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A Real Time Digital Transient Network Analyser for testing Equipment on a General Purpose Computer
Abstract
First Page of the Article
... In some particular situations, usually equipment testing, it may be mandatory to have the simulation executed in real time so that the interaction with real equipments can be studied. Recent developments on processors and on parallel computing technology have made possible the development of high-performance digital real-time power systems simulators (DRTPSS) [3] [5] [7] [9] [12]. ...
... Generally, the simulation of some critical phenomena involved in these equipments requires a time step of at least 50 µs in order to achieve acceptable accuracy. Based on this constraint Jerosolomski et al. [3] has estimated the following performance requirements for a typical DRTPSS. ...
... (2) ii) Communication time between two cards. (3) The total communication time is t1 + t2 = 3.2 µs, and, therefore, the simulator would be able to achieve the 50 µs goal. ...
This paper presents the concepts and work in progress concerning the development of a digital real-time power system simulator (DRTPSS). This work follows a different approach that exploits the advantages and low cost of the new standards recently developed for the personal computer market in order to develop a multiprocessor architecture which would be much cheaper than the classical solutions, but still speedy enough to achieve the computing power required to simulate small-and medium-size power networks in real time.
... In result of the great improvements in computer science and technology, digital simulation of electromagnetic transients has increased its domain of application. Recently this domain has been extended to the testing of electrical equipment such as protection relays [1,2]. If this type of tests is to be done in closed loop, then the digital simulation should be performed in real-time. ...
This paper presents a real-time transmission line model with frequency-dependent parameters developed and implemented in the digital transient network analyser ARENE, developed at EDF. The line model is derived by recursive convolution in modal domain, and real frequency-constant transformation matrices are considered. To obtain the frequency-domain rational approximation of the propagation function and characteristic admittance, an accurate model of reduced order is achieved by using an optimal fitting algorithm. The efficiency of the model is evaluated both by speed and accuracy criteria, comparisons being made with EMTP simulation using the frequency-dependent J. Marti model. In the test case presented a 37-µs computation time was achieved for a three-phase untransposed transmission line.
Power systems rely more and more on a wide range of equipment that regulate power plants, voltage and reactive power, or protect the grid against malfunctions.
This paper details the development of a controllable analog emulator for power system analysis. The emulator consists of reconfigurable analog hardware for power system emulation and a digital computer, along with associated software, for configuration, control, calibration and data acquisition. The analog hardware is fully controllable via the software interface. System parameters, initial conditions, integration, faults and contingencies can be created or altered via the software with no changes or manual intervention to the analog hardware. This advance overcomes one of the larger drawbacks of older analog computers, which was the need for manual configuration and calibration. The emulation methodology is presented in this paper as well as power system modeling, both theoretical and in analog hardware. The software interface and control is also presented. To validate the operation of the emulator two examples are shown from a prototype emulator. The first being a steady state power flow solution, the second computes the critical clearing time of a generator fault for transient stability.
This paper presents the design of new real time digital simulator (RTDS) based relay test systems. The background of the developments in protection relays and their associated technologies, such as optical transducers and IEC 61850, are introduced. The new developments in RTDS systems are described. It is shown that the recent developments in transducers and communication technology will have great impacts to the developments of protection relays and their associated RTDS based relay test systems. The paper further describes the existing, new developments and future trend in the development of protection relays and their associated RTDS systems.
With the introduction of high-speed relaying systems, the need for extensive testing of these systems for different fault and abnormal conditions has become more important, to ensure the security and dependability of the electric power systems. Testing of relays can be summarized into three groups: steady state, dynamic and transient. While the first two types are performed during bench testing, they are not adequate for performance evaluation of subcycle modern relays. Transient testing is performed for verification of relay performance under transient conditions of power system to address such requirement. ABB has been using real-time simulations of power systems, for relay performance evaluation, for around seventy years in the US. This paper discusses the methodology employed for real-time simulations of power systems with different technology, with specific focus on the state-of-the-art real-time digital simulator from EDF. Specific case study related to the performance evaluation of a line relay system is discussed in this paper.
The classical approach used to implement digital real-time power system simulators (DRTPSS) consists in modeling the power system network and devices in software, and using numerical integration techniques and parallel processors to solve the resulting equations. This approach has many advantages, but it is subjected to the processor-memory hardware paradigm and the inter-processor communication overhead. The latter imposes a minimum time step that cannot be much decreased even when using higher performance processors. Typically, the minimum time step reported in the literature is around 20 mus. This paper presents a new approach to design and implement high-performance DRTPSS that consists in modeling the power system network and devices directly in VLSI hardware. The network topology and device models are described in a hardware description language (HDL) and mapped to a programmable device (FPGA) by using automatic synthesis tools. The simulation runs directly in hardware resulting in very short simulation time steps. Indeed, the initial results obtained and presented in this work show that time steps in the order of microseconds are possible
This paper presents the design of new real time digital simulator (RTDS) based novel relay test systems. The background of the developments in protection relays and their associated technologies, such as optical transducers and IEC 61850, are introduced. The new developments in RTDS systems are described. It is shown that the recent developments in transducers and communication technology will have great impacts to the developments of protection relays and their associated RTDS based relay test systems. The paper further describes the existing, new developments and future trend in the development of protection relays and their associated RTDS systems.
This thesis proposes methods for modeling electric power transmission lines for the purpose of analog power flow computation of power system networks. Theoretical and applicable circuit models for analog transmission lines are presented with a focus on power-flow studies which concentrates on the steady state or static behavior of electrical power transmission lines. With this approach the wave propagation and reflection is not as much of a concern as the steady state line voltages and current flows. Because of this lumped circuit equivalent line models are utilized. The primary goal is to develop a computational alternative for power system analysis that overcomes obstacles currently faced by traditional digital computation methods. Analog computation is proving to be a viable alternative and has notable advantages over digital computers. In order to contrive a practical analog emulator precise models for power system components are required. Specifically this thesis develops a realization of an electric power transmission line model for such a purpose. The transmission line model traditionally utilized in power-flow computation is a lumped parameter pi-model equivalent circuit. In digital computation the shunt elements and sometimes the series resistances are often times neglected in order to simplify the power flow equations and subsequently speed up the calculation times. Prior research in analog computation for power flow analysis also utilized these simplified line models. A fully reconfigurable pi-model is presented here for an analog computation approach. No components have been neglected resulting in a more accurate line model with fast computation times. The ability to remotely reconfigure each component on the line model makes this model universal. The design could easily be fabricated to an integrated circuit to represent a large scale network and configured to match a real world system. In addition, the model is easily expanded to form a distributed parameter line model by interconnecting multiple components in series. This allows for computational analysis of the power system states throughout the transmission line which is traditionally not done in digital power flow computation due to computational restraints.
This paper reports on the developments of the real time digital simulator (RTDS) based test systems for protection relays. The background of the developments in protection relays and their associated technologies, such as optical transducers and IEC 61850, are introduced. New developments in RTDS systems are described. It is shown that the current development in transducers and communication technology will have great impact on the developments of protection relays and their associated RTDS based relay test systems. The paper further describes the current, new developments and the future trend in the development of protection relays and their associated RTDS systems
A concept to improve the numerical performance of electromagnetic transients simulators at a minimum computational burden is proposed. It is based on the use of different numerical integration methods as a function of locally varying characteristics of the network model. It is shown that the concept is numerically very efficient and therefore compatible with the requirements of modern real time simulators for electromagnetic transients. The application and the benefits of the scheme are clarified by means of an HVDC simulation study.
A brief history of analog simulators is given leading up to the
development of the new types of digital simulator. Examples of the older
analog simulators is followed by examples of their digital counterparts.
Typical output waveforms from the new simulators are shown both in
playback and interactive mode. Specific examples are given of the
increase in testing efficiency using the new real time digital
simulators with a batch testing feature
Real-time power system simulator testing has proven to be an
invaluable means to evaluate relay performance under realistic
conditions. This paper exposes the configuration and the performance of
a real time digital transient network analyser (DTNA) in closed loop
testing of a distance protection system in a series compensated network.
A power system simulator for relay testing should be flexible in
configuration and parameter adjustment and it should provide for a rapid
execution of test cases. It must not only function in real time, but in
a closed-loop mode with relays tripping circuit breakers within the
simulator. This paper describes the ARENE DTNA
Fields of interest for the use of real time digital simulators for
electromagnetic transients include the testing of power system devices
such as controllers and protective relays in high voltage direct current
(HVDC) systems. The accuracy of real time HVDC simulations is strongly
influenced by the way the switching processes and the quantities which
constitute the inputs to the controllers are dealt with by the
simulation algorithms. In this paper a simulation algorithm for the real
time simulation of the extinction advance angle, which is processed by
the HVDC controller, is presented. A case study involving the well-known
CIGRE HVDC benchmark system is used to demonstrate the resulting quality
improvement which is achieved
Real-time power system simulator testing provides an invaluable
means to evaluate relay performance under realistic conditions.
Simulator testing has been, and will continue to be, essential for
achieving reliable transmission line relaying and it is expected to
contribute to improved designs in other areas of protection, as for
example in transformer protection relaying. Examples of testing of line
protection and transformer protection are described
In this paper, a multirated scheme based on filter banks is proposed for networks modeling in electromagnetic transient calculation. The basic idea is to convolve in the sub-bands using models of different complexity for the lowand high-frequency range in order to reduce the overall computational complexity. The proposed scheme is intended to be primarily used in real time calculation algorithms, either in full digital or in hybrid applications, where very efficient models are required to fulfill stringent time performance requirements. The results show that a substantial reduction of computational demand can be achieved without significant loss of accuracy for networks with parameters within the usual rank.
A few years ago, the study and simulation of fast power system
phenomena in real-time, was the private ground of analog simulators. But
the limitation in modeling, the complexity and the costly maintenance of
these simulators was a brake upon their development and made their
profitability uncertain. The testing of power system equipment such as
controls, relays or power electronic devices needed a new type of
simulator, much more versatile and cost-efficient than their
predecessors: the real-time digital transient network analysers (DTNA).
Until a few months ago, the design of DTNAs was based on dedicated
technologies. Today, the ever increasing calculation power has now
reached a level that allows real-time simulations of fast phenomena to
be carried on standard computers. The authors present in this paper a
new and fully digital TNA that relies on a standard computer
Working group F-8 “Digital Simulator Performance
Requirements for Relay Testing” of the Relay Input Sources
Subcommittee, Power System Relaying Committee, was formed in 1992 with
the following assignment: “Investigate performance characteristics
of digital simulators when generating electromagnetic transient program
(EMTP) and digital fault recorder (DFR) based relay test waveforms.
Write performance requirements specifications and prepare a paper
describing the importance of the simulator performance
characteristics.” This paper presents the work accomplished by the
working group in fulfilling its assignment
This paper discusses characteristics of a new digital simulator
for protection relay testing. The most demanding design requirement is
computation of fault transients under the condition of real-time change
of power system configuration due to relay operation. This problem is
solved using EMTP computational techniques enhanced with novel numerical
solutions for dynamic power system configuration change and nonlinear
element modeling. An advanced computer architecture is utilized to
achieve further optimization of the execution time for the transients
computation code. The main advantage of this design is the use of
conventional single processor computer architecture in combination with
advanced digital signal processors (DSPs). This makes this simulator an
off-the-shelf product with all the benefits of commercially available
computers priced at a relatively low cost
Electromagnetic transients in arbitrary single- or multiphase networks are solved by a nodal admittance matrix method. The formulation is based on the method of characteristics for distributed parameters and the trapezoidal rule of integration for lumped parameters. Optimally ordered triangular factorization with sparsity techniques is used in the solution. Examples and programming details illustrate the practicality of the method. Copyright © 1969 by The Institute of Electrical and Electronics Engineers, Inc.
A description is given of MORGAT, a digital simulator of
electrical transient phenomena occurring in transmission systems, used
for the study and testing of protection systems. Requirements regarding
accuracy of modeling and ease of use are reviewed, and the numerical
methods used in the program for simulating transients are briefly
examined. The man/machine interface, which allows the simulation program
to be used easily by those who are unfamiliar with computer techniques,
is presented. The hardware configuration of the digital model and the
interface with the tested devices are described
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 μs 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
A real-time digital model of a complete hydraulic synchronous
machine is presented. The model is based on parallel processing using
digital signal processors (DSP) for fast calculation. The modeling of
the machine using block diagrams to represent the generator, voltage
regulator, stabilizer, turbine, penstock and governor is described.
Details of the hardware and software used to implement the real-time
model of the machine are given. A first series of tests has been done,
and results are shown to evaluate the steady-state and transient
performance of the model