Dead Band Research Articles

Quasi-oppositional differential search algorithm applied to load frequency control

In this article, quasi-oppositional differential search algorithm (QODSA) is proposed for finding an optimal and effective solution for load frequency control (LFC) problem in the power system. Initially, original DSA is employed for fine-tuning of the secondary controller of LFC system and then, quasi-oppositional based learning (Q-OBL) mechanism is integrated into the original DSA to enhance the convergence speed and to find a better solution of LFC problem. To validate the effectiveness of proposed QODSA, four widely used interconnected power system networks are designed and analyzed. The superiority of the proposed method is established by an extensive comparative analysis with other existing evolutionary algorithm’s (EA) using transient analysis method. A critical investigation of simulation results reveals that the proposed QODSA gives simple and better solution compared to original DSA and other reported algorithms. To study the robustness of QODSA, two different random load patterns are projected and results confirm the robustness of the designed controllers. To add some degree of nonlinearity, generation rate constraint and governor dead band effects are considered and their consequence on the system dynamics has been examined. Finally, sensitivity analysis is performed with a wide variation of system parameters.

Grey Wolf Optimization to Solve Load Frequency Control of an Interconnected Power System

In this article, a novel optimization algorithm called grey wolf optimization (GWO) with the theory of quasi-oppositional based learning (Q-OBL) is proposed for the first time to solve load frequency control (LFC) problem. An equal two-area thermal power system equipped with classical PID-controller is considered for this study. The power system network is modeled with governor dead band and time delay nonlinearities to get better insight of LFC system. 1% load perturbation in area-1 is considered to appraise the dynamic behavior of concerned power system. Integral time absolute error and least average error based fitness functions are defined for fine tuning of PID-controller gains employing the proposed method. An extensive comparative analysis is performed to establish the superiority of proposed algorithm over other recently published algorithms. Finally, sensitivity analysis is performed to show the robustness of the designed controller with system uncertainties.

Optimal Control of Li-Ion Battery Energy Storage System for Frequency Regulation

The usage of renewable energy to supply electricity demands is expected to increase drastically in the coming years. This is attribute to the encouragement of the government through policies such as RPS(renewable energy portfolio standards) and FIT(feed-in-tariffs). However, the performance of power system is sometimes critically constrained by stability characteristics. It is very challenging for system operators to manage a high penetration of renewable energy resources in a bulk power system, as they are known to deteriorate the dynamic performance of power systems.Therefore, it has been proposed that the large-scale Energy Storage System (ESS) of which power output can be controlled accurately and quickly can be applied to a bulk power system for securing the stability of the system despite a high penetration of the renewable energy resources. By increasing deployment of renewable energy, importance of power grid stability has been increased. For example, Wind Power has characteristics of difficult prediction and rapid variation depending on the regional climate characteristics. Energy Storage System aims to transform an uncontrollably variable and partially unpredictable renewable energy into a controlled and predictable one. For these purpose, a quickly responsive and highly efficient control-algorithm is essential. It is for using such a high performance of ESS when a disturbance occurs on a electrical grid system.KEPCO implemented a demonstration project on large-scale grid connected 4 MW / 8 MWh Battery ESS (BESS) using Lithium-Ion Battery (LIB). Fig. 1 shows the interconnection of ESS at the demonstration site. The 4 MW / 8 MWh BESS is connected to both the 22.9kV substation bus and the distribution line in Jocheon, Jeju Island for offshore wind turbines. In this study, Operation strategies for the BESS were developed for frequency regulation of the grid-system. Fig. 1 Interconnection of ESS at Jocheon Substation For power system frequency regulation, There are two kinds of control strategies through ESS here. One is for the normal status that the ratio of frequency change is not bigger than reference ratio of frequency change(ξ). The reference ratio is frequency changes per second when the smallest power supply was failed from the power system. The other is for the dynamic status that the ratio of frequency change is bigger than the reference ratio. In case of South Korea, it is about -0.306 Hz/sec. It could be variable every year because the total amount of power supply in the grid-system would be different. In this paper, we researched briefly about the normal status.At normal control mode, the power output(P) of the ESS is proportional to the change in frequency(f). kd is a proportional coefficient set by the droop characteristics of a battery generation.P=kd(60-f) In order to distribute output power of each battery, this study established a SOC(State Of Charge) weighted control strategy that can consider the SOC of each battery. The following factors were considered to provide frequency regulation service while considering the SOC :1) Set proportional coefficient (kd) for calculating total output demand2) Set priority at output distribution according to SOC3) Consider rating output of each battery when distributing outputAt normal status, the proportional coefficient(kd) was set by applying the droop of a general generator. This is to control the ESS output with a performance similar to the droop of the general generator. When allocating output demand determined by each battery SOC through this strategy, the battery with a higher SOC have priority in distribution. This is more efficient way to fulfill the total output demand cost-effectively. The SOC weighted control result is shown in Figure 2.Fig. 2 Result of battery output during SOC weighted control (simulation)It can be found that the distributed quantity of output was provided depending on the SOC level of each battery. It's likely to be seen that a battery with a higher SOC has priority in the distribution of output.SOC management effect of the control algorithm was analyzed through a 5-hour too. The result obtained from a simulation frequency of five hours before and after a credible accident. We can find that, in the range within dead band, the control of battery was conducted in order to reach a SOC sustainment section. When the frequency is in the dead band, ESS is not working for frequency regulation. In the outside range of the frequency dead band, it was observed that control capacity was distributed according to SOC in order to provide frequency regulation.

Automatic Generation Control of Two Equal Areas with Traditional Controllers

Automatic generation control (AGC) is major issue in power system whose main purpose is to maintain the frequency and tie line power flow during normal period in an interconnected system. . Thus, It is the responsibility of the Power system engineers to ensure that adequate power is delivered to the load reliably and economically so that nominal condition will be re-established The main focus is to maintain the value of frequency in its prescribed limit. We use renewable source which are important as well as non renewable sources at the level of extinct. As renewable alone cannot reliable then we use interconnection of both for making the system reliable and more efficient.This research paper is devoted to explore the interconnection of the automatic generation control of hydro power system and wind system. The wind system is comprised with governor dead band, generation rate constraint and turbine dynamics where as the hydro system is comprised with generation rate constraint. The traditional PI controller does not have adequate control performance with the consideration of nonlinearities and turbine dynamics. To overcome this drawback, PID controllers helps in solving optimization problems by exploitation of random search. It will provide the system security also for maintain the frequency in prescribed limit with the help of simulation.

Impact of demand response for frequency regulation in two-area thermal power system

Summary In future power system operation, wide area monitoring applications will rely heavily on demand response (DR) because of its inherent characteristics mainly in ancillary services (AS). The DR is widely applied in power system; however, impact of DR loop with communication delay on dynamic performance of two-area power system, mainly load frequency control (LFC), have not been reported by researchers. This paper presents the impact of DR control loop with communication delay in two-area thermal power systems for improvement in frequency deviation profile. The optimal power sharing between supplementary and DR loop control is presented for different load variations. Further, efficacy of controller performance is also validated by introducing non-linearities in generation in terms of generation rate constraint (GRC) and governor dead band (GDB). The simulations are performed with inclusion of DR for LFC control problem in (i) single-area, (ii) two-area thermal and (iii) thermal power system integrated with pumped hydropower system to improve the dynamic performance of system and hence minimize the frequency deviation. The controller in supplementary loop and DR loop is optimized using particle swarm optimization (PSO) technique. Copyright © 2016 John Wiley & Sons, Ltd.

AGC of dish‐Stirling solar thermal integrated thermal system with biogeography based optimised three degree of freedom PID controller

The present study emphasises the application of dish-Stirling solar thermal system (DSTS) in automatic generation control (AGC) of an unequal two area thermal system. The thermal systems are equipped with single reheat turbine, generation rate constraint, and governor dead band. The system dynamics with and without DSTS are tested for integral, proportional integral, proportional integral derivative, and three degree of freedom proportional integral derivative (3DOF-PID) as secondary controllers. The simultaneous optimisation of the controller parameters for each controller is done with biogeography based optimisation (BBO) technique. The 3DOF-PID controllers for the system having DSTS outperform the other controllers in terms of magnitude of oscillation, peak deviation, and settling time in system dynamic responses. The same is validated with random load perturbation. Sensitivity analysis proves that BBO optimised 3DOF-PID controller parameters obtained at nominal conditions are healthy enough. These optimised 3DOF-PID controller parameters are not necessarily needed to optimise for wide changes in system loading, and inertia constant H; step load perturbation (SLP) in all areas and higher SLP in area1. Integration of DSTS for AGC of thermal system is safely attributed.

Applying fractional order PID to design TCSC-based damping controller in coordination with automatic generation control of interconnected multi-source power system

In this paper, fractional order proportional-integral-differential (FOPID) controller is employed in the design of thyristor controlled series capacitor (TCSC)-based damping controller in coordination with the secondary integral controller as automatic generation control (AGC) loop. In doing so, the contribution of the TCSC in tie-line power exchange is extracted mathematically for small load disturbance. Adjustable parameters of the proposed FOPID-based TCSC damping controller and the AGC loop are optimized concurrently via an improved particle swarm optimization (IPSO) algorithm which is reinforced by chaotic parameter and crossover operator to obtain a globally optimal solution. The powerful FOMCON toolbox is used along with MATLAB for handling fractional order modeling and control. An interconnected multi-source power system is simulated regarding the physical constraints of generation rate constraint (GRC) nonlinearity and governor dead band (GDB) effect. Simulation results using FOMCON toolbox demonstrate that the proposed FOPID-based TCSC damping controller achieves the greatest dynamic performance under different load perturbation patterns in comparison with phase lead-lag and classical PID-based TCSC damping controllers, all in coordination with the integral AGC. Moreover, sensitivity analyses are performed to show the robustness of the proposed controller under various uncertainty scenarios.

Learning in parking lots: Affinity spaces as a framework for understanding knowledge construction in informal settings

Abstract Before, during, and after concerts, fans of The Grateful Dead, Phish, Widespread Panic, and other improvisation-oriented jam bands, gather in venues' parking lots to share experiences, debate band related lore, buy and sell fan made goods, listen to music, and participate in numerous other scene-related activities. The interaction within these spaces, and with these spaces, fosters the social construction of knowledge, language, skills, norms, behaviors, and identities. By applying Gee's construct of “affinity space,” this article analyzes the different trajectories to learning and participation associated with one the most influential fandoms in the United States. The conceptualization of parking lots as affinity spaces sheds lights on informal learning practices experienced in physical settings that transcend the affordances offered by virtual communities, social media, and, more broadly, computer-mediated communication. Focusing on situated learning endeavors enacted in jam band parking lots in relation to formal educational practices, this study advocates for a renewed and joined approach to education and fandom studies through a sociocultural lens.

39-2: New In-cell Capacitive Touch Panel Technology with Low Resistance Material Sensor and New Driving Method for Narrow Dead Band Display

39-2: New In-cell Capacitive Touch Panel Technology with Low Resistance Material Sensor and New Driving Method for Narrow Dead Band Display

Maiden application of hybrid pattern search‐biogeography based optimisation technique in automatic generation control of a multi‐area system incorporating interline power flow controller

This study exhibits the automatic generation control (AGC) of an unequal three-area thermal system having single reheat turbine, generation rate constraint, and governor dead band, in all areas. A three-degree-of-freedom proportional-integral-derivative (3DOF-PID) controller is used as secondary controller in all the areas and its dynamic performance is compared with that of classical PI, ID, and PID controllers. The controller parameters are simultaneously optimised using biogeography-based optimisation (BBO) technique, where 3DOF-PID controller outperforms the other. A hybrid pattern search BBO (hPS-BBO) technique is applied for the first time in AGC, to simultaneously optimise 3DOF-PID controller parameters. Comparison of dynamic responses corresponding to BBO and hPS-BBO optimised 3DOF-PID controller gives better performance of the latter. This is also validated with random disturbance. The considered system is checked for optimal location of interline power flow controller (IPFC) using BBO optimised 3DOF-PID controller. Observations reveal that IPFC placed between Line1 and Line3 is the optimal location. A comparatively better response is observed with hPS-BBO optimised 3DOF-PID controller parameters, having IPFC placed in its optimal location. Sensitivity analysis of the hPS-BBO optimised 3DOF-PID controller parameters is tested and found satisfactory for variations in system loading and inertia constant H .

Impact of Governor Deadband on Frequency Response of the U.S. Eastern Interconnection

This paper documents the effort to perform dynamic model validation for the U.S. Eastern Interconnection (EI) by modeling the governor deadband. The Western Electricity Coordinating Council-modified 1981 IEEE type 1 turbine governor model (WSIEG1) was added to the EI model. A frequency response sensitivity study is conducted to look at the impacts of a few major factors. The significance of modeling governor dead band is evident. Simulated frequency responses are adjusted and validated against the measurements collected by the frequency monitoring network. Two actual events are replicated in a 16 000-bus EI dynamic model. This paper demonstrates the need for a comprehensive effort on governor dead band modeling by the industry.

Bat inspired algorithm based optimal design of model predictive load frequency control

Bat inspired algorithm (BIA) has recently been explored to develop a novel algorithm for distributed optimization and control. In this paper, BIA-based design of model predictive controllers (MPCs) is proposed for load frequency control (LFC) to enhance the damping of oscillations in power systems. The proposed model predictive load frequency controllers are termed as MPLFCs. Two-area hydro-thermal system, equipped with MPLFCs, is considered to accomplish this study. The suggested power system model considers generation rate constraint (GRC) and governor dead band (GDB). Time delays imposed to the power system by governor-turbine, thermodynamic process, and communication channels are accounted for as well. BIA is utilized to search for optimal controller parameters by minimizing a candidate time-domain based objective function. The performance of the proposed controller has been compared to those of the conventional PI controller based on integral square error (ISE) technique and the PI controller optimized by genetic algorithms (GA), in order to demonstrate the superior efficiency of the BIA-based MPLFCs. Simulation results emphasis on the better performance of the proposed MPLFCs compared to conventional and GA-based PI controllers over a wide range of operating conditions and system parameters uncertainties.

Pressure regulation for earth pressure balance control on shield tunneling machine by using adaptive robust control

Most current studies about shield tunneling machine focus on the construction safety and tunnel structure stability during the excavation. Behaviors of the machine itself are also studied, like some tracking control of the machine. Yet, few works concern about the hydraulic components, especially the pressure and flow rate regulation components. This research focuses on pressure control strategies by using proportional pressure relief valve, which is widely applied on typical shield tunneling machines. Modeling of a commercial pressure relief valve is done. The modeling centers on the main valve, because the dynamic performance is determined by the main valve. To validate such modeling, a frequency-experiment result of the pressure relief valve, whose bandwidth is about 3 Hz, is presented as comparison. The modeling and the frequency experimental result show that it is reasonable to regard the pressure relief valve as a second-order system with two low corner frequencies. PID control, dead band compensation control and adaptive robust control (ARC) are proposed and simulation results are presented. For the ARC, implements by using first order approximation and second order approximation are presented. The simulation results show that the second order approximation implement with ARC can track 4 Hz sine signal very well, and the two ARC simulation errors are within 0.2 MPa. Finally, experiment results of dead band compensation control and adaptive robust control are given. The results show that dead band compensation had about 30° phase lag and about 20% off of the amplitude attenuation. ARC is tracking with little phase lag and almost no amplitude attenuation. In this research, ARC has been tested on a pressure relief valve. It is able to improve the valve’s dynamic performances greatly, and it is capable of the pressure control of shield machine excavation.

Hybrid evolutionary algorithm based fuzzy logic controller for automatic generation control of power systems with governor dead band non-linearity

AbstractA new intelligent Automatic Generation Control (AGC) scheme based on Evolutionary Algorithms (EAs) and Fuzzy Logic concept is developed for a multi-area power system. EAs i.e. Genetic Algorithm–Simulated Annealing (GA–SA) are used to optimize the gains of Fuzzy Logic Algorithm (FLA)-based AGC regulators for interconnected power systems. The multi-area power system model has three different types of plants i.e. reheat, non-reheat and hydro and are interconnected via Extra High Voltage Alternate Current transmission links. The dynamic model of the system is developed considering one of the most important Governor Dead Band (GDB) non-linearity. The designed AGC regulators are implemented in the wake of 1% load perturbation in one of the control areas and the dynamic response plots are obtained for various system states. The investigations carried out in the study reveal that the system dynamic performance with hybrid GA–SA-tuned Fuzzy technique (GASATF)-based AGC controller is appreciably superior as...

Participation of PMSG-based wind farms to the grid ancillary services

With the increased penetration of wind energy in many utility grids throughout the world, transmission system operators (TSO) are facing further difficulties regarding power system control and stability. Therefore, modern wind farms should participate to the primary voltage and frequency control of power systems. This paper presents the design of a supervisory control strategy for grid-connected wind farms. Wind turbines within the investigated wind farm are pitch controlled and use the Direct Drive technology. It has a total installed capacity of 50MW and it includes 25 PMSG-based wind turbines with a rated power of 2M each. The proposed supervisor is developed with all features that make the wind farm able to provide active and reactive power control. It includes automatic voltage and frequency control with droop and dead band. Performances of this supervisor are evaluated in terms of compliance with the Danish TSO requirements.

Design and analysis of multi-source multi-area deregulated power system for automatic generation control using quasi-oppositional harmony search algorithm

The present article focuses on the study of automatic generation control (AGC) of a realistic power system having a distinct combination of multi-area multi-source generating units in each control area under deregulated framework. An attempt is made in this paper to integrate reheat thermal, hydro and gas generating unit in a single control area and, then, extended this combination to five control areas. In this work, six reheat thermal, six hydro and three gas generating units are taken into account for the modeling of five-area power system. Some important physical constraints like time delay, governor dead band and generation rate constraint are imposed in the power system dynamics to get an accurate perception of the deregulated AGC subject. The highlighting features of the present work are to model, simulate, optimize and co-relate their inter-related dynamic performances for the purpose of AGC study. For such a complex AGC model, the vital role of the proposed quasi-oppositional harmony search (QOHS) algorithm, as an optimizing tool, is signified while solving the AGC problem in deregulated regime. The simplicity of the structure and acceptability of the responses of the well-known proportional–integral–derivative controller, inherently, enforces to employ in this work. The three classes of extensive deregulated cases (in the presence of load following and physical constraints) are demonstrated by examining the closed loop performance of the studied model. The simulation results show that the designed power system model may be a feasible one and the proposed QOHS algorithm may be a promising optimization technique under these circumstances.

Application of backtracking search algorithm in load frequency control of multi-area interconnected power system

Abstract This paper introduces a new powerful evolutionary algorithm called backtracking search algorithm (BSA) for solving load frequency control (LFC) problem in power system. Initially, two-area non-reheat thermal power plant is considered and gains of PI/PID controllers are optimized using BSA. This paper compares BSA’s effectiveness in solving LFC problem with the performances of other optimization techniques reported in the literature. Nonlinearities of power system such as reheater, governor dead band, boiler dynamics and generation rate constraint are included in the system modeling to identify the system stability and its performance is compared with craziness based PSO technique. Additionally, two more test systems namely three-area and four-area hydro-thermal plant with nonlinearity are considered to demonstrate the efficiency of proposed algorithm. The comparative analysis of the performances indicates that the proposed controller gives better results than other techniques available in the literature. Sensitivity analysis showed robustness of proposed controller under loading and parameter uncertainty.

Performance of optimal hierarchical type 2 fuzzy controller for load–frequency system with production rate limitation and governor dead band

Controlling load–frequency is regarded as one of the most important control-related issues in design and exploitation of power systems. Permanent frequency deviation from nominal value directly affects exploitation and reliability of power system. Too much frequency deviation may cause damage to equipment, reduction of network loads efficiency, creation of overload on communication lines and stimulation of network protection tools, and in some unfavorable circumstances, may cause the network collapse. So, it is of great importance to maintain the frequency at its nominal value.It would be useful to make use of the type 2 fuzzy in modeling of uncertainties in systems which are uncertain. In the present article, first, the simplified 4-block type-2 fuzzy has been used for modeling the fuzzy system. Then, fuzzy system regulations are reduced by 33% with the help of hierarchy fuzzy structure. The simplified type-2 fuzzy controller is optimized using the Cuckoo algorithm. Eventually, the performance of the proposed controller is compared to the Mamdani fuzzy controller in terms of the ISE, ITSE, and RMS criteria.

Application of multi-objective PID controller for load frequency control in two-area nonlinear electric power systems

Design of optimal controllers is indeed a multi-objective optimisation problem. Non-dominated sorting in genetic algorithms-II (NSGA-II) is a popular algorithm for solving multi-objective optimisation problems. This paper investigates the application of NSGA-II technique for the tuning of a proportional-integral-derivative (PID) controller for a class of identical two area-thermal power stations including the generation rate constraint (GRC) and boiler nonlinear dynamics as well as the governor dead band (GDB). The design objective is to improve the damping of frequency fluctuation in two-area power system when subjected to a disturbance in their loads. The proposed technique is applied to generate Pareto set of global optimal solutions to the given multi-objective optimisation problem. Further, the two PID controllers in each area are assumed to have identical structures (same parameters). Simulation results using the tuned multi-objectives-based GA PID controller are presented. The effectiveness of the proposed scheme is confirmed using MATLAB-Simulink software.

Performance comparison of TCSC with TCPS and SSSC controllers in AGC of realistic interconnected multi-source power system

Abstract The primary goals of employing series flexible ac transmission system (FACTS) in automatic generation control (AGC) studies of interconnected power systems are mitigating area frequency and tie-line power oscillations. This paper compares dynamic performance of thyristor controlled series capacitor (TCSC) as damping controller with thyristor controlled phase shifter (TCPS) and static synchronous series compensator (SSSC) which are series FACTS damping controllers. Commonly used lead-lag controllers are used in structure of damping controllers. The effect of TCSC in tie-line power exchange is modeled mathematically based on the Taylor series expansion for small-signal load disturbance. The performance of the proposed TCSC controller in coordination with integral AGC is compared with cases of TCPS–AGC and SSSC–AGC. An improved particle swarm optimization (IPSO) algorithm and integral of time multiplied squared error (ITSE) performance index are used to design the damping controllers. A two-area power system having generations from reheat thermal, hydro, and gas units in each area is evaluated regarding nonlinearity effects of generation rate constraint (GRC) and governor dead band (GDB). The simulations results in MATLAB/SIMULINK environment show that the proposed TCSC–AGC yields superior performance than others in damping of area frequencies and tie-line oscillations. Furthermore, sensitivity analyses are performed to show greater robustness of TCSC–AGC.