Transient study of two 500 kV coupled lines in a transient network analyzer

Electromagnetic transients are the tidal waves of electric power systems. These momentary voltage surges generally lasting only fractions of a second can be powerful enough to disrupt normal operations and even cause serious damage to major pieces of equipment, such as transformers. Created by lightning, line faults, substation switching functions, and other sudden events along a utility network, transients must be taken into account both in choosing equipment ratings for a power system and in setting its operating parameters. Like the builders of a seawall that must withstand the highest expected waves from the ocean, engineers trying to guard against damage from transients face an extraordinary design task. Most of the huge computer simulation codes related to power systems either model steady-state conditions or deal with system stability problems. The analysis of electromagnetic transients, on the other hand, requires a much more detailed examination of how some critical portion of a power system will react to conditions that can change greatly in microseconds. For many years, simulation of transient effects was performed by special-purpose analog computers called transient network analyzers (TNAs). These machines, which are still in use, recreate a portion of the power system in miniature, complete with voltage sources representing generators and various kinds of capacitive or inductive loads. TNAs are generally adequate but relatively inflexible, tedious to set up, and cumbersome to use. Once a system configuration is modeled, many simulations can be performed. Given the need to manually reconfigure TNA circuits to represent changes in a system, however, the analyzers can also be quite expensive to use. During the late 1960s, Herman Dommel of the Bonneville

Overall critical evaluation of the dynamics of EHV dc-power transmission requires that a variety of system conditions and effects of many parameters be studied. Problems can be strictly electrical or electromechanical. In general, those that fall in the former category are of short time duration, while those in the latter may be either of intermediate duration, on the order of 1 second, or of long duration, from 2 to 40 seconds. The approach used, whether it be 1) a physical model such as a transient network analyzer; 2) an analog computer, sometimes called an electronic differential analyzer, or 3) a digital computer, will depend upon the specific problem at hand. The capabilities and limitations of the analog computer in providing solutions to electromechanical problems are outlined in this paper, and the results reported give insight into the dynamic performance characteristics of a dc link under constant current or power control, with or without a parallel ac line.

A cryogenic power cable is expected to be capable of carrying bulk power as a main transmission line in a future metropolitan electric power system. It is important to establish a strategy of how to sustain power supply when such a highly densified power supply route trips from the network due to contingency. It is proposed here that the bulk power transmitted by the cryogenic cable could be distributed into the parallel conventional transmission lines by suitable circuit breaker operations in the system. In this process, power‐flow routes are forced to be changed with a remarkable modification in the system configuration. In this paper, the power swings associated with the large power‐flow change following contingent faults are analyzed by means of a transient network analyzer. It is found that the proposed system modification could be realized without any harmful power swing if the parameters in generators as well as in control devices have conventional magnitudes. It is shown also by simulations that the margin to occurrence in an unstable power swing is left sufficient even if the parameters deviate somewhat from the present magnitudes.

An electronic arc model has been developed which simplifies the study of harmonic phenomena in are furnace power systems on a transient network analyzer (TNA). The model helps insure the proper magnitude and phase relationship of the harmonies at each loading condition. The simulation procedures and arc model characteristics are described. Also, some examples of typical study results are given.

As an industrial customer of the utility, electrical arc furnace (EAF) is the major flicker source that degrades the grid power quality. As a possible solution, STATCOMs with high bandwidth can be used. In this paper, the normalized model of a CMC-based STATCOM and an EAF model are introduced, and then a DQ-model based control strategy is proposed for flicker mitigation. Case studies are conducted for STATCOM applying to a 40 MVA EAF arc furnace. Simulation results verify the controllers' stability and performance. A transient network analyzer (TNA) is developed to experimentally test the developed controller.

A comprehensive state-space model of two-stage grid-connected PV systems in transient network analysis

A static VAr compensator (SVC) was installed at the Eddy County substation near Artesia, New Mexico. It was put into commercial operation in April 1992. Before the commissioning period, a phase of extensive testing and analysis of the digital closed loop control was undertaken. This work was done using the actual control hardware and software in conjunction with an analog TNA and with digital simulation models of control and power systems. Results of this work were checked with the power system during field commissioning of the SVC. This paper gives an overview of the closed loop control design. It presents some results from the TNA tests, digital simulation and commissioning field tests of the SVC operation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Steady-state overvoltages can occur on EHV transmission systems during various system operating conditions. The voltage waveforms are characterized by a periodic waveform which may be distorted by harmonics if iron saturation of equipment on the lines occurs. This paper discusses the results of digital and transient network analyzer (Anacom) studies which analyzed system parameters with respect to their effect on harmonics in steady-state overvoltages. Special emphasis was focused on the factors influencing harmonic distortion of the steady-state voltages.

Energy storage systems (ESSs) are considered an 'enabling' infrastructure technology that can provide ride-through electricity during outages, enhance power quality, and improve utility reliability. Transmission ultracapacitor (TUCAP), integrating modular voltage source converters (VSCs) with ultracapacitor (UCAP) energy storage unit, are state-of-the-art power electronics-based EESs for utility high power application. In this paper, modeling and design of a TUCAP is presented. Firstly, the testing results of UCAP are described. The model and parameters of UCAP are extracted from the experimental results of both low-voltage cell and high-voltage string. Secondly, a cascade multilevel converter (CMC) utilizing modular VSCs is proposed for TUCAP's Power Conditioning System (PCS). The potential issues of UCAP for high power operation are discussed. The interface and control technology of a TUCAP combining CMC and UCAP are presented. And the simulation results are given for controller verification. Finally, the experimental results on a scaled-down transient network analyzer (TNA) system are given and validate the model and design of the TUCAP system.

The results of Transient Network Analyzer (TNA) studies evaluating the feasibility of low-side switching long transformer terminated lines is reported. It is shown that overvoltages following line dropping and fault clearing can severely stress surge arresters and circuit brtakers exceeding capabilities specified in ANSI standards. These overvoltages are often not carefully considered in design studies, since the available literature on low-side switching of EHV transmission lines primarily deals with energizing the line and transformer.1,2,3,4

Article Free Access Share on D-C and transient analysis of networks using a digital computer Author: F. H. Branin Development Laboratory, Data Systems Division, International Business Machines Corporation, Poughkeepsie, New York Development Laboratory, Data Systems Division, International Business Machines Corporation, Poughkeepsie, New YorkView Profile Authors Info & Claims 25 years of DAC: Papers on Twenty-five years of electronic design automationJune 1988 Pages 285–305https://doi.org/10.1145/62882.62916Published:01 June 1988Publication History 4citation184DownloadsMetricsTotal Citations4Total Downloads184Last 12 Months14Last 6 weeks2 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

PEEC model of DC bus is an accurate and effective way to analyze the transient process and EMI characteristic of converters. However, the PEEC model with normal partition method is very complicated. It is necessary to construct a brief and legible model. This paper proposes the partition rules and constructs the simple model of the DC bus in an H-bridge unit. Transient process analysis and two-port network analysis proved the simple model provides reasonable accuracy.

Unlike stationary behavior, time-dependent blocking probabilities for loss networks are not well understood and little work has been done except for the single service center case. We propose novel closed-form transient analysis methods for single Erlang loss system and networks, to the best of our knowledge, these are the most efficient ways to analyze the transient behavior of Erlang loss system and networks. Applying this model, time-dependent provisioning can satisfy dynamically changed traffic demands and avoid overprovisioning problem in connection-oriented loss networks.

We present a new method for the efficient estimation of rare events and smart probabilities in Markovian queueing networks. The method uses importance sampling to modify the probability distribution of the events to be observed. In contrast to most other importance sampling approaches, transient instead of steady state analysis is considered and the change of the measure is computed adaptively. The whole approach is based on the combination of discrete event simulation and randomization, a technique to transform a continuous time Markov chain into a discrete time chain and an associated Poisson process. By means of randomization it is possible to derive a simple model describing me relation between me occurrence of the rare event and the probability of different transition types. This model can be used to compute adaptively the change of transition probabilities to make the rare event less rare depending on the observed behavior in some replications and the time horizon of transient analysis. If the time horizon increases, the method is extended by introducing regeneration points in the analysis. By means of small examples it is shown that the method yields satisfactory results even for more complex queueing networks for which optimal or approximatively optimal importance sampling parameters are not known from the theory.

This paper proposes a novel method for analyzing large on-chip power delivery networks via a stochastic moment matching (SMM) method. The proposed method extends the existing direct stochastic random walk method that can be only applied to DC analysis in purely resistive networks or transient analysis of RC networks with low efficiency. The new method can analyze general structure RLC networks by combining the stochastic process with frequency domain moment matching technique. As a result, we achieve better scalability than traditional frequency domain P/G analysis approaches, and better efficiency than the existing random walk transient analysis techniques. Our experimental results show that SMM can easily trade efficiency for accuracy or vise versa. SMM can easily deliver 10/spl times/-100/spl times/ speedup over a LU-based direct solver and about 10/spl times/ speedup over the pure random walk method with reasonable accuracy on large industry P/G networks.