Mini Review Volume 3 Issue 4 - August 2018 DOI: 10.19080/RAEJ.2018.03.555617 Robot Autom Eng J Copyright © All rights are reserved by Adil Brouri Nonlinear Systems Estimation in Renewable Energies Adil Brouri*, Laila Kadi and Tarik Rabyi Moulay Ismail University, Morocco Submission: June 19, 2018; Published: August 02, 2018 *Corresponding author: Adil Brouri, Moulay Ismail University, Morocco, Email: Robot Autom Eng J 3(4): RAEJ.MS.ID.5555617 (2018) 00100 Abstract In this paper, an approach estimation of nonlinear systems in renewable energies is studied. The system can be structured by blocks- oriented. The proposed solution is more general and can be easy to implement. Keywords: Nonlinear systems; Renewable energies; Oriented blocks; Harmonics analysis Introduction In this work, nonlinear system used in renewable energies is dealt. These nonlinear systems can be described by blocks- oriented. Lately, these types of models are increasingly used practically [1-4]. Nonlinear systems estimation parameters are a necessary step in control [5-7]. The nonlinear element can be in input of system (Figure 1) or in output of system (Figure 2). If the two blocks are parametric, the determination of parameters nonlinear system can be done using quite a few solutions e.g. [1- 4]. When both parts are parametric, the identification problem has been dealt with using several methods e.g. [1,8-10]. Two- stage nonlinear parameters estimation solutions, involving two stages, have been established in e.g. [1,8-10]. Presently, a solution nonlinear parameters estimation is dealt. The considered nonlinear system has a nonlinear element in output of system (Figure 2). Figure 1: Hammerstein nonlinear systems. Figure 2: Wiener nonlinear systems. These nonlinear models can describe several industrial systems [11]. These models have been much more useful to represent nonlinear systems. In this paper, an estimation approach is developed to determine the nonlinear and linear elements parameters (i.e. G(s) and f(.)). The paper is organized as follows: a brief description of the considered nonlinear system is presented in Section 2; the nonlinear system parameters (of nonlinear and linear elements) determination is formulated in Section 3; This paper will be concluded by a conclusion in Section 4. Presently, the proposed nonlinear models consist of a linear element followed in series by a nonlinear function (.) h (Figure 1). This nonlinear system is analytically defined by the following equations: () ( )* ( ) wt gt vt = …………………………. (1) ( ) () () xt hwt = ……………………………. (2) ( ) () () () yt hwt t ξ = + ………………….. (3) Note that the difficulty of this problem comes from the fact that, only the input of nonlinear system v(t) and the output signal y(t) are measurable. The equation error ξ(t) is a stochastic sequence of independent random variables. This signal describes the external noise. The linear dynamic block is characterized by the amplitude ( ) Gjω and the phase ( ) ϕω . The system n onlinearity h(.) is parametric, e.g. polynomial function of order p. The output of nonlinear block can be expressed as: ( ) 0 () () () p k k k xt hwt wt λ = = = ∑ ………………. (4)