Generator Excitation Control Research Articles

Flatness-based adaptive fuzzy output tracking excitation control for power system generators

In this paper, a novel approach for the design of an indirect adaptive fuzzy output tracking excitation control of power system generators is proposed. The method is developed based on the concept of differentially flat systems through which the nonlinear system can be written in canonical form. The flatness-based adaptive fuzzy control methodology is used to design the excitation control signal of a single machine power system in order to track a reference trajectory for the generator angle. The considered power system can be written in the canonical form and the resulting excitation control signal is shown to be nonlinear. In case of unknown power system parameters due to abnormalities, the nonlinear functions appearing in the control signal are approximated using adaptive fuzzy systems. Simulation results show that the proposed controller can enhance the transient stability of the power system under a three-phase to ground fault occurring near the generator terminals.

Extended Backstepping Method for Single-Machine Infinite-Bus Power Systems With SMES

This brief studies the stability of single-machine infinite-bus power systems with superconducting magnetic energy storage (SMES) via simultaneous design of generator excitation control and SMES control. Since the object model is of non-strict-feedback form and thus the traditional backstepping method is not applicable, we propose an extended backstepping method for a class of general nonlinear systems. Then, we apply the proposed method to the object model and design the generator excitation controller and SMES controller simultaneously, which stabilize the power angle, the generator terminal voltage, and the power oscillation. In addition, we improve the transient and steady-state performances of power systems by introducing class <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> functions in the design process. Simulation results also show the effectiveness and advantage of the proposed controller.

Predictive Synchronous Generator Excitation Control Based on Laguerre Model

In this paper the synchronous generator excitation control is designed using the model reference control approach and its predictive extension. The control objective is to satisfy requirements on the synchronous generator performances imposed by the transmission system operator. The structure of both controllers is expressed in the form of modified Laguerre network. The efficiency of the proposed control design procedure is illustrated by simulation of the 259 MVA synchronous generator of the nuclear power plant Mochovce in Slovakia.

H ∞ control of single‐machine infinite bus power systems with superconducting magnetic energy storage based on energy‐shaping and backstepping

This article studies the H∞ control problem for single-machine infinite bus power systems with superconducting magnetic energy storage (SMES) via simultaneous design of generator excitation control and SMES control. In the control system design, the exciter dynamics and unknown external disturbances are considered for practical implementation in power systems. A new synthesis framework is proposed to address the robust control problem of power systems with SMES. First, from the energy perspective, the interconnection and damping assignment (IDA) approach is applied to improve the transient performance of power systems. Second, by introducing the idea of virtual control in the design process, the authors obtain the solution of a partial differential equation that is a crucial point and cannot be obtained by using the traditional IDA method. Third, in order to enhance the robustness of the closed-loop system, the authors study the H∞ control design that is challenging and difficult for power systems considering the above mentioned practical considerations. In addition, the authors use a novel equivalent generator model to avoid using unmeasurable infinite bus voltage. Simulation results also show the effectiveness and advantage of the proposed controller.

Research on DSP-Based Automatic Excitation Regulator in Small Rural Hydropower Station

Excitation regulator has played an important role to ensure that generator run safely and stably. However, in some remote areas, the rural small generator excitation control system is very backward, and it has hindered the development of Chinese agriculture and the pace of new countryside construction. This paper introduced a kind of structure and basic principle of DSP-based automatic excitation regulator, which was applied to rural small generator. We chose TMS320LF2407A chip as the core of regulator control system; the regulator adjusted PWM based on PID control strategy to control the exciting current. The theoretical analysis showed that the regulator had the characteristics of simplicity and reliability, well dynamic and static characteristics, and it could also adjust its own state quickly. The result was applicable to small rural hydropower station.

Automatic excitation control of synchronous generators as an effective means to ensure the reliable parallel operation of generation equipment and the united power system as a whole

The reliability of the parallel operation of generation equipment and the functioning of the power system as a whole depends on the effectiveness of automatic excitation regulators (AER) and excitation systems (ES) of synchronous generators at power plants. The SO-UPS elaborated, approved, and enforced the standard Requirements to Excitation Systems and Automatic PD Excitation Regulators of Synchronous Generators, which extends and supplements the requirements to ESs and AERs established by the technical regulations currently in force. A system regulators monitoring system is being developed.

Nonlinear Prediction Control of Synchronous Generator Excitation Based on Subsection Approximation

This paper presents a subsection approximate nonlinear model predictive control (SANMPC) method for synchronous generator excitation control in the regional power grid. The proposed SANMPC considers the voltage as the reference trajectories and the change range of active power, reactive power and voltage as unequal constraints. Segmenting for a sampling interval, it uses sampled values and the control input initial value at the current sampling moment to predict the state at each segment by the Explicit Euler method. The predictive equations of the next sampling moment can be obtained by the predictive state and the control input at the penultimate segment, and form the optimal control problem which may be solved by the interior-point method. We take advantage of a four-machine power system to verify the effectiveness of the proposed SANMPC method under MATLAB platform. The simulating results show that the SANMPC method is simple and efficient, and greatly improves the transient stability compared with the conventional controller both.

A Summary on Algorithm Research of Synchronous Generator Excitation Control

To solve the problem that in excitation control system the parameters of proportional integral differential (PID) controller are difficult to be set, a summary on research results of current synchronous generator excitation control regulator parameters optimization. The article details the PSO algorithm of synchronous generator excitation control principles, and whose advantages and disadvantages. For the PSO algorithm converges slower early and late defects iteration, it introduces a new algorithm called adaptive chaotic particle swarm optimization (CAPSO), and using the chaotic tent mapping-based search methods to achieve improvements in partly-search, with a strong and robust search capabilities for the industry and scholars for reference.

Models of generator excitation control systems in dynamic security analyses of electric power interconnections

This paper presents models of generator excitation control systems used in dynamic security analyses of electric power interconnections. The general structure and functional block diagram of generator excitation control systems are given, as well as a review of the current state within the electrical power system of Serbia. The model used for analyses of short-term dynamics where transient stability analyses are dominant, has been presented. The model used in the analyses of long-term dynamics, has also been presented. After verification based on experimental measurements, these models have been incorporated into appropriate computer programs for dynamic security analyses of electric power interconnections. These computer programs have been developed at the 'Nikola Tesla' Institute and some typical examples of their application have been provided.

Forming of Simplified Forms of Synchronous Generator Excitation Control Algorithms and comparison of their efficiency

The problem of effective electromechanic transients damping and power system stability may be solved by using automatic voltage regulators (AVR). Novel microprocessor AVR sometimes use well-known algorithms, which were designed for analog regulators. This paper continues the study of presented before algorithms based on Bellman derivative equation. Some simplifications of the proposed excitation control algorithms are presented. Topology-based correction of algorithms is mentioned.

Decentralized H ∞ control for damping power system oscillations

Abstract Inter-area oscillations are serious problems to large-scale power systems. A decentralized H ∞ generator excitation controller of a power system is proposed to damp the inter-area oscillations and to enhance power system stability. The design procedure for a linear composite system is presented in terms of positive semi-definite solutions to modified algebraic inequalities. The resulting controller guarantees closed-loop stability, robustness and an H ∞-norm bound on disturbance attenuation even under uncertainties such as high frequency noise. The control is decentralized in the sense that the control of each generator depends on local information only. The effectiveness of the H ∞ controller is demonstrated through digital simulation studies on a two-machine power system.

The Excitation Controller for A Synchronous Generator Based on Nonlinear Optimal Control

A nonlinear optimal controller for excitation control of synchronous generators is presented. Based on differential geometry theory, the controller is designed by transforming the nonlinear system to an equivalent linear system. The analysis and simulation of a single-machine infinite-bus power system indicate that the stability of the proposed controller better than the stability of conventional linear controllers

Research on Small Synchronous Generator Excited System Based on Fuzzy Control

This article describes the small synchronous generator excitation control device characteristics and working principle is proposed based on fuzzy control of excitation regulator device on-site test method. Phase compound excitations with voltage corrector by the way of magnetic amplifier were used in excitation devices. The generator terminal voltage, load current and power factor and other parameters were adjusted by fuzzy control through automatic control phase compound excitation transformer. For separate generator, the major factor of terminal voltage change was caused by the change of reactive current, in order to keep constant voltage generator excitation current mast be adjusted. At the end of the paper the problems and countermeasures in the course of debugging process were analyzed.

A Hybrid Intelligent Excitation Control for Ship Power Station

Hybrid intelligent control technique is used for ship power station synchronous generator excitation control in this paper. The parameters and structure of the excitation controller are learned and adjusted through a hybrid learning algorithm combining self-organizing learning with BP learning. This algorithm converges much faster than original BP learning. Simulation results show that the synchronous generator excitation controller based on the learning algorithm can significantly stabilize terminal voltage.

Nonlinear multi‐index coordinated control of generator excitation and battery energy storage system

SUMMARYThe strong nonlinear nature of the generator and system behavior following a severe disturbance precludes the use of classical linear control techniques. The integration of an energy storage system, such as battery energy storage system (BESS), into a flexible alternating current transmission system device can provide dynamic decentralized active power capabilities and much needed flexibility for mitigating transmission level power flow problems. A model of power system with BESS compensation devices that integrate classic third‐order model of generator and BESS model was deducted and established in this paper. The BESS unit is located near the generator bus terminal in a power system. Using multi‐index nonlinear control design method, BESS and generator excitation were designed by coordinate control scheme for the model above. The controller proposed in this paper is good in improving the dynamic characteristics of state variables, so as to enhance the stable operation capacity of the system. The simulation on single‐machine infinite‐bus power system demonstrates the effectiveness and the practicality of the controller. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Power System Stabilization Using Adaptive Neural Network-Based Dynamic Surface Control

In this paper, the power system with an excitation controller is represented as a class of large-scale, uncertain, interconnected nonlinear continuous-time system in strict-feedback form. Subsequently, dynamic surface control (DSC)-based adaptive neural network (NN) controller is designed to overcome the repeated differentiation of the control input that is observed in the conventional backstepping approach. The NNs are utilized to approximate the unknown subsystem and the interconnection dynamics. By using novel online NN weight update laws with quadratic error terms, the closed-loop signals are shown to be locally asymptotically stable via Lyapunov stability analysis, even in the presence of NN approximation errors in contrast with other NN techniques where a bounded stability is normally assured. Simulation results on the IEEE 14-bus power system with generator excitation control are provided to show the effectiveness of the approach in damping oscillations that occur after disturbances are removed. The end result is a nonlinear decentralized adaptive state-feedback excitation controller for damping power systems oscillations in the presence of uncertain interconnection terms.

An improved direct feedback linearization technique for transient stability enhancement and voltage regulation of power generators

In this paper, a simple improved direct feedback linearization design method for transient stability and voltage regulation of power systems is discussed. Starting with the classical direct feedback linearization technique currently applied to power systems, an adaptive nonlinear excitation control of synchronous generators is proposed, which is new and effective for engineering. The power angle and mechanical power input are not assumed to be available. The proposed method is based on a standard third-order model of a synchronous generator which requires only information about the physical available measurements of angular speed, active electric power and generator terminal voltage. Experimental results of a practical power system show that fast response, robustness, damping, steady-state and transient stability as well as voltage regulation are all achieved satisfactorily.

Stability analysis of a generator excitation control system with time delays

This paper investigates the effect of time delays on the stability of generator excitation control system. The time delays are due to the use of measurement devices, communication links for data transfer, and controller processing time. The stability with respect to the time delay is theoretically analyzed and a formula to determine the maximum amount of time delay known as delay margin that the system can tolerate without losing its stability is presented. It is found that the excitation control system becomes unstable when the time delay crosses certain critical values, delay margins for stability. The time-domain simulations of Matlab/Simulink are used to validate theoretical delay margin results.

Damping of system oscillatory modes by a phase compensated gas turbine governor

The proliferation of gas turbines in power systems increases the scope for taking advantage of mechanical torque control for improved network damping. This paper describes a phase compensated governor for a gas turbine and explores its potential contributions to system damping in a multimachine context. It is shown that the inclusion of phase compensation in the governor control loop is capable of achieving dynamic stability for the system without the need of a power system stabilizer (PSS) in the generator excitation control loop and without adversely influencing terminal voltage control. In addition, it is demonstrated that a phase compensated governor (PCG) is also capable of significantly improving transient stability and by complementing the effectiveness of a conventional PSS, enables a superior overall contribution to network damping.

Adaptive H-infinity control of synchronous generators with steam valve via Hamiltonian function method

Based on Hamiltonian formulation, this paper proposes a design approach to nonlinear feedback excitation control of synchronous generators with steam valve control, disturbances and unknown parameters. It is shown that the dynamics of the synchronous generators can be expressed as a dissipative Hamiltonian system, based on which an adaptive H-infinity controller is then designed for the systems by using the structure properties of dissipative Hamiltonian systems. Simulations show that the controller obtained in this paper is very effective.