Dead Band Research Articles

Audio-frequency spectra of passive source electromagnetic fields under a cultural background: A case study from the middle and lower reaches of the Yangtze River, China

In order to study the spectra characteristics of audio-frequency passive electromagnetic (EM) fields under a cultural background, long-term audio magnetotelluric observation stations were deployed in two different typical ore districts in the middle and lower reaches of the Yangtze River (MLYR), east China, where it is widely regarded as in a typical natural and cultural mixed source environment. Data of orthogonal horizontal electric and magnetic fields were recorded continuously for months. Power spectra of the EM fields, signal coherences and apparent resistivities are estimated by employing the standard magnetotelluric robust data processing method. The observed data set is statistically analyzed by daily data and their medians for each field component. There are distinct band characteristics for the overall spectra. The spectra display very low power and are unstable in the high and low frequency “dead bands”. There are several distinguishable extreme values, including the maxima of the fundamental power-line frequency and its harmonics, the maxima of the Schumann resonances, and a minimum at 780 Hz. In the time scale, the spectra have variations both daily and annually. The spectral amplitude is greater in the nighttime than daytime only in the high frequency “dead band”, while it is greater in summer than autumn and winter in the whole observation frequency band, including the industrial power frequencies. In the spatial scale, the differences of magnetic spectrum amplitude are mainly reflected in the band of 0.35–10 Hz and the power-line frequencies between the two selected regions, which indicate the background noise level of the north is stronger than that of the south of the Yangtze River in MLYR. The results have given us a better understanding of the passive source EM fields in east China, which provide a guiding and practical value for both the natural and controlled source EM exploration methods in data collection, processing, and interpretation.

Optimal Coordinated Frequency and Voltage Control of CCGT-Thermal Plants with TIDF Controller

This paper deals with unified method of voltage and frequency control of an interconnected three unequal-area systems with the Automatic Load Frequency Control (ALFC) and Automatic Voltage Regulator (AVR) loop. Every area comprises a reheat thermal and the combined cycle gas turbine (CCGT) plant. Concerning the pragmatic system, adequate governor dead band (GDB), boiler system, and generation rate constraint (GRC) are considered in all individual plants. The Tilt-Integral-Derivative with Filter (TIDF) controller is considered in the ancillary controller of the ALFC loops, core controller of the AVR loops, and air-flow, temperature controller of the CCGT Plants. The optimized controller gains are realized through the metaheuristic algorithm called Harris Hawks Optimization algorithm along with the integral square error as a performance index considering a 1% step load perturbation in Area-1. The critical analysis shows that the performance of the TIDF controller is superlative to the classical controllers, such as PI and PID, concerning all time-domain indices. With the TIDF controller, the impacts of the AVR loop, boiler system, and the CCGT plants are analyzed on the unified ALFC and AVR study separately. Sensitivity analysis unveils the sturdiness of the TIDF controller against the change in magnitude of the step load perturbation in Area-1. Finally, the proposed unified ALFC and AVR system of three unequal-area CCGT-thermal plants is analyzed with the OPAL-RT hardware set-up for its real-time validation.

Maiden Application of Fuzzy-2DOFTID Controller in Unified Voltage-Frequency Control of Power System

This article presents an amalgamated pattern of automatic load frequency control (ALFC) and automatic voltage regulator (AVR) system in a three-area interconnected power system using the Fuzzy two-degree-of-freedom tilt-integral-derivative controller (F2DOFTID). The multi-area system includes single-stage reheat thermal plants and Solar Thermal Power Plant (STPP) in Area-1 and Heavy-Duty Gas Turbines (HDGT) in Area-2 and Area-3. An incipient attempt is made to incorporate the HDGT plant in amalgamated control of the power system. Relevant generation rate constraints (GRC) and Governor Dead Band (GDB) are rendered for thermal plants. In both ALFC and AVR systems of all areas, a first attempt is made to implement an F2DOFTID controller to alleviate the frequency and voltage deviations. In this investigation, an algorithm named Harris Hawks Optimization (HHO) is efficaciously used to accomplish optimal controller parameters. Concerning all time-domain behaviors, F2DOFTID controller performance is superior relative to the TID and 2DOFTID controller. The AVR effect proclaims a substantial improvement in system dynamics. In this amalgamated scenario, the aftermath of the high voltage direct current (HVDC) tie-line and the usage of energy storage devices such as ultra-capacitors (UC) are found superlative in the amelioration of system performance. Similarly, by modifying the generator parameters and synchronizing coefficients, the robustness of the proposed controller is measured, which signifies that obtained controller parameters during nominal conditions are resilient enough and not to be altered. Eventually, the system is also studied in OPAL-RT OP 4510 RT Lab hardware set-up for real-time analysis.

Developing a camera-based measuring system to feedback control the fibre orientation for the braiding process of CFRP

Quality control systems are inevitable in the production of safety-relevant, textile composites. In the industry, predominantly optical measuring procedures, so-called Machine Vision Systems (MVS), became generally accepted. A critical quality feature of textile structures is the carrying capacity of loads, which requires an orientation of the fibre in the direction of the load. To control the braiding angle, which determines the orientation of the fibre in braids, a feedback control system can be used. The deviation from the target angle is directly correlated to the time span between the formation and the measurement of the braiding angle, the so-called dead band. Therefore, the objective is to reduce the dead band by measuring the braiding angle with a MVS near the braiding point. This work describes and evaluates an approach to minimize the dead band by utilising a mathematical description of the braiding process to determine the origin of the braiding angle while tackling the difficulty of the convergence zone in the braiding process.

OPTIMAL DESIGN OF FRACTION-ORDER PROPORTIONAL-DERIVATIVE PROPORTIONAL-INTEGRAL CONTROLLER FOR LFC OF THERMAL-THERMAL-WIND TURBINES CONSIDERING NONLINEARITIES

The power system must be kept safe during load disturbances in order to control frequency instability during load disturbances change. Cascade Controller (CC) is employed to boost the performance of the power system mainly in the presence of nonlinear aspects. As a result, in this study, A proposed cascade fractional order proportional-derivative proportional integral (FOPDPI) controller is used to fine-tune the load frequency control (LFC) subjects of a three-area power system (thermal-thermal-wind) in the interconnected power system (IPS). As a third area in the studied model, renewable energy is used, such as high penetrating power wind turbines. The FOPDPI controller gains are adjusted using a recently published optimization scheme, such as the Harris hawk optimizer (HHO). To thoroughly test the efficiency and fitness of the proposed controller, the HHO-based FOPDPI and conventional PID controllers are applied to a three-area model with/without nonlinearities such as generation rate constraint (GRC), governor dead band (GDB), and boiler dynamics (BD) under different step load perturbation (SLP). The HHO algorithm's cost function is the Integral time multiply absolute error (ITAE) criterion. The investigation reveals that the proposed scheme HHO: FOPDPI provides greater stability than HHO: PID in both linearities by 58% and nonlinearity aspects by 62%.

Fractional Order PID Controller for Minimizing Frequency Deviation in a Single and Multi-area Power System with GRC, GDB and Time Delay

In this paper, a Fractional Order PID (FOPID) controller to minimize frequency deviation in a single and two area power system is presented. Minimizing high frequency deviation in the presence of physical constraints is very paramount in load frequency control. This is because large frequency deviation can cause the transmission line to be overloaded which may damage equipment’s at the distribution level and the mechanical devices at the generating stations. In this paper, power system with physical constraints such as Communication Delay, Governor Dead Band (GDB) and Generation Rate Constraint (GRC) were considered and modeled appropriately. An anti-windup scheme was employed to limit the effects of these physical constraints on the power system. The proposed Fractional Order PID controller was designed using the Fractional Order Modeling and Control (FOMCON) toolbox available in MATLAB/Simulink. Antlion Optimization algorithm was used to optimize the gains of the FOPID controller by minimizing Integral Square Error (ISE) as the objective function. The Integral Square Error to be minimized is the summation of the errors in frequency deviation, tie-line power deviation and the area control error. Simulation results using the proposed approach were compared with other designed methods available in literatures. Simulations were first conducted on power system designed without physical constraints, and results obtained outperformed other designed methods available in literatures for one and two area power system. Three physical constraints were then added to the proposed method, and results obtained were compared with other designed method available in literatures for power system without physical constraints. The proposed method outperformed other designed method in minimizing frequency deviation, tie-line power deviation and area control errors. However, the proposed FOPID controller took a longer time to balance the generated power and load demand when compared to other designed method for power system without physical constraints

Central Tunicate Swarm NFOPID-Based Load Frequency Control of the Egyptian Power System Considering New Uncontrolled Wind and Photovoltaic Farms

This paper presents load frequency control of the 2021 Egyptian power system, which consists of multi-source electrical power generation, namely, a gas and steam combined cycle, and hydro, wind and photovoltaic power stations. The simulation model includes five generating units considering physical constraints such as generation rate constraints (GRC) and the speed governor dead band. It is assumed that a centralized controller is located at the national control center to regulate the frequency of the grid. Four controllers are applied in this research: PID, fractional-order PID (FOPID), non-linear PID (NPID) and non-linear fractional-order PID (NFOPID), to control the system frequency. The design of each controller is conducted based on the novel tunicate swarm algorithm at each operating condition. The novel method is compared to other widely used optimization techniques. The results show that the tunicate swarm NFOPID controller leads the Egyptian power system to a better performance than the other control schemes. This research also presents a comparison between four methods to self-tune the NFOPID controller at each operating condition.

Small-signal stability analysis and frequency regulation strategy for photovoltaic sources in interconnected power system

This paper investigates the impact of high photovoltaic penetration on small signal stability of multi-source power system and proposes a new method which enables conventional PV system to improve the frequency response of the low inertia power system. The operating point of PV is linearized and shifted with respect to the change in grid frequency using a fuzzy interface system. A linearized multi-area model interconnected with tie-line comprises different generating sources is considered as a study case system. The system is extended to a more realistic network by incorporating the various system nonlinearities like generation rate constraint, governor dead band and area control error signal delay. To identify the effect of PV on system damping, eigenvalue analysis is carried out on the studies system. The proposed control scheme is found to be providing stabilizing power which may improve the frequency nadir and rate of change of frequency when the system is subjected to load change.

Robust Load Frequency Control Using Fractional-order TID-PD Approach Via Salp Swarm Algorithm

To preserve frequency and tie-line power flow within a tolerable range in modern intricate and renewable energy sources (RES) integrated power system, an intelligent, expert, and robust load frequency control (LFC) scheme is requisite. This paper proposes a new load frequency control (LFC) approach using a dual-stage controller composed of fractional-order tilted-integral-derivative (TID) and integer-order proportional-derivative (PD) controllers. The recently developed salp swarm algorithm has tuned the parameters of the controller. The proposed scheme exhibits robustness and fast disturbance rejection performance because the tilted-integral-derivative controller is structured in a fractional-order framework, and transient response is improved due to the proportional-derivative controller. The overall activity of the LFC has been further upgraded by incorporating the flexible AC transmission system (FACTS) device namely thyristor-controlled phase shifter (TCPS) unit and energy storage system called redox flow battery (RFB) units. The proposed control approach is applied to diverse types of multi-area multi-source power systems with thermal, hydro, and wind turbine units along with nonlinear functions namely generation rate constraint (GRC), governor dead band (GDB), and communication delay (CD). The simulation results yield improved frequency regulation activity with and without TCPS and RFB using the proposed control approach when compared with the recently developed LFC approaches. Sensitivity analysis also established the robustness of the proposed control approach.

A novel Quasi Opposition based controller design for hybrid AGC considering renewable energy and excitation cross coupling effect

ABSTRACT The paper addresses the Automatic Generation Control (AGC) of the interconnected two-area power system under deregulated environment. Area 1 includes thermal system, Distributed Generation (DG), and aggregate Electric Vehicle (EV) wheras area 2 contains thermal system, gas system, and aggregate electric vehicle. Nonlinearities such as Generation Rate Constraint (GRC), Governor Dead Band (GDB), Boiler Dynamics (BD), and Communication Delay (CD) are explored in the proposed test system to achieve a realistic approach. For considering cross coupling effect between excitation system and AGC, an exact model has been investigated. A novel cascade controller has been proposed to achieve the desired goal. For optimum values of controller, new novel Quasi Opposition Lion Optimization Algorithm (QOLOA) has been suggested and implemented for the studied system. The sensitivity analysis study was performed to assess the robustness of the proposed controller by varying system parameters. System parameters are varied by ±25%, ±35%, and ±50%, and the result shows the robustness of the controller and algorithm For the proposed controller, Figure of Demerit (FOD) is compared with various algorithms, and the Integral square Error (ISE) is taken as objective function. The optimistic results shows the effectiveness & superiority of proposed AGC in different scenario of deregulation.

Load Frequency Control for Power System using Generalized Extended State Observer

This study investigates load frequency control based generalized extended state observer (GESO) for interconnected power systems subject to multi-kind of the power plant. First, the mathematical model of the interconnected power system is proposed based on the dynamic model of thermal power plant with reheat turbine and hydropower plant. Second, the GESO is designed to estimate the system states and disturbances. In addition, the problem of unmeasurable system states in the interconnected power network due to lack of sensor has been solved by using the proposed load frequency control based GESO. The numerical experiments are carried out by using MATLAB/ SIMULINK simulation. The simulation results point out that the proposed control approach has the capacity to handle the uncertainties and disturbances in the interconnected power system with better transient performances in comparison with the existing control approach. The relevant dynamic models have already been used for the simulation of the physical constraints of the governor dead band (GDB) and generation rate constraint (GRC) effect in the power plants. It is evident that the robustness of the suggested controller in terms of stability and effectiveness of the system. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

Designing an electricity distribution reward-penalty scheme based on spatial reliability statistics

The Reward-Penalty Scheme (RPS), a financial strategy developed by the regulator to avoid service reliability deterioration, is often used to guarantee the reliability level. This paper provides the new methodology for RPS design based on the spatial distribution of reliability performances. The analytical form of the spatial performance distribution is obtained using a method of moments. Using this distribution, the Dead Band Zone and reward and penalty points for each utility are obtained. This analysis offers a more transparent set of reward and penalty thresholds. The proposed methodology is tested on actual data from a Serbian distribution utility.

Utilization of electric vehicles in combined voltage‐frequency control of multi‐area thermal‐combined cycle gas turbine system using two degree of freedom tilt‐integral‐derivative controller

AbstractThis paper conveys the unified control pattern of frequency and voltage of interconnected multi‐area power system through the automatic load frequency control (ALFC) loop and automatic voltage regulator (AVR) loop. Each area includes a single‐stage reheat thermal plant, combined cycle gas turbine (CCGT) plant, and electric vehicles (EVs). Pertinent generation rate constraint for thermal and CCGT plant and governor dead band for the thermal plant is considered. A maiden attempt has been made to introduce the two degree of freedom tilt‐integral‐derivative (2DOFTID) controller for both the ALFC and AVR loops. In this study, a meta‐heuristic algorithm called Harris Hawks optimization (HHO) is implemented to optimize the controller parameters. Study divulges that performance of the 2DOFTID controller predominates when compared with TID and proportional‐integral‐derivative with filter (PIDF) controller apropos time‐domain indices. By juxtaposition, the superiority of the proposed algorithm and performance index is observed. Also, improved system dynamics were independently exhibited by the influence of the lumped EV model and AVR. For the predominance of the 2DOFTID controller, different patterns of disturbances such as random and sinusoidal varying load perturbation have been investigated. Eventually, the sensitivity studies were accomplished to determine the sturdiness of the proposed controller for substantial variations in the system parameters.

Multi-layer Laser Mirrors for Optical Sensors Deposited by Electron Beam Deposition and Ion Assisted Electron Beam Deposition

High reflectivity and low loss mirrors are very much essential for state-of art sensors like Ring Laser Gyroscopes widely used for navigation of moving platforms. Surface scattering is the main source of loss for the Laser mirrors of high reflectivity. Surface scattering also lead to coupling of back reflected light leading to dead band of optical sensors at low input rotation. Super polished glass substrates have been prepared from low expansion glass ceramic material. Surface roughness is achieved about 3-5Å (RMS value) for the ceramic glass substrates prior to thin film coating. The substrates are deposited with 41 alternative layers of SiO2 and Ta2O5 of Quarter-Wave optical thickness with Electron Beam Deposition (EBD) technique. Ion beam Assisted Electron Beam Deposition (IAEBD) is used for another batch of substrates to coat identical stack of layers on glass substrates of the same surface quality. The key process parameters of both the coating processes are presented. The optical constants of the films are evaluated with spectroscopic Ellipsometer from 400nm to 1600nm. Total Integrated Scattering is estimated from the achieved surface finishing of mirrors deposited. The multi-layer coatings are characterized with UV-Vis-IR Spectrophotometer and Cavity Ring Down(CRD) loss meter. The quantitative optical loss of the mirrors is measured at 45o angle of incidence with CRD loss meter. The merits of ion assisted EB process over simple EB coating processes are evaluated against optical constants of thin films and performances of mirrors. Fitness of the processes for realizing Laser mirrors for optical sensors at 632.8nm is evaluated.

Impact of Inertia Emulation Based Modified HVDC Tie-Line for AGC Using Novel Cascaded Fractional Order Controller in Deregulated Hybrid Power System

This article deals with the Automatic Generation Control (AGC) mechanism for an interconnected, deregulated hybrid power system. The physical generation constraints such as boiler dynamics, governor dead band (GDB) and generation rate constraints (GRC) are included for a more realistic approach. The integration of distributed generation (DG) systems is also considered to match with present scenario. The intermittency nature of the DGs ruins the system's inertia and dynamic behaviour. A novel cascaded fractional order controller configuration 2-DOF (FOPIλDN)-PDN is proposed for the AGC mechanism and a new quasi opposition based volleyball premier league (QVPL) algorithm is employed to optimize the controller gains. On the other hand, the inertia emulation strategy (IES) based modified HVDC tie-line is used parallel to the AC tie-line to retrace the power system's inertia. The impact of the proposed controller and IES based modified HVDC tie-line has been analysed by subjecting to several case studies. The effectiveness of the QVPL based proposed controller has also been tested by comparing it with the previously published works on the same platform.

Processing of passive EM fields acquired during active-source airborne EM surveys

The recording of raw or streamed airborne electromagnetic (AEM) data, as done by CGG during MEGATEM surveys, allows for the extraction of passive EM signals also present, but not normally processed. These include (1) powerline responses, (2) responses in the very low frequency (VLF) range due to radio transmissions and (3) natural-source audio-frequency magnetic (AFMAG) and VLF responses in the frequency range 25 Hz–25 kHz extracted from individual atmospheric electrical discharges (sferics). The latter approach manages to extract good signal in the audio-frequency magnetotelluric (AMT) dead band (1–5 kHz) for one of the discussed data sets. The recording of the three-component AEM data allows for the vector processing of these passive EM responses, including the derivation and modelling of the vertical-to-horizontal magnetic field ratio (tipper) data. Conductivity information can be derived from the tipper data with an apparent conductivity transformation and, more rigorously, with 2D and 3D inversions that take into account the terrain’s topography. The extraction and modelling of passive EM responses is demonstrated on two data sets. A powerline apparent-conductivity grid derived from a MEGATEM survey near Timmins, Canada indicates conductivity structures similar to those in the corresponding active-source EM data. VLF and AFMAG responses derived from South American MEGATEM data show a strong correlation to topography. These data were successfully modelled with 2D and 3D inversions, and the derived shallow conductivity structures confirm and complement the information extracted from the active-source EM data.

Magnetotelluric multi-reference array data processing algorithm

Rational use of multiple remote reference data is an important way to improve the data quality of MT method. Based on the electromagnetic array data processing model, a data processing algorithm with multiple reference stations is proposed. Firstly, reference channels are selected from multiple remote stations to construct the natural field dominated reference data array; then the polarization parameters of natural sources are extracted from the reference data array by robust principal component analysis method; the parameters are then applied to the target array, which constructed by data from the stations to be processed, to estimate the target tensor impedances by robust estimation method. Finally, the effectiveness of the proposed algorithm is discussed by comparing it with the robust least squares and conventional remote reference methods, using a case study in east China. The results show that the new scheme is an effective strategy by using the multiple reference channel data, which can improve the quality of MT data processing in noisy environment and provide a reasonable correction for MT “dead band” distortions.

Enhancement of frequency regulation in tidal turbine power plant using virtual inertia from capacitive energy storage system

Frequency stability has been a significant issue for a long time for the proper operation of isolated microgrids. Most distributed energy sources have converter-based interface and do not normally respond to frequency deviations. By increasing the penetration of the renewable sources like tidal power, solar power, wind power etc. into the microgrid provides power support but at the expense of a diminishing in inertia and initial frequency regulation. Owing to this, both the maximum frequency nadir and the rate of change of frequency deviation worsen, which creates a risk to frequency regulation. In this investigation, the support of the deloaded tidal power plants with various degree of infiltration in frequency regulation utilising controlling methods such as inertia control and droop control are evaluated. This investigation proposes an integral tilt derivative droop controller in deloaded area to suppress frequency deviation (ΔF) over fixed and proportional integral derivative (PID) droop controllers. Outcomes of these controllers have been evaluated in MATLAB Simulink. Supplementary support of virtual inertia from capacitive energy storage system is also investigated on frequency regulation. Moreover, the effect of consolidated outcomes of inertia and droop controlling methodologies with capacitive energy storage systems on frequency response is likewise discussed. To demonstrate the robustness of the proposed model nonlinearity factors like generation rate constraint and governor dead band are added.

수용용량과 계통 손실을 고려한 스마트 인버터의 최적 Volt-VAR 제어 곡선 선정에 관한 연구

The penetration of Renewable Energy Source (RES) has been increasing because RES is drawing attention by the environmental problem in the worldwide. The power flow can be changed from unidirectional to bidirectional because of increasing the penetration of RES. In bidirectional system, the efficient operation of conventional Voltage Regulators (VRs) is difficult. As one of the various methods to reinforce the conventional VR, the Volt-VAR control of the Smart Inverter (SI) is used for supporting the voltage by using the reactive power of RES. In this paper, the Volt-VAR control curve with the modified dead band is analyzed for the factors affecting the Hosting Capacity (HC) and the enhanced method to obtain the maximum HC. The modified Volt-VAR control curve is applied and the power flow is calculated through Open source Distribution System Simulator (OpenDSS). The maximum HC is obtained through Genetic Algorithm (GA) using MATLAB.

FACTS-based 3DOF-PID Controller for LFC of Renewable Power System Under Deregulation Using GOA

ABSTRACT This article introduces grasshopper optimization algorithm (GOA) for getting an optimum and effective solution of an automatic generation control (AGC) problem in hybrid power systems under a deregulated scenario using a 3-degree freedom of proportional integral and derivative (3DOF-PID) controller. Initially, two-area thermal-hydro-gas-wind system is considered. To compensate the load disturbances and to stabilize the area frequency oscillations, dynamic power flow control with PID and 3DOF-PID controllers have been studied. The performances of PID and 3DOF-PID controllers are evaluated with high voltage direct current (HVDC) link. The present investigation reveals that GOA-optimized 3DOF-PID controller is better than any other conventional technique, such as moth swarm algorithm (MSA) optimization technique. Afterward, a two-area AGC system is considered, where in one area wind power plant is incorporated with a thermal hydro plant and in the other area solar thermal power-plant (STPP) is incorporated with the same combination. Additionally, the effectiveness of different flexible AC transmission system (FACTS) devices e.g. unified power flow controller (UPFC) and super conducting magnetic energy storage device (SMES) along with 3DOF-PID controller-based AGC is compared with PID controller-based AGC. Moreover, to make the AGC problem more realistic, initially generation rate constraints (GRC) and governor with dead band (GDB) and finally boiler dynamics (BD) are included in thermal unit, and performance of the proposed controller using proposed algorithm is evaluated under deregulated environment. Finally, the proposed technique is applied under random load variation.