L.R. Linares

Real-time EMTP-based transients simulation

A computer program has been written for the simulation of power system transients in real time. The program is based on EMTP models and solution techniques optimized for maximum performance in superscalar computer architectures. Timings ranging from 38 to 107 /spl mu/s have been obtained for systems from 18 to 30 nodes using an IBM RISC System/6000 Model 560 workstation. These timings are considered adequate for real-time testing of protective relaying equipment. The program is compatible with existing EMTP data cases. >

Efficient and accurate representation of asynchronous network structure changing phenomena in digital real time simulators

Due to synchronization requirements related to the interfacing with external systems, digital real time simulators of electromagnetic transients for equipment testing employ a constant integration time step width for solving the network equations. Therefore, the network solution is only calculated at discrete and equidistantly spaced time instants while in reality the time domain is continuous. Changes in network structure that occur between the discrete solution points are generally not simulated exactly. This can lead to switching control mistakes and numerical problems. In this paper the novel clock synchronized structure changing concept, which allows the accurate and efficient simulation of structural changes at arbitrary time instants, is presented.

Efficient HVDC converter model for real time transients simulation

An efficient model has been developed to simulate high voltage direct current (HVDC) power converters in real-time transient simulators. Real time performance of 45 /spl mu/s per solution step has been achieved for a 12-pulse monopolar converter and 81 /spl mu/s for the bipolar converter using a single processor Pentium Pro 200 MHz desktop computer. The HVDC power converter model is solved simultaneously with the power network. Simultaneous solution makes the model capable of sustained long-time simulation for real time testing of system performance and control functions.

Multirate Simulations With Simultaneous-Solution Using Direct Integration Methods in a Partitioned Network Environment

Multirate simulation of electric networks exhibiting a wide variety of time constants decreases the simulation runtimes by exploiting the property of circuit latency. The fundamental idea is to use different integration steps for different network subsystems, according to the requirements of accuracy of each subsystem. Programs that exploit circuit latency are usually based on relaxation methods that require iterations among the different subsystems of the original networks. These methods lack the numerical robustness of direct implicit integration methods used in circuit simulators and are not adequate for real-time simulation due to their non-uniform solution times. This paper proposes circuit latency exploitation without iterations making use of the concept of interlinked Multi-Area Thevenin Equivalents (MATE). Results are presented showing the efficiency and accuracy of the method

Current transformers and coupling-capacitor voltage transformers in real-time simulations

This paper describes two models: a saturable current transformer model ((CT) and a wide-band coupling capacitor voltage transformelr suitable for real-time transients simulation. By using very efficient network reduction and network synthesis techniques, the operations count for these models is kept to a minimum. The accuracy of the models has been tested in connection with our real-time transients simulator RTNS [l] and compared to conventional EMTP models [2]. Kevwords: Current transformers, coupling capacitor voltage transformers, EMT modelling, real-time simulation. secondary current from the known primary current is described here, a) Equivalent circuit A equivalent circuit Of the current transformer is Shown in Fig. 1 with all quantities referred to

A Dynamic Circuit-Based Ferromagnetic Model

The development of a new dynamic circuit-based ferromagnetic model is described. The investigation of the behavior of a 24-gauge M19 silicon steel led to the conclusion that, for this material, a model that has static parameters is unable to accurately reproduce the behavior of the actual material over a large range of input frequencies and excitation levels without resorting to retuning the parameters of the model. This paper proposes two new mechanisms that dynamically adjust the parameters of the model. The provided results clearly show the effectiveness of these mechanisms.