which are connected in cascade. In an outer loop, the reference current of LSC is generated by the voltage regulator designated for maintaining the voltage/frequency of the microgrid. In an inner loop, the reference signals are robustly tracked by the current controller. In a novel reference frame that its angle difference with the stationary reference frame is determined by a dual loop DC link voltage controller, an LFM-based nonlinear flux controller is proposed for the machine side converter (MSC). Using the proposed flux control structure, in addition to maintaining the flux magnitude at a nominal value, by controlling the generator slip through adjusting the speed of the proposed reference frame, the power balance is established and the DC voltage is maintained at a pre-set value. The performance of the proposed controllers has been investigated through simulation in the MATLAB® software. The obtained results confirm the robustness and stability of the proposed control structure with respect to various disturbances and uncertainties.

An Output-Capacitor-Free Synthesizable Digital LDO Using CMP-Triggered Oscillator and Droop Detector

This article presents a synthesizable digital low-dropout regulator (DLDO) that precludes the use of an output load capacitor. For efficient regulation, the DLDO consists of fine and coarse loops that have different load conditions to operate. The dual loops are made of typical standard cells to improve the synthesizability. In the coarse loop, a comparator (CMP)-triggered oscillator is employed to generate a high-frequency clock signal without concerning the metastability in the CMP. In order to achieve a fast response to a voltage droop caused by load–current variation, a droop detector and latch-based drivers are exploited that are capable of compensating for a voltage droop asynchronously. The prototype of the DLDO was fabricated in 28-nm CMOS technology. A range of supply voltage is from 0.5 to 1.0 V with a 50-mV dropout voltage. Depending on a supply voltage, a maximum load current and a quiescent current are measured as 160-to-480 mA and 7.7-to-241 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> A, respectively. While a load current is increased from 20 to 450 mA with a 2-ns edge time, a 112-mV voltage droop and a 1.4-ns response time are achieved. Thanks to the synthesizability and the output-capacitor-free design, the DLDO occupies an 0.049-mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^2$</tex-math> </inline-formula> total area and offers 9.8-A/mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^2$</tex-math> </inline-formula> current density.

Current-Constrained Power-Angle Characterization Method for Transient Stability Analysis of Grid-Forming Voltage Source Converters

The necessity of limiting the output current of grid-forming (GFM) voltage source converter (VSC) has led to drastic deformation of its power angle characteristic (PAC), posing a great challenge to the transient synchronization stability (TSS) analysis. This current limitation associated TSS issue has been extensively studied in the context of the conventional dual loop controlled GFM VSC, while the analysis for the lately prevailing virtual admittance control (VAC) is less explored. To this end, this paper proposes the current-constrained (CC)-PAC method for TSS analysis of VAC-based GFM VSC. Based on the proposed CC-PAC, first, the TSS mechanism exclusive to VAC-based GFM VSC is revealed, and the impact of resistive and inductive virtual impedance is discussed. Then, the Lyapunov's direct method-based TSS assessment is rigorously achieved and performed by using the obtained CC-PAC, including the region of attraction (ROA) estimation and the critical clearing time (CCT) analysis. Finally, effectiveness of the CC-PAC along with its TSS analysis is thoroughly verified by PSCAD/EMTDC simulations.