scholarly journals Computation of Stability Delay Margin of Time-Delayed Generator Excitation Control System with a Stabilizing Transformer

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Saffet Ayasun ◽  
Ulaş Eminoğlu ◽  
Şahin Sönmez
Keyword(s):  
Control System ◽  
Time Delay ◽  
Characteristic Equation ◽  
Time Delays ◽  
System Stability ◽  
Imaginary Root ◽  
Excitation Control ◽  
Wide Range ◽  
Generator Excitation Control ◽  
Delay Margin

This paper investigates the effect of time delays on the stability of a generator excitation control system compensated with a stabilizing transformer known as rate feedback stabilizer to damp out oscillations. The time delays are due to the use of measurement devices and communication links for data transfer. An analytical method is presented to compute the delay margin for stability. The delay margin is the maximum amount of time delay that the system can tolerate before it becomes unstable. First, without using any approximation, the transcendental characteristic equation is converted into a polynomial without the transcendentality such that its real roots coincide with the imaginary roots of the characteristic equation exactly. The resulting polynomial also enables us to easily determine the delay dependency of the system stability and the sensitivities of crossing roots with respect to the time delay. Then, an expression in terms of system parameters and imaginary root of the characteristic equation is derived for computing the delay margin. Theoretical delay margins are computed for a wide range of controller gains and their accuracy is verified by performing simulation studies. Results indicate that the addition of a stabilizing transformer to the excitation system increases the delay margin and improves the system damping significantly.

Delay margin computation of generator excitation control system by using fractional order controller

2020 ◽  
Vol 42 (13) ◽  
pp. 2465-2474
Author(s):  
Halil Erol
Keyword(s):  
Control System ◽  
Time Delay ◽  
Fractional Order ◽  
Pid Controller ◽  
Excitation Control ◽  
Proportional Integral Derivative ◽  
Proportional Integral Derivative Controller ◽  
Proportional Integral ◽  
Generator Excitation Control ◽  
Delay Margin

This article is devoted to stability analysis of generator excitation control system that has some time delay with fractional order proportional integral derivative controller by using direct method. When the time delay exceeds certain critical values, the excitation control system becomes unstable. In order to obtain more delay margin, in control part of the system, fractional order proportional integral derivative controller is used. A formulation is obtained to find out the maximum time delay which is known as delay margin with which the system can tolerate without any loss in its stability. All the possible stability regions analytically in the parametric space of the time delay is obtained by using an exact method and it is presented in this study. The method is formulated in frequency domain. The time-domain simulations are implemented to validate theoretical delay margin results in Matlab/Simulink. When it is compared with previous researches in literature, better stability margin is obtained. The results have shown that fractional order PID controller gives wide stability area than integer order PID controller.

scholarly journals Studies on Advanced 2-axis Excitation Control System for Enhancing Power System Stability

2004 ◽  
Vol 124 (5) ◽  
pp. 697-704
Author(s):  
Suresh Chand Verma ◽  
Shigeaki Ogawa ◽  
Shinya Noguchi ◽  
Masaru Shimomura
Keyword(s):  
Control System ◽  
Power System ◽  
Power System Stability ◽  
System Stability ◽  
Excitation Control

scholarly journals An Accurate Method for Delay Margin Computation for Power System Stability

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3466 ◽  
Author(s):  
Ashraf Khalil ◽  
Ang Swee Peng
Keyword(s):  
Time Delay ◽  
Power Systems ◽  
Power System ◽  
System Stability ◽  
Area Measurement ◽  
Power System Stabilizer ◽  
Iteration Algorithm ◽  
Measurement Units ◽  
System Stabilizer ◽  
Delay Margin

The application of the phasor measurement units and the wide expansion of the wide area measurement units make the time delay inevitable in power systems. The time delay could result in poor system performance or at worst lead to system instability. Therefore, it is important to determine the maximum time delay margin required for the system stability. In this paper, we present a new method for determining the delay margin in the power system. The method is based on the analysis in the s-domain. The transcendental time delay characteristics equation is transformed to a frequency dependent equation. The spectral radius is used to find the frequencies at which the roots cross the imaginary axis. The crossing frequencies are determined through the sweeping test and the binary iteration algorithm. A single machine infinite bus system equipped with automatic voltage regulator and power system stabilizer is chosen as a case study. The delay margin is calculated for different values of the power system stabilizer (PSS) gain, and it is found that increasing the PSS gain decreases the delay margin. The effectiveness of the proposed method has been proved through comparing it with the most recent published methods. The method shows its merit with less conservativeness and fewer computations.

The Motor Active Flexible Suspension and Its Dynamic Effect on the High-Speed Train Bogie

2017 ◽  
Vol 140 (6) ◽  
Author(s):  
Yuan Yao ◽  
Yapeng Yan ◽  
Zhike Hu ◽  
Kang Chen
Keyword(s):  
Control System ◽  
Time Delay ◽  
High Speed ◽  
State Feedback ◽  
State Feedback Control ◽  
System Stability ◽  
High Speed Train ◽  
Suspension Parameters ◽  
Linear And Nonlinear ◽  
Hunting Stability

We put forward the motor active flexible suspension and investigate its dynamic effects on the high-speed train bogie. The linear and nonlinear hunting stability are analyzed using a simplified eight degrees-of-freedom bogie dynamics with partial state feedback control. The active control can improve the function of dynamic vibration absorber of the motor flexible suspension in a wide frequency range, thus increasing the hunting stability of the bogie at high speed. Three different feedback state configurations are compared and the corresponding optimal motor suspension parameters are analyzed with the multi-objective optimal method. In addition, the existence of the time delay in the control system and its impact on the bogie hunting stability are also investigated. The results show that the three control cases can effectively improve the system stability, and the optimal motor suspension parameters in different cases are different. The direct state feedback control can reduce corresponding feed state's vibration amplitude. Suppressing the frame's vibration can significantly improve the running stability of bogie. However, suppressing the motor's displacement and velocity feedback are equivalent to increasing the motor lateral natural vibration frequency and damping, separately. The time delay over 10 ms in control system reduces significantly the system stability. At last, the effect of preset value for getting control gains on the system linear and nonlinear critical speed is studied.

scholarly journals Adaptive Dynamic Surface Control for Generator Excitation Control System

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Zhang Xiu-yu ◽  
Liu Cui-ping ◽  
Wang Jian-guo ◽  
Lin Yan
Keyword(s):  
Neural Network ◽  
Control System ◽  
Tracking Error ◽  
Dynamic Surface Control ◽  
Excitation Control ◽  
Dynamic Surface ◽  
Adaptive Dynamic ◽  
Surface Control ◽  
Control Scheme ◽  
Generator Excitation Control

For the generator excitation control system which is equipped with static var compensator (SVC) and unknown parameters, a novel adaptive dynamic surface control scheme is proposed based on neural network and tracking error transformed function with the following features: (1) the transformation of the excitation generator model to the linear systems is omitted; (2) the prespecified performance of the tracking error can be guaranteed by combining with the tracking error transformed function; (3) the computational burden is greatly reduced by estimating the norm of the weighted vector of neural network instead of the weighted vector itself; therefore, it is more suitable for the real time control; and (4) the explosion of complicity problem inherent in the backstepping control can be eliminated. It is proved that the new scheme can make the system semiglobally uniformly ultimately bounded. Simulation results show the effectiveness of this control scheme.

scholarly journals Stability and Time Delay Tolerance Analysis Approach for Networked Control Systems

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Ashraf F. Khalil ◽  
Jihong Wang
Keyword(s):  
Control System ◽  
Time Delay ◽  
Control Systems ◽  
Networked Control Systems ◽  
Networked Control System ◽  
Networked Control ◽  
Finite Difference Approximation ◽  
System Stability ◽  
Delay Tolerance ◽  
Maximum Time

Networked control system is a research area where the theory is behind practice. Closing the feedback loop through shared network induces time delay and some of the data could be lost. So the network induced time delay and data loss are inevitable in networked control Systems. The time delay may degrade the performance of control systems or even worse lead to system instability. Once the structure of a networked control system is confirmed, it is essential to identify the maximum time delay allowed for maintaining the system stability which, in turn, is also associated with the process of controller design. Some studies reported methods for estimating the maximum time delay allowed for maintaining system stability; however, most of the reported methods are normally overcomplicated for practical applications. A method based on the finite difference approximation is proposed in this paper for estimating the maximum time delay tolerance, which has a simple structure and is easy to apply.

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