Online thevenin equivalent parameter estimation using nonlinear and linear recursive least square algorithm

Abstract

Abstract-This paper proposes method for detection, estimation of Thevenin equivalent parameters to describe power system behavior. Thevenin equivalent estimation is a challenge due to variation in system states caused by power flow in the network. Thevenin equivalent calculation based on changes in system with multiple sources integrated with grid, isolated distributed generator system is analysed and nonlinear least square fit estimation technique for algorithm is adopted. Linear least square fit is used with a linearized model. Performance evaluation of proposed method is carried out through mathematical model, nonlinear and linear least square fit based algorithm technique and simulation through MATLAB/SIMULINK package. Accurate grid and source side impedance estimation technique is applicable for distributed generation sources interfaced with grid to improve dynamic response, stability, reliability when subjected to faults or any other disturbances in network. Algorithm can accurately estimate Thevenin equivalent of multiple sources connected in parallel simultaneously with voltage and current phasor measurements at point of common coupling. Mathematical analysis and simulation results validate the effectiveness of proposed method.

Study on conducted EMI noise source modelling applied in electromagnetic compatibility analysis based on GA in cooperation with LM

“…where f is the independent variable, Z X and ψ are the dependent variable R, L and C signify the undetermined parameters, φ 1 and φ 2 are non-linear functions of undetermined parameters. The parameter estimation of function (17) is to determine the values of the RLC parameters by the measured data sequence {(f; Z x , ψ)}.…”

“…In previous studies, intelligent algorithms were rarely applied in the optimisation of data, which obtained by traditional extraction methods. However, in many other fields such as biology, environment and electrical engineering, these intelligent algorithms have been used widely [17][18][19][20][21][22][23][24][25]. To improve the defect of the traditional extraction methods, scattering parameters (SPs) in cooperation with genetic algorithm (SP-GA) method has been proposed to obtain the equivalent RCL parameters of the impedance in the previous work [26].…”

Investigation on conducted EMI noise source impedance extraction for electro magnetic compatibility based on SP‐GA algorithm

“…The values of {u j } can be substituted into the initial parent-unit value x j . The optimisation variable can be solved based on (8), and the target function value can be solved based on (9). Moreover, in the paper, the number c of random value groups can be set to 3.…”

“…The traditional methods have extracted the noise source impedance to a certain extent, but there are still many defects that need further improvement. In the current research, intelligent algorithms have not been used to optimise the data extracted by the traditional methods, and these intelligent algorithms have been applied in many research such as biology, medical, chemistry, environment, and electrical engineering [9][10][11][12][13][14][15][16][17].…”