Tsuneo Taniguchi

Sliding mode controller design based on fuzzy inference for nonlinear systems (power systems)

Sliding-mode control can deal with nonlinearities of control systems and is robust. However, it has drawbacks, such as high control gain effect and control chattering. A method of nonlinear feedback control that introduces fuzzy interference into sliding-mode control, to treat nonlinearities and reduce chattering is proposed. The stability of the system is discussed using fuzzy stability theory based on Lyapunovs direct method. The method is applied numerically to the stabilizing control of an electric power system, and is shown to give good results. >

Structural control of electric power networks for transient stability

This paper presents a sensitivity-based approach for structural control of electric power networks using FACTS (flexible AC transmission system) devices in order to improve the transient stability margin for one controlling unstable equilibrium point (u.e.p). It is comprised of the sensitivity analysis of critical energy of the TEF (transient energy function), network control strategy and evaluation. A related practical application to a 39-bus test system follows and shows that the structural control of power networks is effective for the enhancement of power system transient stability. >

Transient stability analysis for power system using Lyapunov function with load characteristics

This paper presents constructing Lyapunov function of power system for estimating transient stability considering with load dynamics characteristics. An induction machine is treated as a representation of dynamic load. In the composition process of the proposed Lyapunov function, the slipping dynamic characteristic of the induction machine is implicitly expressed in the swing equation of power systems. As a result, the dynamic characteristic of an induction machine becomes equivalent to a synchronous machine with a voltage adjustment mechanism to which a dissipation function is added. Using this proposed system description, the Lyapunov function is composed by the state function method, which is based on an expanded energy function. The effectiveness of the proposed Lyapunov function is verified numerically for multimachine power systems with induction machine load.

New approach to the synthesis of a stabilizing control method for a power system

Abstract A new approach to the synthesis of a stabilizing control method for a multimachine power system is presented. The power system dynamics based on the usual assumptions can be formulated as a class of non-linear dynamic systems in which are contained the sinusoidal functions associated with the power torque-angle curve of the AC generator. In this theoretical scheme, an optimal control law, which retains the principal non-linearity of the system, is derived by using optimization techniques well known in linear optimal control theory. The stabilizing control of an N-synchronous machine power system with velocity governor and phase-shifter is synthesized by using the optimal control method. The usefulness of the proposed method is illustrated by the stabilizing control problem for a three-machine power system, taking into account additional control signals for the governing system and phase-shifter control systems, and simulation results are given numerically.

Synthesis of a stabilizing control problem for a multimachine power system with phase shifter

A systematic procedure is considered for the synthesis of a stabilizing control method for a multimachine power system with phase shifter, taking into account the velocity governor. A new approach is presented, which uses a coordinate-transformation technique and an optimization technique. The application of this method to a stabilizing control problem for a power system is illustrated by considering a 3-machine power system with phase-shifter control, taking into account an additional control vector for the governing system with one time constant. The synthesized controls are then used to improve the power-system transient stability to a remarkable degree and to restore the power-system transients rapidly to the stable-equilibrium point. Numerical results arc given.

A method of optimization taking into account the non-linearity of the power torque-angle curve for a synchronous machine

Abstract A systematic procedure is considered for the synthesis of an optimal control law for damping large oscillations associated with transient conditions in power systems. A new approach is presented, which uses the dynamic programming approach of the constant-value control problem. The application of this method to a power-system optimal control problem is illustrated by considering a single machine connected to an infinite bus, taking into account the velocity governor, which is represented by a first-order response. The synthesized controls are then used to damp large oscillations associated with transient conditions. Furthermore, the system responses given by these controls are compared with those obtained by the conventional control, and numerical results are shown.

Structural control based on genetic algorithm and neural network for electric power systems

This paper presents a method of structural control of electric power networks for improving their stability. The method is based on the FACTS concept, a genetic algorithm and neural network. FACTS equipment will provide some new ways for improving stability by controlling the reactance of transmission lines in terms of structure control of the power network. A case study with a multimachine power system is presented and discussed.<<ETX>>

A Lyapunov function for power system including induction machine dynamic characteristics

This paper presents a Lyapunov function for power system considering with dynamics of induction machine characteristic by the state function method. The Lyapunov function for power system with induction machine is hoped for being settled for a long time. In the composition process of proposed Lyapunov function, the slipping dynamic characteristic of the induction machine is implicitly expressed. As a result, the dynamic characteristic of induction machine becomes equivalent to a synchronous machine with the voltage adjustment mechanism. The Lyapunov function is composed under the condition of some approximations.

Fuzzy optimal controller design based on neural network for nonlinear systems

A method of constructing a fuzzy optimal controller for nonlinear systems is proposed. The method is based on a fuzzy model and is intended to give optimal control using neural networks. In this method, a cost function is introduced in the neural network, and unsupervised learning is performed. The method is applied numerically to the stabilizing control of a one-machine infinite-bus electric power system.<<ETX>>

Modelling of Dynamic Load Including Inverter Apparatuses in Electric Power Systems

近年,電 圧不安定現象 が注 目を集 めてお り,動 的 負 荷特性 がその大 きな要 因の一つ とされてい る。一方, インバ ータエ アコンti)をはじめイ ンバ ータ応 用負荷 は 急速 に普及 してお り,そ の影響 は無視 で きな い。本 報 告 は,系 統 の小擾乱時 のデー タに基 づ き,イ ンバ ータ 応用負荷 を含 む動的 負荷 を準ニ ュー トン法(2)によ り誘 導電動 機 と定 イン ピーダ ンス負荷か らな る負荷 モデル に縮約 す ることを提 案 し,こ の モデルが系統 の大擾 乱 時 において も有効 であ ることを示 す もので ある(3)。 例題 系統 としては,図1の よ うな3母 線系統 を取扱 う(4)。母線3 に接続 され る負荷 は定 イ ンピー ダンス負 荷(YL3),イ ンバー タ応用 負荷(IA)お よび5種 類 の 誘 導 電 動 機(A~E)と す る。そ の 出 力 比 はA~C がそれ ぞれ10%, D, Eは それぞれ15%と し, IAの 出力比 が10,20,30%の 場 合 につ い て検 討 を行 う。 ただ し,そ れ ぞれの誘 導電 動機 は 内部誘 起電 圧 左 と 滑 りsに よる三次 の動特性式 で表現す る。