Design Of Power Control System Research Articles

QFT based Robust Load Frequency Controller Design for Multi-Area Power System

QFT based Robust Load Frequency Controller Design for Multi-Area Power System

An Adaptive Sliding Mode Controller Design for Power Systems with STATCOM

The main purpose of this paper is to present a simple design strategy to synthesize an adaptive sliding controller capable of stabilizing an electric power system with static synchronous compensator (STATCOM) and improving the transient stability of the system. In this study, the developed control scheme is tested on a single-machine infinite bus (SMIB) power system with STATCOM and some unknown parameters in the face of a symmetrical three-phase short circuit fault. Simulation results show that in spite of having a simple design procedure, the developed controller offers better transient performances in comparison with some existing nonlinear controllers.

Decentralized adaptive controller design for large-scale power systems

This paper proposes a novel decentralized adaptive excitation control scheme to globally stabilize large-scale power systems and enhance the transient stability. Two smooth functions are introduced to counteract the effect of unknown time-varying interactions, then a completely decentralized adaptive controller is constructed on the basis of the adaptive backstepping approach. The proposed controller utilizes only local measurements and has no requirement for the bounds of interconnections in the power system. All signals of the overall closed-loop large-scale power system are proved to be globally uniformly bounded. The proposed control scheme is tested on a two-area benchmark power system in the face of a symmetrical three-phase short circuit fault. Simulation results have showed better transient performances in comparison with existing controllers.

Recurrent ANFIS-Coordinated Controller Design for Multimachine Power System with FACTS Devices

This paper proposes the design of auxiliary-coordinated controller for static VAR compensator (SVC) and thyristor-controlled series capacitor (TCSC) devices by adaptive fuzzy optimized technique for oscillation damping in multimachine power systems. The performance of the coordinated control of SVC and TCSC devices based on feedforward adaptive neuro fuzzy inference system (F-ANFIS) is compared with that of the adaptive neuro fuzzy inference system (ANFIS) structure based on recurrent adaptive neuro fuzzy inference system (R-ANFIS) network architecture. The objective of the coordinated controller design is to tune the parameters of SVC and TCSC fuzzy lead lag compensator simultaneously to minimize the deviation of rotor angle and rotor speed of the generators. The performance of the system is enhanced by optimally tuning the membership functions of fuzzy lead lag controller parameter of the flexible AC transmission system (FACTS) by R-ANFIS controller. The training data for F-ANFIS and R-ANFIS are generated by conventional linear control technique under various operating conditions. The offline trained controller tunes the parameter of lead lag controller in online. The oscillation damping ability of the system is analyzed for three-machine test system by calculating the standard deviation and cost function. The superior performance of R-ANFIS controller is compared with various particle swarm optimization-based feedforward ANFIS controllers available in literature.

Non‐linear adaptive coordinated controller design for multimachine power systems to improve transient stability

Based on an adaptive backstepping approach, this study proposes a new coordinated control design where the coordination is done between the excitation controller of synchronous generators and steam-valve controller of turbine-governor systems in a multimachine power system by considering the critical parameters of both systems as unknown. This new coordinated control scheme can ensure the stability of multimachine power systems through the formulation of control Lyapunov functions (CLFs) and derive the adaptation laws to estimate the unknown parameters in the design process to prove the convergence of power systems using CLFs. The performances of the proposed control scheme are evaluated on a two-area four-machine 11-bus power system under different operating conditions such as three-phase short-circuit faults along with changes in loads. Simulation results are then compared with those of a similar controller where there is no coordination between the excitation and steam-valve controllers as well as with a coordinated sliding-mode controller. The results clearly show the effectiveness and superiority of the proposed control scheme.

Coordinated control design for a PEMFC power system using adaptive VRFT method

For a proton exchange membrane fuel cell (PEMFC) power system containing a methanol reformer and a DC–DC converter, it is necessary to coordinate the subsystem controllers to achieve effective power tracking control and prevent constraint violations. This study focuses on the controller design of coordinating control scheme for a PEMFC power system to maintain stable fuel utilization ratio and meet the load demand simultaneously. Because the system exhibits considerable nonlinear behavior, a process model is difficult to identify and is prone to modeling errors. Therefore, this study employs the virtual reference feedback tuning (VRFT) method to design the controllers directly using the process input–output data. To address the process nonlinearity, an improved adaptive VRFT method is developed and applied to the adaptive PID controllers design for a cascade control system. Furthermore, the design parameter of the fuel cell current controller is adaptively tuned according to the deviation of fuel utilization ratio, so that the coordinating control is realized by keeping the dynamics of the current loop consistent with that of the fuel flow loop. Simulation results show that this coordinated control design enables the PEMFC power system to track the load power demand effectively while maintaining the fuel utilization ratio constant.

Optimal Adaptive Controller Based on STATCOM and UPFC

In this paper, an advanced and modified MRAS technique is utilized for controller design in electric power systems. The weighting factors of the proposed MRAS are tuned by using PSO. This optimal-adaptive controller is also normalized by normalization techniques to guarantee the system stability. The proposed MRAS then is applied to design STATCOM stabilizer and UPFC power flow controller. STATCOM stabilizer is a regulatory controller, while the power flow controller of UPFC is a tracking one. Therefore, the ability of the proposed MRAS technique to design regulatory and tracking controllers is investigated. In order to indicate the effectiveness of the proposed method, it is evaluated against the conventional methods. Simulation results demonstrate the validity of the method, under uncertainties and different disturbances.

Nonlinear Adaptive Controller Design for Power Systems with STATCOM via Immersion and Invariance

In this paper, a nonlinear adaptive control of generator excitation and Static Synchronous Compensator (STATCOM) is proposed to enhance the transient stability and voltage regulation of an electrical power system. The proposed controller is designed via an adaptive immersion and invariance (I&I) methodology. In particular, a nonlinear model of the power system including two unknown constant parameters, namely an unknown damping coefficient and an unknown perturbation in mechanical power, is considered. It will be shown that the adapive I\&I control law and the parameter adaptation law proposed can accomplish the convergence of the system states to the real value of unknown parameters. Additionally, they can achieve transient stabilization along with voltage regulations. The adaptive I&I controller is validated using a simulation study on a single-machine infinite bus (SMIB) power system and compared with the standard I&I controller and an adaptive backstepping controller. Simulation results are given to indicate the effectiveness of the proposed controller for the transient stabilization and voltage regulation.

Delay-Dependent Stability Control for Power System With Multiple Time-Delays

Time-delay exists widely in electric power systems, and is found to have significant effect on the performance of operation and control under certain conditions. It is shown that even a very small delay may destabilize the power system. Therefore, time-delay is of important concern and should be properly handled, especially in the wide-area measurement and control environment. However, only few results about the controller design for power system considering multiple time-delays are reported. In this paper, a multiple time-delayed power system model is constructed with power system stabilizer (PSS) considering time-delays. By using Lyapunov stability theory and linear matrix inequality (LMI) method, two $H_{\infty}$ control schemes are developed for time-varying multiple delayed systems. The proposed controllers guarantee the closed-loop system asymptotic stable with $H_{\infty}$ performance. A two-area four-machine power system and the New England 10-machine 39-bus system are employed to demonstrate the effectiveness of proposed methods. The simulation results verify that the designed controllers can improve the control performance significantly.

Anti-Windup Load Frequency Controller Design for Multi-Area Power System with Generation Rate Constraint

To deal with the problem of generation rate constraint (GRC) during load frequency control (LFC) design for a multi-area interconnected power system, this paper proposes an anti-windup controller design method. Firstly, an H ∞ dynamic controller is designed to obtain robust performance of the closed-loop control system in the absence of the GRC. Then, an anti-windup compensator (AWC) is formulated to restrict the magnitude and rate of the control input (namely power increment) in the prescribed ranges so that the operation of generation unit does not exceed the physical constraints. Finally, the anti-windup LFC is tested on the multi-area interconnected power systems, and the simulation results illustrate the effectiveness of the proposed LFC design method with GRC.

Diversity increasing methods in PBIL-application to power system controller design: a comparison

Population-based incremental learning (PBIL) has recently received increasing attention due to its effectiveness, easy implementation and robustness. Despite this, recent literature suggests that PBIL may suffer from issues of loss of diversity in the population, resulting in premature convergence. In this paper, three diversity maintaining PBIL methods are proposed to address the issue of loss of diversity in PBIL. The first method uses an adaptive learning rate as opposed to the fixed learning rate that is normally used in the standard PBIL. In this method, the learning rate is adapted according to the degree of evolution of the search space. That is, the learning rate is increased linearly with the number of generation. The second method uses two sub-populations and conduct independent search in parallel with the same initial probability vectors, but with fixed learning rates similar to the one used in the standard PBIL. In the third method, the concept of duality or opposition is combined with parallel PBIL as a means of controlling the diversity in the population. To evaluate the performances of these methods, they are applied to the problem of controller design in power systems to improve the small-signal stability. Simulations results show that the proposed diversity maintaining methods are able to maintain the diversity in the population longer than the standard PBIL. However, PBIL with adaptive learning rate takes a little bit time to converge (more function evaluations) compared to the other methods.

Optimal and suboptimal controller design for wind power system

Wind power is a cost-effective renewable source and can be smoothly integrated into power grid by incorporating adequate control strategies. The wind turbine prime mover, wind, is uncontrollable which makes it different from conventional generation. Therefore, it becomes very important to carry out investigations on the dynamic behavior of wind power-generating systems. In this paper, the state space model of the system is developed, optimal controllers using full-state feedback control strategy and suboptimal controllers using strip eigenvalue assignment method are designed to study the dynamic behavior of the system. Also, the optimal controllers are designed for various operating conditions using pole placement technique. Following the controller designs, the closed-loop system eigenvalues and dynamic response plots are obtained for various system states considering various operating conditions. The investigations of these reveal that the implementation of optimal controllers offers not only good dynamic performance, but also ensures system dynamic stability.

Development of Wide-Area Measurement based Adaptive Controller Design for Power System Damping

Development of Wide-Area Measurement based Adaptive Controller Design for Power System Damping

A New Iterative Identification and Control Method of Closed-Loop Power System Based on Ambient Signals

Identification and control are important problems of power system based on ambient signals. In order to avoid the model error influence of the controller design, a new iterative identification and control method is proposed in this paper. This method can solve model set and controller design of closed-loop power system. First, an uncertain model of power system is established. Then, according to the stability margin of power system, stability theorem is put forward. And then controller design method and the whole algorithm procedure are given. Simulation results show the effective performance of the proposed method based on the four-machine-two-region system.

Hybrid Excavator Power System Controller Design Based on Fuzzy Control

Hybrid Excavator Power System Controller Design Based on Fuzzy Control

Feedforward-Feedback Control of a SOFC Power System: A Simulation Study

Smooth and timely control actions improve the efficiency and durability of solid oxide fuel cell (SOFC) power systems. In this paper a systematic feedforward-feedback approach to control design for SOFC power systems is proposed. The control aim is to regulate the temperature of and the temperature difference over the stack by manipulating the air flow, air inlet temperature and fuel flow. The feedforward part responds to the demanded electrical current and stoichometry of reforming and electrochemical processes. It gives the fuel flow rate needed to achieve the required stack current with a given fuel utilization. The air flow rate is then calculated according to the oxygen consumption in fuel cells and a given air utilization. Feedforward control is combined with the feedback control to adjust the manipulated variables based on the measured system output. Relative gain array (RGA) analysis (Shinskey, 1988) is performed over the system inputs and outputs (I/O) to determine optimal I/O pairing for control. The RGA is calculated from the static gain matrix of the SOFC stack model (Sorrentino et al., 2008). The strongest interactions are found between the cathode outlet temperature and the cathode inlet temperature, the stack temperature difference and the air flow rate, and the stack voltage and the fuel flow rate. Fuel flow rate has a strong influence also on the stack temperature and can be in some situations used to support temperature control. Based on the RGA analysis, two individual PI control loops are determined. In the first loop, the cathode outlet temperature is controlled by the proportional-integral (PI) controller that uses the cathode inlet temperature as the manipulated variable. In the second loop, the stack temperature difference is controlled by the PI controller with the air flow rate as the manipulated variable (see Figure 1). Altogether the control system consists of two PI control loops, making it feasible for practical implementation. The control target is similar as in (Pohjoranta et al., 2015) but it is obtained here with a significantly simpler approach. Anti-windup protection is included in the PI controllers to avoid long settling times caused by the limits on the manipulated variables (Peng et al, 1999). Parameters of the PI controllers are tuned from the open-loop step response experiments by applying the Magnitude Optimum Multiple Integration (MOMI) method (Vranèiæ et al., 1999). The feedforward-feedback control is evaluated on the SOFC stack model (Sorrentino et al., 2008) over a one-day operation cycle using the standard load profile of residential houses (Knight and Ribbering, 2007). The proposed feedforward-feedback control provides good control of the stack temperatures (see Figure 2). Relatively high stack voltage changes are caused by the significant load changes, however, but these can be reduced by combining a SOFC power system with an energy buffer. References Knight, I., Ribbering, H. (eds.) (2007). European and Canadian non-HYAC Electric and DHW Load Profiles for Use in Simulating the Performance of Residential Cogeneration Systems. A Report of Subtask A of FC+COGEN-SIM: The Simulation of Building-Integrated Fuel Cell and Other Cogeneration Systems. Peng Y., Vrancic D., Hanus R. (1996). Anti-windup, bumpless, and conditioned transfer techniques for PID controllers. Control syst. mag., 16, 48-57. Pohjoranta, A., Halinen, M., Pennanen, J., Kiviaho, J. (2015). Model predictive control of the solid oxide fuel cell stack temperature with models based on experimental data. Journal of Power Sources, 277, 239-250. Shinskey, F.G. (1988). Process control systems. 3rdedition. McGraw-Hill, New York. Sorrentino, M., Pianese, C., Guezennec, Y.G. (2008). A hierarchical modeling approach to the simulation and control of planar solid oxide fuel cells. Journal of Power Sources, 180, 380-392. Vrancic, D., Peng, Y., Strmcnik, S. (1999). A new PID controller tuning method based on multiple integrations, Control Engineering Practice, 7(5), 623-633. Figure 1

Differential Flatness Using the Predictive Neural Network Control Law for Hybrid Power System

In this paper, a control design for a renewable energy hybrid power system that is fed by a photovoltaic (PV), Wind turbine (WT) and fuel cell (FC) sources with a batteries (Batt) storage device is presented. The energy generated is managed through a nonlinear approach based on the differential flatness property. The control technique used in this work permits the entire description of the state’s trajectories, and so to improve the dynamic response, stability and robustness of the proposed hybrid system by decreasing the static error in the output regulated voltage. The control law of this approach is improved using the predictive neural network (PNN) to ensure a better tracking for the reference trajectory signals. The obtained results show that the proposed flatness-PNN is able to manage well the power flow in a hybrid system with multirenewable sources, providing more stability by decreasing the perturbation in the controlled DC bus voltage.

Cuckoo Search algorithm based load frequency controller design for nonlinear interconnected power system

Abstract A new optimization technique called Cuckoo Search (CS) algorithm for optimum tuning of PI controllers for Load Frequency Control (LFC) is suggested in this paper. A time domain based-objective function is established to robustly tune the parameters of PI-based LFC which is solved by the CS algorithm to attain the most optimistic results. A three-area interconnected system is investigated as a test system under various loading conditions where system nonlinearities are taken into account to confirm the effectiveness of the suggested algorithm. Simulation results are introduced to show the enhanced performance of the developed CS based controllers in comparison with Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and conventional integral controller. These results denote that the proposed controllers offer better performance over others in terms of settling times and various indices.

Saturated robust power system stabilizers

Abstract In this paper, a new saturated control design for uncertain power systems is proposed. The developed saturated control scheme is based on linear matrix inequality (LMI) optimization to achieve prescribed dynamic performance measures, e.g., settling time and damping ratio. In this design, the closed-loop poles are forced to lie within a desired region. The proposed design provides robustness against system uncertainties. The simulation results of both a single machine infinite bus and a multi-machine power systems are given to validate the effectiveness of the proposed controller.

A Robust Decentralized Controller Design for Interconnected Power System with Random Load Perturbations using SDO Software

Abstract Because of increase in load, size and change in power system structure, the response of load frequency control problem of the interconnected power system is more complex. This paper deals with Load Frequency Control of three area interconnected Power system having Reheat, Non-reheat and Reheat turbines in all areas respectively. The response of the load frequency control problem in a multi-area interconnected power system is improved by designing a PID controller using different tuning techniques and proved that the proposed controller, which was designed by Simulink Design Optimization Software gives the superior performance than other controllers for both Step load and Random load perturbations. Finally the validity and robustness of the proposed controller was checked against various Step load and Random load perturbations.