Real time implementation of H∞ loop shaping robust PSS for multimachine power system using dSPACE

This paper presents the simulation and the experimental validation of the designed robust power system stabilizer (RPSS) to stabilize a linearized uncertain power system using Glover-McFarlane’s H_∞ loop shaping design procedure. Guidance for setting the feedback configuration for loop shaping, weighing functions selection and synthesis are also presented. The efficiency of the designed controller is simulated using Matlab/Simulink and tested by implementing on real time environment using dSPACE work stations DS1005 and DS1104. The real time experimental results of RPSS are compared with that of the conventional power system stabilizer (CPSS) for a three phase fault. Also, the real time simulation results of RPSS are compared with the off-line simulation results of RPSS, thus validating the simulation results with the experimental results. Justification of robustness is also presented by considering three different operating points. The proposed method presented in this paper shows the effectiveness of the RPSS in damping the power system oscillations.     

Robust controller design for large interconnected power systems with model uncertainties based on wide-area measurement

Recently the controller using wide-area measurement systems (WAMS) signals has been suggested to accommodate the dynamic performances of large interconnected power systems. However, there is an unavoidable delay before the wide-area signals are received at the controller site. Therefore, a delay-independent robust control problem of large interconnected power systems is studied via H _∞ fuzzy control method based on wide-area measurement. First, a set of equivalent Takagi–Sugeno (T–S) fuzzy model is adopted to represent the nonlinear large interconnected power system. A wide-area state feedback decentralized H _∞ fuzzy control scheme is developed to override the various disturbances, solve the effect of model uncertainties and stabilize the large power system. The H _∞ decentralized control problem is parameterized in terms of a linear matrix inequality (LMI) problem, and the LMI problem can be solved efficiently using convex optimization techniques. Finally, the effectiveness of the proposed controller design methodology is demonstrated through simulation example. This work is supported by the National Science Foundation of China under grant 60374039, 60404007.     

Decentralized guaranteed cost control for uncertain large‐scale systems using additive control gain

This paper investigates an application of additive control gain to the guaranteed cost control (GCC) problem of decentralized robust control for a class of discrete‐time uncertain large‐scale systems. Based on the Linear Matrix Inequality (LMI) design approach, a class of decentralized local fixed state feedback controllers with additive control gain is established. The novel contribution of this paper is that multiobjective control is attained by using the additive control gain. Although the additive control gain is included in the uncertain large‐scale systems, the closed‐loop system is asymptotically stable. In order to demonstrate the efficiency of our proposed controller, using the fuzzy logic control as the additive control gain, the simple numerical example is given. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(3): 18–32, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20726     

Robust control of doubly fed induction generator for stand-alone applications

The doubly fed induction generator (DFIG) is generally used in the production of the electric energy and more specifically in wind turbines. Currently, a problem of electrical machine control and especially for wind turbines is the change of internal parameters of the machine, which greatly deteriorates the control. In addition, for stand-alone applications, the load and wind speed change frequently. In this paper, a robust control strategy based on the H_∞ control theory is developed for the independent control of the stator voltage amplitude and frequency of a stand-alone DFIG. The DFIG is fed through the rotor windings by a voltage inverter controlled by Space Vector Modulation (SVM). A capacitive and inductive filter is introduced to reduce harmonics on stator voltages and rotor currents. The robust control strategy rejects all the disturbances that may affect the system and that result from the variations of machine parameters, of the rotor speed and of the load. Experimental tests are carried out to verify the effectiveness of the robust control through a comparison with the classical PI regulator in the framework of the Field Oriented Control (FOC) strategy of the DFIG.     

Stochastic H∞ control problem with state‐dependent noise for weakly coupled large‐scale systems

In this paper, stochastic H_∞ state feedback control with state‐dependent noise for weakly coupled large‐scale systems is discussed. After establishing the asymptotic structure of the stochastic algebraic Riccati equation (SARE), a new iterative algorithm that combines the Newton's method with the fixed‐point algorithm is derived for the first time. As a result, both the quadratic convergence and the reduced‐order computation in the same dimension of the subsystems are attained. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.