Governor Dead Band Nonlinearity Research Articles

Hybrid cyber-attack compensation of sustainable microgrid using active disturbance rejection control strategy

A modified active disturbance rejection control (ADRC) strategy for the frequency regulation of sustainable microgrid against hybrid cyber-attacks is proposed in this paper. The proposed technique mitigates the effect of attacks which in turn regulates the frequency of microgrid. The sustainable microgrid consists of solar and wind as renewable energy sources, energy storage systems (ESSs) like battery ESS and flywheel ESS, and controllable sources of energy like fuel cell and diesel generator. The cyber-attacks such as false data injection, denial-of-service and time delay attack are considered for designing the proposed ADRC technique. The robustness of the microgrid system with the proposed controller is investigated by varying generation and load, stochastic nature of attacks, parametric uncertainties and generation rate constraint and governor dead band nonlinearities. Further, the stability analysis of the microgrid with proposed ADRC is investigated under the aforementioned cyber-attacks using the small gain theorem.

An effective method based on simulated annealing for automatic generation control of power systems

In this study, a novel hybrid Simulated Annealing-Genetic Algorithm (hSA-GA) is proposed. In the hSA-GA, population-based SA is used and each solution in the population is improved using the local search operator. The information exchange between the improved solutions is provided by the crossover operator. A new selection operator is used to ensure the balance between intensification and diversification. The hSA-GA is tested first on nine benchmark functions. Then it is used for tuning proportional–integral–derivative (PID) parameters for automatic generation control (AGC) of multi-area interconnected power systems. Firstly, PID parameters are determined with hSA-GA on a two-area interconnected non-reheating thermal system (System-1) in two different generator time constants. Secondly, to demonstrate the effect of supplementary control in AGC systems, the system is simulated with hSA-GA tuned PID controller and without controller. Additionally, the performance of the proposed hSA-GA is observed on AGC system of two area thermal power system with governor dead-band (GDB) nonlinearity (System-2). Transient responses of Δf1, Δf2 and ΔPtie obtained for both System-1 and System-2 are compared with studies on the same systems in the literature and it is seen that hSA-GA exhibits better control performance on power systems than compared studies. The proposed algorithm shows the best performance in System-1 (when Tg=0.08). Accordingly, settling times of Δf1, Δf2 and ΔPtie are reduced to 2.33 s, 3.783 s and 3.11 s, respectively. Finally, the non-linear two area thermal power system is tested with a load varying between ±50% for 180 s to validation of proposed algorithm and results are compared relevant studies.

Optimal design of fuzzy-PID controller for automatic generation control of multi-source interconnected power system

This paper suggests a fuzzy logic controller (FLC) structure from seven membership functions (MFs) and its input–output relationship rules to design a secondary controller to reduce load frequency control (LFC) issues. The FLC is coupled to a proportional–integral–derivative (PID) controller as the proposed FPID controller, which is tuned by an optimized water cycle algorithm (WCA). The proposed WCA: FPID scheme was implemented with two models from the literature under the integral time absolute error cost function. Initially, a two-area non-reheat unit was implemented, and the gains of PID and FPID controllers were adjusted to verify the suitability of WCA in solving LFC issues. Then, in order to identify the robustness of the closed-loop system, sensitivity analysis is carried out. Additionally, a two-area non-reheat unit was tested under the governor dead band nonlinearity. To guarantee the suitability of the proposed FPID controller, a model with a mixture of power plants, such as reheat, hydro, and gas unit in each area was carried out with and without the HVDC link, which can increase practical issues with LFC. The proposed controller's robustness was studied for all models under numerous scenarios, step load perturbations (SLP), and different objective functions. Simulation results proved that the proposed FPID controller provided superior performance compared to recently reported techniques in terms of peaks and settling time.

Frequency regulation of a RES integrated power system with AC/DC parallel link employing a fuzzy tuned fractional order controller

Abstract This paper demonstrates the operational efficacy of a newly proposed fuzzy tuned fractional order controller to offer an improved frequency regulation of a multi area renewable energy source (RES) integrated nonlinear power system. The effect of governor dead band nonlinearity and generation rate constraint of hydro and thermal power plants are considered in the system. Moreover, a proposed appropriate High voltage direct current (HVDC) tie line model is incorporated in this work, to verify the frequency deviation. Different test cases are applied to verify the robustness of the controllers on frequency response. The superiority of the proposed controller upon Proportional integral and derivative (PID), fuzzy logic controller and fuzzy PID controller in minimizing frequency deviation has been verified through MATLAB SIMULINK environment.

Design of new fractional order PI–fractional order PD cascade controller through dragonfly search algorithm for advanced load frequency control of power systems

Owing to integrating the dense range of distinct electric power sources, high volume of power generation units, abrupt and continuous changes in load demand, and rising utilization of power electronics, the electric power system (EPS) is striving for high-performance control schemes to counterwork the concerns depicted above. Additionally, it is highly creditable to have the controller structure as simple as possible from a viewpoint of practical implementation. Thus, this paper describes a virgin application of fractional order proportional integral–fractional order proportional derivative (FOPI–FOPD) cascade controller for load frequency control (LFC) of electric power generating systems. The proposed controller includes fractional order PI and fractional order PD controllers connected in cascade wherein orders of integrator ( $$\lambda$$ ) and differentiator ( $$\mu$$ ) may be fractional. The gains and fractional order parameters of the controller are concurrently tuned using recently proposed dragonfly search algorithm (DSA) by minimizing the integral time absolute error (ITAE) of frequency and tie-line power deviations. DSA is the mathematical model and computer simulation of static and dynamic swarming behaviors of dragonflies in nature, and its implementation in LFC studies is very rare, unveiling additional research gap to be bridged. Performance of the advocated approach is first explored on popular two-area thermal PS with/without governor dead band (GDB) nonlinearity and then on three-area hydrothermal PS with suitable generation rate constraints. To highlight the prominence and universality of our proposal, the work is extended to single-/multi-area multi-source EPSs. Several comparisons with DSA optimized FOPID controller and the relevant recent works for each test system indicate the contribution of proposed DSA optimized FOPI–FOPD cascade controller in alleviating settling time/undershoot/overshoot of frequency and tie-line power oscillations.

An Improved ACO Algorithm Optimized Fuzzy PID Controller for Load Frequency Control in Multi Area Interconnected Power Systems

In this paper, an Improved Ant Colony Optimization (IACO) algorithm optimized fuzzy PID (FPID) controller is proposed for Load Frequency Control of multi area systems. The nonlinear incremental evaporation rate and improvement of pheromone increment updating are proposed in the IACO algorithm to improve the quality of solution. And, a modified objective function using integral time multiply absolute error (ITAE), overshoot, undershoot and settling time with appropriate weight coefficients is proposed to improve the performance of the controller. Initially, a two-area non-reheat thermal system is applied and the FPID controller parameters are optimized by the IACO algorithm with five different objective functions. The modified objective function has better performances than four conventional objective functions. To demonstrate the robustness of the proposed control method, sensitivity analysis is implemented under wide variation of operating conditions and system parameters. Further, the proposed approach is also extended to two-area four-sources hydro thermal power system with/without High Voltage Direct Current (HVDC) link. The superiority of the proposed approach is shown by comparing the results with ZN, GA and hPSO-PS algorithms. The robustness of the proposed method is verified under random load disturbances. Finally, the proposed approach is extended to a two-area power system with governor dead band nonlinearity and results show that the proposed approach can cope with nonlinearity well. The results obtained from all simulations show that the proposed algorithm and modified objective function achieves better performances, such as minimum objective values (ITAE = 0.0255, ITSE = 9.30e-5, ISE = 1.91e-4 and IAE = 0.0273) obtained for the two-area non-reheat thermal system.

Improved stochastic fractal search algorithm and modified cost function for automatic generation control of interconnected electric power systems

An improved stochastic fractal search algorithm (ISFS) and a modified cost function are proposed in this paper to skillfully handle the issue of automatic generation control (AGC) of power systems. Most employed power system models namely two-area non-reheat thermal power system with and without governor dead band nonlinearity, and three-area hydro-thermal power plant with generation rate constraints are considered to be controlled by a PID controller. Then the gains of this controller are optimized with SFS and ISFS individually by minimizing the value of cost function proposed. This function consists in minimizing the integral time absolute error (ITAE) and also the time rates of frequency and tie-line power deviations. After recognizing the supremacy of SFS tuned PID controller over some existing methods in improving settling time and oscillations of frequency and tie-line power deviations, ISFS tuned PID controller is shown to promote the system performance further to compete with some other control schemes of higher degree and complexity available in the literature. This outcome has unveiled the superior tuning ability of ISFS over the original version of SFS. Also, convergence curves of the algorithms are analyzed from which it is observed that the speed of convergence for ISFS is remarkable.

Impact of Flexible AC Transmission System Devices on Automatic Generation Control with a Metaheuristic Based Fuzzy PID Controller

The present work proposes a teaching–learning-based optimization (TLBO)-tuned fuzzy proportional-integral-derivative (PID) controller of two-area hydro-thermal generating units for automatic generation control (AGC). The proposed system takes into account the physical constraints such as transport delay (TD), generation rate constraint (GRC), and governor dead band (GDB) nonlinearities. Firstly, fuzzy PID controllers were designed for both the areas and their gains were optimized using various minimization objective function criteria. Furthermore, applications of flexible alternating current transmission system (FACTS) devices such as static synchronous series compensator (SSSC), thyristor-controlled series capacitor (TCSC), thyristor-controlled phase shifter (TCPS), and unified power flow controller (UPFC) were investigated by integrating FACTS devices in appropriate locations of the system. The simulation results revealed that the minimum objective values were attained when the UPFC was placed in the system. Lastly, robustness analysis was done to observe the capability of the proposed controller with UPFC by changing system parameters and considering random load disturbances.

Effect of energy storage systems on automatic generation control of interconnected traditional and restructured energy systems

During major disturbances in electric power system (PS) penetrated with renewable energy sources, primary and supplementary automatic generation control (AGC) strategies usually show inefficiency in mitigating the frequency and power oscillations because of sluggish control action. The frequency and power deviations should be controlled to retain the generation-demand balance, which reinforce the quality and stability of overall PS. The fast-acting energy storage systems (ESSs) having very small time constants like capacitive energy storage (CES) and redox flow battery (RFB) are utilised in this study to improve these dynamic responses. To conduct the analysis, initially, a two-area nonreheat thermal PS with extra generations from wind turbine system (WTS) and dish-stirling solar thermal system (DSTS) is explored extensively, and then to validate the efficacy of the method, the approach is tested on two-area nonreheat thermal system having governor deadband (GDB) nonlinearity, reheat thermal, and restructured multisource thermal gas systems. An imperialist competition algorithm (ICA) optimised fuzzy PID-filter-(1 + PI) controller named as FPIDF-(1 + PI) is utilised as supplementary controller, and its performance with CES/CES-RFB is compared with ICA-optimised FPIDF with/without CES and existing optimal PI/PID/PIDF/FPID controller without CES. Investigation of dynamic responses for sudden variation in power demand unveils the superiority of the control approach compared with others regarding settling time, peak undershoot, and performance index. Analysing the impact of ESSs on the responses divulges that the amalgamation of CES-RFB in PS imparts better system dynamics. The robustness analysis suggests that ICA-optimised controller with ESSs performs excellently and robustly for ±25% variation in PS parameters, random load disturbances, and nonlinearities.

Differential evolution algorithm tuned tilt integral derivative controller with filter controller for automatic generation control

A differential evolution (DE) tuned tilt integral derivative controller with filter (TIDF) has been implemented to a multi area reheat thermal power system for automatic generation control by taking the physical constraints like generation rate constraint and governor dead band nonlinearity. Initially, dissimilar integral controllers are considered in each area and the integral controller gains have been optimized by integral of time multiplied by absolute value of error (ITAE) criterion exploiting different strategies of DE algorithm. In next step, the control parameters such as step size and crossover probability of DE for the best strategy can be chosen with multiple iterations of the algorithm systematically for variation in each control parameter and DE proposes the control parameters. Further, PI/PID/TIDF type controller schemes have been modified and their gains have been optimized by optimal DE. Furthermore, to improve the transient system response, TIDF controller coordinated unified power flow controller (UPFC) has been investigated. The simulation results reveal that the minimum ITAE value is obtained when UPFC is placed in area-5 only. Finally, sensitivity analysis has been done by changing the operating load conditions along with the time constants of system parameters, from the simulation results it has been examined that there is no need to reset the controller parameters from their nominal setting for these variations. The proposed control scheme effectiveness is also observed by considering random step load disturbance and sinusoidal load disturbance.

Improving the dynamic frequency regulation of a multisource power system considering GRC and dead band with TCSC and SMES

Coordinated operation of superconducting magnetic energy storage (SMES) and thyristor controlled series compensator (TCSC) for dynamic frequency regulation on a multisource power system is presented in this paper. The optimal integral gains of the control areas are obtained by tuning a quadratic performance index consisting of frequency deviations and tie-line power error using integral squared error technique. The effects of generation rate constraint and governor dead band nonlinearities are also considered. Time domain simulations carried out in MATLAB on a sample two area multi-unit power system comprising hydro, thermal and gas power plants reveal that the SMES-TCSC combination can effectively damp out deviations in area frequencies and tie-line power flow following a sudden load perturbation with better transient performance and reduced settling time.

Improving the dynamic frequency regulation of a multisource power system considering GRC and dead band with TCSC and SMES

Coordinated operation of superconducting magnetic energy storage (SMES) and thyristor controlled series compensator (TCSC) for dynamic frequency regulation on a multisource power system is presented in this paper. The optimal integral gains of the control areas are obtained by tuning a quadratic performance index consisting of frequency deviations and tie-line power error using integral squared error technique. The effects of generation rate constraint and governor dead band nonlinearities are also considered. Time domain simulations carried out in MATLAB on a sample two area multi-unit power system comprising hydro, thermal and gas power plants reveal that the SMES-TCSC combination can effectively damp out deviations in area frequencies and tie-line power flow following a sudden load perturbation with better transient performance and reduced settling time.

Comparative performance analysis of 2DOF state feedback controller for automatic generation control using whale optimization algorithm

SummaryThis paper presents the design of two‐degree‐of‐freedom state feedback controller (2DOFSFC) for automatic generation control problem. A recently developed new metaheuristic algorithm called whale optimization algorithm is employed to optimize the parameters of 2DOFSFC. The proposed 2DOFSFC is analyzed for a two‐area interconnected thermal power system including governor dead band nonlinearity and further extended to multiunit hydrothermal power system. The supremacy of the 2DOFSFC is established comparing with proportional‐integral, proportional‐integral‐derivative (PID), and 2DOFPID controllers optimized with different competitive algorithms for the concerned system. The sensitivity analysis of the optimal 2DOFSFC is performed with uncertainty condition made by varying bias coefficient B and regulation R parameters. Furthermore, the proposed controller is also verified against random load variations and step load perturbation at different locations of the system.

AGC of two-area electric power systems using optimized fuzzy PID with filter plus double integral controller

The incessant swell in size, complexity, nonlinearity and structural variations in modern electric power systems, as well as rise in power demand has entailed the use of intelligent control strategies for the real-time satisfactory operation of power system. Hence, in this paper, a novel fuzzy PID with filter plus double integral (FPIDF-II) controller is proposed for automatic generation control (AGC) of two-area interconnected power systems. Initially, a well accepted two-area non-reheat thermal system is considered and the output scaling factors (SF) of FPIDF-II controller are optimized using imperialist competitive algorithm (ICA) employing an integral squared error (ISE) criterion. The supremacy of the proposed approach is demonstrated by contrasting the results with recently published optimal and various modern heuristic optimization techniques based controllers. To demonstrate the efficacy and scalability of the approach over other prevalent intelligent control techniques, the study is further extended to two-area non-reheat thermal system with governor deadband nonlinearity, two-area reheat thermal system, recently appeared two-area photovoltaic (PV)-reheat thermal system and two-area multi-source hydrothermal system. Finally, a sensitivity analysis is carried out to demonstrate the robustness of the proposed controller under broad variations in the system parameters from their nominal values.

An effective hybrid harmony search and cuckoo optimization algorithm based fuzzy PID controller for load frequency control

In this paper, a hybrid algorithm is developed by incorporating the egg-laying and immigration mechanisms of cuckoo optimization algorithm (COA) into harmony search (HS) algorithm (HSCOA), to design a secondary controller for two practical models of load frequency control (LFC) problem. Initially, a two-area non-reheat thermal power system is considered and the gains of PID and fuzzy PI/PID controllers are adjusted by the proposed tuning method. The superiority of HSCOA in regulating controller gains is demonstrated by evaluation and comparison of the obtained transient outcomes over some other published approaches in literature. To prove the satisfaction of the robustness in designed LFC by means of the proposed method, the performance of HSCOA based fuzzy PID controller is extensively verified under varying loading condition and some critical parameters related to the considered power plant. To add further practical challenge, the governor dead band (GDB) is included in the concerned system modeling to study the advantages of the HSCOA tuned fuzzy PID controller in handling the properties of nonlinearity in the system model. Time domain simulation of transient responses indicates that the designed controller operates satisfactorily to deal with the GDB nonlinearity and outperform other published techniques. Furthermore, to demonstrate the effective feasibility of the proposed method, the study is extended to a two-area multi-source power system with/without consideration of HVDC link. It is observed that HSCOA optimized fuzzy PID controller gives superior quality outcomes in comparison to other reported strategies. Finally, the robustness of the controller’s gains designed for the concerned power system is investigated under various scenarios of change in size, location and pattern of step load perturbation.

Integrating a superconducting magnetic energy storage system for intelligent control of LFC characteristic in multi-area power system

This work exhibits use of adaptive neural control configured genetically tuned PI controller based superconducting magnetic energy storage (SMES) system for enhanced load frequency control (LFC) operation for a three area power system. The suggested scheme for the SMES control is a distinct one, as it overcomes the shortcomings in the contemporary SMES control schemes with automatic adjustment of converter duty ratio. Control in each area is accomplished via a neural estimator and a neural controller online simultaneously. The neural estimator selects the control area dynamics over a functioning zone, this feature leads to pure adaptive control, with modified gain settings obtained by integral square error criterion (ISE). Simulation studies carried out on MATLAB are presented for the power system with steam reheat constraint and governor dead band nonlinearity, after carrying out necessary modelling exercise, which portrays a reduction of 65% and 50% overshoots in frequency and tie-power oscillations respectively.

Novel approach to Automatic Generation Control with various Non-linearities using 2-degree-of-freedom PID controller

In the proposal for modern power systems with automatic generation control (AGC) the controller suggested is, a Two- Degree-of-Freedom PID (2-DOF-PID) controller. The proposed controller, for the first time, is tested on two unequal area thermal systems considering boiler dynamics as well as governor dead band non-linearity. The concurrent optimization of numerous parameters of the controllers is achieved by Differential Evolution Algorithm (DE) and the Integral Time Absolute Error (ITAE) is the implemented objective function. Experimental result evidently conceals the dominance of the 2-DOF-PID controller considering transient behaviour and time required for stabilizing the system. Current research analyse the usefulness of the Differential Evolution algorithm as a technique for deriving the optimum controller parameter values. Sensitivity analysis for diverse load settings justifies sturdiness of 2-DOF-PID controller. Furthermore, the simple PID controller used abundantly in industries is compared with the of the performance of proposed controller.

Load Frequency Control of Power Systems with Governor Deadband (GDB) Non-linearity

Load frequency control of power systems with a governor deadband (GDB) is studied in the paper. The effects of GDB on the linear active disturbance rejection controller (LADRC) are analyzed first. It is shown that the limit cycle can be avoided by reducing the controller and/or observer bandwidth. However, the disturbance rejection performance will be degraded. To maintain the performance of the original LADRC controller, two anti-GDB schemes are proposed. One is based on the observer structure of active disturbance rejection control, which utilizes the output of the governor to reconstruct the input to the system in order to correctly estimate the controller states. Another is based on the error between the realistic output of the governor and its ideal value which is fed back and added to the output of the original LADRC. Simulation results on a single-area and a two-area power system with the GDB show that the two schemes are effective in reducing the limit cycle caused by the GDB. The observer-based anti-GDB has some limitations in practical implementation and performance, while the error-compensation-based scheme is simple to implement and can approximate the disturbance rejection performance of the original LADRC.

Differential evolution algorithm based tilt integral derivative control for LFC problem of an interconnected hydro-thermal power system

Conventional control techniques such as proportional integral (PI) control and proportional integral derivative (PID) control are widely used as the load frequency controller in power system control applications; however, the increase in complexity of the power system is degrading the performance of classical control. Therefore, in this paper a new control approach using fractional calculus has been proposed for the load frequency control problem of two-area hydro-thermal power system. The paper presents an interconnected hydro-thermal power system working under different operating conditions introduced in the form of various nonlinearities. Four case studies have been presented in this paper considering transient analysis with (i) different loading conditions, (ii) parameter variations, (iii) different nonlinearities (governor dead band nonlinearity, time delay and generation rate constraints), and (iv) superconducting magnetic energy storage (SMES) device. A tilt integral derivative (TID) control has been presented as a secondary controller to stabilize the frequency deviations occurring in the two-area power system with the above-mentioned different operating conditions. The parameters of TID controller have been optimized using a differential evolution algorithm which solves an optimization problem formulated using the integral of time-weighted absolute error (ITAE) performance index. In addition, a comparison of dynamic system response obtained using TID control and PID control has been presented, which focusses on the better performance of TID control over PID control in an interconnected power system.

A flower pollination algorithm based automatic generation control of interconnected power system

Abstract This paper presents the design and performance analysis of Flower Pollination Algorithm (FPA) based Proportional Integral Derivative (PID) controllers for Automatic Generation Control (AGC) of an interconnected power system. A two area thermal system with governor dead-band nonlinearity is considered for the design and analysis purpose. A different kind of approach is made to design a multi-objective function which contains weighted performance functions such as ISE, IAE, ISTE, ITAE. These weights are the functions of system response. It is noticed that the dynamic performance of new objective optimized PID controller is better than the others mentioned in the literature. The objective function also includes performance response for various percentage of loads, so that obtained gain parameters are optimal for dynamic load conditions.