| Abstract: This paper describes an off-line simulation facility available at the University of Manitoba and the Manitoba HVDC Research Centre for assessing the transient performance of relays. The facility is based on a user friendly workstation environment whereby input and output information are presented in graphical form making it easy for the non computer expert to use sophisticated simulation tools to solve problems relevant to choosing and setting relays. |
| Abstract: This paper describes the design and performance of a digital transient network analyzer (DTNA) for testing relays. The DTNA uses a parallel processing architecture to run power system simulations in real time with a time step of 50-100 microseconds. Relays can be fed with the appropriate signals from the DTNA and the output from the relay trip circuit can be fed back into the simulation. Examples are given of tests on a commercial distance relay. |
| Abstract: This paper should provide an insight into this technique of minimization of uncharacteristic harmonics in HVDC convertors through firing angle modulation. |
| Abstract: FACTS (flexible ac transmission system) apparatuses employing many alternative configurations of power-electronic switching devices are being considered by others for increasing the power transfer capability of ac transmission lines. This paper introduces special modifications to the basic Dommel algorithm to expedite simulation of systems including arbitrary configurations of individual power-electronic switching devices. The described techniques have been implemented in a prototype transients simulation program. Two time-step sizes are used. Individual switching devices are represented according to simple characteristic curves. The modified algorithm includes iteration of a time-step when required to provide solutions on the curves. A technique is described for removing numerical oscillations of currents in capacitive loops and voltages at inductive nodes. Simulation results are presented for an example power-electronic apparatus. |
| Abstract: Two ultra modern power system simulation tools for the solution of electromagnetic transients are described. The EMTDC program is transients simulation software package which has been specifically designed to give the user increased freedom to model the most complex of devices and controls found in a modern power system. The Real Time Digital Simulator uses custom built parallel computing hardware to solve the same electromagnetic transients equations in real time. Both transients simulation tools share the same Graphical User Interface which encompasses the entire simulation process from design to analysis. The highly developed graphical front end combined with these advanced simulation tools produce a highly efficient environment for studying power system transients. |
| Abstract: Even a decade ago, the HVDC study tools were very limited and largely restricted to academic circles. It was then a difficult task to gather enough information for the preparation of a text book on the subject. In contrast, the past decade has witnessed many important contributions to the modelling of integrated ac-dc power systems, particularly in the area of dynamic simulation using the Electromagnetic Transient Program. Dramatic improvements in computer technology have practically eliminated the traditional criticisms (i.e. speed and cost) often made of the digital solutions. In fact, with the advent of dedicated parallel processing techniques, it is now even possible to carry out real time dynamic simulations. |
| Abstract: Three conditions must be met for a rigorous approach to the problem of verification of a computer algorithm, i.e. ;1. Comparing the proposed algorithm with one or more fundamentally different models. 2. Setting up identical test system conditions in each model. 3. Presenting all the relevant information needed to detect any deviations and the instances of their occurrence. With reference to hvdc transmission, the possibility of using real system information to assess the predictive ability of a computer simulation program, although often expected, is unrealistic owing to practical difficulties in meeting condition 2. A more realistic comparison, in terms of conditions 1 and 3 above is the use of two or more alternative and fundamentally different computer solutions. Two basically different approaches are currently used in hvdc transient simulation, i.e. the Electromagnetic transient program (EMTP) and the state variable technique. The EMTP method and a diakoptical solution have been combined into an efficient algorithm, the EMTDC, for the analysis of ac/hvdc power systems. State variable solutions, often reputed less efficient, are formulated in a more 'physical' form and use less approximations. they therefore provide suitable tools for rigorous comparison. If the response of the two methods to various disturbances can be made to agree, it will be reasonable to accept the validity of both. If they do not agree, at least one of them will not meet the criterion and without additional information it will be difficult to reach a positive conclusion as to the value of either. |
| Abstract: not available |
| Abstract: This paper describes a computationally efficient model for Metal Oxide Varistors (MOV) suitable for use in simulation studies of series compensated lines. It can also be used in simulators running EMTP type solutions in real time since it does not rely on an iterative technique for its implementation. Results are presented for simulation on a series compensated 500kV line and comparisons are made with a previously published study where field recordings are available for comparison. |
| Abstract: The paper describes a new Joint VAR Controller which was designed for use at Manitoba Hydro's Dorsey Converter Station. The controller was tested in closed loop mode using a fully digital real-time simulator. By performing a broad range of simulated system disturbances the controller's operation could be verified before its installation at site. |
