This paper presents a method for determining optimal arrangements of parallel independent overhead power lines aimed to decrease electric and magnetic field emissions. The Genetic Algorithm (GA) is used to find the optimal placement of conductors. The Monte Carlo approach implemented in GA allows consideration of uncertain phase shifts between independent overhead power lines. The results and practical aspects of the proposed methodology are illustrated on two different configurations of both independent 400 kV singlecircuit and double-circuit overhead power lines.

This study proposes a new algorithm for power harmonics parameters estimation based on the modified Newton-Raphson method. The main modification is achieved through reconfiguration of the Jacobian matrix and direct calculation of its characteristic coefficients without the necessity of inversion. The zero-crossing method was used to compute the frequency basically for initial frequency estimation. With additional digital filtering, the parameters can be initialised properly and the updating steps can be supervised for fast quadratic convergence of Newton-Raphson iterations. This combined approach yields high accuracy and good tracking speed, thereby significantly facilitating both the computation and programming. Reliability and effectiveness of the proposed method were confirmed through simulation tests and results. 2 Proposed algorithm Assume that the input signal of the fundamental frequency f is band limited to the first M harmonic components. This form of continuous signal with a complex harmonic content can be represented as a sum of the Fourier components as follows:

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The paper proposes new algorithm for estimation of the fundamental phasor in a power system, based on removal of exponentially decaying DC components (DDCs). These components, as well as high-order harmonics and noise components, have a considerable effect on accuracy and speed of convergence in numerical and digital relays – speed of the protection relay operation. A Discrete Fourier Transform (DFT) based approach with modified Prony method was used to calculate and remove the unwanted effect of DDCs in a time interval slightly longer than the period of the fundamental harmonics. The proposed procedure offers the possibility to estimate the parameters of unwanted DDCs in a simpler and analytically more precise way, thus facilitating its program implementation. The algorithm offers the ability to easily adjust the response speed - detection time. This flexibility of the algorithm provides a compromise in terms of response speed as well as expected reliability and security of fault detection. The developed procedure enables the monitoring of the very demanding dynamics of the current signal in short-circuit conditions, and thus the estimation of the phasor parameters of the energy signal so that the relay protection is able to respond to this emergency situation in the most adequate (adaptive) way - it becomes more precise and faster in its response. The algorithm has low numerical and computational complexity, while maintaining its high performances even in conditions of a very strong noise signal. The simulation results for different test signals demonstrate high precision in the estimation of fundamental phasor of the proposed algorithm.