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Current studies on the ball-on-plate (BoP) problem are mainly focused on platforms with a fixed base and use a vision system to detect the ball. However, relevant works on legged robots are not available, especially on six-parallel-legged robots using pure haptic information. This paper proposes a novel BoP motion planning method for six-parallel-legged robots walking on irregular terrain based on pure haptic information. First, a six-parallel-legged robot with seven six-dimensional force/torque sensors is introduced. Then, a complete model of the BoP system on the robot is built by considering the six-degree-of-freedom motion of the body. Further, a measurement model of the ball state based on pure haptic information is built, and a low-pass filter, lead compensator, and Kalman filter are applied to extract useful information from the noisy sensor data. An impedance controller is proposed to control the ball, and a novel motion planner with five sub-planners is introduced to address the problem of walking on irregular terrain. Finally, experiments are conducted on the prototype to validate the method. The results show that the method performs robustly when the robot traverses irregular terrains.

Granger causality tests are being supplanted by new methods such as the Lead‐Lag Ratio, particularly in finance where data arrives at random times and systematic sampling often produces spurious results. Existing approaches are insufficient; outside of block‐sampling using a bootstrap, the lead‐lag ratio has generally been assessed against a benchmark of 1 without regard for statistical significance. We use simulations to generate a response surface for the Lead‐Lag Ratio. Our modelled critical values are applied to reassess the findings of three previous studies of lead/lag relations between financial return series with high frequency data. Our response surface method proves to be a convenient and efficient alternative to using a bootstrap.

Background:Theintegrationof mobileroboticplatformsin humangaitanalysisoffers thepotentialtodevelop multiple medical applications and achieve new discoveries. The aim of this paper is to presenta first design and validation of a ROS-based mobile robotic platform for human gait analysis.Methods:During the design stage, the model identification and the configuration of the control lawwere performed. The design of the control law required the integration of a lead compensator and aFiltered Smith Predictor (FSP). During the validation procedure, the accuracy of the system to retrievekinematic gait data and the main descriptors of gait disorders was calculated with respect to theground truth of a Vicon system. For this purpose, one hundred gait recordings were processed thanksto the collaboration of twenty participants. The participants walked in a one-way straight line gait.Results:Results showed high correlation and low error rates mainly in joint excursions from sagittaland transverse planes.Conclusion:This gait analysis system demonstrated several advantages compared with the currentapproaches. The use of a mobile robotic platform allowed gait analysis in long tracking ranges andwithout space limitations. Furthermore, the design of a suitable control law allowed a smooth trackingof the person. This led to optimal results when assessing joint excursions.Significance:This system represents a cost-effective and non-invasive alternative that could be usedfor human gait analysis applications., The research leading to these results has received funding from RoboCity2030-DIH-CM, Madrid Robotics Digital Innovation Hub, S2018/NMT-4331, funded by “Programas de Actividades I+D en la Comunidad de Madrid, Spain” and co-financed by Structural Funds of the EU . The authors would like to thank Faculty of Physical Activity and Sports Sciences - INEF, UPM, for the use of Sports Biomechanics Laboratory. The authors also acknowledge Enrique Navarro Cabello and Javier Rueda for their contribution during the experimental stage.

Background: A recent study in Nature Climate Change shows that due to reduced human activities during the Coronavirus disease 2019 (COVID-19) pandemics, daily global emissions of carbon dioxide decreased by 17% from the average level in 2019. With the gradual recovery of economic activity and human energy consumption, the emissions of greenhouse gas and pollution would rise again. Green bonds are considered a crucial tool to release climate finance. The green bond market can act as an essential bridge between capital providers (i.e. institutional investors) and sustainable assets (i.e. renewable energy).This study is the first attempt to examine co-movement and the lead–lag relationship between green bonds and global and sector renewable energy stock markets in the time and frequency horizons. We apply continuous wavelet, wavelet coherence, and line and non-line causality approaches on data during the period 2010–2020, coincidentally including the COVID-19 pandemic.Results: (1) Green bonds and renewable energy markets show evidence of a similar pattern based on the wavelet power spectrum, which shows high price volatility at small and medium scales, especially during periods of turbulence and crisis. (2) The dynamic connection between green bonds and renewable energy returns is weak (strong) on the short (long) time-scale. However, on medium-term time scales, the dependence between them is significant only during turbulent periods, such as the European Sovereign Debt Crisis 2012 (ESDC) and the COVID-19 pandemic. (3) With regard to causality, our results show unidirectional and bidirectional linear (non-linear) causality at low and high frequencies. Moreover, our finding reveals the fact regarding the lead–lag relationship that, most of the time and frequencies, no one market necessarily dominates the other.Conclusion: Our findings provide several remarkable policies and practical implications for market regulators and investors. Institutional investors can benefit by including green bonds in their portfolios to decrease their climate change risk and improve their environmental, social, and corporate governance rating in the portfolio. Considering that the dependence between green bonds and renewable energy stock prices varies over various time scales, investors with different investment horizons should make diverse investment portfolio and hedging choices. The finding is also relevant for formulating green finance policies and supporting renewable energy investments. Policy decisions on the transition of energy to a decarbonized economy should consider the consequences for green bonds, which are also critical for the transition to a climate-resilient economy.

Installation of hybrid electrical power system is imperative to fulfil the escalated energy demand of consumers. Now a days, there is a propensity in using renewable energy resources due to its cost effectiveness. However, multiple generating systems and the switching between them creates serious problems regarding distortions and harmonics which needs to be eliminated. In this study, a grid connected hybrid system has been proposed with linear loads. The hybrid system works under the standard conditions of wind and temperature. System has been assessed by applying Newton Raphson method and efficiency has been improved by using lead lag compensator (LLC). ETAP software has been used for simulation purpose. The effectiveness of the electrical system is measured by considering the load intake and consumption.

The full-scale fatigue test of rotor blades is an important and complex part of the development of new wind turbines. It is often done for certification according to the current IEC (2014) and DNV GL AS (2015) standards. Typically, a new blade design is tested by separate uniaxial fatigue tests in both main directions of the blade, i.e. flapwise and lead lag. These tests are time-consuming and rather expensive due to the high number of load cycles required, up to 5 million. Therefore, it is important to run the test as efficiently as possible. During fatigue testing, the rotor blade is excited at or near its resonant frequency. The trend for new rotor blade designs is toward longer blades, leading to a significant drop in their natural frequencies and a corresponding increase in test time. To reduce the total test time, a novel test method aims to combine the two consecutive uniaxial fatigue tests into one biaxial test. The biaxial test excites the blade in both directions at the same time and at the same frequency, resulting in an elliptical deflection path of the blade axis. Using elliptical loading, the counting of damage equivalent load cycles is simplified in comparison to biaxial tests with multiple frequencies. In addition, the maximum loads in both main directions remain separated, while off-axis loading is introduced. To achieve such a test, specific load elements need to be arranged so as to equalize the natural frequencies of the test setup for both test directions. This is accomplished by adding stiffness or inertial effects in a specific direction. This work describes a new method to design suitable test setups. A parameterized finite element (FE) model of the test with beam elements for the blade represents the test setup. A harmonic analysis on the FE model can identify the load distribution and the test conditions of a specific test setup within seconds. An optimization algorithm that varies parameters of the model and searches for the optimal setup is then applied to the analysis. This approach allows the efficient determination of a test setup, suited to the predefined requirements. The method is validated by applying it to three different test scenarios for a modern rotor blade: (a) state-of-the-art uniaxial setups, (b) uniaxial setups including springs and (c) a biaxial setup. In conclusion, the resulting setups are evaluated in terms of test quality and efficiency.

Several active damping strategies have been proposed in the literature for grid-connected converters with LCL filter but there are not specific strategies for DFIG wind turbines. In this system, there is an interaction between the two converters of the back-to-back conversion structure, which must be properly modeled in order to design effective damping strategies for the LCL filter resonant poles. This paper proposes a robust active damping strategy for DFIG wind turbines with LCL filter that considers the special features of this system. In this technique the filter capacitor current is fed back through a lag compensator that adjusts the delay of the feedback loop to emulate a virtual impedance that has dominant resistive behavior in the range of possible resonance frequencies. It is shown that a similar damping of the LCL filter resonance is achieved when the strategy isimplemented in either of the two converters. This work was supported by the Spanish State Research Agency (AEI) under grants PID2019-110956RB-I00 /AEI/10.13039 and DPI-2016-80641-R.

Air conditioners (ACs) are widely considered as good candidates to provide operating reserve. Demand response rebound, i.e., the rebound peak of aggregate power, may exist when ACs are controlled by changing the set point temperature. The rebound peak during the recovery period, named lag rebound, may cause significantly higher demand than that prior to the reserve deployment event. The rebound peak during the reserve deployment period, named lead rebound, is rarely considered in previous researches but will constrain the duration time to a short period (e.g., 10 min), which greatly limits the utilization of ACs. This paper proposes an optimal sequential dispatch strategy of ACs to mitigate the lead–lag rebound, and thus realize flexible control of the duration time from minutes to several hours. To quantify the effects of lead–lag rebound, a capacity-time evaluation framework of the operating reserve is developed. On this basis, ACs are grouped to be dispatched in sequence to mitigate the lead–lag rebound. The co-optimization of sequential dispatch on the capacity dimension and time dimension forms a mixed-integer nonlinear bilevel programming problem, in which the consumers’ thermal comfort is also guaranteed. Case studies are conducted to validate the proposed strategy.

This paper presents modeling, simulation, and control of a novel teleoperated mechanism, where two nonisomorphic manipulators are used in one integrated system, with the purpose of usage in oil and gas industry in the future. Overall integration of the teleoperated system has been done in the master–slave configuration, where a stuart-type 6-DOF parallel manipulator is used as a master robot and a 6-DOF serial manipulator is used as a slave robot. Since the parallel manipulator has a closed-loop structure and serial manipulator is an open-loop structure, their work spaces are of completely different nature in terms of overall shape and size. A novel task-space mapping mechanism has been proposed in this work to integrate these two completely nonidentical manipulators. Damped least-squares (DLS) method is used for overcoming the singularity of proposed task-space mapping matrix. This paper also presents detailed dynamic modeling of the parallel manipulator along with comprehensive analysis of proposed novel control technique. The biggest benefit of using proposed integration mechanism is the fullest access of the complete cartesian task spaces of both the master and slave manipulators. This paper also proposes usage of lag compensator for the improved tracking performance. Multilevel control architecture with local actuator-space and joint-space controllers, for the parallel and serial manipulators, respectively, has also been presented in this work.

The lead-lag relationships between spot and futures markets are of great interest for academics. Previous studies neglect the possibility of nonlinear behaviors which may be caused by asymmetry or persistence. To fill this gap, this paper uses the MF-DCCA method and the linear and nonlinear causality tests to explore the causal relationships between natural gas spot and futures prices in the New York Mercantile Exchange. We find that spot and futures prices are positive cross-correlated, the natural gas futures can linearly Granger cause spot price, and there are bidirectional nonlinear causality relationships between natural gas spot and futures prices. Further, we explore the sources of nonlinear causality relationships, and find that the volatility spillover can partly explain the nonlinear causality and affect their cross-correlations.

In wind power system, low frequency oscillations are observed due to imbalance between mechanical input and electrical output. Hence, variable susceptance controllers are being adopted to mitigate these oscillations. However, improper modulation of control parameters also leads to system instability. Therefore, we propose an optimization methodology for mitigating low frequency oscillations in wind power generation system. To visualize our methodology, we use a lead-lag type variable susceptance controller for fixed speed induction generator (FSIG) based wind generation system. Then, we optimize gain and time constants of lead-lag controller using three optimization algorithms: particle swarm optimization (PSO), genetic algorithm (GA), and flower pollination algorithm (FPA). Later, we perform non-linear time domain simulation and quantitative analysis to find average fitness, standard deviation, run time, and iteration number for these optimization algorithms. Moreover, non-parametric statistical analysis, such as Kolmogorov–Smirnov and Wilcoxon signed-rank tests are employed for identifying statistically significant differences among these algorithms.

Repetitive control (RC) with linear phase lead compensation provides a simple but very effective control solution for any periodic signal with a known period. Multirate repetitive control (MRC) with a downsampling rate can reduce the need of memory size and computational cost, and then leads to a more feasible design of the plug-in repetitive control systems in practical applications. However, with fixed sampling rate, both MRC and its linear phase lead compensator are sensitive to the ratio of the sampling frequency to the frequency of interested periodic signals: (1) MRC might fails to exactly compensate the periodic signal in the case of a fractional ratio; (2) linear phase lead compensation might fail to enable MRC to achieve satisfactory performance in the case of a low ratio. In this paper, a universal fractional-order design of linear phase lead compensation MRC is proposed to tackle periodic signals with high accuracy, fast dynamic response, good robustness, and cost-effective implementation regardless of the frequency ratio, which offers a unified framework for housing various RC schemes in extensive engineering application. An application example of programmable AC power supply is explored to comprehensively testify the effectiveness of the proposed control scheme.

Electric power take-off system has gained significant popularity in automobiles and aircraft. The system requires a high-gain step-up converter to boost the voltage of the low-voltage batteries. A novel topology has been proposed for these applications. The output voltage requires good regulation during load changes. This paper presents the dynamic modeling of the converter using generalized averaging method. A small-signal model is developed by linearizing around the operating points. The analysis of system stability indicates that the system is stable at all operating points. The sensitivity of parameters such as leakage inductance and load resistance has been studied to analyze the effect of these parameters in the context of system behavior and the controller design. A dedicated controller has been designed, which includes a feedback controller to regulate the output voltage and a lead compensator to solve the potential instability issue brought by the right-half-plane zeros. It also includes a feedforward controller in its inner loop to eliminate the effect of the disturbance in the input voltage. Simulation and experimental results have been used to validate the system model and the proposed controller.

In process control industries, one of the major and serious problems is presence of overshoot on controlled variables. This paper deals with the elimination overshoot in step response by using conventional PID controller with cascading of lead compensator. The proposed cascade technique consists of inner loop with lead compensators and outer loop with PID controller. The processes industry consists of many control loops and most of the control loops are consists of PI and PID controller. The PI/PID controller is used in the control loop with unstable system, the time response is oscillatory due to gain margin and phase margin. The proposed idea is to use the cascade control principle to control the unstable system with cascaded PID and Lead compensator. The compensator is used to compensate desired phase margin value of system and then make use of the PID controller is to control the system with robust, reduced order response, and thus, suppressing the overshoot in time response. The validity of the proposed approach is verified through simulation for the level control of unstable biochemical reactor.

The objective of this study was to improve the power captured in heaving wave energy converters using a simple robust hierarchical control strategy (HCS). A HCS comprises a higher level controller (HLC) and a lower level controller (LLC). The HLC provides a reference velocity for the buoy, which is in-phase with the wave’s excitation force. The LLC follows the reference despite the uncertainties in the model. We propose a new HCS called bottom-up HCS (BU-HCS), where the LLC is designed before the HLC. The LLC is implemented using a feedback controlled system with a simple lead-lag compensator as its controller. The lead-lag compensator is designed using H ∞ theory with the objectives of maximizing the robustness and tracking properties of the LLC while minimizing the control force of the power take-off (PTO) device. A set of optimization problem is obtained for designing the parameters of the lead-lag compensator, which are solved using a genetic algorithm. The HLC in the BU-HCS provides the velocity reference, which satisfies a constraint on the control force and the PTO’s utilization index. The HLC is implemented by designing the value of an intrinsic resistance constant, which can be found using the Bode magnitude plot of a transfer function. Based on the plot, a look-up table for the intrinsic resistance constant is generated as a function of the significant height and the peak period of the wave. We tested the proposed method in various scenarios and its performance was compared with existing control techniques.

The fuel cells, as the recently emerged power sources, offer a number of unique benefits such as higher efficiency, lower environmental impacts, and suitable scalability. These merits are achieved ...

In order to improve the support capacity of the grid frequency for maximum power point tracking of wind turbines, a virtual synchronous generator is usually used to increase the rotational inertia of the system. However, when the parameters change and the load changes abruptly, it would cause the power oscillation problem. For suppressing the power oscillation problem, firstly, the influence of damping coefficient on power oscillation is analyzed by second-order virtual synchronous motor model. Secondly, a virtual synchronous machine control strategy with parameter adaptive ability is designed by using lead-lag link and fuzzy logic control algorithms. In addition, the introduction of lead-lag link improves the response speed of virtual synchronous machine. The simulation results of MATLAB/Simulink verify the effectiveness and feasibility of the designed control method.

In view of the contradiction between active power steady-state and dynamic characteristics regulation of VSG based on the existing first-order virtual inertia algorithm operating in grid- connected mode and multi-paralleled mode, a virtual inertia control strategy based on multi-stage lead-lag compensation is proposed in this paper. By cascading a multi-stage lead-lag link in the first -order virtual inertia forward channel, the control freedom of VSG grid-connected and paralleled system is increased, so that the zero and poles can be freely configured. Furthermore, a first-order lead-lag link is taken as an example to analyze its effect on the output active power steady-state and dynamic characteristics of VSG grid-connected system and paralleled systems. Through reasonable configuration of the second-order virtual inertia parameters, the system damping ratio can be increased and the power oscillation can be eliminated while its steady-state characteristics are not changed under the circumstance of a large inertia. Experimental results verify the effectiveness of the proposed strategy.

With the increased share of renewables in power generation grid tied multilevel Inverters find a greater use. The vector control scheme has been implemented in the reference frame rotating at synchronous speed based on the independent control of real and apparent flow of power from the inverter to the grid. The currents injected in to the grid are controlled with two current control loops, one for the direct axis and other for the quadrature axis. Here, a lag compensator is taken as a controller technique for grid interface inverter to mitigate the power quality issues. The Insulating Gate Bipolar Transistor has forms as semiconductor switch for the parallel connected Voltage Source Inverter. The switching control employs SPWM technique in which a high frequency carrier is modulates with sinusoidal wave of grid frequency. The mathematical model of the inverter and its operation for power quality improvement has been validate and represents by the simulation.

In the paper, the standard IEEE 10-generator 39-bus test system is simulated offline and also in real-time using an educational real-time simulator, called miniature full spectrum simulator (Mini-FSS). In a power system, the interactions between one another among the various generators, their excitation systems, and their automatic voltage regulators lead to low-frequency oscillations. Power system stabilizers (PSS) are used to damp out such oscillations. This paper reviews the design of PSS and implements the same on the test system considered. For the design of the stabilizer, a small signal model of the system is derived by modeling the machines using the 1.1 model and linearizing them about the operating point. With the stabilizer implementation, damping of the oscillations in terminal voltage, excitation voltage, and rotor angle difference is clearly observed. These are contrasted with those results without the stabilizer implementation. Dynamic response of the system to 10 percent step-change in terminal voltage reference is also studied. Computation time taken by the real-time simulator is also ascertained. The educational real-time simulator, which consists of 9 DSP processors for parallel computation, is found capable of simulating the 10-generator system in real-time with only one processor, completing the calculations in each computational step within $30 \mu \mathrm {s}$.

This paper realizes control of the motion of a swimming robot fish in order to implement an underwater robot fish aquarium. And it implements positional control of a two-axis trajectory path of the robot fish in the aquarium. The performance of the robot was verified though certified field tests. It provided excellent performance in driving force, durability, and water resistance in experimental results. It can control robot motion, that is, it recognizes an object by using an optical flow object-detecting algorithm, which uses a video camera rather than image-detecting sensors inside the robot fish. It is possible to find the robot’s position and control the motion of the robot fish using a radio frequency (RF) modem controlled via personal computer. This paper proposes realization of robot fish motion-tracking control using the optical flow object-detecting algorithm. It was verified via performance tests of lead-lag action control of robot fish in the aquarium.

The lead-lag power system stabilizer has several parameters to be optimized.In fact, the number of these latter increases with the number of generators constituting the multi-machine system.In this work, we propose anew approach of an adaptive and robust PSS; it achieves encouraging results by adjusting the gain using fuzzy logic and in the same time we use the same PSSs for each machine. In the first place, we could check that the gain is among the most critical parameters of the lead lag PSS. The parameters are globally optimized by the genetic algorithm, after that an expertise on the speed and the gain variations allow the value prediction according to the velocity deviation. To validate our results, a robustness test was made on a multimachine system IEEE (3 machines 9 bus), for different loads and the results showed good performance and robustness of the presented PSS.

In this paper a new control algorithm for position tracking of sinusoidal trajectories is introduced to improve the accuracy of a pneumatic actuator. A proportional valve is used to control the position of a rodded cylinder through a fuzzy logic (FL) approach with added velocity feedback (VF), f system lag compensator (LC) and friction compensator (FC). Parameters of the FL controller and the VF and FC compensators are tuned off-line manually. Parameters for the LC compensator are obtained by an on-line algorithm. Experimental results show that the proposed FL+VF+LC+FC controller is able to significantly improve tracking performance. The contribution of each component towards overall performance is carefully documented. The results compare favourably with the performance obtained with more advanced model-based algorithms as reported in the literature. The simpler non-model based nature of the controller together with the careful documentation of the algorithm and system performance, means that other researchers can readily evaluate the controller for their own applications.

This paper assesses the performance of feedforward controllers for disturbance rejection in univariate feedback plus feedforward control loops. The structures of feedback and feedforward controllers are confined to proportional-integral-derivative and static-lead-lag forms, respectively, and the effects of feedback controllers are not considered. The integral squared error (ISE) and total squared variation (TSV) are used as performance metrics. A performance index is formulated by comparing the current ISE and TSV metrics to their own lower bounds as performance benchmarks. A controller performance assessment (CPA) method is proposed to calculate the performance index from measurements. The proposed CPA method resolves two critical limitations in the existing CPA methods, in order to be consistent with industrial scenarios. Numerical and experimental examples illustrate the effectiveness of the obtained results.

In this paper, an anti-windup design problem for a model predictive control system is studied. The plant is assumed to be stable. First, we propose the structure of an output feedback model predictive controller with an anti-windup compensator. Then we show a design method of the anti-windup compensator that guarantees closed-loop stability and improves the transient response. The design problem of the anti-windup compensator is reduced to a linear matrix inequality (LMI) optimization problem. Further, it is shown that there always exists an anti-windup compensator that ensures global asymptotic stability. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

In this paper we introduce a novel benchmark problem to study the control of magnetic needle with two degrees of rotational freedom in a uniform magnetic field. Magnetic needle in an external magnetic field has stable and unstable equilibrium points, which depends on it's orientation. Our idea is to control the magnetic needle near it's unstable equilibrium point. Dynamics of the system is derived using Lagrangian energy based technique. The nonlinear system dynamics are linearized at unstable equilibrium point and the controllers are designed for this linear system, and the same controllers are applied to nonlinear system. The difference in tracking performance for linear and nonlinear system is observed using PD, PID, lead, lead lag compensators and state feedback, feed forward integral controller and H ∞ , quantitative feedback controllers. Further, control effort for all the above controllers are computed.

With the continuous expansion of wind farm clusters, the multi-terminal modular multilevel converter based high voltage direct current (MMC-HVDC) transmission has been employed for wind power delivery. To improve the control flexibility, dynamic voltage adjustment speed and rationality of power allocation, various coordination control methods have been recently investigated in multi-terminal MMC-HVDC transmission system. An attempt is made in this paper to contribute to the optimization of coordination control in the multi-terminal MMC-HVDC system connected to wind farms. Based on the analysis of DC voltage, power deviation and droop coefficient, an improved droop control strategy with adjustable coefficients is first proposed and thereby applied to multi-terminal MMC-HVDC transmission system with wind farm clusters. Arguably, the droop coefficient correction should be an effective method for optimizing power allocation and reducing DC voltage deviation between the receiving converters. In addition, a lag compensator is introduced to improve the response speed of the inner loop controller when the improved droop control is adopted. Furthermore, the influence of droop coefficients on the stability of the control system is discussed, and the dynamic response of the improved control system is also analyzed under the different droop and time coefficients, which can provide guidelines for the control optimization of multi-terminal MMC-HVDC system. Finally, a model of a five-terminal MMC-HVDC transmission system is built based on the RT-LAB simulator, and the simulation results show that the proposed method can not only optimize the voltage control and power allocation, but also improve the system response speed.

In the hybrid energy storage system of electric vehicles (EVs), supercapacitors (SCs) are configured to supplement high frequency power loads to reduce battery strains. Continuous supply and quick response to power load through bidirectional power control is of great importance to attain power balance and keep the stability of bus voltage. In this paper, we propose a reference modulation based power management strategy to tackle this problem. Specifically, an adaptive SCs reference current regulation is designed to maintain sustainable power supply for SCs. A discrete lead compensator based reference smoothing control technique is integrated in to bottom layer control in order for quick transient response to stochastic power demand. With the designed SCs current regulation and reference smoothing technique, we aim to reduce the fluctuation of bus voltage. US06 driving cycles are applied in simulation and experiment to verify the effectiveness of the proposed approach.

Investor sentiment has a significant role in driving stock prices. Although many previous studies show that investor sentiment in social media can be used to predict stock price movements, there are two things that still need further investigation. The first one is related to the attention of investors that affect the ability to predict the movement of stocks price and its interaction with investor sentiment. The second one is related to the effect of the lead-lag relationship between investor sentiment, investor attention, and stock return. Therefore, the purpose of this research is to understand the effect of the lead-lag relationship between the three variables as well as the interaction between investor sentiment and investor attention in predicting the movement of stock prices. The steps taken to answer the research problem are to measure investor sentiment based on comments in social media Stockbit, measure investor attention based on search volume obtained from Google Trend, and then test the effect of lead-lag relationship and interaction between variable using Granger causality analysis and vector autoregression. Test results show that investor sentiment in Indonesia is a reaction from stock returns, not the cause, so it cannot be used to predict stock price movement. Also, investor attention measured by search volume in Google Trend cannot be used to predict stock price movement either. There are four reasons on why investor sentiment has no significant effect on stock return, which is the speed of information diffusion on the stock price, data source used, size of stock capitalization tested, and selection of investor sentiment measurement method. Furthermore, there are two reasons on why investor attention has no significant effect on stock return, which is related to stock capitalization size tested and google search volume that does not reflect investor attention. The insignificant effects of investor sentiment variable and investor attention to stock returns cause the interaction between the two not significant.

This paper presents a proportional–integral–lead (PI–lead) compensator design based on frequency domain specifications to regulate the output voltage of pulse width modulated dc–dc buck converter. In this design, the parameters of PI–lead compensator are tuned in two parts such that the PI section improves the steady-state response, whereas lead section improves the transient response of the uncompensated system. Further, the detailed performance analysis is carried out in order to obtain optimal value of phase margin and gain crossover frequency for dc–dc buck converter. Finally, this control strategy is verified through MATLAB/Simulink simulation and is implemented on an experimental setup using dSPACE DS1104 digital signal processor. The experimental results validate the simulation results and indicate the robustness of the compensator under wide variations in input voltage, load current and desired output voltage.

Power system is often vulnerable to low frequency electromechanical oscillations due to the interconnected configuration. A common lead-lag controller is used for one of the FACTS devices known as Thyristor Controlled Series Compensator (TCSC) as supplementary controller for damping purpose in order to improve transient stability and power oscillation damping of the system. As Bees Algorithm (BA) optimized the parameters of the TCSC lead-lag controller, thus its named is TCSC-BALL. In this study, the optimization problem is formulated as a constrained optimization with the main objective is to move the system eigenvalues to the left as far as possible in order to improve the system stability. Then, the system is simulated in MATLAB by using The Phillips-Heffron model for single machine infinite bus (SMIB) with responses of increases in mechanical power at t=1 second. The performance is observed in terms of electromechanical eigenvalues position on s-plane and damping responses of low-frequency oscillations where the system implemented with the TCSC-BALL controller given better results as compared to the system without and with the inclusion of conventional Power System Stabilizer (CPSS).

According to the leading models in modern finance, the presence of intraday lead-lag relationships between financial assets is negligible in efficient markets. With the advance of technology, however, markets have become more sophisticated. To determine whether this has resulted in an improved market efficiency, we investigate whether statistically significant lagged correlation relationships exist in financial markets. We introduce a numerical method to statistically validate links in correlation-based networks, and employ our method to study lagged correlation networks of equity returns in financial markets. Crucially, our statistical validation of lead-lag relationships accounts for multiple hypothesis testing over all stock pairs. In an analysis of intraday transaction data from the periods 2002--2003 and 2011--2012, we find a striking growth in the networks as we increase the frequency with which we sample returns. We compute how the number of validated links and the magnitude of correlations change with increasing sampling frequency, and compare the results between the two data sets. Finally, we compare topological properties of the directed correlation-based networks from the two periods using the in-degree and out-degree distributions and an analysis of three-node motifs. Our analysis suggests a growth in both the efficiency and instability of financial markets over the past decade.

This paper proposes a new robust decentralized power oscillation dampers (POD) design of doubly-fed induction generator (DFIG) wind turbine for damping of low frequency electromechanical oscillations in an interconnected power system. The POD structure is based on the practical 2 nd -order lead/lag compensator with single input. Without exact mathematical model, the inverse output multiplicative perturbation is applied to represent system uncertainties such as system parameters variation, various loading conditions etc. The parameters optimization of decentralized PODs is carried out so that the stabilizing performance and robust stability margin against system uncertainties are guaranteed. The improved firefly algorithm is applied to tune the optimal POD parameters automatically. Simulation study in two-area four-machine interconnected system shows that the proposed robust POD is much superior to the conventional POD in terms of stabilizing effect and robustness.

Lag-lead compensators are well known in automatic control engineering. They have 3 or 4 parameters to be adjusted (tuned) for proper operation depending on the compensator order. The frequency response of the control system or the root locus plot are traditionally used to tune the compensator in a lengthy procedure. A selected very slow second-order process has a time response to a unit step input of 150 seconds settling time is controlled using a first-order lag-lead compensator (through simulation). The lag-lead compensator is tuned by minimizing the sum of square of errors of the control system using MATLAB. Four functional constrains are used to control the performance of the lag-lead compensated control system. The result was reducing the settling time to only 0.666 seconds. The steady-state characteristics of closed-loop control system using the first-order lag-lead compensator were excellent. It was possible reduce the steady-state error to less than 0.01 using the tuned first-order lag-lead compensator.

For a classic PLL with square waveform signals and lead-lag filter for all possible parameters lock-in range is computed and corresponding diagrams are given.

In this paper, a small-signal dynamic model of a single-machine infinite-bus (SMIB) power system that includes IEEE type-ST1 excitation system and PSS based on transfer fu¬n¬c¬¬tion structure is presented. The changes in the operating co¬n¬dition of a power system on dynamic performance have been exa¬m¬ined. The dynamic performance of the closed-loop system is ana¬lyzed base on its eigenvalues. The effectiveness of the par¬a¬m¬e¬t¬ers changes on dynamic stability is verified by simulation res¬u¬l¬ts. Three types of PSS have been considered for analysis: (a) the derivative PSS, (b) the lead-lag PSS or conventional PSS, and (c) the proportional-integral-derivative PSS. The objective fu¬nc¬t¬i¬o¬n is formulated to increase the dam¬¬ping ratio of the electromechanical mode eigenvalues. Simu¬la¬tion results show that the PID-PSS performs better for less ov¬e¬r¬shoot and less settling time comp¬ared with the CPSS and DPSS un¬der different load ope¬ration and the significant system pa¬r¬am¬eter variation conditions.

Capacitor-current-feedback active damping method is commonly used in LCL-filtered grid-connected inverters, which attenuates the resonance peak by emulating a virtual resistor in parallel with the filter capacitor. Taking the digital control delay into account, the emulation component becomes frequency-dependent, and it will turn negative when the filter resonance frequency becomes higher than one-sixth of the sampling frequency, resulting in the inconsistent stability requirement. Due to the variation of grid impedance, the filter resonance frequency will vary in a wide range, and the inconsistent stability requirement may occur, which will pose a challenge to the inverter stability. In this paper, the stability of digitally controlled LCL-filtered inverter is studied first, and a phase lag compensator is introduced to ensure the stability requirement keeps consistent even if the filter resonance frequency reaches the Nyquist frequency. Thus the stability-robustness of the inverter to the grid impedance variation is improved. Finally, the validation of the proposed compensation method is verified by simulation and experimental results.

This paper compares lead compensation and droop control of a 10MW lithium-ion based battery energy storage system (BESS) designed to maintain load frequency control (LFC) by dispatching regulating reserves of active power to a 91MW test section of the Maui, Hawaii island grid model with wind generation of 30MW. The test section is part of an existing larger Maui grid model developed by General Electric in Siemen's Power System Simulator for Engineering, and the BESS model is based on Electric Power Research Institute's CBEST battery model. Performances of the two controllers are compared to minimize the deviations in grid frequency caused by wind power variations and loss of generation. The results show using the BESS to provide LFC via lead compensator caused a significant reduction in frequency volatility and the magnitude of the frequency deviations in comparison to a microgrid without a BESS and using the BESS to provide traditional droop control. The advantage of the LFC over Base Case (no BESS) and the Droop Control case (Case 2) is that is more effective at reducing the frequency deviation caused by a disturbance on the microgrid.

Goal. The aim of this paper is to conduct a comprehensive comparative analysis between five different controllers for a drug infusion system in total intravenous anesthesia (TIVA) administration. Methods. The proposed method models a dilution chamber with first order exponential decay characteristics to represent the pharmacokinetic decay of a drug. The dilution chamber is integrated with five different control techniques with a simulation-based comparative analysis performed between them. The design process is conducted using MATLAB SISOTOOL. Results. The findings show that each controller has its own merits and demerits. The results generated using MATLAB signify and confirm the effectiveness of PI and cascaded lead controllers, with cascaded lead controller as the best control technique to automate and control the propofol delivery. Conclusion. In this paper, different control techniques for measurement-based feedback-controlled propofol delivery is confirmed with promising results. Significance. The comparative analysis showed that this drug infusion platform, merged with the proper control technique, will perform eminently in the field of total intravenous anesthesia.

With the improvement of performance in the ultra-precision manufacturing engineering, the requirements for vibration isolation have become more stringent. In order to obtain a wider effective bandwidth and a higher performance of a multi-DOFs active vibration isolation system (AVIS), active hybrid control (AHC) technology is applied in this paper. AHC technology comprises a feedback active control (FBAC) technology and a feedforward active control (FFAC) technology. Absolute velocity feedback is employed to establish a sky-hook damping technology in FBAC technology. Velocity feedforward of base platform is adopted to build a lead-lag phase compensation (LLPC) technology in FFAC technology. Further, a coordinate vector conversion from unit level to system level is mentioned to describe the dynamic characteristic of the six DOFs AVIS applied in the ultra-precision field. And with the assistance of the transformed coordinate vector, the dynamic model of system level is built. Based on the establishment of the dynamic model and the research of AHC, an experimental platform which constitutes three vibration isolators and a real-time active control system is set up. The experimental results indicate that the amplitude of the resonant peak is further reduced significantly, compared to the general feedback control. And simultaneously active effective bandwidth is extended. AHC technology with sky-hook damping algorithm and LLPC control algorithm is verified to be more effective.

Recently, a variety of differential power-processing (DPP) architectures have been shown to improve the efficiency of photovoltaic (PV) systems. This paper proposes a simple control strategy for the isolated-port DPP architecture, and provides a comprehensive stability analysis for this system. The proposed controller drives the duty-cycle of the differential submodule integrated converters (subMICs) in proportion to a voltage difference between the submodule and the isolated-port. This method requires no additional sensing, complex processing, or communication between subMICs, and is therefore well suited for low-cost integrated hardware solutions. Stability of the resulting high-order nonlinear system is analyzed both in the time and frequency domains. A decoupled model is developed that reduces the high-order system dynamics to a 1-D control loop, which allows stable, well-behaved responses using a proportional or a lag compensator. Experimental results for a 72-cell PV module with three subMICs verify static and dynamic operation, and show that overall PV module efficiency exceeds 99% with no shading, and is higher than 96% under significant (50%) shading.

The paper presents the issue of power control law synthesis, in the case of a large wind system that operates under full-load regime, based on dynamic properties details in frequency domain. Solving this problem involves two phases: the establishment of a linearized model as faithfully as possible in various operating points of the full-load region, and synthesis of the power controller, considered with classic structure, taking into account frequency particularities of the obtained linearized model. Obtained linear model of the controlled process is of order 16 and encloses subsystems for tower fore-aft oscillations damping, and for drive-train torsion oscillations damping. The designed controller contains a PI component and a lag compensator for dynamic correction at high frequencies. It is known that the main features of wind system dynamics generated by the interaction of wind–tower–blade ensemble cause a gap in the gain characteristic of the model and complex conjugate zeros, which can move between right and left half-planes, depending on the average wind speed value. Consequently, for control law synthesis an interactive frequency solution is adopted. This is “transparent” in relation to particularities induced by wind–tower–blade interaction. This solution allows evaluation of the extent to which control law is affected by the subsystem for tower oscillations damping. Given the strong dependence between the model and the mean wind speed value, a gain scheduling control law is designed. At different values of average wind speed, controller synthesis is performed in two ways: one applying the desired values to the stability reserve, and the other requiring the minimization of a performance criterion, aimed at reducing mechanical stress, while the controller parameters are kept in an area that ensures admissible values to the stability reserve. This second way allows obtaining a solution for designing a simple classic controller, dedicated to large wind turbines, to which may be imposed requirements for mechanical fatigue mitigation. The proposed solutions are backed by numerical results obtained through numerical simulation.

As the modern wind turbines (WTs) become larger in size, the structural loads experienced by the WTs increase dramatically, which would shorten the working life of the WTs and increase the maintenance cost. To mitigate such problem, this study proposes a non-linear pitch control strategy including tower load reducing objective for the WTs operating in the above-rated wind speed region. The proposed non-linear controller consists of a rotor speed regulator, a tower oscillation damper and a lead compensator. The rotor speed regulator and tower oscillation damper are designed separately based on inverse system method, which is a powerful tool in solving the control problem of non-affine non-linear system. The lead compensator is utilised to compensate for the phase lag of the pitch angle command caused by the pitch actuator. Furthermore, light detection and ranging (LIDAR) preview measurements are introduced to provide wind information for the proposed controller in order to improve its control performance. The simulation results with the aero-elastic model of fatigue, aerodynamics, structures and turbulence (FAST) show that, the proposed non-linear controller outperforms the baseline gain-scheduled proportional-integral controller. The proposed non-linear controller can work well in the whole above-rated wind speed region, and is easy to implement for application.

According to the characteristics of the internal model control and feed-forward control and Combining the both advantages, the compound control system of the internal model add feed-forward compensator was designed. In order to improve the dynamic performance of the control system, online identification method is adopted to establish the internal model. The designs of the internal model controller and feed-forward compensator were detailed instructions. The simulation shows that the compound control system have not only good dynamic performance, high tracking precision and strong anti-jamming capability, but also have the change of system parameters with strong robustness.

Uncertainties in power systems, such as intermittent wind power, generating and loading conditions may cause the malfunction of power system stabilizing controllers, which are designed without considering such uncertainties. To enhance the robustness of stabilizing controllers against system uncertainties, this paper proposes a new coordinated robust control of doubly fed induction generator (DFIG) wind turbine equipped with power oscillation damper (POD) and synchronous generator installed with power system stabilizer (PSS) for stabilization of power system oscillations. Without the difficulty of mathematical representation, the inverse output multiplicative perturbation is used to model system uncertainties. The structure of POD and PSS is specified as a practical second-order lead/lag compensator with single input. The parameters optimization of POD and PSS is conducted so that the stabilizing performance and robustness of POD and PSS are augmented. The improved firefly algorithm is applied to solve the optimization problem and achieve the POD and PSS parameters automatically. Simulation study in the modified IEEE-39 bus New England system included with DFIG wind turbines ensures that the robustness and stabilizing performance of the proposed coordinated DFIG with POD and PSS are much superior to those of the conventional DFIG with POD and PSS under various severe disturbances and system uncertainties.

This paper proposes a design of Specification Oriented Compensator (SOC) with a Proportional Integral Derivative (PID) controller for Load frequency Control (LFC) in a thermal power system. The phase margin which is derived from the computationally tuned response of PID controller is considered as a desirable specification and it is used to design the compensator. The different structures of compensator like lead, lag and lead-lag were first simulated in a single area power system and better results are found in Specification Oriented Lead Compensator (SOLC). The simulation study of two area thermal power system with SOLC is then performed and their frequency deviation and tie-line power deviation characteristics are compared with conventional PID controller, Integral controller and also with a non controller system. The Integral Absolute Error (IAE) and Integration Time Absolute Error (ITAE) are considered as performance indices to scrutinize the system robustness. The simulation studies clearly reveal the superiority of the proposed SOLC with PID controller over others in way of enhanced system transient response, improved the stability and robustness of the system. All the simulations in this paper are performed using Matlab software.

In this article, a design method for a PID controller is proposed based on IMC principles for control of open loop integrating and unstable first-order processes with time delay. The design is based on H2 optimal closed-loop transfer function for set point changes and step input disturbances. The method has one tuning parameter, and systematic guidelines are provided for the selection of this tuning parameter based on peak value of the sensitivity function. The performance of the designed controller is verified on various integrating and unstable processes, and it is observed that nominal and robust control performance is achieved with the proposed design method. Improved closed-loop performance was obtained when compared to other methods recently reported in the literature. Further, the proposed method provides good closed-loop performance even when there are large uncertainties in the process parameters.

The original idea of antiwindup controller design of equivalent separated-integartor controller structure for phase-lead-lag controller is presented in the paper. The idea is competitive to antiwindup for PID controller which is frequently applied in industry. Thus, mature approach of antiwindup for PID controller can be adopted in solving windup problems in phase-lead-lag controller. From equivalent model and especially from performed simulations, it is seen that the presented solution eliminate the windup.