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Overvoltages on Power Systems
Published in Mazen Abdel-Salam, Hussein Anis, Ahdab El-Morshedy, Roshdy Radwan, High-Voltage Engineering, 2018
The Electromagnetic Transients Program (EMTP) is a computer program for simulating electromagnetic, electromechanical, and control system transients on electric power systems (EMTP Development Coordination Group, 1996). The EMTP is used to solve the ordinary differential and/or algebraic equations associated with an “arbitrary” interconnection of different electrical (power system) and control system components. The implicit trapezoidal rule of integration is used in the discretization of the equations of most elements which are modeled by ordinary differential equations. The result is a set of real, simultaneous, algebraic equations which is solved at each time-step using advanced sparsity techniques. These equations are written in nodal-admittance form (with new unknown voltages as variables), and are solved by ordered triangular factorization. Initial conditions for differential equations of the various components can, for most cases of practical interest, be determined automatically by the program. The calculation of initial conditions is normally limited to linear elements. Nonlinear resistances are always ignored during the steady-state solution. Nonlinear reactances can either be linearized during steady state or fully modeled to include harmonic distortion effects. Injections of the electric network may also be specified in terms of power and voltage magnitude, thereby providing multiphase load flow capability.
E
Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
empirical model mathematical model based on curve-fitting specific mathematical functions to measured data, rather than on device physics. Empirical models generally have a low to midrange modeling valuation coefficient. EMTP the Electro-Magnetic Transient Program, a computer program which simulates an electric power system such that its response to disturbances may be accurately predicted. emulate executing a program compiled to one instruction set on a microprocessor that uses an incompatible instruction set, by translating the incompatible instructions while the program is running. emulation a model that accepts the same inputs and produces the same outputs as a given system. To imitate one system with another. Contrast with simulation.
Series-Compensated Line Protection Philosophies
Published in Walter A. Elmore, Pilot Protective Relaying, 2018
The electromagnetic transients program (EMTP) adds to this important test facility, the ability to model a far more extensive system, to do so with uniformly distributed parameters if desired, to totally define the waveforms, and to eliminate undesired component effects. Provision for both types of tests must be incorporated in a manufacturer’s developmental facility. Each has its strengths and weaknesses.
An Improved Harmonic Load Flow Formulation
Published in Electric Power Components and Systems, 2019
Asim Rashid, Juan José Mesas, Luis Sainz
In the last years, the increasing number of nonlinear loads (NLLs) connected to electric power systems has led to increased harmonic distortion in network voltages and currents. For this reason, the steady state harmonic problem has been extensively studied to determine electric power system harmonic distortion [1]. Procedures for analyzing this problem can be divided into time [2] and frequency domain [3–11] procedures. The former, such as Electromagnetic Transients Program (EMTP), are based on the numerical resolution of electric power system differential equations. They treat NLL equations directly, but require a high calculation effort to obtain steady state solutions and difficult management of power consumption loads. The latter, known as harmonic load flow (HLF) formulations, are reformulations of fundamental load flow (FLF) which consider harmonic bus voltages and NLL state variables as additional unknowns to the fundamental bus voltages. Their main drawback is that NLL equations must be adapted to the frequency domain formulation. These frequency domain procedures pose nonlinear equation systems which must be numerically solved to directly obtain the fundamental and harmonic bus voltages of the network and the variables characterizing the NLL state. There are also hybrid procedures which work in both domains by using their respective advantages [12, 13]. The procedures in the frequency domain are the most widely used in the literature, and Newton-Raphson is the most commonly employed numerical method to solve their nonlinear equation systems. Nevertheless, the numerical resolution of these equation systems has several difficulties such as long execution time, convergence problems and large computer memory requirements due to the significant number of involved unknowns [14, 15].
Initialization of Electromagnetic Transient Simulation Using Differential Quadrature Method
Published in IETE Technical Review, 2021
Fangzong Wang, Haowen Yan, Guoyang Wu, Jie Hao
The electromagnetic transient simulation and related programs (the EMTP-type programs) are widely used in the electromagnetic transient studies of power systems. The transient behavior of the power system can be represented mathematically by ordinary differential equations in the continuous time-domain. Using numerical integration methods such as the implicit trapezoidal rule to solve the ordinary differential equations, the transient response can be calculated in the discrete time-domain.