Mehmet Salih Mamiş

Solution of eigenproblems for state-space transient analysis of transmission lines

Abstract When lumped parameter models are used for transmission lines, which are originally distributed parameter systems, the set of first order ordinary differential equations (ODEs) of the lumped parameter equivalent circuit can be arranged so that the coefficient matrix is in the tridiagonal form. In the circuit theory, these equations are called as state-equations and in the analytical solution of these equations computation of matrix exponential takes an important part. One way to calculate the matrix exponentials and other matrix functions is to use similarity transformations, which requires eigenanalysis of the coefficient matrix. In this study, state-space technique for computation of transmission line transients is given. Calculation of matrix exponentials for coefficient matrices having tridiagonal structures and eigenproblems associated with it are investigated. QR algorithm, LR algorithm and characteristic equation method for eigenvalue calculation are treated for this type of matrices in both accuracy and computer run time point of views. Several cases are considered and effect of matrix dimension and ill-conditions are also examined.

Remark on the Lumped Parameter Modeling of Transmission Lines

Transmission lines are distributed parameter systems. Instead of distributed parameter models, lumped parameter models are also used for steady-state and transient analysis of transmission lines. Lumped parameter modeling for transmission lines is obviously an approximation. This paper aims to investigate the theoretical error in the lumped parameter modeling of transmission lines for steady-state and transient analysis. To determine the error, steady-state and transient responses of the transmission line are calculated by using both distributed and lumped parameter modeling. The effect of number of sections used for lumped parameter modeling is investigated. Obtained results can be used for the determination of the number of sections.Transmission lines are distributed parameter systems. Instead of distributed parameter models, lumped parameter models are also used for steady-state and transient analysis of transmission lines. Lumped parameter modeling for transmission lines is obviously an approximation. This paper aims to investigate the theoretical error in the lumped parameter modeling of transmission lines for steady-state and transient analysis. To determine the error, steady-state and transient responses of the transmission line are calculated by using both distributed and lumped parameter modeling. The effect of number of sections used for lumped parameter modeling is investigated. Obtained results can be used for the determination of the number of sections.

Transient analysis of nonuniform lossy transmission lines with frequency dependent parameters

Abstract An s-domain method for transient analysis of lossy, frequency dependent nonuniform transmission lines having parameters arbitrary varying with space is presented. Nonuniform line is divided into adequate number of sections which are then assumed uniform. The terminal equation for the nonuniform line is calculated by using the terminal equations of the uniform line sections. By using the boundary conditions, total response in s-domain is obtained. Fast inverse Laplace transform is used for frequency to time domain conversion. In one of the examples, the step response of an open ended nonuniform line is obtained and the results are compared with those obtained by lattice-diagram technique. The effect of number of sections is investigated and it is concluded that for sufficiently large number of sections, the results approach to the analytical solutions which can be obtained only for very special nonuniform lines. In the second example, the method is applied for the calculation of transmission tower lightning surge response.

Price-Efficiency Relationship for Photovoltaic Systems on a Global Basis

Solar energy is the most abundant, useful, efficient, and environmentally friendly source of renewable energy. In addition, in recent years, the capacity of photovoltaic electricity generation systems has increased exponentially throughout the world given an increase in the economic viability and reliability of photovoltaic systems. Moreover, many studies state that photovoltaic power systems will play a key role in electricity generation in the future. When first produced, photovoltaic systems had short lifetimes. Currently, through development, the technology lifecycle of photovoltaic systems has increased to 20–25 years. Studies showed that photovoltaic systems would be broadly used in the future, a conclusion reached by considering the rapidly decreasing cost of photovoltaic systems. Because price analysis is very important for energy marketing, in this study, a review of the cost potential factors on photovoltaic panels is realized and the expected cost potential of photovoltaic systems is examined considering numerous studies.

Discrete-Time State-Space Modeling of Distributed Parameter Transmission Line

This work presents a new approach for state-space modeling of distributed parameter transmission line for transient analysis. The lossless line model based on the method of characteristics is used and the state equations are derived. These equations are converted to a set of difference equations using the trapezoidal rule of integration. By solving these equations, the state of system at discrete time points is obtained. An illustrative example is given and the obtained results are compared with those obtained using conventional methods based on s-domain and fast inverse Laplace transform (FILT). The study also investigates the effects caused by lumped parameter approximation of line losses.

Harmonic analysis in power systems with Discrete Fourier Transform

Harmonics has become more significant issue due to the increasing of utilization of the non-linear loads and switching elements such as inverter on the power system recently. Harmonics disrupts the shape of the current and voltage signals in power systems and leads to many problems in power systems. It has made harmonic analysis necessary on the power system. Harmonics has become more significant issue due to the increasing of utilization of the non-linear loads and switching elements such as inverter on the power system recently. In this study a method is designed to obtain a basic signal by using Discrete Fourier Transform (DFT) in order to determine harmonics on power systems. The simulation of this method has been implemented by using Matlab/Simulink software package.

Utilization of energy from waste plants for microgrids

Energy from Waste (EfW) should be taken account as an alternative renewable resource for local energy generation in microgrids. This study theoretically demonstrates benefits of EfW plants for microgrids. Power flow simulation results were shown for a scenario of town grid with the population size of 115000. IEEE 9 Bus system is used to model distribution system of this town. 5 MW Energy from Waste Incineration (EfWI) plant and 10 MW solar plant are integrated to distribution system. Simulation results demonstrate that despite the fact that EfWI plant provides a limited energy generation potential, it can be utilized as a secondary renewable source to reduce peak demand in the hours of excessive demand.

Fault location on series compensated power transmission lines using transient spectrum

Nowadays sustainability and quality of energy have gained more importance. Power outages due to failures particularly cause interruption of production at industrial facilities may lead to loss of manpower and resources. One of the major causes of power outages in the power system is the short-circuit faults occurring in transmission lines. The most important requirement to clear the fault in a short time is to estimate the fault location quickly and accurately. In this study, fault location is determined in series compensated power transmission lines utilizing transient frequency spectrum. It has been shown that the method is suitable for series compensated lines.

Detecting fault type and fault location in power transmission lines by extreme learning machines

Importance of supplying qualified and undisturbed electricity is increasing day by day. Therefore, detecting fault, fault type and fault location is a major issue in power transmission system in order to prevent power delivery system security. In previous studies, we observed that faults can be easily determined by extreme learning machine (ELM) and the aim of this study is to determine applicability of ELM in fault type, zone and location detection. 8 different feature sets were exacted from fault data that produced by ATP and these features were assessed by 15 different classifier and 5 different regression method. The results showed that ELM can be employed for detecting fault types and locations successfully.

Non-iterative Nodal Approach for Transient Simulation of Nonlinear Elements

A non-iterative nodal solution method for transient simulation of nonlinear elements is presented Terminal equations of inductors and capacitors are transformed into algebraic equations using the trapezoidal rule of integration. Nodal equations are formulated as a set of algebraic equations by treating all nonlinear elements as linear and LU factorization is used for the solution of these equations at each time step. A nonlinear variation of the system elements is represented by renewing the nodal conductance matrix at each time step of the solution. Several examples with various circuit configurations and different nonlinear characteristics are considered, and comparisons with available methods are included. As the solution method is not iterative, convergence and initialization problems are avoided. Formulation and solution steps are simple and the method can be easily implemented in the nodal solution-based circuit simulators such as SPICE and EMTP.