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The study of lead–lag relationship between stock index and stock index futures is of great importance for its wide application in hedging and portfolio investments. Previous works mainly use conventional methods like Granger causality test, GARCH model and error correction model, and focus on the causality relation between the index and futures in a certain period. By using a non-parametric approach—thermal optimal path (TOP) method, we study the lead–lag relationship between China Securities Index 300 (CSI 300), Hang Seng Index (HSI), Standard and Poor 500 (S&P 500) Index and their associated futures to reveal the variance of their relationship over time. Our finding shows evidence of pronounced futures leadership for well established index futures, namely HSI and S&P 500 index futures, while index of developing market like CSI 300 has pronounced leadership. We offer an explanation based on the measure of an indicator which quantifies the differences between spot and futures prices for the surge of lead–lag function. Our results provide new perspectives for the understanding of the dynamical evolution of lead–lag relationship between stock index and stock index futures, which is valuable for the study of market efficiency and its applications.

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.

This paper investigates whether lead–lag patterns exist between small and large size portfolios constructed from stocks traded in the Athens Stock Exchange (ASE). We examine this relationship in both the short-run (by using the correlation-based approach of Lo and MacKinlay, 1990 and the generalised impulse response analysis by Pesaran and Shin, 1996 , Pesaran and Shin, 1998 ) and the long-run by employing the cointegration-based methodology of Kanas and Kouretas (2005) . Furthermore, upon identifying that cointegration exists we then use the estimated error correction models (ECMs) to obtain out-of-sample forecasts of small-firm portfolio returns and it is shown that these ECMs have superior forecasting performance relative to models without the error correction terms. Therefore, we were able to provide a richer exploration of the lead–lag relationships than the one obtained by standard autocorrelation and cross-correlation analysis and vector autoregression analysis. The main finding of our analysis is that a lead–lag effect between small and large size portfolios was established in both the short-run and the long-run for the Athens equity market.

This paper analyzes the lead-lag relationships between construction investment and GDP at business-cycle frequency by the tests of Granger causality and the impulse responses in the framework of the vector autoregression, using the annual Japanese data. The analysis find that private construction investment tends to lead GDP, not vice versa, in the Granger sense and is of value in predicting the course of GDP one year ahead. Government construction investment, on the other hand, tends to lag GDP.

In this study, a novel lead and lag type compensator circuit is proposed using a single active component, namely, the current feedback operational amplifier (CFOA). The proposed circuit has only one CFOA, two grounded resistors and two grounded capacitors. The input impedance of the proposed compensator is designed to be high whereas the output impedance is low. In terms of input and output impedance values, the proposed topology is suitable for a cascade connection with the voltage-mode structure not requiring buffer circuits, both at the input and output of the circuit. Moreover, the proposed circuit offers the advantage of controlling the poles and zeros orthogonally. The non-ideal effects depending on the active component are also presented in the paper. The commercially available AD844 integrated circuit component was used as the CFOA component in the proposed lead and lag compensator circuit and circuit simulations were performed using PSpice. Moreover, the electrical performance of the circuit was demonstrated by experimental studies. The achieved theoretical, simulation and experimental results are given with a comparison. Finally, a closed-loop control system application was given using the proposed compensator circuit and the operation of the circuit was demonstrated with PSpice simulations.

In the permanent magnet synchronous generator (PMSG), the DC bus voltage fluctuates up and down under the influence of the load and power grid, which greatly affects the safe and reliable work of PMSG. In order to suppress the wide range fluctuation of DC bus voltage under disturbance and enhance its anti-disturbance performance, an optimized DC bus voltage control strategy is proposed by using the improved linear active disturbance rejection control (LADRC) in the voltage outer loop. By considering factors, such as load disturbance and grid voltage mutation as the total disturbance of the system, the improved reduced-order linear expansion state observer (RLSEO) is used to estimate and compensate the total disturbance, which greatly improves the stability of DC bus voltage. Firstly, the mathematical model of grid-side converter is established. On this basis, the LADRC control based on RLESO is designed, which reduces the phase lag of the linear extended state observer (LESO) and enhances the disturbance observation accuracy of the system. Then, a lead lag correction link is added to the total disturbance channel of RLESO to reduce the noise amplification effect of RLESO. Finally, the frequency domain characteristic analysis and stability proof of the improved LADRC control strategy are carried out. The simulation results show that the control strategy proposed in the article has a better control effect on the DC bus voltage.

Fractional-order lead/lag compensator realizations, using Operational Transconductance Amplifiers as active blocks, are presented in this paper. Two different types of fractional-order transfer functions, derived from the integer-order lead/lag compensator transfer function, are used to describe the behavior of the fractional-order compensator. Both types are approximated using the Pade approximation tool, and are expressed by the same form of rational integer-order transfer function. This means that both types can be implemented using the same active core, which is an important advantage from the design versatility point of view. From the design flexibility point of view, the attractive feature is that both types offer electronic adjustment of their characteristics through the appropriate tuning of the DC bias currents. Simulation results, derived using the Cadence IC design suite and the design kit of the Austria Mikro Systeme 0.35 μ m CMOS process, are used for evaluating the performance of the presented designs.

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 this proposed work, a substantial comparative performance optimisation has been established between the PI, lead, lead-lag and fuzzy logic controllers towards the closed loop control strategies of a simplified permanent magnet synchronous motor (PMSM) drive. By the introduction of sinusoidal pulse width modulation (PWM) control strategy, it is expected that the nature of armature current would be nearly sinusoidal and generated torque ripples will be lesser. In this proposed structure of a PMSM drive, the speed reference has been incorporated with a speed controller to fortify that the exact speed of the proposed motor match with the base speed with null speed error. The overall structure of the PMSM drive is separated into two loop control structure, inner current loop and outer speed loop. All the necessary performance indices of the proposed PMSM drive system are tested in a MATLAB/Simulink environment. Moreover, the performance of a fuzzy logic speed controlled PMSM drive as compared to all classical controllers provides better dynamic as well as steady state performance with reduced torque ripples. Therefore, the entire performance of the proposed simplified PMSM drive in closed loop control strategy is executed and efficacy of controllers is resolved under various operating conditions. Hence, the superiority of intelligent speed controller (fuzzy logic controller) for this proposed PMSM drive model over all classical controllers is validated and optimised for high performance applications. Finally, an auto-tuning control strategy for the fuzzy intelligent speed controller is also proposed for optimal operation of the drive system.

In this article, design of PID controller using a modified internal model control (IMC) filter for right half plane (RHP) pole process with dead time is proposed. To possess H2 optimal behaviour, the derived IMC controller minimises the integral square error (ISE) for step input disturbances by defining the Blaschke product of unstable poles of the specific input and the model. Then it is converted into a single feedback loop controller as either PID or PID with first order filter on the basis of proposed underdamped IMC filter to improve the integral action and thereby providing fast response which is not feasible with critically damped filter. Maclaurin series approximation is used to design PID controller and Pade's approximation is used to design PID with first order lead lag filter. Various first order plus dead time (FOPDT) examples are taken and simulation is executed on diverse unstable processes and compared with some of the developed methods available in the literature. The two proposed controllers provide improved responses with respect to both nominal and perturbed conditions. The robustness studies have also been carried out for uncertainties in the plant dynamics and it is apparent that the proposed tuning method is robust.

Twin rotor system is a laboratory setup resembling a simplified helicopter model that moves along both horizontal and vertical axes. The literature on control of twin rotor systems reflects a good amount of research on designing PID controllers and their extensions considering several aspects, as well as onsome nonlinear controllers. However, there is almost no previous work on design of lag-lead type compensators for twin rotor systems. In this study, by considering this open research problem, lag and lead type compensators are designed and then experimentally verified on the twin rotor system. Specifically, first, lag and lag-lag compensators are designed to obtain a reduced steady state error as compared with proportional controllers. Secondly, lead compensation is discussed to obtain a reduced overshoot. Finally, lag-lead compensators are designed to make use of their favorable properties. All compensators are applied to the twin rotor system in our laboratory. From experimental studies, it was observed that steady state error was reduced when a lag compensator was used in conjunction with a lead compensator.

Recently, Grasshopper optimization algorithms (GOA) and Whale optimization algorithm (WOA) technique have significant consideration among different meta-heuristic optimization techniques. GOA is a newly proposed nature-inspired algorithm based on social behavior of grasshopper. The WOA technique is also comparatively modern meta-heuristic method, which mimics the behavior of humpback whales. Both the optimization techniques are popular in industry and science mainly because of their simplicity, avoidance of local optima and gradient free mechanism. These two methods are assumed to discover an appropriate solution considering a given objective work. The major goal of this controller design is to increase the stability of power system. Here, both GOA and WOA techniques are employed to optimize the parameters of the designed static synchronous series compensator (SSSC) controller with power system stabilizer (PSS). The proposed conventional lead-lag SSSC controller with PSS are optimized by using both GOA and WOA optimization techniques and tested under single-machine infinite bus system. At last, the simulation results of both GOA and WOA techniques are verified by considering different loading conditions.

Over the last decade, numerous control schemes have been proposed by researchers for quasi Z source inverter (qZSI) to provide fast dynamic response and good transient performances. This paper proposed a novelty and an effective tuning method of dual-loop controller based on lead compensator and proportional (P) controller for single-phase qZSI to ensure reliable DC-link power regulation. Specifically, lead compensator and P controller act as voltage control and current control loop, respectively, to generate the desired shoot-through duty cycle feeding towards the unipolar carrier based pulse width modulation (CB-PWM). The lead compensator contributes to move the system poles from the left to the right half of the s-plane while the P controller damps any high frequency oscillation occurrence caused by the newly sited complex conjugate pole pair. To demonstrate the effectiveness and the feasibility of the proposed controller, the qZSI is utilized as a static synchronous compensator (STATCOM) system to provide reactive current compensation at the point of common coupling (PCC). All simulation models and results which documented in this paper are carried out using MATLAB/Simulink software.

If the Low-frequency oscillations including Local and Inter-area Mode in power systems are not properly damped out, they can cause critical effects, including wide-area outage. In order to damp out these oscillations, the PSS (Power System Stabilizer) of each synchronous generator is typically used. This, however, cannot damp out inter-area oscillations. Although research on damping inter-area oscillations is conducted to resolve the mentioned problems, the Lead Lag Controller for damping the oscillations used in FACTS (Flexible AC Transmission System) devices including VSC (Voltage Source Converter) has limitations in that it is a linear controller designed at a linearized Power System models so there are some limitations incurred by the variable and unpredictable power system states, so that fixed controller parameters cannot properly damp out these oscillations. Meanwhile, the AI (Artificial Intelligence) techniques including supervised learning, unsupervised learning, and reinforcement learning are applied in various engineering fields to overcome a lot of nonlinear problems like those of power systems. In this paper, the ANN (Artificial Neural Network) controller, a kind of AI controller, was used to damp out inter-area oscillation at different power system operating conditions, after which the results were analyzed.

It is desirable for a dual-stage actuated (DSA) magnetic disk drive servo system to achieve fast and accurate read/write (R/W) head positioning. In the present study, we propose a DSA control scheme to improve the head positioning performance. The primary coarse actuator voice coil motor (VCM) is controlled by a notch filter and a lead compensator to facilitate large motion. The secondary micro-actuator (MA) is controlled by a feedback control approach called integral resonant control (IRC) in series with a notch filter to achieve rapid and high-precision head positioning. The proposed control scheme is examined through a simulation example.

If the Low-frequency oscillations in power systems are not properly damped out, they can cause critical effects, including wide-area outage. In 1996, Low-frequency oscillation incurred a wide-area outage and the economic, social loss from this phenomenon was estimated at 3 billion dollars. In order to damp out these oscillations, the PSS (Power System Stabilizer) is typically used. This, however, cannot damp out inter-area oscillations. Although research on damping inter-area oscillations is conducted to resolve the mentioned problems, the Lead Lag Controller for damping the oscillations used in FACTS (Flexible AC Transmission System) devices including VSC (Voltage Source Converter) has limitations in that it is a linear controller designed at a particular power system operating condition and there are some limitations incurred by the variable and unpredictable power system states, so that fixed controller parameters cannot properly damp out these oscillations. Meanwhile, the AI (Artificial Intelligence) techniques including supervised learning, unsupervised learning, and reinforcement learning are applied in various engineering fields in order to overcome a lot of nonlinear problems like those of power systems. In this paper, the ANN (Artificial Neural Network) controller, a kind of AI controller, was used to damp out inter-area oscillation at different power system operating conditions, after which the results were analyzed.

A major decisive task in power system stability enhancement is optimal setting of damping controller parameters. This work proposes small signal stability enhancement of power system using UPFC-based optimal PI-lead-lag controller, whose parameters are optimized by modified Grey Wolf Optimizer technique. Lead-lag structure has been very much popular in UPFC damping controller design but in this work the efficacy of lead-lag controller has been improved by proportional–integral (PI) structure. The modified GWO technique proposed here has been compared with GWO-optimized lead-lag controller and PSO, DE-optimized PI-lead-lag controller to justify its supremacy. ITAE criterion is selected for minimization problem considering an increase in input mechanical power to generator. The system eigenvalues, speed and line power deviations subjected to disturbance in power system show that the proposed PI-lead-lag controller performs better than conventional lead-lag controller and is much better in comparison to other optimization techniques to tune the controller parameters for enhancing stability of power system.

To damp the LCL -filter resonance in a grid-connected inverter, the feedback of capacitor current is usually adopted, and it can be replaced by the feedback of capacitor voltage as a low-cost solution, if an accurate digital differentiator can be made. The best way for realizing such a differentiator has so far proved to be an indirect nonideal generalized integrator (GI). As a simple alternative, this paper proposes two digital differentiators, which are directly developed in the discrete domain. They are a first-order differentiator based on backward Euler plus digital lead compensator and a second-order differentiator based on Tustin plus digital notch filter. The basic idea of the proposed methods is to correct their frequency responses to match the ideal differentiator with embedded digital filters. It is shown that the proposed differentiators exhibit the same derivative performance as the nonideal-GI differentiator, and they are more attractive for digital implementations due to their direct discrete natures, compact expressions, and easy algebraic manipulations. In particular, the proposed first-order differentiator is most competitive for its general representation and simplest implementation. Finally, a 12-kW prototype is built, and experiments are performed to verify the theoretical analysis.

The emergence of quasi Z source inverter (qZSI) in 2008 has grabbed researchers’ attention to explore new enhancement control schemes and modulation techniques in the past decade. This paper proposed a single-phase qZSI with lead compensator in the control system driven by unipolar carrier based pulse width modulation (CB-PWM) technique. Specifically, the lead compensator acts as qZSI’s outer voltage loop controller while the current inner control loop is attained via the conventional proportional (P) controller. When compared with traditional dual loop based proportional integral (PI)-P controller, the proposed controller demonstrates its superiority for the qZSI to achieve good dynamic, steady-state, and transient performances under both the continuous conduction mode (CCM) and discontinuous conduction mode (DCM) operations. All design procedures are presented thoroughly in this paper and the effectiveness and theoretical analysis of the proposed approach are verified through simulation using MATLAB/Simulink software.

In this chapter, we continue with the control of a permanent magnet (PM) brushed DC motor, but now the position control problem is considered.

Structural couplings between the flexible main rotor and the flexible drivetrain of the Bo105 helicopter are investigated by numerical simulation. For this purpose, the rotor hub constraint $$\varOmega ={\text {const.}}$$ is dropped and a drivetrain model, consisting of discrete inertia elements and intermediate flexible elements, is connected to the hub. By use of the multibody-software SIMPACK, the coupled rotor–drivetrain system is linearized and the eigenmodes are compared to those obtained with a constrained rotor hub. The drivetrain has a significant influence on the shapes and eigenfrequencies of the collective lead–lag modes. While the first collective lead–lag eigenfrequency is raised by the finite drivetrain inertia, the second is lowered due to drivetrain flexibility. To assess the influence of modeling inaccuracies on the observed couplings, the study is complemented by a sensitivity analysis. Rotor blade mass axis offset, blade pitch (causing elastic coupling) and blade precone angle have only weak influence on the coupled modes. In contrast, variations of drivetrain inertia and stiffness strongly affect the eigenfrequencies of the coupled rotor–drivetrain modes.

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.

High Voltage DC (HVDC) is now becoming a promising technology to deliver large amount of power to farthest areas of power network. Moreover, its application includes stability of surrounding grids when installed in conventional AC transmission grid. In this research, a Type-II Adaptive NeuroFuzzy Wavelet (ANFW) based damping control for HVDC has been introduced to improve the stability of overall system. This type of control enables better management of a complex system with uncertainties. This structure provides a dynamic membership function with more degree of freedom and makes it possible to grasp antecedent part uncertainties in a better way. Performance and efficiency of Type-II ANFWC is tested using chronological faults on Single Machine Infinite Bus (SMIB) system. Performance improvement of proposed controller is then investigated by comparison with conventional controls i.e. Artificial NeuroFuzzy Takagi Sugeno Kang Control (ANFTSKC) and Lead Lag Control (LLC).

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 introduces a new design method of fractional-order robust lag/lead compensators. The proposed compensators are realizable and exhibit a frequency response of fractional-order dynamics. The structure of such controllers allows one to alternate between lag/lead forms by simply interchanging two parameters with each other. An analytical design method of these controllers is simplified to reduce the number of design parameters to two}; the gain and one corner frequency of the compensator. It also ensures a robust flat phase response at their geometric mean, especially for those controllers of fractional-orders between $0.5 \lt \alpha\lt 1$. The proposed design method is straightforward and demonstrate a competitive performance to other existing ones as verified via set of numerical examples.

Električne letve volana korištene su u automobilskoj industriji. Namjena takvih sustava je smanjiti napon vozača pri okretanju volana s istim odzivom. Električne letve volana mijenjaju hidrauličke. Jedna od prednosti električne letve volana je lako podešavanje. Ovaj rad pokazuje metode projektiranja regulatora za takav sustav. Dan je matematički model. Nelinearna funkcija asistiranog okretnog momenta je definirana. Ona određuje moment generiran električnim motorom. Ulaz funkcije je izmjereni moment između volana i stupa volana izmjerenim pomoću senzora. Nelinearnost funkcije i visoko pojačanje za niske brzine kretanja vozila čini sustav nestabilnim. Dodatni kompenzacijski članovi su dodani unutar regulatora kako bi eliminirali neželjene oscilacije. Regulator je simuliran u MATLAB/Simulinku. Electric power steering system is used in the automotive industry. The purpose of such a system is to reduce driver’s effort to turn the steering wheel with the same response. Electric power systems are replacing hydraulic power systems. One advantage of electric is easy tuning. This thesis shows methods of designing a controller for such systems. A mathematical model of the system is introduced. A nonlinear assist torque map is defined which determines the torque generated by the electrical drive. The input of the torque map is torque measured between the steering wheel and the steering column via a torque sensor. The nonlinearity of this map and a high gain at low speeds makes this system unstable. Additional compensators are added to the controller to eliminate unwanted oscillations. The controller is simulated in MATLAB/Simulink.

The highly dynamic, nonlinear and complex nature of power system may cause sustained Low Frequency Oscillations (LFOs) leading toward loss of synchronization of generating units. Current source based HVDC converters could be opted to damp LFOs effectively if output current signal is modulated through an auxiliary damping controller. In this paper, a direct adaptive model free Neuro-Fuzzy Sliding Mode Control (NFSMC) is used as a supplementary damping control to modulate the current signal for current source converter based HVDC link. The intelligent NFSMC lends the learning capability from hybrid neuro-fuzzy systems and dynamic mapping ability from the hyper surface of sliding mode control (SMC). The controller parameters are updated by using simple and fast Gradient descent back propagation. The control performance is verified on a modified Single Machine Infinite Bus (SMIB) system equipped with an HVDC line connecting single machine with the utility grid. Simulation results of NFSMC are compared with conventional controls such as Lead Lag Control (LLC) and Neuro-Fuzzy Takagi-Sugeno Control (NFTSKC). The oscillation suppression performance is assessed by computing settling time and Percentage Performance Indices (PPIs), which certify the better performance of the proposed controller. MATLAB-Simulink tool was used to perform nonlinear time domain simulations.

We employ the thermal optimal path method to explore both the long-term and short-term interaction patterns between the onshore CNY and offshore CNH exchange rates (2012-2015). For the daily data, the CNY and CNH exchange rates show a weak alternate lead-lag structure in most of the time periods. When CNY and CNH display a large disparity, the lead-lag relationship is uncertain and depends on the prevailing market factors. The minute-scale interaction pattern between the CNY and CNH exchange rates change over time according to different market situations. We find that US dollar appreciation is associated with a lead-lag relationship running from offshore to onshore, while a (contrarian) Renminbi appreciation is associated with a lead-lag relationship running from onshore to offshore. These results are robust with respect to different sub-sample analyses and variations of the key smoothing parameter of the TOP method.

The Power Oscillation Damping (POD) function is for damping out oscillations. As many photovoltaic (PV) plants are installed, the POD function can be applied to a PV plant converter. In this study, the POD function was implemented on a PV plant. The stabilizing signals from the POD function were connected directly to an active power controller to damp out low frequency oscillations. A lead-lag compensator is the main structure for the POD function which adjusts the phase of the system frequency. The result of the simulation shows that the proposed POD function gives better results than the former POD functions, which send stabilizing signals through the voltage controller. There is direct adjustment of active power, and this does not affect system voltage which is an advantage of the proposed POD function.

A novel Proportional-Integral-Derivative (PID) controller is proposed for stable and unstable first order processes with time delay. The controller is cascaded in series with a second order filter. Polynomial approach is employed to derive the controller and filter parameters. Simple tuning rules are derived by analysing the maximum sensitivity of the control loop. Formulae are provided for initial guess of tuning parameter. The range of tuning parameter around the initial guess and the corresponding range of maximum sensitivity is specified based on time delay to time constant ratio. Promising results are obtained with the proposed method is compared against recently proposed methods in the literature. The comparison is made in terms of various performance indices for servo and regulatory responses separately. The proposed method is implemented for an isothermal chemical reactor at an unstable equilibrium point.

The process of selecting a step motor to an industrial application is not straightforward. Several aspects need to be considered at the beginning of the design, specially when dealing with a step motor due to its peculiar Speed × T orque relation. This paper presents a case study of a step motor selection for a food industryproblem, introducing the main aspects to be taken into account and the challenges this type of motor poses to meet the requirements. The intention is to describe the selection and design process and compare two different control approaches, first a classical approach using a lead/lag compensator, then a robust control approach using a H∞ control.

To our knowledge, this paper is the first study on the effect of information arrival on the lead–lag relationship amongst related spot instruments. Based on a large data-set of ultra-high-frequency transaction prices time-stamped to the millisecond of the S&P500 index and its two most liquid tracking ETFs, we find that their lead–lag relationship is affected by the rate of information arrival whose proxy is the unexpected trading volume of these instruments. Specifically, when information arrives, the leadership of the leading instrument may strengthen or weaken depending on whether the leading or lagging instrument responds to that information. An increase in the unexpected volume of the leader strengthens its leadership whereas an increase in the unexpected volume of the lagger weakens this leadership. In addition to the strength of leadership, an increase in the unexpected volume in response to information arrival may also have opposite effects on the lead–lag correlation coefficient depending on whether that volume increase belongs to the leader or the lagger. Finally, we find that sophisticated investors have a more significant effect on the lead–lag relationship than non-sophisticated ones.

Type 1 diabetes mellitus is one of the most common childhood diseases which, if not carefully mitigated, can pose menacing risks like hyperglycemia and ketoacidosis, ultimately leading to heart disease, kidney failure and other life-threatening complications. In order to reduce these risks, two existing control schemes are implemented with the purpose of simulation-based comparative analysis between linear and nonlinear control strategies. In this regards, H1 is selected as a nonlinear strategy whereas lead-lag compensation is the choice from the class of classical linear strategies. The designed control scheme consists of three main components: a controller, an Insulin Feedback Loop (IFL) and a Safety Mechanism (SM). IFL is designed such that it modifies the loop gain for the reduction of postprandial hypoglycemia risks, and the SM predicts the future glucose levels and acts accordingly by modifying the controller output to reduce the risk of hypoglycemia and hyperglycemia. The comparison of the transient and dynamic performances in terms of rise time, settling time and overshoot of both controllers is analysed. It is observed that the H1 gives a far sturdy response as compared to the lead-lag controller.

This paper complements the recent literature providing a thorough research of the lead lag relationship between stock and sovereign CDS markets using a rolling VAR framework. We find that the transmission channel between the credit and stock market exist. This phenomenon is time varying, it seems to be related with the economic cycle and in general, it’s more intense in US than in Europe.

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).

R IGID–FLEXIBLE coupling structures have been widely used in spacecraft with flexible attachments, robotic manipulators, and other flexible mechanical/structural systems [1–3]. Generally, the damping effect generated by the flexible components of these structures is used to improve the overall performance of the systems under dynamic loads by suppressing residual vibration [4]. However, a challenge arises when the precision positioning and motion control of the rigid–flexible coupling structures are attempted, where the residual vibration may occur due to the structural inertia and time delay resulting from the flexible components of structures [5,6]. The problem is further complicated by the existence of viscoelasticity in the flexible components of structures. It is well known that viscoelasticity is characterized by the combination of elastic springs and viscous fluids, which can be representedbyHooke’s elasticityandNewtonianviscosity, respectively. Currently, most of the existing works describe viscoelasticity by the Kelvin–Voigt damping model, which compromises between complicacy and accuracy [7,8]. However, given the rapid development of advanced space materials, the Kelvin–Voigt model was found inadequate in describing composite materials, especially for space composite materials [9]. The need for a more refinedmodel has pushed the development of viscoelasticity. In fact, as early as the 1920s,Nutting [10] found that the viscous deformation of solids, which is always interpreted as the stresshistory under strain, could be best described bya fractional-order power law decay. Nutting’s work attracted little attention due to the mathematical complexity of fractional-order calculus and the associated extensive computational effort, until the pioneeringwork on the fractional-orderMaxwell fluid byCaputo in the 1960s [11], who made the fractional-order calculus applicable for real engineering problems. Since then, it has been proved that fractionalorder calculus can describe the dynamic response of viscoelastic flexible systems more accurately than its classical integer-order counterpart due to its unique time memory capacity [7]. Nowadays, fractional-order calculus has been proved a powerful method in describing the dynamics of various materials, especially viscoelastic materials for vibration control [12]. More details of the related works can be found in [7,12,13]. However, there are no clear criteria for the selection of viscousmodels.The actualmodel used is usuallyoptimized by trial and error for different materials [14]. The control of the rigid–flexible coupling structures is addressed extensively by many control strategies and modeling schemes in literature [15–17].However, the dynamicmodels of theseworkswere generally derived by the Newtonian or Lagrangian mechanics with the Kelvin–Voigt or Rayleigh damping models. Even though the fractional-order viscous model provides an excellent alternative in describing the high stiffness and lightweight compositematerials, the fractional-order control strategy is seldom used in the control of rigid–flexible coupling structures [18–20]. In thisNote,we propose a two-parameter fractional-ordermodel of viscoelastic material. The model is then used to derive the fractionalorder dynamics of rigid–flexible coupling structures to simplify the modeling and controller design for residual vibration suppression. Based on the fractional-order dynamics, a new fractional-order lead– lag compensator design method is developed. Simulation results demonstrate the effectiveness and robustness of the fractional-order dynamics and control for the rigid–flexible coupling structures.

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 designing process of fuzzy lead-lag static synchronous series compensator (SSSC) employing whale optimization algorithm (WOA) is discussed here with the main aim to improve the stability of power system. The controller design task is taken as an optimization task and WOA is utilized to tune the controller parameters. The usefulness of the planned controller is estimated under various disturbances for single-machine infinite bus power system. To reveal the advantage of fuzzy lead-lag controller for SSSC, results are compared with differential evolution and particle swarm optimization based conventional structured SSSC controllers. The comparison of result of WOA with that of other methods exploits its superiority in the present context.

In this paper, analytical method is proposed for the design of lead compensator for specific phase margin for Qube Servo system with inertia disk as load without using graphical methods such as Polar plot, Nyquist plots, Nichols chart etc. This approach is based on V. Krishnamurthy's corollary on Routh criterion. Finally, the results have been tested on the experimental setup of Qube Servo system.